skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study

Abstract

Charnockite formation in the Angul district of Orissa took place between 1088 + 26/ -17 Ma, the U-Pb zircon upper intercept crystallization age of a leptynite neosome, and 957 +8/ -4-956 {plus minus} 4 Ma, the U-Pb zircon-monazite upper intercept and U-Pb monazite crystallization ages of a granite. Confirmation of the Proterozoic age of the charnockites is given by (1) a U-Pb zircon upper intercept 1159 + 59/ -30 Ma age and a Rb-Sr whole-rock 1080 {plus minus} 65 Ma age for an augen gneiss which pre-dates the leptynite, and (2) U-Pb monazite ages of 973 {plus minus} 5,964 {plus minus} 4, and 953 {plus minus} 4 Ma for a gray quartzofeldspathic gneiss, the augen gneiss, and the leptynite, respectively: these late Proterozoic dates are interpreted as representing ages recorded during charnockitization. The ca. 950-980 Ma charnockite- and granite-forming events are related to the evolution of mantle-derived, CO{sub 2}-bearing basic magma emplaced into the deeper levels of an extensional tectonic-transcurrent fault regime. The ca. 1100-1150 Ma tectonothermal and igneous events represent compressional tectonism in reactivated crystalline basement in the late mid-Proterozoic Eastern Ghats orogenic belt.

Authors:
; ; ;  [1]
  1. (Scottish Universities Research and Reactor Centre, Glasgow (Scotland))
Publication Date:
OSTI Identifier:
7104132
Resource Type:
Journal Article
Journal Name:
Journal of Geology; (USA)
Additional Journal Information:
Journal Volume: 96:6; Journal ID: ISSN 0022-1376
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; GEOLOGIC DEPOSITS; AGE ESTIMATION; INDIA; CARBON DIOXIDE; CRYSTALLIZATION; GRANITES; ISOTOPE DATING; ISOTOPE RATIO; LEAD; MAGMA SYSTEMS; MONAZITES; RUBIDIUM; STRONTIUM; TECTONICS; URANIUM; ACTINIDE COMPOUNDS; ACTINIDES; ALKALI METALS; ALKALINE EARTH METALS; ASIA; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; DEVELOPING COUNTRIES; ELEMENTS; GEOTHERMAL SYSTEMS; IGNEOUS ROCKS; MATERIALS; METALS; MINERALS; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; PHOSPHATES; PHOSPHORUS COMPOUNDS; PLUTONIC ROCKS; RADIOACTIVE MATERIALS; RADIOACTIVE MINERALS; RARE EARTH COMPOUNDS; ROCKS; THORIUM COMPOUNDS; THORIUM MINERALS; THORIUM PHOSPHATES; 580000* - Geosciences

Citation Formats

Aftalion, M., Bowes, D.R., Dash, B., and Dempster, T.J. Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study. United States: N. p., 1988. Web. doi:10.1086/629269.
Aftalion, M., Bowes, D.R., Dash, B., & Dempster, T.J. Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study. United States. doi:10.1086/629269.
Aftalion, M., Bowes, D.R., Dash, B., and Dempster, T.J. Tue . "Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study". United States. doi:10.1086/629269.
@article{osti_7104132,
title = {Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study},
author = {Aftalion, M. and Bowes, D.R. and Dash, B. and Dempster, T.J.},
abstractNote = {Charnockite formation in the Angul district of Orissa took place between 1088 + 26/ -17 Ma, the U-Pb zircon upper intercept crystallization age of a leptynite neosome, and 957 +8/ -4-956 {plus minus} 4 Ma, the U-Pb zircon-monazite upper intercept and U-Pb monazite crystallization ages of a granite. Confirmation of the Proterozoic age of the charnockites is given by (1) a U-Pb zircon upper intercept 1159 + 59/ -30 Ma age and a Rb-Sr whole-rock 1080 {plus minus} 65 Ma age for an augen gneiss which pre-dates the leptynite, and (2) U-Pb monazite ages of 973 {plus minus} 5,964 {plus minus} 4, and 953 {plus minus} 4 Ma for a gray quartzofeldspathic gneiss, the augen gneiss, and the leptynite, respectively: these late Proterozoic dates are interpreted as representing ages recorded during charnockitization. The ca. 950-980 Ma charnockite- and granite-forming events are related to the evolution of mantle-derived, CO{sub 2}-bearing basic magma emplaced into the deeper levels of an extensional tectonic-transcurrent fault regime. The ca. 1100-1150 Ma tectonothermal and igneous events represent compressional tectonism in reactivated crystalline basement in the late mid-Proterozoic Eastern Ghats orogenic belt.},
doi = {10.1086/629269},
journal = {Journal of Geology; (USA)},
issn = {0022-1376},
number = ,
volume = 96:6,
place = {United States},
year = {1988},
month = {11}
}