Control of Sulfide Saturation on the Formation of Porphyry Cu-Au Deposits During Magmatic Evolution
Porphyry deposits are important sources of global copper,gold,silver,molybdenum,and other stra-tegic minerals/metals,and they are mainly distributed along convergent plate margins.Previous studies have revealed that large porphyry deposits generally originate from arc magmatism due to plate subduction,and the mineralization mostly take place at near-surface(～3-5 km).Magmatic sulfides can strongly concentrate chalcophile elements,which play important roles in metal enrichment during magmatism.Studying the enrich-ment and activation processes of chalcophile elements in sulfides is key to understanding the metallogenic mech-anism of porphyry deposits.In this paper,we systematically summarize previous studies on magmatic sulfides in porphyry deposits,investigate the controlling factors and differentiation processes of sulfide saturation,and com-pare and analyze the controls of magmatic sulfide saturation processes on metal enrichment in porphyry deposits.Magmatic sulfide saturation can be controlled by various factors such as temperature,pressure,and oxygen fu-gacity,with oxygen fugacity being the key to sulfide saturation.Sulfide saturation will promote the efficient con-centration of metals such as Cu,Au,and PGE.Particularly,PGE and Au are extremely sensitive to sulfide saturation,and slight sulfide saturation will lead to the aggregation of a large amount of PGE and Au metals.The influence of magmatic sulfide saturation on porphyry mineralization potential is controversial.Some studies conclude that sulfide saturation is the key step in porphyry mineralization because saturated sulfide promotes the concentration of metals Cu and Au.When new magma is injected or when the oxygen or sulfur fugacity of mag-ma changes,sulfide will dissolved again,causing ore-forming metals to become enriched in the silicate melt once more.Other studies conclude that sulfide saturation does not hinder porphyry mineralization during mag-matic evolution because a small amount of sulfide saturation and precipitation in the early stage will not reduce the abundance of ore-forming elements in the remaining magma,and therefore will not affect the mineralization potential.Sulfide saturation in thick crust generally occurs in the early stage,while sulfide saturation in thin crust usually occurs in the late stage.
magmatic sulfideporphyry depositchalcophile elementarc magma
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