川西金口河新元古代辉绿岩的时代、成因及构造意义  

Geochronology,Petrogenesis,and Tectonic Significance of the Neoproterozoic Diabases in the Jinkouhe Area,Western Sichuan Province

作　　者：刘龙宇 崔晓庄 陈风霖 龙训荣[1] 马志鑫 孙志明 LIU LongYu;CUI XiaoZhuang;CHEN FengLin;LONG XunRong;MA ZhiXin;SUN ZhiMing(College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China;Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610218,China)

机构地区：[1]成都理工大学地球与行星科学学院,成都610059 [2]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610218

出　　处：《沉积学报》2024年第6期1890-1902,共13页Acta Sedimentologica Sinica

基　　金：中国地质调查局项目(DD20243477);国家自然科学基金项目(41872120)。

摘　　要：【目的】川西金口河地区出露大量新元古代辉绿岩脉,蕴含扬子克拉通西缘构造演化的重要信息,对理解扬子克拉通早期演化与Rodinia超大陆聚散的关系具有重要意义。【方法】对金口河辉绿岩进行了SHRIMP锆石U-Pb年代学和全岩地球化学分析。【结果】金口河地区侵入峨边群辉绿岩的锆石U-Pb年龄为823.5±9.6 Ma(MSWD=1.3,n=10)。金口河辉绿岩属于拉斑玄武岩系列,显示一定程度的Nb-Ta亏损和Eu负异常,兼具岛弧玄武岩和板内玄武岩的地球化学特征。【结论】金口河辉绿岩可能起源于浅层尖晶石—石榴石二辉橄榄岩的部分熔融,其原始岩浆遭受了俯冲熔体的交代。综合区域相关地质资料,推测其很可能形成于后碰撞伸展环境,与Rodinia超大陆聚合背景下扬子克拉通的最终拼合形成有关。[Objective]An extensive suite of Neoproterozoic diabase dykes is exposed in the Jinkouhe area of western Sichuan province,offering crucial insights into the tectonic evolution of the western Yangtze Craton.These diabases bear key implications for understanding the early tectono-magmatic history of the Yangtze Craton and its relationship with the assembly and fragmentation of the Rodinia supercontinent.[Methods]Sensitive High-Resolution Ion MicroProbe(SHRIMP)zircon U-Pb geochronology and whole-rock geochemistry analyses were performed on the Jinkouhe diabases.[Results]SHRIMP zircon U-Pb dating of the diabase samples yields an age of 823±10 Ma(MSWD=1.30,n=10).The diabases are classified as a tholeiitic basalt series,displaying Nb-Ta depletion and negative Eu anomalies.Their geochemical signatures are indicative of both island arc and intraplate basaltic affinities.[Conclusions]The Jinkouhe diabases are interpreted to have originated from partial melting of a spinel-garnet lherzolite mantle source,which was metasomatized by subduction-related melts.Combined with regional geological data,these diabases were most likely formed within a post-collisional extensional setting,reflecting tectonic processes associated with the final amalgamation of the Yangtze Craton within the context of the Rodinia supercontinent assembly.

关 键 词：新元古代 辉绿岩 地球化学 地幔源区 构造环境 

分 类 号：P597[天文地球—地球化学]