COLLABORATIVE RESEARCH: Studies of Large-Magnitude Intra- continental Extensional Strain, Death Valley Region, California

利用前第三纪逆冲断层和古生代地层走向等前伸展标志，模拟了加州死亡谷地区的大规模陆内伸展。该模型表明，整个地区的伸展是由大陆地壳上部15公里沿一个宽度小于10公里的离散的、向西倾斜的正断层带的大规模分离所容纳的。在随后150公里的分离过程中，深层地壳以均衡的方式上升，填满了分离板块之间留下的空隙。体积上较小的断层条体依次从上盘块体转移到分离的断层条体，明显停止了主要的伸展，并随上盘向西迁移。本项目将利用构造制图、古地磁和热年代学对该模型进行严格检验。研究结果对美国西南部构造和大规模大陆伸展的一般过程具有重要意义。

Large-magnitude intracontinental extension in the Death Valley region of California has been modeled by using pre-extensional markers such as pre-Tertiary thrust faults and Paleozoic strati- graphic trends. The model indicates that extension across the region was accommodated by wholesale separation of the upper 15 km of the continental crust along a discrete, west-dipping zone of normal faults less than 10 km in width. During the ensuing 150km of pull apart, deep crust rose isostatically and filled the void left between the separating blocks. Volumetrically minor fault slivers were sequentially transferred from the hanging wall block to the detached slivers and apparent cessation of major extension migrated westward with the hanging wall. This project will use structural mapping, paleomagnetism and thermochronology of the slivers to rigorously test this model. Results are of importance to south-western U.S. tectonics and to the general process of large-scale continental extension.