陕西宁陕东江口花岗岩成因及构造环境浅析

A Brief Analysis of the Genesis and Tectonic Environment of Dongjiangkou Granite in Ningshan County, Shaanxi

摘要: 本论文以陕西宁陕东江口花岗岩为研究对象，从地质背景和地球化学角度探讨了花岗岩成因及构造环境。对东江口花岗岩研究发现：1) 东江口岩体的岩性主要为岩浆混染作用形成的过渡岩石组合，少部分为岩浆演化形成的岩石组合。2) 微量元素富集亲石元素，亏损高场强元素；富集轻稀土，亏损重稀土且轻重稀土分馏程度强烈。3) 在花岗岩判断图解中，岩石样品在Hf-Rb/10-Ta × 3图中投影到了碰撞大陆构造背景花岗岩内以及其与板内花岗岩的交界线；显然，东江口花岗岩体形成于碰撞大陆构造环境。

Abstract: In this paper, we took the Dongjiangkou granite in Ningshan County, Shaanxi as the research object to explore the genesis and tectonic environment of the granite from the perspectives of geological setting and geochemistry. The study of Dongjiangkou granite shows that: 1) The lithology of the Dongjiangkou rock mass is mainly a transitional rock assemblage formed by magmatic hybridization, and a small part is a rock assemblage formed by magmatic evolution. 2) Trace elements are enriched in lithophilic elements and high field strength elements are lost; light rare earth is enriched, heavy rare earth is depleted, and the degree of fractionation of light and heavy rare earth is strong. 3) In the granite judgment diagram, the rock samples are projected into the granite of the collision continental tectonic background and the boundary line between the granite and the intraplate granite in the Hf-Rb/10-Ta × 3 diagram. Obviously, the granite body of Dongjiang was formed in the tectonic environment of the collision continent.