论文部分内容阅读
本文通过对安徽桐城挂车河、宿松河塌下-中侏罗统剖面岩石特征、沉积构造、粒度和碎屑组分的分析,揭示了燕山早期大别山隆升和侵蚀的演化历史;并结合构造变形分析,探讨了研究区区域动力学背景。结果显示,两地在早-中侏罗世时期分别为扇三角洲—半深湖和河道一河泛平原沉积,物源都来自北部的大别山。又因为挂车河剖面富含大别山变质碎屑颗粒,而河塌剖面相对缺少,由此提出大别山带南部在早.中侏罗世时期,东南部比西南部隆升较高;而相比大别山北麓的砾石和碎屑组成,则认为大别山北部隆升剥蚀更快,且剧烈。两剖面碰撞造山—火山岛弧和再旋回造山带大洋物质的物源,指示由北向南海沟—岛弧和盆地的构造格局。依据两地断层面和擦痕产状进行古应力分析,显示研究区晚侏罗世受到了燕山主幕近南北向的挤压应力。桐城挂车河的另一近东西向挤压应力可能表明该时期大别山东南部地区已受古太平洋构造的改造。
Based on the analysis of rock characteristics, sedimentary structure, grain size and detrital components of the Trachment-Susong-Middle Jurassic section of Tongcheng, Tongcheng River, Anhui Province, this paper reveals the evolution history of the uplift and erosion of Dabieshan in the early Yanshan Mountain. Deformation analysis, the study area of regional dynamics background. The results show that the two places were mainly fan delta - semi-deep lake and river-river pan-plains in the early-middle Jurassic period, respectively, with the provenance from the Dabie Mountains in the north. Because the trailer river profile is rich in Dachan metamorphic detrital particles, and the river lacustrine profile is relatively lacking, it is proposed that the southern Dabieshan belt in the Early Middle Jurassic period, the southeastern part of the southwest than the uplifted; compared with the Dabie Mountains The foothills of the gravel and debris, then that the northern uplift of the Dabie Mountains erosion faster, and violent. The collision between two sections of orogenic-volcanic island arcs and the source of the oceanic material of the sub-orogenic belt indicates the tectonic framework of the north-south trench-island arc and basin. The paleo-stress analysis based on the faults and scratches produced by the two places shows that the Late Jurassic in the study area was squeezed near the north-south direction of the Yanshan main curtain. Another near-east-west crushing stress of the Tongcheng Tractor River may indicate that the southeastern part of the Dabie Mountains had been rebuilt by the Paleo-Pacific Ocean during this period.