Reconstructing Atmospheric Changes in Monsoon Regions Using Eolian Dust
Christopher Kinsley, Ph.D., 2019
David McGee, Advisor
This thesis generates new eolian dust records from monsoon regions to reconstruct changes in atmospheric circulation in response to forcing by high-latitude insolation and boundary condition change. In Chapters 2 and 3 I use 230Thxs-normalization to construct high-resolution dust flux records from sedimentary archives downwind from the West African and East Asian Monsoon regions respectively. The West African margin records show an interplay between NH summer insolation forcing and North Atlantic cooling, with abrupt increases in dust flux associated with Greenland stadials. A “Green Sahara” interval is identified from 60-50 ka, and a skipped precessional “beat” from 35-20 ka. The Shatsky Rise record at ODP Site 1208 shows variability associated with glacial-interglacial boundary conditions over the last 330 ka, exhibiting high dust during glacial times and a NH summer insolation control at times overriding the glacial-interglacial signal. In Chapter 4 I generate a 143Nd/144Nd record from isolated eolian material over the last 200 ka to examine Westerly Jet behavior in the Asian interior, which shows resolvable orbital-scale variability from 200 to 100 ka, implying a quicker shift of the Westerly Jet to the north of the Tibetan Plateau during times of high NH summer insolation and a strong Asian monsoon.