Substantiation of Reunion plume induced prolonged magmatic pulses (ca. 70.5-65.5 Ma) of the Deccan LIP in the Chhotanagpur Gneissic Complex, eastern India: Constraints from Ar-40/Ar-39 geochronology

摘要

abstract_textpThis study presents Ar-40/Ar-39 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 Ar-40/Ar-39 plateau ages, which range in age from ca. 70.5 to 65.5 Ma, suggest prolonged (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 +/- 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./p/abstract_text