西北地质2011，Vol.44Issue(4)：23-32,10.
青海鄂拉山地区陆相火山岩地球化学特征及构造环境
Geochemical Characteristics and Tectonic Environment of the Continental Facies Volcanic Rocks in Elashan Area, Qinghai Province
摘要
Abstract
Late Triassic volcanic rocks with the combination of neutral-acidic volcanic rock of magmatic belt in Elashan area, composed of the basaltic andesite, andesite, dacite, rhyolite and a little of pyroclastic rock etc. The volcanic rock altered strongly, layered poorly, columnar joints developed, which showed the typical characteristics of terrestrial eruptions. Volcanic rocks are Al saturation type, and Rittmann index (δ) and petrologic features display a calc-alkaline, (FeO/MgO) and K2O/Na2O show that the volcanic rock may have the characteristics of continental margin island arc environment. It has high degree of LREE fractionation and enrichment, δEu is less than 1, with a weak negative anomalies. It has similar curves of REE distribution patterns and island-arc curve REE patterns. The trace elements such as Rb, Ba, Th and other elements significantly enriched while Ti, Y, Yb, Sc, Cr and other elements are poor. The characteristics of Nb/Zr, La/Nb, Th/Ta, Th × Ta/Hf2 and other elements reflected that the volcanic rock in Elashan Formation was formed in the environment of continental margin volcanic arc. According to these characteristics of the regional geological setting and geochemical, structural environment of the volcanic rock, we have summarized this conclusion that late Triassic volcanic rocks in Elashan area were produced in the environment of the coexistence of East Kunlun block and West Qinling block mutually collision with continental margin arc environment.关键词
鄂拉山岩浆岩带/陆相火山岩/陆陆碰撞/陆缘弧Key words
magmatic belt in Elashan area/ continental volcanic rocks/ blocks collision/ continental margin arc分类
天文与地球科学引用本文复制引用
李永祥,李善平,王树林,王磊,商健,张志青,赵海霞..青海鄂拉山地区陆相火山岩地球化学特征及构造环境[J].西北地质,2011,44(4):23-32,10.基金项目
青海省科技计划项目(2009-G-119) （2009-G-119）
