藏东夏雅岩体地球化学特征、锆石U-Pb年龄与成矿作用  

Geochemical characteristics and zircon U-Pb ages of the Xiaya intrusions in Eastern Tibet:constraints on the W,Pb,Zn mineralization

作　　者：徐长昊[1] 林艳海 于涛[4] 樊炳良[5] XU Chang-hao;LIN Yan-hai;YU Tao;FAN Bing-liang(Department of Geology College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources Laboratory,Xining 810012,China;Qinghai Geological Survey Institute,Xining 810012,China;College of Science,Tibet University,Lhasa 850000,China;Geothermal Geological Survey Party,Tibet Bureau of Geology and Mineral Exploration and Development,Lhasa 850000,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]青海省青藏高原北部地质过程与矿产资源重点实验室,青海西宁810012 [3]青海省地质调查院,青海西宁810012 [4]西藏大学理学院,西藏拉萨850000 [5]西藏自治区地质矿产勘查开发局地热地质大队,西藏拉萨850000

出　　处：《矿物学报》2020年第6期649-663,共15页Acta Mineralogica Sinica

基　　金：中国地质调查局项目(编号:DD20160016-21)。

摘　　要：对夏雅岩体中黑云母二长花岗岩、似斑状二长花岗岩和细粒花岗岩开展了LA-ICP-MS锆石U-Pb同位素和岩石地球化学特征研究,结果表明,夏雅岩体具有多期次活动的特征,活动时限为晚白垩世—古近纪(73.6±0.8~60.6±1.6Ma),岩石普遍亏损Ba、Nb、Sr、P、Ti等元素,相对富集Rb、Th、U等元素,既具有I型花岗岩的特征,又表现出A型花岗岩的部分特征,属于I-A型过渡特征的高分异钙碱性花岗岩。花岗质岩浆晚期高分异演化形成的富F、B流体是该区域主要的含钨流体,钨成矿作用时限为晚白垩世—古近纪(73.6~60.6 Ma),岩体对外围的Pb、Zn、Ag等矿床的形成仅提供了热能,并未提供成矿物质。夏雅岩体的形成环境经历了碰撞环境向板内环境转变的过程,这种构造环境机制的转变与澜沧江岛弧、昌都微陆块的晚造山、同碰撞构造环境向陆内裂谷转变有关。In this paper,the LA-ICP-MS zircon U-Pb isotopic ages and petrogeochemical characteristics of biotite monzogranites,porphyritic monzogranites,and fine-grained granites in the Xiaya intrusions in Eastern Tibet have been studied.The results show that the Xiaya intrusions is characterized with multi-stage intrusions in a period from Late Cretaceous to Paleogene(73.6±0.8-60.6±1.6 Ma).The intrusive rocks are generally depleted in Ba,Nb,Sr,P,Ti,etc.,but relatively enriched in Rb,Th,U,etc.,with some characteristics of I-type granite and A-type granite.They all belong to the highly differentiated calc-alkaline granite with transitional characteristics of I type and A type granites.The F and B rich fluids derived from the late-stage high differentiation evolved granitic magma are the main W-bearing fluids in this area with the time of W-mineralization limited in a period from Late Cretaceous to Paleogene(76.6-60.6 Ma).The intrusions only provide heat energy,but not ore-forming materials to the Pb,Zn,Ag mineralization in the surrounding area.The Xiaya intrusions were formed in a transitional process from the collisional environment to intraplate environment,which is related to the transformation of the Lancangjiang island arc and Changdu micro block from the late-orogenic and syn-collisional tectonic environment to the intracontinental rift environment.

关 键 词：夏雅岩体 岩石地球化学特征 锆石U-PB 岩石成因 钨成矿作用 

分 类 号：P588.121[天文地球—岩石学]