摘要
马厂箐岩体属于滇西富碱侵入岩的重要组成部分,在马厂箐岩体中发现了镁铁质暗色深源包体,这对于研究滇西富碱侵入岩带的起源、演化、成岩成矿作用以及区域地球动力学机制具有重要意义。本文基于对深源包体地质特征研究,通过开展LA-ICPMSU-Pb锆石定年,得到花岗斑岩中镁铁质深源包体锆石U-Pb加权平均年龄为35.13±0.23Ma(MSWD=0.64),与其寄主岩花岗斑岩年龄(35.0±0.2Ma)和(似)斑状花岗岩年龄(33.78±0.21Ma)较为一致,结合深源包体及其寄主岩锆石的Th/U比值及Ti温度计特征,证明了包体的岩浆混合成因。分析认为:马厂箐富碱侵入岩体为壳源岩浆与幔源岩浆混合作用的产物;包体与其寄主岩具有相同或相似的岩浆演化过程;35Ma左右存在幔源岩浆的底侵注入,幔源岩浆的注入混合可能是这套岩浆成矿的关键。
Machangqing complex is an important part of alkali-rich porphyry belt in western Yunnan.The deep-derived mafic enclaves that found in Machangqing complex are significant for studying the origin and evolution of alkali-rich porphyry,ore-forming process,and regional geodynamics.According to the geological features of the enclaves,the author analyzed the zircons from enclaves with the LA-ICP-MS and obtained a U-Pb weighted average age of 35.13 ± 0.23Ma（MSWD = 0.64）.This age is consistent with the age of granite porphyry（35.0 ± 0.2Ma） and porphyritic granite（33.78 ± 0.21Ma） which are the host rocks of enclaves.The Th/U value and Ti thermometer tempetature of zircons from enclaves and host rocks suggest that the enclaves are from magma mixing.Studies show the Machangqing alkali-rich porphyry is the mixture of crust-derived and mantle-derived magma enclaves and their host rocks have the similar magma evolution process and the injection of mantle-derived magma is a key factor to the ore-formation of this series magma.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第5期1413-1424,共12页
Acta Petrologica Sinica
基金
973国家重点基础研究发展计划(2009CB421008)
武警黄金指挥部专项基金(WHY11-08)联合资助
关键词
深源包体
锆石U-PB年龄
壳-幔岩浆混合
马厂箐岩体
云南
Deep-derived enclave
Zircon U-Pb Age
Mixing of crust and mantle magma
Machangqing complex
Yunnan Province
