汉南杂岩高桥沟花岗斑岩体岩石地球化学特征及侵位机制时代归属探讨

Petrological Characteristics and Emplacement Mechanism of the Gaoqiaogou Granitic Porphyry in the Hannan Complex:A Geochemistry Approach

高桥沟花岗斑岩体位于扬子板块北缘,属于汉南杂岩的一部分。锆石LA-MCP-MS U-Pb定年结果显示其形成时代为(794.4±5.7)Ma,为南华纪早期。岩石地球化学特征为高Si(75.78%~76.51%)、富碱(K_(2)O+Na_(2)O=7.78%~7.84%)、富K(K_(2)O/Na_(2)O=1.07~1.10),属高钾钙碱性系列。稀土总量∑REE为272.57×10^(-6),轻重稀土元素组之间分馏明显。二长花岗斑岩形成于岩浆演化中晚期阶段,岩浆上侵过程中部分熔融沉积岩、火山岩物质。高桥沟花岗斑岩体形成于后造山构造环境,强力就位的侵位机制。

Gaoqiaogou granite porphyry is a part of Hannan Complex,which is located in the northern margin of the Yangtze plate.LA−MCP−MS U−Pb dating of Zircon indicates that the Zircon was formed at(794.4±5.7)Ma in the early South China epoch.The Rock Geochemistry is characterized by high silicon(75.78%~76.51%),high alkali(K_(2)O+Na_(2)O=7.78%~7.84%),high potassium(K_(2)O/Na_(2)O=1.07~1.10),high potassium calcium alkaline series,total rare earth elementsΣREE=272.57×10^(-6),and obvious fractionation between light and heavy rare earth elements.The monzonitic granite porphyry was formed in the middle and late stage of magmatic evolution.The material of partial melting sedimentary rock and volcanic rock in the process of magma intrusion.The Gaoqiaogou granite porphyry was formed in the post-orogenic tectonic environment and emplaced strongly.