Adakite-like rocks and mineralization:confusion and inquiry.
Zeng Jiannian1,Xu Jifeng21.Faculty of Resources,China University of Geosciences(Wuhan),Wuhan 430074,China2.Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China
According to the variation in the components of intermediate-acid igneous rocks coming from the lower crust,it is possible to restrain the depth of the source area and the minimum thickness of the crust,and thus to provide important information for the study of the deep process of the continental intraplate mineralization.Globally,many world level porphyry copper deposits and metallogenic systems formed by hypabyssal hot liquid have their close relationship with the synchronous adakite in space-time and genesis;domestically,the adakite-like rocks have been identified to be related to the metallogenesis in the main metallogenic areas in China.The recognition of adakite-like rocks having no relationship with the process of subduction makes it possible to construct a metallogenic model of continental intraplate porphyry metal deposits by combining other geological evidences,and this model is totally different from the metallogenic model of porphyry copper deposits with B-subduction setting constructed by Sillitoe(1972).The existence of adakite-like rocks may be the necessary condition but not the sufficient one for forming the large-scale porphyry deposits and the hypabyssal hot-liquid deposits,whose metallogenic elements mainly came from the mantle.The metallogenic potential of adakite-like rocks is achieved by the entering of the mantle material,and the metallogenic specialization of adakite-like rocks is decided by the distribution characteristics of the metallogenic elements in the upper mantle.An important reason for the adakite-like magma related to subduction being advantageous to mineralization is that there were abundant high pressure and high temperature liquid coming from the subducted plate-pieces and the magma of high fO2 coming from the melting of subducted plate-pieces.However,for those adakite-like rocks,whose occurrence has continental plate background but does not relate to the subduction,their metallogenic mechanism is not clear yet.Based on the concept of modern mineral exploration and combined with the analysis of integrated geological information,we may better realize the practical prospecting significance of the adakite-like rocks.
【Fund】： 中国地质调查局资源评价项目(1212010781014);; 国家重点基础研究发展计划“973”项目(2002CB412602);; 中国科学院知识创新工程项目(KZCX3-SW-143);; 国家杰出青年基金项目(40425003)
【CateGory Index】： P611
【CateGory Index】： P611