Abstract:The major role played by pre-existing structures in the formation of vein-style mineral deposits is demonstrated with several examples. The control of a pre-existing decollement level on the formation of a crustal extension-related (collapse) gold deposit is first illustrated in the Quadrilátero Ferrífero from Brazil. Shear zone and decollement structures were also examined and shown to control veins formation by three distinct processes: (i) re-aperture and re-using of wrench shear zones in the case of Shila … Show more
“…10ac). Hence the cleavage serves as a receptacle for chalcopyrite concentration in a late deformation event that causes dilation parallel to a pre-existing cleavage (Chauvet et al 2019). The evidence clearly supports the pyrrhotite-rich mineralization as being overprinted and further remobilized by syn-to late-tectonic pyrite-and chalcopyrite-rich mineralization.…”
Section: Deformation Of the Mineralized Lensesmentioning
The manuscript will undergo copyediting, typesetting and correction before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the book series pertain. Although reasonable efforts have been made to obtain all necessary permissions from third parties to include their copyrighted content within this article, their full citation and copyright line may not be present in this Accepted Manuscript version. Before using any content from this article, please refer to the Version of Record once published for full citation and copyright details, as permissions may be required.
“…10ac). Hence the cleavage serves as a receptacle for chalcopyrite concentration in a late deformation event that causes dilation parallel to a pre-existing cleavage (Chauvet et al 2019). The evidence clearly supports the pyrrhotite-rich mineralization as being overprinted and further remobilized by syn-to late-tectonic pyrite-and chalcopyrite-rich mineralization.…”
Section: Deformation Of the Mineralized Lensesmentioning
The manuscript will undergo copyediting, typesetting and correction before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the book series pertain. Although reasonable efforts have been made to obtain all necessary permissions from third parties to include their copyrighted content within this article, their full citation and copyright line may not be present in this Accepted Manuscript version. Before using any content from this article, please refer to the Version of Record once published for full citation and copyright details, as permissions may be required.
“…In hydrothermal explosions, the rounded shape of clasts is determined by reworking (abrasion and milling) during their genesis (e.g., References [49,50] and references therein). Actually, it might have been originated also by other reworking processes, such as those related to sediment transport (e.g., fluvial transport in the subaerial environment); however, this process seems to be unlikely as the clasts show a well-preserved altered outer rim and occur at depth > 120 m.…”
Section: Implication For the Zgp Hydrothermal Systemmentioning
The Zannone Giant Pockmark (ZGP) is a shallow-water (<−150 m) giant depression located on the shelf off Zannone Island (Pontine Archipelago, central Tyrrhenian Sea, Italy), hosting active hydrothermal vents. The ZGP seabed displays different fluid-venting morphologies (pockmarks, lithified pavements, mounds, and cone-shaped structures) and widespread bacterial communities. In this study, we analyzed ROV (Remote Operated Vehicle) images to gain information on seabed geology and the textural, mineralogical, and geochemical composition of authigenic crusts and gravel-sized clasts sampled close to active emissions. ROV images show authigenic dome-shaped crusts composed of native sulfur associated with barite, gypsum, amorphous silica, and secondary hydrothermal minerals (illite–montmorillonite). The gravel-sized clasts are mostly rhyolites strongly affected by hydrothermal alteration (Alteration Index > 88; depletion of some mobile elements and enrichment of some base metals), causing feldspar-destruction, silicification, formation of hydrothermal phyllosilicates, and precipitation of disseminated pyrite. More intense alteration implying the complete obliteration of the primary mineralogy or fabric is represented by quartz-pyrite samples. ZGP seabed morphology and petro-geochemical features of deposits point to the possible occurrence of a sulfide system linked to the degassing of magma similar to that feeding the Pleistocene products of Ponza Island.
“…These publications mostly concerned vein internal infilling textures [10,11], the vein formation model, with the contribution and controversy of the crack seal, dissolution-precipitation, diffusion, and seismic-valves mechanisms (e.g., [12][13][14][15][16]). In his review, Chauvet [17] discussed of some of these concepts, in order to highlight the role and the significance of pre-existing structures in the formation of vein-style deposits.…”
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confidence: 99%
“…Funedda et al [19] and Fridovsky et al [20] also used a detailed description of the relationships between mineralization and deformation in deformed domains, such as the Variscan domain of Sardinia and the Verkhovansk-Kolyma folded region of NE Russia. Funedda et al [19] pay close attention to the opening process of structures that will serve as traps for mineralised fluid catching, a fact that is fundamental in any tectonic understanding of a mineralised vein system [17]. Fridovsky et al [20] also proposed a pluri-deformational model associated with multiple stages of mineralisation formation.…”
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confidence: 99%
“…In addition, it has been demonstrated that stockwork within VHMS environments can result in subsequent syntectonic veining instead of earlier veins related to feeder zones [31]. Indeed, the observation of stockwork within a VHMS context needs to be considered with particular attention because of the possible coexistence of the two types of stockwork: the one related to the feeder zone and the other the result of subsequent deformation [17]. It has been suggested that the second event and associated metal may contribute significantly to a relative enrichment in VHMS environment.…”
“Structural Control” remains a crucial point that is frequently absent in scientific and/or economic analyses of ore deposits, whatever their type and class, although a selection of references illustrates its importance [...]
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