What is supergene enrichment in copper deposits?
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 do copper deposits undergo secondary enrichment?
Copper sulfates are reduced to copper sulphides which precipitate out as they are insoluble. These secondary copper sulphides form a concentrated small volume of high grade ‘secondary’ copper core, known as an enriched deposit. The high-grade enriched deposit overlies the lower grade primary deposit at depth.
How is a supergene formed?
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 are hypogene and supergene ore deposits?
In ore deposit geology, hypogene processes occur deep below the earth’s surface, and tend to form deposits of primary minerals, as opposed to supergene processes that occur at or near the surface, and tend to form secondary minerals.
What is the zone of oxidation?
a zone found near the earth’s surface that forms as a result of chemical decomposition of unstable minerals under the action of surface waters and groundwater, as well as the oxygen and carbon dioxide present in the air and dissolved in these waters.
What is secondary enrichment quizlet?
secondary enrichment. occurs when metals are leached from surface rocks and precipitated just below the water table.
Where is chalcocite found?
Chalcocite is sometimes found as a primary vein mineral in hydrothermal veins. However, most chalcocite occurs in the supergene enriched environment below the oxidation zone of copper deposits as a result of the leaching of copper from the oxidized minerals. It is also often found in sedimentary rocks.
What is supergene Mineralisation?
A mineral deposition process in which near-surface oxidation produces acidic solutions that leach metals, carry them downward, and reprecipitate them, thus enriching sulfide minerals already present.
What is hypogene zone?
Hypogene is a term used only in the adjective form for any geological process genetically connected with deeper parts of the Earth’s crust or for mineral, rock and ore formed beneath the surface of the Earth. The hypogene or primary ore zone underlies the supergene or secondary sulfide zone.
How do minerals accumulate in placers and what are two examples of such minerals?
How do minerals accumulate in placers, and what are two examples of such minerals? Certain heavy minerals, such as cassiterite and gold, are mechanically concentrated by currents due to their specific gravities. These concentrations are called placer deposits.
Where does supergene enrichment occur in an ore deposit?
Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary.
Why do we need pyrite for supergene enrichment?
Ideally, enrichment requires a sulfide assemblage that contains more pyrite than copper sulfides, because the pyrite is the primary source for the acid required for their development. Page 2 of 5 The moderately to strongly fractured nature of these zones also permit the movement of supergene solutions downward through these zones.
Which is the best description of a supergene process?
In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering.
How big is the enrichment blanket in copper?
Enrichment blankets at many porphyry copper deposits form large laterally extensive zones (up to 30-40 square miles) that typically range from 200 to 1,000 feet in thickness, but thin laterally to 10 to 100 feet. The enrichment blanket at the Chuquicamata deposit in Chile is reported to attain a thicknesses of up to 2,500 feet.