川西盆地早侏罗世沉积特征及原型盆地恢复

发布时间：2018-03-08 18:40

  本文选题：下侏罗统　切入点：川西盆地　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：川西盆地位于四川盆地西部,东以龙泉山断裂为界,西至龙门山构造带。中三叠世以前,川西盆地沉积了大规模的海相碳酸盐岩地层。晚三叠世进入陆相沉积环境,发育上三叠统-第四系巨厚沉积物。由于现今呈现出北东向龙门山逆冲推覆带、川西盆地、龙泉山前陆隆起相互平行的构造格局,故川西盆地被认为是晚三叠世以来龙门山构造带控制的前陆盆地。然而,龙门山中-南段显示灌县-安县断裂切割侏罗系,而且沉积物显示为砂泥岩相的远源性质,表明早侏罗世川西原型盆地西部边缘并非灌县-安县断层。因此,重建早侏罗世川西原型盆地对理解该时期盆-山关系有重要意义。本文利用中石化勘探开发井位资料,并与野外露头分析相结合,通过对川西盆地下侏罗统沉积相进行分析,识别出川西盆地从北到南,冲积扇-扇三角洲-滨浅湖-半深湖相沉积模式的变化,沉积相带呈近东西展布,龙门山仅在北段山前发育冲积扇沉积,南段滨浅湖-半深湖沉积表明龙门山南段与盆地边界并非现今位置。而整个早侏罗世盆地的沉降速率及早侏罗世晚期介壳滩相的大范围分布,表明早侏罗世盆地周缘造山带处于比较稳定的状态。沉积相带近东西的展布规律表明早侏罗世盆地主要受龙门山北段-米仓山控制,即秦岭南缘向西南扩展的逆冲构造控制。
[Abstract]:The western Sichuan basin is located in the west of Sichuan basin, bounded by Longquanshan fault in the east, and to the Longmenshan tectonic belt in the west. Before the middle Triassic, the western Sichuan basin deposited large-scale marine carbonate rocks, and the late Triassic entered the continental sedimentary environment. The very thick sediments of the Upper Triassic-Quaternary system are developed. Due to the present tectonic pattern of the NNE Longmenshan thrust nappe, the western Sichuan basin and the Longquanshan Foreland uplift are parallel to each other. Therefore, the western Sichuan basin is considered to be a Foreland basin controlled by the Longmenshan tectonic belt since the late Triassic. However, the mid-south section of Longmen Mountain shows the cut Jurassic of Guanxian-Anxian fault, and the sediment shows the distant nature of sand and mudstone facies. It shows that the western margin of the early Jurassic western Sichuan archetype basin is not Guanxian-Anxian fault. Therefore, it is important to reconstruct the early Jurassic west Sichuan archetype basin to understand the basin-mountain relationship in this period. In this paper, the exploration and development well location data of Sinopec are used. Combined with outcrop analysis in the field, the sedimentary facies of the Lower Jurassic in West Sichuan Basin are analyzed, and the sedimentary models of alluvial fan fan delta shoreside shallow lake and half deep lake are identified from north to south. The sedimentary facies belt is near east-west distribution, the Longmen Mountain only develops alluvial fan deposits in the northern part of the mountain front, The littoral and semi-deep lacustrine sediments in the southern part indicate that the boundary between the south part of Longmen Mountain and the basin is not present, while the subsidence rate of the whole early Jurassic basin is distributed in a wide range in the late Jurassic period. It indicates that the early Jurassic basin peripheral orogenic belt is in a relatively stable state, and the distribution of the sedimentary facies belt near the east and west shows that the early Jurassic basin is mainly controlled by the north segment of Longmen Mountain-Micang Mountain, that is, the thrusting structure extending southwestward from the southern margin of the Qinling Mountains.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P534.52
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本文编号：1585092