库鲁克塔格下古生界土什布拉克组形成时代及源区：碎屑锆石U-Pb年代学证据

库鲁克塔格地区是土什布拉克组的命名地和典型剖面分布区,主要由灰绿色砂岩及粉砂岩组成。运用LA-ICP-MS U-Pb方法,对土什布拉克组3件砂岩碎屑锆石进行U-Pb年龄测定,共获得了183组U-Pb有效年龄,既限定了地层的最早形成时代,同时又获取研究区早古生代的演化资料。获得14个较年轻锆石年龄表明,土什布拉克组形成于中—晚志留世。碎屑锆石的谐和年龄表明,物源主要集中在422～537 Ma、559～999 Ma、1018～1574Ma和1604～2498Ma。碎屑锆石年龄394～537Ma和CL图像揭示,在早古生代时期发育大量岩浆岩,但目前地表仅有少量的岩浆岩记录。研究区新元古代的岩浆锆石年龄值,可能与罗迪尼亚超大陆的聚合-裂解有关。碎屑锆石也表明研究区发育区域变质作用,部分与哥伦比亚超大陆有关。

The age and provenance of the Lower Paleozoic Tushibulake Formation in Quruqtagh area: Constraints from detrital zircon U-Pb dating

The Quruqtagh area,a place which the Tushibulake Formation was named and in which typical geological sections are distributed,contains a clastic sedimentary succession consisting mainly of grayish sandstones,siltstones,tuffaceous sandstones and siltstones,and minor limestones.U-Pb ages of detrital zircons from three sandstone samples were measured using the LA-MC-ICP-MS method.183 sets of effective U-Pb ages were yielded not only to constrain the earliest stratigraphic age of the Tushibulake Formation but also to obtain evolution information of regional tectonics in Early Paleozoic.The ages of 14 young zircons indicate the Tushibulake Formation deposited in Middle to Late Silurian.The concordant ages of detrital zircons show that the sediments of Tushibulake Formation occurred mainly from 422~537 Ma,559~999 Ma,1018~1574 Ma and 1604~2498 Ma.394~537 Ma detrital zircons and CL images indicate that there occurred a large amount of magmatic rocks during Early Paleozoic,but only less amount of magmatic rock crop out.Neoproterozoic magmatic zircons in the studying area are likely related to assembly and break-up of supercontinent Rodinia.The study of detrital zircons shows that regional metamorphism developed within this area may result partially from the supercontinent Columbia.