igneous layering, fractional crystallization and growth of granitic

Igneous Layering Fractional Crystallizationand Growth of Granitic Plutons the DolbelBatholith in SW Niger

E PUPIER1 P BARBEY1 M J TOPLIS2 AND F BUSSY3

1CRPG NANCY UNIVERSITEcurren CNRS BP 20 54501 VANDŒUVRE LE S NANCY CEDEX FRANCE2DTP OBSERVATOIRE MIDI-PYREcurren NEcurren ES 14 AVENUE EDOUARD BELIN 31400 TOULOUSE FRANCE3INSTITUTE OF MINERALOGY AND GEOCHEMISTRY ANTHROPOLE UNIVERSITY OF LAUSANNE CH-1015 LAUSANNE

SWITZERLAND

RECEIVED OCTOBER 2 2007 ACCEPTED MARCH 10 2008ADVANCE ACCESS PUBLICATION APRIL 19 2008

This study reassesses the development of compositional layering

during the growth of granitic plutons with emphasis on fractional

crystallization and its interaction with both injection and inflation-

related deformation The Dolbel batholith (SW Niger) consists

of 14 kilometre-sized plutons emplaced by pulsed magma inputs

Each pluton has a coarse-grained core and a peripheral layered

series Rocks consist of albite (An11) K-feldspar (Or96^99 Ab1^4)

quartz edenite (XMgfrac14 037^055) augite (XMgfrac14 065^072)

and accessories (apatite titanite and Fe^Ti-oxides) Whole-rock

compositions are metaluminous sodic (K2ONa2Ofrac14 049^062)

and iron-rich [FeOtot(FeOtotthornMgO)frac14 065^082] The layer-

ing is present as size-graded and modally graded sub-vertical rhyth-

mic units Each unit is composed of three layers which are towards

the interior edenite plagioclase (Cap) edenitethorn plagioclasethorn

augitethorn quartz (Cq) and edenitethorn plagioclasethorn augitethorn quartzthorn

K-feldspar (Ck) All phases except quartz show zoned microstructures

consisting of external intercumulus overgrowths a central section show-

ing oscillatory zoning and in the case of amphibole and titanite com-

plexly zoned cores Ba and Sr contents of feldspars decrease towards the

rims Plagioclase crystal size distributions are similar in all units sug-

gesting that each unit experienced a similar thermal history Edenite

characteristic of the basal Cap layer is the earliest phase to crystallize

Microtextures and phase diagrams suggest that edenite cores may have

been brought up with magma batches at the site of emplacement and

mechanically segregated along the crystallized wall whereas outer zones

of the same crystals formed in situThe subsequent Cq layers correspondto cotectic compositions in the QzÂbÔr phase diagram at

PH2Ofrac14 5 kbar Each rhythmic unit may therefore correspond to a

magma batch and their repetition to crystallization of recurrent magma

recharges Microtextures and chemical variations in major phases allow

four main crystallization stages to be distinguished (1) open-system

crystallization in a stirred magma during magma emplacement involv-

ing dissolution and overgrowth (core of edenite and titanite crystals)

(2) in situ fractional crystallization in boundary layers (Cap and Cqlayers) (3) equilibrium lsquoen massersquoeutectic crystallization (Ck layers)

(4) compaction and crystallization of the interstitial liquid in a highly

crystallized mush (eg feldspar intercumulus overgrowths) It is con-

cluded that the formation of the layered series in the Dolbel plutons

corresponds principally to in situ differentiation of successive magma

batches The variable thickness of the Ck layers and the microtextures

show that crystallization of a rhythmic unit stops and it is compacted

when a new magma batch is injected into the chamber Therefore

assembly of pulsed magma injections and fractional crystallization are

independent but complementary processes during pluton construction

KEY WORDS layered igneous rocks granite pluton magma chamber

fractional crystallization

I NTRODUCTIONFormation of plutons is currently considered to be theresult of incremental growth by pulsed injections of silicicor mafic magmas over various periods of time (egAranguren et al 1997 McNulty et al 2000 Petford et al2000 Coleman et al 2004 among a wealth of publica-tions) Nevertheless simple assembly of magma pulsesis not sufficient for understanding the petrological and

Corresponding authorTelephone333 8359 4234 Fax333 83511798E-mail barbeycrpgcnrs-nancyfr

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structural characteristics of granitic plutons (Spera ampBohrson 2001 Pons et al 2006) and consideration of addi-tional processes is required Although many processes havebeen proposed to occur in magma chambers during theformation of granitic plutons (Barrie re 1981 Parsons ampBecker 1987 Tobisch et al 1997 Hodson 1998 Wiebe ampCollins 1998 Wiebe et al 2002 Pons et al 2006) theirexact role and relative importance remain open to debateas illustrated for example by contrasting opinions con-cerning the origin of the Tuolumne Batholith in centralSierra Nevada (Glazner et al 2004 Zak amp Paterson2005) The aim of the present study is to reassess therole of processes that occur in magma chambers duringthe formation of granitic plutons with emphasis onthe role of fractional crystallization in boundary layers(ie in temperature and compositional gradients) and itsinterplay with new magma injection and inflation-relateddeformation during pluton growth and solidificationEven though the physical properties of basaltic and

granitic magmas are different the study of mafic igneouscomplexes provides insight into the magmatic processesoccurring during the construction of magma chambers inthe crust For example compositionally zoned minerals incumulate rocks are commonly interpreted in terms of thedegree of local melt differentiation and such chemical gra-dients can be used to constrain liquid evolution and resi-dence times (eg Maale 1976 Tegner 1997 Markl ampWhite 1999 Zellmer et al 1999 Jang amp Naslund 2001Boyce amp Hervig 2008 Toplis et al 2008) Similarlyunzoned crystals typical of adcumulate textures are inter-preted to be the result of small-scale convection in liquidsor diffusion leading to the progressive removal of intersti-tial porosity with little or no mineralogical and composi-tional variation relative to the cumulus assemblage (egMorse 1980 Hunter 1987 Tait amp Jaupart 1996) At longerlength scales modally graded layered sequences andlsquoturbidite-likersquo structures have been related to fractionalcrystallization in boundary layers and to crystal sortingand accumulation through density currents and large-scale convection (eg Wager amp Brown 1968 Morse 1980Parsons 1987 Cawthorn 1996 Irvine et al 1998)Returning to the case of more silicic and alkaline mag-

matic rocks noteworthy examples of igneous layering arewell known in syenite and granite plutons with rhythmicunits mineral grading cross-stratification and troughlayering (Wager amp Brown 1968 Barrie re 1981 Parsons1987 Parsons amp Becker 1987 Cawthorn 1996 Tobischet al 1997 Hodson 1998) These structures suggest thathydrodynamic sorting and thermal convection are alsolikely to occur in granitic plutons at least at the scaleof a single magmatic unit (Wiebe amp Collins 1998Weinberg et al 2001 Wiebe et al 2002 Pons et al 2006)Furthermore recent experimental and numerical studieshave shown that the viscosities of silicic magmas cluster

around 1045 Pa s and do not change significantly as longas the crystal fraction remains below 30^50 (Scailletet al 1996 1997 1998 Clemens amp Petford 1999) These vis-cosity values are lower than formerly considered thus itwould appear that viscosity is not an obstacle to convec-tion in silicic magma chambers (even though length andtime scales are likely to be different from those encoun-tered in mafic chambers) nor should it impede smallscale crystal^melt segregation Therefore the study ofigneous layering in granitic bodies may provide us withinformation on the role of magma chamber processesccedilespecially fractional crystallization in boundary layersccedilduring the construction of granitic plutonsThe assessment of the role of crystallization in a thermal

boundary layer requires careful choice of rock samplesFor example (1) layering formed by crystal settling andhydrodynamic sorting should be avoided as much as possi-ble and this restricts sampling to near-vertical layeringclose to the walls of plutons (2) deformation gradientsrelated to pluton inflation need to be moderate for theigneous textures to be preserved (3) bulk compositionsshould be close to experimentally determined phase dia-grams to have an appropriate reference frame (4) mineralphases should display chemical zoning allowing the extentof melt differentiation to be assessed In the light of theseconstraints the Dolbel batholith in SW Niger has beenselected for this study as it fulfils all of the above criteriaAfter a presentation of the plutons and their structural fea-tures we describe the microtextures and compositions ofthe main mineral phases and then discuss the developmentof the compositional layering during the course of plutongrowth with particular emphasis on fractional crystalliza-tion in boundary layers

GEOLOGICAL SETT INGThe Dolbel batholith (Liptako province SW NigerMachens 1967 Pons et al 1995) is located in the northeast-ern part of the Leo Rise (Fig 1a) an extensive 21Gagranite^greenstone terrane considered to be a major zoneof crustal growth (Milecurren si et al1989 Abouchami et al1990Boher et al 1992) The batholith consists of 14 kilometre-sized plutons forming a narrow NW^SE-trending beltperpendicular to the regional strike of the surroundinggreenstones (Fig 1b) The shape of the plutons deflectionof the country-rock schistosity and crosscutting relation-ships show that plutons were emplaced syntectonicallyin a northward-trending succession (g1 to g14) The smallsize of the plutons and their distribution along a NW^SElinear array parallel to the direction of regional shorteningwere considered by Pons et al (1995) to result from pulsedmagma ascent and ponding controlled by regional defor-mation that created a series of large tension gashes parallelto the 1 direction

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STRUCTURE AND ROCK TYPESOF THE DOLBEL PLUTONSAll plutons consist of low-Ca plagioclase (An11)K-feldspar quartz amphibole clinopyroxene and acces-sory minerals (principally titanite apatite and magnetite)The proportions of ferromagnesian minerals average 5 vol but may be locally significantly higher (20)As shown by Pons et al (1995) the plutons can be sub-divided into two main parts (1) a coarse-grained coreconsisting of granite showing only a weak fabric (2) aperipheral layered series with a zone of high strain at themargin The core of the plutons consists of porphyriticgranite that contains sparse microgranular mafic enclaves(Fig 2a) which may occur in swarms and correspondto proto-dykes Locally K-feldspar phenocrysts form

irregular accumulations (Fig 2b) These phenocrysts aregenerally of larger grain size than in the layered seriesbut display similar zoning patterns (Fig 2c)

Structure of the plutonsThe structure of the Dolbel plutons has been described byPons et al (1995) and only the principal characteristics aresummarized here In all plutons the fabric is sub-verticalsub-parallel to the igneous layering and parallel to the con-tact with the surrounding schists (cylindrical geometry)The fabric corresponds to a schistosity in the peripheryof the plutons It is particularly well expressed in the larg-est g2 pluton close to the contact with the host-rockswhere the zone of high strain may exceed 10m in thicknessHere the granite looks like an orthogneiss with intenseplastic deformation of minerals (elongated quartz grains

country-rock schistosity

γ granite plutons

greenstones

dune

radial dykes

conjugate shear-zones

granite planar structures

γ14

14deg30prime

1deg20prime

1deg20prime

Dolbel

γ13

γ12

γ10 γ9 γ7

γ5

γ2

γ1

γ3

γ4

γ6γ8

γ11

0 1 2 kmN

2deg

13deg

14deg

Sirba

Torodi

DargolDoundielTera

Bellekoire

Dolbel Niger

Darbani

1deg

BU

RK

INA

FASO

500 km

granite plutonsgreenstone belts

NIAMEY

DOLBELBATHOLITH

sedimentary cover

Gotheye

2deg

LeoRise

(a)

(b)

track

lineation

Ayorou

Fig 1 Geological maps of (a) the Liptako area (SW Niger) and (b) the Dolbel batholith Redrawn from Pons et al (1995)

PUPIER et al GROWTHOF GRANITIC PLUTONS


asymmetric recrystallized pressure shadows aroundrotated K-feldspar phenocrysts see Pons et al 1995 fig 7)In the rest of the pluton the fabric highlighted by thepreferential orientation of amphibole and feldspars freeof plastic deformation can be defined as a lsquopre-full crystal-lization fabricrsquo (Hutton 1988)Shear zones are conspicuous in the periphery of the

g2 pluton Close to the contact they deflect the schistositysideways and are associated with intense plastic

deformation suggesting that they were produced duringthe late stages of pluton consolidation by ductile deforma-tion of the outer shell of the pluton Towards the plutoninterior shear zones tens of centimetres long are weaklydefined by the orientation of plagioclase crystals (sub-magmatic deformation) They cut across the foliationwithout deflection or plastic deformation (see Pons et al1995 fig 8) The geometry of the shear zones (sub-verticalconcentric in conjugate or parallel sets horizontal sense

(a)

(c)

(d)

(e)

(b)

Kfs

Kfs

Kfs

Kfs

Fig 2 Field photographs of the Dolbel g2 pluton (a) Homogeneous porphyritic granite in the core with sparse mafic microgranular enclaves(arrowed) (b) Local accumulation of K-feldspar phenocrysts in the core of the pluton (c) Thin oscillatory zoning in K-feldspar outlined byweathering (d) and (e) Sub-vertical inward-dipping igneous layering in the periphery of the intrusion showing dark amphibole-rich layers atthe base and porphyritic granite at the top (pluton core located to the left) Arrows indicate amphibole-riche basal layers Scale bar represents10 cm except in (c) where it represents 1cm



of displacement) is systematic where they occur The con-jugate shears make an angle of 50^608 and the acute bisec-tor of the angle corresponds to the foliation or to theschistosity The geometry of the conjugate shear zones thedirections of displacement and the general monoclinicsymmetry of the fabric show the rotational nature of thedeformation with extension along the direction of strikeof the schistosity and flattening perpendicular to the con-tact of the pluton This along with the elliptical shape ofthe g2 pluton and the deflection of the country rock schis-tosity (Fig 1b) indicates interference between regionaldeformation and inflation of the pluton by the injection ofmagma in its centre The parallel nature of the contact ofthe pluton the layering the submagmatic foliation and thesubsolidus schistosity together with the systematic geome-try of the shear zones preclude any significant change inthe dip of layering during the course of pluton growthThe presence of vertical radial dykes of aplite and

quartz veins in the outermost parts of the plutons andin the nearby country rocks corroborates the existence oftensile stress concentric to the plutons with flattening ofthe consolidated outermost shell (subsolidus deformation)Pons et al (1995) considered that emplacement of theDolbel plutons resulted from the interference between theregional strain field and a local strain field induced byinflation of the pluton caused by repeated inputs of freshmagma which led to incremental finite strain in the outerpart of the plutons

The layered seriesData presented here and in the subsequent sections wereobtained from the g2 pluton unless otherwise statedLayering corresponds to rhythmic variations in sizenature and proportions of minerals [the nomenclatureused here is that of Irvine (1982)] It is sub-vertical dipssteeply inwards (Fig 2d and e) and is parallel to the con-tact of the pluton Layering consists of rhythmic units thatdiffer in width although any single unit maintains a ratherconstant width along its strike at outcrop-scale As a resultof very discontinuous outcrop conditions the thickness ofthe whole layered series is difficult to estimate but exceedsseveral tens of metres For the same reason the sampledlayering has been followed along its strike only over severaltens of metres The layering is described from one polishedslab (Fig 3) which is composed of four rhythmic cumulateunits (C1 to C4) Mineralogical and geometrical character-istics of the four units are presented inTable 1 Of these fourunits two are complete in terms of their mineralogical suc-cession (C3 and C4) another is complete but was truncatedwhen the sample was collected (C1) and the fourth isincomplete (C2) as it is missing its uppermost part Takingthe C3 unit as a reference a typical unit is consideredto consist of three layers (Cap Cq Ck) each characterizedby the appearance of a new cumulus mineral amphiboleplagioclase quartz and K-feldspar

The lower dark Cap layers show a sharp basal contact(Fig 2d and e) At their base they consist almost exclusivelyof amphibole (thorn apatite titanite Fe-oxide) whereastowards the top both amphibole and plagioclase occur ascumulus phases Plagioclase grains are low in abundanceand of smaller size than in the subsequent layers TheCq layers consist of cumulus plagioclase and quartz asthe dominant minerals In the Ck layers plagioclasequartz and K-feldspar are cumulus phases Size grading isparticularly obvious for cumulus plagioclase and will bedescribed in more detail below A few clinopyroxenecrystals also occur as a cumulus phase in the Cq and Ck

layersWith the exception of quartz and clinopyroxene allcumulus mineral phases are compositionally zoned withremarkable oscillatory zoning Intercumulus material con-sists mainly of quartz and K-feldspar accompanied inlesser proportion by plagioclase and exceptionally byamphibole Intercumulus minerals are not zoned with theexception of a few intercumulus overgrowths The propor-tion of intercumulus minerals (Table 1) is around 23^30in the Cq and Ck layers but negligible in the Cap layersSmall mafic microgranular enclaves (millimetre to centi-metre sized Fig 3) are scattered within the layered seriesA few K-feldspar phenocrysts are locally present at thebase of the rhythmic units

Whole-rock compositionsWhole-rock analyses (see Appendix for analytical meth-ods) of porphyritic granite from several pluton cores(Table 2) show major element compositions similar tothose of sub-alkaline metaluminous granites with [Al2O3(CaOthornNa2OthornK2O)]molar ratios ranging from 079 to095 and [Al2O3(Na2OthornK2O)]molar ratios rangingfrom103 to 114They are distinguished by their predomi-nantly sodic compositions (K2ONa2Ofrac14 049^062) andrather high FeOtot(FeOtotthornMgO) ratios (065^082)Most trace element concentrations are low includingthe rare earth elements (

PREEfrac14136^422 ppm) Only

Ba and Sr show high concentrations (averages 2037 463and 1264340 ppm respectively) Bulk major elementcompositions of the C2q C3q C1k and C3k layers are pres-ented inTable 2 The Ck layers are not significantly differ-ent from the porphyritic granite samples whereas the Cq

layers differ by higher FeOtot MgO and REE contentsbut lower Al2O3 K2O and Ba contents (65081ppm)Bulk mineralogical proportions (wt ) of the Cap Cq

and Ck layers are given inTable 1REE patterns normalized to chondrite (Fig 4) are simi-

lar in the samples from the core and the layered seriesThe REE are fractionated [(LaYb)Nfrac14 4 4^70] withconcave-upward heavy REE [(GdYb)Nfrac1415^21] andpositive Eu anomalies (EuEu frac1411^19) The Cq samplesshow higher REE concentrations than the Ck layers andporphyritic granites these higher values being probablyrelated to higher proportions of titanite It should be



noted that the bulk REE contents in the Dolbel samplesare significantly lower than those generally observedin A-type granites which typically show chondrite-normalized Ce and Yb concentrations at least 100 and 30times chondrite respectively (eg Collins et al 1982)

MICROTEXTURES ANDCOMPOSIT IONS OF MINERALSChemical compositions of minerals were determined byelectron microprobe for major elements (c 800 analyses)and by laser-ablation inductively coupled plasma mass

spectrometry (ICP-MS) for trace elements (see Appendixfor analytical procedures) Selected mineral compositionsare presented in Table 3 (the complete dataset is pro-vided as Supplementary Data available from httpwwwpetrologyoxfordjournalsorg)

Ferromagnesian mineralsClinopyroxene occurs as sparse euhedral crystals (0206mm to 0420mm) in the Cq and Ck layers Theyare commonly surrounded by a thin rind of secondaryactinolite but in general they remain as small remnantspartially replaced by an aggregate of secondary magnetiteepidote K-feldspar and quartz In the classification of

C1

Ck CkCqCqCap Cap CkCqCap

C2 C3 C4

Pluton centre

2 cm

microgranular mafic enclave

base of theC3 layer

top of theC3 layer

Fig 3 Polished slab of layered granite from the g2 plutonThe sample comprises four rhythmic units (C1 to C4) complete units consist of threesuccessive layers Cap (amphthornpl) Cq (amphthornplthornqtz) and Ck (amphthornplthornqtzthornKfs)



Morimoto et al (1988) the clinopyroxene corresponds toaugite (0655XMg5077) close to the field of diopside(0415XWo5046) and with a limited acmite component(0085XAc5012)Amphibole is a ubiquitous phase although it is more

abundant in the basal layer of each rhythmic unit (Cap)It occurs as clusters of euhedral grains ranging in sizefrom 005012mm to 0708mm and as inclusions infeldspars (locally in plagioclase laths more generally ininterstitial K-feldspar) It consists dominantly of darkgreen ferro-edenite and is commonly surrounded by alight green rim of secondary actinolite (Fig 5a) In back-scattered electron images ferro-edenite shows systematicoscillatory zoning which is absent in actinolite Zoningpatterns allow three parts to be distinguished in the ferro-edenite portion (1) a core showing disjointed zoning withcrosscutting relationships and synneusis suggesting trans-port agglomeration dissolution and overgrowth of thecrystals (Fig 5b) (2) an intermediate part in which thinoscillatory zoning is parallel to the growth faces of crystals(Fig 5c and e) (3) intercumulus overgrowths showinga progressive compositional variation towards the rim(Fig 5d) These textures are very similar to those reportedin phenocrysts from certain dacitic lavas such as those fromUnzen volcano (eg Sato et al 2005)The composition of the primary zoned amphibole

(Fig 6a) encompasses the fields of ferropargasite ferro-edenite and edenite (0375XMg5055) Secondary actino-lite shows XMg values ranging from 049 to 068Two maintypes of major element variations are observed in

amphibole (excluding actinolite) The first is related toeither oscillatory zoning or core^rim variations (Fig 7a)A rimward decrease in XMg also occurs locally in intercu-mulus overgrowths (Fig 6f) The second type of variationcorresponds to an abrupt change at the top of the C3ap

layer characterized by an increase in Fe2thorn Altot and Kthorn

and a decrease in Mg2thorn and Ti4thorn contents when passingfrom the C1k^C3ap layers to the C3q^C4k layers (Fig 6b^d)Otherwise there is no systematic evolution of major ele-ment composition of amphibole from one layer or fromone rhythmic unit to anotherTrace element concentrations were determined by laser-

ablation ICP-MS (see Appendix for the analytical meth-ods) on a zoned crystal from the C2ap layer (analyticalspots in Fig 5e) Concentrations of Ba Sr Ti and V showthe highest values in the core with a decrease in the inter-mediate oscillatory-zoned part and then a slight increasetowards the rim (Fig 7) Concentrations of Ce are low inthe core increase in the intermediate part and thendecrease in the rim These variations are similar to thoserecorded in titanite (see below)

PlagioclaseMicrotexture and composition

Plagioclase crystals show two distinct parts irrespectiveof their position in the rhythmic units (Fig 8a and b)(1) large cores with faint oscillatory zoning (2) over-growths of variable thickness (01^04mm) part of whichis clearly intercumulus Crystals are commonly tiled(Fig 8b) Locally plagioclase may be indented by adjacent

Table 1 Mineralogical composition and thickness of the Ca to Ck layers of the four rhythmic units (sample D90-18

g2 pluton)

Layer Cumulus phasesIntercumulus

Name Thickness (cm) Main phases (wt ) Subordinate phases (1) (vol )

Unit 4 (76 cm thick)

C4k 43 (incomplete) plagioclase (64) K-feldspar (8) quartz (16) amphibole (11) Cpx Ox Tit Ap 27

C4q 29 plagioclase (64) K-feldspar (3) quartz (18) amphibole (15) Cpx Ox Tit Ap 28

C4ap 04 amphibole (480) plagioclase (520) Ox Tit Ap mdash

Unit 3 (6 7 cm thick)

C3k 38 plagioclase (61) K-feldspar (12) quartz (13) amphibole (12) Cpx Ox Tit Ap 25

C3q 26 plagioclase (54) quartz (22) amphibole (22) Cpx Ox Tit Ap 27

C3ap 03 plagioclase (520) amphibole (480) Ox Tit Ap mdash






Intercumulus phases consist dominantly of quartz and K-feldspar



crystals with evidence of resorption by pressure-solution ofthe overgrowth and to a lesser extent of the core (Fig 8a)Plagioclase composition is albitic with a low anorthitecomponent (An0^11 Fig 9a) The anorthite content ofthe cores though typically An7 is variable because ofoscillatory zoning and secondary alteration In somecases overgrowths show an increase in An content which

then gradually decreases towards the contact with adjacentphases (Fig 9b) Ba and Sr are the sole trace elements pre-sent in significant amounts in plagioclase (Fig 10) Despitesignificant heterogeneity in core concentrations Ba showsa systematic decrease in abundance towards crystal rimsSr contents are even more heterogeneous but display thesame compositional trends as BaThese compositional pat-terns are common to all plagioclases of the four units

Crystal size distribution

In addition to geochemical observations the crystal sizedistribution (CSD) may also provide insight into the high-temperature history of magmatic rocks (eg Marsh 1998)The length width and area of plagioclase crystals weredetermined using NIH Image software (see Pupier et al2008) Lengths and widths are defined as the majorand minor axes of the best-fitting ellipse of the two-dimensional crystal sections In three dimensions plagio-clase shape can be considered as orthogonal and definedby short (X) intermediate (Y) and long (Z) axes For thecase of orthogonal crystals repeated measurement of thewidth of randomly chosen sections provides an estimate ofthe short axis X of the solid (Higgins 1994 2000) In thecase of plagioclase this represents the width perpendicularto 010 Following Higgins (1994) [and as confirmed byDucheldquo ne et al (2008)] for each size class the values of crys-tal number density measured in two dimensions [Na(L)]were converted to values corresponding to a numberdensity per unit volume Nv(L) using the equationNv(L)frac14Na(L)(D 064) where N(L) is the totalnumber of crystals whose size is smaller than L and D isthe mean size [frac14(XthornYthornZ)3] For the calculation ofD X is considered as the midpoint of the interval LwhereasYand Z may be calculated from independent con-straints on crystal shape (ie from known values of XYandYZ) Here an X YZ ratio of 1222475 has been used

Table 2 Major (wt ) and trace (ppm) element

composition of homogeneous porphyritic granite samples

from the core of four plutons of the Dolbel batholith and of

the C2q C3q C3k and C1k layers from the g2 pluton

Pluton core Layered series

Sample D28 D17 D48 D41 C2q C3q C3k C1k

SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006

FeOtot total iron as Fe2thorn LOI loss on ignition mdash belowdetection limit

pluton core

layered series (Ck)layered series (Cq)

La Ce Nd Sm GdEu LuDy Er Yb10

100

1000

Fig 4 Chondrite-normalized rare earth element patterns of por-phyritic granites from pluton cores and of Cq and Ck layers from thelayered series Normalization values from Evensen et al (1978)



based upon a 3D reconstruction of sequentially polishedsections of an experimental sample (Duchene et al 2008)We note in passing that the chosen values of XYand YZhave almost no effect on the relative CSDs determined indifferent layers although the absolute position of the CSDsmay be affected to some extentPlagioclase crystals are tabular with average size

increasing towards the top of each unit (0206mm

to 1743mm) Plagioclase CSD has been determined ineach rhythmic unit Measurements were made on euhedralplagioclase grains from all layers (avoiding intercumulusovergrowths) from thin sections cut perpendicular to thelayering and planar fabric The presence of a fabric is notan obstacle for measurements as it simply leads to X Yand Z values closer to the true values The number of mea-sured grains ranges from 62 for the C2 unit to 292 forthe C4 one The data are available as SupplementaryData at httpwwwpetrologyoxfordjournalsorg CSDcurves (Fig 11) are similar in all the units and display alog^linear shape for large grain sizes Slopes and interceptsof the regression lines in the different units are similar toeach other for both short and long axes of the crystalsRatios of the area occupied by plagioclase relative to thewhole surface area of each unit (measured perpendicularto the layering) are not significantly different (57 44 45and 49 for C1 to C4 units respectively) implying thatmodal proportions are the same in each layer All thesedata are consistent with the suggestion that crystallizationconditions were similar in all four units that is eachrhythmic unit records the same broad thermal historyThe small size of plagioclase grains at the base of eachrhythmic unit is of note as it suggests significant T

values between the top and the base of two consecutiveunits

K-feldsparK-feldspar is the characteristic phase at the top of therhythmic units (Ck layers) but it is also present as rareisolated grains within other layers (eg C3q layer in Fig 3)The thickness of these Ck layers shows large variationsome are only a few centimetres thick whereas others arealmost 1m thick Ck may even be absent as in the incom-plete C2 unit K-feldspar occurs as pink phenocrysts(34mm) which show a slight increase in sizetowards the top of each Ck layer (57mm) and assmaller anhedral intercumulus grains (006 008mm to0203mm) Phenocrysts contain inclusions of euhedralto subhedral laths of plagioclase euhedral edenite crystalsand in a few cases subhedral rounded quartz grainsThe K-feldspar phenocrysts in the C1k C3k and C4k layersare homogeneously distributed This may be appreciatedfrom histograms of distance between K-feldspar pheno-cryst nearest neighbours (Fig 12b) and is in contrast towhat is observed in porphyritic granites from the plutoncore in which K-feldspar phenocrysts are unevenly distrib-uted with local accumulations (Fig 2b) K-feldspars havelow albite component (Or96^99 Ab1^4 Fig 12a) with theexception of a few perthites Apart from the thin oscilla-tory zoning there is an overall increase in Or and corre-lated decrease in Ab components towards grain edges(Fig 12c) Back-scattered electron images (Fig 8c and d)together with concentrations of Ba and Sr (Fig 13)show that phenocrysts from all Ck layers consist of three

Table 3 Selected mineral compositions from the C3

rhythmic unit

Layer C3ap C3ap C3q C3q C3k C3q C3k C3ap

Mineral Ed Act Cpx Plag Kfs Mgn Tit Ep

SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125

Mg(Mgthorn Fe2thorn) 038 066 067

Ab 923 25

An 74 00

Or 02 975

Ed edenite Act actinolite Cpx clinopyroxene Plagplagioclase Kfs K-feldspar Mgn magnetite Tit titaniteEp epidote



distinct parts A perthitic core shows clear oscillatoryzoning in Ba but at higher concentrations than the periph-ery and overgrowths Apart from spikes related to theoscillatory zoning and secondary alteration the variationof Ba concentrations show an overall concave-downwardshape with decreasing values towards the rim A euhedralperiphery also shows oscillatory zoning but is free of exso-lution It shows a significant decrease in Ba contentThe external part corresponds to irregular overgrowthsdominantly as intercumulus material enclosing all theother minerals The Ba concentrations in these over-growths are significantly lower than in the core and per-iphery Sr is much more variable than Ba but shows the

same trend with a decrease in concentration towards theperiphery of the crystals

Microtexture and composition of othermineralsQuartz occurs as subhedral to euhedral millimetre-sizedcumulus crystals in the Cq and Ck layers and as an ubiqui-tous intercumulus phase Its size increases towards thetop of each rhythmic unit reaching 3mm No zoning wasobserved using cathodoluminescence microscopyApatite titanite and Fe^Ti-oxides are cumulus minerals

associated with amphibole especially in the basal Cap

layers Apatite occurs as small euhedral zoned grains

(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit

Fig 5 Back-scattered electron images of amphiboles from the layered series (C2a layer) (a) Oscillatory zoned ferro-edenite (light) partlyreplaced by actinolite (dark) at its periphery (b) Ferro-edenites showing complex zoning in cores and regular euhedral zoning in the peripherythe presence of a synneusis microtexture should be noted (upper right arrowed) (c) Euhedral lath-shaped edenite crystal showing patchy coreregular euhedral zoning and local retrogression into actinolite (d) Intercumulus external part of an amphibole showing gradual changein composition (numbered filled squares refer to analyses of Fig 6f) (e) Location of analytical spots in a zoned amphibole (numbers referto Fig 7) Scale bar represents 50 mm



1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1

position in the sequence

Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl

C1 C2 C3 C4Rhythmic units

Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim

Fig 6 Composition of the amphiboles from the layered series (a) and (b) Amphibole compositions from the four rhythmic units plotted onthe classification diagrams of Leake et al (1997) showing that primary amphiboles consist mainly of ferro-edenite whereas their overgrowthscorrespond to secondary actinolite (c) Variations of Fe2thorn content (atoms per formula unit) in ferro-edenite as a function of position in therhythmic units (note the change just above the C3ap layer) (d) and (e) Mg2thorn vs Fe2thorn and Altot vs Si plots also showing the abrupt change atthe top of the C3ap layer (f) Variation in Altot Si Ca (apfu) and XMg in the intercumulus overgrowth of Fig 5d showing a gradual decreasein XMg and Si towards the edge of the crystal and correlative increase in Altot and Ca



(02mm wide basal sections) Titanite occurs as euhedralgrains (002005 to 01 05mm) containing quartzand ilmenite inclusions Back-scattered electron imagesshow complex zoning patterns with resorption in the coreand euhedral growth zones at the grain edges (Fig 14a)Major and trace element compositions determined bylaser-ablation ICP-MS across a zoned grain (Fig 14e)show gradual depletion in Sr towards the rim whereas VTh Y and REE have a more complex profile consistentwith the variations of Al2O3 FeO and CaO For instancethe concentrations in Al2O3 V Th and

PREE are rela-

tively constant in the core decrease across the intermediatezone and then increase significantly in the wide peripheryThese variations are reminiscent of that observed inamphibole (Fig 7) Magnetite occurs as ovoid grains

(02^10mm in size) in all layers (Fig 14b and d) andsome grains have a thin rind that is enriched in Ti(Fig 14c) It may be locally retrogressed to hematiteIlmenite has been observed only as small inclusions(550 mm) within titaniteIn addition to actinolite that replaces the periphery

of edenite crystals the main secondary phases are rare car-bonate grains associated with amphibole and pistachiteoccurring as small grains or as larger area of symplectitewith quartz in Cap layers

DISCUSS IONAmong the various mechanisms proposed to account forthe formation of igneous layering in mafic bodies (see egNaslund amp McBirney 1996) two main processes are com-monly invoked

(1) hydrodynamic sorting related to density currents inmagmatic suspensions either by crystal segregationrelated to a velocity gradient along a static wall orcrystal settling related to material transfer towardsthe base of growing plutonic bodies (eg Barrie re1981 Parsons amp Becker 1987 Tobisch et al 1997Weinberg et al 2001 Wiebe et al 2002 2007 Ponset al 2006)

(2) fractional crystallization in thermal boundary layersat the margin of magma chambers (eg Irvine 1982Irvine et al 1998)

Considering the near-vertical geometry of the layeringin the g2 Dolbel pluton and the absence of mineral grad-ing cross-stratification trough layering and schlierencrystal settling related to density currents can be ruledout In the following sections we first discuss our data inthe light of phase diagram constraints and then explorehow the interplay of segregation in velocity gradients andfractional crystallization can explain the textural mineral-ogical and chemical characteristics of the layered series

Sequence and conditions of crystallizationThe mineralogical chemical and textural data describedabove provide numerous constraints on the physical andchemical processes that have led to the present-day layer-ing For example the repetition of identical cumulatesequences from one rhythmic unit to another is interpretedto indicate that the parent melt for each unit was very simi-lar Given that whole-rock compositions are dominatedby the four oxides SiO2 Al2O3 Na2O and K2O (theirsum reaching 93 on average) and that plagioclase com-position is close to pure albite (An0^11) the Dolbel datamay be satisfactorily represented and modelled in theQzÂbÔr haplogranite phase diagram In light of thisfact it is immediately apparent that excluding the basalamphibole-rich part of the Cap layers the principalchanges in phase equilibria within a given unit are

400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim

euhedrally zonedintermediate part

(a)

4

1

10

12

13

16

Fig 7 Element variations in a ferro-edenite crystal (Fig 5e)(a) XMg (b) Ba and Sr (c) Ti and V and (d) Zr and Ce Numbersin (a) refer to analytical spots



consistent with an evolution involving liquidus (plagioclasein Cap) cotectic (plagioclasethornquartz in Cq) and eutectic(plagioclasethornquartzthornK-feldspar in Ck) phase assem-blages in the QzÂbÔr system (Fig 15a) for parentmelts located in the primary field of Albite This is consis-tent with textural evidence showing that liquid saturationin K-feldspar occurred after amphibole plagioclase andquartz Furthermore evidence for eutectic assemblagessuggests pressure conditions of crystallization 5 kbar(Johannes amp Holtz 1996) in agreement with the meta-morphic phase assemblages (kyanitethorn staurolite) reportedby Pons et al (1995) in the surrounding metasedimentaryseries and with Al-in-hornblende barometry results(4114 kbar on average) determined from the Altot con-tent of edenite using the calibration of Schmidt (1992)Taking the C3 rhythmic unit as a reference we may

assess to what extent the different cumulate layers repre-sent successive instantaneous solid compositions resultingfrom fractional crystallization during cooling If we dis-card amphibole which will be discussed below cumulusplagioclase from the C3ap layer automatically has the com-position of the liquidus phase assemblage However it is of

note that the amount of plagioclase present in the Cap

layer is much lower than that expected based upon thephase diagram assuming a parent liquid containing20 normative quartz (see below) This low proportionof liquidus plagioclase may be the result of delayed orslow crystallization because of undercooling as observedin experimental studies of plagioclase nucleation in basal-tic compositions (Gibb 1974 Walker et al 1976 Dowty1980 Tsuchiyama 1983) The situation for silicic melts isless clear although a theoretical study by Kirkpatrick(1983) suggested that crystallization may indeed be slowa conclusion consistent with the sluggish crystallizationkinetics of plagioclase observed experimentally by Couch(2003) in a haplogranite systemMoving up-sequence the bulk major element composi-

tion of the C3q layer plots close to the Ab^Qz cotectic inthe QzÂbÔr diagram (Fig 15a) However given thegeometry of the phase diagram (Fig 15) this observationdoes not necessarily imply that the layer C3q has the com-position of the original local liquid This is because segre-gation and removal of eutectic melt interstitial to cotecticproportions of cumulus plagioclase and quartz results in

(a) (c)

(b) (d)

Fig 8 Microtextures of feldspar from the layered series in back-scattered electron images (a) Zoned plagioclase showing indented structurelacking the dark rim (arrowed) white line shows the location of the compositional profile shown in Fig 9b (C1k layer) (b) Tiled plagioclasecrystals from the C1k layer showing the rims (cross-polarized light image) (c) Ovoid K-feldspar phenocryst showing an oscillatory zoned corea periphery and intercumulus overgrowths (C4q layer) (d) K-feldspar phenocryst showing three parts core periphery and intercumulusovergrowths the white line shows the position of the compositional profiles shown in Figs 12 and 13 (C3k layer) Scale bar represents 05mm



bulk compositions that appear to occur along the liquidcotectic In other words an unconstrained (but necessarilyincomplete) fraction of interstitial eutectic liquid may havebeen removed from this layer during crystallizationMoving to the uppermost layer of the sequence we find

that the composition of the C3k layer is far from the eutec-tic and does not represent the crystallization product of theresidual melt resulting from differentiation of the C3q layerIt corresponds much more probably to the product of equi-librium crystallization of a melt close to the parent liquidcomposition (neglecting compaction-related removal ofinterstitial liquid) Indeed the composition of this C3k

layer is not significantly different from the compositions ofthe granite samples from the core of the plutons The dif-ferences correspond to locations either closer to the eutecticat PH2Ofrac1410 kbar (sample 2) or shifted toward the Or orAb components (sample 4) or toward the 5 kbar eutectic(sample 3) Assuming that the parent melt compositionwas constant from one pluton to another this may suggestthat (1) parent melts might be close to eutectic liquidspotentially formed at pressures around 10 kbar and(2) that various proportions of eutectic residual melt wereexpelled from the cumulate or local accumulation of feld-spar occurred in agreement with textural observationsIf it is accepted that the bulk initial liquids were close in

composition to the Ck layer it would appear that withthe exception of edenite and accessory phases the crystal-lization sequence was restricted to a small temperatureinterval (a few tens of degrees see Fig 15a and Scailletet al 2000)An alternative explanation for the observed mineral suc-

cession could be that it is the result of mechanical segrega-tion in a velocity gradient along the wall of the magmachamber Indeed the fact that the size of K-feldspar pheno-crysts is larger than that of both quartz and plagioclasethe latter being of comparable size could be taken as evi-dence in favour of the mechanical segregation hypothesisHowever assuming that the C3k layer has the compositionof the initial melt composition it may be appreciatedfrom the QzÂbÔr diagram (Fig 15) that mechanicalsubtraction of K-feldspar from the C3k composition shouldlead to Cq layers located far below the cotectic curveMoreover there is no reason why mechanical segregationshould lead to Cap and Cq layers with almost identicalthickness from one unit to another Lastly the zoning pat-tern of K-feldspar crystals implies closed-system conditionsof growth (at least for the periphery and overgrowth) asshownby the strong decrease in Ba contents In this respectthe distinct zoning patterns of K-feldspar cores (subhedraland regular) and edenite cores (disjointed with textural

AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75

Fig 9 (a) Composition of all the plagioclase crystals in the AbÔrÂn diagram showing the Na-rich composition of plagioclase (b) Variationin anorthite (mol ) across the plagioclase crystal shown in Fig 8a from the C1k layer



evidence of dissolution and regrowth) are striking andargue against common conditions during their crystalliza-tion In conclusion we consider that hydrodynamic sortingdoes not account for the structures textures and composi-tion of feldspars and quartzThe fact that edenite and other accessories (titanite

apatite and Fe^Ti oxides) are concentrated at the base ofeach rhythmic unit and that they show cores with specificmicrotextures suggests that they appeared early in thecrystallization sequence Experimental data at 3 kbarfor compositions similar to that of the Dolbel granite(DallrsquoAgnol et al 1999) show that the liquidus temperatureof amphibole in A-type granitic melts with 4^6wt H2Ois 800^8508C (and up to 9508C in dacite eg Prouteau ampScaillet 2003 Holtz et al 2004) temperatures significantlyhigher than those expected for Na-rich plagioclase crystal-lization at 5 kbar from liquids close to the eutectic(57008C) This raises the question of the origin of edeniteand the accessory minerals did they crystallize in situ or

were they brought up with the magma to the site of empla-cement This will be dealt with in the next sectionA further point of note in the layered series is that

amphibole crystallized before clinopyroxene the latteroccurring only as rare crystals in and above the Cq layersExperimental data for metaluminous A-type granites at3 kbar and reduced conditions (DallrsquoAgnol et al 1999)show that amphibole crystallizes before clinopyroxene attemperature around 8008C and that for melt water con-tents of 4^5 wt clinopyroxene starts to crystallize below7008C Moreover XFe values of clinopyroxene (017^036)obtained in that experimental study may be higher thanthose of amphibole (020^071) and are comparable withthe values found in the Dolbel granite samples (023^035for clinopyroxene 045^055 for edenite)Finally the overall stability of the magnetite thorn

titanitethornquartz assemblage in the Dolbel granites alongwith evidence for the presence of ilmenite preserved asinclusions in titanite suggest that variations in oxygen

200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)

Fig 10 Ba and Sr compositional profiles (ppm) in plagioclase crystals from (a) the C1k and (b) the C2p layers



fugacity occurred related to either cooling or to a changein redox conditions The abrupt decrease in Fe3thorn contentin amphibole (and correlative increase in Altot) from theC3q layer upwards would also support a change in fO2

conditions under which edenite crystallized

Significance of microtextures andchemical gradients in mineralsThe systematic presence of very thin oscillatory zoningin amphibole feldspars and titanite indicates that initialcompositions related to crystallization are preservedRetrogression of amphibole to actinolite ( epidote) isprobably related to subsolidus hydrothermal transforma-tion of limited extent such that the majority of magmatic

amphibole is preserved In the same way alteration ofboth plagioclase and K-feldspar is limited to the presenceof microporosity and of small white mica flakes We cantherefore consider that the variations in major and traceelement concentrations are dominated by primary featuresthat are related to crystal^melt partitioning during crystal-lization Microtextures and chemical variations in amphi-bole titanite and the feldspars allow four main stages to bedistinguished during the development of a given layeredsequence (Fig 16)

Stage 1 crystallization in a convecting magma body

The first stage corresponds to the growth of edenite andtitanite cores (the earliest phases to crystallize) whichshow complex zoning with evidence of oscillatory growthdissolution overgrowth and grain aggregation (synneusis)Indeed the cores of edenite crystals show the systematicpresence of resorption surfaces a feature commonly asso-ciated with changes in the physical conditions andor meltcomposition caused by for example magma recharge(Nixon amp Pearce 1987 Ginibre et al 2002) XMg valuesare the highest in these parts of the crystals (Fig 6a) andsuggest crystallization from primary melts All of thesedata along with the high liquidus temperature of amphi-bole and titanite imply the movement of early formed crys-tals within hot primitive liquids inhibiting regular growthand leading to a complex succession of episodes involvingdissolution and growthTherefore it is likely that the coresof both edenite and titanite did not crystallize in situ butformed in open systems (high liquidcrystal ratio) andwere subsequently brought up with the magma to thesite of emplacement (Fig 16a) This raises the questionof the nature of the basal amphibole-rich Cap layersAvailable data lead us to suggest that the edenite coreswere mechanically aggregated by shear strain in a velocitygradient along the crystallized wall whereas the externalportions of the grains subsequently formed in situ

Stage 2 crystallization in boundary layers

The second stage of crystallization is inferred to haveoccurred in a thermal boundary layer This stage beginswith the growth of the peripheral region of crystals ofedenite and titanite and the crystallization of the plagio-clase cores as suggested by the common presence of thinand extremely regular oscillatory zoning mimicking euhe-dral crystal faces (Fig 16b)The presence of this oscillatoryzoning attributed to kinetic effects at the crystal^liquidinterface in multi-component systems (Alle gre et al 1981Putnis et al 1992) and the transition to this regime fromthe contorted and resorbed style of zoning observed in thecores of edenite and titanite clearly support a change froma dynamic to a calm physical environment between stages1 and 2 Furthermore in addition to textural argumentsgeochemical variations also support the idea that theexternal zones of edenite and the cores of plagioclase

12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)


C1 minus387x + 138 (R2 = 092)C2 minus387x + 137 (R2 = 099)C3 minus361x + 129 (R2 = 081)C4 minus406x + 132 (R2 = 092)

Short axis

00 010 020 030 040 050

5

L (cm)


Long axis

Fig 11 Plots of the logarithm of the density of crystals ln (n) vs sizeclass L showing crystal size distribution curves for plagioclaseshort and long axes from the four rhythmic units Slope interceptand correlation coefficient are also indicated for the significant classesin each unit The close parallelism of the CSD lines for the short axesshould be noted



precipitated at the same time For example the externalpart of the core of edenite is characterized by a decreasein XMg Ba Sr Ti V and concomitant increase in Ce(Fig 7) whereas the intermediate dark zone of titanite ischaracterized by a decrease in Al2O3 CaO and Sr withan associated increase in FeO and incompatible elementssuch as REE and Th (Fig 14) Although the transitionfrom the core to rim of titanite and edenite would appearto be concurrent with the onset of plagioclase crystalliza-tion we cannot exclude the possibility that edenite startedto grow in situ before plagioclase saturation occurred Onthe other hand the compositional variations recorded inboth edenite and titanite imply that interstitial liquid wasnot renewed during this phase of crystal growth This is afundamental observation precluding the simple mechani-cal segregation of already grown crystalsQuartz appears as a cumulus phase following plagio-

clase saturation (Fig 16c) The fact that the bulk composi-tion of the Cq layers is approximately cotectic may suggestthat crystallization went to completion in situ although

as noted above the original bulk Cq compositions mayhave been closer to the eutectic if a proportion of residualmelt has been removed by compaction However theoccurrence of interstitial K-feldspar together with quartzand plagioclase indicates that at least part of the residualmelt remained trapped within the cumulate

Stage 3 lsquoen massersquocrystallization in closed system

The third stage of crystallization corresponds to the forma-tion of the C3k layer in particular to the precipitation ofK-feldspar phenocrysts and the growth of edenite rims(partly intercumulus) and the peripheral parts of plagio-clase crystals (Fig 16d and e) The existence of layers withbulk cotectic compositions suggests that plagioclase crys-tallized before K-feldspar and this would appear to besupported by the fact that plagioclase may be found asinclusions within K-feldspar However the similarity inmicrotextures and trace element evolution in plagioclaseand K-feldspar implies that K-feldspar crystallizationdid not significantly post-date plagioclase saturation

10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore

Fig 12 (a) Composition of K-feldspar phenocrysts in the OrÂnÂb diagram (b) Histogram of distances separating any K-feldsparphenocryst from its nearest neighbours in the C1k C3k and C4k layers (c) Or and Ab compositional profiles in K-feldspar phenocryst of Fig 8d



The rims to amphibole crystals show a decrease in XMgwhereas K-feldspars show an important decrease in Baand Sr Overgrowths of feldspars have very low Ba and Srcontents These data indicate low liquidcrystal ratios andclosed-system conditions for crystallization The fact thatthe bulk composition of the C3k layer remains far fromthe eutectic implies that during this stage there was no sig-nificant melt segregation and that solidification occurredunder conditions close to those of equilibrium crystalliza-tion Textural relationships indicate that plagioclase andquartz were already in equilibrium with the melt beforethe onset of K-feldspar crystallization whereas its occur-rence as phenocrysts implies crystallization in a significantvolume of melt Moreover phase relationships in theQzÂbÔr system at 5 kbar show that the temperatureinterval for cotectic and eutectic crystallization wasrestricted to about 208C if not less This may thereforesuggest that the bulk of the liquid crystallized at eutecticconditions by lsquoen massersquo crystallization with little or noremoval of melt

Stage 4 compaction and crystallization in theresidual porosity

This last stage corresponds to compaction of the cumulateby the injection of a new magma batch (Fig 16f ) To a firstapproximation the volume of the intercumulus phases(measured to be 28 on average for the sample studiedhere) could correspond to the volume of residual melt leftafter inflation-related compaction Assuming that beforecompaction occurred a solid framework of melt fractionclose to or lower than 50 existed for deformation to beefficient (the rigid percolation threshold Vigneresse et al1996) we estimate that less than 20 of the original inter-cumulus melt might be expelled by the compaction pro-cess However it should be noted that removal of thismelt fraction cannot account for the low bulk REE con-tents (Fig 4) if we consider that the REE patterns ofA-type granites published by Collins et al (1982) are repre-sentative of the parent melt of the Dolbel granitesThis may suggest early fractionation of amphibole andtitanite in agreement with the fact that magmas were

2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

Fig 13 Ba and Sr compositional profiles (ppm) in K-feldspar phenocrysts (a) phenocryst from the C3k layer (Fig 8d) (b) phenocryst fromthe C1k layer



already saturated in these two phases when they arrived atthe level of emplacement Besides some plagioclase crys-tals (eg Fig 8a) show rims characterized by an increasein the An component followed by a subsequent decreasetowards the contact This reverse evolution of plagio-clase composition suggests the percolation of a hotter

more primitive liquid through the framework of crystalsconsistent with injection of a new magma batch corre-sponding to the transition between stages 3 and 4The arrival of a new batch of magma will also result in

the formation of a new rhythmic unit with aggregationof small edenite crystals and incipient crystallization of

280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)

Fig 14 Back-scattered electron images of accessory minerals (a) Crystal of titanite showing a complex dark core partially resorbed andsurrounded by a light rim (C1k layer) (b) Magnetite grains from the C3k layer (c) and (d) X-ray images for Fe and Ti respectively of thesame magnetite grains as in (b) showing the presence of small titanite grains around magnetite (e) Compositional profile across a crystal oftitanite from the C3a layer (major elements electron microprobe analyses in wt trace elements laser-ablation ICP-MS analyses in ppm)inset location of laser pits on the titanite Scale bar in (a) and (b) represents 50 mm



plagioclase (Fig 16g) Mechanical erosion induced byinjection of a new batch of magma seems limited in mostcases However the nature of the C2 rhythmic unit whichis incomplete (C2ap and C2q layers only) shows thatmechanical erosion may be important perhaps becausethe C3 liquid was emplaced when the C2 unit still con-tained a high proportion of interstitial liquid and wasmore easily eroded away

Implications for the magmaemplacement processThe rhythmic layering in the Dolbel pluton

The repeated succession of the three layers forming eachrhythmic unit and the compositional evolution of mineralphases can be interpreted simply in terms of fractionalcrystallization in boundary layers from a common parentmagma followed by lsquoen massersquo equilibrium crystallizationEach rhythmic unit may correspond to arrival of a freshmagma batch and their repeated succession may representcrystallization of pulsed recharges as the magma bodygrew This is corroborated by the plagioclase CSDs whichare identical from one unit to another implying a similarthermal evolution for each unit Moreover the fact thatcumulus plagioclase crystals in the Cap layers and quartzgrains in the Cq layers are of smaller average size at thebase of the relevant layer with a progressive increase in

size towards the top suggests that nucleation is favouredwith respect to growth at the base of each unit (highervalues of supercooling)This is consistent with the emplace-ment of fresh magma batches at temperatures below theamphibole liquidus (ie 8508C) in contact with a eutecticmush (ie around 6508C) Nevertheless there is no clearmicrotextural evidence of grain resorption Accountingfor the systematic cotectic composition of the Cq layers fortheir constant thickness and for the zoning pattern of feld-spars the rhythmic units are unlikely to be formed only bycrystal segregation in a velocity gradient in a crystal-ladenmagma flowing along a rigid wall The variation in thick-ness for the Ck layers is a further important observationwhich may be also rationalized in terms of the hypothesisthat the growth of a rhythmic unit is arrested when a newmagma batch is injected in the chamber for temperature israised or at least held constant by the new batch of magmaThe variability in thickness of the Ck layers suggests that thefrequency of injections was erratic (assuming a constantheat flux) In conclusion we consider that the layered seriesof the g2 Dolbel pluton is an illustration of how fractionalcrystallization flow segregation and the assembly of sequen-tial magma injections interactAlthough the preservation of plagioclase CSD in each

unit and the extremely homogeneous distribution ofK-feldspar phenocrysts preclude hydrodynamic sorting

(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC

Porphyritic granites (pluton core)

Bulk chemical composition of the C2q C3q C1k and C3k layers

Cotectic curves and eutectic points at PH2O = 5 and 10 kbar

Cumulate compositions

ISC Instantaneous Solid Composition

range ofcotectic ISC

(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000

composition range ofmixtures of cotectic ISC

and eutectic liquids

Fig 15 (a) QzÂbÔr projection at PH2Ofrac14 5 kbar from Johannes amp Holtz (1996) (b) Plot of bulk compositions of the C1k C2q C3q and C3k

layers and of porphyritic granites from the pluton core in the QzÂbÔr diagram at PH2Ofrac14 5 kbar (also shown are the cotectic lines at 10 kbar)



C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q

plagioclase liquidus

plagioclase-quartz cotectic

plagioclase-quartz-K-feldspar eutectic

parent melt

differentiated interstitial melts

country rocks

q heat flux

rhythmic unit 1 next rhythmic unit

C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap

Fig 16 Sketches illustrating the main formation stages of the rhythmic units (not to scale) Clinopyroxene and accessory phases are notrepresented x xenocrystic grains entrained in the melt (a) Input of an amphibole-bearing and convecting magma batch with aggregationof amphibole (core) along the wall (b) Fractional crystallization under supercooling conditions with plagioclase crystallization (core) andamphibole growth (periphery) (c) Fractional crystallization with limited centimetre-scale melt movement amphibole and plagioclasegrowth (periphery) and crystallization of quartz (d) Equilibrium crystallization (no significant melt movement) with amphibole plagioclaseand quartz growth (periphery) and crystallization of K-feldspar (e) Continued crystallization (no significant melt movement) with amphiboleplagioclase quartz and K-feldspar growth (F505) (f) Input of a new magma batch inducing mechanical erosion and compaction (thorn meltremoval) of the former partially crystallized rhythmic unit (g) Crystallization of the new magma batch starting with segregation of amphibole(core) along the wall etc



several observations suggest that the system was at leasttemporarily dynamic (1) the textural characteristics ofthe edenite and titanite cores indicate that early flow seg-regation is likely to have occurred from magma batchesalready containing suspended crystals of edenite andaccessory minerals (2) the variable thickness of the Ck

layers including the absence of this layer in the C2 unitsuggests mechanical erosion by new magma pulses (3) thepresence of rare K-feldspar phenocrysts outside the Ck

layers indicates transport of suspended grains incorporatedin the crystallizing unit which could be derived fromeroded Ck layers elsewhere in the pluton Mobility of themelt therefore requires rather low viscosity values Wehave estimated the viscosities of the parent melt between650 and 8508C using the equation of Schulze et al (1996)and the bulk composition of the C3k layer Consideringmelt water contents ranging from 5wt at 8508C (theamount of water required for amphibole to crystallizebefore clinopyroxene) to 10wt (saturation value at6508C and 5 kbar Johannes amp Holtz 1996) leads to liquidviscosities of 1042 to 1044 Pa s values compatible with dif-ferential movement of melt and crystals

The place and role of deformation

Pons et al (1995) have shown that the deformation charac-terized by a cylindrical geometry with concentric fabricand shear zones is synchronous with the growth of thepluton and can be attributed to inflation caused by recur-rent magma replenishment In addition to a faint planarfabric and shear zones outlined by tiled plagioclase (seePons et al 1995 fig 8) deformation of the rhythmic unitsis also suggested by evidence of pressure dissolution atthe grain scale In the example shown in Fig 8a it isworth noting that dissolution of plagioclase post-dates thegrowth of its peripheral parts Furthermore we have seenthat the periphery of K-feldspar phenocrysts correspondsto intercumulus overgrowths and that they have very lowconcentrations in Ba and SrThis observation suggests thatdeformation-assisted compaction occurred after thegrowth of the periphery of plagioclase but before crystal-lization of the intercumulus overgrowths The proportionof intercumulus material in each rhythmic unit is esti-mated to be 25 suggesting that the intensity of defor-mation was limited with removal of the interstitial meltand compaction of the mush only to the particle lockingthreshold of Vigneresse et al (1996) On the whole thesimilarity in proportions of intercumulus material andCSD curves in the four units suggests that each unit wascompacted independently If compaction were to haveoccurred once several rhythmic units were in place theneach unit would be expected to have a distinct amount ofintercumulus material depending on how far crystalliza-tion had progressed in each layer and this is not the caseThe subsequent increments of deformation related to injec-tion of subsequent magma batches led to limited subsolidus

deformation (bent plagioclase twins sub-grains in quartz)with the exception of the pluton periphery where thisdeformation is much more pronounced (orthogneissi-fication) An additional question implicit to deformation-assisted melt removal is how melt escaped the solidframework There is no clear field evidence to determinewhether interstitial melt has left through the intercumuluspore space or via channel structures such as the conjugateshear zones Nevertheless the radial dykes of aplite in theoutermost zones of the plutons could represent such chan-nels through which the residual melts escaped Inflation-related compaction also accounts for the restricted natureof back reactions (growth of actinolite and epidote) andthe absence of chemical re-equilibration in mineralsduring cooling by removal of water-rich residual melts

Significance of K-feldspar accumulations in the pluton core

K-feldspars may be unevenly distributed and form localaccumulations in the core of the plutons (Fig 2b) Thisobservation contrasts with the very homogeneous distribu-tion found in the layered series which we interpret to bethe result of in situ crystallization This suggests that thepresence of K-feldspar accumulation in the pluton corerequires ssome additional process such as convection-related flow segregationWhole-rock compositions of somegranite samples from pluton cores (sample 4) appearshifted towards the Or end-member in the QzÂbÔr dia-gram (Fig 15b) In conclusion the distribution of mineralphases in the plutons especially of K-feldspar phenocrystsmay be an indicator of mass transfer within the plutons(ie of convection)

CONCLUSIONThis study shows that fractional crystallization in bound-ary layers (thermal and chemical gradients) is likely tooccur in some granitic plutons but remains limited toregions close to the wall-rock Nevertheless the bulk ofthe crystallization corresponds to lsquoen massersquo eutectic-typecrystallization Flow segregation remains of limitedextent and is restricted to the early stage of growth ofeach rhythmic unit The succession of rhythmic units isbasically ascribed to recurrent injection of fresh magmabatches which then crystallize and differentiate in situThis therefore fully corroborates the model of discontinu-ous magma input fed by a dyke (Clemens amp Mawer 1992Vigneresse amp Clemens 2000) This also shows that graniticmelt viscosities were low enough for differentiation andcrystal^melt segregation to occurA further point raised by our study is to what extent the

various rock units observed in silicic plutons may arisefrom in situ differentiation by fractional crystallizationWe show that the Ck layers (ie the major part of therhythmic units) result from the equilibrium crystallizationof a parent magma close to a eutectic composition



whereas only the Cap and Cq layers are likely to resultfrom fractional crystallization Thus the bulk of the meltsolidifies by lsquoen massersquo crystallization with little melt differ-entiation as the magma locks up rapidly This indicatesthat the large rock units occurring in most plutons rang-ing in composition from gabbro to granite are unlikely toresult from in situ differentiation by fractional crystalliza-tion of unique parent magmas as previously suggested(eg Cocherie et al 1994 Roberts et al 2000 Barbeyet al 2001)The Dolbel layered series probably represent an end-

member situation in which fractional crystallization in aboundary layer and closed-system equilibrium crystalliza-tion associated with recharge are the dominant processduring consolidation At the opposite end of the spectrumcalc-alkaline plutons occurring commonly as mafic andsilicic layered intrusions (Wiebe amp Collins 1998) probablyrepresent another end-member situation in which therecord of local crystallization processes has been largelywiped out by hydrodynamic processes related to episodesof mafic magma recharge (Pons et al 2006) Constructionof a pluton is not a unique process simply involving inter-mittent magma input but involves the combination of sev-eral processes which may be more or less predominantdepending on the context of emplacement and the magmacomposition Therefore the point is not to know whetherfractional crystallization occurs or not in silicic magmabodies but rather to what extent it is blurred or impededby other processes especially those related to hydro-dynamicsWe suggest that there is not a unique process ofconstruction of silicic plutons but that there are variousmechanisms (eg intermittent injection convection frac-tional crystallization deformation) which may becomepredominant in specific parts of plutons at specific periodsof time during pluton growth This does not precludehowever the existence of general trends for specificmagma types as for example in calc-alkaline plutonswhere mafic replenishments and density currents appearto be the rule

SUPPLEMENTARY DATASupplementary data for this paper can be found at Journalof Petrology online

ACKNOWLEDGEMENTSThanks are due to J Pons who gave us the igneous layer-ing sample from the Dolbel batholith and to A Kohlerand J Ravaux for assistance in scanning electron micros-copy and electron microprobe analyses We gratefullyacknowledge the detailed review comments by F BeaEW Sawyer R AWiebe and by MWilson the journaleditor This is CRPG Contribution 1917

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Aranguren A Larrea F J Carracedo M Cuevas J ampTubia J M (1997) The Los Pedroches batholith (southern Spain)polyphase interplay between shear zones in transtension andsetting of granites In Bouchez J L Hutton D H W ampStephensW E (eds) Granite From Segregation of Melt to Emplacement

Fabrics Dordrecht Kluwer Academic pp 215^229Barbey P Nachit H amp Pons J (2001) Magma-host interactions

during differentiation and emplacement of a shallow-level zonedgranitic pluton (Tarc ouate pluton Morocco) implications formagma emplacement Lithos 58 125^143

Barrie re M (1981) On curved laminae graded layers convectioncurrents and dynamic crystal sorting in the Ploumanacrsquoh(Brittany) subalkaline granite Contributions to Mineralogy and

Petrology 77 214^224Boher M AbouchamiW Michard A Albare de F amp Arndt N T

(1992) Crustal growth inWest Africa at 21Ga Journal of GeophysicalResearch 97 345^369

Boyce J W amp Hervig R L (2008) Magmatic degassing historiesfrom apatite volatile stratigraphy Geology 36 63^66

Carignan J Hild P Mecurren velle G Morel J amp Yeghicheyan D (2001)Routine analyses of trace elements in geological samples using flowinjection and low pressure on-line liquid chromatography coupled toICP-MS a study of referencematerials BR DR-NUB-N AN-GandGHGeostandardsNewsletter 25187^198

Cawthorn R G (1996) Layered Intrusions Amsterdam Elsevier531 pp

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Clemens J D amp Petford N (1999) Granitic melt viscosity and silicicmagma dynamics in contrasting tectonic setting Journal of the

Geological Society London 156 1057^1060Cocherie A Rossi Ph Fouillac A M amp Vidal Ph (1994)

Crust and mantle contribution to granite genesis An examplefrom the Variscan batholith of Corsica studied by trace elementand Nd^SrÔ isotope systematics Chemical Geology 115 173^211

Coleman D S Gray W amp Glazner A F (2004) Rethinking theemplacement and evolution of zoned plutons Geochronologic evi-dence for incremental assembly of the Tuolumne Intrusive SuiteCalifornia Geology 32 433^436

CollinsW J Beams S DWhite A J R amp Chappell BW (1982)Nature and origin of A-type granites with particular reference toSoutheastern Australia Contributions to Mineralogy and Petrology 80189^200

Couch S (2003) Experimental investigation of crystallizationkinetics in a haplogranite system American Mineralogist 881471^1485

DallrsquoAgnol R Scaillet B amp Pichavant M (1999) An experimentalstudy of a lower Proterozoic A-type granite from the easternAmazonian craton Brazil Journal of Petrology 40 1673^1698

Dowty E (1980) Crystal growth and nucleation theory and the num-erical simulation of igneous crystallization In Hargraves R B(ed) Physics of Magmatic Processes Princeton NJ PrincetonUniversity Press pp419^485

Droop GT R (1987) A general equation for estimating Fe3thorn concen-trations in ferromagnesian silicates and oxides from microprobe



analyses using stoichiometric criteria Mineralogical Magazine 51431^435

Ducheldquo ne S Pupier E Le Carlier de Veslud C amp Toplis M J(2008) A 3D reconstruction of plagioclase crystals in a syntheticbasalt American Mineralogist (in press)

Evensen N M Hamilton M J amp OrsquoNions R J (1978) Rare-earthabundances in chondritic meteorites Geochimica et Cosmochimica Acta42 1199^1212

Gibb F G F (1974) Supercooling and the crystallization ofplagioclase from a basaltic magma Mineralogical Magazine 39641^653

Ginibre C Kronz A amp Wolaquo rner G (2002) High-resolution quanti-tative imaging of plagioclase composition using accumulated back-scattered electron images new constraints on oscillatory zoningContributions to Mineralogy and Petrology 142 436^448

Glazner A F Bartley J M Coleman D S Gray W ampTaylor R Z (2004) Are plutons assembled over millions ofyears by amalgamation from small magma chambers GSAToday

14 4^11Higgins M D (1994) Numerical modelling of crystal shapes in

thin sections estimation of crystal habit and true size AmericanMineralogist 79 113^119

Higgins M D (2000) Measurement of crystal size distributionAmerican Mineralogist 85 1105^1116

Hodson M E (1998) The origin of igneous layering in the Nunarsuitsyenite South Greenland Mineralogical Magazine 62 9^27

Holtz F Sato H Lewis J Behrens H amp Nakada S (2004)Experimental petrology of the 1991^1995 Unzen dacite JapanPart I Phase relations phase composition and pre-eruptive condi-tions Journal of Petrology 46 319^337

Hunter R H (1987) Textural equilibrium in layered igneous rocksIn Parsons I (ed) Origins of Igneous Layering DordrechtD Reidel pp 473^503

Hutton D H W (1988) Granite emplacement mechanisms and tec-tonic controls inference from deformation studies Transactions ofthe Royal Society of Edinburgh Earth Sciences 79 245^255

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Petrology 23 127^162Irvine T N Andersen J C O amp Brooks C K (1998)

Included blocks (and blocks within blocks) in the Skaergaardintrusion Geologic relations and the origins of rhythmicmodally graded layers Geological Society of America Bulletin 1101398^1447

JangY D amp Naslund H R (2001) Major and trace element compo-sition of Skaergaard plagioclase Geochemical evidence for changesin magma dynamics during the final stage of crystallization of theSkaergaard intrusion Contributions to Mineralogy and Petrology 140441^457

JohannesW amp Holtz F (1996) Petrogenesis and Experimental Petrology ofGranitic Rocks Berlin Springer 335 pp

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Leake B EWoolley A R Arps C E S et al (1997) Nomenclatureof amphiboles Report of the Subcommittee on Amphiboles ofthe International Mineralogical Association Commission onNew Minerals and Mineral Names European Journal of Mineralogy

9 623^651Maale S (1976) Zoned plagioclase of the Skaergaard intrusion

East Greenland Journal of Petrology 17 398^419Machens E (1967) Notice explicative sur la carte gecurren ologique du Niger occiden-

tal Carte gecurren ologique a 1200 000e me Direction des Mines et de la

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Marsh B D (1998) On the interpretation of crystal size distributionsin magmatic systems Journal of Petrology 39 553^599

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Bulletin 112 119^135Milecurren si J P Feybesse J L Keita F Ledru P Dommanget A

Ouedraogo M F Marcoux E Prost A E Vinchon CSylvain J P Johan V Tegyey M Calvey J Y amp Lagny Ph(1989) Les minecurren ralisations aurife res de lrsquoAfrique de lrsquoOuest Leursrelations avec lrsquoecurren volution lithostructurale au Protecurren rozoilaquo que infecurren r-ieur Chronique des la Recherche Minie re 497 3^98

Morimoto N Fabrie s J Ferguson A K Ginzburg V Ross MSeifert S A amp Zussman J (1988) Nomenclature of pyroxenesBulletin de Minecurren ralogie 111 535^550

Morse S A (1980) Basalts and Phase Diagrams New York Springer493 pp

Naslund H R amp McBirney A R (1996) Mechanisms of formationof igneous layering In Cawthorn R G (ed) Layered IntrusionsAmsterdam Elsevier pp 1^43

Nixon G T amp Pearce T H (1987) Laser-interferometry studyof oscillatory zoning in plagioclase the record of magma mixingand phenocryst recycling in calc-alkaline magma chambersIztaccihuatl volcano Mexico American Mineralogist 72 1144^1162

Parsons I (ed) (1987) Origins of Igneous Layering NATO ASI Series666 pp

Parsons I amp Becker S (1987) Layering compaction and post-magmatic processes in the Klokken intrusion In Parsons I (ed)Origins of Igneous Layering NATOASI Series pp 29^92

Petford N Cruden A R McCaffrey M J W amp Vigneresse J L(2000) Granite magma formation transport and emplacement inthe Earthrsquos crust Nature 408 669^673

Pons J Barbey P Dupuis D amp Lecurren ger J M (1995) Mechanism ofpluton emplacement and structural evolution of a 21Ga juvenilecontinental crust The Birimian of Southwestern NigerPrecambrian Research 70 281^301

Pons J Barbey P Nachit H amp Burg J-P (2006) Development ofigneous layering during growth of pluton The Tarc ouateLaccolith (Morocco)Tectonophysics 413 271^286

Pouchou J L amp Pichoir F (1991) Quantitative analysis of homoge-neous or stratified microvolumes appying the model lsquoPAPrsquo InHeinrich K F J amp Newbury D E (eds) Electron Probe

Quantitation NewYork Plenum pp 31^75Prouteau G amp Scaillet B (2003) Experimental constraints on the

origin of the 1991 Pinatubo dacite Journal of Petrology 44 2203^2241Pupier E Ducheldquo ne S amp Toplis M J (2008) Experimental quantifi-

cation of plagioclase crystal size distribution during cooling ofa basaltic liquid Contributions to Mineralogy and Petrology 155 555^570

Putnis A Fernandez-Diaz L amp Prieto M (1992) Experimentallyproduced oscillatory zoning in the (Ba Sr)SO4 solid solutionNature 358 743^745

Roberts M P Pin C Clemens J D amp Paquette J L (2000)Petrogenesis of mafic and felsic plutonic rock associations thecalc-alkaline Quecurren rigut complex French Pyrenees Journal of

Petrology 41 809^844Sato H Holtz F Behrens H Botcharnikov R amp Nakada S

(2005) Experimental petrology of the 1991^1995 Unzen daciteJapan Part II ClOH partitioning between hornblende and melt



and its implications for the origin of oscillatory zoning of hornble-nde phenocrysts Journal of Petrology 46 339^354

Scaillet B Behrens H Schulze F amp Pichavant M (1996) Watercontents of felsic melts application to the rheological properties ofgranitic magmasTransactions of the Royal Society of Edinburgh EarthSciences 87 57^64

Scaillet B Holtz F amp Pichavant M (1997) Rheological propertiesof granitic magmas in their crystallization range InBouchez J L Hutton D H W amp Stephens W E (eds) GraniteFrom Segregation of Melt to Emplacement Fabrics Dordrecht KluwerAcademic pp 11^29

Scaillet B Holtz F amp Pichavant M (1998) Phase equilibrium con-straints on the viscosity of silicic magmas 1Volcanic^plutonic com-parison Journal of Geophysical Research 103 27257^27266

Scaillet B Whittington A Martel C Pichavant M amp Holtz F(2000) Phase equilibrium constraints on the viscosity of silicicmagmas II implications for mafic^silicic mixing processesTransactions of the Royal Society of Edinburgh Earth Sciences 91 61^72

Schmidt M W (1992) Amphibole composition in tonalite as afunction of pressure an experimental calibration of the Al-in-hornblende barometer Contributions to Mineralogy and Petrology

110 304^310Schulze F Behrens H Holtz F Roux J amp Johannes W (1996)

The influence of H2O on the viscosity of a haplogranitic liquidAmerican Mineralogist 81 1155^1165

Spera F J amp BohrsonW A (2001) Energy-constrained open-systemmagmatic processes I general model and energy-constrainedassimilation and fractional crystallization (EC-AFC) formulationJournal of Petrology 42 999^1018

Tait S R amp Jaupart C (1996) The production of chemically strati-fied and adcumulate plutonic igneous rocks Mineralogical Magazine

60 99^114Tegner C (1997) Iron in plagioclase as a monitor of the differentia-

tion of the Skaergaard intrusion Contributions to Mineralogy and

Petrology 128 45^51Tobisch O T McNulty B A amp Vernon R H (1997)

Microgranitoid enclave swarms in granitic plutons central SierraNevada California Lithos 40 321^339

Toplis M J Brown W L amp Pupier E (2008) Plagioclase inthe Skaergaard intrusion Part 1 Core and rim compositions inthe Layered Series Contributions to Mineralogy and Petrology 155329^340

Tsuchiyama A (1983) Crystallization kinetics in the systemCaMgSi2O6^CaAl2Si2O8 the delay in nucleation of diopside andanorthite American Mineralogist 68 687^698

Vigneresse J L amp Clemens J D 2000 Granitic magma ascent andemplacement neither diapirism nor neutral buoyancy InVendeville B Mart Y Vigneresse J L (eds) Slate Shale and

Igneous Diapirs in and around Europe Geological Society of London

Special Publication 174 pp 1^19Vigneresse J L Barbey P amp Cuney M (1996) Rheological transi-

tions during partial melting and crystallisation with applicationto felsic magma segregation and transfer Journal of Petrology 371579^1600

Wager L R amp Brown G M (1968) Layered Igneous Rocks EdinburghOliver amp Boyd 588 pp

Walker D Kirkpatrick R Longhi J amp Hays J F (1976)Crystallization history and origin of lunar picritic basalt sample12002 Phase-equilibria and cooling-rate studies Geological Society ofAmerica Bulletin 87 646^656

Weinberg R F Sial A N amp Pessoa R R (2001) Magma flowwithin the Tavares pluton northeastern Brazil compositional and

thermal convection Geological Society of America Bulletin 113508^520

Wiebe R A amp Collins W J (1998) Depositional features andstratigraphic sections in granitic plutons implications for theemplacement and crystallization of granitic magmas Journal of

Structural Geology 20 1273^1289Wiebe R A Blair K D Hawkins D P amp Sabine C P (2002)

Mafic injections in situ hybridization and crystal accumulation inthe Pyramid Peak granite California Geological Society of AmericaBulletin 114 909^920

Wiebe R A Jellinek M Markley M J Hawkins D P ampSnyder D (2007) Steep schlieren and associated enclaves in theVinalhaven granite Maine possible indicators for graniterheology Contributions to Mineralogy and Petrology 153 121^138

Witt-Eickschen G Seck H A Mezger K Eggins S M ampAltherr R (2003) Lithospheric mantle evolution beneath theEifel (Germany) constraints from Sr^Nd^Pb isotopes and traceelement abundances in spinel peridotite and pyroxenite xenolithsJournal of Petrology 44 1077^1095

Zak J amp Paterson S R (2005) Characteristics of internalcontacts in the Tuolumne Batholith central SierraNevada California (USA) Implications for episodicemplacement and physical processes in a continentalarc magma chamber Geological Society of America Bulletin 113976^995

Zellmer G F Blake S Vance D Hawkesworth C amp Turner S(1999) Plagioclase residence times at two island arc volcanoes(Kameni Islands Santorini and Soufriere St Vincent) deter-mined by Sr diffusion systematics Contributions to Mineralogy and

Petrology 136 345^357

APPENDIX ANALYTICALMETHODSWhole-rock major and trace element concentrations weredetermined by inductively coupled plasma atomic emissionspectrometry (ICP-AES) and ICP-MS (CRPG-CNRSNancy) respectively using HNO3 solutions prepared fromfused glass Sample preparation analytical conditions andlimits of detection have been described by Carignan et al(2001) Analytical uncertainties are given as 2 for majorelements and as 5 or 10 for trace element concentra-tions (except REE) higher or lower than 20 ppm respec-tively Precision for REE is estimated at 5 whenchondrite-normalized concentrations are410 ppm and at10 when they are lowerMajor element composition of minerals and Ba and

Sr concentration profiles of feldspars were determinedusing a CAMECA SX-50 electron microprobe (ServiceCommun de Micro-analyse Universitecurren Henri Poincarecurren Nancy) Operating conditions were (1) 10 nA sample cur-rent 15 kV accelerating potential counting times of 20 sand a beam diameter of 1 mm for major elements(2) 100 nA 15 kV 20 s and beam diameter of 1 mm for Srand Ba in feldspars Calibration was made on a combina-tion of silicates and oxides Data reductions were per-formed using the PAP correction procedure (Pouchou ampPichoir 1991) Ferric iron has been estimated according to



Leake et al (1997) for amphibole and Droop (1987) for theothers mineral phasesLaser-ablation ICP-MS analyses (with pit size diameters

of 10^40 mm) were performed on polished rock thin sec-tions at the Institute of Mineralogy and GeochemistryUniversity of Lausanne The measurements were acquiredwith a 193 nm Lambda Physik Excimer laser (Geolas200M system) coupled to a PerkinÊlmer 6100 DRCICP-MS system Laser settings were 27 kV and 10Hzrepetition rate yielding a fluence of about 12 Jcm2 on theablation site Helium was used as carrier gas (11lmn)We chose NIST612 glass as external standard and Caand Al as internal standards for amphibole and titaniterespectively (on the basis of electron microprobe mea-surements on the ablation pit sites) BCR2 basalticglass was used as a monitor to check for reproducibilityand accuracy of the system Results were within 10of the values reported by Witt-Eickschen et al (2003)Data reduction was done using LAMTRACE a

spreadsheet developed by S E Jackson (MacquarieUniversity Sydney)Ion microprobe analyses were made on a Cameca IMS

3f ion microprobe (CRPG-CNRS Nancy) A 10 kV O^

primary beam of 15^20 nA intensity was focused to a spotof 20 mm in diameter Secondary ions were accelerated to4500 eV and analysed at a mass resolution of 500 withan energy filtering at ^8010V The background 30Si86Sr 88Sr 137Ba and 138Ba were measured by peak switch-ing with counting times of 3 s on each peak Successivemeasurements were cumulated for 15min on each sampleposition Secondary ion currents are normalized to Siand secondary yields relative to Si determined on threestandard glasses (NBS 614 BHVO BCR2G) rangingin composition from 499 to 720wt There is noobservable variation of the relative secondary yields ofSr and Ba for these standards implying that the calibra-tion is not dependent on the chemical composition ofsilicate samples



structural characteristics of granitic plutons (Spera ampBohrson 2001 Pons et al 2006) and consideration of addi-tional processes is required Although many processes havebeen proposed to occur in magma chambers during theformation of granitic plutons (Barrie re 1981 Parsons ampBecker 1987 Tobisch et al 1997 Hodson 1998 Wiebe ampCollins 1998 Wiebe et al 2002 Pons et al 2006) theirexact role and relative importance remain open to debateas illustrated for example by contrasting opinions con-cerning the origin of the Tuolumne Batholith in centralSierra Nevada (Glazner et al 2004 Zak amp Paterson2005) The aim of the present study is to reassess therole of processes that occur in magma chambers duringthe formation of granitic plutons with emphasis onthe role of fractional crystallization in boundary layers(ie in temperature and compositional gradients) and itsinterplay with new magma injection and inflation-relateddeformation during pluton growth and solidificationEven though the physical properties of basaltic and

granitic magmas are different the study of mafic igneouscomplexes provides insight into the magmatic processesoccurring during the construction of magma chambers inthe crust For example compositionally zoned minerals incumulate rocks are commonly interpreted in terms of thedegree of local melt differentiation and such chemical gra-dients can be used to constrain liquid evolution and resi-dence times (eg Maale 1976 Tegner 1997 Markl ampWhite 1999 Zellmer et al 1999 Jang amp Naslund 2001Boyce amp Hervig 2008 Toplis et al 2008) Similarlyunzoned crystals typical of adcumulate textures are inter-preted to be the result of small-scale convection in liquidsor diffusion leading to the progressive removal of intersti-tial porosity with little or no mineralogical and composi-tional variation relative to the cumulus assemblage (egMorse 1980 Hunter 1987 Tait amp Jaupart 1996) At longerlength scales modally graded layered sequences andlsquoturbidite-likersquo structures have been related to fractionalcrystallization in boundary layers and to crystal sortingand accumulation through density currents and large-scale convection (eg Wager amp Brown 1968 Morse 1980Parsons 1987 Cawthorn 1996 Irvine et al 1998)Returning to the case of more silicic and alkaline mag-

matic rocks noteworthy examples of igneous layering arewell known in syenite and granite plutons with rhythmicunits mineral grading cross-stratification and troughlayering (Wager amp Brown 1968 Barrie re 1981 Parsons1987 Parsons amp Becker 1987 Cawthorn 1996 Tobischet al 1997 Hodson 1998) These structures suggest thathydrodynamic sorting and thermal convection are alsolikely to occur in granitic plutons at least at the scaleof a single magmatic unit (Wiebe amp Collins 1998Weinberg et al 2001 Wiebe et al 2002 Pons et al 2006)Furthermore recent experimental and numerical studieshave shown that the viscosities of silicic magmas cluster

around 1045 Pa s and do not change significantly as longas the crystal fraction remains below 30^50 (Scailletet al 1996 1997 1998 Clemens amp Petford 1999) These vis-cosity values are lower than formerly considered thus itwould appear that viscosity is not an obstacle to convec-tion in silicic magma chambers (even though length andtime scales are likely to be different from those encoun-tered in mafic chambers) nor should it impede smallscale crystal^melt segregation Therefore the study ofigneous layering in granitic bodies may provide us withinformation on the role of magma chamber processesccedilespecially fractional crystallization in boundary layersccedilduring the construction of granitic plutonsThe assessment of the role of crystallization in a thermal

boundary layer requires careful choice of rock samplesFor example (1) layering formed by crystal settling andhydrodynamic sorting should be avoided as much as possi-ble and this restricts sampling to near-vertical layeringclose to the walls of plutons (2) deformation gradientsrelated to pluton inflation need to be moderate for theigneous textures to be preserved (3) bulk compositionsshould be close to experimentally determined phase dia-grams to have an appropriate reference frame (4) mineralphases should display chemical zoning allowing the extentof melt differentiation to be assessed In the light of theseconstraints the Dolbel batholith in SW Niger has beenselected for this study as it fulfils all of the above criteriaAfter a presentation of the plutons and their structural fea-tures we describe the microtextures and compositions ofthe main mineral phases and then discuss the developmentof the compositional layering during the course of plutongrowth with particular emphasis on fractional crystalliza-tion in boundary layers

GEOLOGICAL SETT INGThe Dolbel batholith (Liptako province SW NigerMachens 1967 Pons et al 1995) is located in the northeast-ern part of the Leo Rise (Fig 1a) an extensive 21Gagranite^greenstone terrane considered to be a major zoneof crustal growth (Milecurren si et al1989 Abouchami et al1990Boher et al 1992) The batholith consists of 14 kilometre-sized plutons forming a narrow NW^SE-trending beltperpendicular to the regional strike of the surroundinggreenstones (Fig 1b) The shape of the plutons deflectionof the country-rock schistosity and crosscutting relation-ships show that plutons were emplaced syntectonicallyin a northward-trending succession (g1 to g14) The smallsize of the plutons and their distribution along a NW^SElinear array parallel to the direction of regional shorteningwere considered by Pons et al (1995) to result from pulsedmagma ascent and ponding controlled by regional defor-mation that created a series of large tension gashes parallelto the 1 direction







γ granite plutons

greenstones

dune

radial dykes



γ14

14deg30prime

1deg20prime

1deg20prime

Dolbel

γ13

γ12

γ10 γ9 γ7

γ5

γ2

γ1

γ3

γ4

γ6γ8

γ11

0 1 2 kmN

2deg

13deg

14deg

Sirba

Torodi

DargolDoundielTera

Bellekoire

Dolbel Niger

Darbani

1deg

BU

RK

INA

FASO

500 km


NIAMEY

DOLBELBATHOLITH

sedimentary cover

Gotheye

2deg

LeoRise

(a)

(b)

track

lineation

Ayorou







(a)

(c)

(d)

(e)

(b)

Kfs

Kfs

Kfs

Kfs





















C1


C2 C3 C4

Pluton centre

2 cm


base of theC3 layer

top of theC3 layer














g2 pluton)





























SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006


pluton core



100

1000










rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap











































































































































γ granite plutons

greenstones

dune

radial dykes



γ14

14deg30prime

1deg20prime

1deg20prime

Dolbel

γ13

γ12

γ10 γ9 γ7

γ5

γ2

γ1

γ3

γ4

γ6γ8

γ11

0 1 2 kmN

2deg

13deg

14deg

Sirba

Torodi

DargolDoundielTera

Bellekoire

Dolbel Niger

Darbani

1deg

BU

RK

INA

FASO

500 km


NIAMEY

DOLBELBATHOLITH

sedimentary cover

Gotheye

2deg

LeoRise

(a)

(b)

track

lineation

Ayorou







(a)

(c)

(d)

(e)

(b)

Kfs

Kfs

Kfs

Kfs





















C1


C2 C3 C4

Pluton centre

2 cm


base of theC3 layer

top of theC3 layer














g2 pluton)





























SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006


pluton core



100

1000










rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap










































































































































(a)

(c)

(d)

(e)

(b)

Kfs

Kfs

Kfs

Kfs





















C1


C2 C3 C4

Pluton centre

2 cm


base of theC3 layer

top of theC3 layer














g2 pluton)





























SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006


pluton core



100

1000










rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap
























































































































































C1


C2 C3 C4

Pluton centre

2 cm


base of theC3 layer

top of theC3 layer














g2 pluton)





























SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006


pluton core



100

1000










rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap

















































































































































g2 pluton)





























SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006


pluton core



100

1000










rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap

















































































































































SiO2 6660 6902 7132 6917 6915 6895 6864 6889

Al2O3 1486 1473 1489 1443 1254 1267 1486 1524

FeOtot 295 195 175 131 424 460 271 244

MnO 007 003 003 003 007 008 005 004

MgO 156 055 042 045 146 161 094 077

CaO 310 163 146 167 293 329 297 183

Na2O 606 591 573 612 547 531 586 557

K2O 297 317 332 386 127 141 263 306

TiO2 027 018 014 009 044 047 029 027

P2O5 021 010 010 012 011 012 007 007

LOI 090 086 079 092 121 157 122 072

Total 9956 9813 9994 9817 9889 10007 10024 9890

Ba 1648 1920 1872 2708 592 707 1573 2122

Co 7 mdash 5 6 11 12 7 6

Cr 55 8 8 20 14 15 9 8

Ni 25 9 14 18 11 12 8 7

Rb 55 85 77 51 29 30 57 64

Sr 1316 1428 1540 773 1101 1310 1491 1465

V 44 39 29 14 83 94 56 45

Y 8 6 4 4 8 8 5 4

Zn 68 61 60 51 126 135 79 68

Zr 81 68 71 57 152 151 93 84

La 73 25 40 14 534 575 376 253

Ce 207 87 125 69 1298 1342 844 716

Nd 79 36 41 19 844 849 540 390

Sm 20 12 12 07 226 224 141 109

Eu 06 05 05 050 075 079 066 061

Gd 13 08 09 09 186 189 124 090

Dy 11 06 07 06 142 144 093 072

Er 07 04 04 03 076 075 050 038

Yb 07 04 04 04 074 074 050 039

Lu 01 01 01 01 011 012 007 006


pluton core



100

1000










rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap













































































































































rhythmic unit



SiO2 4205 5412 5169 6667 6428 000 3028 3603

TiO2 108 000 007 1874 000 3819 000

Al2O3 997 029 093 2102 000 123 1996

Cr2O3 001 001

Fe2O3tot 087 1914

FeOtot 1270 015 000 9300

Fe2O3calc 000 152 291 6893

FeOcalc 2256 1367 1008 3097

MnO 036 058 041 002 008 014

MgO 784 1497 986 002 002 000 002 003

CaO 992 1252 2177 154 000 2803 2177

Na2O 229 019 127 1054 028 002

K2O 177 004 004 1676 007

H2Ocalc 193 206 113 174

Total 9978 9995 9901 9998 10008 9993 9992 9882

Si 653 786 198 292 298 000 400 300

Aliv 147 005 002

Alvi 035 000 002

Altot 109 102 000 019 196

Ti 013 000 000 000 379 000

Fe3thorn 000 017 013 000 000 200 008 108

Fe2thorn 293 166 028 100

Mn 005 007 001 000 001 001

Mg 181 324 056 000 000 000

Ca 165 195 090 007 000 397 194

Na 069 005 010 090 003 000 000

K 035 001 000 099 001 000P

cations 1595 1506 400 498 502 300 1205 799

O 230 230 60 80 80 40 125


Ab 923 25

An 74 00

Or 02 975









(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap












































































































































(a)

(d)

(b)

(c)

(e)

1

1

2 3 4

4 7 10 121613

5

act

act

ep

ep

ep

ed

ed

eded

ed

ed

act

pl

tit




1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap







































































































































1

0 2 4 6

2 3 4 5

con

tent

(ap

fu)

25

15

05

20

10

XMg

Altot

Ca

Si3

(e)

d (microm)

(f)

Al to

t (a

pfu)

Si (apfu)62 64 66 68 70 72

23

19

15

11

07

(c)12

16

20

24

25 65 105 145

C4 C3

C3q C3ap

C2 C1


Fe2+

(apf

u)

actinolite

725 70 65675 625

7577 7678 7479030

070

060

050

040

edenite

ferro-edenite

ferro-actinolite

pargasite

ferropargasite

Mg

(Mg

+ F

e2+)

030

070

060

050

040Mg

(Mg

+ F

e2+)

Si (apfu)

Si (apfu)

Mg-hbl

Fe-hbl


Pluton core

(a)

(b)

20

16

22 24 26

24

28

28

30Fe2+ (apfu)

Mg2+

(ap

fu)

C3q to C4k

C1k to C3ap

)

) (d)

C3q to C4k

C1k to C3ap

)

)rim





PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap








































































































































PREE are rela-









400

300

200

100

conc

entr

atio

n (p

pm)

900

300

700

500

conc

entr

atio

n (p

pm)

30

20

10

200 300 4000 100

d (microm)

conc

entr

atio

n (p

pm)

616

1472

7955

Sr

Ba

V

Ti20

Ce

Zr2

(b)

(c)

(d)

040

060

020

XM

g

XMg

patchycore

lightrim


(a)

4

1

10

12

13

16









(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap












































































































































(a) (c)

(b) (d)









AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap












































































































































AnAb

Or

Plagioclase

AnAb

Or

(a)

100 200 300

20

40

60

80

100

mol

e

Ano

rthi

te

550 800 1050 1550 1800 20501300 2300 2550

(b) corerim

An75









200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap












































































































































200

400

600

800

1400

1000

1200

200

400

600

800

1400

1000

1200

100 200 300 550 1050 1550 2050 2550

500

600

200

1000

1400

1000

1000

1500

2000

2500

1500

100 200 300 550 1050 1550 2050 2550

Baco

ncen

trat

ion

(ppm

)co

ncen

trat

ion

(ppm

)Sr

Ba Sr

(a)

(b)

d (microm)500 1000 1500

d (microm)












12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap















































































































































12

11

10

9

8

7

6

11

10

9

8

7

6

00500 010 015 020 025 030

Ln (

n)Ln

(n)



Short axis

00 010 020 030 040 050

5

L (cm)


Long axis









10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap












































































































































10

10 15 20 25 30

50

30

70

90

N

C1k

C3k

C4k

An

Or

K-feldspar

An

AbOr

(a)

0 020001000 3000 4000

94

96

98

2

4

8

6

Or Ab

d (microm)

Mol

e

20001000 3000 4000

d (microm)

(c)

(b)

over

grow

th

over

grow

th

perip

hery

perip

hery

Ab

core

over

g

per

percore







2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap










































































































































2

4

6

8

10

12

14

16

18

20001000 3000 4000 20001000 3000 4000

2

3

4

5

Con

cent

ratio

ns (

103

ppm

)C

once

ntra

tions

(10

3 pp

m)

Ba Sr

(a)

5

10

15

20

25

20001000 3000 4000

2

3

4

Ba Sr

d (microm)20001000 3000 4000

d (microm)

(b)

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore

over

grow

th

perip

hery

perip

herycore







280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap










































































































































280

290

270

30

20

10

800

700

600

500lightcore

lightrim

lightrim

darkzone

darkzone

lightcore

lightrim

lightrim

darkzone

darkzone

25

15

05

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

Th

4000

2000

1000

500

3000

ΣREE

400

300

200

100

0

V

Sr

CaO

FeOtot

Al2O3

(e)

Ti Fe

1

6

12

(a) (b)

(c) (d)









(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap












































































































































(b)

10 20

20

30 40

40

50

C3k (bulk)

C1k (bulk)

C3q (bulk)

C2q (bulk)

Ab

Qz

Or

1

3

4

liquidus ISC

eutecticISC







(a)

700

60 804020

80

60

40

20

1070degQz

OrAb

P = 5 kbaH2O = 1

876deg758deg

700 760

800

900

700

1000







C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap







































































































































C1ap

q

q

(a)

C1qC1ap

(c)q

q

C1ap

(b)q

q

C1q C1kC1ap

(d)q

q




parent melt


country rocks

q heat flux


C1q C1k C2ap

x

(f)q

q

C1q C1k

(e)q

q


C1q C1k C2ap

x(g)q

q

amphibole

plagioclase

quartz

K-feldspar

C1ap

C1ap

C1ap







































































































































igneous layering, fractional crystallization and growth of granitic

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