The Zaidan Skarn Pb-Zn-Ag Deposit

The Zaidan skarn Pb-Zn-Ag deposit is located in the southeast part of the Arghandab-Trin metallic zone. It is associated with basic dykes and an Oligocene granite intrusion into the Upper Triassic to Jurassic carbonates, making it a calcic skarn deposit.

Skarn-type deposits are typical hydrothermal mineral deposits, where the original mineral composition of rocks is modified by hydrothermal fluids rich in lead, zinc, and associated elements.

These fluids, typically sourced from deep within the Earth's crust (Batholith Arghandab), migrate through fractures and faults, encountering host rocks along their journey. As they interact with these rocks, they initiate silicification, carbonization, and propylitic alterations at the contact of the wall rocks and intrusion fluids.

Silicification, the replacement of original minerals with silica, is a common alteration associated with lead and zinc deposits. This process often results in the formation of quartz veins and breccias, which serve as conduits for mineralizing fluids and can host significant concentrations of lead and zinc ores.

Carbonatization is another prevalent alteration observed in proximity to lead and zinc deposits. This process involves the replacement of primary carbonate minerals with secondary carbonate minerals, such as calcite and dolomite, which can serve as important hosts for lead and zinc mineralization.

Furthermore, sulfidation alterations, where sulfur-bearing minerals like pyrite and sphalerite replace pre-existing minerals, play a crucial role in concentrating lead and zinc ores. These sulfide minerals often form disseminated or massive sulfide bodies within the altered rock matrix.


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