Neotectonic Evolution of the Peripheral Zones of the Ordos Basin and Geodynamic Setting

based on satellite imagery interpretation, field structural measurements and morpho-tectonic analysis, this paper makes a brief synthesis on Cenozoic extensional history of the graben systems around the Ordos basin and delimits the lower bound of the initial age, 8~9 Ma, of Neotectonic era in the peripheral zones of Ordos. Neotectonic evolution has been divided into 3 stages with distinct morpho-tectonic features. An early stage during the Latest Miocene to Early Pliocene was characterized by development of the Red clay basin and by initiation of the Shanxi graben system. The peripheral zones of the Ordos was dominated by transtension. A middle stage during the Late Pliocene and middle Pleistocene experienced multi tectonic events that were characterized by episodic compressive deformation along the SW margin, continued subsidence of the graben system along NW and SE margins, uplift of the Ordos basin and development of erosional valley and river terraces along the Jin-Shan deep incised valley of the Yellow River. The most recent neotectonic stage since the middle to Late Pleistocene was dominated by deformation of transpression and transtension in the peripheral zones of Ordos, with intensification of differential vertical motion and river incision. Fault activities during the neotectonic era include different combination of normal, sinistral and dextral strike-slip and reverse faulting. The Ordos block itself rotates around vertical axis, which was accommodated by normal faulting and crustal extension along the graben system. The episodic evolution of neotectonics in the Ordos regions has been dynamically related to fast northward growth and episodic eastward extrusion of Tibetan Plateau during the Late Cenozoic time.