扬子西缘峨边群碎屑锆石年代学特征及其地质意义  

Detrital Zircon U-Pb Geochronology Characteristics and Geological Significance of the Ebian Group in the Western Yangtze Block

作　　者：陈风霖 王剑 崔晓庄 沈利军 李夔洲 庞维华 任飞 CHEN FengLin;WANG Jian;CUI XiaoZhuang;SHEN LiJun;LI KuiZhou;PANG WeiHua;REN Fei(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Qiangtang Institute of Sedimentary Basin,Southwest Petroleum University,Chengdu 610500,China;Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 611230,China)

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]油气藏地质与开发工程国家重点实验室(西南石油大学),成都610500 [3]西南石油大学羌塘盆地研究院,成都610500 [4]中国地质调查局成都地质调查中心(西南地质科技创新中心),成都611230

出　　处：《沉积学报》2024年第6期1936-1947,共12页Acta Sedimentologica Sinica

基　　金：中国地质调查局项目(DD20240033);国家自然科学基金项目(41972121,41872120);中国博士后科学基金项目(2022T150076)。

摘　　要：【目的】扬子西缘峨边群传统上被认为是华南中元古代晚期的代表性地层单元之一,其沉积时限与物源特征可为重建全球Rodinia超大陆汇聚背景下扬子陆块的中—新元古代构造演化过程提供重要约束。【方法】对峨边群变质碎屑沉积岩开展了岩石学和碎屑锆石U-Pb年代学分析。【结果】获得了峨边群枷担桥组两件变质细粒岩屑砂岩样品的碎屑锆石年龄区间为1950~900 Ma,主要相对概率峰值为~910 Ma、~1570和~1730 Ma,以及次要峰值为~1130 Ma、~1390 Ma、~1840 Ma、~2500 Ma和~2550 Ma。最大沉积年龄分别为908±8 Ma(MSWD=0.10,n=5)和905±5 Ma(MSWD=0.52,n=9)。【结论】结合区域已有相关资料,峨边群枷担桥组的沉积时限为~910 Ma至~860 Ma,其主要沉积物源来自扬子西缘南侧的古—中元古代岩浆岩,推测可能形成于新元古代早期微陆块拼合的构造背景,与Rodinia超大陆的全球性汇聚过程相关。[Objective]The Ebian Group in the western Yangtze Block has traditionally been regarded as a representative lithostratigraphic unit of the Late Mesoproterozoic in South China.The sedimentation age and provenance characteristics of the Ebian Group can provide important constraints for reconstructing the Meso-Neoproterozoic tectonic evolution of the Yangtze Block under the background of the assembly of the global Rodinia supercontinent.[Methods]In this study,petrological and detrital zircon U-Pb geochronological analyses were conducted on metasedimentary rocks of the Ebian Group.[Results]The detrital zircon ages of two metamorphic fine-grained litharenite sandstones from the Jiadanqiao Formation of the Ebian Group range from 1950 Ma to 900 Ma.The main relative probability peaks are ca.910,1570,and 1730 Ma,with secondary peaks at ca.1130,1390,1840,and 2500 Ma.The maximum depositional ages are 908±8 Ma(MSWD=0.10,n=5)and 905±5 Ma(MSWD=0.52,n=9),respectively.[Conclusions]Combined with regional geological data,the depositional age of the Jiadanqiao Formation of the Ebian Group is constrained as 910860 Ma.The sediment source was magmatic rocks in the western Yangtze Block,with a predominant direction towards the south.Thus,formation likely occurred during the Early Neoproterozoic micro-block assembly and can be associated with the global assembly of the Rodinia supercontinent.

关 键 词：中—新元古代 峨边群 碎屑锆石 物源分析 构造环境 

分 类 号：P597[天文地球—地球化学]