摘要
在阿吾拉勒东段玉希莫勒盖达坂地区大哈拉军山组主要是一套以安山质(粗安质)-英安质(粗面质-粗面英安质)火山熔岩和火山碎屑岩为主的火山岩建造。根据岩石地球化学特征,本文在大哈拉军山组火山岩的上部厘定出了钙碱性玄武安山岩—高钾钙碱性玄武安山岩—粗安岩(橄榄安粗岩系)组合。微量元素地球化学特征显示,三类岩石形成于岛弧环境,钙碱性玄武安山岩的形成与板片俯冲作用有关,而高钾钙碱性玄武安山岩和粗安岩的形成则与俯冲板片断裂诱发的软流圈上涌作用有关。钙碱性玄武安山岩—高钾钙碱性玄武安山岩—粗安岩组合的存在说明阿吾拉勒东段在晚石炭世由于俯冲板片的断裂,构造体制由挤压转变为伸展。玉希莫勒盖达坂大哈拉军山组上部的火山岩组合与世界许多著名铜-金矿集区(如Papua New Guinea)的火山岩组合相似,显示该地区晚石炭世具有良好的铜、金成矿条件。
Within the Yuximolegai Daban of eastern Awulale, West Tianshan, the Dahalajunshan Formation is mainly composed of andesitic (trachyandesitic)-dacitic(trachytic-trachydacitic) lavas and volcaniclastic rocks. Based on the petro-geochemical features, an association of calc-alkaline basaltic andesite-high-K calc-alkaline basaltic andesite-trachyandesite (shoshonite series) has been recognized from the upper part of volcanic rocks in the Dahalaiunshan Formation. The trace element characteristics show that three kinds of volcanic rocks were formed in the island arc environment. The generation of the calc-alkaline basaltic andesite was related to the slab subduction, while the high-K calc-alkaline basaltic andesite and trachyandesite were related to the asthenospheric upwelling induced by the subducted slab break off. The existence of this association implies that the tectonic system has been changed from compression to extension during Late Carboniferous due to the the subducted slab break off. This association is quite similar to those related to the Cu-Au mineralization in the world,for instance, that in Papua New Guinea, indicating that the Late Carboniferous has a better Cu-Au ore-forming prospect in this region.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第4期934-943,共10页
Acta Petrologica Sinica
基金
中国科学院知识创新工程重要方向项目(KZCX2-YW-107)
"十一五"国家科技支撑计划(2006BAB07BO2-03)资助
关键词
玉希莫勒盖达坂
钙碱性玄武安山岩
高钾钙碱性玄武安山岩
粗安岩
晚石炭世
Yuximolegai Daban
Calc-alkaline basaltic andesite
High-K calc-alkaline basaltic andesite
Trachyandesite
Late Carboniferous
作者简介
罗勇,男,1983年生,博士研究生,地球化学专业 牛贺才,男,1963年生,研究员,地球化学专业,E-mail:niuhc@gig.ac.cn 通讯作者:
