What is the difference between VMS and SEDEX deposits?

VMS deposits are typically massive lens-shaped bodies, underlain by discordant vein mineralization and altered volcanic rocks. SEDEX deposits are finely layered massive sulfides interbedded with shale, siltstone, or sandstone, typical of deep marine turbidites.

What disseminated sulphides?

When it consists of clots or patches of sulphides in the country rocks, it is termed “disseminated”. The proportion of sulphide minerals, and therefore the metal grades, are generally higher in the former. However, it is not uncommon for disseminated sulphides to be sufficiently concentrated to achieve ore grades.

What is SedEx ore deposits?

Sedimentary exhalative deposits (SEDEX or SedEx deposits) are zinc-lead deposits originally interpreted to have been formed by discharge of metal-bearing basinal fluids onto the seafloor resulting in the precipitation of mainly stratiform ore, often with thin laminations of sulphide minerals.

How are SedEx deposits formed?

SedEx, or sedimentary exhalative deposits, are ore deposits formed when hydrothermal fluids enter a water reservoir, such as an ocean, and precipitate minerals. SedEx deposits are a major source of minerals including copper, silver , gold and tungsten – and the single most important source of lead and zinc .

How do VMS deposits form?

Over time, the continual activity of the smokers and their mineral rich plumes create mineralized beds that become VMS deposits. With the movement of the Earth’s tectonic plates, these mineral rich beds are transposed and can be found on land that was once underwater.

How is Sedex formed?

The term Sedex, or “sedimentary exhalative,” is a generic name that reflects the current understanding of the genesis of these deposits as having formed by the precipitation of sulfides from hydrothermal fluids vented or “exhaled” on to the seafloor.

What is SedEx type of deposit?

Which ore minerals might be found in SedEx deposits?

What does skarn look like?

Skarns or tactites are hard, coarse-grained metamorphic rocks that form by a process called metasomatism. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals.

What is Kuroko type deposit?

The Kuroko deposits of Japan are predominantly massive, stratiform sulphide ores with associated underlying stockwork ores of Miocene age in the Green Tuff volcanic sequences.

What are massive sulphides?

They consist of sulphur compounds, sulphides, which form massive deposits on the sea floor similar to cobalt crusts – thus the name. Massive sulphides originate at hot vents in the ocean where sulphide-enriched water flows out of the seabed. These sites of escaping hot water are called hydrothermal vents.

What is hydrothermal mineralization?

Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth’s crust through fractures. They eventually create metallic-rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals.

Is the bedrock source of a mineral VMS mineralization?

The trace element chemistry of indicator minerals may be useful for establishing that the bedrock source of the mineral is VMS mineralization (e.g., gahnite: Heimann et al., 2005; O’Brien et al., 2015; magnetite: Makvandi et al., 2016 ).

What is volcanic-hosted mineralization?

Volcanic-hosted or Volcanogenic base- and precious-metal mineralization is typically hosted by, or associated with, submarine volcanic and/or volcaniclastic rocks. Although volcanogenic rocks are generally the host, unrelated sedimentary marine rocks may be present.

What is the geologic origin of VMS?

In the geological past, the majority of VMS deposits were formed in rift environments associated with volcanic rocks. In particular, they formed throughout geological time associated with mid-ocean ridge spreading centres, back-arc spreading centres, and forearc spreading centres.

What is the mineralogy of VMS massive sulfide?

The mineralogy of VMS massive sulfide consists of over 90% iron sulfide, mainly in the form of pyrite, with chalcopyrite, sphalerite and galena also being major constituents. Magnetite is present in minor amounts; as magnetite content increases, the ores grade into massive oxide deposits.