关键词: 北天山山前, 逆冲推覆, 断层相关褶皱, 正演平衡地质剖面, 托斯台背斜

Abstract:

The Tuositai Anticline, which locates in the western section of the southern Junggar Basin foreland, has been strongly deformed. It is a complex superimposed fault-related fold in the piedmont of the northern Tianshan Mountains with rich fault-related folding marks exposed on the surface.Basing on geometric analyzing of a 2-D seismic line through the Tuositai Anticline constrained by the surface data and the well information, the present paper established the reasonable structural geometric model of the Tuositai Anticline.And then, a geometric numeral simulation cooperated with the geometry of the fault-related folding was developed, and its kinematics are also reconstructed by constructing a series of forward balanced geological cross-sections. The study results indicates that the Tuositai Anticline is a superimposed fold, and its thrusting and corresponding structural overlapping has been experienced several times. During the Jurassic to the Cretaceous, two southern dipping thrust faults had developed at the southern limb of the Tuositai Anticline,which forming a duplex structure, with the Jurassic and the Pre-Jurassic formations were thrust from south to the surface. After that, during the late Himalayan orogeny, another south dipping blind thrust have developed under the pre-existing duplex Tuositai Anticline, thus forming the present Tuosital Anticline with a total 12 km displacements.

Key words: piedmont of the northern Tianshan Mountains, overthrust folding, fault-related fold, forward-balanced geological cross-section, Tuositai Anticline