Expedition Objective Research: Investigating Antarctic Cryosphere Changes at Wilkes Land During the Oligocene and Presumed "Stable" Icehouse World of the Late Miocene

南极洲的关键部分？由于缺乏来自该地区的高质量气候数据，美国的气候和冰冻圈历史仍然不确定。特别是渐新世沉积档案，其中包括中第三纪。渐新世（一个气候-冰量变异性放大的时期）和中新世晚期，当时冰盖的相对稳定性仍然存在高度争议，这是破译南极洲气候历史的主要缺失部分。综合海洋钻探计划远征318队前往威尔克斯岛的目标是调查南极洲的冰川历史，从温室世界（全球变暖，几乎没有冰川冰的时代）到冰屋世界（大陆大小的冰盖时代）。威尔克斯地区对于理解这段历史至关重要，因为数值模型表明，该地区是东南极洲最后一个被冰川覆盖的地区之一。这使得东南极洲的这部分地区对过去的气候变化最为敏感，对未来的变化也更加脆弱。这项研究有两个重点。首先，利用高分辨率粒度记录确定渐新世冰原和各种冰流到达南极海岸线的时间，确定冰筏碎屑（IRD）的物源记录，利用IRD角闪石颗粒的Ar - Ar测年来限制冰山的来源。其次，研究了晚中新世（距今1200万年至1100万年）的一次海洋变暖事件，该事件似乎与Prydz湾的一次超过300公里的重大冰川退缩同步。这将通过开发来自U1361遗址晚中新世地层的底栖和可能的浮游有孔虫和有孔虫生物相的配对高分辨率稳定同位素和Mg/ Ca比值记录来完成，然后将它们与Prydz湾记录相关联。该项目的结果将首次提供来自南极附近地点的必要数据，以测试假设和回答有关冰窖世界开始（渐新世）和冰盖被认为相对稳定（晚中新世）的时间间隔期间南极冰盖的时间和范围的尚未解决的问题。此外，这些结果也将是气候建模者更好地了解这些时间间隔内冰盖动态的关键。该项目的主要教育外展目标是通过为三名本科生和一名研究生制定本科生研究和指导计划，激励和教育下一代南极研究人员。这与PI在社区和教育推广工作中的长期承诺是一致的。作为教育外展的一部分，PI将主持由海洋领导组织的巡游后视频会议，为在探险期间参加视频会议的学校举办。其他的推广活动包括在全国六个主要博物馆进行演讲和实践示范。

Critical pieces of Antarctica?s climatic and cryospheric history remain uncertain owing to a lack of high quality climate data from this region. In particular, sedimentary archives deposited during the Oligocene, which includes the ?mid? Oligocene (a time of amplified climate-ice volume variability), and the late Miocene when the relative stability of the ice sheet is still highly debated, are major missing pieces in deciphering the climate history of Antarctica. The goal of Integrated Ocean Drilling Program Expedition 318 to Wilkes land was to investigate the glacial history of Antarctica from the Greenhouse World, a time of global warmth, with little to no glacial ice, to the Icehouse World, a time of continental size ice sheets. The Wilkes Land area is critical in understanding this history as numerical models suggest that this region was among the last areas of East Antarctica to become glaciated. This makes this part of East Antarctica the most sensitive to climate changes in the past and more vulnerable to future change. This research has two major foci. First, determining the timing when the ice sheet and various ice streams reached the Antarctic coastline during the Oligocene using high-resolution grain size records to identify ice rafted debris (IRD) provenance records using Ar Ar dating of hornblende grains from the IRD to constrain the source of icebergs. Second, examining an oceanic warming event during the Late Miocene (12-11 million years BP) that appears to be synchronous with a significant glacial retreat of over 300 km in Prydz Bay. This is will be accomplished by developing paired high-resolution stable isotope and Mg/ Ca ratio records from benthic and possibly planktonic foraminifers and foraminiferal biofacies from Late Miocene strata from Site U1361 and then correlate them to the Prydz Bay records. The results from this project will provide, for the first time, the requisite data from a site proximal to Antarctica to test hypotheses and answer yet unresolved questions related to the timing and extent of the Antarctic ice sheet during the start of the icehouse world (Oligocene) and during a time interval when the ice sheet was considered to be relatively stable (Late Miocene). Additionally, these results will also be key for climate modelers in developing a better understanding of ice sheet dynamics during these time intervals.The main educational outreach goal of this project is to inspire and educate the next generation of Antarctic researchers by developing an undergraduate research and mentoring program for three undergraduate students and one graduate student. This is in tune with a long-term commitment of the PI working in community and educational outreach efforts. As part of educational outreach, the PI will host post-cruise video conferences being organized by Ocean Leadership for schools that participated in video conferencing during the expedition. Additional outreach activities include giving presentations and hands-on demonstrations to six major museums across the country.