Collaborative Research: Long Term Continuous Sampling of Fluids in Instrumented Boreholes on the Eastern Flank of the Juan de Fuca Ridge

推荐的合作项目包括在1999年回收四个渗透采样器，这些渗透采样器是JOIDES Resolution在1996年在ODP Leg 168期间在Juan de Fuca Ridge东侧钻探的孔中部署的。此外，将在钻孔底部收集升体积样品，并进行钻孔流体温度测量。这些孔是用ODP软木塞密封的，它允许仪器检索和数据读取通过端口和接口到仪器的顶部表面。打捞作业需要使用为期5天的Alvin潜水器和电缆再入工具（WRT），该工具的进一步开发将由本提案提供资金。回收后的OsmoSampler样品代表了3年井内流体组成的连续记录，将对Na、K、Li、Rb、Sr、Si、B、Ba、Mn、Fe、Br、F、NH4、NO3、PO4、SO4和稀土元素进行大范围的主要、次要和微量元素分析。它们还将被分析广泛的同位素组成，包括氢、氧、锶、硼、锂、氯和铍。大量样品将被分析氚（以检查井内流体是否受到周围海水的污染）、Ar、Xe、CO2和CH4浓度，以及He同位素组成，如果有足够的CO2和CH4存在，则分析C同位素。回收后，将对软木塞上的孔进行封堵，并在一个孔（现场1026）安装一个新的仪器“帽”，用于评估当前超压基底流体正在排放的当地水文变化的化学反应。该项目将是迄今为止获得在海洋地壳内循环的实际地层流体的最佳机会。这些样品将允许对结晶海洋地壳随着年龄的增长而发生的蚀变过程进行基本检查，为测试海洋基底和海水之间的化学通量模型提供一种手段，这对了解两者的组成至关重要。* * *

OCE 98-11557 Kastner OCE 98-12121 Wheat The recommended Collaborative project involves retrieval in 1999 of four OsmoSamplers deployed by the JOIDES Resolution in holes drilled in 1996 on the eastern flank of the Juan de Fuca Ridge during ODP Leg 168. In addition, liter-volume samples will be collected at the base of the boreholes, and borehole fluid temperature measurements will also be made. These holes were sealed with the ODP CORKs, which allow instrument retrieval and data readout through ports and interfaces to instrument strings on their top surface. Retrieval involves five days of use of the Alvin submersible in association with a Wireline Re-entry Tool (WRT), further development of which will be funded by this proposal. After retrieval, the OsmoSampler samples, representing a continuous record of borehole fluid composition for three years, will be analyzed for a large range of major, minor and trace elements, including Na, K, Li, Rb, Sr, Si, B, Ba, Mn, Fe, Br, F, NH4, NO3, PO4, SO4, and the rare earth elements. They will also be analyzed for a wide range of isotopic compositions, including those of H, O, Sr, B, Li, Cl, and Be. The large volume samples will be analyzed for tritium (to check for borehole fluid contamination with ambient seawater), Ar, Xe, CO2, and CH4 concentrations, for He isotopic composition, and for C isotopes if enough CO2 and CH4 are present. The holes in the CORK will be capped after retrieval, with emplacement of a new instrument "cap" at one hole (Site 1026) for evaluation of the chemical response to local hydrographic changes where over-pressured basement fluids are currently venting. This project will represent the best opportunity to date to obtain actual formation fluids that are circulating within the oceanic crust. These samples will allow a fundamental examination of alteration processes occurring within the crystalline oceanic crust as it ages, providing a means for testing models of chemical flux between oceanic basement and seawater essential t owards understanding the composition of both. ***