Volcanogenic Massive Sulphide–Oxide Gold Deposits of the Nubian Shield in Northeast Africa

2016 ◽  
pp. 417-435 ◽  
Author(s):  
C. Tucker Barrie ◽  
Mohamed Abu Fatima Abdalla ◽  
R. Daniel Hamer
Keyword(s):  
Gold Deposits ◽  
Massive Sulphide ◽  
Volcanogenic Massive Sulphide ◽  
Nubian Shield ◽  
Northeast Africa

scholarly journals Gold and gold-bearing volcanogenic massive sulphide deposits of the Central Cuba

2021 ◽  
pp. 27-37
Author(s):  
D. De la Nuez Colon ◽  
M. Santa Cruz Pacheco
Keyword(s):  
Gold Deposits ◽  
Massive Sulphide ◽  
The West ◽  
Massive Sulphide Deposits ◽  
Volcanogenic Massive Sulphide ◽  
Vms Deposits ◽  
Gold Silver ◽  
San Fernando ◽  
Copper Zinc ◽  
Sulphide Deposits

Background. Volcanogenic massive sulphide deposits (VMS) are the most important sources of Cu and Zn; they account for a large share of the world production of Pb, Ag, Au, Se, Te, Bi and Sb, as well as small amounts of many other metals. The polymetallic VMS deposits of economic value of varying degrees are known in the rocks of the Los Pasos Cretaceous Formation, Cuba.Aim. To show the potential of the Cretaceous volcanic deposits of Central Cuba for gold, silver, copper, zinc and lead deposit prospecting.Materials and methods. The study characterises the San Fernando, Independencia, Antonio, Los Cerros VMS deposits and the Boca del Toro and El Sol ore occurrences located in the Los Pasos Formation. The similarities and differences in the mineral and elemental composition and structures of the ores of these objects are described, which underlie the assessment of their economic importance.Results. The latitudinal zoning of VMS and noble metal mineralisation of the Central Cuban ore region is outlined. In the west, copper-VMS deposits with accompanying gold ore objects prevail. In the east, copper-zinc VMS deposits with barite and gold-silver objects are widespread.Conclusions. It is necessary to assume the different erosional sections corresponding to the blocks of the Cretaceous volcanic arc of Central Cuba, which is larger in the west and smaller in the east. Proceeding from the presence of veinlet gold ores, their confinement to tectonic zones and the lack of correlation between noble and chalcophile metals at the San Fernando deposit, as well as significantly different gold-silver ratios in the considered ore objects, it could be assumed that some of the gold-silver ores were formed after VMS. The obtained Au/Ag ratios are close to the ores of the high sulphidation type (high sulphide ores) from similar ore regions of Venezuela and the Kur-il island arc. In this regard, one can expect hidden gold deposits in the west and gold-silver deposits in the east of the studied area.

Volcanic reconstruction of Paleoproterozoic arc volcanoes: the Hidden and Louis formations, Flin Flon, Manitoba, CanadaThis is a companion paper to DeWolfe, Y.M., Gibson, H.L., and Piercey, S.J. 2009. Petrogenesis of the 1.9 Ga mafic hanging wall sequence to the Flin Flon, Callinan, and Triple 7 massive sulphide deposits, Flin Flon, Manitoba, Canada. Canadian Journal of Earth Sciences, 46: this issue.

2009 ◽  
Vol 46 (7) ◽  
pp. 481-508 ◽  
Author(s):  
Y. M. DeWolfe ◽  
H. L. Gibson ◽  
B. Lafrance ◽  
A. H. Bailes
Keyword(s):  
Hanging Wall ◽  
Massive Sulphide ◽  
Gradual Change ◽  
Shield Volcano ◽  
Ore Formation ◽  
Massive Sulphide Deposits ◽  
Volcanogenic Massive Sulphide ◽  
Volcaniclastic Rocks ◽  
Flin Flon ◽  
Sulphide Deposits

The hanging wall to the Flin Flon, Callinan, and Triple 7 volcanogenic massive sulphide deposits of the Flin Flon district is composed of the Hidden and Louis formations. The contact between these formations is marked by mafic tuff that represents a hiatus in effusive volcanism. The formations form a composite volcanic edifice that was erupted and grew within a large, volcanic–tectonic subsidence structure (hosting the deposits) that developed within a rifted-arc environment. The formations are evidence of resurgent effusive volcanism and subsidence following a hiatus in volcanism marked by ore formation since they consist of dominantly basaltic flows, sills, and volcaniclastic rocks with subordinate basaltic andesite and rhyodacitic flows and volcaniclastic rocks. The Hidden formation is interpreted to represent a small shield volcano and the Louis formation a separate shield volcano that developed on its flank. Both the Hidden and Louis volcanic edifices were constructed by continuous, low-volume eruptions of pillow lava. A gradual change from a dominantly extensional environment during the formation of the footwall Flin Flon formation to a progressively more dominant convergent environment during the emplacement of the hanging wall suggests that the Hidden and Louis formations are unlikely to host significant volcanogenic massive sulphide-type mineralization. However, synvolcanic structures in the formations define structural corridors that project downwards into the footwall where they encompass massive sulphide mineralization, indicating their control on ore formation, longevity,and reactivation as magma and fluid pathways during the growth of the Hidden and Louis volcanoes.

scholarly journals The Coulon deposit: quantifying alteration in volcanogenic massive sulphide systems modified by amphibolite-facies metamorphism

2016 ◽  
Vol 53 (12) ◽  
pp. 1443-1457 ◽  
Author(s):  
Lucie Mathieu ◽  
Rose-Anne Bouchard ◽  
Vital Pearson ◽  
Réal Daigneault
Keyword(s):  
Mass Balance ◽  
Massive Sulphide ◽  
Amphibolite Facies ◽  
High Grade ◽  
Bay Area ◽  
Volcanogenic Massive Sulphide ◽  
High Grade Metamorphism ◽  
And Performance ◽  
Superior Craton ◽  
Ore Zones

The Coulon deposit is a volcanogenic massive sulphide (VMS) system in the James Bay area, Superior craton, Quebec, that was metamorphosed to amphibolite-facies conditions. The chemistry and mineralogy of the VMS-related alteration halo proximal to the mineralized sulphide lenses are investigated, using samples collected in the field and 5583 chemical analyses provided by Osisko Ltd. Alteration is quantified using mass balance and normative calculations, and the application and performance of these methods in an exploration context are investigated. In VMS systems, altered rocks proximal to the ore zones are characterized by multi-element metasomatism, which is best quantified by mass balance methods that have been successfully applied in the study area. However, mass balance calculations necessitate the documentation of a precursor, which is not always possible in an exploration context; therefore, an alternative method (i.e., alteration indices) was also evaluated. In most VMS systems, proximal alteration is characterized by chlorite (chloritization), muscovite (sericitization), and quartz (silicification), while at the Coulon deposit, altered rocks contain mostly cordierite, biotite, sillimanite, and quartz. Alteration indices were calculated using observed and normative minerals, and provide satisfactory results similar to those obtained with mass balance calculations. Using these results, recommendations are made to estimate the intensity of alteration in the core shack using the proportions of observed minerals. Alteration indices are sensitive to the composition of precursors; and because of high-grade metamorphism, chloritization and sericitization are not precisely quantified. Recognizing these limitations is essential to successful quantification of alteration in areas metamorphosed to high-grade conditions.

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