Collaborative Research: Activation of high-elevation alluvial fans in the Transantarctic Mountains - a proxy for Plio-Pleistocene warmth along East Antarctic ice margins

智力价值：PIs建议解决的问题是，在横跨南极山脉的温暖气候阶段，冰面融化区是否在高海拔地区形成。ANDRILL计划钻探的沉积物岩心的证据表明，罗斯海的开阔水域可能是上新世和更新世的温暖来源。问题是海洋的温暖是否渗透到内陆的冰盖边缘。冰川记录可能不适合回答这个问题，因为以冷为基础的冰川可能反应太慢，无法记录到短暂的温暖。问题还围绕着对区域气候和冰盖边缘可能的轨道控制。北半球在倾角和岁差时间尺度上的日照被认为是通过海洋或大气联系来控制南极气候的，但新的想法表明，南半球夏季的持续时间可能更重要。PIS建议使用横跨北极山脉的高海拔冲积沉积物作为内陆温暖的代用品。这些相对年轻的扇子、水道和泥石流堤坝突出地证明了在其他古老的冰冻景观中存在融水。根据对奥林匹斯山脉冲积扇的初步分析，这些沉积物是发生在轨道时间尺度上的罕见熔融事件的灵敏记录器。在他们的研究中，他们将1)使用航空摄影、卫星图像和GPS辅助实地勘测绘制冲积沉积物地图，以确定水源并量化影响熔融水产生的参数；2)使用OSL、宇宙成因核素和互层火山灰年代学来确定这些沉积物中的地层序列；3)使用成对核素分析来估计暴露和埋藏时间、沉积和侵蚀速率，4)使用微观和区域尺度的气候模拟来估计与融化事件相关的古环境条件。广泛的影响：这项研究将产生邻近冰盖边缘的内陆融化的记录，以帮助确定对南极东部冰盖边缘的区域气候的控制，以帮助冰盖和海平面模拟研究。该提案将支持几名研究生和本科生。一名博士生将得到现有资金的支持。PIS将与多所K-12学校合作，在南极洲进行访谈和网络广播，并在实地考察结束后对教室进行后续访问。

Intellectual Merit: The PIs propose to address the question of whether ice surface melting zones developed at high elevations during warm climatic phases in the Transantarctic Mountains. Evidence from sediment cores drilled by the ANDRILL program indicates that open water in the Ross Sea could have been a source of warmth during Pliocene and Pleistocene. The question is whether marine warmth penetrated inland to the ice sheet margins. The glacial record may be ill suited to answer this question, as cold-based glaciers may respond too slowly to register brief warmth. Questions also surround possible orbital controls on regional climate and ice sheet margins. Northern Hemisphere insolation at obliquity and precession timescales is thought to control Antarctic climate through oceanic or atmospheric connections, but new thinking suggests that the duration of Southern Hemisphere summer may be more important. The PIs propose to use high elevation alluvial deposits in the Transantarctic Mountains as a proxy for inland warmth. These relatively young fans, channels, and debris flow levees stand out as visible evidence for the presence of melt water in an otherwise ancient, frozen landscape. Based on initial analyses of an alluvial fan in the Olympus Range, these deposits are sensitive recorders of rare melt events that occur at orbital timescales. For their study they will 1) map alluvial deposits using aerial photography, satellite imagery and GPS assisted field surveys to establish water sources and to quantify parameters effecting melt water production, 2) date stratigraphic sequences within these deposits using OSL, cosmogenic nuclide, and interbedded volcanic ash chronologies, 3) use paired nuclide analyses to estimate exposure and burial times, and rates of deposition and erosion, and 4) use micro and regional scale climate modeling to estimate paleoenvironmental conditions associated with melt events.Broader impacts: This study will produce a record of inland melting from sites adjacent to ice sheet margins to help determine controls on regional climate along margins of the East Antarctic Ice Sheet to aid ice sheet and sea level modeling studies. The proposal will support several graduate and undergraduates. A PhD student will be supported on existing funding. The PIs will work with multiple K 12 schools to conduct interviews and webcasts from Antarctica and they will make follow up visits to classrooms after the field season is complete.