卡拉麦里双泉金矿基性火山岩地球化学及地质意义

Geochemistry and Geological Significance of Basic Volcanic Rocks of Shuangquan Gold Mine in Karamaili Area

卡拉麦里地区赋存大量的晚古生代火山岩,记录着西伯利亚板块与哈萨克斯坦-准噶尔板块的活动。对卡拉麦里双泉金矿中基性火山岩的岩相学及岩石地球化学特征进行系统的分析,从而对该区域的大地构造环境及其意义进行探讨研究。双泉金矿基性火山岩属于过铝质、钙碱性岩石系列,岩石具富钾镁而贫钠钙的特点;其岩浆热液来源可能为下地壳或上地幔的壳幔混源岩浆。同时大离子亲石元素丰度较低,富集轻稀土元素,显著亏损高场强元素,显示出岛弧火山岩和地壳受同化混染作用的大陆与大洋板块内的岩石特征。在环境构造判别图上表现出岛弧火山岩特征,由此推测其很可能形成于受洋脊俯冲影响的弧前拉张环境之中。

There are a large number of Late Paleozoic volcanic rocks existing in Karamaili area, recording the activities of the Siberia plate and the Kazakhstan-Junggar plate. This paper systematically analyzes the lithofacies and geochemical characteristics of the basic volcanic rocks in Shuangquan gold mine of Karamaili, and discusses the geotectonic environment and its significance. The basic volcanic rocks of Shuangquan gold mine belong to the peraluminous and calc-alkaline rock series, and the rocks are rich in potassium and magnesium and are poor in sodium and calcium. The magmatic hydrothermal source may be the crust and mantle mixed magma of the lower crust or upper mantle. At the same time, the abundance of large ion lithophile elements is low, enriching light rare earth elements, and significantly depleting high field strength elements, showing the rock characteristics of the continental and oceanic plates in which island arc volcanic rocks and crust are assimilated. The characteristics of the island arc volcanic rocks are shown on the environmental structure discriminant diagram. It is speculated that it is likely to be formed in the fore-arc tension environment affected by the oceanic ridge subduction.