Pelitic-Mafic type Massive Sulfide Deposit
Chemical Process (Liquid-phase Growth) - Under water
Synonym
Volcanogenic massive sulfide deposit (semi-interpretative term), Stratabound massive sulfide deposit (descriptive), Stratiform massive sulfide deposit (descriptive), Volcanic-associated massive sulfide deposit (descriptive), Volcanic-hosted massive sulfide deposit (descriptive), Submarine exhalative sedimentary deposit (interpretative)
Required Geological Setting
Occurrence
A type of volcanic massive sulfide deposits associated with mafic volcanic rocks in pelitic rocks.
Host of the deposit: Mafic volcanic rocks = Siliciclastic rocks (Sedimentary rocks) >> Felsic volcanic rocks
The host of deposits is composed of mafic volcanic rocks in pelitic rocks such as shale and mudstone with few felsic volcanic rocks. The deposit is concordant with the sedimentary structure of the host, and is considered to be formed on the ocean floor of matured oceanic island arc. Pelitic-mafic type massive sulfide deposits are considered as protolith of Besshi massive sulfide deposits. Pyrrhotite-chalcopyrite-pyrite-sphalerite veins are intruded in the pelitic rocks and the mafic volcanic rocks, which are covered with massive pyrite-sphalerite blocks. Quartz and calcite are at the margin of deposits, and the whole deposit is again covered with pelitic rocks.
Mineral Assemblages (Ore)
Pyrrhotite, Chalcopyrite, Pyrite, Sphalerite, Magnetite
Mineral Assemblages (Gangue)
Quartz, Calcite