Abstract

Volcanism in the Deccan Traps of India occurred over at most three magnetic chrons, centered on a main reversed chron. Paleontological data indicate that this reversed chron must coincide with 29R, which contains the Cretaceous/Tertiary (K/T) boundary. Recent 40Ar-39 Ar data may therefore provide one of the best estimates of the absolute age of the K/T boundary, 65.7 ±2.0 Ma. Moreover, the Eurasian character of K/T boundary terrestrial faunas in India suggests that this was also close to the time of India-Asia collision. This is significantly earlier than generally recognized, and implies about 4000 km of continental shortening in the collision zone, probably absorbed jointly by crustal thickening and strike-slip extrusion.

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