卡拉麦里东段下古生界的形成时代和演化  

Depositional age and evolution of early Paleozoic strata in eastern Kalamaili Tectonic Belt

作　　者：田晓莉[1,2] 李振生[2] 聂峰[2] 石永红[2] TIAN Xiaoli;LI Zhensheng;NIE Feng;SHI Yonghong(Anhui Institute of Geophysical and Geochemical Prospecting Techniques, Hefei 230022, China;School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China)

机构地区：[1]安徽省地球物理地球化学勘查技术院,安徽合肥230022 [2]合肥工业大学资源与环境工程学院,安徽合肥230009

出　　处：《合肥工业大学学报（自然科学版）》2019年第3期321-331,354,共12页Journal of Hefei University of Technology：Natural Science

基　　金：国家科技重大专项资助项目(2011ZX05008-001);国家自然科学基金资助项目(41372194)

摘　　要：文章依据卡拉麦里构造带东段下古生界中砂岩的碎屑锆石U-Pb年代学分析,重新标定东准噶尔造山带下古生界的形成时代和物源区,并约束了早古生代构造演化模式,有助于理解中亚造山带的增生和拼贴过程。测年结果显示:卡拉麦里东段原奥陶纪—志留纪地层中荒草坡群第一亚群、第二亚群和红柳峡组砂岩的碎屑锆石表面年龄特征相似,以早古生代和新元古代年龄峰为主;最年轻碎屑锆石U-Pb年龄及侵入花岗岩年龄约束荒草坡群第一亚群、第二亚群和红柳峡组的形成时代介于426～413 Ma,应为志留纪罗德洛世—普利道利世,与阿尔泰造山带哈巴河群同期。物源分析表明早古生代和前寒武纪碎屑物质分别来源于野马泉早古生代岩浆弧和准噶尔微陆块,支持准噶尔盆地存在前寒武纪大陆地壳基底。东准噶尔早古生代构造演化分为3个阶段:寒武纪—早奥陶世(523～480 Ma)阿尔曼太洋发育阶段、中奥陶世—志留纪早期(480～432 Ma)阿尔曼太洋南北双向俯冲闭合阶段和志留纪中晚期(432～416 Ma)构造转折期弧后盆地发育阶段。It is helpful to understand the accretion and amalgamation process of Central Asian Orogenic Belt(CAOB) that the depositional age and provenance of the early Paleozoic strata in eastern Kalamaili Tectonic Belt(EKTB) and the early Paleozoic tectonic evolution of eastern Junggar Orogenic Belt(EJOB) are constrained by the U-Pb chronological analysis of detrital zircons. The U-Pb dates of detrital zircons from the first and second subgroups of Huangcaopo Group and Hongliuxia Formation in EKTB are similar, and dominated by early Paleozoic and Neoproterozoic ages. The depositional ages of the first and second subgroups of Huangcaopo Group and Hongliuxia Formation, which were usually divided into Ordovician to Silurian system, are between 426 Ma and 413 Ma by the youngest U-Pb age of detrital zircons and the age of correlative intrusive granite. These strata should deposit in Ludlow to Pridoli epoch of Silurian period, and be contemporaneous with Habahe Group in the Chinese Altai Orogenic Belt. The provenance analysis shows that the early Paleozoic and Precambrian detrital materials in Silurian strata of EKTB derived from Yemaquan early Paleozoic magmatic arc and Junggar microcontinent respectively, which supports the existence of Precambrian continental crust basement in Junggar Basin. The early Paleozoic tectonic evolution of EJOB is suggested to be divided into three stages: the development stage of Aermantai ocean during Cambrian to early Ordovician(523-480 Ma), northward and southward bidirectional subduction stage of Aermantai ocean during middle Ordovician to early Silurian(480-432 Ma) and tectonic transition period with development of back-arc basin during middle and late Silurian(432-416 Ma).

关 键 词：东准噶尔 早古生代 砂岩 碎屑锆石U-Pb定年 物源分析 

分 类 号：P548[天文地球—构造地质学]