博格达山东北缘上二叠统沉积特征与沉积演化模式

通过对博格达山东北缘西大龙口剖面与水西沟剖面上二叠统进行详细观察和精细测量,详细分析了地层特征与沉积相特征,建立了沉积演化模式。结果表明:博格达山东北缘上二叠统自下而上发育泉子街组、梧桐沟组与锅底坑组;泉子街组沉积期,西大龙口剖面与水西沟剖面分别发育冲积扇、曲流河,冲积扇砂砾岩体内有大量的砂岩砾石与油页岩砾石,为博格达山周缘地区中二叠统红雁池组与芦草沟组被剥蚀后在山前沉积的产物;梧桐沟组沉积期,博格达山隆升为物源区,西大龙口剖面与水西沟剖面分别发育辫状河、曲流河,辫状河砂砾岩体内火山岩砾石较多;锅底坑组沉积期,西大龙口剖面与水西沟剖面主要发育曲流河泛滥平原,以紫红色粉砂质泥岩、泥岩为主。

Sedimentary Characteristics and Evolution Model of the Upper Permian on the Northeast Periphery of Bogda Mountain

Through detailed outcrop observations and meticulous measurement of the Upper Permian Xidalongkou and Shuixigou profiles on the northeast periphery of Bogda Mountain, the stratigraphic and sedimentary facies characteristics of the study area were carefully analyzed, from which a sedimentary evolution model was established. The results show that, during the Upper Permian on the northeast periphery of Bogda Mountain, the Quanzijie, Wutonggou, and Guodikeng Formations developed from the bottom up. During the Quanzijie Formation deposition period, in the Xidalongkou and Shuixigou profiles, alluvial fan and meandering river sedimentary facies were developed. Inside the alluvial fan glutenite body, there is a large amount of sandstone and oil shale conglomerates, which are the product of the process whereby the Middle Permian Hongyanchi and Lucaogou Formations in the periphery of Bogda Mountain were eroded and then deposited in front of the mountain. During the Wutonggou Formation deposition period, the ancient Bogda Mountain rose up and became the main sediment source, during which, inside the Xidalongkou and Shuixigou profiles, braided river sedimentary facies and meandering river sedimentary facies were developed; more volcanic rock gravels can be found in the braided river glutenite body. During the Guodikeng Formation deposition period, the Xidalongkou and Shuixigou profiles mainly developed meandering river floodplain sedimentary facies, in which fuchsia silty mudstone and mudstone were the major depositions.