TY - JOUR
T1 - Petrology and geochronology of a suite of pelitic granulites from parts of the Chotanagpur Granite Gneiss Complex, eastern India
T2 - Evidence for Stenian-Tonian reworking of a late Paleoproterozoic crust
AU - Dey, Anindita
AU - Karmakar, Shreya
AU - Ibanez-Mejia, Mauricio
AU - Mukherjee, Subham
AU - Sanyal, Sanjoy
AU - Sengupta, Pulak
N1 - Funding Information:
A. D. acknowledges the financial support from the Council of Scientific and Industrial Research (CSIR), New Delhi. S. K. and S. M. acknowledge the financial support from the University Grants Commission (UGC), New Delhi. P. S. and S. S. acknowledge the grants received from the following programmes awarded to the Department of Geological Sciences, Jadavpur University: Rashtriya Uchchattar Shiksha Abhiyan (RUSA 2.0) from Ministry of Human Resource Development, India, Promotion of University Research and Scientific Excellence from DST (Department of Science and Technology, India), Fund for Improvement of Science and Technology (FIST-Phase II) from DST and Centre of Advanced Studies (CAS-phase VI) from UGC. The authors express their gratitude to the members of the Arizona LaserChron centre, in particular Mark Pecha and Nicky Giesler, for their assistance while conducting the LA–ICP–MS analyses. We are grateful to Dr. K. A. Cutts for her constructive inputs on earlier versions of this manuscript. We express our sincere gratitude to Prof. N. Chatterjee and one anonymous reviewer whose erudite comments greatly improved the manuscript. We thank Prof. N. V. Chalapathi Rao for his competent editorial handling.
Publisher Copyright:
© 2019 John Wiley & Sons, Ltd.
PY - 2020/4/1
Y1 - 2020/4/1
N2 - The north-eastern part of the Chotanagpur Granite Gneiss Complex (CGGC) in the East Indian shield contains enclaves of migmatitic pelitic granulites (PG) within felsic orthogneiss (FOG). Field observations, petrology and geochronology (LA–MC–ICP–MS U–Pb dating of zircon and EPMA Th–U–total-Pb dating of monazite) of the PG suggest two distinct metamorphic events. The earliest event M1, which is characterized by high-temperature (>850°C) granulite facies metamorphism, occurred in the timespan of ~1680–1580 Ma. Extensive dehydration melting of biotite + sillimanite + quartz-rich protoliths led to stabilization of the restitic assemblage (garnet + alkali-feldspar + quartz + sillimanite + ferrian-ilmenite) together with large volumes of felsic melts (leucosomes). Collisional tectonics followed by delamination and asthenospheric upwelling could have triggered the M1 event. Subsequently, at ~1470–1400 Ma, the igneous protolith of the host FOG intruded and hydrated the PG. Thereafter, a second metamorphic event, M2, accompanied by compressional structures, affected both the rock types. A clockwise P–T path that culminated at ≥10 kbar ~760–850°C and is followed by a steeply decompressive retrograde path characterizes this event. The P–T path and the inferred geothermal gradient (<27°C/km) are compatible with a continent–continent collisional setting. Geochronological findings suggest a protracted orogeny for the M2 event with its major pulse during ~970–950 Ma. When combined with the published information, this study supports the view that a large (if not the entire) portion of the Indian shield and the granulite terranes of east Antarctica share similar tectonothermal events that led to the formation of two supercontinents, Columbia and Rodinia.
AB - The north-eastern part of the Chotanagpur Granite Gneiss Complex (CGGC) in the East Indian shield contains enclaves of migmatitic pelitic granulites (PG) within felsic orthogneiss (FOG). Field observations, petrology and geochronology (LA–MC–ICP–MS U–Pb dating of zircon and EPMA Th–U–total-Pb dating of monazite) of the PG suggest two distinct metamorphic events. The earliest event M1, which is characterized by high-temperature (>850°C) granulite facies metamorphism, occurred in the timespan of ~1680–1580 Ma. Extensive dehydration melting of biotite + sillimanite + quartz-rich protoliths led to stabilization of the restitic assemblage (garnet + alkali-feldspar + quartz + sillimanite + ferrian-ilmenite) together with large volumes of felsic melts (leucosomes). Collisional tectonics followed by delamination and asthenospheric upwelling could have triggered the M1 event. Subsequently, at ~1470–1400 Ma, the igneous protolith of the host FOG intruded and hydrated the PG. Thereafter, a second metamorphic event, M2, accompanied by compressional structures, affected both the rock types. A clockwise P–T path that culminated at ≥10 kbar ~760–850°C and is followed by a steeply decompressive retrograde path characterizes this event. The P–T path and the inferred geothermal gradient (<27°C/km) are compatible with a continent–continent collisional setting. Geochronological findings suggest a protracted orogeny for the M2 event with its major pulse during ~970–950 Ma. When combined with the published information, this study supports the view that a large (if not the entire) portion of the Indian shield and the granulite terranes of east Antarctica share similar tectonothermal events that led to the formation of two supercontinents, Columbia and Rodinia.
KW - Chotanagpur Granite Gneiss Complex
KW - East Indian shield
KW - Th–U–total Pb monazite dating
KW - U–Pb zircon dating
KW - pelitic granulite
KW - phase equilibria modelling
KW - supercontinental cycle
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U2 - 10.1002/gj.3552
DO - 10.1002/gj.3552
M3 - Article
AN - SCOPUS:85068518399
SN - 0072-1050
VL - 55
SP - 2851
EP - 2880
JO - Geological Journal
JF - Geological Journal
IS - 4
ER -