Collaborative Research: Behavior of Boron During Prograde Diagenesis and Metamorphism of Pelagic Sediments from the Nankai Trough

合作研究：南海海槽远洋沉积物的成岩作用和变质作用中硼的行为

• 批准号: 2026692
• 负责人: Demian Saffer
• 金额: $ 19.21万
• 依托单位: University of Texas at Austin
• 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: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2026692&HistoricalAwards=false
• 关键词: Collaborative; Research; Behavior; Boron; During

Subduction zones, where one tectonic plate slides beneath another, are places where water, carbon dioxide and other chemical components are transferred between the Earth’s surface and interior. Some chemical components that enter into subduction zones are released back to the oceans (as water or gas); others contribute to magmas in volcanoes (where they become part of the crust as igneous rocks or are released to the atmosphere as volcanic gases) and still others are transported all the way into the deep interior of the Earth. Understanding how elements and compounds are divided between the surface and the interior of Earth can provide important information about the regulation of carbon dioxide levels in the atmosphere, the concentration of radioactive elements near the surface of the Earth, and the tendency of some volcanoes to erupt violently. This project uses the element boron, which is highly concentrated in seawater and ocean sediments compared to the interior of the Earth, to track the recycling of surface components through subduction zones. If we can measure the amount of boron entering into a subduction zone on the sea floor and how much boron is released by associated volcanoes and into the ocean, then we can calculate how much boron is recycled into the deep Earth. The workplan includes opportunities for intellectual exchange between collaborators in the United States, Italy, and Japan. Students at both the graduate and undergraduate levels will participate in and benefit from the collaborative exchange.Subduction zones are the primary locus for recycling of crustal materials into the Earth’s mantle, with important implications for mantle and continental crustal evolution throughout Earth history. Subducted sediments in particular contribute volatiles, trace elements, and unique isotopic signatures to the oceans, the mantle, and arc magmas. Boron is both highly fluid mobile and isotopically fractionated during thermally-driven desorption and metamorphic dehydration, making it an excellent tracer for both sediment and fluids. In contrast, Rare Earth Elements (HREE) and High Field Strength Elements (HFSE) are generally immobile, making them good tracers of sediment and basalt provenance. By observing the co-variation of B, d11B, and HREE/HFSE concentrations in progressively dehydrated marine clays and subsidiary basalts within a unique sample suite from the Nankai margin, we propose to constrain 1) the initial variability in slab inputs to the trench within a well-constrained segment of a single subduction zone; and 2) the evolution of sediment and released fluid composition through progressive desorption and dehydration prior to entering the sub-arc region. The workplan includes opportunities for intellectual exchange between collaborators in the United States, Italy, and Japan. Students at both the graduate and undergraduate levels will participate in and benefit from the international collaboration.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.

俯冲带在另一个构造板滑落下面的地方是水，二氧化碳和其他化学成分在地球表面和内部之间转移的地方。一些进入俯冲带的化学成分被释放回海洋（作为水或天然气）；其他人则在火山中贡献了岩浆（在火山中成为火成岩的一部分，或者以火山气体的形式释放到大气中），而另一些则一直运输到地球深处。了解元素和化合物如何在地面和地球内部之间分配，可以提供有关大气中二氧化碳水平调节的重要信息，地球表面附近的放射性元件的浓度以及某些火山的趋势猛烈爆发。该项目使用与地球内部相比，高度集中在海水和海洋沉积物中的元素硼，通过俯冲带跟踪表面成分的回收。如果我们可以测量进入海底俯冲带的硼量以及相关火山和海洋释放多少硼，那么我们可以计算多少硼被回收到深地球中。工作场所包括美国，意大利和日本合作者之间的智力交流机会。研究生和本科级别的学生都将参与并受益于协作交流。提包区是将地壳材料回收到地球地幔中的主要基因座，对整个地球历史上的地幔和连续的地壳进化具有重要意义。俯冲的沉积物特别贡献了海洋，地幔和弧岩的挥发物，微量元素和独特的同位素特征。在热驱动的解吸和变质脱水过程中，硼既是流体流动性的高流动性，又是同位素分离，使其成为沉积物和烟道的绝佳示踪剂。相比之下，稀土元素（Hree）和高场强元素（HFSE）通常是不动的，使其成为沉积物和玄武岩的良好示踪剂。通过观察B，D11B和HREE/HFSE浓度的共同变化，逐渐脱水的海洋粘土和子公司底层的逐渐脱水的样品套件中的唯一样本套件中的nankai缘缘，我们建议限制1）1）平板输入的初始变异性，从而在单个单张纸区域内良好地限制的平台段； 2）在进入亚弧形区域之前，通过进行性解吸和脱水释放了沉积物和释放的液体组成。工作场所包括美国，意大利和日本合作者之间的智力交流机会。毕业生和本科生的学生都将参加并从国际合作中受益。该奖项反映了NSF的法定任务，并被认为是使用基金会的知识分子优点和更广泛的影响审查标准来通过评估来获得的支持。