| 鄂尔多斯盆地侏罗纪西界分析 |
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| 引用本文： | 张珂,邹和平,刘忠厚,马占武.鄂尔多斯盆地侏罗纪西界分析[J].地质论评,2009,55(6). |
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| 作者姓名： | 张珂 邹和平 刘忠厚 马占武 |
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| 作者单位： | 1. 中山大学地球科学系,广州,510275
2. 核工业208大队,内蒙古包头,014010 |
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| 基金项目： | 中国核工业地质局鄂尔多斯盆地西部铀成矿规律研究项目(编号HDKY0506-1);;国家自然科学基金资助项目(编号40672124)的成果 |
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| 摘 要： | 鄂尔多斯盆地西界,特别是其早—中侏罗世盆地西界,由于不同期次、不同性质的构造相互叠加而模糊不清,究竟是在贺兰山以西还是现在银川盆地以东的问题,至今尚无共识,极大地影响着矿产资源的评价和找矿战略的部署。本文在前人工作的基础上,通过针对性的野外工作,分析和筛分了不同时期的古构造,探讨了晚侏罗世和早—中侏罗世盆地的西界。文章认为,鄂尔多斯盆地西部巨大的近南北向挤压构造形成于晚侏罗世,而东西向的挤压构造则出现于晚三叠世。两期方向截然不同的挤压构造相互叠加,构成了鄂尔多斯盆地西部复杂的叠加构造和不规则的盆地西界。晚期挤压构造较为清晰,表现为近南北向的逆冲推覆构造带和纵贯盆地南北的"古脊梁",使盆地西界退缩到桌子山东麓断裂、横山堡—磁窑堡断褶带以及马儿庄冲断裂和崆峒山断裂以东。早期挤压构造受后期构造的叠加改造,断断续续,时隐时现。近东西向挤压构造受古亚洲域的影响,是印支运动的产物,近南北向挤压构造转受滨太平洋域的作用,是燕山运动的表现。在古亚洲域向太平洋域转换过程中的早—中侏罗世,鄂尔多斯盆地西部出现了近东西向的拉张伸展,在盆地内部表现为近东西向隆起凹陷的古地形,使盆地西缘波状弯曲,而非平直,"银川古隆起"和"汝箕沟—鄂...
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| 关 键 词： | 鄂尔多斯盆地西界 侏罗纪 三叠纪 叠加构造 构造筛分 |
On the Jurassic West Boundary of the Ordos Basin |
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| ZHANG Ke,ZOU Heping,LIU Zhonghou,MA Zhanwu.On the Jurassic West Boundary of the Ordos Basin[J].Geological Review,2009,55(6). |
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| Authors: | ZHANG Ke ZOU Heping LIU Zhonghou MA Zhanwu |
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| Abstract: | Because different geological structures with different properties formed in different periods were superposed together, western boundary of the Ordos Basin, especially the one in the Early-Middle Jurassic, is obscure and not easy to be discerned. So far, there has been no consensus in academy whether it located on west of the Helan Mountain or on east of the Yinchuan Basin (a Cenozoic basin situated to east of the Helan Mountain), affecting mineral resource appraisal and exploration. Based on the former research and our work, different ancient structures formed in different periods in Mesozoic are analyzed and sieved, and then the Early-Middle Jurassic western boundary of the basin is recovered. Writers consider that the huge north-south compressive structure formed in the Late Jurassic while east-west compressive structure formed in the Late Triassic. These two structures were superposed together, resulting in multiple deformations, complex superimposed structures and the irregular west basin boundary. The structure later is much clearer, appearing as a north-south thrust zone and a north-south "the Ancient Land Rise" across the basin. Since formation of the north-south compressive structure, west boundary of the basin was retreated eastward to east of the Zhuozhi Mountain thrust, the Hengshanbao-Ciyaobao fault and fold zone, the Maerzhuang thrust fault as well as the Kongdong Mountain thrust fault. However, the early compressive structure is obscure, appearing discontinuously and indistinct because of superimposing and reforming by the later. The early east-west compressive structure formed in Indosinian movement under the ancient Asian tectonic domain, while the later north-south compressive structure formed in the Yanshanian movement under the Pacific tectonic domain. During the transitional period of the Early-Middle Jurassic from the Ancient Asian to Pacific tectonic domains, the west Ordos Basin had developed nearly east-west tensional structure, forming nearly east-west uplifts and depresses, resulting in irregular instead of linear west boundary at north-south trend. Under this situation, "the ancient Yinchuan uplifts" and "the large Ordos Basin" coexisted, not controversial. The west boundary in the Early-Middle Jurassic was probably located in the Alxa Massif. The Mesozoic structures above were reformed again in Cenozoic, making the former structures more complicated and even complete destroy. Paying attention to structural analysis and sieving would be very important in the discussion on the Mesozoic structures and ancient boundaries of the basin. |
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| Keywords: | west boundary of the Ordos Basin Triassic Jurassic superimposed structures structural sieving |
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