Lithospheric-scale fault systems control the large-scale permeability in the Earth's crust and lithospheric mantle, and its proper recognition is fundamental to understand the geometry and distribution of mineral deposits, volcanic and plutonic complexes and geothermal systems. However, their manifestations at the current surface can be very subtle, as in many cases they are oriented oblique to the current continental margin and to the axis of the magmatic arc; be partially obliterated by younger, arc-parallel faults; and also be covered by volcanic and sedimentary deposits, through which the fault might propagate vertically.The Piuquencillo fault system (PFS) is a proposed lithospheric-scale fault system, located in the Main Cordillera of central Chile. Here, we present the results of the first detailed field study of the PFS, based on structural data collected at 82 structural stations distributed across all the western Main Cordillera. The first published U–Pb zircon ages for the La Obra batholith, which is bounded to the south by the PFS but also affected by younger reactivations of it, were obtained. They yielded 20.79 ± 0.13 Ma (granodiorite) and 20.69 ± 0.07 Ma (monzogranite). Statistical analysis of fault-plane data shows that the presence of the PFS is reflected on a strong preferred NW to WNW strike, with variable dip directions, evident from the analysis of the total fault-plane population and also from individual segments of the PFS. In some segments, the presence of major NE- to ENE-striking faults which intersect the PFS is also reflected in the preferred orientation of fault planes. Preferred orientations of hydrothermal veins, breccias and dikes show that both the PFS and some ENE-striking faults were capable of channelling hydrothermal fluids and magma. Kinematic and dynamic analysis of fault-plane data reveals that most of the PFS was reactivated with sinistral ± reverse kinematics during the Neogene, under a strike-slip to transpressive regime with E- to ENE-trending shortening direction (σ₁). Detailed kinematic and dynamic analyses were completed for various segments of the PFS and also for the different rock units affected by it.This study supports the concept that the PFS is a lithospheric-scale fault system, which strongly controlled deformation and the flow of magmas and hydrothermal fluids during the Neogene. The PFS forms part of a larger, margin-transverse structure, the Maipo deformation zone, a continental-scale discontinuity which cut across the entire Chilean continental margin and has been active at least since the Jurassic.

中文翻译：

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Piuquencillo断层系统：一个长寿的安第斯横向断层系统及其与岩浆和热液活动的关系

岩石圈规模的断层系统控制着地壳和岩石圈地幔的大规模渗透性，对它的正确认识是理解矿床，火山和古生复合体以及地热系统的几何结构和分布的基础。但是，它们在当前地表的表现可能非常微妙，因为在许多情况下，它们的方向与当前大陆边缘和岩浆弧的轴线倾斜；被年轻的弧形平行断层部分遮盖；Piuquencillo断层系统（PFS）是一个拟建的岩石圈规模的断层系统，位于智利中部的主要山脉，并可能被火山和沉积物所覆盖。在这里，我们介绍了PFS的首次详细实地研究的结果，基于分布在整个西部Main Cordillera的82个结构站的结构数据。获得了La Obra岩床的最早公布的U–Pb锆石年龄，该岩床由PFS限制在南部，但也受到较年轻的活化作用的影响。他们产生了20.79 ±  0.13 Ma（角铁闪长岩）和20.69  ±  0.07 Ma（单晶花岗岩）。对断层平面数据的统计分析表明，PFS的存在反映在西北偏西偏西偏西走向强烈偏爱的走向上，具有不同的倾角，这从对总断层面总体的分析以及从PFS的各个部分中可以明显看出。在某些部分中，与PFS相交的主要NE向ENE碰撞断层的存在也反映在断层平面的首选方向上。热液脉，角砾岩和堤防的优选方向表明，PFS和一些ENE冲动断层都能够引导热液和岩浆。对断层平面数据的运动学和动态分析表明，大多数PFS都通过正弦±来重新激活。  新近纪期间反向运动学，走滑到transpressive制度与E-到ENE向的缩短方向下（σ ₁）。对PFS的各个部分以及受其影响的不同岩石单元进行了详细的运动学和动力学分析。本研究支持PFS是岩石圈规模断层系统的概念，该系统强烈控制了岩浆和岩浆的变形和流动。新近纪时期的热液。PFS是较大的边缘横向结构迈坡变形带的一部分，该带是大陆规模的不连续面，横跨智利的整个大陆边缘，至少从侏罗纪开始就活跃了。