Intra-arc strike-slip fault exposed at batholithic levels in the southern Sierra Nevada, California
Intra-arc strike-slip fault exposed at batholithic levels in the southern Sierra Nevada, California
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加利福尼亚州内华达山脉南部岩基层面暴露的弧内走滑断层
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
J. Saleeby
中科院分区：
文献类型：
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作者：
C. Busby;J. Saleeby
克恩峡谷断层是一条主要的北向断层，在加利福尼亚州内华达山脉南部绵延140公里。以往沿断裂北缘的地质填图和年代学研究表明，右旋偏移量发生在80 Ma之后至3.5 Ma之前，这种偏移量被解释为新生代盆山伸展的结果。我们对断层中央三分之一(克恩维尔-伊莎贝拉湖地区)的新结果表明，在内华达山脉最大的深成岩体侵位的同时，存在较早的右旋运动历史。较老的构造被称为原核峡谷断裂带。新生代断裂带是一条狭窄的脆性变形带，而白垩纪断裂带是一条宽阔的韧性变形带。参与韧性变形的深成岩和变质火山岩的锆石U-Pb年代学以及韧性变形后的岩体表明，原核峡谷断裂带在85 Ma时活动，最早可能在105 Ma开始活动。纵向走滑断层在现代岩浆弧中很常见，那里的会聚是倾斜的。原核峡谷断裂带可能是对Farallon板块俯冲过程中的适度北向分量的响应，也可能是对库拉板块的强烈北向分量的响应。
The Kern Canyon fault is a major north-trending fault that is continuous for a distance of 140 km in the southern Sierra Nevada, California. Previous geologic mapping and geochronological work along the northern third of the fault indicate that dextral offset occurred sometime after 80 Ma and before 3.5 Ma; this offset was interpreted to be the result of Cenozoic basin-and-range extension. Our new results from the central third of the fault (Kernville-Lake Isabella region) indicate an earlier right-lateral movement history, contemporaneous with emplacement of the largest plutons in the Sierra Nevada. The older structure is termed the proto-Kern Canyon fault zone. The Cenozoic fault trace is a narrow zone of brittle deformation, whereas the Cretaceous fault zone is a broad zone of ductile deformation. U-Pb zircon geochronology on plutonic and metavolcanic rocks involved in the ductile deformation, as well as a pluton that postdates ductile deformation, demonstrate that the proto-Kern Canyon fault zone was active at 85 Ma, and may have begun to move as early as 105 Ma. Longitudinal strike-slip faults are common in modern magmatic arcs where convergence is oblique. The proto-Kern Canyon fault zone may have originated in response to a moderate northward component in subduction of the Farallon plate or perhaps a strong northward component for the Kula plate.