Large-scale electrical resistivity and bulk porosity of the oceanic crust, Deep Sea Drilling Project Hole 504B, Costa Rica Rift.
Large-scale electrical resistivity and bulk porosity of the oceanic crust, Deep Sea Drilling Project Hole 504B, Costa Rica Rift.
复制标题
洋壳的大尺度电阻率和大孔隙度，深海钻探项目孔 504B，哥斯达黎加裂谷。
DOI：
10.2973/dsdp.proc.83.124.1985
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发表时间：
1985
影响因子：
--
通讯作者：
K. Becker
中科院分区：
文献类型：
--
作者：
K. Becker
在第83航次期间，在504 B孔的大洋地壳第2层超过1公里的范围内成功地进行了长距离直流电阻率实验。该实验对垂直和径向平均尺度约为5至50米的原地地壳活动性作出了反应。在约600米的枕状熔岩中，表观地壳电阻率约为10欧姆-米，在下面的岩脉中急剧增加到近500欧姆-米。通过将阿尔奇定律应用于表观孔隙率来近似估算整体地壳孔隙率。表观孔隙度从枕状熔岩的约10%急剧下降到岩脉的约2%，结果表明有三个孔隙层，似乎对应于地震层2A、2B和2C。回收玄武岩样品的表观体积孔隙度与船上孔隙度测量值的比较表明，层2A和2B具有显着的开放裂缝孔隙度，而层2C的岩脉具有非常小的裂缝孔隙度。视电阻率随深度的急剧增加和视总孔隙度的数量级降低与504 B孔中测量的地壳总渗透率随深度的急剧降低高度一致。
A long-spaced, DC electrical resistivity experiment was run successfully during Leg 83, throughout over 1 km of Layer 2 of the oceanic crust at Hole 504B. This experiment responds to in situ crustal resistivities over vertical and radial averaging scales of about 5 to 50 m. Apparent crustal resistivities are about 10 ohm-m in about 600 m of pillow lavas, sharply increasing to nearly 500 ohm-m in the underlying dikes. Bulk crustal porosities were approximated by applying Archie's Law to the apparent resistivities. Apparent porosities decrease sharply from about 10% in the pillow lavas to about 2% in the dikes, and the results indicate three porosity layers which seem to correspond to seismic Layers 2A, 2B, and 2C. Comparison of the apparent bulk porosities to shipboard porosity measurements on recovered basalt samples suggests that Layers 2A and 2B have significant open fracture porosity, whereas the dikes of Layer 2C have very little fracture porosity. The sharp increase with depth of apparent resistivity and the order-of-magnitude decrease in apparent bulk porosity are highly consistent with the steep reduction with depth of bulk crustal permeability measured in Hole 504B.