About 45％of tungsten,～20％of tin,and～9％of fluorite of known world reserves are as-sociated with Late Mesozoic igneous rocks,Southeast(SE)China.Here we demonstrate that Fogang granite,the largest inland batholith,is mainly of A2-type that is commonly found in post-orogenic set-tings and experienced plate subduction induced metasomatism.In contrast,the Yajishan syenite and Nankunshan granite intruding the Fogang granite～20 Ma later are of A1-type formed in intraplate set-tings.We found that F-rich fluid fractionation,which could make the decline of Ga/Al ratio,total(Nb+Y+Ce+Zr)and Zr concentrations,Nb/Ta and Zr/Hf ratios,leads to chemical variations of a few Fo-gang granites changing from A2-type to highly fractionated or I-and S-type granitoids.Crystal and F-rich fluid fractionations,as well as crustal contamination most likely derived from the Fogang granite,result in some Nankunshan granites developing from A1-type into A2-type.These late-or post-magmatic processes should be taken into account carefully when discriminating the petrogenetic types of igneous rocks,especially for the A2-type suites.Combining with the distribution of 180-140 Ma A1-and A2-type igneous rocks,rare metal deposits,and fluorite deposits in SE China,we highlight the significant role of slab-released F-rich fluids in formation of A-type suites and subsequent chemical differentiation and rare metal and fluorine mineralization.A model of flat-slab northeastward rollback is thus proposed,in which the subduction front reached somewhere near Fogang and then started to roll back at～165 Ma.The inland Jurassic granites of SE China represent a unique locality for formation of A-type suites and their associated mineralization.These granites are not anorogenic,but they are the result of slab roll-back from a flat slab,founding of that slab at shallow levels,and metasomatism of by F-rich fluids relat-ed to slab heating by the asthenosphere.

Xing Ding;Koulin Su;Haibo Yan;Jinlong Liang;Weidong Sun

State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;CAS Center for Excellence in Deep Earth Sciences,Guangzhou 510640,China;Geological Survey Institute of Guangzhou,Guangzhou 510640,China;Department of Geochemistry,Chengdu University of Technology,Chengdu 610059,China;Center of Deep Sea Research,Institute of Oceanography,Chinese Academy of Sciences,Qingdao 266071,China;Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237,China

地球科学学刊（英文版）

[1]Xing Ding;Koulin Su;Haibo Yan;Jinlong Liang;Weidong Sun-.Effect of F-Rich Fluids on the A-Type Magmatism and Related Metal Mobilization:New Insights from the Fogang-Nankunshan-Yajishan Igneous Rocks in Southeast China)[J].地球科学学刊（英文版）,2022(03):591-608

Magmatism,Fogang,Nankunshan,Yajishan,batholith,Nb+Y+Ce+Zr,anorogenic

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