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

合作研究：横贯南极山脉高海拔冲积扇的激活——东南极冰缘沿上皮里奥-更新世温暖的代表

• 批准号: 1043554
• 负责人: Jane Willenbring
• 金额: $ 28.74万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1043554&HistoricalAwards=false
• 关键词: Collaborative; Research; Activation; elevation; alluvial

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.

智力优势：PI建议解决的问题，是否冰表面融化区在高海拔地区的温暖的气候阶段，在跨南极山脉。ANDRILL计划钻探的沉积物岩心证据表明，罗斯海的开放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，因为寒冷的冰川可能反应太慢，无法记录短暂的温暖。问题还围绕着可能对区域气候和冰盖边缘进行的轨道控制。北方半球太阳辐射在赤道和岁差时间尺度上被认为通过海洋或大气联系控制南极气候，但新的思维表明，南半球夏季的持续时间可能更重要。PI建议使用跨南极山脉的高海拔冲积层作为内陆温暖的代表。这些相对年轻的风扇，渠道和泥石流堤坝脱颖而出，作为可见的证据，在其他古老的，冻结的景观存在融水。根据对奥林匹斯山脉冲积扇的初步分析，这些沉积物是轨道时间尺度上发生的罕见融化事件的敏感记录器。他们的研究将1）使用航空摄影，卫星图像和GPS辅助实地调查绘制冲积矿床，以确定水源并量化影响融水生产的参数，2）使用OSL，宇宙成因核素和夹层火山灰年表确定这些矿床内的地层序列，3）使用成对核素分析来估计暴露和埋藏时间，以及沉积和侵蚀速率，更广泛的影响：这项研究将产生一个记录的内陆融化从邻近的网站冰盖边缘，以帮助确定控制区域气候沿着边缘的东南极冰盖，以帮助冰盖和海平面模拟研究。该提案将支持几个研究生和本科生。一名博士生将得到现有资金的支持。PI将与多所K12学校合作，从南极洲进行采访和网络广播，并将在实地考察季节结束后对教室进行后续访问。