Abstract

ZHANG, Xiaoning  and  DONG, Yunpeng. The geological and geodynamic condition on the formation of the Dabashan thrust nappe structure: Based on FLAC numerical modelling. Earth Sci. Res. J. [online]. 2016, vol.20, n.4, pp.B1-B10. ISSN 1794-6190.  https://doi.org/10.15446/esrj.v20n4.38666.

The Dabashan thrust nappe structure at the southern margin of the Qinling orogenic belt suffered at least two stages of evolution which are Late Triassic plate subduction collisional orogeny between North China block, Qinling micro-plate and Yangtze block followed by intracontinental orogeny since the Meso-Cenozoic. A prominent topography characteristic within the Dabashan area is a southwestward extrusive arc (Bashan Arc fault) that is one of key factors to understand the geodynamic condition of the Dabashan thrust nappe structure.

In this work, two-dimensional plan-view models are constructed to simulate the collisional and intracontinental orogenic movements, and the factors that may control the formation of the Bashan Arc fault are analysed. The modelling results show that the compressive stress produced by the plates collision along both north and south boundaries is the main driving force. The dextral shearing derived from the inconsistent shape on the block margins is the main controller. Rigid tectonic units such as Bikou and Hanan-Micangshan terranes, Foping and Wudang domes, as well as Shennongjia-Huangling anticline also contribute as "anchor" effects. Additionally, the rheology properties of rock material in the Dabashan area affect the shape of the arc.

Keywords : Numerical modelling; South Qinling; Bashan Arc; Dabashan; Thrust nappe structure.

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