哈拉阿拉特山地区构造特征及成因机制模拟

Tectonic Characteristics and Genetic Simulation of Hala'alate Mountain Area

哈拉阿拉特山地区是准噶尔盆地西北缘山前冲断带的一部分,构造变形复杂。为研究哈山地区的构造变形过程及成因机制,在三维地震资料解释的基础上,根据构造变形样式的差异,划分为西、中、东三段。西段构造变形整体以推覆叠加为主,中段整体表现为冲断叠加的特征,东段主要表现为冲断褶皱的模式。构造变形过程主要经历了早二叠世伸展裂陷、中晚二叠世-三叠纪强烈逆冲推覆、侏罗纪-白垩纪弱挤压逆冲和新生代隆升兼走滑调整四个阶段。采用物理模拟手段对哈山地区不同区段典型剖面的构造变形过程进行了实验研究。结果表明,挤压速率和强度是决定哈山地区不同区段地层叠置程度的主要因素,塑性地层的分布控制了不同区段滑脱断层与冲断断层发育的先后顺序,而塑性地层的长度则决定了滑脱断层的规模。

The Hala＇alate mountain area is part of the mountain front thrust belt in the northwest margin of Junggar Basin, where the tectonic deformation is complicated. Based on interpretation of the three-dimensional seismic data, it can be divided into three segments. The structure of the Hala＇alate mountain area is characterized by nappe-superimposed deformation in the western part, trust-superimposed deformation in the middle part, and trust-fold deformation in the eastern part. Tectonic evolution consists of three stages： extension-rifted stage （P1）, strong thrust-nappe stage （P2-T）, weak compressional-thrust stage （J-K）, uplifting erosion and strike-slip adjustment stage （Cz）. To better understand the structural genetic mechanism, typical profiles of different segments in the study area were chosen to simulate the structural deformation processes. The experimental results show that the compress velocity and strength are the main controlling factors of strata and superposed extent. The location of ductile formations controlled the development sequence of the detachment fault and the thrust fault in different segments. The length of ductile formations controlled the scale of the detachment fault.