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

OCE 98-11557 Kastner OCE 98-12121小麦建议的合作项目包括在1999年回收JOIDES决议部署的四个渗透采样器，这些采样器是1996年在ODP168航段期间在胡安德富卡山脊东侧钻孔中部署的。此外，还将在井底采集升体积样品，并进行井筒流体温度测量。这些孔是用ODP软木塞密封的，软木塞允许通过端口和接口将仪器检索和数据读出到其顶部表面的仪器弦上。打捞工作涉及使用阿尔文潜水器五天，并配合有线再入工具(WRT)，该工具的进一步开发将由这项提议提供资金。三年来连续记录井眼流体成分的渗透率采样器样品将被分析，包括Na，K，Li，Rb，Sr，Si，B，Ba，Mn，Fe，Br，F，NH4，NO3，PO4，SO4和稀土元素等大范围的主、次和微量元素。还将对它们进行广泛的同位素组成分析，包括H、O、Sr、B、Li、Cl和Be的同位素组成。大量样品将被分析氚(以检查井下流体与周围海水的污染)、Ar、Xe、CO2和CH4浓度，He同位素组成，如果存在足够的CO2和CH4，还将分析C同位素。回收后将封堵软木塞上的孔洞，在一个孔洞(1026号场地)安放一个新仪器“盖子”，以评估对当地水文变化的化学响应，在那里超压的基底流体目前正在泄漏。该项目将是迄今为止获取洋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洋壳内随着年龄的变化而发生的变化过程进行基本检查，为测试海洋基底和海水之间的化学通量模型提供了一种手段，这对于了解两者的组成是必不可少的。***

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. ***