Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India

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Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India. / Santosh, M.; He, Xiao-Fang; Waterton, Pedro; Szilas, Kristoffer; Pearson, D. Graham.

I: Lithos, Bind 376-377, 105772, 01.12.2020.

Publikation: Bidrag til tidsskriftTidsskriftartikelfagfællebedømt

Harvard

Santosh, M, He, X-F, Waterton, P, Szilas, K & Pearson, DG 2020, 'Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India', Lithos, bind 376-377, 105772. https://doi.org/10.1016/j.lithos.2020.105772

APA

Santosh, M., He, X-F., Waterton, P., Szilas, K., & Pearson, D. G. (2020). Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India. Lithos, 376-377, [105772]. https://doi.org/10.1016/j.lithos.2020.105772

Vancouver

Santosh M, He X-F, Waterton P, Szilas K, Pearson DG. Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India. Lithos. 2020 dec. 1;376-377. 105772. https://doi.org/10.1016/j.lithos.2020.105772

Author

Santosh, M. ; He, Xiao-Fang ; Waterton, Pedro ; Szilas, Kristoffer ; Pearson, D. Graham. / Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India. I: Lithos. 2020 ; Bind 376-377.

Bibtex

@article{aad1abe40f784193881e85cd1805950f,
title = "Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India",
abstract = "Chromite deposits hosted in a layered ultramafic-maficintrusion in the Archean Chithradurga greenstone belt are part of asuture that divides the Western and Central Dharwar craton blocks insouthern India. Serpentinised ultramafic rocks including dunite,peridotite, and phlogopite-rich clinopyroxenite occur with massivechromitite. The olivine compositions show two distinct groups, one withFo ~91-92 olivines, in the massive chromitite and another group witholivine Fo values of ~95-96, in the serpentinised dunite. The chromiteoccurs as massive chromitite and as an accessory phase in dunite. Theformer are characterized by high Cr# (Cr/(Cr+Al)×100=67-70) and moderateto high Mg# (Mg/(Mg+Fe)=52-66); The latter have a larger variation in Crwhich is likely related to sub-solidus re-equilibration of the chromiteduring the serpentinization event. In the massive chromitites, subsolidusre-equilibration of chromite is less significant or absent. Bulkrockmajor and trace element analyses of the peridotites reveal acomposition less magnesian than depleted mantle rocks, with low TiO2,Na2O, CaO and high Cr, Ni content, a general depletion in Sr andenrichment in Th, U. The chromitites contain varied PGE abundances (ΣPGE= 14-167 ppb) and IPGEs (Ir, Os, Ru) as well as enriched primitive-mantlenormalized PGE patterns (PdN/IrN= 0.004-0.241). These features suggestthe chromitites are cumulates formed from a highly magnesian parentalmagma with komatiitic affinity, derived by large degrees of partialmelting of a refractory mantle protolith, which underwent crustalcontamination. The Re-Os isotope data demonstrate a minimum Re-depletionmodel age (TRD) of 2895 ±24 Ma for the serpentinized dunite (MY11/3), anda more robust age of 3120 ±12 Ma for two chromitite samples, which weinterpret as the best estimate of the magmatic age of this ultramaficintrusion. Abundant zircon grains also occur within these ultramaficrocks with U-Pb ages spanning from ca. 2.9 Ga to ca. 2.4 Ga, with adominant age population in the range 2.8-2.6 Ga. We interpret the upperintercept age at ca. 2.9 Ga to represent the initial crystallization ofzircon in the ultramafic rocks, potentially as a result of meltinfiltration and metasomatism associated with regional granitoid crustformation and related metasomatic activity. The 2.5-2.4 Ga zircon agesreflect a late-stage high-grade metamorphic overprint.",
keywords = "Faculty of Science, Archean chromitite, Ultramafic intrusion, Platinum-group elements, Western Dharwar Craton, Chithradurga greenstone belt",
author = "M. Santosh and Xiao-Fang He and Pedro Waterton and Kristoffer Szilas and Pearson, {D. Graham}",
year = "2020",
month = dec,
day = "1",
doi = "10.1016/j.lithos.2020.105772",
language = "English",
volume = "376-377",
journal = "Lithos",
issn = "0024-4937",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Chromitites from an Archean layered intrusion in the Western Dharwar Craton, southern India

AU - Santosh, M.

AU - He, Xiao-Fang

AU - Waterton, Pedro

AU - Szilas, Kristoffer

AU - Pearson, D. Graham

PY - 2020/12/1

Y1 - 2020/12/1

N2 - Chromite deposits hosted in a layered ultramafic-maficintrusion in the Archean Chithradurga greenstone belt are part of asuture that divides the Western and Central Dharwar craton blocks insouthern India. Serpentinised ultramafic rocks including dunite,peridotite, and phlogopite-rich clinopyroxenite occur with massivechromitite. The olivine compositions show two distinct groups, one withFo ~91-92 olivines, in the massive chromitite and another group witholivine Fo values of ~95-96, in the serpentinised dunite. The chromiteoccurs as massive chromitite and as an accessory phase in dunite. Theformer are characterized by high Cr# (Cr/(Cr+Al)×100=67-70) and moderateto high Mg# (Mg/(Mg+Fe)=52-66); The latter have a larger variation in Crwhich is likely related to sub-solidus re-equilibration of the chromiteduring the serpentinization event. In the massive chromitites, subsolidusre-equilibration of chromite is less significant or absent. Bulkrockmajor and trace element analyses of the peridotites reveal acomposition less magnesian than depleted mantle rocks, with low TiO2,Na2O, CaO and high Cr, Ni content, a general depletion in Sr andenrichment in Th, U. The chromitites contain varied PGE abundances (ΣPGE= 14-167 ppb) and IPGEs (Ir, Os, Ru) as well as enriched primitive-mantlenormalized PGE patterns (PdN/IrN= 0.004-0.241). These features suggestthe chromitites are cumulates formed from a highly magnesian parentalmagma with komatiitic affinity, derived by large degrees of partialmelting of a refractory mantle protolith, which underwent crustalcontamination. The Re-Os isotope data demonstrate a minimum Re-depletionmodel age (TRD) of 2895 ±24 Ma for the serpentinized dunite (MY11/3), anda more robust age of 3120 ±12 Ma for two chromitite samples, which weinterpret as the best estimate of the magmatic age of this ultramaficintrusion. Abundant zircon grains also occur within these ultramaficrocks with U-Pb ages spanning from ca. 2.9 Ga to ca. 2.4 Ga, with adominant age population in the range 2.8-2.6 Ga. We interpret the upperintercept age at ca. 2.9 Ga to represent the initial crystallization ofzircon in the ultramafic rocks, potentially as a result of meltinfiltration and metasomatism associated with regional granitoid crustformation and related metasomatic activity. The 2.5-2.4 Ga zircon agesreflect a late-stage high-grade metamorphic overprint.

AB - Chromite deposits hosted in a layered ultramafic-maficintrusion in the Archean Chithradurga greenstone belt are part of asuture that divides the Western and Central Dharwar craton blocks insouthern India. Serpentinised ultramafic rocks including dunite,peridotite, and phlogopite-rich clinopyroxenite occur with massivechromitite. The olivine compositions show two distinct groups, one withFo ~91-92 olivines, in the massive chromitite and another group witholivine Fo values of ~95-96, in the serpentinised dunite. The chromiteoccurs as massive chromitite and as an accessory phase in dunite. Theformer are characterized by high Cr# (Cr/(Cr+Al)×100=67-70) and moderateto high Mg# (Mg/(Mg+Fe)=52-66); The latter have a larger variation in Crwhich is likely related to sub-solidus re-equilibration of the chromiteduring the serpentinization event. In the massive chromitites, subsolidusre-equilibration of chromite is less significant or absent. Bulkrockmajor and trace element analyses of the peridotites reveal acomposition less magnesian than depleted mantle rocks, with low TiO2,Na2O, CaO and high Cr, Ni content, a general depletion in Sr andenrichment in Th, U. The chromitites contain varied PGE abundances (ΣPGE= 14-167 ppb) and IPGEs (Ir, Os, Ru) as well as enriched primitive-mantlenormalized PGE patterns (PdN/IrN= 0.004-0.241). These features suggestthe chromitites are cumulates formed from a highly magnesian parentalmagma with komatiitic affinity, derived by large degrees of partialmelting of a refractory mantle protolith, which underwent crustalcontamination. The Re-Os isotope data demonstrate a minimum Re-depletionmodel age (TRD) of 2895 ±24 Ma for the serpentinized dunite (MY11/3), anda more robust age of 3120 ±12 Ma for two chromitite samples, which weinterpret as the best estimate of the magmatic age of this ultramaficintrusion. Abundant zircon grains also occur within these ultramaficrocks with U-Pb ages spanning from ca. 2.9 Ga to ca. 2.4 Ga, with adominant age population in the range 2.8-2.6 Ga. We interpret the upperintercept age at ca. 2.9 Ga to represent the initial crystallization ofzircon in the ultramafic rocks, potentially as a result of meltinfiltration and metasomatism associated with regional granitoid crustformation and related metasomatic activity. The 2.5-2.4 Ga zircon agesreflect a late-stage high-grade metamorphic overprint.

KW - Faculty of Science

KW - Archean chromitite

KW - Ultramafic intrusion

KW - Platinum-group elements

KW - Western Dharwar Craton

KW - Chithradurga greenstone belt

U2 - 10.1016/j.lithos.2020.105772

DO - 10.1016/j.lithos.2020.105772

M3 - Journal article

VL - 376-377

JO - Lithos

JF - Lithos

SN - 0024-4937

M1 - 105772

ER -

ID: 248146219