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Zircon U–Pb SHRIMP and monazite EPMA U–Th–total Pb geochronology of granulites of the western boundary, Eastern Ghats Belt, India: a new possibility for Neoproterozoic exhumation history

By
A. Chatterjee
A. Chatterjee
1
Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, Japan
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K. Das
K. Das
1
Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, Japan
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S. Bose
S. Bose
2
Department of Geology, Presidency University, 86/1 College Street, Kolkata 700073, India
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P. Ganguly
P. Ganguly
2
Department of Geology, Presidency University, 86/1 College Street, Kolkata 700073, India
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H. Hidaka
H. Hidaka
3
Department of Earth and Planetary Systems Science, Nagoya University, Nagoya 464-8601, Aichi, Japan
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Published:
January 01, 2017

Abstract

We present detailed and high-precision geochronological data on granulites occurring along the western boundary of the Eastern Ghats Belt, India. Age data on systematically sampled rocks coupled with geochemical observation have a potential to unravel the overprinted tectonothermal events operated during Precambrian time. Zircon U–Pb SHRIMP and monazite electron probe microanalysis (EPMA) U–Th–total Pb analyses, chemical zoning, microtextural investigation, and pressure–temperature calculations were carried out on samples of four different rock types. Inherited zircons from migmatitic quartzofeldspathic gneiss and mafic granulite yielded ages of approximately 2900–2350 Ma, representing an older crustal component. The age of granulite metamorphism recorded from charnockite and pelitic granulite ranges between approximately 950 and 930 Ma (from zircon and monazite). A possible decompression event from this area that occurred during Rodinia break-up is recorded from the Y-rich zones of monazite closely associated with porphyroblastic garnet in pelitic granulite and dates from approximately 800 to 750 Ma. Zircon grains of charnockite also yield a similar age. The youngest age of approximately 525–510 Ma documented from the monazite grains of migmatitic quartzofeldspathic gneiss and pelitic granulite, along with a spot age from zircon of migmatitic quartzofeldspathic gneiss, testifies to the final assembly of East Antarctica with cratonic India as a part of East Gondwana.

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Geological Society, London, Special Publications

Crustal Evolution of India and Antarctica: The Supercontinent Connection

N. C. Pant
N. C. Pant
University of Delhi, India
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S. Dasgupta
S. Dasgupta
Jamia Millia Islamia, India
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Geological Society of London
Volume
457
ISBN electronic:
9781786203380
Publication date:
January 01, 2017

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