西宁和贵德盆地新生代沉积物重矿物变化对构造活动的响应  

Analysis of Heavy Minerals in Sediments of Xining-Guide Basin in Northeastern Margin of the Tibet Plateau in Cenozoic Era and Its Tectonic Evolution

作　　者：孟庆泉[1] 吴小斌[1] 刘善品[1] 闫宝华[1] 吴松[1] 张洒[1] 宋春晖[1] 

机构地区：[1]兰州大学地质科学与矿产资源学院&甘肃省西部矿产资源重点实验室,兰州730000

出　　处：《沉积学报》2013年第1期139-148,共10页Acta Sedimentologica Sinica

基　　金：中国科学院战略性先导科技专项(编号:XDB03020402);国家973重点基础研究发展计划项目(编号:2013CB956400;2010CB833401);国家自然科学基金项目(批准号:41272128;40902015);国家教育部博士点基金项目(编号:20090211110021)共同资助

摘　　要：位于青藏高原东北缘的西宁、贵德盆地的新生代沉积序列较完整的记录了盆地周围物源区构造变形过程。重矿物是碎屑物质的重要组成部分,是最直观、有效揭示源区母岩、构造—沉积过程的重要手段。通过重矿物的系统分析,结合沉积—构造变形,揭示出始新世—上新世末西宁—贵得盆地及其源区经历了几个构造活动阶段:古新世—始新世早期的隆升阶段、始新世中期—渐新世晚期的构造稳定阶段、渐新世末—中新世初的构造隆升阶段、中中新世构造稳定阶段和晚中新世以来的强烈隆升阶段。并结合特征矿物(绿泥石)及古水流分析,推断古近纪西宁—贵德盆地是东昆仑山前一个统一盆地。中新世早期青藏高原的扩张导致了拉脊山开始隆起,使原型盆地解体;约8.5 Ma以来拉脊山强烈隆升,两侧盆地逐渐转变为山间盆地。这为正确理解青藏高原东北缘盆山格局的形成和演化提供了重要依据。The Cenozoic sediments of the Xining-Guide basin, locates in the northeastern margin of the Tibetan plat- eau, recorded the uplift and deformation history of northeastern plateau. The detrital heavy mineral analysis is a sensi- tive tool to deciphering these records. Five heavy mineral stages of sedimentary evolution along this region have been revealed by the heavy minerals and tectonic-sedimentary analysis： ① the earliest tectonic uplift phase between Paleo- cene and Early Eocene, ②steady stage of middle Eocene-Late Oligoeene, ③ late Oligocene-Early Miocene tectonic activity again, ④middle Miocene tectonic clam stage, ⑤stronger activity phases since Late Miocene. With the chlo- rite characteristics and the paleocurrent analysis,we suggest that the Guide-Xining was an uniform weakly flexural or rejuvenated Paleozoic foreland basin of the eastern Kunlun Mountain. The onset of deformation and rock uplift along the eastern part of the Laji Mountain, which was possibly effected by the surface uplift of the Tibetan plateau, divided the Guide and Xining basins. At about Late Miocene, the Laji Mountain began strongly deformation and surface up- lift, and the Guide and Xining basins gradually recessed. These results provide a significant evidence to thoroughly understand the formation and evolution of the NE margin of Tibet.

关 键 词：重矿物 西宁-贵德盆地 盆地演化 盆山耦合 

分 类 号：P512.2[天文地球—地质学]