| 川东褶皱带构造发育深度层次与变形样式 |
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| 引用本文： | 徐汀滢,季建清,涂继耀,刘志成.川东褶皱带构造发育深度层次与变形样式[J].地质科学,2012,0(3):788-807. |
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| 作者姓名： | 徐汀滢 季建清 涂继耀 刘志成 |
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| 作者单位： | 北京大学地球与空间科学学院,造山带与地壳演化教育部重点实验室北京 100871 |
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| 摘 要： | 地壳上层的结构特征和变形样式在垂直方向上的变化远远大于其在水平维度上的分异。川东褶皱带自晚古生代以来地史演化统一、地层展布稳定,之后新生代盆、山演化分异幅度较大,使得不同深度的地层和基底得以出露,不同地壳深度层次的构造样式得以展示,这为研究应力的垂向分异,提供了很好的条件。本文基于地壳垂直方向上变形几何的不守恒、构造脱耦以及构造层次的概念,通过野外构造现象的详细解析、野外脆性破裂产状统计、断裂之间交切关系以及活动性质观察等综合分析,结合遥感图像研究,对川东褶皱区隔挡式褶皱和隔槽式褶皱形成提出了新的解释模型。以华蓥山与齐岳山为界,川东褶皱带被分为3个呈叠置关系的区域。研究表明华蓥山以西(Ⅰ区)没有发生强烈的构造变形,变形深度最小(<2 km); 华蓥山与齐岳山之间(Ⅱ区)构造样式为在北北东向剪切作用下形成的陡立构造面理,变形深度为2～5 km; 而齐岳山以东(Ⅲ区)的构造样式是发育轴向北东的宽缓褶曲,变形深度为4～6.6 km。研究分析后得出,川东褶皱带在晚古生代以来,没有经历过大幅度的地壳垂向运动和明显的旋转运动,而白垩纪以后,发育了早期北北东向和晚期北东向的两期构造变形。Ⅱ、Ⅲ两区的构造样式发育于同一应力场(北西-南东主应力场),而晚期北东向断裂活动是形成上述3个区域呈现出断块并置的原因。另外,由于后期不同断块抬升和剥露的差异,使3个区域迥异的构造样式呈现在地表。这一认识对研究油气相关的构造圈闭、固体多金属矿产相关的矿床深度问题以及大地构造学等问题都有创新意义。
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| 关 键 词： | 川东褶皱带 变形样式 深度层次 构造脱耦 |
| 收稿时间： | 2012-02-20 |
| 修稿时间： | 2012-02-20; |
Tectonic levels and deformation patterns of the eastern Sichuan fold belt |
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| Xu Tingying,Ji Jianqing,Tu Jiyao,Liu Zhicheng.Tectonic levels and deformation patterns of the eastern Sichuan fold belt[J].Chinese Journal of Geology,2012,0(3):788-807. |
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| Authors: | Xu Tingying Ji Jianqing Tu Jiyao Liu Zhicheng |
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| Institution: | Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Science,Peking University,Beijing 100871 |
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| Abstract: | Variation of structure and deformation patterns is much greater in the vertical dimension than it is in the horizontal dimension in the upper crust.eastern Sichuan fold belt features a stable geological evolution and strata occurrence since Late Paleozoic.However,the crust uplift since Later Cenozoic makes the strata and the basement with various depth exposed and distinct structural styles in different depth of the crust were displayed,providing ideal exposures for the study of tectonic levels.This paper proposes a new model to explain the formation of comb-like and trough-like folds in the eastern Sichuan fold belt through detailed structure analysis,combined with remote sensing images.Take Huaying Mountain and Qiyue Mountain as boundaries,the eastern Sichuan fold belt is divided into three superposed blocks.Block-Ⅰis to the west of Huaying Mountain with the smallest(<2 km)deformation depth and no obvious deformation was seen.Block-Ⅱ lies between the Huaying Mountain and the Qiyue Mountain.The deformation style is steep structural foliations formed by NNE-trending shearing and the depth of deformation is 2～5 km.Block-Ⅲ is to the east of Qiyue Mountain.The deformation style is characterized by broad and gently-dipping folds with axis trending NE and the deformation depth is 4～6.6 km.Different from the calm period from Paleozoic to Mesozoic,two stages of deformation-the early NNE-trending faults and the later NE-trending faults-were developed in the eastern Sichuan fold belt since late Cretaceous.The broad and gentle folds in Block-Ⅲ and the NNE-trending steep cleavages in Block-Ⅱ were developed under the same NW-SE compressive stress field.The later NE-trending faults caused the above three regions to be superposed as fault blocks.Due to the different uplift and exhumation rates of the blocks,the structural styles in different depth and deformation patterns in the three regions formed in the early deformation stage were displayed to the surface.This research bears significance for the innovation and studies of oil and gas traps,mineral deposit as well as other tectonics subjects. |
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| Keywords: | Eastern Sichuan fold belt Deformation patterns Tectonic levels Structural decoupling |
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