Three-dimensional mechanical modeling of the GPS velocity field around the northeastern Tibetan plateau and surrounding regions

• Published in: Tectonophysics 2013-01, Vol.584, p.257-266
• Main Authors: He, Jiankun, Lu, Shuangjiang, Wang, Weimin
• Format: Article
• Language: English
• Subjects: Active tectonics; Crusts; Faults; Friction; GPS; Mathematical models; Mechanical modeling; Northeastern Tibetan plateau; Rheology; Slip; Three dimensional models; Viscosity
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2012.03.025

The northeastern corner of the Tibetan plateau is a complex tectonic region with different fault mechanisms from left-lateral thrusting of the Qilian Shan, left-lateral strike slipping of the Haiyuan fault along the plateau edge, and right-lateral extension across the Alashan and the Ordos out of the northeastern Tibetan plateau. Here, we use 3D finite element models incorporating fault as Coulomb-type friction zone to investigate mechanical relation between crustal rheology and long-term deformation of the main active fault systems. Models are constrained with GPS velocity field and available geological slip rates. Crustal rheology is simplified as an elastobrittle upper part, underlying with viscoelastic crust. We test models with fault frictions (μ) from 0.4 to 0.02 on different fault systems, and mean viscosities (η) of the lower crust from 1019Pa.s to 1021Pa.s in the Tibetan plateau and 1021Pa.s to 1023Pa.s out of the Tibetan plateau. A common feature from the numerical experiments is that the Haiyuan fault reflects a low fault friction (μ