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$^{40}\rm{Ar}/^{39}\rm{Ar}$ geochronology; mafic dykes; Reunion plume; Deccan LIP; Chhotanagpur Gneissic Complex; eastern India

This study presents $^{40}\rm{Ar}/^{39}\rm{Ar}$ geochronology on the mafic dykes emplaced in the Damodar valley Gondwana sedimentary basins of the Chhotanagpur Gneissic Complex (CGC) to authenticate prolonged mafic magmatic activities during Maastrichtian period. A couple of earlier and one new $^{40}\rm{Ar}/^{39}\rm{Ar}$ plateau ages, which range in age from ca. 70.5 to 65.5 Ma, suggest prolonged ($\sim$5 myr) magmatic activities in the CGC. These syn- and pre-Deccan LIP magmatic intrusive activities in the CGC are supposedly related to the Reunion mantle plume. The reported age of 70.5 $\pm$ 0.9 Ma of a NE-trending mafic dyke emplaced within the Raniganj basin could probably be the earliest record of the Reunion mantle plume activity in the Indian shield. A number of other early magmatic rocks, related to the Reunion mantle plume induced Deccan LIP event, are also recorded elsewhere in the Indian shield and supportive of prolonged magmatic activities. Finally, this study also provides a better constraint on the initiation and lateral extent of the Reunion mantle plume induced Deccan LIP.

RAJESH K SRIVASTAVA¹ FEI WANG^{2 3 4} WENBEI SHI²

1. Centre of Advanced Study in Geology, Institute of Science, Banaras Hindu University, Varanasi 221 005, India.
2. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, P.R. China.
3. CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Beijing 100 101, P.R. China.
4. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100 049, P.R. China.

Published

15 March 2020

Manuscript received

14 November 2019

Manuscript revised

7 January 2020

Accepted

10 January 2020

Early published

Unedited version published online

Final version published online

16 March 2020