Permeability and pressure measurements in Lesser Antilles submarine slides: Evidence for pressure‐driven slow‐slip failure-猫眼课题宝

DOI：

10.1002/2015jb012061

发表时间：

2015-12

期刊：

Journal of Geophysical Research: Solid Earth

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

M. Hornbach;M. Manga;M. Genecov;R. Valdez;P. Miller;D. Saffer;E. Adelstein;S. Lafuerza;T. Adachi;C. Breitkreuz;M. Jutzeler;A. Friant;O. Ishizuka;S. Morgan;A. Slagle;P. Talling;A. Fraass;S. Watt;N. Stroncik;M. Aljahdali;G. Boudon;A. Fujinawa;R. Hatfield;K. Kataoka;F. Maeno;M. Martínez-Colón;M. McCanta;M. Palmer;A. Stinton;K. Subramanyam;Y. Tamura;B. Villemant;D. Wall-Palmer;Fei Wang

最近的研究假设，一些海底滑坡通过压力驱动的缓慢滑动变形而失败。为了验证这一假设，本研究得出孔隙压力失败和相邻的未失败的深海沉积物整合岩石物理模型，恢复沉积物岩心的物理性质测量，和电缆测井。两个钻探点（U1394和U1399）钻穿了解释的滑动碎屑;第三个钻探点（U1395）钻穿了正常的海洋沉积物。在U1395站点的沉积物中存在近流体静压。相反，在两个站点U1394和U1399的结果表明，在一些沉积物孔隙流体压力升高。我们认为，高孔隙压力在基地的一个海底滑坡存款在现场U1394的结果滑动剪切。高孔隙压力存在于整个站点U1399的大部分，莫尔圆分析表明，只有轻微的变化，在应力状态将触发运动。固结试验和渗透率测量表明，细粒滑屑的渗透率和超固结度中等偏低（~10−16-10−17 m2），这意味着这些沉积物起到了密封作用。三种机制，单独或组合，可能会产生在现场U1399观察到的孔隙流体压力升高：（1）快速沉积，（2）横向流体流动，（3）剪切，导致沉积物收缩，增加孔隙压力。我们的首选假设是这第三种机制，因为它解释了流体压力升高和沉积物超固结，而不需要高沉积速率。我们对地下孔隙压力、钻井数据和区域地震图像的综合分析表明，马提尼克岛近海的边坡破坏可能是一个持续的、类似蠕变的过程，其中小的应力变化引发运动。

Recent studies hypothesize that some submarine slides fail via pressure‐driven slow‐slip deformation. To test this hypothesis, this study derives pore pressures in failed and adjacent unfailed deep marine sediments by integrating rock physics models, physical property measurements on recovered sediment core, and wireline logs. Two drill sites (U1394 and U1399) drilled through interpreted slide debris; a third (U1395) drilled into normal marine sediment. Near‐hydrostatic fluid pressure exists in sediments at site U1395. In contrast, results at both sites U1394 and U1399 indicate elevated pore fluid pressures in some sediment. We suggest that high pore pressure at the base of a submarine slide deposit at site U1394 results from slide shearing. High pore pressure exists throughout much of site U1399, and Mohr circle analysis suggests that only slight changes in the stress regime will trigger motion. Consolidation tests and permeability measurements indicate moderately low (~10−16–10−17 m2) permeability and overconsolidation in fine‐grained slide debris, implying that these sediments act as seals. Three mechanisms, in isolation or in combination, may produce the observed elevated pore fluid pressures at site U1399: (1) rapid sedimentation, (2) lateral fluid flow, and (3) shearing that causes sediments to contract, increasing pore pressure. Our preferred hypothesis is this third mechanism because it explains both elevated fluid pressure and sediment overconsolidation without requiring high sedimentation rates. Our combined analysis of subsurface pore pressures, drilling data, and regional seismic images indicates that slope failure offshore Martinique is perhaps an ongoing, creep‐like process where small stress changes trigger motion.

Permeability and pressure measurements in Lesser Antilles submarine slides: Evidence for pressure‐driven slow‐slip failure

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