| Summary: | Funds are provided to allow the PIs to develop a continuous record of changes in the Arctic Ocean in response to climatic cooling and growth of ice sheets in the Early to Middle Pleistocene based on sediment cores from the western Arctic Ocean. They will utilize a suite of proxies (microfaunal assemblages, stable and radiogenic isotopes, biomarkers, sediment mineralogy and elemental composition and grain size) to reconstruct variations in glacial inputs, sea ice, and water circulation. The use of paleobiological and geochemical proxies will be greatly enhanced by a unique sediment core that has a rich calcareous microfossil record extending through most of the Quaternary and potentially into the Pliocene, unlike other cores from the Arctic Ocean. This is a unique find that they can capitalize on as Arctic cores typically preserve calcareous microfossils only in Late Quaternary sediments. Age control will be achieved by paleomagnetic, 10Be, Sr-isotope, and cyclostratigraphic methods. This research will allow them to test whether there was an overall progressive growth in ice sheets and sea-ice cover and if sea ice and continental glaciers changed synchronously. They will also test whether the Mid Pleistocene Transition led to the growth of a super-thick Laurentide Ice Sheet by analyzing changes in glacial inputs from the northern Laurentide margin, with a multi-century scale record for the threshold glaciation ca. 650 ka, which initiated the icehouse world.
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