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？S，由于缺乏该地区的高质量气候数据，气候和冰冻圈的历史仍然不确定。尤其是渐新世沉积的沉积档案，包括？中期？渐新世(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存在高度争议，是破译南极洲气候历史的主要缺失部分。对威尔克斯陆地的综合海洋钻探计划318的目标是调查从温室世界到冰屋世界的南极洲冰川历史。温室世界是全球变暖的时期，几乎没有冰川，冰屋世界是大陆大小的冰原。威尔克斯陆地地区对理解这一历史至关重要，因为数值模型表明，该地区是东南极最后几个冰川形成的地区之一。这使得东南极的这一部分过去对气候变化最敏感，也更容易受到未来变化的影响。这项研究有两个主要焦点。首先，使用高分辨率的粒度记录确定冰盖和各种冰流在渐新世到达南极海岸线的时间，以确定冰筏碎片(IRD)的来源记录，使用IRD的角闪石颗粒的Ar-Ar测年来限制冰山的来源。第二，研究了中新世晚期(1200万-1100万年前)的一次海洋变暖事件，该事件似乎与普里兹湾300多公里的显著冰川消退同步。这将通过从U1361站点晚中新世地层的底栖生物和可能的浮游有孔虫和有孔虫生物相开发成对的高分辨率稳定同位素和镁/钙比记录来实现，然后将它们与普里兹湾记录进行对比。该项目的结果将首次提供南极附近地点的必要数据，以检验假设并回答与冰库世界开始(渐新世)和冰盖被认为相对稳定的一段时间间隔(中新世晚期)南极冰盖的时间和范围有关的尚未解决的问题。此外，这些结果也将是气候模型人员在这些时间间隔期间更好地了解冰盖动力学的关键。该项目的主要教育推广目标是通过为三名本科生和一名研究生开发一个本科生研究和指导计划来激励和教育下一代南极研究人员。这与国际和平协会在社区和教育外展工作中的长期承诺是一致的。作为教育推广活动的一部分，PI将主办由Ocean Leaders为参加探险期间视频会议的学校组织的邮轮后视频会议。其他外展活动包括向全国六家主要博物馆进行演讲和动手演示。

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.