Collaborative Research: Long Term Continuous Monitoring of Pressure, Fluid Chemistry, and Hydrology in Instrumented Boreholes at the Costa Rica Subduction Zone

合作研究：哥斯达黎加俯冲带仪器钻孔的压力、流体化学和水文学的长期连续监测

• 批准号: 0118377
• 负责人: Douglas Wiens
• 金额: $ 4.79万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-10-01 至 2006-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0118377&HistoricalAwards=false
• 关键词: Collaborative; Research; Long; Term; Continuous

This project will continuously monitor the pressure, fluid chemistry, and hydrology in two instrumented boreholes at the Costa Rica subduction zone, using long-term observatories (CORK and ACORK) installed during ODP Leg 203. The field program will 1) deploy pressure gauges and data loggers, OsmoSamplers, and osmotic flow meters in 3 CORKed boreholes along a transect across the deformation front of the subduction zone and 2) retrieve the OsmoSamplers, data stored in the data loggers and deploying new OsmoSamplers and pressure gauges, with the submersible Alvin. The fluid stored in the OsmoSamplers will provide a continuous 1.3 year record of fluid conditions collected at in situ conditions at weekly resolution, in three distinct hydrogeologic systems. The first flow system is the upper oceanic crust of the incoming Cocos Plate, the second is the return of a deeply sourced fluid along the decollement and the third is in the underthrust sediment section driven by compaction dewatering. By documenting the nature of these hydrogeologic systems it will be possible to better understand the effects of fluid flow at convergent margins on the shallow thermal structure and fluid content of the downgoing plate, the physical properties of the subduction zone interface, deformation style and transport of elements to the oceans.

该项目将使用 ODP 第 203 段期间安装的长期观测站（CORK 和 ACORK），持续监测哥斯达黎加俯冲带两个仪器钻孔的压力、流体化学和水文。该现场计划将 1) 在沿着俯冲带变形前部横断面的 3 个软木塞钻孔中部署压力计和数据记录仪、OsmoSampler 和渗透流量计，以及 2) 使用潜水器 Alvin 检索 OsmoSamplers、存储在数据记录器中的数据并部署新的 OsmoSamplers 和压力表。 OsmoSampler 中存储的流体将提供在三个不同的水文地质系统中按周分辨率在原位条件下收集的流体状况的连续 1.3 年记录。第一个流动系统是传入科科斯板块的上洋壳，第二个是深层流体沿着滑脱的返回，第三个是在压实脱水驱动的逆冲沉积部分中。 通过记录这些水文地质系统的性质，将有可能更好地了解会聚边缘的流体流动对下降板块的浅层热结构和流体含量、俯冲带界面的物理性质、变形类型和元素向海洋的输送的影响。