Pulsed deformation and variable slip rates within the central Himalayan thrust belt
Pulsed deformation and variable slip rates within the central Himalayan thrust belt
复制标题
喜马拉雅冲断带中部的脉冲变形和可变滑移率
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
N. McQuarrie
中科院分区：
文献类型：
--
作者：
D. Robinson;N. McQuarrie
来自喜马拉雅冲断带和尼泊尔西部远的前陆盆地的正演模拟重建和数据将侵蚀去顶和相关沉积与断层运动的运动学和年龄联系起来。我们通过一个向前传播的、相互连接的褶皱-冲断带-前陆盆地系统再现了在地表识别的变形艾德。这种方法允许在每个时间步长的侵蚀程度和相关的前陆盆地的范围，深度和年龄的估计。模型重建显示，为前陆盆地提供沉积物的单元随着时间的推移而变化：25 - 13 Ma，特提斯喜马拉雅的侵蚀;约25 - 13 Ma，特提斯喜马拉雅的侵蚀。12 Ma，大喜马拉雅第一次暴露;约。11 Ma，小喜马拉雅首次出露。在我们的模型中，大喜马拉雅山和小喜马拉雅山岩石的暴露与逆冲斜坡的形成有关，逆冲斜坡穿过7 km的下盘小喜马拉雅山地层，并将>7 km的小喜马拉雅山岩石平移到斜坡上，形成小喜马拉雅山复式。构造起伏的增加集中了斜坡区域的侵蚀，并促进了大喜马拉雅和元古代小喜马拉雅岩石的暴露。随着小喜马拉雅斜坡向南传播，更多的小喜马拉雅逆冲岩席被纳入小喜马拉雅复式。虽然确定逆冲事件的唯一年代具有挑战性，但这些模型重建使我们能够将时间步长与沉积或折返的年龄联系起来。出现的是随时间变化的变形克里思，其特征是在主中央冲断层、Ramgarh冲断层的传播过程中以及小喜马拉雅复式构造发展的中期阶段（~25 - 30 mm/年）迅速缩短。在Ramgarh逆冲断层就位后，小喜马拉雅复式构造的早期和晚期以缓慢缩短（~13 - 14 mm/年）为标志。虽然长期和现代（大地测量）的变形速率约为20毫米/年，但随着时间的推移，缩短速率从4毫米/年到33毫米/年不等。
Forward modeling reconstructions and data derived from the Himalayan thrust belt and the foreland basin of far western Nepal tie the erosional unroofi ng and associated deposition to the kinematics and age of fault motion. We reproduce the deformation identifi ed at the surface through a forward-propagating, linked fold-and-thrust belt‐foreland basin system. This approach permits estimates of the magnitude of erosion at each time step and the extent, depth, and age of the associated foreland basin. The model reconstructions reveal that the units that supplied the sediment to the foreland basin changed through time: 25‐13 Ma, erosion of the Tethyan Himalaya; ca. 12 Ma, fi rst exposure of the Greater Himalaya; ca. 11 Ma, fi rst exposure of the Lesser Himalaya. In our model, exposure of Greater Himalaya and Lesser Himalaya rock is associated with the formation of a thrust ramp that cuts through 7 km of footwall Lesser Himalaya stratigraphy and translates >7 km of Lesser Himalaya rock over the ramp, forming a Lesser Himalaya duplex. An increase in structural relief focuses erosion over the region of the ramp and facilitates exposure of Greater Himalaya and Proterozoic Lesser Himalaya rocks. As the Lesser Himalaya ramp propagates southward, more Lesser Himalaya thrust sheets are incorporated into the Lesser Himalaya duplex. Although uniquely dating thrust events is challenging, these model reconstructions allow us to associate time steps with an age of deposition or exhumation. What emerges is a tempo of deformation that varies with time, marked by periods of rapid shortening during propagation of the Main Central thrust, Ramgarh thrust, and middle stages of the development of the Lesser Himalaya duplex (~25‐30 mm/yr). After emplacement of the Ramgarh thrust, early and late stages of Lesser Himalaya duplex development are marked by periods of slow shortening (~13‐14 mm/yr). Although longterm and modern (geodetic) rates of deformation agree at ~20 mm/yr, rates of shortening through time have varied from 4 to 33 mm/yr.
影响因子：
5.8
作者：
Hetzel, Ralf;Dunkl, Istvan;Frei, Dirk
通讯作者：
Frei, Dirk