摘要
以出露于石鼓-黎明地区的黑云母石英片岩及其深熔脉体为重点研究对象,对其中的锆石进行了阴极发光图像分析、SHRIMP和LA-ICP-MS U-Pb年代学研究。阴极发光图像显示,黑云母石英片岩中大部分锆石保留清晰的振荡环带;深熔脉体中大部分锆石具有核-边结构,核部保留清晰的振荡环带或呈灰色无分带结构,边部较窄呈黑色。对黑云母石英片岩及其深熔脉体中锆石核部进行定年,得到年龄范围为2637~743 Ma,具有858~852 Ma的主要年龄峰值,表明其主要物质来源为扬子板块西缘新元古代岩浆岩,同时也有太古代-古元古代基底岩石的加入,沉积时代应晚于852 Ma。深熔脉体锆石边部的Th/U值较小(<0.1),得到206Pb/238U年龄变化于225~197 Ma之间,可能代表了变沉积岩的变质-深熔时代,该年龄与金沙江-点苍山-哀牢山变质带二叠纪-三叠纪变质事件的时代相一致。
Based on cathodoluminescence(CL)images,the authors present LA-ICP-MS and SHRIMP U-Pb zircon data of biotite-quartz schist and granitic leucosomes in the Shigu-Liming area.Most zircon grains separated from biotite-quartz schist show clear oscillatory zoning,and most of them from granitic leucosomes are characterized by core-rim structure with strongly or weakly oscillatory zoned cores and narrow black rims.Analysis of zircon cores from biotite-quartz schist and granitic leucosomes yielded U-Pb ages of 2637~743 Ma with age peak at 858~852 Ma,indicating that their sediments were mainly transported from Neoproterozoic magmatic rocks of western Yangtze Block and also from Archean to Paleoproterozoic basement rocks and deposited after^852 Ma.These zircon rims have low Th/U ratios(<0.1)indicating the timing of anatexis.U-Pb analysis spots yielded ages of 225~197 Ma,and this age population is completely consistent with the age range of the Permian-Triassic metamorphic events of Jinshajiang-Diancangshan-Ailaoshan complex.
作者
王舫
刘福来
刘平华
蔡佳
施建荣
冀磊
刘利双
WANG Fang;LIU Fu-lai;LIU Ping-hua;CAI Jia;SHI Jian-rong;JI Lei;LIU Li-shuang(Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China;Tianjin Center,China Geological Survey,Tianjin 300170,China)
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2019年第6期881-896,共16页
Acta Petrologica et Mineralogica
基金
国家自然基金资助项目(41772193,91855206)
国家重点研发计划资助项目(2016YFC0600310)
自然资源部深地动力学重点实验室自主研究课题(J1901-8)~~
关键词
石鼓杂岩
变沉积岩
黑云母石英片岩
深熔脉体
锆石U-PB年代学
Shigu complex
meta-sedimentary rocks
biotite-quartz schist
granitic leucosomes
U-Pb zircon geochronology
