Petrophysical, Geochemical, and Hydrological Evidence for Extensive Fracture‐Mediated Fluid and Heat Transport in the Alpine Fault's Hanging‐Wall Damage Zone-猫眼课题宝

DOI：

10.1002/2017gc007202

发表时间：

2017-12

期刊：

Geochemistry

影响因子：

3.7

通讯作者：

中科院分区：

地球科学3区

文献类型：

作者：

John Townend;R. Sutherland;V. Toy;M. Doan;B. Célérier;C. Massiot;Jamie Coussens;T. Jeppson;Lucie Janku‐Capova;L. Remaud;P. Upton;D. Schmitt;P. Pezard;J. Williams;M. Allen;L. Baratin;N. Barth;Leeza Becroft;C. Boese;C. Boulton;N. Broderick;B. Carpenter;C. Chamberlain;A. Cooper;A. Coutts;S. Cox;L. Craw;J. Eccles;D. Faulkner;J. Grieve;J. Grochowski;Anton K. Gulley;A. Hartog;G. Henry;J. Howarth;K. Jacobs;N. Kato;S. Keys;Martina Kirilova;Y. Kometani;R. Langridge;Weiren Lin;T. Little;Adrienn Lukács;D. Mallyon;E. Mariani;L. Mathewson;B. Melosh;C. Menzies;Joseph M. Moore;L. Morales;H. Mori;A. Niemeijer;O. Nishikawa;O. Nitsch;J. Paris;D. Prior;K. Sauer;M. Savage;A. Schleicher;N. Shigematsu;S. taylor-offord;D. Teagle;H. Tobin;R. Valdez;K. Weaver;T. Wiersberg;M. Zimmer

断层岩组合反映了地壳不同位置不同时空尺度上变形、应力、温度、流体和化学状态之间的相互作用。在这里，我们解释了深断层钻探项目（DFDP-2）第二阶段在阿尔卑斯断层上盘进行的测量。我们提出了广泛的压裂和高上盘水力传导率（10 − 9至10 − 7 m/s，对应于10 − 16至10 − 14 m2的渗透率）的观测证据，从断层的主滑动带延伸数百米。泥浆漏失、气体化学异常和岩石物理数据表明，由钻孔覆盖的一组裂缝能够在小时的时间尺度上传输几立方米的流体量。DFDP-2观测和其他数据表明，上盘断层带的水文地质活动部分在地壳最上层有几公里宽。这一发现与地震破裂和断层外破坏的数值模型一致。我们的结论是，机械和水文地质活动的阿尔卑斯山断层的一部分是一个更动态和广泛的功能比通常所描述的模型的基础上挖掘断层。我们建议，水文地质活动区的阿尔卑斯山断层和其他大型活动断层在高地形起伏的地区，可以细分为一个内部区域，其中损害主要是由地震破裂过程和外部区域，其中损害反映同震震动，应变积累和释放的地震间的时间尺度上，继承破裂有关的折返。

Fault rock assemblages reflect interaction between deformation, stress, temperature, fluid, and chemical regimes on distinct spatial and temporal scales at various positions in the crust. Here we interpret measurements made in the hanging‐wall of the Alpine Fault during the second stage of the Deep Fault Drilling Project (DFDP‐2). We present observational evidence for extensive fracturing and high hanging‐wall hydraulic conductivity (∼10−9 to 10−7 m/s, corresponding to permeability of ∼10−16 to 10−14 m2) extending several hundred meters from the fault's principal slip zone. Mud losses, gas chemistry anomalies, and petrophysical data indicate that a subset of fractures intersected by the borehole are capable of transmitting fluid volumes of several cubic meters on time scales of hours. DFDP‐2 observations and other data suggest that this hydrogeologically active portion of the fault zone in the hanging‐wall is several kilometers wide in the uppermost crust. This finding is consistent with numerical models of earthquake rupture and off‐fault damage. We conclude that the mechanically and hydrogeologically active part of the Alpine Fault is a more dynamic and extensive feature than commonly described in models based on exhumed faults. We propose that the hydrogeologically active damage zone of the Alpine Fault and other large active faults in areas of high topographic relief can be subdivided into an inner zone in which damage is controlled principally by earthquake rupture processes and an outer zone in which damage reflects coseismic shaking, strain accumulation and release on interseismic timescales, and inherited fracturing related to exhumation.

Petrophysical, Geochemical, and Hydrological Evidence for Extensive Fracture‐Mediated Fluid and Heat Transport in the Alpine Fault's Hanging‐Wall Damage Zone

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