中祁连北缘托来河地区石炭纪—三叠纪盆地演化研究
发布时间：2019-06-06 02:45
【摘要】：研究区位于青藏高原东北缘北祁连造山带和中祁连微陆块之间,其石炭纪—三叠纪地层之间以整合接触关系为主,主要是浅海、海陆交互相至陆相稳定型沉积建造。通过系统开展该套地层砂岩碎屑锆石U-Pb年代学、砂岩成分Dickinson图解分析,对于约束这一时期沉积物源的构造背景、恢复缝合带上叠盆地的性质、盆地沉积充填模式和古地理面貌,进而讨论与塔里木、柴达木的盆地构造演化关系方面均具有重要意义。本次研究采集到北祁连造山带南缘上二叠统红泉组、中祁连地块北缘上二叠统忠什公组和上三叠统尕勒得寺组共3件砂岩样品,分别对它们进行碎屑锆石LA-ICP-MS U-Pb测年,结果表明具有相似的年龄组成,主要包括2600-2200 Ma、1900-1300Ma、900-800Ma、500-400Ma、290-250Ma等5个年龄峰。其中2600-2200 Ma、1900-1300Ma两年龄峰锆石95颗,推测来源于自中祁连地块或华北板块结晶基底;900-800Ma年龄峰锆石11颗,很可能来源于研究区托来南山片麻状二长花岗岩岩体及周边岩体。500-400Ma年龄峰锆石37颗,来源于北祁连造山带和中祁连活动陆缘在造山期形成的岩浆岩和变质岩;290-250Ma年龄峰锆石46颗,来源于研究区已隆升且再活化的古祁连山造山带或东昆仑岛弧。石炭纪—三叠纪地层中砂岩Dickison三角图解研究表明,上石炭统羊虎沟组、下-中二叠统江河组砂岩样品具有较高的石英含量落入循环造山带;下-中二叠统大黄沟组、上二叠统红泉组样品及忠什公组样品落入切割弧区与循环造山带的边界;下-中三叠统下环仓组与江河组大部分样品落入循环造山带;上三叠统阿塔寺组、尕勒得寺组样品落入切割弧,这两套地层中相对较高的长石含量,可能是物源区的深成侵入岩已经露出地表,并为研究区的砂岩提供物质来源而造成的。最后,将区域石炭纪-三叠纪沉积古地理演化规律归纳为晚石炭世自南向北超覆、二叠纪-三叠纪向南退缩、二叠纪末向南水位逐渐加深、三叠纪接受浅海—滨海—三角洲—沼泽相连续沉积的过程。
[Abstract]:The study area is located between the northern Qilian orogenic belt and the middle Qilian microcontinent block on the northeast margin of Qinghai-Xizang Plateau. The integrated contact relationship between the Carboniferous and Triassic strata is dominated by the shallow sea, the sea-land intersection and the continental stable sedimentary formation. The study area is located between the northern Qilian orogenic belt and the middle Qilian microcontinent block on the northeast margin of Qinghai-Tibet Plateau. Through the systematic development of U-Pb chronology of sandstone clastic zircon and Dickinson graphic analysis of sandstone composition, the tectonic background of sedimentary source in this period is constrained and the properties of superimposed basins in suture zone are restored. The sedimentary filling model and paleogeographic features of the basin are of great significance in discussing the relationship with the tectonic evolution of the basin in Tarim and Chaidamu. In this study, three sandstone samples were collected from the Upper Permian Hongquan formation on the southern margin of the North Qilian orogenic belt, the Upper Permian Zhongshigong formation and the Upper Triassic Caledesi formation on the northern margin of the Middle Qilian Block. The clastic zircon LA-ICP-MS U-Pb dating was carried out respectively. the results show that they have similar age composition, including 2600 鈮，
本文编号：2494011
[Abstract]:The study area is located between the northern Qilian orogenic belt and the middle Qilian microcontinent block on the northeast margin of Qinghai-Xizang Plateau. The integrated contact relationship between the Carboniferous and Triassic strata is dominated by the shallow sea, the sea-land intersection and the continental stable sedimentary formation. The study area is located between the northern Qilian orogenic belt and the middle Qilian microcontinent block on the northeast margin of Qinghai-Tibet Plateau. Through the systematic development of U-Pb chronology of sandstone clastic zircon and Dickinson graphic analysis of sandstone composition, the tectonic background of sedimentary source in this period is constrained and the properties of superimposed basins in suture zone are restored. The sedimentary filling model and paleogeographic features of the basin are of great significance in discussing the relationship with the tectonic evolution of the basin in Tarim and Chaidamu. In this study, three sandstone samples were collected from the Upper Permian Hongquan formation on the southern margin of the North Qilian orogenic belt, the Upper Permian Zhongshigong formation and the Upper Triassic Caledesi formation on the northern margin of the Middle Qilian Block. The clastic zircon LA-ICP-MS U-Pb dating was carried out respectively. the results show that they have similar age composition, including 2600 鈮，
本文编号：2494011
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