Collaborative Proposal: Miocene Climate Extremes: A Ross Sea Perspective from IODP Expedition 374 and DSDP Leg 28 Marine Sediments

合作提案：中新世极端气候：IODP 374 号探险队和 DSDP 第 28 段海洋沉积物的罗斯海视角

• 批准号: 1947657
• 负责人: Justin Dodd
• 金额: $ 12.56万
• 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: 2020-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1947657&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Miocene; Climate; Extremes

Nontechnical abstractPresently, Antarctica’s glaciers are melting as Earth’s atmosphere and the Southern Ocean warm. Not much is known about how Antarctica’s ice sheets might respond to ongoing and future warming, but such knowledge is important because Antarctica’s ice sheets might raise global sea levels significantly with continued melting. Over time, mud accumulates on the sea floor around Antarctica that is composed of the skeletons and debris of microscopic marine organisms and sediment from the adjacent continent. As this mud is deposited, it creates a record of past environmental and ecological changes, including ocean depth, glacier advance and retreat, ocean temperature, ocean circulation, marine ecosystems, ocean chemistry, and continental weathering. Scientists interested in understanding how Antarctica’s glaciers and ice sheets might respond to ongoing warming can use a variety of physical, biological, and chemical analyses of these mud archives to determine how long ago the mud was deposited and how the ice sheets, oceans, and marine ecosystems responded during intervals in the past when Earth’s climate was warmer. In this project, researchers from the University of South Florida, University of Massachusetts, and Northern Illinois University will reconstruct the depth, ocean temperature, weathering and nutrient input, and marine ecosystems in the central Ross Sea from ~17 to 13 million years ago, when the warm Miocene Climate Optimum transitioned to a cooler interval with more extensive ice sheets. Record will be generated from new sediments recovered during the International Ocean Discovery Program (IODP) Expedition 374 and legacy sequences recovered in the 1970’s during the Deep Sea Drilling Program. Results will be integrated into ice sheet and climate models to improve the accuracy of predictions. The research provides experience for three graduate students and seven undergraduate students via a multi-institutional REU program focused on increasing diversity in Antarctic Earth Sciences. Technical AbstractDeep-sea sediments reveal that the Miocene Climatic Optimum (MCO) was the warmest climate interval of the last ~20 Ma, was associated with global carbon cycle changes and ice growth, and immediately preceded the Middle Miocene Climate Transition (MMCT; ~14 Ma), one of three major intervals of Antarctic ice expansion and global cooling. Ice-proximal studies are required to assess: where and when ice grew, ice sheet extent, continental shelf geometry, high-latitude heat and moisture supply, oceanic and/or atmospheric temperature influence on ice dynamics, regional sea ice extent, meltwater input, and regions of bottom water formation. Existing studies indicate that ice expanded beyond the Transantarctic Mountains and onto the prograding Ross Sea continental shelf multiple times between ~17 and 13.5 Ma. However, these records are either too ice-proximal/terrestrial to adequately assess ocean-ice interactions or under-studied. To address this data gap, this work will: 1) generate micropaleontologic and geochemical records of oceanic and atmospheric temperature, water depth, ocean circulation, and paleoproductivity from existing Ross Sea marine sedimentary sequences, and 2) use these proxy records to test the hypothesis that dynamic glacial expansion in the Ross Sea sector during the MCO was driven by heat and moisture transport to the high latitudes during an interval of enhanced climate sensitivity. Downcore geochemical and micropaleontologic studies will focus on an expanded (120 m/my) early to middle Miocene (~17-16 Ma) diatom-bearing/rich mudstone/diatomite unit from IODP Site U1521, drilled on the Ross Sea continental shelf. A hiatus (~16-14.6 Ma) suggests ice expansion during the MCO, followed by diamictite to mudstone unit indicative of slight retreat (14.6 -14 Ma) immediately preceding the MMCT. Data from Site U1521 will be integrated with foraminiferal geochemical and micropaleontologic data from DSDP Leg 28 (1972/73) and RISP J-9 (1978-79) to develop a MCO to late Miocene regional view of ocean-ice sheet interactions using legacy core material previously processed for foraminifera. This integrated record will: 1) document the timing and extent of glacial advances and retreats across the prograding Ross Sea shelf during the middle and late Miocene, 2) provide orbital-scale paleotemperature reconstructions (TEX86, Mg/Ca, δ18O, MBT/CBT) to establish atmosphere-ocean-ice interactions during an extreme high-latitude warm interval, and 3) provide orbital-scale nutrient/paleoproductivity, ocean circulation, and paleoenvironmental data required to assess climate feedbacks associated with Miocene Antarctic ice sheet and global climate system development.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.

非技术性抽象的是，南极的辉煌在地球的大气层和南大洋温暖时正在融化。对于南极的冰盖可能如何应对持续的变暖和未来的变暖，这很重要，因为南极的冰盖可能会随着持续的融化而大大提高全球海平面。随着时间的流逝，泥浆积聚在南极周围的海底上，该泥土由微观海洋生物的骨骼和碎屑和邻近大陆的沉积物组成。随着这种泥浆的沉积，它创造了过去的环境和生态变化的记录，包括海洋深度，冰川前进和撤退，海洋温度，海洋循环，海洋生态系统，海洋化学和连续风化。有兴趣了解南极的冰川和冰盖如何应对持续变暖的科学家可以使用这些泥浆档案的各种物理，生物学和化学分析来确定泥浆被存放了多久，以及在地球气候变暖时，在过去的间隔中，冰块，海洋和海洋生态系统如何做出反应。在该项目中，南佛罗里达大学，马萨诸塞大学和北伊利诺伊大学的研究人员将重建中部罗斯海中部的深度，海洋温度，风化和营养输入，并在罗斯海中部的海洋生态系统，从大约17到1700万年前，当时，在温暖的海洋代行的气候最佳过渡到更广泛的冰期冰层时。在国际海洋发现计划（IODP）Expedition 374中回收的新沉积物以及1970年代在深海钻探计划期间回收的遗产序列将产生记录。结果将集成到冰盖和气候模型中，以提高预测的准确性。该研究通过一项旨在增加南极地球科学多样性的多机构的REU计划为三名研究生和七名本科生提供了经验。技术摘要Deeep-Sea沉积物表明，中新世气候最佳（MCO）是最后一个〜20 MA的最温暖的气候间隔，与全球碳循环变化和冰的增长有关，并在中新世中期气候过渡（MMCT; 〜14 MA）之前，是内聚冰膨胀和全球凉爽的三个主要间隔之一。需要进行冰氧化研究来评估：冰块生长的何时何地，冰盖范围，连续的架子几何形状，高纬度热和水分供应，海洋和/或大气温度对冰动力学的影响，区域海冰范围，融化水域输入以及底部水形成区域。现有的研究表明，冰扩展到跨北极山脉，并在〜17至13.5 Ma之间多次扩展到编程Ross Sea Sea Continenth货架。但是，这些记录要么太过冰/陆地，无法充分评估海冰相互作用或研究不足。为了解决这一数据差距，这项工作将：1）产生微生产和地球化学记录，记录海洋和大气温度，水深，海洋循环以及现有的Ross Sea Sea船舶沉积序列的古生物学效率，以及2）使用这些先进记录，以测试MCO在MCO在MCO中进行的动态扩张，并在MCO驱动过程中进行散热的过程，并进行潮流，并在MCO驱动过程中进行了潮流，并进行了潮流。增强气候灵敏度。下侧地球化学和微生物生产研究将集中于中新世早期至中期（〜17-16 mA）含硅藻的硅藻/富含硅藻的含IODP U1521的硅藻含量/富米石，该单元在Ross Sea Conatornental架子上钻了。一个中断（〜16-14.6 Ma）表明在MCO期间冰膨胀，然后是二镁石至泥岩单位，指示紧接MMCT之前的轻微撤退（14.6 -14 mA）。来自网站U1521的数据将与DSDP Leg 28（1972/73）和RISP J-9（1978-79）的有孔虫地球化学和微生物气直生产数据集成，以使用先前处理过多的ForamInInifera的遗留核心材料来开发MCO至中新世的MCO到后期的中新世区域视图。这一集成记录将：1）记录中新世中期和晚期在编程Ross Sea架上冰川进步和撤退的时间和程度营养/古生物生产力，海洋循环和古环境数据，以评估与中新世南极冰盖和全球气候系统发展相关的气候反馈。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的影响审查审查标准来通过评估来通过评估来获得支持的。