Jiaodong area is the only Late Mesozoic giant gold province hosted in a Precambrian metamorphic terrane in the world.The metallogenic system of Jiaodong gold province is unique with the following distinctive features:(1)It is situated in an intracontinental composite tectonic setting which has experienced multiple tectono-thermal events.The large-scale gold mineralization is controlled by the change of the subduction direction of the Paleo-Pacific plate and induced the asthenosphere upwelling,the modification of the lithospheric mantle,the transition of the tectonic regime from compression to transpression,and the transition of ore-controlling faults from transpression to transtension regime at 120±2Ma.(2)Multiple ore-controlling structures and diverse ore-hosting formations collectively control the development of gold deposits with various scales and types,which result in the formation of six NE-trending gold belts,namely Sanshandao,Jiaojia,Zhaoping,Qixia,Guoji and Muru,together with an EW-trending gold-rich corridor,namely Sanshandao-Qixia.These belts give rise to different mineralization types of gold deposits(Jiaojia-type/altered rock type in fractured zones,Linglong-type/quartz vein type,Pengjiakuang-type/altered conglomerate±breccia type,Liaoshang-type/pyrite-carbonate vein type),and each exhibiting distinct geological-geochemical characteristics.(3)The main mineralized elements of the belt include Au,Ag,Cu,Pb and Zn,all of which meet the requirements of industrial utilization.Furthermore,it is an area with super-enrichment of many coexisting critical metals.(4)The Pb isotopic composition of gold-bearing sulfides in different gold belts is linearly correlated to the proven gold reserves and the distance to the Tanlu fault zone,suggesting that the proximity to the main channel of mantle-derived fluids leads to the more radiogenic Pb content and mantle-derived components in sulfides and higher gold mineralization intensity.(5)The △199 Hg value(averaged at～0.012‰)is relatively uniform in the region,and the negative correlation between △199Hg/△201 Hg and the gold grade indicate that its ore-forming fluids is derived from the metasomatic lithospheric mantle,and the intensity of mantle metasomatism by subducted oceanic slab and its overlying sediments controls the gold grade.(6)The constant △33S isotopic composition(～0‰)of gold-bearing pyrites excludes the Archean metamorphic basement and its remelting granite as the initial gold source.The heavy δ34S(averaged at 9.0±3.7％o)is attributed to the devolatilization of the subducted Paleo-Pacific plate and its overlying sediments.The △33 S/δ34 S of different gold belts is linearly correlated to the known gold reserves and their distance to the Tanlu fault zone,reflecting that the degree of crustal extension during the mineralization period controls the gold mineralization intensity.(7)The regional He-Ar and H-O isotope compositions show the characteristics of crust-mantle mixing.The isotopic compositions of ore-forming fluids of the Jiaojia-type gold deposits resemble mantle value,while those of the Linglong-type gold deposits are distributed in the transition zone between mantle and crust.The Sanshandao,Jiaojia and Zhaoping gold belts exhibit fluid isotopic compositions similar to mantle-derived fluids,whereas the Guoji gold belt has a relatively open tectonic environment.Hydrogen-oxygen isotope composition positively correlates with the known gold reserves,suggesting a gradual decrease in ore-forming fluid flux and fluid-rock reaction intensity from west to east.Based on these findings,we propose a genetic model for Jiaodong-type gold deposits and clarify the key factors for the formation of the metallogenic system,such as the metallogenic geodynamic background and deep driving force,the source of giant gold and fluids and metal complexes,the channel and mode of transport,the process and mechanism of source-to-sink,the post-mineralization changes and preservation.The exploration idea of'detachment fault system and basement activation zone and mantle-derived fluid channel composite ore-controlling'and a'four-step'exploration model are established.The identification characteristics of different scales of Jiaodong gold deposits and the key factors of its formation are different from other types of gold deposits in the world.It is difficult to be explained by the existing metallogenic model.Thus,it belongs to a new type of gold deposit:The Jiaodong type.Its genetic model is universal for gold deposits in North China,South China,Siberia,the Yilgarn block of western Australia,Wyoming of South America,and Guyana of South America.Numerous prospecting breakthroughs validate the rationality and applicability of the genetic model and the proposed exploration model.The Jiaodong-type gold deposits emerge as a significant research focus and exploration direction,with disseminated gold deposits being the primary exploration target in Jiaodong area due to their large resources and stable occurrence.
Geological-geochemical features of the depositsMetallogenic systemSpatio-temporalMetallogenetic dynamicsOre-controlling factorsGenetic and exploration modelJiaodong-type gold deposits
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