Digging Deeper with the JR100: Extending high resolution paleoclimate records from the Chilean Margin to the Eemian

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The southeast Pacific is home to the largest temperate ice masses in the Southern Hemisphere, the Northern and Southern Patagonia Icefields, which contribute a disproportionate amount to modern sea level rise relative to other mountain glaciers. The climate impacts of future ice loss from the Patagonia icefield remain uncertain, but are expected to lead to significant variations in this region of the southern hemisphere with likely impacts to ocean circulation, sea level rise, and the global climate. This award funds a month-long research expedition from Tahiti to Punta Arenas, Chile to collect a depth transect of sediment cores from the southeast Pacific. The cores will enable investigation of oceanographic change in Chilean coastal waters and climate variability on the South American continent over the last 140,000 years. Twenty-six scientists from institutions across the country will participate, including many young investigators, with an emphasis on underrepresented groups. The primary goal of the project is to collect six, ~100 meters long sediment cores from the Chilean Margin (36-46°S, 829-3858 m) to investigate links between oceanographic changes at the northern margin of the Antarctic Circumpolar Current and climate variability on the South American continent over one glacial-interglacial cycle and two glacial terminations. The new cores will enable reconstruction of surface and intermediate water variability at centennial-to-millennial resolution, which will extend available records from previous coring expeditions, thus providing a record of the MIS 5e-5d glacial inception and permitting comparison of Southern Hemisphere records of the last and previous interglacial (Holocene vs. Eemian) as well as glacial terminations I and II. The expedition will include high-resolution pore water analysis to reconstruct the LGM seawater density profile in the Southeast Pacific. Cores will be scanned at sea to maximize shipboard data analysis. Post-cruise x-ray fluorescence (XRF) scanning will be used to verify the initial shipboard splices. The project also involves post-cruise generation of high-resolution sea surface and intermediate water temperature records from two of the six sites using 18O and Mg/Ca measurements in planktonic and benthic foraminifera. Ba/Ca and Nd/Ca data will be used to trace changes in river inputs to the coastal region as means of reconstructing changes in the Patagonian glaciers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.