1. Geochronology of the 983-Ma Chilka Lake Anorthosite, Eastern Ghats Belt, India: Implications for Pre-Gondwana Tectonics.
- Author
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Chatterjee, Nilanjan, Crowley, James L, Mukherjee, Amalbikash, and Subhasish Das
- Subjects
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GEOLOGICAL time scales , *ANORTHOSITE , *MONAZITE , *ZIRCON , *GEOCHRONOMETRY , *METAMORPHISM (Geology) , *STRUCTURAL geology - Abstract
U-Pb zircon dating indicates that the Balugaon Anorthosite Massif of the Chilka Lake Domain, Eastern Ghats Belt, India, crystallized at 983.0 ± 2.5 Ma, ∼200 m.yr. earlier than previously inferred from ferrodiorite that intruded the massif. An integration of the new date with published structural data indicates that the anorthosite intruded a crust that was deformed twice before the intrusion. Furthermore, U-Th-Pb chemical dating of monazite cores (714 ± 11 Ma) and rims (655 ± 12 Ma) yields results consistent with progressive high-grade metamorphism of the anorthosite, and monazite + allanite rims (463 ± 22 Ma) around apatite indicate low-grade pan-African thermal activity. The 714- 655-Ma dates possibly correspond to convergence and oblique collision between the Eastern Ghats-Rayner Block and western Australia in the mid-Neoproterozoic. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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