鄂尔多斯盆地周边地带新构造演化及其区域动力学背景

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

基于卫星遥感影像解释、野外构造测量和构造-地貌分析，综述了鄂尔多斯盆地周边地带新牛代伸展断陷历史，初步论证了盆地周边地区新构造时期的下限为8～9Ma，并将新构造时期划分为3个构造-地貌演化阶段：（1）新构造前奏阶段（中新世晚期至上新世早期），以鄂尔多斯红粘土盆地的发育和山西地堑系的形成为标志，整个地区处于走滑伸展心力环境；（2）新构造主变动阶段（上新世晚期至中更新世），经历了多幕次构造变动事件，主要表现为沿西南缘弧形构造带的幕式挤压、周缘地堑盆地的持续伸展、鄂尔多斯盆地整体抬升、晋陕黄河峡谷段侵蚀盆地的形成和河流高阶地发育；（3）最新构造变动阶段（中晚更新世以来），以周缘地带的走滑挤压和走滑伸展变形为主要特征，盆地内部差异性隆升和河流下切侵蚀作用加强。新构造时期断裂运动方式主要有伸展、走滑和挤压逆冲活动，鄂尔多斯地块本身发生绕直立轴旋转，并为周缘地带地壳伸展变形所调节。鄂尔多斯地区新构造阶段性演化与青藏高原晚新生代快速向北扩展和高原物质向东构造挤出作用存在密切的动力学联系。

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.