Collaborative Research: Investigating Mantle Source Reservoirs and Cretaceous Plate Motions Recorded by Ancient Mid-Pacific Oceanic Rises and Seamount Tracks

合作研究：调查古代中太平洋海隆和海山轨迹记录的地幔源储层和白垩纪板块运动

• 批准号: 2121834
• 负责人: Kevin Konrad
• 金额: $ 38.82万
• 依托单位: University of Nevada Las Vegas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2121834&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Mantle; Source

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Earth’s surface is composed of numerous rigid ‘plates’ that move with the flow of a highly viscous interior mantle. Individual plate movements can be determined if their past motions are compared to a fixed source on Earth, such as so-called “mantle hotspots”. These hotspots are generated by mantle plumes, large thermo-chemical uprisings of material that originate on or near the core-mantle boundary. These upwellings of hot material can produce volcanism on Earth’s surface that remains relatively stationary while plates move over them, generating chains of compositionally distinct volcanoes that are progressively older the further they are from the hotspot. This work, through tracing ages, compositions, and morphologies of several poorly-documented volcanic chains, seeks to better understand the timing and drivers of global scale plate reorganization events that took place in the Mid-Cretaceous (120-80 Ma). The target locations include the Liliuokalani Ridge, Hess Rise and Mid-Pacific Mountains in the Central Pacific region. The team will be able to test whether the features were built by mantle plumes that are currently underlying the Northern French Polynesia region. The combined age and chemistry results will then be used to constrain the timing of a major plate reorganization event at ca. 100 Ma. This project supports three early-career scientists, two PhD, and one MSc student. In addition, the seagoing expedition will include eight undergraduate research participants from the minority serving institutions of University of Nevada, Las Vegas and California State University, Long Beach. The project involves a 31-day seagoing expedition to dredge seamounts, ridges and rises within and near Hess Rise and the Mid-Pacific Mountains. In addition, the team will analyze basalts recovered on NOAA-Ocean Exploration and Research expeditions from Karin Ridge and samples from an upcoming E/V Nautilus expedition to the Liliuokalani Seamounts. Onshore work will include obtaining 40Ar/39Ar age determinations and geochemical tracers (major and trace elements; Sr-Nd-Pb-Hf isotopes) from representative lava flows. These new samples and comprehensive datasets will allow for the testing of the following hypotheses: H1) The Liliuokalani Seamounts and Hess Rise were formed by the Marquesas Mantle Plume. H2) The Pitcairn Mantle Plume is the primary source of the Karin Ridge and Mid-Pacific Mountains. H3) The Mid-Pacific Mountains record the timing and orientation of Cretaceous plate motion changes. H4) The structure of the Mid-Pacific Mountains and Hess Rise are controlled by plume – (distal) ridge interaction through the generation of asthenospheric melt channels. Testing these hypotheses will lead to an improved understanding of mantle plume dynamics and ‘bottom-up’ controls on oceanic geomorphology and large igneous province construction. Furthermore, mapping the long-lived expressions of mantle plumes allows for unparalleled insight into the mantle source reservoirs that feed hotspot volcanism. The combination of geo-chronology, chemistry and morphology will allow for a significantly improved Pacific absolute plate motion model during the Cretaceous Normal Superchron (122-83 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.

该奖项全部或部分由2021年美国救援计划法案（公法117-2）资助。地球表面由许多刚性“板块”组成，这些板块随着高粘性内部地幔的流动而移动。如果将各个板块过去的运动与地球上的一个固定源（如所谓的“地幔热点”）进行比较，就可以确定它们的运动。这些热点是由地幔柱产生的，地幔柱是起源于核幔边界上或附近的物质的大型热化学起义。这些热物质的上升可以在地球表面产生火山活动，当板块在它们上面移动时，这些火山活动保持相对静止，产生组成不同的火山链，这些火山离热点越远，就越古老。这项工作，通过追踪几个记录不多的火山链的年龄，成分和形态，旨在更好地了解发生在白垩纪中期（120-80 Ma）的全球规模板块重组事件的时间和驱动因素。目标地点包括中太平洋区域的Liliuokalani海岭、赫斯海隆和中太平洋山脉。该团队将能够测试这些特征是否是由目前位于法属波利尼西亚北方地区下方的地幔柱建造的。结合年龄和化学的结果，然后将被用来限制一个主要的板块重组事件的时间在约。一百马该项目支持三名早期职业科学家，两名博士和一名硕士生。此外，海上探险将包括来自内华达州大学、拉斯维加斯和加州州立大学、长滩少数民族服务机构的8名本科生研究参与者。 该项目包括一次为期31天的海上考察，挖掘赫斯海隆和中太平洋山脉内及其附近的海山、海岭和海隆。此外，该小组还将分析诺阿海洋勘探和研究考察队从卡林岭回收的玄武岩，以及即将进行的E/V Nautilus考察队到Liliuokalani海山的样本。陆上工作将包括从有代表性的熔岩流中获得40 Ar/39 Ar年龄测定和地球化学示踪剂（主要和微量元素; Sr-Nd-Pb-Hf同位素）。这些新的样本和全面的数据集将允许测试以下假设：H1）Liliuokalani海山和赫斯隆起是由马克萨斯地幔柱形成的。H2）皮特凯恩地幔柱是卡琳海脊和中太平洋山脉的主要来源。H3）中太平洋山脉记录了白垩纪板块运动变化的时间和方向。H4）中太平洋山脉和赫斯海隆的结构是由地幔柱-（远）脊相互作用通过软流层熔融通道的产生控制的。检验这些假设将导致更好地了解地幔柱动力学和“自下而上”的海洋地貌和大火成岩省建设的控制。此外，绘制地幔柱的长寿表现允许对地幔源储层的无与伦比的洞察力，饲料热点火山活动。地质年代学、化学和形态学的结合将使白垩纪正常超时（122-83 Ma）期间的太平洋绝对板块运动模型得到显著改进。该奖项反映了NSF的法定使命，并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，被认为值得支持。