西天山阿吾拉勒一带大哈拉军山组火山岩地球化学特征及构造环境分析

GEOCHEMICAL CHARACTERISTICS OF THE DAHALAJUNSHAN FORMATION VOLCANIC ROCKS AND THEIR IMPLICATIONS ON THE TECTONIC SETTING IN AWULALE AREA

新疆阿吾拉勒山—带大哈拉军山组火山岩是陆缘弧构造环境，通过研究，测区火山岩具高K、高Al和低碱、低Ti的特点；微量元素地球化学组成与典型火山（岛）弧环境玄武岩的地球化学组成一致；稀土总量97．89×10^-6～222．87×10^-6，平均含量为140．71×10^-6，具轻稀土亏损，重稀土富集特点；各种构造环境判别图解表明，大哈拉军山组火山岩位于靠大陆边缘的岛弧区，大哈拉军山组火山岩记录了西天山阿吾拉勒地区在早石炭世处于板块俯冲碰撞环境的重要信息。

Lower Carboniferous Dahalajunshan formation volcanic rocks are found at the continental margin arc zone in the Awulale area. The volcanic rocks have high CaO and Al2O3 and low aluminum and TiO2. Geochemical modeling of trace element shows patterns in accordance with the basaltic geochemistry pattern of the typical model environment volcano arc. The total amount of REE is 97.89～222.87× 10^-6 with an average value of 140.71 × 10^-6. The REE values show the light REE are depleted and the heavy REE are enriched. It is shown that the tectonic setting of Dahalajunshan formation volcanic rocks lies in the continental margin arc zone. The Dahalajunshan formation volcanic rocks record important information on subduction and collision of the plate in early Carboniferous in the Awulaleshan area of Western Tianshan.