Heizhushan Pb-Zn-Ag-barite deposit, Lenghu Co., Mangnai City (Mangya Co.), Haixi Mongol and Tibetan Autonomous Prefecture, Qinghai, Chinai

Regional Level Types
Heizhushan Pb-Zn-Ag-barite deposit	Deposit
Lenghu Co.	County
Mangnai City (Mangya Co.)	County
Haixi Mongol and Tibetan Autonomous Prefecture	Prefecture
Qinghai	Province
China	Country

Collectively, the Heizhushan deposit shares numerous geological, geochemical, and mineralization features diagnostic of SEDEX deposits. The exposed stratigraphic succession comprises the Ordovician-Silurian Tanjianshan Group (OST), Upper Devonian Heishangou Formation (D3hs), and Quaternary unconsolidated sediments. The Ordovician-Silurian Tanjianshan Group consists of three lithological units in ascending order: Unit a is dominated by andesite with minor altered basalt; Unit b is primarily composed of siliceous rocks; Unit c mainly contains andesite, basalt, altered tuff with subordinate volcanic breccia.
The orebody occurs as a lenticular body within slates, with the central portion being thicker and tapering toward both ends. The orebody shows conformable contacts with both the underlying chloritized slate and the overlying carbonaceous slate. The orebody has a dip direction of 198°–203° and a dip angle of 51°–73°. Its thickness ranges between 0.72 m and 28.57 m, averaging 12.47 m. The total tonnage of lead–zinc-silver-barite ore amounts to 4.48 Mt, with average grades of 57.93 % BaSO4, 1.94 % Pb, 1.70 % Zn, and 43.67 g/t Ag. The Heizhushan deposit is characterized by sulfide-bearing barite ore as the dominant mineralization type. The ores occur as disseminated, laminated, veinlet and stockwork structures, and exhibit textures of fine-grained, coarse-grained, framboid, and replacement.
The mineralization stages were defined according to mineral assemblages, textural characteristics, and cross-cutting relationships, summarized as follows: Stage I involved the deposition of early-stage barite, fine-grained pyrite, sphalerite, and galena. Stage II is characterized by the formation of laminated coarse-grained pyrite, sphalerite, galena, and chalcopyrite through barite replacement. Stage III features veinlet and stockwork coarse-grained galena and sphalerite formed by replacing both barite and calcite, with the sulfides distinctly crosscutting stage I mineralization. Stage IV featured minor sphalerite and barite deposited as cavity fillings within breccias, which clearly cut across stage III mineralization.

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References