Report Example on Volcanic Massive Sulphide

Introduction

Most of Canada's copper, zinc, plume, silver and gold extracted is mined from submarine volcano-related (SMV) massive sulphide (MSV) reservoirs. Examples include the Flin Flon deposits on the boundary between Manitoba and Saskatchewan. Volcanic-massive sulphide deposits are produced in the ocean-floor hydrothermal winds mostly in the subduction-zone volcanoes from the water emitted at a high-temperature within a 250° to 300°C range (DeWolfe, Gibson, and Piercey 510). The atmosphere is similar to contemporary black smokers, who form the source of water from the seabed that is rich in heat and sulphide. They are referred to as substantial deposits of sulphide, as these are typically found at very high concentrations of sulphide minerals (including sphalerite (ZnS), pyrite (FeS2), calcopyrite (CuFeS2) and galena (PBS)) (mainly in the rock). It is drained from the rocks of the oceans by moving groundwater induced by volcanic heat and rapidly precipitated into the cold seawater, causing rapid cooling and chemical alteration (Lafrance et al. 877). In the same location and the same time as the deposition of the minerals of ore the volcanic rock hosting, the deposits are produced. This paper analyzes the deposits of VMS at the Flin Flon belt.

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Geologic Setting

The greenstone belt Paleoproterozoic Flin Flon is a collage of oceanic terranes juxtaposed during ca. s 1.88 to 1.87 Ga. This happened during the arc-arc collision stages between Ga and Superior Arched Cratons and Archean Hearne, Sask. 1.84 to 1.80 Ga Trans-Hudson orogeny. The volcanic island arc is 1.90 to 1.88 Ga, arch and seafloor joints, stitched by 1.87 to 1.85 Ga, and covered by 1.85, 1.83 Ga, and 1.85, Ga, fly and molasse, respectively. The Flin Flon greenstone belt includes the Amisk collage and the arc of the Snow Lake assemblies from the west to the east. Flin Flon Mining District, based on geochemical analysis of the whole-rock and trace element, is situated at Amisks College (Fig. 1), which is a 70-km long, basalt-dominated volcanic, volcanic, intrusive and subordinate elsic rocks. The rocks are assigned to a fault-linked geographic juvenile arc, ocean floor and ocean plateau. The collage of Amisk is interrupted by ca 1.87 to 1,83 Ga successor, felsic plutons and arc mafia and is incompatible with the ca 1.85 Ga Missi Group, a sequence of the river- and alluvial-classical metasedimentary rocks (Lafrance et al. 878).

Genetic Model

The mining district of Flin Flon focuses on the Callinan-777 VMS Ore Scheme (85.5 Mt Flin Flon) which extends around the boundary between Saskatchewan and Manitoba. Hudbay Minerals Inc. currently owns and manages the mines in the district. Figure 1 displays the Flin Flon mining district's generalized geologic chart and lithostrational schemas. The mapping surface is underlined by the Flin Flon arc assembly that forms one of the tectonostratigrams in the western part of the collage of Amisk. The formation of the Flin Flon is composed of four mappable, informal components comprising rhyolite flows and domes, monolithic and heterolithic breccias, as well as massive pillowed basalt flows and float breccias (Devine et al. 16).

Club Lake Member

This is the oldest of Flin Flon's groups and comprises quatre principal units: heterolithic basalt and rhyolite breccia; rhyolite breccia predominant, massive aphyrian rhyolite; and feldsparphyric sparse flow to aphanitic basalt. The heterolithic basalt breccia comprises of fine grain, dark-coloured, feldspar-phyric basalt, sparsely feldspar-phyric basalt and scoric basalt and smaller quantities of large to flow banded, aphyric and aphanistic rhyolite in the corner. Clasts are usually lapilli but can reach up to 85 cm in length. Specific deposition units of tuff and tuff breccia are moderate to poorly sorted, dense to fine bedded. The most monolithic rhyolite breccia includes an excess of subangular, aphyric, aphanitic rhyolites, thinner, aphyric, slender basalt in a thin grain matrix. The length of the clasts is up to 52 cm. Individual units are clast supported, range in thickness from 0,5 to 2,7 m and are modest to well classified in size (Devine et al. 16).

Millrock Member

The highest member in the Flin Flon formation overlaps the previously deposited foot walled strata without alignment except in compliance with local norms. This is assumed to be a result of the swift tilting of the underlying strata when the Millrock member is situated, and erosion due to channelled mass flows is localized. Millrock is the site of the depository of Flin Flon, Callinan and 777 VMS, from heterolithic, monolithic footprints, aphyric rhyolite and quartz-feldspar and contemporary volcanic rocks. On top of the member, the bedded tuff unit consists of small, locally coloured sulphide beds of ash-size material. While the tuff is planar mainly, it is laminated locally with soft-sediment structures. The matrix will contain smaller concentrations of feldspar and quartz crystals 1-2 mm in size. It includes locally scoriaceous basalt, aphyric rhyolite, and feldspar-phyric basalt clasts. Monolithic and coherent rhyolite with quartz crystals of 3 to 5 mm, varies from comprehensive to flux banded to in situ bruised. The jigsaw suit collisions are angular to subangular in the breccia and do not seem to be transmitted. The scale is from lapilli stone and blocky breccia for Monolithic rhyolite breccias (Galley, Bailes, and Tourigny 15).

Blue Lagoon Member

This member overrides the Club Lake and is a distinct entity of various concentrations and sizes of feldspar crystals which can be 5 to 25% and which range in size from 0.2 to 1 cm. It comprises a range of subsidiary forms of rock, including rhyolites, heterolithic lithical basaltic breccia, and massive, pillowed felt spar phyric basalt flow and breccia flow. The rhyolite tuff is small to a medium-sized planar unit of less than 5% quartz crystals up to 3 mm in height. Crystalline tufa, crystal lapilli tuff, crystal lapilli stone, tufts and crystal-rich block breccia are part of the heterolithic basaltic volcanic plastic breccia units. Individual units have normal to reverse size classification, the mainly supported matrix (approx. 70 per cent matrix), poorly sorted, and 0.1 to 8.2 m thick. Although most beds have a matrix rich in feldspar, some intermixed beds have little or no feldspar in the matrix (Devine et al. 16).

Creighton Member

The interaction between the Creighton member and Blue Lagoon member is seen in the tailings pond's island, with the latter underlying the former. On the southeast, the contact relationship seems to be reversed, suggesting the two Members' contemporary deposition. The member of Creighton quickly waxes south to the dominant footwall lithology underneath the Flin Flon reservoir where it includes a basalt previously referred to as the Southern Main. It consists of basalt and ameboid breccias, aphyric flows and sills of basalt. The latter consists of scaly, aphyre basalt clasts with 40 per cent amygdules, and a sparsely-sorted basalt clasp with 10 to 20 per cent amygdals, which are supported by clasps and are moderate to poorly sorts by tuff-breccia units. Clasts range from 25 to 95 cm, with distinctive chilled margins and irregular and ameboid shapes, which are well preserved (Devine et al. 16).

Classification

The VMS along the Flin-Flon is classified under Cu-Zn deposits. The deposits present include the Besshi and Cyprus types. These types are accordant ironsulphidepacked bodies commonly underlain by stringer ore in volcanic sequences dominated by mafic volcanic rocks with locally important felsic volcanic or sedimentary rocks (Ordonez-Calderón et al. 40).

Alteration and Characteristics

The vast majority of deposits of VHMS are distinguished by quartz, chlorite, white mica (sericite), and pyrite-dominated alteration assemblages, and their metamorphosed counterparts. Alteration zones expand into semi-conforming, deep, proximal zones, which typically pipe-like, and contain, besides these minerals, epidote and albite is a common mineral. Some minerals are related explicitly to magmatic-hydrothermal ore deposits in alterations areas, e.g., porphyry Cu and skarn deposits). Still, the magmatic-hydrothermal involvement does not consider them to be diagnostic. This is because it can form by the contact between marine water and rock, as heated in a hydrothermal convective system (Huston et al. 476)

The nature and the scale of alteration halos in hanging stratigraphy of massive-sulphide deposits constitute one of the most important and least-known facets of VMS metallogeny. The continuity of hydrothermal activities following lava bury or argillaceous hydrothermal sediments (e.g. sustained exhalations of low temperature in decline stages of oral development at depth) will cause a hanging wall alteration (Galley, Bailes, and Tourigny 11). This definition has been strengthened by the Horne VMS studies which have shown that where economic portions of these deposits have been formed or reworked, at least the thickness of hanging-wall stratigraphy is present. Leakage of hydrothermal-fluid from the Ansil deposit was recorded at 500 m. When quantifying the extent and size of this hydrothermal leakage, it can become an excellent research method for focusing on future stratigraphical VMS hosting periods. These processes will also contribute to the creation of stacked mineral lenses (e.g. Amulets A and Noranda deposits Upper A), so the opportunity for possible findings in stratigraphy is more significant within hung-wall alterations (Ordóñez-Calderón et al. 39).

The Flin Flon hanging-wall analysis is based on extensive measurements of changes in volcanic-flow faces and the alteration features of the large sequence of massive basalt and basaltic andesite basalt in the pillowed Concealed Lake. This basalt flows directly over the Flin Flon, the Triple seven and the Callinan deposits from their rhyolite and volcaniclastic host strata. The presence of ample interpillow sediments, consisting of differing hydrothermal chert, hyaloclastic and alteration minerals, is one of the essential features of this Basalt Succession. The hydrothermal hyaloclastitis sediments form coherent interflowing units on different levels of the stratigraphy of hanging cliffs, with one of the thickest units atop the basalt of Secret Lake from Louis to Phantom Lakes. It is an excellent platform for migrating hydrothermal fluids because of the volume of the sediments in the formations and the high level of the hydrothermal shifts (11).

Conclusion

The VMS deposits, located in Flin Flon, Manitoba, are defined by an ore mineral assembly populated by sphalerite and pyrite and are small in amounts of chalcopyrites, galenas and pyrrhoitis. Silver is present in a variety of Ag-bearing (calcopyrite and freibergite–argentotonnant) sulphides and its own (acanthite) sulphides. Two populations of sphalerite (Fe-rich and Fe-poor) are defined as the main chemical elements of ore sulphides, three populations of chalcopyrites (pure, Ag-rich and Ag- and Sb-rich), and typical galena, in combination with pyrite and pyrrhotite. For sphalerite, the trace elements are mastered by Mn and Cd; for calcopyrite, Sn, Zn and Ge; and for pyrrhea, Se and Ni; and for pyrrhea, As and Co (12).