Copper hydrothermal

Dissolved Minerals. The most significant source of minerals for sustainable recovery may be ocean waters which contain nearly all the known elements in some degree of solution. Production of dissolved minerals from seawater is limited to fresh water, magnesium, magnesium compounds (qv), salt, bromine, and heavy water, ie, deuterium oxide. Considerable development of techniques for recovery of copper, gold, and uranium by solution or bacterial methods has been carried out in several countries for appHcation onshore. These methods are expected to be fully transferable to the marine environment (5). The potential for extraction of dissolved materials from naturally enriched sources, such as hydrothermal vents, may be high. 

Copper ore minerals maybe classified as primary, secondary, oxidized, and native copper. Primaryrninerals were concentrated in ore bodies by hydrothermal processes secondary minerals formed when copper sulfide deposits exposed at the surface were leached by weathering and groundwater, and the copper reprecipitated near the water table (see Metallurgy, extractive). The important copper minerals are Hsted in Table 1. Of the sulfide ores, bornite, chalcopyrite, and tetrahedrite—teimantite are primary minerals and coveUite, chalcocite, and digenite are more commonly secondary minerals. The oxide minerals, such as chrysocoUa, malachite, and azurite, were formed by oxidation of surface sulfides. Native copper is usually found in the oxidized zone. However, the principal native copper deposits in Michigan are considered primary (5). 

Almost two-thirds of the world s copper resources are porphyry deposits. The term porphyry is generally appUed to a type of disseminated copper deposit that is hydrothermal in origin and characterized by a large proportion of minerals uniformly distributed as disseminations or in fractures and small veins. Copper contents are generally 1% or less. The most extensive porphyry deposits are located in western Canada, the southwestern United States, Mexico, and western South America. In addition to the porphyrys, there are large bedded copper deposits in Germany, Poland, the CIS, AustraUa, and central Africa. 

Figure 1.170. Diagram showing the octahedral composition of chlorites from the subvolcanrc hydrothermal deposits, propylite, and Kuroko deposits in Japan (Nakamura, 1970). Chlorite occurring as a gangue mineral in the subvolcanic hydrothermal deposits Nos. 1, 2, 3 and 4 Chlorite from the Ashio copper mine. Nos. 5, 6, and 7 Chlorite from the Kishu mine. No. 8 Chlorite from the Arakawa mine. Nos. 9 and 10 Chlorite from the Ani mine. No. 11 Chlorite from the Osarizawa mine. Chlorite from the so-called propylite No. 12 Chlorite from the Yugashima mine. No. 13 Chlorite from the Budo mine. Chlorite from the Kuroko deposits No. 14 Chlorite from the Wanibuchi mine.

Mariko, T. (1984) Sub-seafloor hydrothermal alteration of basalt, diabase and the Shimokawa copper mining area, Hokkaido, Japan. Mining Geology, 34, 307-322. 

In 1986, domestic consumption of copper in the United States was 2.14 million metric tons, and mine production was 1.14 million metric tons, mostly from mines in Arizona, New Mexico, and Michigan. The major copper deposits in the United States are of hydrothermal origin and are uniformly distributed in fractures or veins (ATSDR 1990). Copper is the major toxic component in streams impacted by active placer mines (Buhl and Hamilton 1990). About 60% of copper metal is eventually recycled in 1986, smelting of scrap copper produced an additional 0.9 million metric tons of copper. Also in 1986, 1.1 million tons of copper were imported into the United States, mostly from Canada, Chile, Peru, and Mexico (ATSDR 1990). 

McCallum, I.S., Loucks, R.R., Carlson, R.R., Cooley, E.F., and Doerge, T.A., Platinum Metals Associated with Hydrothermal Copper Ores of the New Rambler Mine, Medicine Bow Mountain, Economic Geology, Vol. 71, pp. 1429-1459, 1976. 

Doe BR (1994) Zinc, copper, and lead in mid-ocean ridge basalts and the source rock control on Zn/Pb in ocean-ridge hydrothermal deposits. Geochim Cosmochim Acta 58 2215-2223 Ehrlich S, Butler I, Halicz L, Rickard D, Oldroyd A, Matthews A (submitted) Experimental study of copper isotope fractionation between aqueous Cu(II) and covellite, CuS. Chem Geol Finney LA, O Halloran TV (2003) Transition metal speciation in the cell insights from the chemistry of metal ion receptors. Science 300 931-936... 

Fulton JL, Hoffmann MM, Darab JG (2000a) An X-ray absorption fine structure study of copper(I) chloride coordination structure in water up to 325°C. Chem Phys Lett 330 300-308 Fulton JL, Hoffmann MM, Darab JG, Palmer BJ, Stem EA (2000b) Copper(I) and Copper(II) Coordination stmcture under hydrothermal conditions at 325°C An X-ray Absorption Fine Stmcture and Molecular Dynamics Study. JPhys Chem A104 11651-11663... 

Wasson JT (1985) Meteorites Their Record of Early Solar System History. New York Ereeman Wesolowski DJ, Benezeth P, Palmer DA (1998) ZnO solubility and Zrf+ complexation by chloride and sulfate in acidic solutions to 290°C with in-situ pH measurement. Geochim Cosmochim Acta 62 971-984 Wessel P, Smith WHF (1991) Free software helps map and display data. EOS Trans AGU 72 445-446 Xiao Z, Gammons CH, Williams-Jones AE (1998) Experimental study of copper(I) chloride complexing in hydrothermal solutions at 40 to 300°C and saturated water vapor pressure. Geochim Cosmochim Acta 62 2949-2964... 

As shown in Table 11.1, hydrothermal emissions are a major source of soluble iron, manganese, and zinc and a minor source of aluminum, cobalt, copper, and lead. Other elements with significant hydrothermal inputs include lithium, rubidium, cesium, and potassium. Considerable uncertainty also surroimds these flux estimates because they are the result of extrapolations from measurements made at a small number of hydrothermal systems at single points in time. These fluxes appear to vary significantly over short time scales as tectonic activity abruptly opens and closes cracks in the oceanic crust. 

Two types of metal-rich hydrogenous deposits are formed on the seafloor iron-manganese oxides and polymetallic sulfides. The iron-manganese oxides have been deposited as nodules, sediments, and crusts. They are enriched in various trace elements, such as manganese, iron, copper, cobalt, nickel, and zinc, making them a significant repository for some of these metals. Most of the metals in the polymetallic sulfides are of hydrothermal origin. These sulfides have been deposited as metalliferous sediments aroimd hydrothermal systems and as rocks that infill cracks within former... 

Trace metals, such as copper, nickel, cobalt, zinc, and various rare earth elements, tend to coprecipitate with or adsorb onto Fe-Mn oxides. As shown in Table 18.1, this causes these elements to be highly enriched in the hydrogenous deposits as compared to their concentrations in seawater. The degree of enrichment is dependent on various environmental factors, such as the redox history of the underlying sediments and hydrothermal activity. This makes the composition of the oxides geographically variable. 

Seafloor spreading eventually pushes oceanic crust into subduction zones where the hydrothermal sediments and rock are recycled back into the mantle. A small fraction of these deposits is uplifted, or obducted, onto land. These rescued deposits are termed ophiolites. Because of their metal enrichments, they serve as major ore bodies and have been mined for various precious metals, such as copper, for thousands of years. 

Although not shown in Table 19.2, hydrothermal fluids are also a significant source of copper and... 

Coats, R. 1940. Propylitization and related types of alteration on the Comstock Lode. Economic Geology, 35, 1-16 Creasey, S. C. 1959. Some phase relations in hydrothermally altered rocks of porphyry copper deposits. Economic Geology, 54, 351-373. 

Garwin, S.L. 2000. The setting, geometry and timing of intrusion-related hydrothermal systems in the vicinity of the Batu Hijau porphyry copper-gold deposit, Sumbawa, Indonesia. Unpubiished PhD thesis. University of Western Austraiia, Perth, Austraiia. 

Markl, G., Lahaye, Y., Schwinn, G. 2006. Copper isotopes as monitors of redox processes in hydrothermal mineralization. Geochimica et Cosmochimica Acta, 70(16), 4215 228. 

The major rock units in the East-Kahang are made up of andesite, volcanic breccia, dacite, quartz-diorite, diorite and locally mineralized hydrothermal breccia (Fig. 2). Eocene andesite and volcanic breccias showing propylitic alteration are the oldest units in the area. They have been intruded by dacite, mostly showing phyllic alteration associated with weak copper mineralization. Quartz-diorite and dioritic... 

The lithological and hydrothermal alteration units from the geological map of the area (1 1000 scale) are converted to an appropriate format for information synthesis. By considering the conceptual models for porphyry copper deposits and... 

Chlorine is the major anion in surface- and mantle-derived fluids. It is the most abundant anion in hydrothermal solutions and is the dominant metal complexing agent in ore forming environments (Banks et al. 2000). Despite its variable occurrence, chlorine isotope variations in natural waters conunonly are small and close to the chlorine isotope composition of the ocean. This is also true for chlorine from fluid inclusions in hydrothermal minerals which indicate no significant differences between different types of ore deposits such as Mississippi-Valley and Porphyry Copper type deposits (Eastoe et al. 1989 Eastoe and Guilbert 1992). 

This group of deposits is closely associated in space and time with magmatic intrusions that were emplaced at relatively shallow depths. They have been developed in hydrothermal systems driven by the cooling of magma (e.g., porphyry-type deposits and skams). From 8D- and 8 0-measurements, it has been concluded that porphyry copper deposits show the clearest affinity of a magmatic water imprint (Taylor 1974) with variable involvement of meteoric water generally at late stages of ore formation. 

Compared to porphyry copper deposits 5 " S-valnes in epithermal deposits are more variable due to lower temperatures of formation and significant amounts of both sulfide and sulfate in the hydrothermal flnid. 

Swaddle, T.W. Oltmann, P. (1980) Kinetics of the magnetite-maghemite-hematite transformation, with special reference to hydrothermal systems. Can. J. Chem. 58 1763-1772 Swallow, K.C. Hume, D.N. Morel, F.M.M. (1980) Sorption of copper and lead by hydrous ferric oxide. Environ. Sci. Tech. 14 1326-1331... 

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