扬子板块西缘盐边群及周边岩体地质年代学新格局  

New geochronology framework of Yanbian Group and its surrounding magmatic bodies in western margin of Yangtze Block,China

作　　者：施泽进[1,2] 尹观 王勇 田亚铭 王沧[2] 李文杰[1] SHI Zejin;YIN Guan;WANG Yong;TIAN Yaming;WANG Cang;LI Wenjie(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059 [2]成都理工大学地球科学学院,成都610059

出　　处：《成都理工大学学报（自然科学版）》2021年第1期1-11,共11页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：国家自然科学基金项目(40739903,41872137)。

摘　　要：扬子板块西缘的盐边群及其周边岩体,作为前寒武纪构造岩浆活动带的核心,是观察和研究新元古代大陆壳生长的重要窗口。查明这一构造岩浆活动带内地质体的产出时代及构造岩浆活动的轨迹,是揭示新元古代大陆壳产生、发展地球动力学过程的重点环节。对盐边群及周边岩体的地质年代学研究表明:(1)区内大规模的岩浆事件集中在中元古代晚期至新元古代早期,荒田组海相玄武岩的喷发最早出现在1 122~1 038Ma B.P.;关刀山岩体早期的锆石U-Pb年龄为988±51Ma(N=6)和924±17Ma(N=9),并延续至857Ma B.P.;同德岩体的年龄主要集中在886~814Ma,峰值年龄为847.2±4.9 Ma(N=39)。(2)盐边群的渔门组和小坪组沉积时代晚于荒田组玄武岩、关刀山和同德岩浆岩体。(3)盐边群的碎屑沉积锆石与盐边群周边岩体锆石U-Pb年龄接近一致,是否存在成因关系,需进一步证实。以盐边群及其周边岩体为核心,同时向南、东、北方向延伸开展研究,核实区内主要岩浆地质体的产出时代、空间分布及物源特性,是重建扬子板块西缘新大陆壳生长及其地球动力学过程的必要前提。As the core of the Precambrian tectono-magmatic activity zone,the Yanbian Group and its surrounding magmatic rocks in the western margin of the Yangtze Block are important windows to observe and study the growth of the Neoproterozoic continental crust.It is the key link to reveal the geodynamic process of the formation and development of the Neoproterozoic continental crust and find out the time of the formation of the interior bodies and the track of the tectono-magmatic activity in this tectono-magmatic activity zone.The geochronology study of the Yanbian Group and its surrounding magmatic rocks shows that:(1)The large scale magmatic events in the area were concentrated in the late Mesoproterozoic to early Neoproterozoic,and the marine basalt of the Huangtian Formation first appeared in 1122~1038 Ma B.P.The zircon U-Pb ages of the early Guandaoshan rock mass are 988±51 Ma(N=6)and 924±17 Ma(N=9),and extend to 857 Ma B.P.The age of Tongde rock mass mainly concentrates in 886~814 Ma with the peak age of 847.2±4.9 Ma(N=39).(2)The deposition age of Yumen and Xiaoping Formations of the Yanbian Group was later than the age of Huangtian Formation basalts,and Guandaoshan and Tongde magmatic rock masses.(3)The detrital zircons of the Yanbian Group have nearly the same age as the U-Pb zircons of the magmatic rock masses around the Yanbian Group.Whether there is a genetic relationship between them needs to be further confirmed.It is a prerequisite to reconstruct the growth and geodynamic process of the new continent crust on the western margin of the Yangtze Block by taking the Yanbian Group and the surrounding magmatic rock mass as the core and extending to the south,east and north directions,at the same time to verify the generation age,spatial distribution and provenance characteristics of the major magmatic geological bodies in the area.

关 键 词：扬子板块 盐边群 岩浆岩体 原位锆石U-Pb年龄测定 地质年代学新格局 

分 类 号：P533[天文地球—古生物学与地层学] P534.3[天文地球—地质学]