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投稿时间：2015-05-13 修订日期：2015-07-10 网络发布日期：2015-09-02
Abstract:The cratons are one of the most important geodynamic settings for ore mineralization, numerous world-class Au, Mo and REE deposits commonly form along its egdes and in its interior. However, what controls on the formation and distribution of such world-class deposits remain unclear. This paper, based on our and previous studies, discusses the processes of the early metallic refertilization and later remobilization in the Yangtze and the North China Cratons. It is well known that most cratons in the world have been stable after cratonization, but some of them (e.g., the Yangtze and the North China Cratons) have underwent early-stage (Proterozoic) lithospheric accretion and late-stage (Mesozoic-Cenozoic) significant reworking. After cratonization, subduction of oceanic lithosphere beneath the cratons would release metal-bearing (REE, Cu, and Au) CO2-rich fluids, which would intensively metasomatized the sub-continental lithosphere mantle (SCLM), led to metallic refertilization. Underplating of the subduction-related arc magmas on the base of cratonic crust would form a juvenile lower crust or magmatic cumulate zone, which was associated with Au and Cu accumulation as sulfides at the base of the crust. Such metallic refertilization along the craton edges has been preserved since the Proterozoic during prograde metamorphism, largely due to relatively stability of the cratons, while the Au-rich fluids liberated during high-grade metamorphism could be trapped as "solid capsules" in some places of the crust. During cratonic destruction and reworking, partial melting of the refertilized SCLM, triggered by upwelling of asthenosphere, produced the REE-rich carbonatites and hydrous mafic melts (e.g. lamprophyre), ascending upwards into to the upper crust. The carbonatitic melts emplaced at shallow crust rapidly exsolved highly-oxidized, REE-rich fluids, finally forming the carbonatite-associated REE deposits. The volatiles (CO2+H2O) escaping from the hydrous mafic melts at deep crust trigger remelting of sulfide-bearing Au-rich juvenile lower crust and remobilization of gold-bearing fluid capsules, leading to the formation of gold-rich magmatic systems or hydrothermal fluid systems. Porphyry Au deposits formed by fluids exsolved from gold-rich crust-derived magmas, while gold-bearing CO2-rich fluids transported along fault network systems produced quartz-vein and altered-rock type Au deposits. As results of the cratonic destruction, remelting of an ancient lower crust, caused by reactivating of translithospheric faults along cratonic edges or in the cratonic basement, produce the molybdenum-bearing magma system at the cratonic edges. This concept framework, presented here, intend to explain enormous enrichments of giant Au, Mo, and REE deposits along cratonic edges, which distinguishes from the metallogenic theories for ore systems in orogenic belts, and has potential implication for mineral exploration in similar cratons.
keywords:geology Au-Mo-REE gaint ore deposit metallogenic feature cratonic edges metallic refertilization
HOU ZengQian,ZHENG YuanChuan,GENG YuanSheng.2015.Metallic refertilization of lithosphere along cratonic edges and its control on Au, Mo and REE ore systems[J].Mineral Deposits34(4):641~674