T197 Mass Extinctions I: Past, Present, and Future?

Tuesday, 24 October 2017
8:00 AM - 12:00 PM
Room 608

PALEOSOLS INDICATE STABLE WET FOREST ENVIRONMENTS IN CENTRAL INDIA ACROSS THE K-PG

Paper number: T197-7
Program: Technical Sessions
Time: 9:30 AM – 9:45 AM

Authors

Abstract

While many workers have implicated Deccan Traps volcanism as a causal mechanism for the K-Pg extinction event, relatively little is known about paleoclimatic change in the region proximal to the Deccan Traps. Recent paleobotanical work in central India has provided some new constraints on paleoenvironmental conditions; however, no single pattern has emerged. To test among these possible environments, intertrappean paleosols (“boles”) from the eastern edge of the Deccan Traps were sampled for bulk geochemical analysis to determine broad changes in precipitation around the K-Pg boundary. Red boles (N = 12) from three sites were sampled, with paleosols identified by the presence of carbonate nodules (pre-K-Pg), reduction haloes, root traces, compression plant fossils, and pedogenic slickensides. Paleosols were moderately developed, with A-Bw-C-R or A-Bt-C-R horizonation, most like modern Alfisols (forest soils). Sample ages range from Maastrichtian and Danian, with the K-Pg boundary locally correlated to a basalt flow sequence without any intertrappean beds. Mean annual precipitation estimates derived from unaltered or minimally altered red claystone paleosols averaged 948 mm yr-1, using CIA-K (avg = 73.4), potentially slightly increasing from the Cretaceous (839 mm yr-1) to the Paleogene (1021 mm yr-1). This paleoprecipitation estimate corresponds well to much of the paleobotanical data, as well as to estimates from red boles in the Western Ghat province and in Meghalaya, suggesting broadly similar paleoclimatic conditions over much of India during the K-Pg. Overall, paleosols suggest mesic, subtropical conditions. Taken with the paleobotanical data, this potentially indicates that central India was a primarily wet forest environment in a seasonal subtropical region before, during, and after the K-Pg extinction. Further analyses will be undertaken to explore the extent of the wet forest environment and the possibility of a precipitation increase across the K-Pg.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-302636

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