塔里木克拉通经历过格林威尔造山运动吗?来自碎屑锆石年代学的证据  

Did Grenvillian Orogeny ever Happen in Tarim Craton?Evidence from Detrital Zircon Chronology

作　　者：易子渊 魏国齐[2] 郭召杰[1] Yi Ziyuan;Wei Guoqi;Guo Zhaojie(School of Earth and Space Sciences,Peking University,Beijing 100871,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]中国石油勘探开发研究院,北京100083

出　　处：《地球科学》2023年第4期1405-1420,共16页Earth Science

基　　金：国家重点研发计划项目(No.2019YFC0605501).

摘　　要：近年来,有学者认为塔里木克拉通经历过格林威尔期造山运动,但相关的岩浆、变质证据比较缺乏.造山事件会为附近的盆地提供大量碎屑物质,因此也会在碎屑锆石记录中有所反映.对塔西南铁克里克地区和塔东北库鲁克塔格地区新元古界的7件砂岩样品进行了碎屑锆石U-Pb定年,获得了1135组碎屑锆石年龄数据.塔西南南华系的波龙组和雨塘组均发育有冰碛岩,通过碎屑锆石记录得到其最大沉积年龄分别为693.2±3.3 Ma和642.7±4.4 Ma,由此推测波龙组形成于Sturtian冰期,而雨塘组形成于Marinoan冰期.此外,结合前人发表的数据,整理得到完整的塔里木克拉通新元古界碎屑锆石U-Pb年龄数据库.数据分析显示:碎屑锆石年龄主要分布在700~900 Ma和1800~2100 Ma两个区间内,与典型的格林威尔期造山活动的时间980~1250 Ma不符;阿克苏、库鲁克塔格和铁克里克3个露头区新元古界碎屑岩的物源区存在显著差异,表明在南华纪-震旦纪不存在全盆统一的物源,这与当时克拉通内发育大型造山带的假设不符.综上所述,通过对碎屑锆石记录的分析,认为格林威尔期的陆-陆碰撞型造山运动在塔里木克拉通的影响不显著.In recent years,it has been suggested that a Grenvillian orogenic belt developed in the Tarim Craton.However,associated magmatic and metamorphic evidence is absence.An orogeny provides massive detritus for the nearby basin,and hence would be reflected in the detrital zircon records.In this study,seven Neoproterozoic sandstone samples were obtained in the Tieklik area(Southwest Tarim)and the Quruqtagh area(Northeast Tarim),and studied through detrital zircon U-Pb dating.A total of 1135 detrital zircon age data were obtained.In the Nanhua System,there are tillites in the Bolong Formation and Yutang Formation in the Southwest Tarim.The maximum depositional ages constrained by the detrital zircon records are 693.2±3.3 Ma and 642.7±4.4 Ma,respectively.Therefore,the Bolong tillite and the Yutang tillite can be correlated with the Sturtian glaciation and the Marinoan glaciation,respectively.Besides,previously published data were integrated to form a complete detrital zircon UPb age database of the Neoproterozoic in the Tarim craton.It shows that the detrital zircon ages are mainly distributed in the ranges of 700-900 Ma and 1800-2100 Ma,which is inconsistent with the age range of 980-1250 Ma for the Grenvillian orogeny.Besides,the provenances of the Neoproterozoic clastic rocks in the three outcrop areas,i.e.,the Aksu,Quruqtagh and Tieklik areas,are significantly different.It indicates that there were more than one source regions during the Nanhua-Sinian periods,which contradicts the hypothesis of a large-scale orogen across the craton.In brief,this study concludes from the detrital zircon records that no Grenvillian collisional orogen developed in the Tarim craton.

关 键 词：塔里木克拉通 碎屑锆石 新元古界 格林威尔期造山带 构造地质学 

分 类 号：P542[天文地球—构造地质学]