Early Pleistocene Multiproxy Record From Dove Basin, Scotia Sea: New Data to Evaluate the 41kyr World Problem

There is broad consensus that late Pleistocene climate change is paced at precessional and obliquity frequencies that are coherent with insolation received at critical latitudes in the Northern Hemisphere. Climate variance at the eccentricity frequency is less well understood, though may reflect expanded ice sheet growth during particularly low summer heating maxima that occur at 100 kyr frequencies due to the strong amplitude modulation of precession by eccentricity. This effect would be further enhanced by subsequently larger, non-linear crustal rebound feedbacks on the ensuing deglaciation. However, there is no consensus concerning the cause of observed glacial-interglacial patterns in the early Pleistocene when globally-integrated proxy records, such as benthic δ¹⁸O, appear to be dominated by the obliquity component of the orbital cycles, with only weak to absent variance seen at precessional and eccentricity frequencies.

Here, we test the Raymo et al. (2006) hypothesis that variance in Antarctic Ice Sheet (AIS) volume and climate at precessional frequencies in the early Pleistocene is overprinted by anti-phased precessional signals in Northern Hemisphere ice sheets. This phenomenon would result in an apparent obliquity-dominated world. Using sediment recovered on the IODP Leg 382 expedition, we reconstruct local climate signals in the Dove and Pirie Basins of the Scotia Sea. In particular, we analyze physical, sedimentological, and faunal properties of the highly-resolved and continuous sedimentary records recovered from IODP Site U1537. This site is located in "Iceberg Alley," a region that records iceberg and meltwater discharge on a background sedimentation pattern determined by regional climate, thus allowing us to reconstruct the timing, frequency, and phasing of the evolution of this part of the Southern Ocean and the nearby AIS. This project will provide an important historical context to extend understanding of AIS response to a warmer world.