阿尔泰南缘泥盆纪流纹岩的地球化学和大地构造背景  

GEOCHEMISTRY AND TECTONIC SETTING OF DEVONIAN RHYOLITES IN SOUTHERN ALTAY,XINJIANG,NORTHWEST CHINA

作　　者：丛峰[1] 唐红峰[1] 苏玉平[1] 

机构地区：[1]中国科学院地球化学研究所

出　　处：《大地构造与成矿学》2007年第3期359-364,共6页Geotectonica et Metallogenia

基　　金：国家重点基础研究发展规划项目(编号2001CB409805)

摘　　要：新疆阿尔泰南缘克朗和麦兹盆地内泥盆系康布铁堡组发育浅变质的酸性火山岩,岩相学特征和主量元素组成表明它们的原岩为流纹岩。该流纹岩具有高SiO2、较高(Na2O+K2O)、低TiO2和低CaO含量,属于亚碱性系列。稀土元素配分模式以轻稀土富集、Eu负异常强烈为特征。在不相容元素蛛网图上,流纹岩相对于洋脊花岗岩总体上富集大离子亲石元素和轻稀土元素,而明显亏损高场强元素Nb、Ta、Zr、Hf。在Nb-Y和Rb-(Y+Nb)判别图上,它们落入火山弧花岗岩区。这些结果显示,所研究的流纹岩形成于与俯冲作用密切相关的陆缘火山弧环境。本文研究结果为阿尔泰南缘在泥盆纪属于活动大陆边缘的认识提供了进一步的证据。Low-grade metamorphosed felsic volcanics within the Devonian Kangbutiebao Formation were developed along southern Altay, Xinjiang and outcropped in Kelang and Maizi basins. Their petrographic features and major element compositions indicate that the protoliths for these volcanic rocks are rhyolites. They are characterized by high SiO2, moderate （Na2O ＋ K2O） , low TiO2 and low CaO contents, symbolizing that they belong to the sub-alkaacteristics suggest that the rhyolites were formed in a continental volcanic arc that was closely related to subduction. The result from this study provides further evidence for the conclusion that the southern Altay was an active continental margin during the Devonian.

关 键 词：流纹岩 泥盆纪 克朗盆地 麦兹盆地 俯冲作用 阿尔泰 新疆 

分 类 号：P595[天文地球—地球化学] P542[天文地球—地质学]