Kinematics of the active West Andean fold‐and‐thrust belt (central Chile): Structure and long‐term shortening rate
Kinematics of the active West Andean fold‐and‐thrust belt (central Chile): Structure and long‐term shortening rate
复制标题
活跃的西安第斯褶皱逆冲带（智利中部）的运动学：结构和长期缩短率
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
G. Vargas
中科院分区：
文献类型：
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作者：
M. Riesner;R. Lacassin;M. Simoes;R. Armijo;R. Rauld;G. Vargas
最近在安第斯山脉的西部前缘发现了与纳斯卡-南美洲俯冲界面合成的西向逆冲断层。在33°30′S附近，活动的San Ramón断层是这些西缘构造的最前沿，对智利首都圣地亚哥构成了重大地震威胁。在这里，我们根据野外观测、卫星图像和以前的构造数据以及数字地形，详细绘制了西安第斯褶皱冲断带的详细三维构造图和精确剖面图。然后，我们重建的演变，这锋面带使用三剪运动学的方法。我们的重建意味着向西传播的变形与9-15公里的总缩短累积在过去的2500万年。推断出总体长期缩短率为0.1-0.5 mm/年。该缩短率的最大值与从最近横跨圣拉蒙断层的海沟数据和与过去两次Mw > 7地震相关的滑动推断的缩短率相比很好。这表明，圣拉蒙断层很可能是西安第斯褶皱冲断带目前唯一的活动断层，并且大部分（如果不是全部）变形将通过地震释放。
West verging thrusts, synthetic with the Nazca‐South America subduction interface, have been recently discovered at the western front of the Andes. At ~33°30′S, the active San Ramón fault stands as the most frontal of these west verging structures and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a detailed 3‐D structural map and a precise cross section of the West Andean fold‐and‐thrust belt based on field observations, satellite imagery, and previous structural data, together with digital topography. We then reconstruct the evolution of this frontal belt using a trishear kinematic approach. Our reconstruction implies westward propagation of deformation with a total shortening of 9–15 km accumulated over the last 25 Myr. An overall long‐term shortening rate of 0.1–0.5 mm/yr is deduced. The maximum value of this shortening rate compares well with the rate that may be inferred from recent trench data across the San Ramón fault and the slip associated with the past two Mw > 7 earthquakes. This suggests that the San Ramón fault is most probably the only presently active fault of the West Andean fold‐and‐thrust‐belt and that most—if not all—the deformation is to be released seismically.
影响因子：
5.3
作者：
Fosdick, Julie C.;Carrapa, Barbara;Ortiz, Gustavo
通讯作者：
Ortiz, Gustavo