THE SBT AND GOLD-ANTIMONY MINERALIZATION, SW GUIZHOU, CHINA

The structural alteration body (abbreviated as SBT) is hosted between the Maokou Formation and the Longtan Formation / the Emeishan basalts in Southwest Guizhou. As a product of regional tectonic events and large scale low-temperature hydrothermal alterations and the place of gold and antimony deposits emplacement.

The gold-antimony deposits (the Shuiyindong, Zimudang, Nibao, Getang, Jiadi, and Damaidi gold deposits and the Dachang antimony deposit) in the region, belong to the same mineralization system with different occurrence position, have proven gold resources of hundreds of tons with greater prospecting prospects.

Metallogenic model: The SBT and the Au-Sb deposits are located at the junction between the Yangtze Plate and the Youjiang Fold Belt where the deep faults through the crust to the upper mantle were reactivated by the Yanshannian movement and provided the conduit for the transport of the Au-bearing fluid. This metalliferous fluid is thought to have been associated with the deep granites and enriched in CH₄-N₂-CO₂ , Au²⁺, Sb²⁺, Hg²⁺, As²⁺, and H₂O. The fluid migrated upward into the uncomformable interfaces (structural detachment surfaces) between P₂m and P₃l or P₂m and P₃β, and then laterally transported and interacted with the country rocks that led to the formation of the SBT. These structural detachment surfaces are not only the channels for the transport of the fluids but also the favorable spaces for Au-Sb concentrations.Some fluids flowed upward along the faults or fractures in the core of anticlines into the stratigraphic assemblage of permeable carbonates interlayered with sealed carbonaceous shale, which might form a seal cap and force fluids to laterally diffuse through porous carbonates and precipitate stratabound Au deposits such as Shuiyindong in the southwestern Guizhou Province. The remaining fluid with high contents of Sb due to Au precipitation in the SBT moved further along the unconformable boundaries until reaching another favorable closed structure like the dome of Bihenying and formed famous stratabound Sb deposits such as Dachang.