四川盆地及周缘地区早三叠世富锂绿豆岩的岩浆作用制约  

The magmatic constraint for Early Triassic lithium-rich green bean rocks in Sichuan Basin and adjacent area

作　　者：王坤明[1] 王宗起 张英利[1] 马收先[1] 陈雷[1] 许光 WANG KunMing;WANG ZongQi;ZHANG YingLi;MA ShouXian;CHEN Lei;XU Guang(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China;Development and Research Center,China Geological Survey,Beijing 100037,China;Technical Guidance Center for Mineral Exploration,Ministry of Natural Resources,Beijing 100037,China;China Geological Survey,Beijing 100037,China)

机构地区：[1]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质调查局发展研究中心,北京100037 [3]自然资源部矿产勘查技术指导中心,北京100037 [4]中国地质调查局,北京100037

出　　处：《岩石学报》2023年第7期2167-2184,共18页Acta Petrologica Sinica

基　　金：深地资源勘查开采项目(2019YFC0605200);中国地质调查局地质调查项目(DD20230291、DD20230034);中国地质科学院矿产资源研究所基本科研业务费项目(KK2216);国家自然科学青年基金项目(41602061)联合资助.

摘　　要：四川盆地及周缘地区早-中三叠世地层发育大量富锂绿豆岩,前人系统开展过大量矿物学及年代学研究,但对其中锂成矿物质来源及其富集机理等方面研究较为薄弱,区域岩浆作用与沉积型锂矿的成因关系不明。本文通过对重庆北碚绿豆岩的矿物学、岩石地球化学、锆石SHRIMP U-Pb年代学及锆石Lu-Hf同位素特征研究,并与四川盆地及周缘地区的绿豆岩进行对比,结果显示四川盆地及周缘绿豆岩层位内锂的富集规律表现为绿豆岩层的下部及中部层位锂含量明显高于上部层位的锂含量。北碚绿豆岩成岩时代为248±2Ma,源岩为流纹质英安岩/英安岩,为早三叠世火山弧岩浆作用的产物。北碚绿豆岩、四川盆地周缘绿豆岩与西南三江地区早三叠世岩浆活动具有明显的成因联系,是西南三江地区火山岩浆活动在四川盆地及周缘地区的响应。四川盆地及周缘地区绿豆岩内锂富集主要与区域火山岩浆作用及后期深部流体有关,西南三江地区早三叠世中酸性火山岩浆作用为四川盆地及周缘地区绿豆岩的形成提供了充足的火山灰及部分锂成矿物质,火山灰降落之后受深部流体作用而进一步富集锂,最终经埋藏成岩作用而形成含硅质豆粒的富锂绿豆岩。The green bean rocks are rich in lithium element in Sichuan Basin and adjacent area.Many mineralogical and chronological research have been conducted,but the research of lithium element metallogenic material source and enrichment mechanism for green bean rocks are weak,and the relations between regional magmatism and lithium metallogeny are unknown.The mineral geochemistry,zircon SHRIMP U-Pb chronology and Lu-Hf isotope of Beibei green bean rocks and compare with that of green bean rocks in Sichuan Basin and adjacent area,which all indicate the lithium content show obvious higher lithium contents of the bottom of green beans rocks layer than that of the top layer in Sichuan Basin and adjacent area.The original rock for Beibei green bean rocks is rhyolite dacite/dacite,which are derived from the volcanic arc magmatism in the Early Triassic.The age of Beibei green bean rocks is 248±2Ma.The green bean rocks of Beibei and adjacent area have obvious relations with the southwestern Sanjiang area Early Triassic magmatic activity,maybe the response of Early Triassic intermediate-acidic volcanic magmatic activity of the Sanjiang area.The lithium metallogenic material source of green bean rocks in Sichuan Basin and adjacent area are related to volcanic magmatism and hydrothermal fluids.The sufficient volcanic ash and some metallogenic material source of lithium for the green bean rocks in the Sichuan Basin and adjacent area derived from the Early Triassic intermediate-acidic volcanic magmatism in southwestern Sanjiang area at an early stage,and then the volcanic ash which was modificated by hydrothermal fluid and lead to the further enrichment for lithium,and the lithium-rich green bean rocks are formed by burial diagenesis eventually.

关 键 词：绿豆岩 地质年代学 LU-HF同位素 岩浆作用 四川盆地 

分 类 号：P588.22[天文地球—岩石学] P597.3[天文地球—地质学] P618.71