Seismic imaging of a megathrust splay fault in the North Chilean subduction zone (Central Andes)
Seismic imaging of a megathrust splay fault in the North Chilean subduction zone (Central Andes)
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智利北部俯冲带（安第斯山脉中部）巨型逆冲张开断层的地震成像
DOI：
10.1016/j.tecto.2016.02.039
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发表时间：
2016
期刊：
影响因子：
2.9
通讯作者：
Wigger
中科院分区：
文献类型：
--
作者：
Storch;Schmelzbach;Wigger
智利俯冲带弧和弧前的显著沟道平行断层系统可在南北方向上追踪数千公里。这些断裂系统可能横切俯冲大逆冲断层上方的整个地壳，并预计有一个密切的关系，俯冲地震周期的瞬态过程。为了对这些大规模断层带附近的结构目录和过程进行成像和表征，我们重新处理了ANCORP'96可控源地震数据集，以提供断层的深度图像，并将地表的地质信息与地下结构联系起来。这些断层系统周围观测到的震源位置与成像结果的相关性揭示了这些断层系统的地震活动的起源和性质。主动和被动地震数据一起产生的纵向山谷下在中地壳水平，这可以从俯冲板块界面的顶部观察到，这似乎是连接到在表面上已知的前心轴断层系统（PFS）的巨型逆冲断层的图片。这一结果支持了先前提出的构造模型，其中一个大规模的逆冲断层展布断层定义为地壳规模的断层弯曲褶皱的西高原。此外，我们清楚地成像两个分支的Uyuni-Kenayani故障（UKF）在0和20公里之间的深度范围。总之，这些断层的成像对于深刻理解俯冲带的构造评价和环境表征具有重要意义，本研究的结果为此提供了可靠的依据。
Prominent trench-parallel fault systems in the arc and fore-arc of the Chilean subduction zone can be traced for several thousand kilometers in north–south direction. These fault systems possibly crosscut the entire crust above the subduction megathrust and are expected to have a close relationship to transient processes of the subduction earthquake cycles. With the motivation to image and characterize the structural inventory and the processes that occur in the vicinity of these large-scale fault zones, we re-processed the ANCORP'96 controlled-source seismic data set to provide images of the faults at depth and to allow linking geological information at the surface to subsurface structures. The correlation of the imaging results with observed hypocenter locations around these fault systems reveals the origin and the nature of the seismicity bound to these fault systems. Active and passive seismic data together yield a picture of a megathrust splay fault beneath the Longitudinal Valley at mid-crustal level, which can be observed from the top of the subduction plate interface and which seems to be connected to the Precordilleran Fault System (PFS) known at the surface. This result supports a previously proposed tectonic model where a megathrust splay fault defines the Western Altiplano as a crustal-scale fault-bend-fold. Furthermore, we clearly imaged two branches of the Uyuni-Kenayani Fault (UKF) in a depth range between 0 and 20 km. In summary, imaging of these faults is important for a profound understanding of the tectonic evaluation and characterization of the subduction zone environment, for which the results of this study provide a reliable basis.
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DOI：
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发表时间：
2007
期刊：
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