Collaborative Research: Characterization of Subduction Channel Processes - Borehole Sampling at Active Serpentinite Mud Volcanoes on the Mariana Forearc

合作研究：俯冲通道过程的表征 - 马里亚纳弧前活跃蛇纹岩泥火山的钻孔采样

• 批准号: 1921361
• 负责人: Jeffrey Seewald
• 金额: $ 32.53万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1921361&HistoricalAwards=false
• 关键词: Collaborative; Research; Characterization; Subduction; Channel

The Mariana Trench is the deepest location on Earth, resulting from the subduction of the Pacific Plate under the Philippine Plate. Fluids that were trapped in the pores and minerals of the Pacific Plate are liberated during this subduction. These fluids react with rock in the overriding Philippine Plate to produce a slurry of mud and fluids that are very alkaline (with a pH up to 12.5, more alkaline than Clorox), yet support microbial life that thrives in such extreme environments. The discharge produces the largest mud volcanoes on Earth, some spanning 50 km in diameter and several kilometers in height. Probing the mud volcanoes by sampling fluids from boreholes drilling into them, provides the means to examine processes that occur at depth during subduction. The subduction zone environment is the epicenter for most large earthquakes on Earth, and the fluids that flow through subduction zones can be connected with that earthquake generation. Moreover, the reactions that occur to produce the fluids provide energy that can support a wide variety of microbes, a subseafloor biosphere that is present throughout what has been referred to broadly as a "deep crustal aquifer".The research team proposes to the sample fluids and dissolved gases from this ascending slurry in three mud volcanoes that tap different pressure (depths ranging from 10 to 20 km) and temperature conditions at depth. These ascending fluids discharge from scientific boreholes that were emplaced during International Ocean Discovery Program (IODP) Expedition 366. Prior to sampling these fluids, CORK-Lite instruments will be deployed to enable sampling operations. This infrastructure will also provide for a range of potential experimentation and monitoring efforts that can be used in the future. Specifically, the project will: (i) design, fabricate, and deploy CORK-Lites, (ii) sample discharging fluids with gas-tight and large volume sampling systems, (iii) analyze collected fluids for a range of solutes, dissolved gases, and isotopes, and (iv) measure borehole pressure and fluid discharge rates. The CORK-Lites will be sealed at the end of the field program for future experimentation and monitoring efforts. Results from this effort will test a model of abiotic methane formation, constrain the extent of serpentinization during the initial stages of subduction, set limits on potential microbial metabolic capabilities, and resolve water-rock reactions and solute sources.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.

玛丽安娜（Mariana）的沟渠是地球上最深的位置，这是由于菲律宾板块下太平洋板块的俯冲而导致的。在此俯冲期间，将被困在太平洋板块的孔和矿物质中的液体被释放。这些流体与岩石在菲律宾板块中的岩石反应，以产生非常碱性的泥浆和液体（pH值为12.5，碱性比Clorox高），但支持在这种极端环境中繁荣发展的微生物生命。排放产生地球上最大的泥土火山，有些直径为50公里，高度几公里。通过对钻孔进行采样液体来探测泥石火山，提供了检查俯冲过程中深度发生的过程的手段。俯冲带环境是地球上大多数大地震的震中，流过俯冲带的流体可以与地震产生相连。此外，产生流体的反应提供了能够支持多种微生物的能量，这是一种在整个被称为“深层甲壳含水层”中存在的子膜生物圈。并从三个泥石火山中溶解了这种上升的泥浆中的气体，这些泥石火山敲击了不同的压力（深度为10至20 km）和深度的温度条件。这些上升的液体从国际海洋发现计划（IODP）探险366期间放置的科学钻孔排出。在对这些液体进行采样之前，将部署软木仪仪器以启用采样操作。这种基础设施还将提供一系列潜在的实验和监视工作，这些实验和监视工作将来可以使用。具体而言，该项目将：（i）设计，制造和部署软木塞，（ii）用气密和大容量采样系统排放液体的样品，（iii）分析收集的液体，以供一系列溶质，溶解的气体，溶解的气体，溶解的气体，，和同位素，以及（iv）测量井眼压力和流体排放速率。在现场计划的末尾将密封软木塞，以进行未来的实验和监测工作。这项工作的结果将测试一个非生物甲烷形成的模型，限制俯冲阶段期间蛇形化的程度，对潜在的微生物代谢能力设置限制，并解决水摇滚反应和溶质源。此奖项反映了NSF的法定任务和法定任务。使用基金会的知识分子优点和更广泛的审查标准，通过评估被认为值得支持。