High-grade ore shoots at the Martha epithermal vein system, Deseado Massif, Argentina: The interplay of tectonic, hydrothermal and supergene processes in ore genesis

Páez, Gerardo Néstor; Ruiz, Remigio; Guido, Diego M.; Ríos, Francisco Javier; Pérez, Ignacio Subías; Récio, Clemente; Schalamuk, Isidoro Bernardo Abel

doi:10.1016/j.oregeorev.2015.07.026

Cited by 22 publications

(10 citation statements)

References 40 publications

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“…At this time, deposition of rhyolitic volcanic products of the Upper Section and related late geothermal features (hot spring and hydrothermal eruption breccia deposits) overprinted the earlier system. E4 could be related to this event, in which a silver-rich phase precipitated by remobilization at lower temperatures, as was observed by Páez et al (2016) at the Martha mine.…”

Section: Reconstruction Of the Volcanic And Hydrothermal Systemsmentioning

confidence: 52%

“…11 Stable isotope (δD versus δ 18 O) plot showing the isotopic ratios of Jurassic meteoric waters for the Deseado Massif (Cravero et al 1991), volcanic vapors, felsic magmas, and porphyry ores (Hedenquist and Lowenstern 1994;Taylor 1986;Giggenbach 1992), compared to calculated waters in equilibrium with adularia and clay minerals of stage 1, and calcite from stage 9, of the Marianas-San Marcos vein system. Histograms of isotopic values from the Deseado Massif epithermal deposits (Schalamuk et al 1997;Guido 2002;Moreira 2005) hydrothermal breccia crosscuts high-grade portions of the veins, the breccia register higher Ag values, suggesting mechanical and chemical remobilization of the silver (e.g., Gilligan and Marshall 1987;Marshall and Gilligan 1987;Hobbs 1987;Gu et al 2007;Páez et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Deseado Massif epithermal deposits include low to intermediate sulfidation veins, stockworks, and breccias (Guido and Schalamuk 2003;Echavarría et al 2005;Fernández et al 2008), controlled by major NW to WNW Jurassic rift structures and minor NE and E-W trending structures (Giacosa et al 2010;Páez et al 2016). The region also records several Jurassic geothermal paleosurface features, such as silica and carbonate hot spring deposits, with associated steamheated advanced argillic alteration and phreatic breccias (Schalamuk et al 1997(Schalamuk et al , 1999Guido et al 2002;Echeveste 2005;Channing et al 2007;Guido and Campbell 2011, 2012.…”

Section: Introductionmentioning

confidence: 99%

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The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au–Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

et al. 2016

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The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of similar to 6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 A degrees C fluid dominated by meteoric and volcanic waters (-3aEuro degrees to -0aEuro degrees delta O-18(water)), with < 3 % NaCl equivalent salinity and with a magmatic source of sulfur (-1 to -2 aEuro degrees delta S-34(water)). Metal was mainly precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at similar to 600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 aEuro degrees delta O-18(water)). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with measured fluid inclusion temperatures. A striking aspect of the Marianas-San Marcos vein system is that the high-grade/high-temperature veins are partially covered by breccia and volcaniclastic deposits of acidic composition, and are spatially associated with hot spring-related deposits and an advanced argillic alteration blanket. A telescoped model is therefore proposed for the Marianas-San Marcos area, where deeper veins were uplifted and eroded, and then partially covered by non-explosive, post-mineral rhyolitic domes and reworked volcaniclastic deposits, together with shallow geothermal features. The last tectonic-hydrothermal mineralization episode (E4), interpreted to have formed at lower temperatures, could be related to this late tectonic and hydrothermal activityCONICET UNLP Goldcorp Inc. mining compan

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Section: Reconstruction Of the Volcanic And Hydrothermal Systemsmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au–Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

et al. 2016

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“…• Physical segregation and accumulation (e.g., Penrose 1910;Ewers and Hudson 1972;Tomkins 2010); • Structure and intersection of fissures as well as the physical character of the wall rock that may provide preferred pathways, offer advantageous space, or trap the metalbearing solution/magma into favorable positions (e.g., Hulin 1929;Gough 1965;Stone and Archibald 2004;Páez et al 2016);…”

Section: Introductionmentioning

confidence: 99%

“…• Local mixing or influx of a further gaseous or liquid fluid into or phase separation of the ore-bearing solution/magma (e.g., Penrose 1910;Hulin 1929;Shepherd et al 1991;Markl et al 2016); • Chemical character of the wall rock (e.g., Hulin 1929;Shepherd et al 1991;Squire et al 2008;Kreissl et al 2018); • Post-depositional remobilization by alteration and/or weathering (e.g., Tomkins et al 2004;Collins et al 2012;Fougerouse et al 2016;Páez et al 2016).…”

Section: Introductionmentioning

confidence: 99%

The formation of (Ni-Co-Sb)-Ag-As ore shoots in hydrothermal galena-sphalerite-fluorite veins

et al. 2021

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Unusual hydrothermal native As-sulfide ± native Ag ± arsenide ± antimonide ± sulfosalt ore shoots and their co-genetic sulfide-fluorite-barite-quartz host veins, which are common in the region and in whole Central Europe, were investigated at three localities in the Schwarzwald, SW Germany, to understand the physico-chemical processes governing the change from a normal (= common) hydrothermal to an exceptional ore shoot regime. Based on fluid inclusions, the formation of the gangue minerals is the result of binary mixing between a NaCl-rich brine and a CaCl2-rich brine (both ~ 20 wt% NaCl aq.). This mixing correlation, major and minor fluid composition, formation temperature (~ 150 °C), and δ34S signature are identical (within error) in ore shoots and host veins. Thermodynamic modeling indicates that ore shoot formation must have resulted from a change in redox conditions by a local influx of a volumetrically minor reducing agent, probably hydrocarbons. The elemental content and the mineralogy of each ore shoot locality (Ag-As-rich: Münstertal; Ag–Ni-As-rich: Urberg; Ag–Ni-As-Sb-rich: Wieden) reflect the metal content of the binary mixed fluid, while mineral textures, successions, and assemblages are thermodynamically and, regarding sulfur, kinetically controlled. The formation of vein and ore shoot sulfides requires an addition of sulfide, most probably from the sulfide-bearing host rocks, because thermodynamic and kinetic reasons suggest that the two major vein-forming and metal-bearing fluids are not the source of the sulfur. The final ore shoot textures are influenced by later hydrothermal remobilization processes of As and Ag. This results in a number of sulfosalts, mostly proustite-pyrargyrite. Interestingly, the greater thermodynamic stability of Sb-endmember sulfosalts enables them to form even in As-dominated fluid systems.

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Supergene oxidation of epithermal gold-silver mineralization in the Deseado massif, Patagonia, Argentina: response to subduction of the Chile Ridge

Sillitoe¹

2018

Miner Deposita

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High-grade ore shoots at the Martha epithermal vein system, Deseado Massif, Argentina: The interplay of tectonic, hydrothermal and supergene processes in ore genesis

Cited by 22 publications

References 40 publications

The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au–Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au–Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

The formation of (Ni-Co-Sb)-Ag-As ore shoots in hydrothermal galena-sphalerite-fluorite veins

Supergene oxidation of epithermal gold-silver mineralization in the Deseado massif, Patagonia, Argentina: response to subduction of the Chile Ridge

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