摘要
对南祁连阳康地区花岗闪长岩岩体进行了锆石U-Pb年代学及岩石地球化学研究,以便对其岩石成因和中—南祁连消减拼合作用的开始时间给予制约。花岗闪长岩中LA-ICP-MS锆石U-Pb定年结果表明,该岩体形成于晚奥陶世(444±1.2 Ma,MSWD=1.14),属于高钾钙碱性系列,A/CNK值介于1.007~1.104,属弱过铝质,为I型花岗岩,并且明显富集大离子亲石元素(如K、Ba、Rb)、轻稀土元素(LREE)及Th,相对亏损高场强元素(如Ta、Nb)。上述结果表明,该类岩体的原始岩浆应起源于地壳的部分熔融。综合区域同时代火成岩的研究成果,认为花岗闪长岩岩体形成于活动大陆边缘的构造背景。
The formation age and petrogenesis of the Yangkang granites in the Qilian block remain controversial.In this study,LA-ICP-MS zircon U-Pb dating and whole-rock geochemical analysis were conducted to constrain the petrogenetic and tectonic processes during the formation of the granites.The results show that U-Pb age of granodiorite in Yangkang pluton is 444±1.2 Ma,(MSWD=1.14),indicating that it was formed in the early Late Ordovician and that the rocks belong to weak peraluminous-strong peraluminous I-type granite.The rocks are enriched with large ion lithophile elements(K,Ba,Rb) and Light Rare Earth Elements(LREEs) and Th,but depleted in the high field strength elements(e.g.,Ta-Nb).The above results show that Yangkang granites were derived from partial melting of continental crust.Combined with the regional data,the authors suggest that the Yangkang granites were probably formed in an active continental margin during Late Ordovician.
作者
方永坤
曹成刚
董峻麟
李领贵
FANG Yong-Kun;Cao Cheng-Gang;DONG Jun-Lin;LI Ling-Gui(Qinghai Environmental Geological Exploration Bureau,Xining 810000,China;No.906 Engineering Survey and Design Institute of Qinghai Province,Xining 810000,China;Key Laboratory of Environmental Geology Qinghai Province,Xining 810000,China;Qinghai Engineering Research Center of Geoenvironment Pritection and Geohazard prevention,Xining 810000,China;No.5 Geological and Mineral Survey Institute of Qinghai Province,Xining 810000,China)
出处
《物探与化探》
CAS
北大核心
2021年第6期1367-1377,共11页
Geophysical and Geochemical Exploration
基金
青海省地质勘查基金项目“青海省天峻县阳康地区J47E13011等五幅1∶5万区域地质矿产调查”(青国土资矿[2011]277)。
