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[Display omitted] • The Woxi deposit is featured by coenriched Au-Sb-W elemental association. • The Au, Sb, and W occurred mainly as invisible gold, stibnite, and scheelite. • Transition of fluid-rock interaction to phase separation caused ore precipitation. • Dissolution-reprecipitation process facilitate coenriched Au-Sb-W metallogenesis. It is well-known that tungsten and antimony are commonly enriched in the gold deposit and occur as Au-Sb or Au-W deposits. However, the Woxi deposit, located in the West Jiangnan Orogen of South China, is remarkably co-enriched in the Au-Sb-W elemental association. This deposit is characterized by multistage Au mineralization and reactivation of structures developed in the Neoproterozoic metamorphic rocks, but the detailed mechanism of its co-enriched Au-Sb-W metallogeny is still unclear. Here, we perform detailed petrographic observations and ore mineral textural and pyrite compositional analyses by using SEM and LA-ICP-MS to constrain ore-forming physiochemical conditions and to decipher the Au-Sb-W metallogenic mechanism in the Woxi deposit. The Woxi deposit consists of nine auriferous quartz lodes in the shape of stratiform, tabular, and lenticular, which are surrounded by alteration halos in the Neoproterozoic slate. These orebodies are distributed along the bedding-parallel fracture zones of the EW-striking and N -dipping in the purplish red slate of the Madiyi Formation, below the regional EW-striking Woxi fault. Four stages of hydrothermal mineralization and alteration processes could be recognized in the Woxi. Stage 1 occurs in bleached slate, and consists of euhedral, porous, and coarse auriferous pyrite (Py1), with slight arsenopyrite, siderite, and rutile. Stage 2 mainly consists of subhedral to euhedral and compositional zoning auriferous pyrite (Py2) and scheelite (Sch1), with slight wolframite and apatite hosted in quartz veinlets and native gold enclaved in Sch1. Stage 3 is characterized by scheelite (Sch2) and stibnite, with slight native gold and dendritic-shaped anhedral auriferous pyrite (Py3) hosted in quartz veins. Stage 4 features a quartz-calcite-barite-chlorite mineral assemblage that occurred as veinlets, or in the pressure shadows of Py1. Gold is mainly incorporated in the three stages (S1 to S3) of arsenian pyrite (Py1to Py3) as invisible gold and, to a lesser extent, formed visible native gold at late S2 and S3, tungsten mineralization occurs mainly as scheelite (Sch1) and wolframite at S2, with a minor amount of scheelite (Sch2) at S3, and antimony mineralization is mainly occurred as stibnite at S3. Furthermore, invisible gold most likely occurs as nanoscale particles of Au-Bi-Pb-bearing tellurides in Py1, and may be hosted in the structurally bounded lattice of Py2 and Py3.The SEM study presents highly developed dissolution-reprecipitation microstructures in hydrothermal minerals, such as pyrite, arsenopyrite, wolframite, scheelite, and apatite. Mineral paragenesis and pyrite trace element signatures suggest the ore fluid is characterized by elevated f O2 , low pH and high temperature in S1, decreased f O2 , medium pH and medium temperature in S2, and elevated f O2 , high pH and low temperature in S3. The evolution of the physicochemical condition may be induced by penetration of multipulse ore-forming fluids and the transition of the ore-forming mechanism from fluid-rock interaction in S1 and early S2 to phase separation in late S2 and S3, as suggested by textural and LA-ICP-MS analyses. This study highlighted that coupled dissolution-reprecipitation reactions might facilitate the association of the Au-Sb-W elemental that successively mineralized and co-enriched in the Woxi deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Woxi deposit is an orogenic Au-Sb-W deposit. • U-Pb dating on apatite and wolframite yielded a robust gold mineralization age of ca. 141 Ma. • Pyrite in situ S-Pb isotopic signatures suggest the ore-forming metals and fluids mainly derived from a metasomatized lithospheric mantle. • This study provides a new example of orogenic gold deposit that was controlled by translithospheric processes in a back-arc environment far from the plate subduction zone. The majority of gold mineralization in the Jiangnan Orogenic Belt (JOB) of South China share similarities with the orogenic type, but the nature of mineralization remains controversial, especially in terms of intracrustal versus subcrustal origin of ore fluids and metals and their relationships with the subduction of the Paleo-Pacific plate. This paper reports results of in situ analyses of minerals closely related to gold mineralization, including U-Pb ages of apatite and wolframite, and S-Pb isotopes of pyrite, from the Woxi Au-Sb-W deposit in the western Jiangnan Orogen, and use them to address the above problems. The Woxi deposit, which consists of several auriferous quartz lodes hosted by ductile–brittle shear zones in the Neoproterozoic slate. The hydrothermal mineralization and alteration processes are divided into four stages. Early-ore stage (S1) is characterized by disseminated, euhedral, porous, coarse auriferous pyrite (Py1) with minor amounts of arsenopyrite, siderite, and rutile in the bleached slate. Main-ore stage (S2) is characterized by subhedral to euhedral, auriferous pyrite (Py2) with compositional zoning, with small amounts of wolframite and apatite in quartz veinlets. Late-ore stage (S3) is represented by scheelite and stibnite with minor amounts of native gold and anhedral, dendritic auriferous pyrite (Py3) in quartz veinlets. Post-ore stage (S4) features a quartz-calcite-barite-chlorite mineral assemblage that occurs as veinlets or in pressure shadows of Py1. Apatite and wolframite associated with Py2 yield a consistent U-Pb age of ca. 141 Ma, which is corresponded to a time when the Paleo-Pacific plate started to roll back, and a Basin-and-Range style tectonic regime began to developing in South China. The different stages of pyrite have variable S isotopes, with the δ34S CDT values (mainly between −6‰ and +1 ‰) largely overlapping with those of the metasomatized mantle (−5‰ ∼ + 5 ‰), and Pb isotope ratios between crustal and mantle values. Taking these results together, we proposed that the Woxi deposit and many other gold deposits in the JOB formed from subcrustal processes involving the metasomatized upper mantle above the subduction zone. Given the extended distance from JOB to the Paleo-Pacific plate boundary, the metasomatized mantle underneath the JOB is likely initially formed during the plate subduction leading to the formation of the JOB during the Neoproterozoic, which is further fertilized by upwelling asthenosphere due to rollback of the Paleo-Pacific plate in the Mesozoic. [ABSTRACT FROM AUTHOR]