-
Worked Example of Batch Melting: Rb and SrBasalt with the mode:
1. Convert to weight % minerals (Wol Wcpx etc.)
Table 9.2. Conversion from mode toweight percent
Mineral Mode Density Wt prop Wt%ol 15 3.6 54 0.18cpx 33 3.4 112.2 0.37plag 51 2.7 137.7 0.45
Sum 303.9 1.00
-
Worked Example of Batch Melting: Rb and Sr
Table 9.2. Conversion from mode toweight percent
Mineral Mode Density Wt prop Wt%ol 15 3.6 54 0.18cpx 33 3.4 112.2 0.37plag 51 2.7 137.7 0.45
Sum 303.9 1.00
Basalt with the mode:
1. Convert to weight % minerals (Wol Wcpx etc.)
2. Use equation eq. 9.4: Di = Σ WA Diand the table of D values for Rb and Sr in each mineral to calculate the bulk distribution coefficients: DRb = 0.045 and DSr = 0.848
-
Table 9.3 . Batch Fractionation Model for Rb and Sr
CL/CO = 1/(D(1-F)+F)DRb DSr
F 0.045 0.848 Rb/Sr0.05 9.35 1.14 8.190.1 6.49 1.13 5.730.15 4.98 1.12 4.430.2 4.03 1.12 3.610.3 2.92 1.10 2.660.4 2.29 1.08 2.110.5 1.89 1.07 1.760.6 1.60 1.05 1.520.7 1.39 1.04 1.340.8 1.23 1.03 1.200.9 1.10 1.01 1.09
3. Use the batch melting equation
(9.5)
to calculate CL/CO for various values of F
From Winter (2010) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
CC
1Di(1 F) F
L
O=
− +
-
4. Plot CL/CO vs. F for each element
Figure 9.3. Change in the concentration of Rb and Sr in the melt derived by progressive batch melting of a basaltic rock consisting of plagioclase, augite, and olivine. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Incremental Batch Melting
Calculate batch melting for successive batches (same equation)
Must recalculate Di as solids change as minerals are selectively melted (computer)
-
Fractional Crystallization1. Crystals remain in equilibrium with each
melt increment
CC
1Di(1 F) F
L
O=
− +
-
Rayleigh fractionationThe other extreme: separation of each crystal as it formed = perfectly continuous fractional crystallization in a magma chamber
-
Rayleigh fractionationThe other extreme: separation of each crystal as it formed = perfectly continuous fractional crystallization in a magma chamber Concentration of some element in the residual
liquid, CL is modeled by the Rayleigh equation:eq. 9.8 CL/CO = F (D -1) Rayleigh Fractionation
-
4. Plot CL/CO vs. F for each element
Figure 9.3. Change in the concentration of Rb and Sr in the melt derived by progressive batch melting of a basaltic rock consisting of plagioclase, augite, and olivine. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Other models are used to analyze Mixing of magmas Wall-rock assimilation Zone refining Combinations of processes
-
The Rare Earth Elements (REE)
-
Contrasts and similarities in the D values:All are incompatible
Also Note:
HREE are less incompatible
Especially in garnet
Eu can → 2+ which conc. in plagioclase
Table 9-1. Partition Coefficients (CS/CL) for Some Commonly Used Trace Elements in Basaltic and Andesitic Rocks
Olivine Opx Cpx Garnet Plag Amph MagnetiteRb 0.01 0.022 0.031 0.042 0.071 0.29 Sr 0.014 0.04 0.06 0.012 1.83 0.46 Ba 0.01 0.013 0.026 0.023 0.23 0.42 Ni 14.0 5.0 7.0 0.955 0.01 6.8 29.Cr 0.7 10.0 34.0 1.345 0.01 2.0 7.4La 0.007 0.03 0.056 0.001 0.148 0.544 2.Ce 0.006 0.02 0.092 0.007 0.082 0.843 2.Nd 0.006 0.03 0.23 0.026 0.055 1.34 2.Sm 0.007 0.05 0.445 0.102 0.039 1.804 1.Eu 0.007 0.05 0.474 0.243 0.1/1.5* 1.557 1.Dy 0.013 0.15 0.582 3.17 0.023 2.024 1.Er 0.026 0.23 0.583 6.56 0.02 1.74 1.5Yb 0.049 0.34 0.542 11.5 0.023 1.642 1.4Lu 0.045 0.42 0.506 11.9 0.019 1.563Data from Rollinson (1993). * Eu3+/Eu2+ Italics are estimated
Rar
e Ea
rth E
lem
ents
-
REE DiagramsPlots of concentration as the ordinate (y-axis)
against increasing atomic number Degree of compatibility increases from left to right
across the diagram (“lanthanide contraction”)
Con
cent
ratio
n
La Ce Nd Sm Eu Tb Er Dy Yb Lu
-
-3
-2
-10
1
2
34
5
6
7
89
10
11
0 10 20 30 40 50 60 70 80 90 100
Atomic Number (Z)
Log
(Abu
ndan
ce in
CI C
hond
ritic
Met
eorit
e) HHe
Li
Be
B
C
N
O
FSc
FeNi
Ne MgSiS
CaAr
Ti
PbPtSn BaV
K
NaAlP
Cl
ThU
Eliminate Oddo-Harkins effect and make y-scale more functional by normalizing to a standard estimates of primordial mantle REE chondrite meteorite concentrations
Chart2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
90
92
H
He
Li
Be
B
C
N
O
F
Sc
Fe
Ni
Ne
Mg
Si
S
Ca
Ar
Ti
Pb
Pt
Sn
Ba
V
K
Na
Al
P
Cl
Th
U
Atomic Number (Z)
Log (Abundance in CI Chondritic Meteorite)
10.4456042033
9.434568904
1.7566361082
-0.1366771399
1.3263358609
7.0043213738
6.4955443375
7.3765769571
2.9258275746
6.5365584426
4.7589118924
6.0310042814
4.9289076902
6
4.0170333393
5.711807229
3.719331287
5.0043213738
3.5763413502
4.7860412102
1.5340261061
3.3802112417
2.4668676204
4.1303337685
3.9800033716
5.9542425094
3.3521825181
4.6928469193
2.717670503
3.1003705451
1.5774917998
2.0755469614
0.8169038394
1.7930916002
1.0718820073
1.6532125138
0.8506462352
1.3710678623
0.6665179806
1.0569048513
-0.1561445774
0.4065401804
0.2695129442
-0.4634415574
0.1430148003
-0.3133637307
0.206825876
-0.735182177
0.5820633629
-0.5100415206
0.6821450764
-0.0457574906
0.6720978579
-0.4294570601
0.652246341
-0.3506651413
0.0553783314
-0.7775436633
-0.0820221174
-0.5880437621
-1.0118871597
-0.4814860601
-1.2196826879
-0.4042833801
-1.051098239
-0.6006724678
-1.4225082002
-0.6057234732
-1.4353339357
-0.8124792792
-1.6840296545
-0.876148359
-1.2865094569
-0.1706962272
-0.1797985405
0.1271047984
-0.7281583935
-0.468521083
-0.735182177
0.4983105538
-0.8416375079
-1.474955193
-2.0457574906
Sheet1
at nosymbolmeteors/msolar
1H10.44560420332.79E+101.0027900000000
2He9.4345689042.72E+091.002720000000
3Li1.756636108257.10.3520.0108761329
4Be-0.13667713990.730.810.5911971831
5B1.326335860921.20.9019.1388888889
6C7.00432137381.01E+071.0010100000
7N6.49554433753.13E+061.003130000
8O7.37657695712.38E+071.0023800000
9F2.92582757468431.02858.0535714286
10Ne6.53655844263.44E+061.003440000
11Na4.75891189245.74E+041.0057581.9334389857
12Mg6.03100428141.07E+061.001074000
13Al4.92890769028.49E+041.0084768.9814814815
14Si61.00E+061.001000000
15P4.01703333931.04E+040.9810175.9425493716
16S5.7118072295.15E+050.99510749.656121045
17Cl3.71933128752401.045468.6907020873
18Ar5.00432137381.01E+051.00101000
19K3.576341350237701.003762.6510721248
20Ca4.78604121026.11E+041.0061292.7444794953
21Sc1.534026106134.21.0034.3106796117
22Ti3.380211241724001.012429.2089249493
23V2.46686762042931.00291.5422885572
24Cr4.13033376851.35E+041.0013476.2323943662
25Mn3.980003371695500.979308.2278481013
26Fe5.95424250949.00E+051.02919174.434087883
27Co3.352182518122501.002254.5824847251
28Ni4.69284691934.93E+041.0049300
29Cu2.7176705035220.99514.6651053864
30Mn3.100370545112600.991246.4516129032
31Ga1.577491799837.80.9234.7808306709
32Ge2.07554696141190.94111.7878787879
33As0.81690383946.56
34Se1.793091600262.1
35Br1.071882007311.8
36Kr1.653212513845
37Rb0.85064623527.091.087.6808333333
38Sr1.371067862323.50.9923.2593856655
39Y0.66651798064.641.014.6818018018
40Zr1.056904851311.41.0011.3563218391
41Nb-0.15614457740.6981.010.7079714286
42Mo0.40654018042.550.982.4979591837
44Ru0.26951294421.861.011.8804395604
45Rh-0.46344155740.3441.030.3534678899
46Pd0.14301480031.390.991.3818235294
47Ag-0.31336373070.4860.760.3684193548
48Cd0.2068258761.611.061.7014772727
49In-0.7351821770.1842.020.3724878049
50Sn0.58206336293.820.933.5700934579
51Sb-0.51004152060.3090.960.2971153846
52Te0.68214507644.81
53I-0.04575749060.9
54Xe0.67209785794.7
55Cs-0.42945706010.372
56Ba0.6522463414.490.964.3274660633
57La-0.35066514130.4461.020.4534333333
58Ce0.05537833141.1360.961.0936645963
59Pr-0.77754366330.16690.910.1519217949
60Nd-0.08202211740.82791.020.8447959184
62Sm-0.58804376210.25821.030.266185567
63Eu-1.01188715970.09730.940.0918944444
64Gd-0.48148606010.331.050.3454205607
65Tb-1.21968268790.06030.300.0182727273
66Dy-0.40428338010.39420.960.3770608696
67Ho-1.0510982390.08890.520.046228
68Er-0.60067246780.25080.980.24552
69Tm-1.42250820020.03780.040.0014538462
70Yb-0.60572347320.24791.140.2818231579
71Lu-1.43533393570.03676.330.2324333333
72Hf-0.81247927920.1541.210.1856438356
73Ta-1.68402965450.0207
74W-0.8761483590.1331.630.2171029412
75Re-1.28650945690.0517
76Os-0.17069622720.6751.050.7092391304
77Ir-0.17979854050.6610.990.651350365
78Pt0.12710479841.341.071.4357142857
79Au-0.72815839350.1871.220.2275542169
80Hg-0.4685210830.34
81Tl-0.7351821770.1841.100.2019512195
82Pb0.49831055383.150.902.8426829268
83Bi-0.84163750790.144
90Th-1.4749551930.03351.500.05025
92U-2.04575749060.009
CI chondrite from Anders and Grevesse
&A
Page &P
Sheet1
&A
Page &P
Atomic Number
Ratio solar/chondrite
&A
Page &P
CI Chondrite
solar system
&A
Page &P
H
He
Li
Be
B
C
N
O
F
Sc
Fe
Ni
Ne
Mg
Si
S
Ca
Ar
Ti
Pb
Pt
Sn
Ba
V
K
Na
Al
P
Cl
Th
U
Atomic Number (Z)
Log (Abundance in CI Chondritic Meteorite)
-
What would an REE diagram look like for an analysis of a chondrite
meteorite?
0.00
2.00
4.00
6.00
8.00
10.00
56 58 60 62 64 66 68 70 72
sam
ple/
chon
drite
LLa Ce Nd Sm Eu Tb Er Yb Lu
?
-
Divide each element in analysis by the concentration in a chondrite standard
0.00
2.00
4.00
6.00
8.00
10.00
56 58 60 62 64 66 68 70 72
sam
ple/
chon
drite
LLa Ce Nd Sm Eu Tb Er Yb Lu
-
REE diagrams using batch melting model of a garnet lherzolite for various values of F:
Figure 9.4. Rare Earth concentrations (normalized to chondrite) for melts produced at various values of F via melting of a hypothetical garnet lherzolite using the batch melting model (equation 9.5). From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Europium anomaly when plagioclase is a fractionating phenocryst
or a residual solid in source
Figure 9.5. REE diagram for 10% batch melting of a hypothetical lherzolite with 20% plagioclase, resulting in a pronounced negative Europium anomaly. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Normalized Multielement (Spider) DiagramsAn extension of the normalized REE technique to a broader spectrum of elements
Fig. 9.6. Spider diagram for an alkaline basalt from Gough Island, southern Atlantic. After Sun and MacDonough (1989). In A. D. Saunders and M. J. Norry (eds.), Magmatism in the Ocean Basins. Geol. Soc. London Spec. Publ., 42. pp. 313-345.
Chondrite-normalized spider diagrams are commonly organized by (the author’s estimate) of increasing incompatibility L ← R
Different estimates →different ordering (poor standardization)
-
MORB-normalized Spider Separates LIL and HFS
Figure 9.7. Ocean island basalt plotted on a mid-ocean ridge basalt (MORB) normalized spider diagram of the type used by Pearce (1983). Data from Sun and McDonough (1989). From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Application of Trace Elements to Igneous Systems
1. Use like major elements on variation diagrams to document FX, assimilation, etc. in a suite of rocks More sensitive → larger variations as process
continues
Figure 9.1a. Ni Harker Diagram for Crater Lake. From data compiled by Rick Conrey. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Contrasts and similarities in the D values:All are incompatible
Also Note:
HREE are less incompatible
Especially in garnet
Eu can → 2+ which conc. in plagioclase
Table 9-1. Partition Coefficients (CS/CL) for Some Commonly Used Trace Elements in Basaltic and Andesitic Rocks
Olivine Opx Cpx Garnet Plag Amph MagnetiteRb 0.01 0.022 0.031 0.042 0.071 0.29 Sr 0.014 0.04 0.06 0.012 1.83 0.46 Ba 0.01 0.013 0.026 0.023 0.23 0.42 Ni 14.0 5.0 7.0 0.955 0.01 6.8 29.Cr 0.7 10.0 34.0 1.345 0.01 2.0 7.4La 0.007 0.03 0.056 0.001 0.148 0.544 2.Ce 0.006 0.02 0.092 0.007 0.082 0.843 2.Nd 0.006 0.03 0.23 0.026 0.055 1.34 2.Sm 0.007 0.05 0.445 0.102 0.039 1.804 1.Eu 0.007 0.05 0.474 0.243 0.1/1.5* 1.557 1.Dy 0.013 0.15 0.582 3.17 0.023 2.024 1.Er 0.026 0.23 0.583 6.56 0.02 1.74 1.5Yb 0.049 0.34 0.542 11.5 0.023 1.642 1.4Lu 0.045 0.42 0.506 11.9 0.019 1.563Data from Rollinson (1993). * Eu3+/Eu2+ Italics are estimated
Rar
e Ea
rth E
lem
ents
-
2. Identification of the source rock or a particular mineral involved in either partial melting or fractional crystallization processes
-
Table 9-1. Partition Coefficients (CS/CL) for Some Commonly Used Trace Elements in Basaltic and Andesitic Rocks
Olivine Opx Cpx Garnet Plag Amph MagnetiteRb 0.01 0.022 0.031 0.042 0.071 0.29 Sr 0.014 0.04 0.06 0.012 1.83 0.46 Ba 0.01 0.013 0.026 0.023 0.23 0.42 Ni 14.0 5.0 7.0 0.955 0.01 6.8 29.Cr 0.7 10.0 34.0 1.345 0.01 2.0 7.4La 0.007 0.03 0.056 0.001 0.148 0.544 2.Ce 0.006 0.02 0.092 0.007 0.082 0.843 2.Nd 0.006 0.03 0.23 0.026 0.055 1.34 2.Sm 0.007 0.05 0.445 0.102 0.039 1.804 1.Eu 0.007 0.05 0.474 0.243 0.1/1.5* 1.557 1.Dy 0.013 0.15 0.582 3.17 0.023 2.024 1.Er 0.026 0.23 0.583 6.56 0.02 1.74 1.5Yb 0.049 0.34 0.542 11.5 0.023 1.642 1.4Lu 0.045 0.42 0.506 11.9 0.019 1.563Data from Rollinson (1993). * Eu3+/Eu2+ Italics are estimated
Rar
e Ea
rth E
lem
ents
Garnet concentrates the HREE and fractionates among them
Thus if garnet is in equilibrium with the partial melt (a residual phase in the source left behind) expect a steep (-) slope in REE and HREE
Shallow (< 40 km) partial melting of the mantle will have plagioclase in the resuduum and a Eu anomaly will result
-
0.00
2.00
4.00
6.00
8.00
10.00
56 58 60 62 64 66 68 70 72
sam
ple/
chon
drite
La Ce Nd Sm Eu Tb Er Yb Lu
67% Ol 17% Opx 17% Cpx
0.00
2.00
4.00
6.00
8.00
10.00
56 58 60 62 64 66 68 70 72
sam
ple/
chon
drite
La Ce Nd Sm Eu Tb Er Yb Lu
57% Ol 14% Opx 14% Cpx 14% Grt
Garnet and Plagioclase effect on HREE
0.00
2.00
4.00
6.00
8.00
10.00
sam
ple/
chon
drite
60% Ol 15% Opx 15% Cpx 10%Plag
La Ce Nd Sm Eu Tb Er Yb Lu
-
Figure 9.3. Change in the concentration of Rb and Sr in the melt derived by progressive batch melting of a basaltic rock consisting of plagioclase, augite, and olivine. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
-
Element Use as a Petrogenetic Indicator
Ni, Co, Cr Highly compatible elements. Ni and Co are concentrated in olivine, and Cr in spinel and clinopyroxene. High concentrations
indicate a mantle source, limited fractionation, or crystal accumulation.
Zr, Hf Very incompatible elements that do not substitute into major silicate phases (although they may replace Ti in titanite or
rutile). High concentrations imply an enriched source or extensive liquid evolution.
Nb, Ta High field-strength elements that partition into Ti-rich phases (titanite, Ti-amphibole, Fe-Ti oxides. Typically low
concentrations in subduction-related melts.
Ru, Rh, Pd,
Re, Os, Ir,
Pd
Platinum group elements (PGEs) are siderophile and used mostly to study melting and crystallization in mafic-ultramafic
systems in which PGEs are typically hosted by sulfides. The Re/Os isotopic system is controlled by initial PGE
differentiation and is applied to mantle evolution and mafic melt processes.
Sc Concentrates in pyroxenes and may be used as an indicator of pyroxene fractionation.
Sr Substitutes for Ca in plagioclase (but not in pyroxene), and, to a lesser extent, for K in K-feldspar. Behaves as a compatible
element at low pressure where plagioclase forms early, but as an incompatible element at higher pressure where
plagioclase is no longer stable.
REE Myriad uses in modeling source characteristics and liquid evolution. Garnet accommodates the HREE more than the LREE,
and orthopyroxene and hornblende do so to a lesser degree. Titanite and plagioclase accommodates more LREE. Eu2+ is
strongly partitioned into plagioclase.
Y Commonly incompatible. Strongly partitioned into garnet and amphibole. Titanite and apatite also concentrate Y, so the
presence of these as accessories could have a significant effect.
Table 9.6 A Brief Summary of Some Particularly Useful Trace Elements in Igneous Petrology
-
Trace elements as a tool to determine paleotectonic environment
Useful for rocks in mobile belts that are no longer recognizably in their original setting
Can trace elements be discriminators of igneous environment?
Approach is empirical on modern occurrences Concentrate on elements that are immobile
during low/medium grade metamorphism
-
Figure 9.8 Examples of discrimination diagrams used to infer tectonic setting of ancient (meta)volcanics. (a) after Pearce and Cann (1973), (b) after Pearce (1982), Coish et al. (1986). Reprinted by permission of the American Journal of Science, (c) after Mullen (1983) Copyright © with permission from Elsevier Science, (d) and (e) after Vermeesch (2005) © AGU with permission.
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