摘要
在新疆阿牙克库木湖幅一比二十五万区域地质调查中,于东昆仑祁漫塔格山鸭子泉构造混杂岩带中发现大量以蚀变玄武岩、蚀变玄武安山岩、蚀变安山岩及蚀变辉长岩、蚀变闪长岩为主的中基性火成岩,其呈大小不一的岩片岩块存在于构造混杂岩带内。通过岩石学、岩石地球化学的研究其属钙碱性岩系的玄武岩—安山岩;具有稀土总量较低、轻稀土弱富集、重稀土分馏不明显、稀土元素配分曲线呈右倾型、大离子亲石元素富集、Nb、Ti等元素亏损的特征,显示其形成于与俯冲作用有关的岛弧环境;依据同位素测年资料和地质构造演化确定该岛弧火山岩就位于志留纪,这对东昆仑地区的地质构造演化具有重要意义。
During regionally geological investigation at a scale of 1 ： 250, 000 in the Ayakekumuhu quadrangle in Sinkiang, a lot of intermediate-basic igneous rocks has been recognized predominant in altered basalt, altered basaltic andesite, altered andesite and altered gabbro and altered diorite in the Yaziquan tectonic melange belt of Qimantage Mountain eastern Kunlun. The rocks, present as microlithon and/or blocks with different sizes, are preserved in the tectonic melange belt. Studies of the petrology and lithogeochemistry suggested that the rocks are of basalt-andesite in calc-alkaline rock succession, and are characterized by lower total content of REE, less enrichment of light rare earth, obscure fractionation of heavy rare earth, dextral partition curves of REE, enrichment of big ion lithophile element and lack of elements like Nb and Ti, indicating that the rocks formed in a island arc setting in relation to underthrust. Based on the isotopic dates and the studies of the geotectonic evolution, the island-arc volcanic rocks were suggested to be Silurian age.
出处
《陕西地质》
2005年第2期50-60,共11页
Geology of Shaanxi
基金
中国地质调查局"1:25万阿牙克库木湖幅(J45C003004)区调"项目(2000111300009271)支助
关键词
东昆仑
祁漫塔格山
岛弧火山岩
志留纪
Eastern Kunlun
Qimantage Mountain
island-arc volcanic rock
Silurian age
