Collaborative Research: Organic and Inorganic Geochemical Investigation of Hydrologic Change in East Antarctica in the 4 Million Years Before Full Glaciation

合作研究：全冰期前400万年南极洲东部水文变化的有机和无机地球化学研究

• 批准号: 1908399
• 负责人: Michael Bizimis
• 金额: $ 16.4万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-31 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1908399&HistoricalAwards=false
• 关键词: Collaborative; Research; Organic; Inorganic; Geochemical

The East Antarctic Ice Sheet holds the largest volume of freshwater on the planet, in total enough to raise sea level by almost two hundred feet. Even minor adjustments in the volume of ice stored have major implications for coastlines and climates around the world. The question motivating this project is how did the ice grow to cover the continent over thirty million years ago when Antarctica changed from a warmer environment to an ice-covered southern continent? The seafloor of Prydz Bay, a major drainage basin of the East Antarctic Ice Sheet (EAIS), has been drilled previously to recover sediments dating from millions of years prior to and across the time when inception of continental ice sheets occurred in Antarctica. The last remnants of plant material found as 'biomarkers' in the ocean sediments record the chemical signatures of rain and snowfall that fed the plants and later the expanding glaciers. Sediment carried by glaciers was also deposited on the seafloor and can be analyzed to discover how glaciers flowed across the landscape. Here, the researchers will identify precipitation changes that result from, and drive, ice sheet growth. This study will gather data and further analyze samples from the seafloor sediment archives of the International Ocean Discovery Program's (IODP) core repositories. Ultimately these findings can help inform temperature-precipitation-ice linkages within climate and ice sheet models. The project will support the training of three female, early career scientists (PhD & MS students, and research technician) and both PIs and the PhD student will continue their engagement with broadening participation efforts (e.g., Women in Science and Engineering Program; local chapters of Society for the advancement of Native Americans and Chicanos in Science and other access programs) to recruit undergraduate student participants from underrepresented minorities at both campuses and from local community colleges. Antarctic earth science education materials will be assisted by professional illustrations to be open access and used in public education and communication efforts to engage local communities in Los Angeles CA and Columbia SC. The researchers at the University of Southern California and the University of South Carolina will together study the penultimate moment of the early Cenozoic greenhouse climate state: the ~4 million years of global cooling that culminated in the Eocene/Oligocene transition (~34 Ma). Significant gaps remain in the understanding of the conditions that preceded ice expansion on Antarctica. In particular, the supply of raw material for ice sheets (i.e., moisture) and the timing, frequency, and duration of precursor glaciations is poorly constrained. This collaborative proposal combines organic and inorganic proxies to examine how Antarctic hydroclimate changed during the greenhouse to icehouse transition. The central hypothesis is that the hydrological cycle weakened as cooling proceeded. Plant-wax hydrogen and carbon isotopes (hydroclimate proxies) and Hf-Nd isotopes of lithogenous and hydrogenous sediments (mechanical weathering proxies) respond strongly and rapidly to precipitation and glacial advance. This detailed and sensitive combined approach will test whether there were hidden glaciations (and/or warm events) that punctuated the pre-icehouse interval. Studies will be conducted on Prydz Bay marine sediment cores in a depositional area for products of weathering and erosion that were (and are) transported through Lambert Graben from the center of Antarctica. The project will yield proxy information about the presence of plants and the hydroclimate of Antarctica and the timing of glacial advance, and is expected to show drying associated with cooling and ice-sheet growth. The dual approach will untangle climate signals from changes in fluvial versus glacial erosion of plant biomarkers. This proposal is potentially transformative because the combination of organic and inorganic proxies can reveal rapid transitions in aridity and glacial expansion, that may have been missed in slower-response proxies and more distal archives. The research is significant as hydroclimate seems to be a key player in the temperature-cryosphere hysteresis.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.

东南极冰盖拥有地球上最大的淡水，总共足以将海平面提高近200英尺。即使对存储的冰量进行的微小调整也对世界各地的海岸线和气候都有重大影响。激发该项目的问题是，当南极从温暖的环境变成冰冰覆盖的南部大陆时，冰是如何覆盖300万年前覆盖大陆的？先前已经对南极冰盖（EAIS）的主要排水盆地Prydz Bay的海底进行了钻探，以回收南极洲大陆冰片开始之前和整个大陆冰片之前数百万年的沉积物。在海洋沉积物中发现的“生物标志物”的最后残留物记录了降雨和降雪的化学特征，这些降雨和降雪量为植物和后来的冰川膨胀。冰川还沉积在海底上，可以分析以发现冰川如何流过整个景观。在这里，研究人员将确定由冰盖生长和驱动冰盖生长的降水变化。这项研究将收集数据并进一步分析国际海洋发现计划（IODP）核心存储库的海底沉积物档案中的样本。最终，这些发现可以有助于为气候和冰盖模型中的温度启发性冰键连接提供信息。该项目将支持对三位女性，早期职业科学家（博士和MS学生和研究技术员）的培训，PIS和PhD学生将继续他们参与参与工作（例如，科学和工程学计划中的妇女在科学和工程学计划中；当地社会社会的当地社会阶级，美国原住民和其他科学和其他访问计划中的社区参与者的训练学生都不在群体中，从而使学生群体不及格及其阶层。南极地球科学教育材料将得到专业插图的协助，以开放访问权限，并用于公共教育和传播工作，以吸引洛杉矶CA和Columbia SC的当地社区。南加州大学和南卡罗来纳大学的研究人员将共同研究新生代早期温室气候状态的倒数第二瞬间：在始新世/渐新世过渡（〜34 MA）中达到的约400万年的全球冷却时间。在对南极冰扩展之前的条件的理解中仍然存在很大的差距。特别是，冰盖的原材料（即水分）以及前体冰川的时间，频率和持续时间的供应受到限制。该协作提案结合了有机和无机代理，以检查温室中南极氢化气候如何变化到冰屋过渡。中心假设是随着冷却的进行，水文循环削弱了。植物蜡氢和碳同位素（氢化气候代理）以及岩性和氢源性沉积物（机械风化代理）的HF-ND同位素对降水和冰川促进的反应迅速。这种详细且敏感的组合方法将测试是否有隐藏的冰川（和/或温暖的事件），这些冰川效果会导致预一口气的间隔。将在沉积区域的Prydz Bay海洋沉积物核心上进行研究，以通过（并）从南极洲中心通过Lambert Graben运输（并且）。该项目将产生有关植物的存在和南极氢化气候以及冰川前进的时间的代理信息，并有望显示与冷却和冰层生长相关的干燥。双重方法将从河流生物标志物的河流变化与冰川侵蚀的变化中解开气候信号。该提议具有潜在的变革性，因为有机代理和无机代理的组合可以揭示干燥和冰川膨胀的快速过渡，这在较慢的响应代理和更远端的档案中可能已经错过。这项研究很重要，因为氢化气候似乎是温度 - 晶体滞后的关键人物。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估来获得支持。