West Antarctic Ice-sheet Change and Paleoceanography in the Amundsen Sea Across the Pliocene Climatic Optimum

上新世气候最适期西南极冰盖变化与阿蒙森海古海洋学

• 批准号: 2114839
• 负责人: Sandra Passchier
• 金额: $ 41.06万
• 依托单位: Montclair State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2114839&HistoricalAwards=false
• 关键词: West; Antarctic; Ice; sheet; Change

The West Antarctic Ice Sheet is the most vulnerable polar ice mass to warming and already a major contributor to global mean sea level rise. Its fate in the light of prolonged warming is a topic of major uncertainty. Accelerated sea level rise from ice mass loss in the polar regions is a major concern as a cause of increased coastal flooding affecting millions of people. This project will disclose a unique geological archive buried beneath the seafloor off the Amundsen Sea, Antarctica, which will reveal how the West Antarctic Ice Sheet behaved in a warmer climate in the past. The data and insights can be used to inform ice-sheet and ocean modeling used in coastal policy development. The project will also support the development of a competitive U.S. STEM workforce. Online class exercises for introductory geology classes will provide a gateway for qualified students into undergraduate research programs and this project will enhance the participation of women in science by funding the education of current female Ph.D. students.The project targets the long-term variability of the West Antarctic Ice Sheet over several glacial-interglacial cycles in the early Pliocene sedimentary record drilled by the International Ocean Discovery Program (IODP) Expedition 379 in the Amundsen Sea. Data collection includes 1) the sand provenance of ice-rafted debris and shelf diamictites and its sources within the Amundsen Sea and Antarctic Peninsula region; 2) sedimentary structures and sortable silt calculations from particle size records and reconstructions of current intensities and interactions; and 3) the bulk provenance of continental rise sediments compared to existing data from the Amundsen Sea shelf with investigations into downslope currents as pathways for Antarctic Bottom Water formation. The results are analyzed within a cyclostratigraphic framework of reflectance spectroscopy and colorimetry (RSC) and X-ray fluorescence scanner (XRF) data to gain insight into orbital forcing of the high-latitude processes. The early Pliocene Climatic Optimum (PCO) ~4.5-4.1 Ma spans a major warm period recognized in deep-sea stable isotope and sea-surface temperature records. This period also coincides with a global mean sea level highstand of 20 m requiring contributions in ice mass loss from Antarctica. The following hypotheses will be tested: 1) that the West Antarctic Ice Sheet retreated from the continental shelf break through an increase in sub iceshelf melt and iceberg calving at the onset of the PCO ~4.5 Ma, and 2) that dense shelf water cascaded down through slope channels after ~4.5 Ma as the continental shelf became exposed during glacial terminations. The project will reveal for the first time how the West Antarctic Ice Sheet operated in a warmer climate state prior to the onset of the current “icehouse” period ~3.3 Ma.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.

西南极冰盖是最容易受到变暖影响的极地冰块，已经成为全球平均海平面上升的主要贡献者。鉴于长期变暖，它的命运是一个主要不确定的话题。极地地区冰块减少导致海平面加速上升是一个主要关切，因为这是影响数百万人的沿海洪灾增加的一个原因。该项目将披露一个埋藏在南极阿蒙森海海底下的独特地质档案，它将揭示西南极冰盖过去在气候变暖时的表现。这些数据和见解可以用来为沿海政策制定中使用的冰盖和海洋模型提供信息。该项目还将支持发展一支有竞争力的美国STEM劳动力队伍。地质学入门课程的在线课堂练习将为合格的学生提供进入本科生研究项目的大门，该项目将通过资助目前女性博士生的教育来加强女性对科学的参与。该项目旨在研究国际海洋发现计划(IODP)在阿蒙森海钻探的379号沉积记录中，在上新世早期几个冰川-间冰期周期中南极西部冰盖的长期变化。收集的数据包括：1)阿蒙森海和南极半岛区域内冰排碎屑和陆架硅质岩的沙源及其来源；2)沉积结构和可分类粉砂的计算；3)根据粒度记录和重建水流强度和相互作用的计算；3)将大陆隆起沉积物的大量来源与阿蒙森海大陆架的现有数据进行比较，并调查作为南极底水形成途径的下坡洋流。结果在反射光谱和比色法(RSC)和X射线荧光扫描仪(XRF)数据的旋回地层学框架内进行了分析，以深入了解高纬度过程的轨道强迫。上新世早期气候最佳期(PCO)约4.5-4.1 Ma，是深海稳定同位素和海温记录中公认的主要暖期。这一时期也恰逢全球平均海平面高度为20米，这就要求南极的冰块减少。将检验以下假设：1)西南极冰盖在PCO~4.5 Ma开始时，通过亚冰盖融化和冰山崩解的增加而从大陆架撤退；2)在~4.5 Ma之后，随着大陆架在冰川终止期间暴露，致密的陆架水通过斜坡水道倾泻而下。该项目将首次揭示西南极冰盖在当前冰库时期开始前(约3.3 Ma)是如何在较温暖的气候状态下运行的。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

West Antarctic Ice Sheet Dynamics in the Amundsen Sea Sector since the Late Miocene?Tying IODP Expedition 379 Results to Seismic Data

晚中新世以来阿蒙森海区西南极冰盖动态？将 IODP 探险 379 结果与地震数据联系起来

• DOI: 10.3389/feart.2022.976703
• 发表时间: 2022
• 期刊: Frontiers in Earth Science
• 影响因子: 2.9
• 作者: Gille-Petzoldt Johanna;Gohl Karsten;Uenzelmann-Neben Gabriele;Gr?tzner Jens;Klages Johann P.;IODP Expedition 379 Scientists
• 通讯作者: IODP Expedition 379 Scientists

Pliocene Glacial-Interglacial Cyclicity in Sedimentation Offshore the Amundsen Sea, West Antarctica

南极洲西部阿蒙森海近海沉积物的上新世冰川-间冰期循环

• 发表时间: 2022
• 期刊: IL
• 作者: Passchier, Sandra

Examining ocean currents off West Antarctica through particle-size analyses of a sediment core

通过沉积物核心的粒度分析检查西南极洲附近的洋流

• 发表时间: 2022
• 期刊: 14th Annual GS-LSAMP/NNJ-B2B STEM Research Conference
• 作者: Mino-Moreira, Lisbeth