ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    准噶尔盆地南缘中段山前复杂构造变形特征及形成演化

    Complex Tectonic Deformation Characteristics, Formation and Evolution of the Mountain Front in the Middle Part of the Southern Margin of Junggar Basin

    • 摘要: 准噶尔盆地南缘中段紧邻北天山山前,构造变形错综复杂。山前发育的三排构造的形成时间存在许多认识上的分歧,对演化过程中褶皱和断裂的变形叠加特征缺少系统的对比分析。笔者在前人研究的基础上,利用地震资料解释、平衡剖面恢复、构造物理模拟等研究手段,结合断层滑移距、伸展压缩速率定量分析方法,对研究区的构造变形特征和叠加演化过程进行了系统的分析。研究认为:①南缘中段三排构造自南向北,变形强度由强变弱;第一排背斜受控于基底卷入型断裂体系,第二、三排背斜受控于顺层滑脱型断裂体系,构造之间具有形成递进的演化关系,叠加形成多种复合构造样式。②断层滑移距总体“由深至浅”逐渐变小,具有继承性发育的特点;主干断裂滑移距存在明显的拐点,是多期次活动的有力证据。③基底大型逆冲断裂是先存断裂,后期继承性发育;基底卷入型褶皱–冲断带是褶皱作用发生在逆冲断裂之前,后期表现出边断边褶特征;滑脱型褶皱–冲断带是冲断和褶皱同时或冲断先于褶皱形成。④第一排背斜形成于侏罗纪末期,第二排背斜在此时期形成微弱雏形,并在古近纪末期形成明显轮廓;第三排背斜形成于新近纪末期;第四纪至今的强大挤压作用使3排背斜被断裂强烈改造。

       

      Abstract: The middle part of the southern margin of the Junggar Basin is adjacent to the North Tianshan Mountain Front, and the tectonic deformation is intricate and complex. There are many differences in the understanding of the formation time of the three rows of structures developed in the mountain front, and there is a lack of systematic comparative analysis of the deformation superposition characteristics of folds and fractures during the evolution. In this paper, on the basis of previous studies, the research tools such as seismic data interpretation and equilibrium profile recovery are used, combined with the quantitative analysis methods of fault slip distance and extensional compressional rate, to make a systematic analysis of the tectonic deformation characteristics and superposition evolution process in the study area. The study concludes that: ① The three rows of structures in the middle section of the southern margin from south to north, the deformation intensity from strong to weak; the first−row anticlines are controlled by the basement−involved fault system, and the second−row and third−row anticlines are controlled by the bedding−decollement fault system. There is a progressive evolution relationship between the structures, and a variety of composite structural styles are superimposed. ② The fault slip distance gradually decreases from deep to shallow, with the characteristics of inheritance development; there is an obvious inflection point in the slip distance of the main fracture, which is a strong evidence of multi−stage activity. ③ The basement large−scale thrust fault is a pre−existing fault, and later inherited development; the basement−involved fold−thrust belt is characterized by fold while fault in the later period when fold occurs before thrust fault; the detachment foldthrust belt is formed by thrust and fold at the same time or thrust before fold.④ The first row of anticlines formed in the late Jurassic, and the second row of anticlines formed a weak prototype in this period, and formed a clear outline in the late Paleogene; the third row of anticlines formed in the late Neogene; the strong extrusion effect since the Quaternary period has made the three−row anticline strongly modified by fracture.

       

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