Climate change and ecosystem transformation: plate wax evidence from Indian Ocean drilling

Dr. Sarah Feakins
Professor – USC Dornsife
Earth Sciences
Host: Dr. Jessica Whiteside

Friday, April 19, 2024
1 pm – CSL 422 (speaker will be virtual)
or via zoom

Abstract

Plants – from lush rainforests to desert shrublands – map climatic differences on the landscape. The waxy molecules coating plant leaves are some of the most resilient biochemicals made by plants and they contribute to the sedimentary legacy of past environment, archived in deep sea sediments. The International Ocean Discovery Program has recently drilled the two largest submarine fans in the world, the Bengal Fan (Expedition 354) and Indus Fan (Expedition 355). These megafans yield thick deposits of dominantly terrestrial organic matter derived from the Ganges-Brahmaputra and Indus River systems respectively. In addition, legacy cores from the Gulf of Aden (Expedition 24) contain wind-blown terrestrial organic material from NE Africa. From each of these expeditions we have uncovered a record of vegetation and climate change. Plant waxes are key to this story as their C isotopic composition reflects photosynthetic pathway and their H isotopic composition that of precipitation. Dual analyses in the same plant wax molecules allow climate and ecology to be tracked in tandem. Using this approach, we answer longstanding questions as to whether changes in monsoon rainfall coincided with the expansion of C4 grasslands.