摘要
喀腊大湾地区铁矿区发育的奥陶纪火山岩主要由碱性玄武岩和拉斑玄武岩组成,碱性玄武岩具有类似OIB的地球化学特征,软流圈地幔物质参与了其熔融源区。拉斑玄武岩表现出富集LILE、Th和U,亏损HFSE和Nb-Ta,总体上表现出类似岛弧拉斑玄武岩的特征,来源于俯冲改造的岩石圈地幔,2类岩石同时出现在同一地质剖面上,共同代表了区域上早古生代弧后盆地的岩浆作用。综合区域地质资料和本文的研究结果,认为喀腊大湾地区铁矿为形成于弧后拉张环境的火山-沉积改造型矿床,成矿物质主要来源于深部地幔。
The Ordovician volcanic rocks in Kaladawan area are composed of alkali basalts and tholeiites, and the alkali basalts geo- chemically similar to OIB were derived from asthenospheric mantle. The tholeiites show enrichment of LILE,LREE and Th-U, and depletion of HFSE and Nb-Ta, similar to characteristics of island arc tholeiite, suggesting that they were derived from subduction modified lithospheric mantle. The existence of the two rock types in the same geological section implies that they jointly represented a regional early Paleozoic back-arc basin magmatism. Combining regional geological data with the authors＇ findings, it is held that the Kaladawan iron ore district is a reformed volcanic-sedimentary type deposit formed in a back-arc basin tectonic setting.
出处
《地质通报》
CAS
CSCD
北大核心
2012年第12期2070-2075,共6页
Geological Bulletin of China
基金
国家自然科学基金(编号:41002020)
陕西省自然科学基金项目(编号:2011JQ5008)
中国地质调查局地质调查项目<西昆仑-阿尔金成矿带基础地质综合研究>(编号:1212011085034)
