Consequences of the Collision of India with Asia

Abstract:

The records for 18O in benthic foraminifera, 34S in marine barite, 13C in amber, 7Li in planktic foraminifera, and Mg to Ca in sea salt tell us that the collision of India with Asia 51 million years ago set the Earth’s environment on a new course. The relative quiescence of the previous 50 million years gave way to a drift in conditions which continues even now. The new regime is heralded by abrupt changes in the δ13C in amber and the δ34S in barite. I would like to think that the former is the result of a sharp drop in atmohpheric O2 and the latter as the result of an increase in sulfide deposition. These abrupt changes are followed by downward drifts in the δ13C of amber and in the Ca to Mg ratio in sea salt and upward drifts in the δ7Li in planktics and in the δ18O in benthics. As indicated by the δ13C in marine organic matter the CO2 content of the atmosphere decreased over this time interval. The likeliest cause for the changes are sea level lowering and mountain building.