Slip partitioning along a continuously curved fault: Quaternary geologic controls on Denali fault system slip partitioning, growth of the Alaska Range, and the tectonics of south-central Alaska
Slip partitioning along a continuously curved fault: Quaternary geologic controls on Denali fault system slip partitioning, growth of the Alaska Range, and the tectonics of south-central Alaska
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沿连续弯曲断层的滑移划分：第四纪地质对德纳利断层系滑移划分、阿拉斯加山脉的生长以及阿拉斯加中南部的构造的控制
作者：
Sean P. Bemis;R. Weldon;G. Carver
活动的逆挤压断裂系统通常与广泛变形带的发育和地形发育有关；然而，复杂的几何形状通常与这些系统相关联，往往使其难以分离出控制逆转造山生长的重要边界条件。由于德纳里断裂的存在，人们普遍认为德纳里断裂系统是逆挤压的，德纳里断裂是一个主要的、活跃的、右侧的断裂，以及沿阿拉斯加山脉南北两侧的逆冲断层和与断层相关的褶皱的亚平行带。迪纳里断裂系统及其邻近的部分逆冲系统存在第四纪和全新世的滑动速率测量，但该逆冲系统的收缩和平移分量之间的断层滑动划分尚未得到详细研究。利用迪纳利断层相对简单的几何形状，我们分析了阿拉斯加山脉内活动断层的样式和分布，以确定应变调节模式，并确定收缩和平移应变如何在迪纳利断层系统中划分。由于德纳里断裂的轨迹在阿拉斯加中部弯曲了约70°，冲断系统的平均走向向北保持与德纳里断裂近平行，而在南部，少数已知或怀疑第四纪偏移的断裂向德纳里断裂倾斜。这一关系表明，由于地纳里断裂系统容纳了局部断层平行走滑，它将区域北西向板块运动的残余部分划分为地纳里断裂以南的北西-东南缩短和垂直于地纳里断裂以北的缩短。对Denali断裂系统产生位移的两条主要断裂（东Denali断裂和Totschunda断裂）的滑动分配程度与平衡的滑动预算相一致。现今迪纳里断裂以南的位移倾角是晚新生代toschunda断裂发育的结果，这为费尔韦瑟变换断裂向迪纳里断裂系统的应变传递提供了更直接的联系。传播应变分为迪纳利断层上的右侧滑动和阿拉斯加山脉逆冲断层的迪纳利断层正缩短，以及阿拉斯加内陆北部分布的左侧滑动断层。
Active transpressional fault systems are typically associated with the development of broad zones of deformation and topographic development; however, the complex geometries typically associated with these systems often make it difficult to isolate the important boundary conditions that control transpressional orogenic growth. The Denali fault system is widely recognized as transpressional due to the presence of the Denali fault, a major, active, right-lateral fault, and subparallel zones of thrust faults and fault-related folding along both the north and south flanks of the Alaska Range. Measured Quaternary and Holocene slip rates exist for the Denali fault system and portions of the adjacent thrust system, but the partitioning of fault slip between contractional and translational components of this transpressional system has not been previously studied in detail. Exploiting the relatively simple geometry of the Denali fault, we analyze the style and distribution of active faulting within the Alaska Range to define patterns of strain accommodation and determine how contractional and translational strain is partitioned across the Denali fault system. As the trace of the Denali fault curves by ∼70° across central Alaska, the mean strike of the thrust system to the north remains subparallel to the Denali fault, while to the south, the few faults with known or suspected Quaternary offset are oblique to the Denali fault. This relationship suggests that as the Denali fault system accommodates local fault-parallel strike slip, it partitions the residual part of the regional NW-directed plate motion into NW-SE shortening south of the Denali fault and shortening perpendicular to the Denali fault to the north. The degree of slip partitioning is consistent with a balanced slip budget for the two primary faults that contribute displacement to the Denali fault system (the eastern Denali fault and Totschunda fault). The current obliquity of displacement south of the Denali fault is the result of the late Cenozoic development of the Totschunda fault, which provides a more direct connection for the transfer of strain from the Fairweather transform fault to the Denali fault system. The transmitted strain is partitioned into right-lateral slip on the Denali fault and into Denali fault-normal shortening that is accommodated by thrust faulting in the Alaska Range and distributed left-lateral slip faulting within interior Alaska to the north.