新疆西昆仑温泉—独尖山一带中——下二叠统赛利亚克群火山岩地球化学特征及构造环境

Geochemical Characteristics and Tectonic Environment of Volcanic Rocks in Middlelower Permian Sailiake Group in Wenquan-Dujianshan Area in Western Kunlun in Xinjiang Uygur Autonomous Region

摘要:

新疆西昆仑温泉—独尖山一带发育中下二叠统赛利亚克群火山岩，岩石类型主要以火山熔岩、火山碎屑岩夹沉积碎屑岩为主，为一套典型岛弧火山岩建造。火山熔岩以安山岩、玄武岩、英安岩为主，岩石SiO2含量介于58.33%～64.73%，Na2O/K2O为0.93～116，样品碱度率AR从1.63～2.24，固结指数7.47～17.84，铝质指数（A/CNK）为0.73～0.98，岩石总体表现为偏铝质钠质钙碱性岩石系列特征；样品富集Th、U、Hf等元素，亏损Ba、K、Nb等，稀土元素配分曲线呈右倾型，具弱负铕异常特点，显示出岛弧火山岩的特征。通过综合分析认为，赛利亚克群火山岩形成时代为早—中二叠世，其岩浆主要来源于地幔，但有地壳物质的明显加入，形成于大陆边缘的岛弧环境。

Abstract:

The volcanic rocks in the middle-lower Permian sailyak group are developed in Wenquan-Dujianshan area in western Kunlun in Xinjiang Uygur Autonomous Region. The rock types are mainly volcanic lava, pyroclastic rock and sedimentary clastic rock. It is a set of typical island arc volcanic rock formation. Volcanic lava is dominated by andesite, basalt and dacite. The content of SiO2 in the rock is 58.33%~64.73%, Na2O/K2O is 0.93~116, the alkalinity rate AR of the sample is 1.63~2.24, the consolidation index is 7.47~17.84, and the aluminous index (A/CNK) is 0.73~0.98. The rock generally shows the characteristics of partial aluminous sodium calc alkaline rock series. The samples are enriched in Th, U, Hf and other elements and depleted in Ba, K and Nb. The REE distribution curve is right inclined with the characteristics of weak negative europium anomaly, and showing the characteristics of island arc volcanic rocks. Through comprehensive analysis, it is considered that the volcanic rocks of the sailiak group are formed in early—middle Permian, and the magma mainly come from the mantle, but with the obvious addition of crustal materials. They are formed in the island arc environment on the continental margin.