Geochemical and microstructural evidence for interseismic changes in fault zone permeability and strength, A lpine F ault, N ew Z ealand
Geochemical and microstructural evidence for interseismic changes in fault zone permeability and strength, A lpine F ault, N ew Z ealand
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新西兰阿尔卑斯断层断层带渗透性和强度震间变化的地球化学和微观结构证据
DOI：
10.1002/2016gc006588
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Boulton C
中科院分区：
文献类型：
--
作者：
Boulton C
在最后约5 Ma，中央阿尔卑斯断层的斜向右旋运动使石榴石-奥长石相糜棱岩断层岩从1035 km深处被挖出。在折返过程中，变形伴随着流体渗透，在新西兰南岛冈特溪的深断层钻探项目（DFDP-1）钻探期间，在与断层有关的岩石中产生了复杂的岩性变化。岩性，地球化学和矿物学的结果表明，该故障包括高度粉碎碎裂岩和断层泥的核心由一个损伤区，包含碎裂岩，原碎裂岩，断裂糜棱岩界定。断层核蚀变带从主滑动带（PSZ）延伸20-30 m，其特征是原生相变为层状硅酸盐矿物。与不同矿物相相关的蚀变发生在脆性-塑性转变附近（T ≤ 300-400°C，6-10 km深度）和浅层（T = 20-150°C，0-3 km深度）。在断层核蚀变带内，裂缝被方解石和层状硅酸盐的沉淀所封闭。这种封闭性降低了断层正常渗透率，增加了岩体能力，可能促进震间应变积累。
Oblique dextral motion on the central Alpine Fault in the last circa 5 Ma has exhumed garnet‐oligoclase facies mylonitic fault rocks from ∼35 km depth. During exhumation, deformation, accompanied by fluid infiltration, has generated complex lithological variations in fault‐related rocks retrieved during Deep Fault Drilling Project (DFDP‐1) drilling at Gaunt Creek, South Island, New Zealand. Lithological, geochemical, and mineralogical results reveal that the fault comprises a core of highly comminuted cataclasites and fault gouges bounded by a damage zone containing cataclasites, protocataclasites, and fractured mylonites. The fault core‐alteration zone extends ∼20–30 m from the principal slip zone (PSZ) and is characterized by alteration of primary phases to phyllosilicate minerals. Alteration associated with distinct mineral phases occurred proximal the brittle‐to‐plastic transition (T ≤ 300–400°C, 6–10 km depth) and at shallow depths (T = 20–150°C, 0–3 km depth). Within the fault core‐alteration zone, fractures have been sealed by precipitation of calcite and phyllosilicates. This sealing has decreased fault normal permeability and increased rock mass competency, potentially promoting interseismic strain buildup.