新疆东昆仑祁漫塔格地区上三叠统火山岩的年代及构造环境研究

CHRONOLOGY AND TECTONIC SETTINGS OF UPPER TRIASSIC VOLCANIC ROCKS IN THE QIMANTAGE AREA OF EAST KUNLUN OROGENIC BELT, XINJIANG

新疆东昆仑祁漫塔格地区分布着一套上三叠统、喷发韵律明显的陆相火山岩和火山碎屑岩 ,它们起源于地下深部富集稀土元素的异常地幔 ,经历了一次从基性—中性—酸性的岩浆连续演化过程。它们是东昆仑构造演化转折期的产物 ,形成于 2 10Ma～ 2 2 0Ma。

A series of Upper Triassic volcanic rocks with obvious eruptive rhythm are extensively distributed in south Qimantage area in east Kunlun orogenic belt. Two Rb-Sr whole-rock isochronal ages of 208±4 Ma have been yielded from the volcanic rocks characterized by the enrichment of light REE. With the increasing of SiO2, Eu intends to have negative anomaly obviously. Based on petrology and geochemistry, it is proposed that the volcanic series derived from the anomalous mantle rich in REE, and experienced the evolution from basic magma, neutral magma to acidic magma.