Three-dimensional characterization of a crustal-scale fault zone: The Pusteria and Sprechenstein fault system (Eastern Alps)
Three-dimensional characterization of a crustal-scale fault zone: The Pusteria and Sprechenstein fault system (Eastern Alps)
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DOI：
10.1016/j.jsg.2010.06.003
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发表时间：
2010-12-01
影响因子：
3.1
通讯作者：
Menegon, Luca
中科院分区：
文献类型：
--
作者：
Bistacchi, Andrea;Massironi, Matteo;Menegon, Luca
断层带的表征和表示对于断层和地震力学的研究是至关重要的，因为它们的流变学和几何学复杂性控制着地震/抗震行为和深部流体循环。我们提出了一个断层系统的三维地质模型，通过整合钻孔和地表结构数据，这使我们能够弥合露头规模的描述和大规模的地球物理模型之间的差距差距。该模型集成了（i）断层几何形状和拓扑结构，（ii）断层岩石分布，以及（iii）km尺度的损伤区断裂特征。右旋反向Pusteria和Sprechenstein-Mules断层（意大利东阿尔卑斯山）提供了一个机会，研究断层岩石和损害分布作为主岩岩性和组构的函数，以及断层的几何形状。一阶控制施加的组成的原岩（quartzo-feld-spathic与层状硅酸盐丰富）和/或存在的继承性各向异性织物（大量与叶状），导致在一个显着的不对称的损害区。有趣的是，一些原岩普遍存在的叶理现象可以解释这种不对称性和其中一个断层的相对薄弱。几何因素的重要性突出时，损伤区厚度增加五倍，接近公里级收缩慢跑。另一方面，断层核内存在的断层岩类型与损伤强度没有直接关系。此外，沿着沿着平面断层段的损伤区的厚度似乎并不随位移而无限增长，这可能是从某些比例定律中设想的。我们认为这两个观测结果都反映了这些大位移断层的成熟度。(C)2010爱思唯尔有限公司版权所有。
The characterization and representation of fault zones is of paramount importance for studies of fault and earthquake mechanics, since their rheological and geometric complexity controls seismic/aseismic behaviour and fluid circulation at depth. We present a 3D geological model of a fault system, created by integrating borehole and surface structural data, which allows us to bridge the gap between outcrop-scale descriptions and large-scale geophysical models. The model integrates (i) fault geometry and topology, (ii) fault-rock distribution, and (iii) characterization of fracturing in damage zones at the km scale. The dextral-reverse Pusteria and Sprechenstein-Mules Faults (Italian Eastern Alps) provide an opportunity to study fault rocks and damage distribution as a function of host-rock lithology and fabric, and of fault geometry. A first-order control is exerted by the composition of protoliths (quartzo-feld-spathic vs. phyllosilicate-rich) and/or by the presence of an inherited anisotropic fabric (massive vs. foliated), resulting in a marked asymmetry of damage zones. Interestingly, the pervasive foliation typical of some protoliths may explain both this asymmetry and the relative weakness of one of the faults. The importance of geometrical factors is highlighted when the damage zone thickness increases five times in proximity to a km-scale contractional jog. On the other hand, the type of fault rock present within the fault core does not show a direct relationship with damage intensity. In addition, the thickness of damage zones along planar fault segments does not appear to grow indefinitely with displacement, as might be envisaged from some scaling laws. We interpret both of these observations as reflecting the maturity of these large-displacement faults. (C) 2010 Elsevier Ltd. All rights reserved.