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The influence of the Indian monsoon on productivity and sedimentation in the northern Bay of Bengal over the last glacial-interglacial cycle

By: Steve Phillips, Postdoctoral Fellow, UTIG

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The Indian monsoon drives seasonal changes in precipitation and runoff across India as well as circulation and productivity in the northern Indian Ocean. I will present a multi-proxy analysis of a sediment record (since 110 ka) from the offshore Mahanadi Basin recovered during the Indian National Gas Hydrate Program Expedition 01 (Site NGHP-01-19B) within the core convective region of the Indian monsoon. These results highlight the offshore Mahanadi Basin as a supply-dominated margin where terrigenous sedimentation is strongly influenced by monsoon intensity, and that biological productivity is likely limited by variation in monsoon-driven ocean stratification on glacial-interglacial timescales rather than a direct response to monsoon winds. Evidence of reduced chemical weathering and an increase in C4 plant material suggest more arid conditions between 70 and 10 ka. The mass-accumulation rate of CaCO3, a function of marine productivity, drastically increased between 70 and 10 ka and is correlated to a previously-documented increase in Bay of Bengal surface salinity. This evidence for a weakened summer monsoon and reduced stratification between 70 and 10 ka is correlated to elevated eastern Asian dust content in Greenland ice cores.

Host: Peter B. Flemings, UTIG

When: Fri Sep 30, 2016 10:30am – 11:30am Central Time