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体，已经是全球平均海平面上升的主要原因。在长期变暖的背景下，它的命运是一个重大的不确定性话题。极地地区冰量减少导致海平面加速上升是一个重大关切，因为这是影响数百万人的沿海洪水增加的原因。该项目将揭示埋在南极洲阿蒙森海海底下的一个独特的地质档案，这将揭示南极西部冰盖在过去温暖气候中的表现。这些数据和见解可用于为沿海政策制定中使用的冰盖和海洋建模提供信息。该项目还将支持发展具有竞争力的美国STEM劳动力。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研究课程的门户，该项目将通过资助现有女博士的教育来提高妇女对科学的参与。该项目的目标是国际海洋探索计划第379次考察队在阿蒙森海钻探的上新世早期沉积记录中，西南极冰盖在几个冰川-间冰期周期中的长期变化。资料收集包括：1）阿蒙森海和南极半岛地区冰筏碎屑和陆棚杂岩的砂源及其来源; 2）根据粒度记录和水流强度和相互作用的重建计算沉积结构和可分选粉砂;和3）与阿蒙森海大陆架现有数据相比，大陆隆起沉积物的大量物源，南极底层水形成的路径。的反射光谱和比色法（RSC）和X射线荧光扫描仪（XRF）数据的循环地层框架内的结果进行了分析，以深入了解轨道强迫的高纬度过程。 上新世早期的气候适宜期（PCO）约为4.5- 4.1Ma，是深海稳定同位素和海表温度记录中公认的一个主要暖期。这一时期也与全球平均海平面最高点20米相吻合，需要南极洲冰量损失的贡献。将对以下假设进行检验：1）在PCO ~4.5 Ma开始时，西南极冰盖从大陆架退缩，打破了亚冰盾融化和冰山崩解的增加，2）在~4.5 Ma之后，随着大陆架在冰川终止期间暴露，密集的陆架水通过斜坡通道倾泻而下。该项目将首次揭示南极西部冰盖如何在当前“冰库”期~3.3 Ma开始之前在温暖的气候状态下运行。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

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