research article magmatism in the asunción-sapucai...

Hindawi Publishing CorporationJournal of Geological ResearchVolume 2013 Article ID 590835 22 pageshttpdxdoiorg1011552013590835

Research ArticleMagmatism in the Asuncioacuten-Sapucai-Villarrica Graben(Eastern Paraguay) Revisited Petrological GeophysicalGeochemical and Geodynamic Inferences

Piero Comin-Chiaramonti1 Angelo De Min1 Aldo Cundari2 Vicente A V Girardi3

Marcia Ernesto4 Celso B Gomes3 and Claudio Riccomini3

1 Mathematics and Geosciences Department Trieste University Via Weiss 8 34127 Trieste Italy2 Geotrack International 37 Melville Road Brunswick West Melbourne VIC 3055 Australia3 Geosciences Institute University of Sao Paulo Cidade Universitaria Rua do Lago 562 05508-900 Sao Paulo SP Brazil4 Astronomical and Geophysical Institute (IAG) of the Sao Paulo University Rua do Matao 1226 05508-090 Sao Paulo SP Brazil

Correspondence should be addressed to Piero Comin-Chiaramonti cominunitsit

Received 12 November 2012 Revised 25 March 2013 Accepted 8 April 2013

Academic Editor David T A Symons

Copyright copy 2013 Piero Comin-Chiaramonti et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

The Asuncion-Sapucai-Villarrica graben (ASV) in Eastern Paraguay at the westernmost part of the Parana Basin was the siteof intense magmatic activity in Mesozoic and Tertiary times Geological petrological mineralogical and geochemical resultsindicate that the following magmatic events are dominant in the area (1) tholeiitic basalt and basaltic andesites flows and sillsof low- and high-titanium types (2) K-alkaline magmatism where two suites are distinguished that is basanite to phonolite andalkali basalt to trachyte and their intrusive analogues (3) ankaratrite to phonolite with strong Na-alkaline affinity where mantlexenoliths in ultramafic rocks are high- and low-potassium suites respectivelyThe structural and geophysical data show extensionalcharacteristics for ASV On the whole the geochemical features imply different mantle sources consistently with Sr-Nd isotopesthat are Rb-Nd enriched and depleted for the potassic and sodic rocks respectively Nd model ages suggest that some notionaldistinct ldquometasomatic eventsrdquo may have occurred during Paleoproterozoic to Neoproterozoic times as precursor to the alkaline andtholeiitic magmas It seems therefore that the genesis of the ASVmagmatism is dominated by a lithospheric mantle characterizedby small-scale heterogeneity

1 Introduction

Velazquez et al [1] presented a structural analysis of thecentral segment of the ldquoAsuncion Riftrdquo mainly based on theprevious papers related to the Eastern Paraguay magmatismin general and to the Asuncion-Sapucai-Villarrica graben(ASV) in particular and also based on extensive field datacollected earlier on the dyke swarms cropping out in the areaHowever some aspects as for example the close associationin space of potassic and sodic alkaline rock-types withtholeiitic dykes and flows (both of high- and low-Ti types cf[2]) have not been discussed in detail by the above authors

This paper focuses on general aspects of the magmatismfrom the western margin of the Parana-Angola-Etendeka

system (PAE) where tholeiitic flows and dykes (Early Cre-taceous both of high-Ti and low-Ti types cf Figure 1(a)and [3]) are associated in time and space with a widevariety of alkaline rock-types (both potassic and sodic) andcarbonatites

The investigated alkaline and tholeiitic rocks from East-ern Paraguay span in age mainly from Early Cretaceousto Paleogene times Therefore they are germane to themagmatic and tectonic evolution of the PAE and of theAtlantic Ocean (cf Figure 1(b) and [4 5])

This review aims at discussing (1) the relationshipsbetween tectonics and magmatic activity on the basis offield and geophysical data (2) a detailed description of thegeological characteristics of the Asuncion-Sapucai-Villarrica

2 Journal of Geological Research

SouthAmerica

EPAsuncion

Low Ti

Africa

SouthAtlantic

Dykes

High Ti

Rio de Janeiro

(a)

Moccedilamedes Arch

50∘ W

10∘ S

20∘ S

30∘ S

40∘ W 20∘W

10∘S

20∘S

BrazilAraguaia-Paranaıba-

Cabo Frio

Ponta Grossa ArchRio PiquirıTorres SynclineRio Grande Arch

RioGrande

RiseWalvis

Ridge

Angola

Damara Belt

Namibia

Relative motion

as from flow lines

South America

absolute motion

Africa

abso

lute m

otion

MAR motion

(b)

Figure 1 (a) Sketch map of the Parana-Angola-Etendeka system [3] where the arrows indicate the occurrences of the main dyke swarmsThe basaltic lavas are subdivided into broad high- and low-Ti groups and late-stage rhyolites (yellow fields) EP Eastern Paraguay (b) Mainlineaments in the Parana-Angola-Etendeka system (PAE) western Gondwana at ca 110Ma (modified after [6]) corresponding to the mainlineaments of the alkaline and alkaline-carbonatitic complex Inset vector diagram showing relationships among absolute plate motionsrelative motions and motion of the Mid-Atlantic Ridge (MAR after [7])

(ASV) graben (3) petrography and petrochemistry of themagmatic rock-types (and the associated mantle xenoliths)from ASV (4) the most important geochemical and Sr-Ndisotopic features of the magmatism (5) the petrogenesis andgeodynamic implications

2 Eastern Paraguay Geological Outlines andGeophysical Aspects

Eastern Paraguay shows a complex block-faulted structurebetween the southern Precambrian tip of the AmazonianCraton (Apa block) and the northern one of the Rio de laPlata Craton (Caacupu high Figure 2) This intercratonicarea including the westernmost fringe of the Parana Basin(PB) represents an undeformed basin along the westernGondwana (Figure 1) where the sedimentation started inCambrian times was topped by Early Cretaceous tholeiiticbasalts of the Serra Geral Formation [8 9] and followed byyounger sedimentation (Figure 2)

Moreover it should be also noted that Eastern Paraguaylies along the former western margin of the Gondwanabounded by an anticlinal structure established since EarlyPaleozoic the Asuncion Arch which separates the ParanaBasin (East) from the Gran Chaco Basin (West) [10] PBshows a high-velocity upper mantle ldquolidrdquo with a maximumS-wave velocity of 47 kms (Moho 37 km depth) with anunresolved low-velocity zone to a depth of at least 200 km [11]Between the two blocks that is Apa andCaacupu of Figure 2Eastern Paraguay was subjected to NE-SW-trending crustalextension during Late Jurassic-Early Cretaceous probablyrelated to the western Gondwana breakup (Figure 1 [10 12]

and therein references) NW-SE trending faults parallelingthe dominant orientation of Mesozoic alkaline and tholeiiticdykes reflect this type of structure [13 14]

From the aeromagnetic survey [15 16] the linear mag-netic anomalies trend mainly N40-45W (Figure 3) Theseanomalies have been interpreted as resulting from EarlyCretaceous tholeiitic dyke swarms [16] but field evidencedoes not support this hypothesis Most magnetic anomaliescorrespond to older Precambrian tectonic lineament [17]The Landsat lineaments trending mainly NE and EW maytherefore reflect tectonic lineaments from the basement [18]

The Bouguer gravity map (Figure 3) consists of prevail-ing NW-trending gravity ldquohighsrdquo and ldquolowsrdquo that representshallow to exposed basement and sedimentary basins respec-tively [19]The boundaries between gravity highs and lows aregenerally marked by step gradients that may reflect abruptbasement offsets along faults or basement dip changes bycrustal warping Notably the gravity lows and highs parallelthe dominant NW attitude of the magnetic lineaments withpost-Palaeozoic magmatism (both tholeiitic and alkaline)associated with gravity lows Therefore the ASV representsthe most important geological structure of the region (seelater)

Notably the present seismic activity (earthquakes withhypocenters lt70 km) indicates that the NW-trending faultsystems continue up to present day that is the Pilcomayolineament (inset of Figure 3) also aligned with the Piquirılineament and the Torres syncline (Figure 1(b))

In conclusion the resulting structural pattern con-trolled the development of grabens or semigrabens as aresponse to NE-SW-directed extension and continued evolv-ing into Cenozoic times [12 24] According to Tommasi and

Journal of Geological Research 3

Fuerte Olimpo1341

Alto Paraguay241

Rio Apa139

22∘S

26∘S

55∘W57 ∘W

Valle-mıApa river

Apablock Amambay

Cerro Chiriguelo139

Cerro Sarambı

San Carlos 1341

Pedro Juan Caballero

BrazilJejui-Aguaray-Guazufault system

Gran

Cha

coBa

sin San Pedro low

Paraguay

Asuncion

Asuncion

58Pilcomayo river

Argentin

a

ASV

Central 130-127

acutehigh

Asuncion-Encarnacion fault system

132

SJB

Misiones 118Parana riverPa

ragu

ay ri

ver

100 kmArgentina

Para

na B

asin

Encarnacion 133

Ciudad delEste133

Para

na B

asin

1

2

3

4

5

6

7

8

9

10

11

12

13

14

SJB

Caacup998400e

Figure 2 Geological sketchmap of Eastern Paraguay (modified after [10 13 20ndash24]) ASV Asuncion-Sapucai-Villarrica graben (1) Neogeneand Paleogene sedimentary cover (eg Gran Chaco) (2) Paleogene sodic alkaline rocks Asuncion Province (3) Late-Early Cretaceoussodic alkaline rocks (Misiones Province San Juan Bautista SJB) (4) Early Cretaceous potassic alkaline rocks (posttholeiites ASU Asuncion-Sapucai-Villarica graben Central Province) (5) Early Cretaceous tholeiites of the Parana Basin (Serra Geral Formation in Brazil and AltoParana Formation in Paraguay cf [4]) (6) Early Cretaceous potassic alkaline rocks (pretholeiites Apa and Amambay Provinces) (7)Jurassic-Cretaceous sedimentary rocks (Misiones Formation) (8) Permo-Triassic alkaline rocks (Alto Paraguay Province) (9) Permiansedimentary rocks (IndependenciaGroup) (10) Permo-Carboniferous sedimentary rocks (CoronelOviedoGroup) (11) Ordovician-Siluriansedimentary rocks (Caacupe and Itacurubı Groups) (12) Cambro-Ordovician platform carbonates (Itacupumı Group) (13) Archean toEarly Paleozoic crystalline basement high- to low-grade metasedimentary rocks metarhyolites and granitic intrusions (14) major tectoniclineaments and faultsThe radiometric values for example 133Ma are referred to 40Ar39Ar plateau ages for themainmagmatic types [25ndash27]and to RbSr ages for the Precambrian rhyolitic rocks of Fuerte Olimpo and Fuerte San Carlos [28]


55∘W

minus30

Pilcomayo riverlineament

26∘S

23∘S

57 ∘W

57 ∘W

55∘W

25∘S

minus60

minus40

minus60

minus60

minus5010

100

10

20

0

minus40minus30

0

minus10minus20

minus40

100

10

20

30

10

Landsat imageryAeromagneticlineamentsBouguer gravity-interval 10 mgal-

010

BV

PJC

MB

SE

A

Asuncion

NL

S

R

VParaguay Seismicity

Depth of theearthquakes h lt70 km

Figure 3 Geological sketch map showing aeromagnetic and Landsat lineaments in Eastern Paraguay and Bouguer gravity data [16ndash18]Gravity lows BV Bella Vista PJC Pedro Juan Caballero MB Mbacarayu SE San Estanislao (formerly San Pedro) A Asuncion S SapucaiV Villarrica (ASV graben) R Santa Rosa Inset distribution of earthquakes with depth lt70 km [29]

Vauchez [30] rift orientations seem to have been controlledby the preexisting lithospheric mantle fabric as indicated bydeep geophysical data

The thermal history using apatite fission track analyses(AFTA) reveals that at least two main episodes have beenidentified in sedimentary and igneousmetamorphic samplesranging in age from Late Ordovician to Early Cretaceous[31 32] AFTA data from ASV show evidence for rapidcooling beginning sometime between 90 and 80Ma similarto the results found along Brazilian and Uruguayan coasts ATertiary heatingcooling episode is also suggested by AFTAdata (60ndash10Ma) supporting early work in the area The timeof the first event is significantly younger than any riftingactivity related to the Parana flood basalts and to the openingof the South Atlantic Late Cretaceous cooling may haveinvolved several kilometers of differential uplift and erosionand would have played an important role in the controlof the geomorphology and drainage patterns of the regionespecially in the ASV system [31 32]

Beginning from Mesozoic times (Figure 2) almost fivemain alkaline magmatic events have occurred in EasternParaguay other than the Early Cretaceous tholeiitic mag-matism (133-134Ma [4]) Three of these include rocks ofsodic affinity corresponding geographically to the provincesof Alto Paraguay (2415 plusmn 13Ma) Misiones (1183 plusmn 16Ma)and Asuncion (587 plusmn 24Ma) whereas two involve rocksof potassic affinity associated with the Apa and Amambayprovinces both of similar age (1389 plusmn 07) and with theCentral Province (ASV 1264 plusmn 04Ma)

3 Asuncioacuten-Sapucai-Villarrica Graben (ASV)

The ASV graben (Figure 4) is the dominant rifting structurein Eastern Paraguay linked to NE-SW extensional vectors[13] and it is characterized by a gravity anomaly trendingN30-45W near Asuncion townships (Figure 3) The grabennearly symmetrical and defined by major faults along eachmargin [1 12 18 37] may be subdivided into three main


18

Early Cretaceous tholeiiticbasalts (Alto Parana formation)Triassic-Jurassiccontinental sedimentsCarboniferous and Permiancontinental sedimentsLate Ordovician-EarlySilurian continental sedimentsCambrian-Ordoviciancrystalline basement

Tertiary Na-alkalinecomplexes and dykesEarly CretaceousK-alkaline complexesand dykes

Major faults

N

0 10 20

(km)

Chaco

River

E

C

F

GH

B

DA

Asuncion

Ypacaraı valley

Yaguaron

Paraguarı

Carapegua

Acahay

22

21

20

I

JK

L

La Colmena

14

1210

11

13

M8

9

2

31

4

56

7

Villarrica

Sapucai

Caballero

Ybytyruzuhills

Asuncion-Sapucai-Villarrica graben

Tertiary-quaternarysediments

17

Ybycuı

15

19

Figure 4 Geological sketchmap of the Asuncion-Sapucai-Villarrica graben showing themain occurrences ofmagmatic rock-types modifiedafter [33] In parentheses preferredKAr and plateauArAr ages (in bold) inMa according to [4 33]K-alkaline complexes 1 CerroKm23 (132128) 2 Cerro San Benito (127) 3 Cerro E Santa Elena (126) 4 Northwestern Ybytyruzu (125ndash129) 5 Cerro Capiitindy (na) 6 Mbocayaty(126ndash130 126) 7 Aguapety Porton (128ndash133 126) 8 Cerro Itape (na) 9 Cerrito Itape (na) 10 Cerro Canada (127) 11 Cerro Chobı (na)12 Potrero Garay (na) 13 Catalan (na) 14 Cerro San Jose (127) 15 Potrero Ybate (126ndash128 128) 16 Sapucai (119ndash131 126) 17 Cerro SantoTomas (126ndash130 127) 18 Cerro Porteno (na) 19 Cerro Acahay (118 127) 20 Cerro Pinto (na) 21 Cerro Ybypyte (124) 22 Cerro Arrua-ı(126ndash132 129) Na-alkaline complexes A Cerro Patino (39) B Limpio (50) C Cerro Verde (57 61) D Nemby (46 61) E Cerro Confuso(55ndash61) F Nueva Teblada (46ndash57) G Lambare (49) H Tacumbu (41ndash46 58) I Cerro Yariguaa (na) J Cerrito (56) K Cerro Gimenez (66)L Cerro Medina (na) M Colonia Vega (na) Detailed information on the single occurrences that is geological map location countryrocks forms and main rock-types is provided in [33ndash36] na not available

segments (Figure 4) (1) the northwestern part between theAsuncion and Paraguarı townships indicated also by theintragraben Ypacaray rifting and by the presence of Na-alkaline mafic-ultramafic plugs carrying mantle xenoliths(Asuncion Province age between 66 and 39Ma cf Figure 4)(2) a central area defined between Paraguarı and LaColmenatownships characterized by K-alkaline complexes and dykes(average age 127Ma cf Figures 3 and 4) and by subordinateNa-alkaline complexes and dykes (age around 66ndash60Ma) (3)the eastern part between La Colmena and the Ybytyruzuhills characterized by K-alkaline complexes and dykes (agearound 130ndash125Ma) and by tholeiitic lavas and flows (agearound 133ndash130 Ma cf [4])

Geology and gravity results indicate that the ASV grabenextends up to 100 km into the Chaco Basin (Figures 2 and 3)and turns to anN80Wtrend betweenParaguarı andVillarricatownships in the area marked by a gravity low anomalythat increases eastwards (Figures 3 and 4) Paleomagnetic

data [38] revealed that the potassic Cretaceous rocks (75samples) have reversal polarity remnants corresponding toa paleomagnetic pole at 623∘E and 854∘S similar to thatcalculated for the Serra Geral Formation in the ParanaBasin It is therefore inferred that ASV K-alkaline rocks wereemplaced while the tholeiitic magmatic activity was stilltaking place (Figure 1)

Tertiary sodic rocks carrying mantle xenoliths mainlyoccur in an area characterized by relatively gravity highs(Figure 3) whereas the potassic complexes and dykes occurin a gravity low belt characterized by block faulting (Figures3 and 4) Finally an NS-trending fault system bounds thewestern side of the Ybytyruzu hills close to several alkalineintrusions [24] East of Villarrica

A total of 527 samples from the ASV area including220 dykes have been investigated in detail including fieldrelationships age orientation (dykes) petrography andmin-eral chemistry of the rocks reported in [10 13 33ndash36]


(I)(II)

(III)

K2O

K2O

15

10

5

0

15

10

5

0

0 5 10Na2O

Na2O

Sodic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

0 5 10

Sodic

32

1

4

5

67

89

1011

R2

R2

2000

1000

Intrusiverocks

R1

R1

R1

R1

SuiteNa K

VolcanicrocksSuite

Suite

Na K

Na K

1000

2000

1000

2000

R2Dykes

200010000minus1000minus2000

Foid-bearingsyenite

Foid-bearing monzodioriteFoid-bearing monzogabbro

Foid-bearingmonzonite

Foid syenite

Foid

monzosyenite

Foid

mon

zodi

orite

Foid

mon

zoga

bbro

AB-T

B-P

A P

F

B-P

AB-T

Foid dioriteFoid gabbro

Tholeiite L-TiTholeiite H-TiK-alkaline AB-T

K-alkaline BP

K-alkaline BPcarbonatites

Na-alkaline

3000

1000

Ankaratrite

Basanite

Alkali

basalt

NepheliniteTephritePhonotephrite

Trachyandesite

Trachybasalt

PhonoliteTrachyphonolite Trachyte

Olivine tholeiitebasalt

Andesite-basalt

R2

SGN

N

200010000minus1000minus2000

Foidolite

Figure 5 Compositional variation of the rock-types from ASV in terms of 1198771= 4Si minus 11(Na + K) minus 2(Fe + Ti) and 119877

2= 6Ca + Mg + Al

[39] (also Figure 2 of [13]) Data source [34] SG field of Serra Geral tholeiites ASV field of Na-alkaline rocks B-P and AB-T lineages of theK-alkaline rocks (basanite to phonolitic suite and alkaline basalt to trachyphonolitetrachyte suite resp white squares represent a lava flowand a theralite with carbonatitic affinity resp (see text)) Insets (I) the same with subdivision into intrusive and volcanic rocks and dykesplus Le Maitre [40] classification as in Figure 2 of [10] (II) QAPF diagram [41] for intrusive potassic suites from ASV as from Figure 3 of[10] (III) Azimutal frequence of the B-P and AB-T dykes [42] The symbols represent selected compositions as in Tables 1 to 4

55 of the dykes are preferentially oriented N20-60W(Figure 5 (III))

4 Classification Petrography andPetrochemistry of the Magmatic Rocks

The fine-grained texture of the ASV rocks including theintrusive variants is plotted on the De La Roche chemicalclassification [39] diagram (Figure 5) with an additionalsubdivision based on wt K

2O and Na

2O on LeMaitrersquos [40]

diagram (inset (I))4of the dykes have tholeiitic affinity sills lava flows and

dykes both high- and low-Ti variants according to [2 43]and straddle the fields of the olivine tholeiitic basalts and

andesite-basalts whereas 17 are sodic and 79 potassic incomposition The distribution of the potassic rocks showsthat the variation of the dykes is consistent with that of theassociated intrusive and volcanic rocks (inset (I)) Two mainlineages are apparent for the potassic rock-types (Figure 5and inset (II)) (1) a silica undersatured lineage (B-P) rangingfrom basanite to phonolite and peralkaline phonolite and (2)a silica-saturated lineage (AB-T) ranging from alkali basalt totrachyphonolite and trachyte [13 42 44]

In summary tholeiitic rock-types (both high-titaniumH-Ti and low-titanium L-Ti variants) K-alkaline and Na-alkaline rocks are widespread in a relatively narrow arearepresented by ASV graben (ca 35 times 200 km cf Figure 3)In Tables 1 to 4 representative and average analyses of theserocks are reported


41 Tholeiites The tholeiitic rocks are mainly lava flows(Ybytyruzu hills) and gabbro sills usually occurring near theYbycuı township (Figure 4) The textures are porphyritic toaphanitic (lava flows and dykes) and equi- to subequigranular(sills) characterized by the presence of two clinopyroxenes(augite and pigeonite) and by pronounced variations of TiO

2

(14 to 32 wt cf Table 1) and incompatible elements (IEeg Ba ca 150 to 400 ppm Zr ca 100 to 200 ppm) Thesevariations are similar to those common to tholeiitic basaltsof the Parana Basin that are dominated by low and highcontents of TiO

2(L-Ti and H-Ti variants southern and

northern Parana Basin with TiO2lt2 and gt25 wt resp cf

Figure 1) and IE [2 45 46] The mineral assemblages (augitepigeonite olivine plagioclase magnetite and ilmenite) showcrystallization temperatures around 1200ndash1000∘C and fO

2

conditions between NNO and QMF buffers [3]Mass balance calculations and the remarkable differences

in the ratios of the IE between L-Ti andH-Ti tholeiites suggestthat such differences cannot be explained by fractionalcrystallization or by means of melting and zone refiningprocesses of a homogeneous mantle source A basalt genesisfrom chemically different lithospheric mantle materials istherefore indicated Mixing processes seem to have played aminor role [2 47]

42 Potassic Suites The different lithotypes of the potassicrocks (cf Figure 5 and Tables 2 and 3) maybe subdivided intoB-P and AB-T lineages a distinction consistent with crystalfractionation models [13]

421 B-P Suite Theeffusive rock-types and dykes (basanitestephrites and phonotephrites) typically show porphyritictextures with phenocrysts of clinopyroxene (Wo40ndash50Fs10ndash19)olivine (Fo60ndash85) and leucite pseudomorphed by sanidine +nepheline in a glassy groundmass showing microlitesof clinopyroxene plusmn olivine Ti-magnetite plusmn ilmenite Ti-phlogopite-biotite alkali feldspar (Or15ndash88) and nepheline-analcime (Ne44ndash59Ks17ndash26) Phenocrystal plagioclase (upto An

74) is also present Accessory phases are amphibole

(pargasite-kaersutite) and apatite plusmn zircon Phonolites arecharacterized by phenocrysts of leucite-pseudomorphsalkali feldspar (Or47ndash75) clinopyroxene (Wo48ndash50Fs11ndash34)Fe-pargasite and nepheline plusmn biotite plusmn titanite plusmn melanite(Ti-andradite up to 68wt) plusmnmagnetite or haematite Glassygroundmass contains microlites of alkali feldspar nephelineand clinopyroxene plusmn Ti-andradite plusmn magnetite Haematiteis found replacing magnetite or as a common groundmassconstituent in peralkaline phonolites

The intrusive analogues (theralites essexitic gabbrosijolites and essexites) show a holocrystalline inequigranulartexture with diopsidic pyroxene (Wo44ndash51Fs8ndash17) olivine(Fo75ndash82 to Fo44ndash66) mica (Ti-phlogopite to Ti-biotite) Ti-magnetite alkali feldspar and nepheline (Ne64ndash80Ks20ndash36)plusmn leucite plusmn amphibole ldquoIntrusiverdquo leucite and leucite pseudo-morphed by analcime and plagioclase are common testifyingto subvolcanic conditions [24] Cumulitic textures are repre-sented by clinopyroxene with alkali feldspar + nepheline +carbonate as intercumulus phases

On the whole the temperatures calculated for themineral assemblages span from 1250 to 1200∘C and from1130 to 1080∘C pheno- and microphenocrysts respec-tively under about 1 kb H

2O pressure and around 1000∘C

under atmospheric pressure lower temperatures for exam-ple 900ndash700∘C suggest possible subsolidus exchange reac-tions (eg albitization) Magnetite-ilmenite pairs definetemperatures between 1000 and 1100∘C along the NNObuffer [12]

Notably the B-P suite is also characterized by carbonatiticmagmatism although it is very limited in volume A silicobe-forsitic flow is present in the Sapucai lava sequences and asldquoocellirdquo at the Canada and Cerro E Santa Helena K-alkalinecomplexes [48]These primary carbonates are relevant as theyreveal a CO

2imprinting after the tholeiitic magmatism

422 AB-T Suite Alkali gabbros syenogabbros and syen-odiorites are usually porphyritic and seriate in texture Theycontain clinopyroxene (Wo43ndash50Fs6ndash14) olivine (Fo43ndash82)Ti-biotite Ti-magnetite plusmn ilmenite plagioclase (An31ndash78)alkali feldspar (Or60ndash84) interstitial nepheline-analcime(Ne37ndash82Ks15ndash23) and alkali feldspar (Or80ndash97) Accessoriesare apatiteplusmn amphiboleplusmn titaniteplusmn zirconNepheline syenitesand syenites are texturally equi- to subequigranular andseriate The rock-types are characterized by alkali feldspar(Or32ndash63) clinopyroxene (Wo43ndash48Fs10ndash32) and nepheline(Ne85) and hastingsite Common accessories include titanite

and apatite plusmn carbonate plusmn zirconAlkali basalts trachybasalts and trachyandesites

are porphyritic rocks exhibiting phenocrysts andormicrophenocrysts of clinopyroxene (Wo44ndash49Fs7ndash15) olivine(Fo65ndash83) plagioclase (An28ndash76) magnetite and biotiteset in a glassy groundmasses consisting of microlites ofclinopyroxene (Wo46ndash49Fs13ndash18) magnetite ilmenite biotiteplagioclase (An20ndash45) alkali feldspar (Or52ndash65) nepheline-analcime (Ne37ndash73Ks22ndash38) amphibole and apatiteplusmn titanite plusmnzircon

Trachyphonolites and trachytes are porphyritic toaphyric The phenocrysts are alkali feldspar (Or60ndash65) plusmnclinopyroxene (Wo46ndash49Fs14ndash20) plusmn plagioclase (An14ndash16)pseudomorphosed leucite amphibole and biotite in ahypocrystalline to glassy groundmass containing microlitesof alkali feldspar biotite and clinopyroxene plusmn biotite plusmnamphibole plusmnmagnetite plusmn Ti-andradite plusmn haematite

Notably the equilibration temperatures of the mineralassemblages are very similar to those suggested for the B-Psuite [10 13 49]

The differentiation history of the potassic ASV mag-mas remained largely into the stability fields of the fer-romagnesian phases [12] that is olivine + clinopyrox-ene in the system Mg

2SiO4-KAlSiO

4[10 13 51] sug-

gesting that relatively high temperature subvolcanic con-ditions were prevalent Moreover the extreme differenti-ates from both B-P and AB-T suites approaches to thecomposition of peralkaline residua pointing to an exten-sive subvolcanic crystallization of K-rich aluminous phaseslikely phlogopite and leucite at least for the B-P suite[52]


Table 1 Averages of representative chemical analyses (recalculated to 100 wt on anhydrous basis in parentheses standard deviation) oftholeiites fromASV [33 34 44] L-Ti and H-Ti tholeiites according to [2 45]The 120576 time-integrated notations are calculated using the presentday Bulk Earth parameters [50] that is UR = 07047 (87Rb86Sr = 00816) and CHUR = 0512638 (147Sm144Nd = 01967 Mg molar ratioMgO(MgO + FeO))

Suite L-Ti L-Ti H-Ti H-Titholeiite basalt andesite-basalt basalt Andesite-basaltNo of samples (3) (3) (6) (5)Wt

SiO2 5020 (079) 5306 (040) 5083 (084) 5052 (060)TiO2 140 (006) 136 (011) 258 (036) 319 (060)Al2O3 1464 (021) 1378 (009) 1398 (045) 1425 (063)FeOtot 1273 (039) 1342 (049) 1354 (056) 1455 (113)MnO 019 (005) 025 (005) 021 (002) 021 (002)MgO 736 (022) 553 (008) 513 (044) 419 (065)CaO 1063 (066) 855 (005) 965 (062) 856 (044)Na2O 236 (011) 266 (020) 261 (015) 249 (029)K2O 033 (005) 107 (018) 110 (017) 114 (010)P2O5 015 (002) 019 (001) 037 (009) 036 (004)

Mg 066 055 054 048ppm

La 62 (08) 90 (10) 253 (63) 260 (60)Ce 160 (17) 210 (29) 604 (122) 500 (20)Nd 111 (13) 141 (22) 283 (36) 250 (30)Sm 34 (03) 43 (04) 77 (15) 68 (11)Eu 12 (01) 15 (01) 22 (02) 19 (02)Gd 43 (06) 54 (08) 77 (12) 69 (11)Dy 48 (05) 60 (09) 63 (15) 57 (13)Er 29 (04) 36 (06) 39 (13) 35 (09)Yb 26 (04) 32 (04) 34 (12) 32 (10)Lu 034 (007) 042 (009) 049 (015) 050 (019)Cr 325 (27) 62 (1) 119 (15) 48 (2)Ni 103 (18) 55 (7) 60 (15) 54 (12)Rb 13 (4) 13 (1) 24 (3) 33 (11)Sr 188 (42) 187 (2) 386 (90) 334 (15)Ba 154 (19) 190 (4) 409 (78) 347 (37)Th 11 (01) 17 (02) 20 (01) 30 (02)U 024 (005) 037 (008) 043 (008) 065 (004)Ta 028 (004) 042 (007) 12 (03) 18 (04)Nb 40 (10) 61 (10) 13 (2) 20 (1)Zr 83 (10) 113 (2) 190 (36) 197 (6)Y 28 (2) 42 (1) 33 (4) 36 (3)

Measured(87Sr86Sr) 070548 (20) 070535 (20) 070617 (21) 070620 (18)(143Nd144Nd) 051271 (9) 051272 (10) 051239 (2) 051240 (1)

Age (Ma) 1316

Initial ratio(87Sr86Sr)i 070502 070456 070576 070554(143Nd144Nd)i 051256 051256 051225 051226119879DM 1991 1976 2127 2037

1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410


43 The Sodic Rocks These consist mainly of ankaratrites +(mela)nephelinites (45) and phonolites (42) (Comin-Chiaramonti et al [10 13 44]) Representative chemicalanalyses are reported in Table 4

Phenocrysts-microphenocrysts in ankaratrites andnephelinites are characterized by olivine (phenocrysts 1ndash7 vol Fo

89ndash85 mole 1ndash6 vol microphenocrysts Fo82ndash77

mole) clinopyroxene (phenocrysts 1ndash6 vol Mg sim08)titanomagnetite (03ndash07 vol up to 38 ulv mole) andoccasionally phlogopite microphenocrysts The hypo-crystalline groundmass contains clinopyroxene (39ndash46 volMg sim075) olivine (3ndash6 vol Fo

74ndash76 mole) tita-nomagnetite (4ndash7 vol up to 43 ulv mole) nepheline(16ndash21 vol) and glass (11ndash25 vol) [53]

Phonolites are typically microphyric to hypocrystallinewith alkali feldspar phenocrysts or microphenocrysts(Or43ndash83) nepheline (Ne67ndash79) occasionally altered to can-crinite acmitic clinopyroxene (acmite up to 63wt) andferroedenite-ferropargasite amphibole Hauyne micahaematite and zircon are typical accessory mineralsAnalcime occurs as a nepheline pseudomorph Ti-andraditeand titanite phenomicrophenocrysts are present in somedykes [10]

Lherzolite harzburgite dunite mantle xenoliths andxenocrystic debris are common and abundant in the ankara-trites and nephelinites [54] from eastern ASV (Figure 3)

The generation of the ASV nephelinites may be modelledfor 4ndash6 degrees of partial melting with crystallization tem-peratures between 1200 and 1000∘C from garnet peridotitesources [10 55]

44 Mantle Xenoliths The xenoliths are mainly spinel-lherzolites harzburgites and subordinate dunites The dom-inant texture is protogranular rarely tabular or porphyro-clastic [54] The Paraguay mantle xenoliths contain variableamounts of glassy patches (blebs) and glassy drops in clinopy-roxenes [56] The latter show an overprinted spongy texture[54] The blebs (whole composition Mg 088ndash091) consistmainly of a glassy matrix having microlites of olivine (Mg091-092) clinopyroxene (Mg 091ndash093) Cr-spinel and(rarely) phlogopite (Mg 086ndash092) According to [56 57]they were formed by decompression melting of amphiboleand phlogopite

The Paraguayan xenoliths are characterized by a largerange of K

2O (002 to 051 wt) Some xenoliths have K

2O

abundances comparable or even higher than those reportedfor metasomatized mantle peridotites [58] resemblingin some cases to amphibole-mica-apatite-bearing mantle-xenolith suites [59] K

2Ocontents and the abundance of blebs

and glassy drops allow to group the Paraguay xenoliths intotwo main suites that is a low-K suite (LK K

2O lt015 wt)

and a high-K suite the latter with abundant glassy dropsandor variable amounts of blebs and spongy clinopyroxenes(HK K

2O ge02 wt) Representative analyses are listed in

Table 5 and complete sets of chemical analyses are in [54]Based on Sperarsquos [60] approach Comin-Chiaramonti

et al [55] suggested that the ascent of the xenoliths to thesurface took place in a very short time for example less thannine days (assuming a diameter of 45 cm corresponding to

the largest xenolith size a density of 33 gcm3 and an originof the hosting liquids from depth sim70ndash75 km ie simboundarybetween garnet and spinel peridotite)Thesemantle xenolithsprovide a direct sampling of the subcontinental mantle inASV along with the metasomatic processes [61 62]

Coherent variations of major element in both suitesfollow a dunite-lherzolite sequence trending to the mantlecomposition [54] The population is represented mainly bylherzolitic-harzburgitic (dunitic) compositionsmostlywith a055ndash063 range of (SiO

2+Al2O3)(MgO+FeOt)molar ratio

The residual character of the harzburgitic mantle xenoliths(believed to be consistentwithmelting and basalt-componentremoval) is also indicated by the decrease in the cpxopxmodal ratio with decreasing modal cpx which fits the modelvariation trend induced by partial melting of lherzolite [5663]

Equilibration temperatures for orthopyroxene-clino-pyroxene pairs [64] and for olivine-spinel pairs [65] varybetween 862∘ and 1075∘C and between 748∘ and 968∘Crespectively Intracrystalline temperatures [66ndash68] forclinopyroxene and orthopyroxene pairs vary between 936∘and 1033∘C and between 920 and 1120∘C (LK and HK suitesresp with pressures in the range of 11ndash23 GPa for bothsuites with the higher values related to the more depletedxenoliths from the LK suite [53 56])

The oxygen isotope compositions on separates of clinopy-roxene and coexisting olivine (12057518Opermil) vary from 55 to60permiland from 50 to 61permil respectively [53] These isotopicratios are in the range for worldwide mantle phases olivine44 to 75permil and clinopyroxene 48 to 67permil [69 70] andfor South America mantle xenoliths olivine 49 to 64permiland clinopyroxene 50 to 60permil [71] The calculated Cpx-Olisotopic temperatures [53 71] are around 970ndash1070∘C 1030ndash1130∘C (LK) and 1100ndash1180∘C (HK) suggesting equilibrationtemperatures higher in the HK suite than in LK suite

The highest temperature of the HK suite is substantiallydue to higher 12057518Opermil in olivine than 12057518Opermil in clinopy-roxene According to [72] the relatively low 12057518O in thepyroxenes reflects metasomatism by a silicate melt fromsubducted altered oceanic crust Therefore the ParaguayanHK suite would be for some geologists the best candidate fora subduction-related environment

Notably the ASV clinopyroxenes [73] have 119881Cell and119881M1 sites intermediate between those of plagioclase- andgarnet-bearing mantle peridotites that is in a pressure rangebetween 12 and 22GPa Thus isotopic and crystallographicresults are internally consistent

On the whole the ASV xenoliths define a geotherm [53]which starting at about 830∘C and 10GPa at the transitionmantle-crust intersects the hydrous peridotite solidus atabout 1140∘C and 21-22 GPa in the spinel peridotite faciesnear to the transition with the garnet peridotite faciesbelieved to be the source of the sodic alkaline magmatism

5 Geochemistry

Incompatible elements (ie large ion lithophile elementsIE LILE and high field strength elements (HFSE))


Table 2 Representative chemical analyses (recalculated to 100 wt on anhydrous basis in parentheses standard deviation) of K-alkalinerocks (B-P suite effusive and intrusive equivalents and dykes) from ASV [10 13 24] Analysis of a silicobeforsitic flow on anhydrous basis isalso shown [48 74] Ages as in [4]

Suite B-P

K-alkaline Basanite Tephrite Phonotephrite Phonolite Silicobeforsite22 dolomite

Silicobeforsitecarb fraction

No of samples (4) (6) (4) (1) (1)Wt

SiO2 4695 (214) 4908 (131) 5236 (164) 4869 4905 mdashTiO2 178 (019) 194 (026) 142 (019) 197 194 mdashAl2O3 1284 (163) 1294 (117) 1727 (124) 1642 1532 mdashFeOtot 1020 (180) 1002 (097) 739 (075) 845 960 mdashMnO 018 (003) 017 (002) 015 (002) 015 017 mdashMgO 995 (202) 788 (164) 366 (058) 386 528 mdashCaO 1131 (141) 936 (085) 700 (102) 696 881 mdashNa2O 242 (061) 299 (092) 434 (058) 379 350 mdashK2O 378 (118) 499 (124) 573 (017) 860 614 mdashP2O5 059 (021) 066 (018) 058 (007) 069 034 mdash

Mg 067 062 051 045 mdash mdashppm

La 821 (190) 912 (130) 933 (136) 98 80 23906Ce 1626 (304) 1641 (181) 1700 (250) 186 145 42034Nd 644 (109) 693 (49) 666 (121) 732 62 15989Sm 128 (24) 128 (36) 114 (16) 151 113 1906Eu 30 (06) 30 (04) 28 (03) 202 23 390Gd 74 (19) 68 (11) 71 (06) 593 88 1490Dy 44 (06) 36 (02) 39 (04) 286 62 1057Er 19 (04) 17 (03) 19 (03) 159 33 540Yb 16 (01) 14 (04) 15 (03) 159 19 316Lu 025 (001) 021 (006) 026 (006) 023 028 032Cr 275 (106) 378 (260) 36 (23) 53 51 mdashNi 81 (29) 111 (42) 28 (18) 22 18 mdashRb 88 (18) 117 (51) 111 (35) 260 148 021Sr 1134 (279) 1661 (227) 1569 (10) 1626 1126 268Ba 1179 (252) 1582 (147) 1462 (215) 1935 1350 mdashTh 144 (99) 114 (35) 121 (16) 127 152 mdashU 29 (10) 24 (07) 25 (01) 35 42 mdashTa 32 (02) 30 (07) 32 (03) 51 27 mdashNb 380 (70) 44 (10) 47 (1) 62 35 mdashZr 246 (42) 282 (91) 259 (35) 365 280 mdashY 140 (28) 173 (67) 189 (30) 13 18 2375

Measured(87Sr86Sr) 070761 (4) 070774 (3) 070727 (4) 070752 (2) 070807 (2) 070762 (3)(143Nd144Nd) 051182 (4) 051171 (1) 051160 (4) 051187 (2) 0511804 (6) 0511371 (8)

Age 130 129 124 125 128 mdash

Initial ratio(87Sr86Sr)i 070697 070716 070671 070645 070700 070717(143Nd144Nd)i 051172 051162 051152 051177 051171 051131119879DM 2049 2042 2043 2067 1884 1844

1198771

1054 713 365 minus397 mdash mdash1198772

1955 1646 1269 1258 mdash mdash120576Sr 3431 3704 3058 2688 347 3417120576Nd minus1469 minus1671 minus1878 minus1383 minus148 minus227


Table 3 Representative chemical analyses (recalculated to 100 wt on anhydrous basis in parentheses standard deviation) of K-alkalinerocks (AB-T suite effusive and intrusive equivalents and dykes) from ASV [13 74] Ages as in [4]

Suite AB-TK-alkaline Alkaline basalt Trachybasalt Trachyandesite Trachyphonolite TrachyteNo of samples (3) (3) (7) (5) (1)Wt

SiO2 4869 (150) 5090 (156) 5316 (118) 5825 (144) 5895TiO2 169 (048) 149 (031) 142 (021) 091 (023) 194Al2O3 1517 (186) 1707 (106) 1699 (145) 1839 (101) 1903FeOtot 1031 (076) 904 (057) 796 (075) 487 (151) 449MnO 019 (001) 016 (002) 015 (002) 016 (001) 012MgO 671 (089) 501 (024) 403 (058) 089 (090) 169CaO 1109 (063) 858 (111) 695 (066) 459 (109) 337Na2O 316 (042) 364 (044) 410 (038) 589 (138) 421K2O 246 (042) 365 (072) 461 (106) 576 (113) 700P2O5 055 (036) 050 (017) 055 (009) 029 (010) 025

Mg 058 053 051 032 040ppm

La 512 (160) 540 (186) 828 (297) 1540 (339) 136Ce 1067 (244) 1090 (210) 1542 (557) 2611 (442) 206Nd 527 (197) 479 (129) 647 (157) 840 (177) 78Sm 105 (16) 94 (305) 108 (21) 127 (35) 151Eu 28 (10) 25 (03) 28 (05) 328 (08) 39Gd 68 (24) 60 (12) 64 (10) 570 (16) 94Dy 41 (07) 42 (06) 42 (07) 544 (11) 63Er 17 (01) 18 (03) 16 (04) 259 (058) 23Yb 15 (01) 16 (04) 16 (04) 225 (046) 20Lu 022 (005) 024 (003) 028 (008) 035 (008) 031Cr 143 (24) 92 (59) 38 (34) 10 (6) 8Ni 49 (6) 31 (18) 17 (12) 6 (2) 2Rb 53 (13) 98 (16) 87 (20) 7 (3) 133Sr 1573 (263) 1389 (407) 1474 (194) 77 (34) 600Ba 1033 (321) 1280 (170) 1211 (168) 1377 (215) 1726Th 43 (21) 79 (15) 146 (85) 317 (85) mdashU 13 (05) 17 (06) 34 (30) 95 (33) mdashTa 23 (11) 16 (04) 28 (07) 26 (06) 25Nb 181 (90) 250 (60) 40 (12) 62 (18) 61Zr 260 (31) 220 (33) 268 (14) 411 (128) 392Y 145 (92) 146 (65) 195 (32) 25 (4) 23

Measured(87Sr86Sr) 070717 (4) 070721 (5) 070753 (4) 070752 (2) 070807 (2)(143Nd144Nd) 051185 (4) 051170 (3) 051160 (4) 051187 (2) 051181 (6)

Age 125 119 129 125 128

Initial ratio(87Sr86Sr)i 070693 070673 070709 070708 070639(143Nd144Nd)i 051175 051161 051151 051179 051171119879DM 2009 2199 1999 1530 2001

1198771

1215 954 749 545 6491198772

1817 1501 1277 1014 818120576Sr 3368 3074 3609 3585 260120576Nd minus1416 minus1712 minus1868 minus1331 minus149


Table 4 Representative chemical analyses (recalculated to 100 wt on anhydrous basis in parentheses standard deviation) of Na-alkalinerocks from ASV ASV [13 74] Ages as in [4]

Suite sodicNa-Alkaline Ankaratrite Ankaratrite Ankaratrite Melanephelinite Peralkaline PhonoliteNo of samples (1) (1) (5) (1) (1)Wt

SiO2 4371 4397 4329 (065) 4567 5596TiO2 239 212 250 (048) 221 043Al2O3 1484 1387 1342 (095) 1483 2119FeOtot 1001 1044 1071 (040) 783 404MnO 018 021 019 (001) 020 022MgO 1007 987 1147 (123) 892 021CaO 1206 1081 1182 (028) 1078 134Na2O 515 600 412 (021) 673 1077K2O 089 151 161 (032) 154 576P2O5 090 122 088 (014) 128 008

Mg 074 072 069 058 022ppm

La 81 119 842 (124) 118 120Ce 145 186 1628 (243) 190 191Nd 434 637 552 (85) 651 65Sm 815 1123 94 (12) 1145 11Eu 189 215 27 (03) 218 mdashGd 577 516 67 (07) 523 mdashDy 481 481 55 (07) 500 mdashEr 213 275 24 (03) 286 mdashYb 165 179 18 (03) 187 mdashLu 023 027 027 (004) 028 mdashCr 542 648 490 (74) 470 2Ni 207 273 249 (48) 239 6Rb 22 59 53 (13) 63 60Sr 1016 1013 1109 (63) 1095 654Ba 1090 980 1090 (95) 1094 367Th 105 105 110 (24) 116 mdashU 23 23 24 (05) 25 mdashTa 59 59 84 (10) 65 mdashNb 86 101 105 (13) 113 mdashZr 152 234 250 (43) 228 955Y 26 33 29 (4) 32 39


Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772

2080 1918 2096 1886 570120576Sr minus1042 minus1430 minus1305 minus1179 minus1119

120576Nd 267 291 223 257 154


Table 5 Average chemical analyses (recalculated to 100 wt on anhydrous basis in parentheses standard deviation) of mantle xenoliths (LKandHK suites K2O lt015 wt and gt02 wt respfromASV [53 54 56]The age is the average of ages of Table 4The bleb is a representativeglassy drop in an H-K harzburgite [54 56]

Whol-rock L-K L-K H-K H-K H-Klherzolite harzburgite lherzolite harzburgite bleb

No of samples (5) (6) (3) (2) (1)Wt


ppmLa 169 (012) 287 (051) 266 (052) 671 (069) 7739Ce 153 (009) 409 (075) 335 (067) 845 (081) 10625Nd 020 (001) 028 (016) 096 (055) 242 (025) 2774Sm 0012 (0004) 0038 (0015) 0260 (0014) 051 (020) 416Eu 0001 (0001) 0006 (0002) 0010 (001) 0020 (0006) 100Gd 007 (0008) 004 (001) 037 (002) 074 (003) 292Dy 010 (001) 005 (001) 043 (002) 091 (004) 261Er 007 (0001) 005 (001) 030 (001) 065 (006) 168Yb 007 (0001) 008 (001) 029 (001) 063 (003) 123Lu mdash mdash mdash mdashCr 2601 (350) 2421 (357) 2360 (88) 2635 (30) 38114Ni 2307 (160) 2309 (102) 2120 (4) 2307 (73) 1124Rb 333 (951) 267 (163) 750 (212) 600 (141) 120Sr 2241 (1047) 1115 (458) 2889 (1029) 6467 (762) 1414Ba 200 (100) 467 (118) 40 (8) 345 (148) 1781Th mdash mdash mdash mdash mdashU mdash mdash mdash mdash mdashTa mdash mdash mdash mdashNb 591 (058) 178 (020) 639 (177) 698 (101) 155Zr 595 (041) 608 (045) 690 (013) 786 (093) 189Y 051 (010) 072 (009) 262 (009) 570 (108) 1470

Measured(87Sr86Sr) 070426 (000005) 070421 (000038) 070416 (000006) 070395 (000002) mdash(143Nd144Nd) 051264 (000007) 051275 (000039) 051299 (000033) 051288 (000005) mdash

Age (50 plusmn 6) (50 plusmn 6) (50 plusmn 6) (50 plusmn 6) mdash

Initial ratio(87Sr86Sr)i 070398 070376 070367 070377 mdash(143Nd144Nd)i 051263 051272 051294 051285 mdash119879DM 427 448 446 453 mdash

120576Sr minus940 minus1255 minus1380 minus1231 mdash120576Nd 106 292 708 516 mdash


considered with the Sr-Nd isotopic composition indicatethat the ASV magmatic was generated from geochemicallydistinct (enriched versus depleted) mantle sources (cf [75])

51 Incompatible Elements Mantle-normalized IE patternsfor the various and different magmatic rock groups arerepresented in Figure 6

The L-Ti and H-Ti ASV tholeiites are distinct in termsof their relatively low elemental abundances and highLILEHFSE ratios In particular theirmarked Ta-Nb negativespikes are similar to those of the potassic alkaline magmasfromASV but clearly different in comparison to theCenozoicsodic alkaline rocks from the same area

The suites are similarly enriched in REE and exhibitsteep subparallel LREE trends ((LaLu)CN = 26ndash161 17ndash62and 11ndash46 for B-P AB-T and Na rocks resp) which tend toflatten out for HREE ((DyLu)CN = 124ndash196 109ndash200 and056ndash205 for B-P AB-T and Na rocks resp) HK-dykes areexcepted REE profiles with LREE enrichment and flat HREEsuggestmantle sources previously depleted bymelt extractionand subsequently enriched [76]

Multielemental diagrams normalized to a primordialmantle composition (Figure 6) show a substantial overlap ofB-P and AB-T compositions negative Nb Ta P Ti and Yspikes and positive U K and Sr anomalies In general B-P compositions are higher in Rb K Zr Hf Ti Y LREEand MREE than AB-T compositions On the contrary theNa rocks yielded LaNb and LaTa ratios close to unityrespectively and NbK and TaK ratios greater than 10respectively Notably the variations of incompatible elementsof the AB-T compositions mimic to some extent those ofthe ASV H-Ti (and L-Ti) tholeiitic basalts which approachthe lower (Rb to Nd) and higher (Sm to Lu) elementalconcentrations of that suite (Figure 6)

In summary substantial overlap in bulk-rock chemistryexists between the investigated B-P and AB-T rocks bothcharacterized by variable KNa ratio the K types being dom-inant REE and other incompatible elements show similarconcentration levels and variation trends in the two suitesThe mantle normalized incompatible element patterns ofboth ASV suites show strong affinities including negativeldquoTa-Nb-Ti anomaliesrdquo with the Parana tholeiites [10]

On the whole the geochemical features suggest that theenrichment processes were related to small-volume melts ina lithospheric mantle [4 10 74]

52 Sr-Nd Isotopes The investigated rocks from ASV show alarge distribution of Sr-Nd isotopic compositions (Figure 7)delineating a trend similar to the ldquolow Ndrdquo array of [77](cf also ldquoParaguay arrayrdquo of [4]) Due to the high Sr andNd of the most ldquoprimitiverdquo alkaline rocks and associatedcarbonatites from Eastern Paraguay Comin-Chiaramonti etal [12] suggested that initial Sr-Nd isotopic ratios of theserocks can be considered uncontaminated by the crust and asa result representative of the isotopic composition of theirmantle source(s) The ASV potassic rocks have the highest(time integrated) Sri and the lowest Ndi Including the car-bonatites of the BP-suite [24 78] the Sri and Ndi range from

070645 to 070716 and from 051151 to 051179 respectively(Tables 2 and 3) These values are quite distinct from thoseof the ASV Paleocene sodic rocks (ca 60Ma) which plotwithin the depleted quadrant (Sri = 070364ndash070391 Ndi= 051264ndash051273 cf Table 4) towards the HIMU-DMMdepleted mantle components (Figure 7) Notably Sri and Ndiof the tholeiites believed to be uncontaminated [10] bothH- and L-Ti are intermediate between the potassic and sodicrocks 070456ndash070576 and 051225ndash051256 respectively (cfTable 4) These values approach to the range of the EarlyCretaceous uncontaminated tholeiites from the Parana Basin[47] that is Sri = 070527 plusmn 000051 and Ndi = 051264 plusmn000011 To be stressed that the genesis of these tholeiitesrequires lithospheric mantle components as indicated by K-alkaline and carbonatitic rocks from ASV [4 5]

Considering the whole Parana-Agola-Etendeka system(PAE) and that the ASV is located at the central westernmostside of the PAE [5 6] the different geochemical behaviourin the different PAE sectors implies also different sourcesUtilizing the 119879DM (Nd) model ages [78 79] it should benoted that (1) the H-Ti flood tholeiites and dyke swarmsfrom the Parana Basin and the Early Cretaceous potassicrocks and carbonatites from Eastern Paraguay range mainlyfrom 09 to 21 Ga whereas in Angola and Namibia the EarlyCretaceous K-alkaline rocks vary from 04 to 09Ga (2) theL-Ti tholeiites display a major 119879DM variation from 07 to24Ga (mean 16 plusmn 03) with an increase of the model agesfromNorth to South (3) Late Cretaceous alkaline rocks showmodel ages ranging from 06 to 1 Ga similar to the age spanshown by the Triassic to Paleocene sodic alkaline rock-typeslying along the Paraguay river [4]

Thusmodel ages suggest that some distinct ldquometasomaticeventsrdquo may have occurred during Paleoproterozoic to Neo-proterozoic times as precursor to the alkaline and tholeiiticmagmas in the PAE [78]

The significance of model ages is supported by (1) theisotopic overlapping of different igneous rocks (eg H-Tiand L-Ti tholeiites or K-alkaline rocks and carbonatites)which cannot be accidental and points to sampling of ancientreservoirs formed at different times from the same subconti-nental upper mantle [79] (2) whatever the implication thatis heterogeneity induced by recycled crust in the mantle[80 81] or occurrence of variably veined material in thesubcontinental uppermantle or both [82 83] Pb isotope dataindicate a mantle source of ca 18 Ga for the Parana H-Titholeiites Since much of the crust in southern Brazil appearsto have been formed at ca 2 Ga ago [84] it follows thatmagma genesis involved ancient lithospheric mantle reset atwell-defined isotopic ranges A veined lithospheric mantle(amphibolephlogopite-carbonate-lherzolite and amphibole-lherzolite + CO

2-fluid type III and IV veins ofMeen et al [85]

of Proterozoic age)maywell account for themagmatism bothof the PAE and ASV (Figure 8)

53 Mantle Sources The origin of the ASV magmas isclosely related to and probably constrained by the geo-dynamic processes which promoted the generation of theadjacent and coeval magmatism in Brazil [10]The origin and


1000

100

10

1

01

Tholeiitic magmatism from ASV

H-TiL-Ti

Rb Ba Th U K Nb Ta La Ce Sr Nd P SmZr Eu Ti Tb Y Yb Lu

1000

100

10

1

01

Rb Ba Th U K NbTa La Ce Sr Nd P SmZr Eu Ti Tb Y Yb Lu

ASV sodic magmatism

Ankaratritenephelinite

1000

100

10

1

01


ASV potassic magmatism B-P suite

Basanite-phonotephrite

Phonolite

Beforsite

1000

100

10

1

01

Rb Ba Th U K Nb Ta La Ce Sr Nd P Sm Zr Eu Ti Tb Y Yb Lu001

ASV mantle xenolithsBlebs

Na-ASV

LK HK

1000

100

10

1

01

Rb Ba Th U K NbTa La Ce Sr Nd P Sm Zr Eu Ti Tb Y YbLu

ASV potassic magmatism AB-T suite

Alkali basalt-trachyandesite

Trachyphonolite

Trachyte

1000

10

1

Rb Ba Th U K Nb Ta La Ce Sr Nd P Sm Zr Eu Ti Tb Y Yb Lu

Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt

Figure 6 ASV representative compositions (data source as in Tables 1 to 5) incompatible elements normalized to the primitive mantle [86]Parent magmas normalizations relative to the calculated parental magmas as proposed by [2 10 43 46] L-Ti (Mg 064 Ni 250 ppm) H-Ti(Mg 060 Ni 250 ppm) basanite (Mg 074 Ni 710 ppm) alkaline basalt (Mg 074 Ni 323 ppm) ankaratrite (Mg 070 Ni 993 ppm)


Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites

EM-I H-Ti tholeiites

EM-II

Paraguay array120576tSr

PS

TS

ASVpotassic rocks

Na-alkalineK-alkalineB-P suiteCarbonatitesB-P suite

K-alkalineAB-T suiteL-Ti tholeiites

H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22

minus25 minus15 minus5 5 15 25 35 45 55 65 75 85 95

Crystalline basementfrom eastern Paraguay

Figure 7 Sr and Nd isotopic plot in 120576-120576 notation 120576tSr versus 120576tNd correlation diagram for igneous rocks from ASV Data source Tables 1 to 5and [4 56 78 87ndash89] DM HIMU EMI and EMII mantle components terrigenous and pelagic sediments and TS and PS respectively [77]crystalline basement as in [10]The 120576tSr and 120576tNd time-integrated values were calculated using the following values for Bulk Earth 87Sr86Sr =07047 87Rb86Rb = 00827 143Nd144Nd = 0512638 147Sm144Nd = 01967 [50] Paraguay array is according to [4 5]

emplacement of the ASV magmatism occurred before dur-ing and after the opening of the SouthAtlantic and appears tobe related to early stages of lithospheric extension associatedwith an anomalously hot mantle [3 90 91] The KNa andtrace element variations and Sr-Nd isotope characteristics ofthe ASV suites support the view that the lithospheric mantleplayed an important role in their genesis as well as that of theParana flood basalts in Brazil [47 92 93]

It should be noted that the most mafic tholeiitic andpotassic ASV rock-types are relatively evolved comparedwithexpected primary compositions (eg Mg gt060ndash065 Nigt235 ppm) ankaratrite is excepted Possible ASV primarymelts (eg Mg sim074) in equilibrium with Fo

90-91 areexpected to have fractionated olivine (Ol) and clinopyroxene(Cpx) at or near the mantle source and certainly duringthe ascent to the surface [13] Neglecting the effects ofpolythermal-polybaric fractionation on the chemistry of thefractionates crystal fractions have been calculated to restorethe selected ASV parental compositions to possible near-primary melts in equilibrium with their mantle sources (cfTable 3 of [10])

Mass balance calculations starting from different garnet-phlogopite peridotites (cf [94] whole-rock and mineralcompositions in Table 3 of [10] and Table 10 of [43]) indicatethat the ASV composition of primary melts can be derivedfrom high and relatively high melting degrees of anhydrousgarnet or phlogopite-bearing peridotite that is 12 and 30for tholeiitic basalts (H-Ti and L-Ti respectively) and 4ndash11 for the alkaline rock-types (Table 3 of [10]) Howeverthe presence of a relative K enrichment in the ASV potassic

and tholeiitic rocks (Figure 6) suggests that aK-bearing phase(eg phlogopite) did not represent a residual phase duringpartial melting Phlogopite instead was probably a residualphase in themantle source(s) of theASV sodic rocksNotablythe parent melts (Figure 6) show high abundances of IEand high LREEHREE ratios which require mantle sourcesenriched in IE before or subcontemporaneously with meltingprocess [94] Nd model ages approximately indicate that theIE enrichment in the source mantle of the ASV tholeiitic andpotassic rocks probably occurred during Paleoproterozoictimes (mean 203 plusmn 008Ga) whereas those relative to thesodic rocks would be related to Late Neoproterozoic events(057 plusmn 003Ga) On the other hand the mantle xenolithsdisplay Nd model ages of 444 plusmn 11Ma (cf Tables 1 to 5)

Concluding the patterns of the mantle sources of theASV potassic rocks (along with H-Ti and L-Ti tholeiites) arecharacterized by negative ldquoTa-Nb-Tirdquo and positive Ba and Smspikes On the contrary the patterns of the mantle sourcesof the ASV sodic rocks (ankaratrites-melanephelinites) showpositive Ta-Nb andZr andnegativeK and Sm spikes It seemstherefore that the genesis of the ASV alkaline magmatism isdominated by a lithospheric mantle characterized by small-scale heterogeneity and documented by the occurrence ofbleb-like glass in spinel peridotite nodules from the sodicultramafic rocks [54 55]

Finally the isotopic signature of the tholeiitic and K-Na-alkaline-magmatism from the PAE in general and from ASVin particular may reflect ancient heterogeneities preservedin the subcontinental lithospheric mantle As matter of factall the geochemical data indicate that the PAE magmatism


DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II

Types III IVTo matrix

Na

Tholeiites

K

Carbonatites

87Sr86Sr

Figure 8 Calculated subcontinental upper mantle (SCUM)isotopic composition at 20Ga ago projected to 130Ma [85]modified after Figure 10 of [6] Parental melts with various RbSrand SmNd ratios are assumed for K Na (potassic and sodic rocksfrom ASV [10]) and PAE tholeiites [3] It should be noted that thecompositions of metasomites formed from a single metasomatizingmelt vary with the evolution of the melt Consequently the veinswill define a trend of shallow slope and mixing curves betweenvein and matrix will define an array towards the matrix (cf 120572and 120573 regression lines) Model depleted mantle (DMM) Rb = 0Sr = 0133 Sm = 0314 and Nd = 0628 present day Bulk Earth87Sr86Sr = 070475 87Rb86Sr = 00816 143Nd144Nd = 0512638and 147Sm143Nd = 01967 (RbSr)diopside (RbSr)melt asymp 0125(SmNd)diopside (SmNd)melt asymp 15 K RbSr = 00957 SmNd =01344 Na RbSr = 00732 SmNd = 02295 Th RbSr = 00733SmNd = 02082

Amazon Cratonminus16

minus18

minus20

minus22

minus24

minus26

minus28

minus64 minus62 minus60 minus58 minus56 minus54 minus52 minus50

PGA

Rio de la PlataCraton

ASV

PAR

PYL

Figure 9 Earthquakes distribution at the Paraguay and neighbour-ing regions open and full circles earthquake hypocenters gt500 andlt70 km respectively [29] Heavy black lines indicate extensionallineaments PGA Ponta Grossa Arch PAR and PYL Paraguays andPylcomaio lineaments respectively (cf also inset of Figure 3) Thedark grey delineates the rotational subplate trends [24 95] ASVAsuncion-Sapucai-Villarrica graben

Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()

minus15 minus09 minus06minus03 00 03 06 09 15

Longitude W (deg)

(b)

Figure 10 (a) General map including ASV showing contours (redlines) of the depth (km) of the subducting Nazca slab based onseismic data of [96] Heavy lines (black) outline the Cretaceousrift systems The hatched area roughly marks the extension ofintense early Paleozoic reworking of Proterozoic material but theexact border to the Brazilian Craton remains unknown [97] Pinkfields delineate inferred positions ofmajor cratonic fragments belowPhanerozoic cover [98] AAB Arequipa-Antofalla AC AmazonCraton AB Apa Block PR Paranapanema LP Rio de la PlataPA Pampia (b) Seismic tomography image [99] across a profileapproximately at 24∘ Lat S Note that the low-velocity feature inthe mantle to the East has been interpreted as a fossil mantle plume[100]

requires heterogeneous mantle sources also in terms ofradiogenic isotopes [6 10] such heterogeneities probably rep-resent metasomatic processes which have occurred mainly at05ndash10Ga and at 15ndash20Ga (cf 119879DM of Tables 1ndash4)

6 Geodynamic Implications

Some general considerations on the geodynamics are dis-cussed in [4ndash6 87ndash89] The ASV geodynamic evolution is


related to that of the Western Gondwana (Figure 1) whichreflects the regional amalgamation processes and requiresan overall understanding of the pre-Gondwanic setting atleast at the time of the Brasiliano cycle both at the Atlanticand Pacific systems The Brasiliano cycle was developeddiachronically between about 890 and 480Ma until thefinal basement of the South American Platform was attained[101] This occurred during the Lower Ordovician whereUnrug [102] suggested a mosaic of lithospheric fragmentslinked by several (accretionary collisional) Neoproterozoicmobile belts After amalgamation the Gondwana superconti-nent accumulated Paleozoic and Triassic-Jurassic sedimentsConcomitantly it was continuously and laterally accreted tothe western borders by successive orogenic belts until thePangea Formation [103 104] The main cratonic fragmentsdescending from ancestors of the Pangea for example theAmazonic and Rio de La Plata cratons were revoked andsmaller ancient crustal blocks formed at the Paraguay bound-aries [105] The magmatism was likely driven by the relativeextensional regimes derived from the relative movements ofthe ancient blocks (Figure 9) probably induced by counter-clockwise and clockwisemovements (North and South resp)hinged at about 20∘ and 24∘S [106]

The earthquake distribution and mechanisms [29] withhypocenters gt500 km and lt70 km respectively (Figure 9)coincide with the inferred Nazca plate subduction at theParaguay latitude (Figure 10) where the depth of the litho-spheric earthquakes together with the paleomagnetic results[38 95 107] delineates different rotational paths at about18ndash24∘S (ie Chaco-Pantanal Basin) These data indicateextensional subplate tectonics along the Andean system [95]coupled with the lineaments of lithospheric earthquakesversus the Atlantic system that parallels the Ponta GrossaArch and the lineaments of Rio Paraguay and Rio Pilcomayoalso clearly related to extensional environments [24 29 78]

Crucial to the genesis of the ASV magma types is thelink with the whole PAE system and with the geodynamicprocesses responsible for the opening of the South AtlanticAccording to Nurberg andMuller [108] the sea-floor spread-ing in the South Atlantic at ASV latitude started at about125ndash127Ma (ChronM4) but North of theWalvis-RioGranderidge (Figure 1(b)) the onset of the oceanic crust wouldbe younger for example 113Ma [109] Therefore the EarlyCretaceous alkaline and alkaline-carbonatite complexes fromASV (and PAE) are subcoeval with respect to the main floodtholeiites of the Parana Basin and occurred during the earlystages of rifting before the main continental separation

The origin of alkaline-carbonatitic magmatism in termsof plate tectonics is currently debated [77 110] and oftenconsidered in terms of models only In the present contextthe different westward angular velocity of the lithosphericfragments in the South American plate as defined by theldquosecond order plate boundariesrdquo (eg the Pylcomaio linea-ment [18]) as well as the different rotational trends at S19ndash24∘ Latitude would favour decompression and melting atdifferent times of variouslymetasomatized (wet spot) portionof the lithospheric mantle with variable isotopic signatures[24] Small-scale metasomatism is indicated by the differentsuites of mantle xenoliths and significant H-O-C and F

variations expected in themantle source from the occurrenceof the related carbonatites The latter imply lowering of thesolidus and along with an extensional tectonic favour themelting of the mantle and magma ascent This scenario alsoaccounts for the presence of Late Cretaceous to Tertiary sodicmagmatism in the PAE and in the Eastern Paraguay whererifting structures are evident (cf Figures 2 and 4)

7 Concluding Remarks

Geological and geophysical results show that the Mesozoic-Tertiary block-faulting tectonics in Eastern Paraguay isresponsible for NW-trending grabens (ASV and Amam-bay) fault systems and fault-controlled basins for exampleJejui-Aguaray-Guazu Asuncion-Encarnacion San Pedro (cfFigure 2)

Distinct magmatic events are widespread in theAsuncion-Sapucai-Villarrica graben the major extensionalstructure in Eastern Paraguay that is Early Cretaceoustholeiites and K-alkaline-carbonatitic complexes and dykesalong with Tertiary sodic magmatism It is expected thatbeneath a rifted continental area as ASV the lithosphericmantle may have been thinned and subjected to high heatflow This allowed the geotherm to intersect the peridotitesolidus in the presence of H

2O-CO

2-rich fluids and favour

the melt formations Under these conditions the derivedmelts may form dissolving most of the ldquovolatilerdquo phases andpercolating through a porous and deformed rock matrixinvaded the base of the lithosphere and favouredmetasomaticprocesses at different levels in the peridotitic lithospherewith the formation of amphibole andor phlogopite (ldquoveinedmantlerdquo of [82 83]) Notably the different tholeiitic (high-and low-Ti) K-alkaline suites (B-P and Ab-T) and sodicmagmatism with HK and LK xenoliths are consistentwith variously depleted lithospheric mantle at differenttimes pervasively and locally invaded by metasomatizingfluids andor melts Thereafter the newly formed veins(ldquoenriched componentrdquo) and peridotitic matrix (ldquodepletedcomponentrdquo) undervent different isotopic compositions withtime depending on their parentdaughter ratio (cf Figure 8)testifying heterogeneous mantle sources beneath ASV

Acknowledgments

This paper is dedicated to the memory of Enzo MichelePiccirillo who was an inspiration to the authors over manyyears of geological work in the region P Comin-Chiara-monti gratefully acknowledges CNR and MURST (ItalianAgencies) for the field financial support since 1981 andthe Department of Geosciences of the Trieste Universityfor the use of chemical laboratories where all the analyseswere performed Thanks are due to Exxon Co USDMAITAIPU and YACIRETA (Paraguayan Agencies) for theircollaborations and to engineer E Debernardi (deceased) andgeologists D Orue Luis Lucia and L A Martinez Thisresearch was also supported by grants (Procs 083807-4 and1050887-3) to C B Gomes from the Brazilian agency Fapesp


TheMsbenefit of the accurate revision ofKeith Bell and LalouGwalani

References

[1] V C Velazquez C B Gomes C Riccomini and J KirkldquoThe cretaceous alkaline dyke swarm in the central segment ofthe Asuncion rift eastern Paraguay its regional distributionmechanism of emplacement and tectonic significancerdquo Journalof Geological Research vol 2011 Article ID 946701 18 pages2011

[2] G Bellieni P C Chiaramonti L S Marques et al ldquoContinentalflood basalts from the central-western regions of the Paranaplateau (Paraguay and Argentina) petrology and petrogeneticaspectsrdquo Neues Jahrbuch fur Mineralogie Abhandlungen vol154 no 2 pp 111ndash139 1986

[3] E M Piccirillo and A J Melfi Eds The Mesozoic FloodVolcanism of the Parana Basin Petrogenetic and GeophysicalAspects IAG Sao Paulo Brazil 1988

[4] P Comin-Chiaramonti A Marzoli C De Barros Gomes et alldquoThe origin of post-Paleozoic magmatism in eastern ParaguayrdquoSpecial Paper of the Geological Society of America no 430 pp603ndash633 2007

[5] P Comin-Chiaramonti C B Gomes M Ernesto A Mar-zoli and C Riccomini Eastern Paraguay Post-PaleozoicMagmatism Large Igneous Province of the Month 2007httpwwwlargeigneousprovincesorg07jan

[6] P Comin-Chiaramonti A De Min V A V Girardi and ERuberti ldquoPost-Paleozoic magmatism in Angola and Namibiaa reviewrdquo inVolcanism and Evolution of the African Lithospherethe Geological Society of America L Beccaluva G Bianchiniand M Wilson M Eds Special Paper 478 pp 223ndash247 2011

[7] J D Fairhead and M Wilson ldquoPlate tectonic processes in theSouthAtlantic Ocean dowe need deepmantle plumesrdquo SpecialPaper of the Geological Society of America no 388 pp 537ndash5532005

[8] P V Zalan S Wolff M A Astolfi et al ldquoThe Parana basinBrazilrdquo in Interior Cratonic Basins MW Leighton D R KolataD F Oltz and J J Eidel Eds vol 51 of Memoir pp 601ndash708American Association of PetroleumGeology Tulsa Okla USA1990

[9] J J W Rogers R Unrug and M Sultan ldquoTectonic assembly ofGondwanardquo Journal of Geodynamics vol 19 no 1 pp 1ndash34 1995

[10] P Comin-Chiaramonti A Cundari E M Piccirillo et alldquoPotassic and sodic igneous rocks from Eastern Paraguay theirorigin from the lithospheric mantle and genetic relationshipswith the associated Parana flood tholeiitesrdquo Journal of Petrologyvol 38 no 4 pp 495ndash528 1997

[11] M Feng V D S Lee and M Assumpcao ldquoUpper mantlesrructure of South America from joint inversions of waveformsand fundamental mode group velocities of Rayleigh wavesrdquoJournal of Geophysical Research vol 112 pp 1ndash16 2007

[12] P Comin-Chiaramonti A Cundari JMDeGraff C B Gomesand E M Piccirillo ldquoEarly Cretaceous-Tertiary magmatism inEastern Paraguay (western Parana basin) geological geophysi-cal and geochemical relationshipsrdquo Journal of Geodynamics vol28 no 4-5 pp 375ndash391 1999

[13] P Comin-Chiaramonti ACundari C BGomes et al ldquoPotassicdyke swarm in the Sapucai Graben eastern Paraguay petro-graphical mineralogical and geochemical outlinesrdquo LITHOSvol 28 no 3ndash6 pp 283ndash301 1992

[14] C Riccomini V F Velazquez and C De Barros GomesldquoCenozoic lithospheric faulting in the Asuncion Rift easternParaguayrdquo Journal of South American Earth Sciences vol 14 no6 pp 625ndash630 2001

[15] Anschutz Co Geologic Map of Eastern Paraguay (1500000) FWiens Compiler Denver Colo USA 1981

[16] M D Druecker and S P Gay Jr ldquoMafic dyke swarms associatedwith Mesozoic rifting in Eastern Paraguay South Americardquo inMafic Dyke Swarms Geological Association of Canada H CHalls and A R Fahrig Eds pp 187ndash193 1987

[17] N Ussami A Kolisnyk M I B Raposo F J F FerreiraE C Molina and M Ernesto ldquoDetectabilitade magnetica dediques do Arco de Ponta Grossa um estudo integrado demagnetometria terrestreaerea e magnetismo de rochardquo RevistaBrasileira de Geociencias vol 21 pp 317ndash327 1994

[18] J M de Graff ldquoLate Mesozoic crustal extension and riftingon the western edge of the Parana Basin Paraguayrdquo GeologicalSociety of America Abstracts with Programs vol 17 p 560 1985

[19] PHOTO GRAVITY Co Regional Bouguer Gravity Data andStation Location Map of the Paraguay (Scale 12000000)Archivo DRM-MOPC Asuncion Paraguay 1991

[20] D S Hutchinson ldquoGeology of the Apa Highrdquo Internal ReportTAC Asuncion Paraguay 1979

[21] F Wiens ldquoMapa geologica de la region oriental Republicadel Paraguay escala 15000002rdquo Simposio Recursos NaturalesParaguay Asuncion p 9 1982

[22] R A Livieres and H Quade ldquoDistribucion regional y asen-tamiento tectonico de los complejos alcalinos del ParaguayrdquoZentralblatt fur Geologie und Palaontologie vol 7 pp 791ndash8051987

[23] A Kanzler ldquoThe southern Precambrian in Paraguay Geologicalinventory and age relationsrdquo Zentralblatt fur Geologie undPalaontologie vol 7 pp 753ndash765 1987

[24] P Comin-Chiaramonti and C B Gomes Eds Alkaline Mag-matism in Central-Eastern Paraguay Relationships with CoevalMagmatism in Brazil EduspFapesp Sao Paulo Brazil 1996

[25] P R Renne M Ernesto I G Pacca et al ldquoThe age of Paranaflood volcanism rifting of gondwanaland and the Jurassic-Cretaceous boundaryrdquo Science vol 258 no 5084 pp 975ndash9791992

[26] P R Renne D F Mertz W Teixeira H Ens and M RichardsldquoGeochronologic constraints on magmatic and tectonic evolu-tion of the Parana ProvincerdquoThe American Geophysical Unionvol 74 abstract p 553 1993

[27] P R Renne K Deckart M Ernesto G Feraud and E MPiccirillo ldquoAge of the Ponta Grossa dike swarm (Brazil) andimplications to Parana flood volcanismrdquo Earth and PlanetaryScience Letters vol 144 no 1-2 pp 199ndash211 1996

[28] C B Gomes P Comin-Chiaramonti and V F Velazquez ldquoTheMesoproterozoic rhyolite occurrences of Fuerte Olimpo andFuerte San Carlos Northern Paraguayrdquo Revista Brasileira DeGeociencias vol 30 pp 785ndash788 2000

[29] J Berrocal and C Fernandes ldquoSeismicity in Paraguay andneighbouring regionsrdquo in Alkaline Magmatism in Central-Eastern Paraguay Relationships with Coevalmagmatism inBrazil P Comin-Chiaramonti and C B Gomes Eds pp 57ndash66 EduspFapesp Sao Paulo Brazil 1996

[30] A Tommasi and A Vauchez ldquoContinental rifting parallel toancient collisional belts an effect of the mechanical anisotropyof the lithospheric mantlerdquo Earth and Planetary Science Lettersvol 185 no 1-2 pp 199ndash210 2001


[31] P F Green I R Duddy P OrsquoSullivan K A Hegarty P Comin-Chiaramonti and C B Gomes ldquoMesozoic potassic magma-tism from the Asuncion-Sapucai graben apatite fission trackanalysis of the Acahai suite and implication for hydrocarbonexplorationrdquo Geochimica Brasiliensis vol 5 pp 79ndash88 1991

[32] K A Hegarty I R Duddy and P F Green ldquoThe thermalhistory in around the Parana basin using apatite fission trackanalysis-implications for hydrocarbon occurrences and basinformationrdquo inAlkalinemagmatism inCentral-Eastern ParaguayRelationships with Coevalmagmatism in Brazil P Comin-Chiaramonti and C B Gomes Eds pp 67ndash84 EduspFapespSao Paulo Brazil 1996

[33] P Comin-Chiaramonti A De Min and C B Gomes ldquoMag-matic rock-types from the Asuncion-Sapucai graben descrip-tion of the occurrences and petrographical notesrdquo in AlkalineMagmatism in Central-Eastern Paraguay Relationships withcoevalmagmatism in Brazil P Comin-Chiaramonti and C BGomes Eds pp 275ndash330 EduspFapesp Sao Paulo Brazil1996

[34] P Comin-Chiaramonti A De Min and A Marzoli ldquoMag-matic rock-types from the Asuncion-Sapucai graben chemicalanalysesrdquo in Alkaline Magmatism in Central-Eastern ParaguayRelationships with coevalmagmatism in Brazil P Comin-Chiaramonti and C B Gomes Eds pp 331ndash387 EduspFapespSao Paulo Brazil 1996

[35] P Comin-Chiaramonti A Cundari and G Bellieni ldquoMin-eral analyses of alkaline rock-types from the Asuncion-Sapucai grabenrdquo in AlkalIne Magmatism in Central-EasternParaguay Relationships with coevalmagmatism In Brazil PComin-Chiaramonti and C B Gomes Eds pp 389ndash458EduspFapesp Sao Paulo Brazil 1996

[36] P Comin-Chiaramonti A Cundari A De Min C B Gomesand V F Velazquez ldquoMagmatism in Eastern Paraguay occur-rence and petrographyrdquo in Alkaline Magmatism in Central-Eastern Paraguay Relationships with coevalmagmatism inBrazil P Comin-Chiaramonti and C B Gomes Eds pp 103ndash122 EduspFapesp Sao Paulo Brazil 1996

[37] J M de Graff S P Gay Jr and D Orue ldquoInterpretaciongeofısica and geologica del Valle de Ypacaraı (Paraguay) y suformacionrdquo Revista de la Asociacion Geologica Argentina vol36 no 3 pp 240ndash256 1981

[38] M Ernesto P Comin-Chiaramonti C B Gomes A MC Castillo and V F Velazquez ldquoPalaeomagnetic data fromthe central alkaline province Eastern Paraguayrdquo in AlkalineMagmatism in Central-Eastern Paraguay Relationships withcoevalmagmatism in Brazil P Comin-Chiaramonti and C BGomes Eds pp 85ndash102 EduspFapesp Sao Paulo Brazil 1996

[39] H de La Roche ldquoClassification and nomenclature des rochesignees un essai de restauration de la convergence entresystematique quantitative typologie drsquousage et modelisationgenetiquerdquo Bulletin de la Societe Geologique de France vol 8pp 337ndash353 1986

[40] R P Le Maitre A Classification of Igneous Rocks and Glossary ofTerms Blackwell Oxford UK 1989

[41] A Streckeisen ldquoTo each plutonic rock its proper namerdquo EarthScience Reviews vol 12 no 1 pp 1ndash33 1976

[42] C B Gomes P Comin-Chiaramonti A DeMin et al ldquoAtivi-dade filoniana asociada ao complexo alcalino de SapukaiParaguay Orientalrdquo Geochimica Brasiliensis vol 3 pp 93ndash1141989

[43] G Bellieni P Comin-Chiaramonti L S Marques et al ldquoPet-rogenetic aspects of acid and basaltic lavas from the Parana

plateau (Brazil) geological mineralogical and petrochemicalrelationshipsrdquo Journal of Petrology vol 27 no 4 pp 915ndash9441986

[44] P Comin-Chiaramonti C B Gomes P Censi A DeMin SRotolo andV F Velazquez ldquoGeoquimica domagmatismoPost-Paleozoico no Paraguai Centro-OrientalrdquoGeochimica Brasilien-sis vol 7 pp 19ndash34 1993

[45] G Bellieni P Comin-Chiaramonti L S Marques et al ldquoHigh-and low-TiO

2flood basalts of Parana plateau (Brazil) petrology

petrogenetic aspects and mantle source relationshipsrdquo NeuesJahrbuch fur Mineralogie Abhandlungen vol 150 pp 273ndash3061984

[46] E M Piccirillo G Bellieni P Comin-Chiaramonti et alldquoContinental flood volcanism from the Paranarsquo Basin (Brazil)rdquoin Continental Flood Volcanism J D McDougal Ed pp 195ndash238 Kluver Academic London UK 1988

[47] E M Piccirillo L Civetta R Petrini et al ldquoRegional variationswithin the Parana flood basalts (southern Brazil) evidence forsubcontinental mantle heterogeneity and crustal contamina-tionrdquo Chemical Geology vol 75 no 1-2 pp 103ndash122 1989

[48] P Comin-Chiaramonti P Censi A Cundari and C B GomesldquoA silico-beforsitic flow from the Sapucai Complex (central-eastern Paraguay)rdquo Geochimica Brasiliensis vol 6 no 1 pp 87ndash91 1992

[49] P Comin-Chiaramonti A Cundari C BGomes et al ldquoMineralchemistry and its genetic significance of major and accessoryminerals from a potassic dyke swarm in the Sapucai grabenCentral-Eastern Paraguayrdquo Brasileira Geoquımica vol 4 pp175ndash206 1990

[50] G Faure Origin of Igneous Rocks The Isotopic EvidenceSpringer Berlin Germany 2001

[51] A D Edgar ldquoRole of subduction in the genesis of leucite-bearing rocks discussionrdquo Contributions to Mineralogy andPetrology vol 73 no 4 pp 429ndash431 1980

[52] A Cundari and A K Ferguson ldquoSignificance of the pyrox-ene chemistry from leucite-bearing and related assemblagesrdquoTMPM Tschermaks Mineralogische und Petrographische Mit-teilungen vol 30 no 3 pp 189ndash204 1982

[53] P Comin-Chiaramonti F Lucassen V A V Girardi A DeMin and C B Gomes ldquoLavas and their mantle xenolithsfrom intracratonic eastern Paraguay (South America Platform)and andean domain NW-Argentina a comparative reviewrdquoMineralogy and Petrology vol 98 no 1-2 pp 143ndash165 2010

[54] G DeMarchi P Comin-Chiaramonti P DeVito S Sinigoi andA M C Castillo ldquoLherzolite-dunite xenoliths from EasternParaguay petrological constraints to mantle metasomatismrdquo inThe Mesozoic Flood Volcanism of the Paranrsquo Basin Petrogeneticand Geophysical Aspects E M Piccirillo and A J Melfi Edspp 207ndash228 IAG Sao Paulo Brazil 1988

[55] P Comin-Chiaramonti L Civetta E M Piccirillo et al ldquoTer-tiary nephelinitic magmatism in eastern Paraguay petrologySr-Nd isotopes and genetic relationshipswith associated spinel-peridotite xenolithsrdquo European Journal of Mineralogy vol 3 no3 pp 507ndash525 1991

[56] P Comin-Chiaramonti F Princivalle V A V Girardi C BGomes A Laurora and R Zanetti ldquoMantle xenoliths fromNemby Eastern Paraguay O-Sr-Nd isotopes trace elementsand crystal chemistry of hosted clinopyroxenesrdquo Periodico diMineralogia vol 70 pp 205ndash230 2001

[57] J Wang K H Hattori R Kilian and C R Stern ldquoMeta-somatism of sub-arc mantle peridotites below southernmost


South America reduction of fO2by slab-meltrdquo Contributions

to Mineralogy and Petrology vol 153 no 5 pp 607ndash624 2007[58] M F Roden F A Frey and D M Francis ldquoAn example of

consequentmantlemetasomatism in peridotite inclusions fromNunivak Island Alaskardquo Journal of Petrology vol 25 no 2 pp546ndash577 1984

[59] S Y OrsquoReilly andW L Griffin ldquoMantle metasomatism beneathwestern Victoria Australia I Metasomatic processes in Cr-diopside lherzolitesrdquoGeochimica et Cosmochimica Acta vol 52no 2 pp 433ndash447 1988

[60] F J Spera ldquoCarbon dioxide in petrogenesis III role of volatilesin the ascent of alkaline magma with special reference toxenolith-bearing mafic lavasrdquo Contributions to Mineralogy andPetrology vol 88 no 3 pp 217ndash232 1984

[61] F A Frey and D H Green ldquoThemineralogy geochemistry andorigin of lherzolite inclusions inVictorian basaniterdquoGeochimicaet Cosmochimica Acta vol 38 pp 1023ndash1050 1979

[62] D K Koustpoulos ldquoMelting of the shallow upper mantle a newperspectiverdquo Journal of Perology vol 32 pp 671ndash699 1991

[63] G Rivalenti R Vannucci E Rampone et al ldquoPeridotiteclinopyroxene chemistry reflects mantle processes rather thancontinental versus oceanic settingsrdquo Earth and Planetary Sci-ence Letters vol 139 no 3-4 pp 423ndash437 1996

[64] P R A Wells ldquoPyroxene thermometry in simple and complexsystemsrdquoContributions to Mineralogy and Petrology vol 42 pp109ndash121 1977

[65] J Fabries ldquoSpinel-olivine geothermometry in peridotites fromultramafic complexesrdquo Contributions to Mineralogy and Petrol-ogy vol 69 pp 329ndash336 1979

[66] J C Mercier ldquoSingle-pyroxene geothermometry and geo-barometryrdquo The American Journal of Sciences vol 61 no 7-8pp 603ndash615 1980

[67] J C C Mercier V Benoit and J Girardeau ldquoEquilibrium stateof diopside-bearing harzburgites from ophiolites geobaromet-ric and geodynamic implicationsrdquo Contributions to Mineralogyand Petrology vol 85 no 4 pp 391ndash403 1984

[68] G Sen F A Frey N Shimizu and W P Leeman ldquoEvolutionof the lithosphere beneath Oahu Hawaii rare earth elementabundances in mantle xenolithsrdquo Earth and Planetary ScienceLetters vol 119 no 1-2 pp 53ndash69 1993

[69] H Chiba T Chack R N Clayton and J Goldsmith ldquoOxygenisotope fractionations involving diopside forsterite magnetiteand calcite application to geothermometryrdquo Geochimica etCosmochimica Acta vol 53 pp 2985ndash2989 1989

[70] D Mattey D Lowry and C Macpherson ldquoOxygen isotopecomposition of mantle peridotiterdquo Earth and Planetary ScienceLetters vol 128 no 3-4 pp 231ndash241 1994

[71] T K Kyser ldquo1990 Stable isotopes in the continental lithosphericmantlerdquo inContinental Mantle M AMenzies Ed pp 127ndash156Oxford Clarendon Press Oxford UK 1990

[72] T K Kyser J ROrsquoNeil and I S E Carmichael ldquoOxygen isotopethermometry of basic lavas and mantle nodulesrdquo Contributionsto Mineralogy and Petrology vol 77 no 1 pp 11ndash23 1981

[73] F Princivalle M Tirone and P Comin-Chiaramonti ldquoClinopy-roxenes frommetasomatized spinel-peridotitemantle xenolithsfrom Nemby (Paraguay) crystal chemistry and petrologicalimplicationsrdquoMineralogy and Petrology vol 70 no 1-2 pp 25ndash35 2000

[74] F Castorina P Censi P Comin-Chiaramonti et al ldquoCarbon-atites from Eastern Paraguay and genetic relationships withpotassic magmatism C O Sr and Nd isotopesrdquoMineralogy andPetrology vol 61 no 1ndash4 pp 237ndash260 1998

[75] P Antonini M Gasparon P Comin-Chiaramonti and C BGomes ldquoPost-palaeozoic magmatism in Eastern paraguay Sr-Nd-Pb isotope compositionsrdquo inMesozoic to Cenozoic AlkalineMagmatism in the Brazilian Platform P Comin-Chiaramontiand C B Gomes Eds pp 57ndash70 EdUSP Fapesp Sao PauloBrazil 2005

[76] D Mckenzie and R K Orsquonions ldquoThe source regions of oceanisland basaltsrdquo Journal of Petrology vol 36 no 1 pp 133ndash1591995

[77] S R Hart and A Zindler ldquoConstraints on the nature andthe development of chemical heterogeneities in the mantlerdquoin Mantle Convection Plate Tectonics and Global Dynamics WR Peltier Ed pp 261ndash388 Gordon and Breach Sciences NewYork NY USA 1989

[78] P Comin-Chiaramonti C B Gomes and Eds Mesozoic toCenozoic AlkalineMagmatism in the Brazilian Platform EdUSPFapesp Sao Paulo Brazil 2005

[79] R W Carlson S Esperanca and D P Svisero ldquoChemical andOs isotopic study of Cretaceous potassic rocks from SouthernBrazilrdquo Contributions to Mineralogy and Petrology vol 125 no4 pp 393ndash405 1996

[80] M A Menzies Ed Continental Mantle Oxford ClarendonPress 1990

[81] B L Weaver ldquoThe origin of ocean island basalt end-membercompositions trace element and isotopic constraintsrdquo Earthand Planetary Science Letters vol 104 no 2ndash4 pp 381ndash397 1991

[82] S Foley ldquoPetrological characterization of the source com-ponents of potassic magmas geochemical and experimentalconstraintsrdquo LITHOS vol 28 no 3ndash6 pp 187ndash204 1992

[83] S Foley ldquoVein-plus-wall-rockmeltingmechanisms in the litho-sphere and the origin of potassic alkaline magmasrdquo LITHOSvol 28 no 3ndash6 pp 435ndash453 1992

[84] C J Hawkesworth M S M Mantovani P N Taylor andZ Palacz ldquoEvidence from the Parana of south Brazil for acontinental contribution to Dupal basaltsrdquo Nature vol 322 no6077 pp 356ndash359 1986

[85] J K Meen J C Ayers and E J Fregeau ldquoA model of mantlemetasomatism by carbonated alkaline melts trace element andisotopic compositions of mantle source regions of carbonatiteand other continental igneous roksrdquo in Carbonatites Genesisand Evolution K Bell Ed pp 464ndash499 Unwin HymanLondon UK 1989

[86] S-S Sun and W F McDonough ldquoChemical and isotopic sys-tematics of oceanic basalts implications formantle compositionand processesrdquo in Magmatism in the Ocean Basins A DSaunders and M J Norry Eds Special Paper 42 pp 313ndash345Geological Society of London 1989

[87] P Comin-Chiaramonti F Castorina A Cundari R Petrini andC B Gomes ldquoDykes and sills fromEastern paraguay Sr andNdisotope systematicrdquo in IDC-3 Physics and Chemistry of DykesG Baer andAHeiman Eds pp 267ndash278 Balkema RotterdamThe Netherlands 1995

[88] P Comin-Chiaramonti C B Gomes A Cundari F Castorinaand P Censi ldquoA review of carbonatitic magmatism in theParana-Angola-Etendeka (Pan) systemrdquo Periodico di Mineralo-gia vol 76 pp 25ndash78 2007

[89] P Comin-Chiaramonti C B Gomes P Censi et al ldquoAlkalinecomplexes from the alto paraguay province at the border ofBrazil (Mato Grosso do Sul State) and Paraguayrdquo in MesozoicTo Cenozoic Alkaline Magmatism in the Brazilian Platform PComin-Chiaramonti and C B Gomes Eds pp 71ndash148 Edusp-Fapesp SaoPaulo Brazil 2005


[90] C J Hawkesworth K Gallagher S Kelley et al ldquoParana mag-matism and the opening of the South Atlanticrdquo in Magmatismand the Causes of Continental Break-Up B C Storey Ed vol68 pp 221ndash240 Geological Society of London 1992

[91] S Turner M Regelous S Kelley C Hawkesworth and MMantovani ldquoMagmatism and continental break-up in the SouthAtlantic high precision 40Ar39Ar geochronologyrdquo Earth andPlanetary Science Letters vol 121 no 3-4 pp 333ndash348 1994

[92] D W Peate ldquoThe parana-etendeka provincerdquo in Large IgneuosProvince Continetal Oceanic Planetary Flood Volcanism JMahoney and M F Coffin Eds pp 217ndash245 American Geo-physcial Union Washington DC USA 1992

[93] D W Peate and C J Hawkesworth ldquoLithospheric to astheno-spheric transition in low-Ti flood basalts from southern ParanaBrazilrdquo Chemical Geology vol 127 no 1ndash3 pp 1ndash24 1996

[94] A J Erlank F G Waters C J Hawkesworth et al ldquoEvidencefor mantle metasomatism in peridotite nodules from the Kim-berley pipes South Africardquo in Mantle Metasomatism M AMenzies and C J Hawkesworth Eds pp 221ndash309 AcademicPress London UK 1987

[95] D E Randall ldquoA new Jurassic-Recent apparent polar wanderpath for South America and a review of central Andean tectonicmodelsrdquo Tectonophysics vol 299 no 1ndash3 pp 49ndash74 1998

[96] O Gudmundsson and M Sambridge ldquoA Regionalized UpperMantle (RUM) seismic modelrdquo Journal of Geophysical ResearchB vol 103 no 4 pp 7121ndash7136 1998

[97] F Lucassen R Becchio H G Wilke et al ldquoProterozoic-Paleozoic development of the basement of the Central Andes(18-26∘S) - Amobile belt of the South American cratonrdquo Journalof South American Earth Sciences vol 13 no 8 pp 697ndash7152000

[98] J H Laux M M Pimentel E L Dantas R Armstrong and SL Junges ldquoTwo neoproterozoic crustal accretion events in theBrasılia belt central Brazilrdquo Journal of South American EarthSciences vol 18 no 2 pp 183ndash198 2005

[99] H K Liu S S Gao P G Silver and Y Zhang ldquoMantle layeringacross central South Americardquo Journal of Geophysical Researchvol 108 no 1 p 2510 2003

[100] J C Van Decar D E James and M Assumpcao ldquoSeismicevidence for a fossil mantle plume beneath South America andimplications for plate driving forcesrdquo Nature vol 378 no 6552pp 25ndash31 1995

[101] M S M Mantovani M C L Quintas W Shukowsky and B Bde Brito Neves ldquoDelimitation of the Paranapanema proterozoicblock a geophysical contributionrdquo Episodes vol 28 no 1 pp18ndash22 2005

[102] R Unrug ldquoThe Assembly of Gondwanalandrdquo Episodes vol 19pp 11ndash20 1996

[103] U G Cordani K Sato W Teixeira C C G Tassinari and MA S Basei ldquoCrustal evolution of the South American platformrdquoin Tectonic Evolution of South America 31st International Geo-logical Congress Rio De Janeiro U G Cordani E J Milani AA Thomaz Filho and D A Campos Eds pp 19ndash40 2000

[104] U G Cordani C C G Tassinari and D R Rolim ldquoThebasement of the Rio Apa Craton in Mato Grosso do Sul (Brazil)and northern Paraguay a geochronological correlationwith thetectonic provinces of the south-western Amazonian Cratonrdquo inGondwana Conference Abstracts Volume Mendoza Argentinapp 1ndash12 2005

[105] A Kroner and U Cordani ldquoAfrican southern Indian and SouthAmerican cratons were not part of the Rodinia superconti-nent evidence from field relationships and geochronologyrdquoTectonophysics vol 375 no 1ndash4 pp 325ndash352 2003

[106] C B Prezzi and R N Alonso ldquoNew paleomagnetic data fromthe northern Argentine Puna central Andes rotation patternreanalyzedrdquo Journal of Geophysical Research B vol 107 no 2pp 1ndash18 2002

[107] A E Rapalini ldquoThe accretionary history of southern SouthAmerica from the latest Proterozoic to the Late Palaeozoicsome palaeomagnetic constraintsrdquo Geological Society vol 246pp 305ndash328 2005

[108] D Nurberg and R D Muller ldquoThe tectonic evolution of SouthAtlantic from Late Jurassic to presentrdquo Tectonophysics vol 191pp 27ndash43 1991

[109] H K Chang R O Kowsmann and A M F de FigueiredoldquoNew concepts on the development of east Brazilian marginalbasinsrdquo Episodes vol 11 no 3 pp 194ndash202 1988

[110] W S Holbrook and P B Kelemen ldquoLarge igneous province onthe US atlantic margin and implications for magmatism duringcontinental breakuprdquo Nature vol 364 no 6436 pp 433ndash4361993

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

ClimatologyJournal of

EcologyInternational Journal of


EarthquakesJournal of


Hindawi Publishing Corporationhttpwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2014

Mining


Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal of

Geophysics

OceanographyInternational Journal of


Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering


GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Atmospheric SciencesInternational Journal of


OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in


MineralogyInternational Journal of


MeteorologyAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Geological ResearchJournal of


Geology Advances in


SouthAmerica

EPAsuncion

Low Ti

Africa

SouthAtlantic

Dykes

High Ti

Rio de Janeiro

(a)

Moccedilamedes Arch

50∘ W

10∘ S

20∘ S

30∘ S

40∘ W 20∘W

10∘S

20∘S

BrazilAraguaia-Paranaıba-

Cabo Frio

Ponta Grossa ArchRio PiquirıTorres SynclineRio Grande Arch

RioGrande

RiseWalvis

Ridge

Angola

Damara Belt

Namibia

Relative motion

as from flow lines

South America

absolute motion

Africa

abso

lute m

otion

MAR motion

(b)

Figure 1 (a) Sketch map of the Parana-Angola-Etendeka system [3] where the arrows indicate the occurrences of the main dyke swarmsThe basaltic lavas are subdivided into broad high- and low-Ti groups and late-stage rhyolites (yellow fields) EP Eastern Paraguay (b) Mainlineaments in the Parana-Angola-Etendeka system (PAE) western Gondwana at ca 110Ma (modified after [6]) corresponding to the mainlineaments of the alkaline and alkaline-carbonatitic complex Inset vector diagram showing relationships among absolute plate motionsrelative motions and motion of the Mid-Atlantic Ridge (MAR after [7])

(ASV) graben (3) petrography and petrochemistry of themagmatic rock-types (and the associated mantle xenoliths)from ASV (4) the most important geochemical and Sr-Ndisotopic features of the magmatism (5) the petrogenesis andgeodynamic implications

2 Eastern Paraguay Geological Outlines andGeophysical Aspects

Eastern Paraguay shows a complex block-faulted structurebetween the southern Precambrian tip of the AmazonianCraton (Apa block) and the northern one of the Rio de laPlata Craton (Caacupu high Figure 2) This intercratonicarea including the westernmost fringe of the Parana Basin(PB) represents an undeformed basin along the westernGondwana (Figure 1) where the sedimentation started inCambrian times was topped by Early Cretaceous tholeiiticbasalts of the Serra Geral Formation [8 9] and followed byyounger sedimentation (Figure 2)

Moreover it should be also noted that Eastern Paraguaylies along the former western margin of the Gondwanabounded by an anticlinal structure established since EarlyPaleozoic the Asuncion Arch which separates the ParanaBasin (East) from the Gran Chaco Basin (West) [10] PBshows a high-velocity upper mantle ldquolidrdquo with a maximumS-wave velocity of 47 kms (Moho 37 km depth) with anunresolved low-velocity zone to a depth of at least 200 km [11]Between the two blocks that is Apa andCaacupu of Figure 2Eastern Paraguay was subjected to NE-SW-trending crustalextension during Late Jurassic-Early Cretaceous probablyrelated to the western Gondwana breakup (Figure 1 [10 12]

and therein references) NW-SE trending faults parallelingthe dominant orientation of Mesozoic alkaline and tholeiiticdykes reflect this type of structure [13 14]

From the aeromagnetic survey [15 16] the linear mag-netic anomalies trend mainly N40-45W (Figure 3) Theseanomalies have been interpreted as resulting from EarlyCretaceous tholeiitic dyke swarms [16] but field evidencedoes not support this hypothesis Most magnetic anomaliescorrespond to older Precambrian tectonic lineament [17]The Landsat lineaments trending mainly NE and EW maytherefore reflect tectonic lineaments from the basement [18]

The Bouguer gravity map (Figure 3) consists of prevail-ing NW-trending gravity ldquohighsrdquo and ldquolowsrdquo that representshallow to exposed basement and sedimentary basins respec-tively [19]The boundaries between gravity highs and lows aregenerally marked by step gradients that may reflect abruptbasement offsets along faults or basement dip changes bycrustal warping Notably the gravity lows and highs parallelthe dominant NW attitude of the magnetic lineaments withpost-Palaeozoic magmatism (both tholeiitic and alkaline)associated with gravity lows Therefore the ASV representsthe most important geological structure of the region (seelater)

Notably the present seismic activity (earthquakes withhypocenters lt70 km) indicates that the NW-trending faultsystems continue up to present day that is the Pilcomayolineament (inset of Figure 3) also aligned with the Piquirılineament and the Torres syncline (Figure 1(b))

In conclusion the resulting structural pattern con-trolled the development of grabens or semigrabens as aresponse to NE-SW-directed extension and continued evolv-ing into Cenozoic times [12 24] According to Tommasi and


Fuerte Olimpo1341

Alto Paraguay241

Rio Apa139

22∘S

26∘S

55∘W57 ∘W

Valle-mıApa river

Apablock Amambay

Cerro Chiriguelo139

Cerro Sarambı

San Carlos 1341



Gran

Cha

coBa

sin San Pedro low

Paraguay

Asuncion

Asuncion

58Pilcomayo river

Argentin

a

ASV

Central 130-127

acutehigh


132

SJB


ragu

ay ri

ver

100 kmArgentina

Para

na B

asin

Encarnacion 133

Ciudad delEste133

Para

na B

asin

1

2

3

4

5

6

7

8

9

10

11

12

13

14

SJB

Caacup998400e



55∘W

minus30


26∘S

23∘S

57 ∘W

57 ∘W

55∘W

25∘S

minus60

minus40

minus60

minus60

minus5010

100

10

20

0

minus40minus30

0

minus10minus20

minus40

100

10

20

30

10


010

BV

PJC

MB

SE

A

Asuncion

NL

S

R










18



Major faults

N

0 10 20

(km)

Chaco

River

E

C

F

GH

B

DA

Asuncion

Ypacaraı valley

Yaguaron

Paraguarı

Carapegua

Acahay

22

21

20

I

JK

L

La Colmena

14

1210

11

13

M8

9

2

31

4

56

7

Villarrica

Sapucai

Caballero

Ybytyruzuhills



17

Ybycuı

15

19








(I)(II)

(III)

K2O

K2O

15

10

5

0

15

10

5

0

0 5 10Na2O

Na2O

Sodic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

0 5 10

Sodic

32

1

4

5

67

89

1011

R2

R2

2000

1000

Intrusiverocks

R1

R1

R1

R1

SuiteNa K

VolcanicrocksSuite

Suite

Na K

Na K

1000

2000

1000

2000

R2Dykes

200010000minus1000minus2000

Foid-bearingsyenite



Foid syenite

Foid

monzosyenite

Foid

mon

zodi

orite

Foid

mon

zoga

bbro

AB-T

B-P

A P

F

B-P

AB-T



K-alkaline BP


Na-alkaline

3000

1000

Ankaratrite

Basanite

Alkali

basalt


Trachyandesite

Trachybasalt



Andesite-basalt

R2

SGN

N

200010000minus1000minus2000

Foidolite


2= 6Ca + Mg + Al





2O and Na








2





2



















2SiO4-KAlSiO

4[10 13 51] sug-






Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Fuerte Olimpo1341

Alto Paraguay241

Rio Apa139

22∘S

26∘S

55∘W57 ∘W

Valle-mıApa river

Apablock Amambay

Cerro Chiriguelo139

Cerro Sarambı

San Carlos 1341



Gran

Cha

coBa

sin San Pedro low

Paraguay

Asuncion

Asuncion

58Pilcomayo river

Argentin

a

ASV

Central 130-127

acutehigh


132

SJB


ragu

ay ri

ver

100 kmArgentina

Para

na B

asin

Encarnacion 133

Ciudad delEste133

Para

na B

asin

1

2

3

4

5

6

7

8

9

10

11

12

13

14

SJB

Caacup998400e



55∘W

minus30


26∘S

23∘S

57 ∘W

57 ∘W

55∘W

25∘S

minus60

minus40

minus60

minus60

minus5010

100

10

20

0

minus40minus30

0

minus10minus20

minus40

100

10

20

30

10


010

BV

PJC

MB

SE

A

Asuncion

NL

S

R










18



Major faults

N

0 10 20

(km)

Chaco

River

E

C

F

GH

B

DA

Asuncion

Ypacaraı valley

Yaguaron

Paraguarı

Carapegua

Acahay

22

21

20

I

JK

L

La Colmena

14

1210

11

13

M8

9

2

31

4

56

7

Villarrica

Sapucai

Caballero

Ybytyruzuhills



17

Ybycuı

15

19








(I)(II)

(III)

K2O

K2O

15

10

5

0

15

10

5

0

0 5 10Na2O

Na2O

Sodic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

0 5 10

Sodic

32

1

4

5

67

89

1011

R2

R2

2000

1000

Intrusiverocks

R1

R1

R1

R1

SuiteNa K

VolcanicrocksSuite

Suite

Na K

Na K

1000

2000

1000

2000

R2Dykes

200010000minus1000minus2000

Foid-bearingsyenite



Foid syenite

Foid

monzosyenite

Foid

mon

zodi

orite

Foid

mon

zoga

bbro

AB-T

B-P

A P

F

B-P

AB-T



K-alkaline BP


Na-alkaline

3000

1000

Ankaratrite

Basanite

Alkali

basalt


Trachyandesite

Trachybasalt



Andesite-basalt

R2

SGN

N

200010000minus1000minus2000

Foidolite


2= 6Ca + Mg + Al





2O and Na








2





2



















2SiO4-KAlSiO

4[10 13 51] sug-






Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


55∘W

minus30


26∘S

23∘S

57 ∘W

57 ∘W

55∘W

25∘S

minus60

minus40

minus60

minus60

minus5010

100

10

20

0

minus40minus30

0

minus10minus20

minus40

100

10

20

30

10


010

BV

PJC

MB

SE

A

Asuncion

NL

S

R










18



Major faults

N

0 10 20

(km)

Chaco

River

E

C

F

GH

B

DA

Asuncion

Ypacaraı valley

Yaguaron

Paraguarı

Carapegua

Acahay

22

21

20

I

JK

L

La Colmena

14

1210

11

13

M8

9

2

31

4

56

7

Villarrica

Sapucai

Caballero

Ybytyruzuhills



17

Ybycuı

15

19








(I)(II)

(III)

K2O

K2O

15

10

5

0

15

10

5

0

0 5 10Na2O

Na2O

Sodic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

0 5 10

Sodic

32

1

4

5

67

89

1011

R2

R2

2000

1000

Intrusiverocks

R1

R1

R1

R1

SuiteNa K

VolcanicrocksSuite

Suite

Na K

Na K

1000

2000

1000

2000

R2Dykes

200010000minus1000minus2000

Foid-bearingsyenite



Foid syenite

Foid

monzosyenite

Foid

mon

zodi

orite

Foid

mon

zoga

bbro

AB-T

B-P

A P

F

B-P

AB-T



K-alkaline BP


Na-alkaline

3000

1000

Ankaratrite

Basanite

Alkali

basalt


Trachyandesite

Trachybasalt



Andesite-basalt

R2

SGN

N

200010000minus1000minus2000

Foidolite


2= 6Ca + Mg + Al





2O and Na








2





2



















2SiO4-KAlSiO

4[10 13 51] sug-






Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


18



Major faults

N

0 10 20

(km)

Chaco

River

E

C

F

GH

B

DA

Asuncion

Ypacaraı valley

Yaguaron

Paraguarı

Carapegua

Acahay

22

21

20

I

JK

L

La Colmena

14

1210

11

13

M8

9

2

31

4

56

7

Villarrica

Sapucai

Caballero

Ybytyruzuhills



17

Ybycuı

15

19








(I)(II)

(III)

K2O

K2O

15

10

5

0

15

10

5

0

0 5 10Na2O

Na2O

Sodic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

0 5 10

Sodic

32

1

4

5

67

89

1011

R2

R2

2000

1000

Intrusiverocks

R1

R1

R1

R1

SuiteNa K

VolcanicrocksSuite

Suite

Na K

Na K

1000

2000

1000

2000

R2Dykes

200010000minus1000minus2000

Foid-bearingsyenite



Foid syenite

Foid

monzosyenite

Foid

mon

zodi

orite

Foid

mon

zoga

bbro

AB-T

B-P

A P

F

B-P

AB-T



K-alkaline BP


Na-alkaline

3000

1000

Ankaratrite

Basanite

Alkali

basalt


Trachyandesite

Trachybasalt



Andesite-basalt

R2

SGN

N

200010000minus1000minus2000

Foidolite


2= 6Ca + Mg + Al





2O and Na








2





2



















2SiO4-KAlSiO

4[10 13 51] sug-






Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


(I)(II)

(III)

K2O

K2O

15

10

5

0

15

10

5

0

0 5 10Na2O

Na2O

Sodic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

Transit

ional

Potas

sic

Hig

hly p

otas

sic

0 5 10

Sodic

32

1

4

5

67

89

1011

R2

R2

2000

1000

Intrusiverocks

R1

R1

R1

R1

SuiteNa K

VolcanicrocksSuite

Suite

Na K

Na K

1000

2000

1000

2000

R2Dykes

200010000minus1000minus2000

Foid-bearingsyenite



Foid syenite

Foid

monzosyenite

Foid

mon

zodi

orite

Foid

mon

zoga

bbro

AB-T

B-P

A P

F

B-P

AB-T



K-alkaline BP


Na-alkaline

3000

1000

Ankaratrite

Basanite

Alkali

basalt


Trachyandesite

Trachybasalt



Andesite-basalt

R2

SGN

N

200010000minus1000minus2000

Foidolite


2= 6Ca + Mg + Al





2O and Na








2





2



















2SiO4-KAlSiO

4[10 13 51] sug-






Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in



2





2



















2SiO4-KAlSiO

4[10 13 51] sug-






Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in





Mg 066 055 054 048ppm



Age (Ma) 1316


1198771

2037 1929 1758 17221198772

1789 1459 1561 1403120576Sr 670 012 1716 1412120576Nd 160 179 minus430 minus410













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in













2O




2O lt015 wt)














5 Geochemistry




Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in



Suite B-P



No of samples (4) (6) (4) (1) (1)Wt





Age 130 129 124 125 128 mdash


1198771







Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in





Mg 058 053 051 032 040ppm



Age 125 119 129 125 128


1198771

1215 954 749 545 6491198772






Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in





Mg 074 072 069 058 022ppm



Age 46 46 46 50 60


1198771

582 100 682 18 minus1567

1198772


120576Nd 267 291 223 257 154




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in




No of samples (5) (6) (3) (2) (1)Wt
























1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


















1000

100

10

1

01


H-TiL-Ti


1000

100

10

1

01


ASV sodic magmatism


1000

100

10

1

01




Phonolite

Beforsite

1000

100

10

1

01



Na-ASV

LK HK

1000

100

10

1

01




Trachyphonolite

Trachyte

1000

10

1


Ank

H-Ti

L-Ti

Parent magmas

Basanite

Alkali basalt



Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Mantle xenolithsDM

N-MORB

HIMU

120576t Nd

ASVsodic rocks

L-Ti

tholeiites


EM-II


PS

TS

ASVpotassic rocks



H-Ti tholeiites

10

6

2

minus2

minus6

minus10

minus14

minus18

minus22












DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


DMM

143N

d144N

d

0513

0512

0704 0706 0708

130 Ma

120572 120573

Veins

Veins

Types I II


Na

Tholeiites

K

Carbonatites

87Sr86Sr



minus18

minus20

minus22

minus24

minus26

minus28


PGA


ASV

PAR

PYL


Brazil

PR

AB

Parana Basin

Paraguay

ASV

Argen

tina

BoliviaAC

LP

AAB

Chile

PA

0100

200

300

400 600

500

16

20

24

28

32

70 65 60 55 50 45

Latitude S (deg)

(a)

0

100

200

300

400

500

600

700

800

900

1000

Dep

th (k

m)

70 65 60 55 50 45

120575VpVp ()


Longitude W (deg)

(b)














2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in










2O-CO



Acknowledgments




References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in



References
































































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


































































































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

research article magmatism in the asunción-sapucai...

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