Fault Slip and GPS Velocities Across the Shan Plateau Define a Curved Southwestward Crustal Motion Around the Eastern Himalayan Syntaxis

作者：Shi, Xuhua^*; Wang, Yu; Sieh, Kerry; Weldon, Ray; Feng, Lujia; Chan, Chung-Han; Jing Liu-Zeng

来源：JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2018, 123(3): 2502-2518.

DOI：10.1002/2017JB015206

• SICHUAN-YUNNAN REGION
• RED-RIVER FAULT
• BIEN-PHU FAULT
• TIBETAN PLATEAU
• SHEAR ZONE
• SURFACE DEFORMATION
• SOUTHEASTERN MARGIN
• ACTIVE TECTONICS
• COLLISION ZONE
• DIANCANG SHAN

Characterizing the 700 km wide system of active faults on the Shan Plateau, southeast of the eastern Himalayan syntaxis, is critical to understanding the geodynamics and seismic hazard of the large region that straddles neighboring China, Myanmar, Thailand, Laos, and Vietnam. Here we evaluate the fault styles and slip rates over multi-timescales, reanalyze previously published short-term Global Positioning System (GPS) velocities, and evaluate slip-rate gradients to interpret the regional kinematics and geodynamics that drive the crustal motion. Relative to the Sunda plate, GPS velocities across the Shan Plateau define a broad arcuate tongue-like crustal motion with a progressively northwestward increase in sinistral shear over a distance of similar to 700 km followed by a decrease over the final similar to 100 km to the syntaxis. The cumulative GPS slip rate across the entire sinistral-slip fault system on the Shan Plateau is similar to 12 mm/year. Our observations of the fault geometry, slip rates, and arcuate southwesterly directed tongue-like patterns of GPS velocities across the region suggest that the fault kinematics is characterized by a regional southwestward distributed shear across the Shan Plateau, compared to more block-like rotation and indentation north of the Red River fault. The fault geometry, kinematics, and regional GPS velocities are difficult to reconcile with regional bookshelf faulting between the Red River and Sagaing faults or localized lower crustal channel flows beneath this region. The crustal motion and fault kinematics can be driven by a combination of basal traction of a clockwise, southwestward asthenospheric flow around the eastern Himalayan syntaxis and gravitation or shear-driven indentation from north of the Shan Plateau.

• 出版日期2018-3
• 单位南阳理工学院; 中国地震局