Hydrogeology of the Juan de Fuca Ridge - implications from downhole logging and petrophysical core data

综合海洋钻探计划Leg 300计划通过深钻海洋地壳、孔间实验和长期观察来调查Juan de Fuca Ridge东侧的水文地质情况。本研究计划的目标是利用钻孔的地球物理测量（测井数据）和Leg 300钻孔的岩心样本来研究(1)Juan de Fuca Ridge东侧的水文地质与基底结构之间的关系以及(2)海水穿过地壳的循环对岩石物理性质的影响。来自测井数据的连续物理信息将用于重建钻孔的火山构造，以获得连续的岩性剖面，该剖面不会因预期的高岩心损失而受到间隙的影响。连续重建的剖面将用于绘制和量化发生的熔岩形态。并确定可能的含水层层及其与钻探地点喷发历史的关系。将Leg 300钻孔的岩石物理资料与其他已存在的海洋地壳钻孔的岩石物理资料进行比较，将揭示海洋地壳热液蚀变和老化对地壳物理性质的影响。

Integrated Ocean Drilling Program Leg 300 plans investigate the hydrogeological situation at the eastern flank of the Juan de Fuca Ridge by deep drilling into the oceanic crust, crosshole experiments, and long-term observations. The objectives of this research proposal are to use geophysical measurements from boreholes (well-logging data) and from core samples from Leg 300 boreholes to study (1) the relation between hydrogeology and the basement architecture at the eastern flank of Juan de Fuca Ridge and (2) the effect of circulation of seawater through the crust on the physical properties of the rocks. The continuous physical information from the well-logging data will be used to reconstruct the volcanic architecture of the drill holes in order to obtain continuous lithological profiles that are not biased by gaps due to an expected high core loss. The continuous reconstructed profiles will be used to map and quantify the occurring lava morphologies... and to identify possible aquifer horizons and their relation to the eruption history at the drill site. Comparison of petrophysical data from the Leg 300 boreholes and other already existing boreholes into oceanic crust will reveal the effect of hydrothermal alteration and ageing of oceanic crust con the physical properties of the crust.