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New Rb-Sr isotopic ages and geochemistry of granitic gneisses from southern Bastar: implications for crustal evolution

Journal Article:

Abstract

Deformed gneisses from the southern Bastar craton yield Rb-Sr whole-rock ages of 2560 Ma and 2659 Ma with initial Sr ratios ranging between 0.70899 and 0.70726 respectively. The isotopic data are found to be scattered even at the outcrop scale which possibly indicate large-scale reworking of the gneisses during the period. The high initial Sr ratios that associate with scattering of the isotopic data reflect reworking of older gneisses. Geochemically, these gneisses are considered to be derived from an amphibolitic or basaltic protolith. The 2095 Ma (initial Sr ratio of 0.74312) old leucocratic granite intrusive into these gneisses represent early Proterozoic magmatic activity. Based on the available isotopic and geochemical data, it is suggested that the Bastar craton represents a polyphase, multicomponent terrain developed by repeated magmatism at a much earlier, probably during mid-Archaean, time and was extensively reworked during the time span between end-Archaean and early Proterozoic period. This reworking may be synchronous with coalescing of smaller crustal components possibly during the end-Archaean time. (author). 21 refs., 5 figs., 2 tabs.
Authors:
Sarkar, G; Gupta, S N; Bishui, P K [1] 
  1. Geological Survey of India, Calcutta (India). Geochronology and Isotope Geology Division
Publication Date:
Jan 01, 1994
Product Type:
Journal Article
Reference Number:
SCA: 400101; 580000; PA: AIX-26:062366; EDB-95:124805; SN: 95001457545
Resource Relation:
Journal Name: Indian Minerals; Journal Volume: 48; Journal Issue: 1-2; Other Information: PBD: Jan-Jun 1994
Subject:
40 CHEMISTRY; 58 GEOSCIENCES; GRANITES; ISOTOPE DATING; ABSORPTION SPECTROSCOPY; GEOCHEMISTRY; GNEISSES; ISOTOPE RATIO; PETROGRAPHY; RUBIDIUM 87; STRONTIUM 86; X-RAY FLUORESCENCE ANALYSIS
OSTI ID:
100061
Country of Origin:
India
Language:
English
Other Identifying Numbers:
Journal ID: INMIAR; ISSN 0019-5936; TRN: IN9501049062366
Submitting Site:
INIS
Size:
pp. 7-12
Announcement Date:
Oct 02, 1995

Journal Article:

Citation Formats

Sarkar, G, Gupta, S N, and Bishui, P K. New Rb-Sr isotopic ages and geochemistry of granitic gneisses from southern Bastar: implications for crustal evolution. India: N. p., 1994. Web.
Sarkar, G, Gupta, S N, & Bishui, P K. New Rb-Sr isotopic ages and geochemistry of granitic gneisses from southern Bastar: implications for crustal evolution. India.
Sarkar, G, Gupta, S N, and Bishui, P K. 1994. "New Rb-Sr isotopic ages and geochemistry of granitic gneisses from southern Bastar: implications for crustal evolution." India.
@misc{etde_100061,
title = {New Rb-Sr isotopic ages and geochemistry of granitic gneisses from southern Bastar: implications for crustal evolution}
author = {Sarkar, G, Gupta, S N, and Bishui, P K}
abstractNote = {Deformed gneisses from the southern Bastar craton yield Rb-Sr whole-rock ages of 2560 Ma and 2659 Ma with initial Sr ratios ranging between 0.70899 and 0.70726 respectively. The isotopic data are found to be scattered even at the outcrop scale which possibly indicate large-scale reworking of the gneisses during the period. The high initial Sr ratios that associate with scattering of the isotopic data reflect reworking of older gneisses. Geochemically, these gneisses are considered to be derived from an amphibolitic or basaltic protolith. The 2095 Ma (initial Sr ratio of 0.74312) old leucocratic granite intrusive into these gneisses represent early Proterozoic magmatic activity. Based on the available isotopic and geochemical data, it is suggested that the Bastar craton represents a polyphase, multicomponent terrain developed by repeated magmatism at a much earlier, probably during mid-Archaean, time and was extensively reworked during the time span between end-Archaean and early Proterozoic period. This reworking may be synchronous with coalescing of smaller crustal components possibly during the end-Archaean time. (author). 21 refs., 5 figs., 2 tabs.}
journal = {Indian Minerals}
issue = {1-2}
volume = {48}
journal type = {AC}
place = {India}
year = {1994}
month = {Jan}
}