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中压力、流体化学和水文的长期连续监测

• 批准号: 0118478
• 负责人: Miriam Kastner
• 金额: $ 59.91万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 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=0118478&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.

该项目将使用在ODP203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、流体化学和水文学。现场计划将1)在沿俯冲带变形前沿的横断面上的3个软木钻孔中部署压力计和数据记录仪、渗透采样器和渗透流量计，2)取回渗透采样器、数据记录仪中存储的数据，并与潜水器Alvin一起部署新的渗透采样器和压力计。渗透采样器中储存的流体将在三个不同的水文地质系统中以每周分辨率提供在现场条件下收集的流体状况的连续1.3年记录。第一个流动系统是进入科科斯板块的上洋壳，第二个流动系统是深源流体沿滑脱的返回，第三个流动系统是在压实脱水驱动的逆冲沉积段。通过记录这些水文地质系统的性质，将有可能更好地了解汇聚边缘的流体流动对下行板块的浅层热结构和流体含量的影响、俯冲带界面的物理性质、变形方式和元素向海洋的输送。