VMS, also known as volcanic-hosted massive sulfides (VHMS) deposits, are defined as a massive accumulation of pyritic sulfides formed during discharge of hydrothermal fluids on the seafloor ("black smokers") and by replacement of reactive seafloor rocks such as shales and carbonates. The metal distribution is zoned with a decrease in Cu/(Zn + Pb) upward and outward from the base of the lens-shaped massive sulfide deposit. VMS deposits are important sources of copper, zinc, lead, gold and silver, with cobalt, tin, barium, sulfur, selenium, manganese, cadmium, indium, bismuth, tellurium, gallium and germanium as co- or by-products. VMS deposits can exhibit high metal grades with sulfide content up to 60% and are one of the more common economically exploited deposit types.
SedEx deposits are characterized by finely laminated sulfide minerals precipitated on the sea floor from exhaled hydrothermal fluids. These deposits are stratiform in nature but vary greatly in shape. They are similar to VMS but are hosted in sedimentary rocks (shales, carbonates), typically formed far from the vent source, and formed in fault-bounded, reduced sedimentary basins on continental crust rather than oceanic crush. SedEx deposits are the most important source of lead, zinc and barite (~50% of world's lead & zinc reserves) and can host economic concentrations of silver, copper, gold, bismuth and tungsten.
Porphyry Copper Deposits (PCD) are centered on a felsic to intermediate intrusive that contain disseminated sulfides with vein and veinlet-hosted silicates + sulfides. These deposits exhibit broad-scale wall-rock alteration zones formed from hydrothermal fluids in arc-related settings sourced from subduction zone magmas. PCDs are characterized by large tonnages and low grades of ore mineralization and an intrusive complexes that are surrounded by vein stockwork and hydrothermal breccias. They generally contain multiple stages of mineralizing events. Many other mineral deposit styles are associated with PCDs including: epithermal Au, carbonate replacement, and skarn deposits. PCDs represent the largest source of mined Cu and a significant portion of global Au production. The term Porphyry Copper Deposit can be misleading as there are many types including: Cu, Cu-Mo, Cu-Mo-Au, Cu-Au, Au, Mo, W-Mo, Sn, Sn-Ag and Ag.
More deposit types coming soon!