对滇西宝兴厂矿区复式岩体锆石进行了阴极发光(Cathodoluminescence)和激光探针等离子质谱(LA-ICP-MS)分析。结果显示锆石发育良好的振荡环带,且Th/U比值〉0.1;大部分锆石REE含量极高,且HREE富集、LREE亏损、强烈的正Ce异常和轻微的负Eu异常,是典型的花岗岩岩浆锆石。锆石Hf同位素结果显示,εHf(t)值变化于-0.4~2.7,二阶段模式年龄(TDM2)介于0.83~1.00Ga,继承锆石年龄为0.93~1.54Ga,指示显著的壳幔混合过程:印度大陆壳与欧亚大陆壳碰撞俯冲,深部地幔岩浆上涌,造成新生代-中生代基底物质部分熔融,形成以壳源为主的壳-幔混源岩浆。
Restricted by the NW Jinshajiang-Red River fault and NS Chenghai fault,Baoxingchang complex,one of alkali-rich porphyries in western Yunnan,consists of porphyritic granite,syenite porphyry,granite porphyry and alkali-feldspar granite porphyry.This study has analysed zircons in Baoxingchang complexes by cathodoluminescence and LA-ICP-MS.Cathodoluminescence(CL)images and REE analysis results of these zircons suggest that typical magmatic zircons characterized by oscillatory zoning and the Th/U ratios0.1,have high REE,considerable LREE depletion,HREE enrichment,positive Ce and Eu anomalies in chondrite-normalized REE patterns,which belongs to typical granite magmatic zircon.In addition,the Hf isotopes of zircons spaning anεHf(t)range of-0.4-2.7,and the TDM2(Hf)at an range of0.83-1.00 Ga in magmatic zircons and 0.93-1.54 Ga in inherited zircons,suggest significant crust-mantle interaction process for magma.The partial melting of Cenozioc-Mesozioc crustal basement and mantle magma upwelling along deep fracture occur as a result of collision and indentation of India into Asia,forming crust-derived magma mixed with mantle-derived magma.