科研之友
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摘要
The ca. 700-km long Yalu River Fault Zone (YRFZ) is a major component of the NE striking strike-slip fault system of the East Asia continental margin, which was active during the late Mesozoic. Despite its importance, the origin and timing of activity along the fault zone remain unclear. We present structural data that indicate that the NE striking YRFZ was initiated as a sinistral strike-slip fault zone. Ductile, brittle-ductile, and brittle structures are exposed along its length, with more ductile structures in the southwest. The shear belts and faults predominantly dip steeply to the southeast and have a minor reverse component of motion. Microstructures indicate deformation temperatures of similar to 300 degrees C-500 degrees C for the ductile region and similar to 200 degrees C-300 degrees C for the brittle-ductile region. Inversion of fault slip data measured from brittle faults indicates that the sinistral motion was a result of N-S compression. We present in situ zircon U-Pb dating results for deformed and undeformed igneous rocks sampled from the ductile shear belts, indicating that sinistral faulting occurred between 146 and 131Ma. This result correlates with the timing of a regional N-S shortening event during the earliest Early Cretaceous. Our data, together with other published studies of this strike-slip fault system, suggest that the East Asia shear margin was initiated at the beginning of the Early Cretaceous with the synchronous formation of a series of NE to NNE striking sinistral faults. This brief transpressive event along the shear margin was a result of the rapid, oblique subduction of the Izanagi Plate along a NNE trending trench.
- 出版日期2018-6
- 单位合肥工业大学
