Isotopic composition of two Precambrian stratiform barite deposits from the Indian shield

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(91)90419-6· OSTI ID:6053502

Deb, M ^[1]; Hoefs, J ^[2]; Baumann, A ^[3]

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1. Delhi Univ. (India)
2. Geochemisches Institut der Universitaet, Goettingen (West Germany)
3. Westfalische Wilhelms-Universitaet, Muenster (West Germany)

Stratiform barite beds, interlayered with (fuchsite) quartzites and mafic metavolcanics and containing minor disseminations of sulfides, occur in the Archaean (>3.3 Ga) Sargur Group of rocks at Ghattihosahalli, in the state of Karnataka, south India, and near Jagat, within quartzites and metamorphosed flood basalts underlying the middle Proterozoic ({approximately}2.0 Ga) Aravalli Supergroup in the state of Rajasthan, northwest India. The Sargur barites have {delta}{sup 34}S in the range of 4.02 to 7.45{per thousand}. Disseminations of detrital pyrite, occurring in layers in the barite have {delta}{sup 34}S between {minus}3.62 and {minus}5.87{per thousand}. These barites are also characterized by low {sup 87}Sr/{sup 86}Sr ratios. The basal Aravalli barites, in contrast, have exceptionally high {sup 87}Sr/{sup 86}Sr ratios and {delta}{sup 34}S between 17.11 and 21.4{per thousand}. {delta}{sup 34}S in disseminated chalcopyrite within banded barite-amphibolite samples from the same occurrence varies between 6.21 and 8.52{per thousand}. The isotopic data of the Sargur barites most probably reflect Archean coeval seawater composition. The mantle-like values indicate buffering of the seawater by mantle-derived basaltic crust. In contrast, the Aravalli barites bear the signature of a Proterozoic sea whose sulfur isotope composition is closer to that of present-day oceans. The unusually high {sup 87}Sr/{sup 86}Sr ratios point, however, to a local, highly radiogenic source, which had affected the Sr isotopic composition of coeval, normal seawater.

• OSTI ID: 6053502
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 55:1; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
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BARITE
BARIUM COMPOUNDS
BARIUM SULFATES
BASALT
BETA DECAY RADIOISOTOPES
CHALCOGENIDES
CHEMISTRY
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ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
INDIA
INTERMEDIATE MASS NUCLEI
IRON COMPOUNDS
IRON SULFIDES
ISOMERIC TRANSITION ISOTOPES
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
METAMORPHIC ROCKS
MINERALIZATION
MINERALS
NUCLEI
OXYGEN COMPOUNDS
PRECAMBRIAN ERA
PYRITE
QUARTZITES
RADIOISOTOPES
ROCKS
SEAWATER
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STRONTIUM 86
STRONTIUM 87
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SULFATE MINERALS
SULFATES
SULFIDE MINERALS
SULFIDES
SULFUR 34
SULFUR COMPOUNDS
SULFUR ISOTOPES
TRANSITION ELEMENT COMPOUNDS
VOLCANIC ROCKS
WATER