Timing and Duration of the LGM and Post-LGM Grounding Events in Whales Deep Paleo Ice Stream, Eastern Ross Sea Middle Continental Shelf

智力优势：来自罗斯海东部大陆架的证据表明，南极西部冰盖在末次冰期循环中前进和后退，但目前还不清楚冰盖是前进到大陆架边缘还是只是前进到大陆架中间。这两个端元情景提供了不同的解释，为什么，如何，以及何时南极西部冰盖振荡。PI建议从鲸鱼深获得地震，多波束和岩心数据，以评估两次接地冰向鲸鱼深盆地（罗斯海东部的西南极冰盖古冰流槽）的外部和中部大陆架推进的时间和持续时间。接地事件由地震可分辨的接地带楔形体表示。PI将从接地区diamict中收集原位底栖有孔虫的放射性碳年代，以及从覆盖接地区diamict的开阔海泥中收集酸不溶性有机物的斜坡热解放射性碳年代。PI将使用这些数据计算两次接地事件的持续时间。此外，PI将测试一个数值模型预测，西南极冰盖退缩必须涉及冰盖的海洋终点融化。将从活塞岩心中提取接地区孔隙水，以确定盐度和δ更广泛的影响：收集的数据将提供对末次冰期最大进退的时间和模式的限制，这些限制可以纳入对冰面高程变化的解释中。拟议的活动将提供宝贵的领域和研究培训本科生/研究生和路易斯安那州高中科学教师。这项研究将与初中和高中科学学生以及路易斯安那州立大学自然科学博物馆周末科学项目的游客互动分享。

Intellectual Merit: Evidence from the eastern Ross Sea continental shelf indicates that the West Antarctic Ice Sheet advanced and retreated during the last glacial cycle, but it is unclear whether the ice sheet advanced to the shelf edge or just to the middle shelf. These two end-member scenarios offer different interpretations as to why, how, and when the West Antarctic Ice Sheet oscillated. The PI proposes to acquire seismic, multibeam, and core data from Whales Deep, to evaluate the timing and duration of two advances of grounded ice to the outer and middle shelf of the Whales Deep Basin, a West Antarctic Ice Sheet paleo ice stream trough in eastern Ross Sea. Grounding events are represented by seismically resolvable Grounding Zone Wedges. The PI will collect radiocarbon dates on in situ benthic foraminifera from the grounding zone diamict as well as ramped pyrolysis radiocarbon dates on acid insoluble organics from open-marine mud overlying the grounding zone diamict. Using these data the PI will calculate the duration of the two grounding events. Furthermore, the PI will test a numerical model prediction that West Antarctic Ice Sheet retreat must have involved melting at the marine terminus of the ice sheet. Pore-water from the grounding zone diamict will be extracted from piston cores to determine salinity and δ18O values that should indicate if significant melting occurred at the grounding line.Broader impacts: The data collected will provide constraints on the timing and pattern of Last Glacial Maximum advance and retreat that can be incorporated into interpretations of ice-surface elevation changes. The proposed activities will provide valuable field and research training to undergraduate/graduate students and a Louisiana high-school science teacher. The research will be interactively shared with middle- and high-school science students and with visitors to the LSU Museum of Natural Science Weekend-Science Program.