川西色达早侏罗世郎木寺组火山岩特征及构造意义  

Characteristics and tectonic significance of the Lower Jurassic Langmusi Formation volcanic rocks in Seda,West Sichuan,China

作　　者：曾宜君[1,2] 黄思静[1] 熊昌利[2] 冯文立[1] 

机构地区：[1]成都理工大学'油气藏地质及开发工程'国家重点实验室,610059 [2]四川省地质调查院,成都610081

出　　处：《成都理工大学学报（自然科学版）》2009年第1期78-86,共9页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国地质调查局资助项目(200313000026)

摘　　要：对四川西部色达大章乡隆湾玛日一带的火山岩进行了较系统的岩石学、地球化学研究,通过实测剖面、同位素测年及区域地层对比,将该套火山岩厘定为早侏罗世郎木寺组。该套火山岩岩石组合主要为中性、中酸性熔岩,主元素以低TiO2,高K2O和Al2O3为特征,主要为高钾钙碱性系列;稀土元素配分模式为LREE中等富集型,微量元素配分型式表现为大离子亲石元素K,Rb,Ba及高场强元素Th的富集和Ti的亏损,具有弧火山岩的特征。地质、地球化学及年代学综合分析研究结合产出特征认为,岩浆为巴颜喀拉残留洋盆闭合,陆-陆碰撞后进一步挤压环境下的产物。This article studies systematically the petrology and geochemistry of the volcanic rocks of Seda in West Sichuan. Based on the section, isotopic dating and regional strata contrasting, it determines that this suit of volcanic rocks should be the Lower Jurassic Langmusi Formation. These volcanic rocks are mainly intermediate and intermediate-acid. The chemical composition of the volcanic rocks indicates that they belong to the high-K calc-alkaline series. The volcanic rocks possess relatively high Al2 O3, K2O and comparatively low TiOe components. The chondrite-normalized REE patterns indicate that they are rich in LREE. In addition, the MORB-normalized trace element patterns are characterized by the enrichment of LILE such as K, Rb, Ba and high field strength element of Th as well as the depletion of Ti, showing the typical arc volcanic rock character. Comprehensive geological, geochemical and chronological studies and the mode of occurrence indicate that the volcanic rocks of the Langmusi Formation formed in a more extrusion environment after the Eayankala remnant ocean basin closed and the land-land collision.

关 键 词：火山岩 地球化学 早侏罗世 色达大章乡 四川西部 

分 类 号：P588.12[天文地球—岩石学]