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Title: Sm-Nd isotopic data from Archean metavolcanic rocks at Holenarsipur, South India

Abstract

Results of a Sm-Nd isotopic analysis of Archean metavolcanics in the Holenarsipur greenstone belt, Karnataka, South India, give a whole-rock isochron age of 2.62 Ga for lightly deformed metabasaltic amphibolites in the northern part of the belt. This is within error of the age of high-grade metamorphism and crustal thickening which affected areas further to the south during the late Archean. Together with the geochemical affinities of these and other metavolcanics in Karnataka, and results of regional structural analysis, this unexpected age supports a model relating volcanism and crustal thickening to northward subduction and crustal accretion during the late Archean. Data from basic and ultrabasic metavolcanics from the more strongly deformed and higher-grade southern arm of the Holenarsipur belt do not permit an age greater than 3.0 Ga. Previously, these rocks were regarded as part of an older supracrustal sequence that predated the local 3.0 to 3.3 Ga gneissic complex. The new dates therefore considerably simplify attempts at accounting for greenstone evolution in South India.

Authors:
; ;
Publication Date:
Research Org.:
Open Univ., Milton Keynes, England
OSTI Identifier:
5516374
Resource Type:
Journal Article
Journal Name:
J. Geol.; (United States)
Additional Journal Information:
Journal Volume: 95:6
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; GEOLOGIC DEPOSITS; AGE ESTIMATION; INDIA; CONTINENTAL CRUST; GEOLOGIC HISTORY; GEOLOGIC MODELS; ISOTOPE DATING; METAMORPHISM; NEODYMIUM ISOTOPES; SAMARIUM ISOTOPES; THICKNESS; VOLCANIC ROCKS; VOLCANISM; ASIA; DEVELOPING COUNTRIES; DIMENSIONS; EARTH CRUST; IGNEOUS ROCKS; ISOTOPES; RARE EARTH ISOTOPES; ROCKS; 580100* - Geology & Hydrology- (-1989)

Citation Formats

Drury, S.A., Van Calsteren, P.C., and Reeves-Smith, G.J. Sm-Nd isotopic data from Archean metavolcanic rocks at Holenarsipur, South India. United States: N. p., 1987. Web. doi:10.1086/629182.
Drury, S.A., Van Calsteren, P.C., & Reeves-Smith, G.J. Sm-Nd isotopic data from Archean metavolcanic rocks at Holenarsipur, South India. United States. doi:10.1086/629182.
Drury, S.A., Van Calsteren, P.C., and Reeves-Smith, G.J. Sun . "Sm-Nd isotopic data from Archean metavolcanic rocks at Holenarsipur, South India". United States. doi:10.1086/629182.
@article{osti_5516374,
title = {Sm-Nd isotopic data from Archean metavolcanic rocks at Holenarsipur, South India},
author = {Drury, S.A. and Van Calsteren, P.C. and Reeves-Smith, G.J.},
abstractNote = {Results of a Sm-Nd isotopic analysis of Archean metavolcanics in the Holenarsipur greenstone belt, Karnataka, South India, give a whole-rock isochron age of 2.62 Ga for lightly deformed metabasaltic amphibolites in the northern part of the belt. This is within error of the age of high-grade metamorphism and crustal thickening which affected areas further to the south during the late Archean. Together with the geochemical affinities of these and other metavolcanics in Karnataka, and results of regional structural analysis, this unexpected age supports a model relating volcanism and crustal thickening to northward subduction and crustal accretion during the late Archean. Data from basic and ultrabasic metavolcanics from the more strongly deformed and higher-grade southern arm of the Holenarsipur belt do not permit an age greater than 3.0 Ga. Previously, these rocks were regarded as part of an older supracrustal sequence that predated the local 3.0 to 3.3 Ga gneissic complex. The new dates therefore considerably simplify attempts at accounting for greenstone evolution in South India.},
doi = {10.1086/629182},
journal = {J. Geol.; (United States)},
number = ,
volume = 95:6,
place = {United States},
year = {1987},
month = {11}
}