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.

该奖项的全部或部分资金根据《2021 年美国救援计划法案》（公法 117-2）提供。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。如果将它们过去的运动与地球上的固定源进行比较，例如所谓的“地幔热点”，这些热点是由地幔羽流、大型热化学物质产生的。起源于地核-地幔边界或其附近的物质的上升可以在地球表面产生火山活动，当板块在其上移动时，火山活动保持相对静止，从而产生成分不同的火山链，距离越远，火山链的年龄就越大。这项工作通过追踪几个记录很少的火山链的年龄、成分和形态，旨在更好地了解发生在该地区的全球规模板块重组事件的时间和驱动因素。目标地点包括白垩纪中期（120-80 Ma），该团队将能够测试这些特征是否是由目前下方的地幔柱形成的。法属波利尼西亚北部地区的综合年龄和化学结果将用于限制大约 100 Ma 的主要板块重组事件的时间。此外，此次航海考察还将包括来自内华达大学拉斯维加斯分校和加州州立大学长滩分校的少数族裔服务机构的八名本科生研究人员。疏浚赫斯隆起和中太平洋山脉内部及其附近的海山、山脊和海隆。此外，该团队还将分析在美国国家海洋和大气管理局海洋勘探和研究探险队中从卡林海脊回收的玄武岩和来自卡林海脊的样本。即将进行的 E/V Nautilus 探险队对 Liliuokalani 海山的陆上工作将包括从这些新样本和综合数据集中获取 40Ar/39Ar 年龄测定和地球化学示踪剂（主要元素和微量元素；Sr-Nd-Pb-Hf 同位素）。将允许检验以下假设： H1) Liliuokalani 海山和赫斯隆起是由马克萨斯地幔形成的H2) 皮特凯恩地幔柱是卡林海岭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。和赫斯隆起是通过软流圈融化通道的产生而受到羽流-（远端）山脊相互作用的控制，检验这些假设将有助于加深对地幔的了解。此外，绘制地幔柱的长期表现可以对热点火山作用的地幔源储层进行无与伦比的洞察。化学和形态学将允许显着改进白垩纪正常超纪元（122-83 Ma）期间的太平洋绝对板块运动模型。该奖项是 NSF 的法定使命，并已被通过使用基金会的智力优点和更广泛的影响审查标准进行评估，认为值得支持。