gold and amphibolite

The Navachab gold mine in central Namibia is situated in amphibolite-facies, marble-dominated metasediments of the Neoproterozoic Damara Sequence in the Pan-African Damara Belt.

Amphibolite is a coarse-grained metamorphic rock, predominantly composed of mineral amphibole and plagioclase …

The most obvious shortcoming is in considering ore deposits found in rocks of uppermost amphibolite and granulite facies domains where temperatures were …

The greenschist-amphibolite facies transition zone within metabasites is of great importance due to the common occurrence of this transition within greenstone belts, and the proposition that fluids released across the transition may be involved in orogenic gold deposit formation.

Petrology and gold mineralization of the amphibolite belt, Ilesha area, Southwestern Nigeria. Geologie en mijnbouw, 65, p.189-195, maps, table, English résumé. International African Bibliography Online .

A syn-peak metamorphic introduction of gold (i.e. continuum) in a hydrothermal fluid would lead to in situ partial melting, rather than aqueous gold transport, given the inferred metamorphic grade (see 3 Principles of partial melting in the uppermost amphibolite and granulite facies, 4.2.1 Geological setting of the Big Bell gold deposit). …

A garnet amphibolite from the Imjingang belt in the Korean Peninsula is chosen as an example of the P-T-t estimation for metamorphic rocks with an upper amphibolite facies peak ... uranium, IOCG, porphyry, stratiform tungsten, epithermal, and gold deposits, both intrusion-related and orogenic, have also been documented (Figure 1 and Table 1 ...

It is suggested that a gold-bearing magmatic rock was metamorphosed into amphibolite and metadolerite with the subsequent partitioning of Fe-oxide, rutile and Fe-rich biotite in the gold grains ...

Among those, the La Pointe deposit has several characteristics similar to other amphibolite facies orogenic gold deposits, such as disseminated and replacement mineralization, and an alteration ...

Deposits are also found in higher-grade metamorphic rocks, known as hypozonal gold deposits. These deposits are mostly hosted in amphibolite-facies rocks in greenstone belts and are characterized by high-temperature alteration assemblages such as garnet, diopside, hornblende, and K-feldspar and ore-forming temperatures as high as …

The Marco zone is hosted by amphibolite-grade, strongly foliated volcanic rocks and consists of disseminated gold, with an apparent thickness ranging from 1.8 to 39.5 m and gold grades up to 23 g ...

The genesis of hypozonal orogenic gold deposits is highly controversial, with both crustal metamorphic fluids and variously derived sub-crustal fluids suggested as fluid and metal sources. The Lower Jurassic Danba gold deposit, a rare Phanerozoic hypozonal orogenic gold deposit on the western margin of the Yangtze Craton, China, provides an …

Archaean lode gold deposits in the Coolgardie Goldfield, Western Australia, occur in mafic and ultramafic rocks which have been metamorphosed to the amphibolite facies. Mineralisation was broadly synchronous with peak metamorphism, the main phase of granitoid emplacement, and regional deformation. Several different structural styles are …

KEYWORDS: amphibolite facies, geochronology, gold, metamorphism, migmatite Introduction 'Orogenic' gold deposits commonly form in greenschist facies terrains, and are rare in high-grade metamorphic rocks (Groves, 1993). This is conventionally attributed to gold mineralization forming from gold complexes

Our thermodynamic simulations indicate that subsolidus metamorphic devolatilization of komatiites at ~700 °C (upper amphibolite facies) can unlock …

The close spatial association of creeks containing placer gold and the gneiss, schist, amphibolite, and marble unit strongly suggests this metamorphic unit is the gold source. High terrace gravels record a time from the late Tertiary to early Pleistocene when the ancestral Fortymile River and its major tributaries, the North and South Forks ...

Abstract and Figures. A metamorphic devolatilization model can explain the enrichment, segregation, timing, distribution and character of many goldfields such as those found in Archean greenstone ...

Abstract. A significant proportion of gold production from the Archean Yilgarn craton in Western Australia has come from lode- and vein-style deposits …

The orogenic gold deposits have been subdivided into the hypozonal (>12 km), mesozonal (6 to 12 km), and epizonal (<6 km) types by Groves et al. (1998).Major features, especially the alteration and mineralization features, of representative deposits from six orogenic gold provinces with varied formation depth and gold mineralization …

To model the formation of orogenic gold deposits, in a global perspective, it is important to understand the ore-forming conditions not only for deposits hosted in greenschist facies rocks but also in amphibolite facies. The Paleoproterozoic Fäboliden deposit in northern Sweden belongs to the globally rare hypozonal group of orogenic …

Actinolite is common in the low amphibolite facies country rocks of the Roberto deposit (Fontaine et al., 2015; Table 2), and andradite is commonly associated with the gold mineralization at Big Bell, which is hosted in middle amphibolite facies country rocks (Mueller et al., 1996; Table 2). Calcium is a major element in tremolite, actinolite ...

The aims of this contribution are to determine: 1. The trace element concentration of pyrite and pyrrhotite (and to a lesser extent sphalerite, galena, and chalcopyrite) in three groups of deposits (pyrite-pyrrhotite units, Cu-Au, and Pb-Zn-Ag-(Cu-Au)) in the Kanmantoo Group to evaluate how lower to middle amphibolite facies …

Metamorphic devolatilization of pelite is a key process in sourcing fluids and metals for orogenic gold deposits. The process of extracting S, Au, As, Cu, Pb and Zn …

Type Metamorphic Rock Texture Non-foliated to weakly-foliated; Medium-grained Composition Amphibole and Plagioclase Index Minerals Amphibole Color Black Miscellaneous Salt and pepper appearance Metamorphic Type Regional Metamorphic Grade Middle Grade (Middle P – Middle T) Parent Rock Basalt; Mafic igneous rocks …

Gold deposits are rare in upper-amphibolite to granulite facies environments. Known examples commonly attract debate about whether they formed under these conditions or instead represent ...

The amphibolite, most likely grunerite, has now been largely altered to hematite, goethite and quartz and it displays a beautiful golden iridescence. Also called "Gold Leaf Stone". It occurs in the Pilbara region of Western Australia on Abydos Station approximately 120 km south of Port Hedland.

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The Qussuk gold occurrence illustrates that epithermal gold deposits existed at the Archean, and that they can be preserved up to upper amphibolite metamorphic conditions, further highlighting the ...

morphism of the migmatitic gneiss complex is in amphibolite to granulite facies grade; the schist belt which is essentially N-S to NNE-SSW trending belts and concentrated more in western half of the Nigeria is greenschist-amphibolite facies (Ajibade and Wright 1989). The rocks of the schist belt host the gold and

History. Amphibolite--sometimes also referred to as hornblende--is a metamorphic rock that contains amphibole minerals (hence its name) and feldspars. This dark and heavy rock comes in both banded and crystal forms and can contain a range of other gemstones and materials. In antiquity, amphibolite was carved into sculpture.