Collaborative Research: Testing the Linchpin of WAIS Collapse with Diatoms and IRD in Pleistocene and Late Pliocene Strata of the Resolution Drift, Amundsen Sea, Antarctica

合作研究：用硅藻和 IRD 测试南极洲阿蒙森海分辨率漂移的更新世和上新世晚期地层中 WAIS 塌陷的关键

• 批准号: 1939139
• 负责人: Reed Scherer
• 金额: $ 27.08万
• 依托单位: Northern Illinois University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1939139&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; Linchpin; WAIS

Part I, Non-technical Abstract Concerns that the West Antarctic Ice Sheet (WAIS) might be susceptible to releasing its ice as giant icebergs into the Southern Ocean due to a warming climate, raising global sea level, were first expressed more than 40 years ago. To best-assess this threat, scientists need to know whether such events occurred in the geologically recent past, during warm intervals of past glacial-interglacial cycles. Ocean drilling near the most vulnerable sector of the WAIS, in 2019, yielded seafloor geologic records demonstrating times when icebergs dropped large volumes of sands and pebbles, called ice-rafted detritus (IRD) in deep water of the Amundsen Sea. Occurring together with IRD that was eroded from bedrock beneath the ice sheets, there are abundant microfossils of diatoms (algal plankton), which indicate high biological productivity in the open ocean. The new sediment cores provide a complete, uninterrupted record of a time of dramatic fluctuations of ice sheet extent that occurred over the last 3 million years. Therefore, they provide the means to obtain clear answers to the question whether ice sheet collapse occurred in the past and offering clues to its potential future. This project will investigate sediment intervals where IRD coincides with evidence of high diatom production, to test whether these two criteria indicate rapid ice sheet collapse. Geochemical analysis of IRD pebbles will help trace the source of the icebergs to likely on-land sites. By analyzing conditions of high diatom and IRD accumulation in deep ocean sediment, where local coastal influences can be avoided, we will assess oceanographic and climatic conditions associated with past ice sheet collapse events. Diatoms provide powerful evidence of temperature and ocean productivity changes in the past, that, when linked to time, can translate into rates of ice sheet drawdown. These results will provide critical data for designing, constraining and testing the next suite computer models that can determine the likelihood and timing of future ice sheet collapse in a warming world. The project will include training of undergraduate and graduate students from diverse backgrounds, and the public will be introduced to Antarctic science and engaged through several different outreach efforts.Part 2, Technical AbstractNew drillcores from the Amundsen Sea, Antarctica (IODP Expedition 379) contain a continuous record of oceanographic changes and iceberg rafted debris (IRD) spanning the last 5 million years. This study aims to identify the signature of retreat/collapse of the West Antarctic Ice Sheet (WAIS) in these continental margin, deep-sea sediments by quantitatively analyzing, in detail, diatom and IRD records across glacial-interglacial lithostratigraphic transitions to establish the timing and frequency of Late Pliocene and Pleistocene WAIS collapse events. The investigators will secure age constraints and diagnostic observations of marine paleoenvironmental conditions for selected interglacial intervals of cores from sites U1532 and U1533, using high resolution micropaleontology of diatom assemblages coupled with microstratigraphic analysis of IRD depositional events, while petrography, geochronology and thermochronology of iceberg rafted clasts will provide evidence of iceberg sources and pathways. Depositional paleotemperatures will be assessed via a new paleotemperature proxy based on quantitative assessment of morphologic changes in the dominant Southern Ocean diatom Fragilariopsis kerguelensis. Their results will contribute to parameterization of new ice sheet models that seek to reconstruct and forecast West Antarctic Ice Sheet behavior. This project will directly contribute to undergraduate education at an undergraduate-only college and at a public university that serves a demographic typified by first generation university students and underrepresented groups. Spanning geology, geochemistry, sedimentology, paleontology and paleoceanography, the proposed work will allow undergraduate students to develop diverse skills through hands-on research within a collaborative team that is dedicated to societally relevant research. The two graduate students will conduct original research and work alongside/mentor undergraduates, making for a well-rounded research experience that prepares them for success in future academic or employment sectors. The discoveries that come from this deep-sea record from West Antarctica will be communicated by students and investigators at national and international conferences and an array of public science outreach events.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

第一部分，非技术抽象的担忧是，西南冰期（WAIS）可能很容易释放其冰，因为由于气候变暖，全球海平面提高了巨型冰山，这是40多年前的表达。为了最好地评估这一威胁，科学家需要知道在过去的冰川间冰期周期的温暖间隔中，这种事件是否发生在地质上最近的过去。 2019年，海洋最脆弱的地区附近的海洋钻探产生了海底地质记录，证明了冰山在阿蒙森海深水中掉落大量的沙子和卵石，称为冰羊皮的碎屑（IRD）。 与IRD一起从冰盖下的基岩中侵蚀，有大量的硅藻（Algal Plankton），表明开阔的海洋生物学生产力很高。新的沉积物核心提供了过去300万年发生的冰盖范围波动的完整，不间断的记录。 因此，它们提供了对冰盖过去是否发生的问题的明确答案，并为其潜在的未来提供了线索。该项目将调查SECIENT间隔，其中IRD与高硅藻产生的证据相吻合，以测试这两个标准是否表明冰盖快速崩溃。对IRD卵石的地球化学分析将有助于将冰山的来源追溯到可能的陆上地点。通过分析可以避免局部沿海影响的深海沉积物中高硅藻和IRD积累的条件，我们将评估与过去的冰盖倒塌事件相关的海洋和气候状况。 硅藻为过去的温度和海洋生产率变化提供了有力的证据，当与时间链接时，可以转化为冰盖缩减的速度。这些结果将为设计，限制和测试下一个套件计算机模型提供关键数据，以确定在变暖世界中未来冰盖崩溃的可能性和时机。该项目将包括对来自不同背景的本科生和研究生的培训，公众将被介绍给南极科学，并通过几种不同的外展工作参与。第2部分，来自南极洲Amundsen Sea的技术摘要Drillcores（IODP Expedition 379）包含大洋变化和冰becergecectected raftged calafted pebris（IRD）的连续记录。这项研究旨在通过这些大陆边缘（WAIS）在这些大陆边缘，深海沉积物中确定撤退/崩溃的标志，通过详细分析冰川岩性岩性岩性质量结构术的详细分析，硅藻和IRD记录，以建立Pliocene和Pleappe pleappe的晚期频率和频率。研究人员将使用高分辨率的微分析学的高分辨率组合，以确保来自地点U1532和U1533的核心间隔的海洋古环境条件的年龄限制和诊断观察，并使用硅藻的高分辨率组合的高分辨率微生物结构学结合了与冰层学，冰层学，地球学的冰层学分析，并提供了质量学，地球的冰期分析。冰山的来源和路径。沉积古植物将通过基于对主要南部海洋硅藻的形态变化的定量评估来评估新的古过温代理。他们的结果将有助于新的冰盖模型的参数化，这些模型试图重建和预测西南极冰盖行为。该项目将直接为只有本科大学的大学和公立大学的本科教育做出贡献，该大学服务于第一代大学生和代表性不足的群体所构成的人群。涵盖地质学，地球化学，沉积学，古生物学和古文学学，拟议的工作将使本科生能够通过一支致力于社会相关研究的协作团队中的动手研究来发展多样的技能。两位研究生将与/导师本科生一起进行原创研究和工作，为全面的研究经验提供了准备，为他们在未来的学术或就业领域的成功做好准备。来自西南极洲这一深海记录的发现将由国家和国际会议的学生和调查人员传达，以及一系列公共科学宣传活动。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来通过评估来进行评估的。

项目成果

Latitudinal Variance in the Drivers and Pacing of Warmth During Mid‐Pleistocene MIS 31 in the Antarctic Zone of the Southern Ocean

南大洋南极区中更新世 MIS 31 期间温暖驱动因素和节奏的纬度变化

• DOI: 10.1029/2021pa004394
• 发表时间: 2022
• 期刊: Paleoceanography and Paleoclimatology
• 影响因子: 3.5
• 作者: Warnock, Jonathan P.;Reilly, Brendan T.;Raymo, Maureen E.;Weber, Michael E.;Peck, Victoria;Williams, Trevor;Armbrecht, Linda;Bailey, Ian;Brachfeld, Stefanie;Du, Zhiheng
• 通讯作者: Du, Zhiheng