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.

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 are sediment-hosted deposits?

Sediment-hosted copper deposits are formed by fluid mixing in permeable sedimentary and. (more rarely) volcanic rocks. Two fluids are involved: an oxidized brine carrying copper as. a chloride complex, and a reduced fluid, commonly formed in the presence of anaerobic. sulfate-reducing bacteria.

What is secondary enrichment?

supergene sulfide enrichment, also called Secondary Enrichment, in geology, natural upgrading of buried sulfide deposits by the secondary or subsequent deposition of metals that are dissolved as sulfates in waters percolating through the oxidized mineral zone near the surface.

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.

How are VMS deposits formed?

Distribution. 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 are vein deposits?

Veins are mineral deposits which form when a preexisting fracture or fissure within a host rock is filled with new mineral material. The deposition of minerals is typically performed by circulating aqueous solutions. Many ore deposits of economic importance occur in veins.

What disseminated deposits?

A type of mineral deposit in which the minerals occur as small particles or veinlets scattered through the country rock.

What is hypogene and supergene?

Supergene is a term used to describe near-surface processes and their products, formed at low temperature and pressure by the activity of descending water and gas. The opposite term is hypogene, formed by ascending water and gas at high temperature and pressure.

What is stratiform deposit?

In mineral deposit: Stratiform deposits. A final class of hydrothermal deposit is called stratiform because the ore minerals are always confined within specific strata and are distributed in a manner that resembles particles in a sedimentary rock.

What is Kuroko type of deposit How did this deposit form?

Kuroko deposits (Model 28a; Singer, 1986b) are typically developed in intermediate to felsic volcanic rock and are generally interpreted to have formed in extensional environments associated with arc volcanism. They are commonly high grade and can be very large.

How are copper deposits formed?

Copper is a metal that has been deposited from hot sulphur solutions, created in volcanic regions. The hot solutions concentrated the copper up to a thousand times more than would normally be found in rocks. The resultant enriched rocks are called copper ores.

How is a porphyry formed?

The porphyry deposits are formed by differentiation and cooling of a column of rising magma in stages. The different stages of cooling create porphyritic textures in intrusive as well as in subvolcanic rocks.

How are VMS mined?

Black and white smokers expel this seawater back to the surface. Black and white smokers exhale a mineral rich-plume that spreads out over the ocean floor. As it moves farther and farther away from its heat source, the plume precipitates minerals onto the ocean floor.

How are placer deposits formed?

“Placer” deposits are formed by surface weathering and ocean, river or wind action resulting in concentration of some valuable heavy resistant minerals of economic quantities. The placer can be an accumulation of valuable minerals formed by gravity separation during sedimentary processes.

How are disseminated deposits formed?

Disseminated deposits are those in which the metal is evenly distributed in generally low concentrations throughout large masses of rock. An important type of disseminated deposit is the porphyry copper deposit, in which copper and molybdenum are found in porphyritic intrusive rocks.

How do supergene deposits form?

The supergene routes of laterite formation predominantly involve periodic meteoric water circulation derived from precipitation of snow and rain. The meteoric waters flow in the weathering profile under moderate topography with concomitant oxidation and chemical weathering of preexisting ore minerals.