Volcanic stratigraphy, structural controls, and mineralization in the san cristobal Ag–Zn–Pb deposit, southern bolivia

Phillipson, S.E.; Romberger, S. B.

doi:10.1016/j.jsames.2003.11.002

Cited by 11 publications

(5 citation statements)

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“…South of the orocline, Sn, Sn-W, and Sn-polymetallic mineralizations are "shallower" and related to porphyritic intrusions, dome complexes, hydrothermal breccia pipes, and collapse calderas. These eventually developed advanced argillic lithocaps within the epithermal environment over high-grade mesothermal (or xenothermal [60]) vein deposits [61,63,[66][67][68].…”

Section: Geodynamic Settingmentioning

confidence: 99%

Indium Mineralization in the Volcanic Dome-Hosted Ánimas–Chocaya–Siete Suyos Polymetallic Deposit, Potosí, Bolivia

et al. 2019

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A volcanic dome complex of Miocene age hosts the In-bearing Ánimas–Chocaya–Siete Suyos district in SW Bolivia. Ore mineralization occurs as banded and massive infillings in sub-vertical, NE-SW striking veins. In this article, a detailed petrographic study is combined with in situ mineral geochemistry determinations in ore from the Arturo, Chorro and Diez veins in the Siete Suyos mine, the Ánimas, Burton, Colorada, and Rosario veins in the Ánimas mine and the Nueva vein in the Chocaya mine. A three-stage paragenetic sequence is roughly determined for all of them, and includes (1) an early low-sulfidation stage that is dominated by cassiterite, pyrrhotite, arsenopyrite, and high-Fe sphalerite (FeS > 21 mol. %); (2) a second intermediate-sulfidation stage dominated by pyrite + marcasite ± intermediate product, sphalerite (FeS < 21 mol. %), stannite, and local famatinite; and, (3) a late intermediate-sulfidation stage dominated by galena and Ag-Pb-Sn sulfosalts. Electron-probe microanalyses reveal high indium enrichment in stage-2 sphalerite (up to 9.66 wt.% In) and stannite (up to 4.11 wt.% In), and a moderate enrichment in rare wurtzite (up to 1.61 wt.% In), stage-1 sphalerite (0.35 wt.% In), cassiterite (up to 0.25 wt.% In2O3), and ramdohrite (up to 0.24 wt.% In). Therefore, the main indium mineralization in the district can be associated to the second, intermediate-sulfidation stage, chiefly in those veins in which sphalerite and stannite are more abundant. Atomic concentrations of In and Cu in sphalerite yield a positive correlation at Cu/In = 1 that agrees with a (Cu+ + In3+) 2Zn2+ coupled substitution. The availability of Cu in the mineralizing fluids during the crystallization of sphalerite is, in consequence, essential for the incorporation of indium in its crystal lattice and would control the distribution of indium enrichment at different scales. The highest concentrations of indium in sphalerite, which is found in the Diez vein in the Siete Suyos mine, occur in crustiform bands of sphalerite with local “chalcopyrite disease” texture, which has not been observed in the other studied veins. In stannite, the atomic concentrations of In are negatively correlated with those of Cu and Sn at Cu + In = 2 and Sn + In = 1. Thus, atomic proportions and correlations suggest the contextualization of the main indium mineralization in the sphalerite–stannite–roquesite pseudoternary system.

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Section: Geodynamic Settingmentioning

confidence: 99%

Indium Mineralization in the Volcanic Dome-Hosted Ánimas–Chocaya–Siete Suyos Polymetallic Deposit, Potosí, Bolivia

et al. 2019

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“…Intermediate sulfidation Ag-Pb-Zn epithermal systems are a major source of Ag and also contain economic amounts of Au, Zn, Pb, and Cu (Simmons et al, 2005). Many of the wellknown examples of this particular ore deposit type are located in the Sierra Madre Occidental of Mexico, e.g., Fresnillo, Tayoltita, and Pachuca-Real del Monte (Simmons, 1991;Albinson et al, 2001;Camprubí and Albinson, 2007), with similar epithermal deposits occurring in Peru (Petersen et al, 1977;Candiotti de los Rios et al, 1990;Baumgartner et al, 2008;Rottier et al, 2018) and Bolivia (Phillipson and Romberger, 2004;Arce Burgoa, 2009), as well as in Spain (Concha et al, 1992), Australia (Oliver et al, 2019), and elsewhere (Sillitoe and Hedenquist, 2003). Many of these deposits have a distinct vertical and lateral zoning, which includes high-grade Ag zones at shallow to intermediate depth (100-1,000 m) that systematically grade into more base metal-rich sulfide veins with increasing depth (Albinson et al, 2001;Simmons et al, 2005;Camprubí and Albinson, 2007;Oliver et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Spatial and Temporal Evolution of the Freiberg Epithermal Ag-Pb-Zn District, Germany

et al. 2021

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The Freiberg district hosts one of the largest series of epithermal polymetallic vein deposits in Europe. The availability of a systematic collection of historical samples provides an excellent opportunity to study the anatomy of these epithermal systems. Detailed petrographic investigations, geochemical analyses, and fluid inclusion studies were conducted on several vertical profiles within the Freiberg district to decipher mineralogical and geochemical zoning patterns. Six distinctive mineral associations have been recognized within the Freiberg epithermal veins; sphalerite-pyrite-quartz and galena-quartz±carbonate associations are most abundant in the central sector, as well as in the deepest sections of veins on the periphery of the district. A high-grade sphalerite-Ag-sulfides-carbonate association occurs laterally between the central and peripheral sectors and at intermediate depth in veins on the periphery. Shallow and peripheral zones are dominated by an exceptionally Ag-rich Ag-sulfides-quartz association, whereas the shallowest veins locally comprise Ag-poor stibnite-quartz and quartz-carbonate associations. Fluid inclusion assemblages returned low salinities (<6.0 wt % NaCl equiv), and homogenization temperatures successively decrease from ~320°C associated with the proximal and deep sphalerite-pyrite-quartz association, to ~170°C related to the distal and shallow Ag-sulfides-quartz association. The architecture of the Freiberg district is related to the temporal and spatial evolution of magmatic-hydrothermal fluid systems, including boiling and concomitant cooling, as well as CO2 loss. Constraints on the paleodepth indicate that the veins formed between 200 and 1,800 m below the paleowater table. High-grade Ag ore occurs over a vertical interval of at least 500 m and is bracketed by shallower stibnite-quartz and barren quartz, and deeper base metal-sulfide-quartz zones.

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“…4 type of ore deposits in the Tarapacá region contrasts with the large number of examples known in the Peruvian and Bolivian Andes such as Caylloma and Pallancata in Peru (Echavarría et al, 2006;GamarraUrrunaga et al, 2013) and San Cristóbal in Bolivia (Phillipson and Romberger, 2004).…”

Section: Accepted M Manuscriptmentioning

confidence: 91%

“…Cooling has also been described in some deposit as the main deposition process (e.g. San Cristobal deposit, Phillipson and Romberger, 2004) Sulfur and oxygen activities of the fluids during stage 2 have been estimated from the composition of sphalerite in equilibrium with pyrite according to Barton et al (1977). The composition of Sp 2A and Sp 2B in equilibrium with pyrite ranges from 6 to 15 mol.% FeS and plots within the sulfide dominant field in the sulfur vs. oxygen activity diagram (Fig.…”

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confidence: 99%

“…In other epithermal deposits, Ag-bearing minerals commonly precipitate during the last stages (e.g. Baumgartner et al, 2008;Bendezu and Fonboté, 2009;Gropper et al, 1991;Phillipson and Romberger, 2004;Vassileva et al, 2014) usually due to a combination of different factors involving mixing between magmatic and meteoric fluids, increasing oxygen fugacity and decreasing fluid temperature (Vassileva et al, 2014).…”

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confidence: 99%

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The Patricia Zn–Pb–Ag epithermal ore deposit: An uncommon type of mineralization in northeastern Chile

Chinchilla

Menor

Piña

et al. 2016

Ore Geology Reviews

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The Patricia ore deposit represents an unusual example of economic Zn-Pb-Ag mineralization at the northernmost end of the Late Eocene-Oligocene metallogenic belt in Chile. It is hosted by volcanosedimentary units, which are typically tuffaceous and andesitic breccias. The ore body consists of a set of subvertical E-W vein systems developed under a sinistral strike-slip regime that included transtensive domains with generalized extensional structures where the ores were deposited. The deposit is divided into two blocks by a set of NNW-ESE-trending reverse faults, which uplifted the eastern block and exhumed thicker and deeper parts of the deposit. At least 200 m of volcano-sedimentary pile hosting the mineralization has been eroded in this block. By contrast, the western block exposes a shallower part of the system where cherts, amorphous silica and jasperoids occur. Three main stages of mineralization have been defined: (1) pre-ore stage is characterized by early quartz, pyrite and arsenopyrite, (2) base-metal and silver stage; characterized by sphalerite (6 to 15 mol.% FeS), galena, chalcopyrite, pyrrhotite and Agbearing minerals (freibergite, polybasite, stephanite, pyrargyrite, freieslebenite and acanthite) and (3) post-ore stage; characterized by late quartz, kutnohorite and minor sulfides (arsenopyrite, sphalerite,pyrite, galena, Ag-bearing minerals and Pb-sulfosalts). Whole-ore geochemistry shows two groups of elements that are positively correlated; 1) Ag-Cd-Cu-Pb-Zn related to the base metal sulfides and 2) AuAs-Ge-Sb-W related to arsenopyrite and pyrite. Hydrothermal alteration is pervasive in the outcropping mineralized areas, including silicification and locally, vuggy silica textures. At depth, chloritic and sericitic alteration is developed along vein selvages and is superimposed to the regional propylitic alteration. Fluid inclusions indicate that the base-metal ores were deposited from 250-150º C moderate salinity fluids (1-9 wt % NaCl). The pre-ore stage is characterized by a saline fluid (6-22 wt % NaCl) and between 210 and 250ºC whereas the post-ore stage has salinity of 4-8 wt % and temperature from 175 to 215ºC. Cooling was the mechanism of ore mineral precipitation in the Patricia deposit, although mixing of fluids could have occurred in the pre-ore stage. Mineralogical, geochemical and fluid inclusion evidence is consistent with an intermediate sulfidation (IS) epithermal deposit type. This study highlights the high potential for hidden economic mineralization at depth in the western block and for extension of the ore body both to the south and to deeper levels in the eastern block of the Patricia ore deposit. To a larger extent, the implications of finding such polymetallic epithermal style of mineralization in the northern Chile Precordillera is relevant both to the regional metallogenic perspective and to the exploration potential of the region, where the late Eocene-early Oligocene metallogenic belt apparently disappears.

show abstract

Volcanic stratigraphy, structural controls, and mineralization in the san cristobal Ag–Zn–Pb deposit, southern bolivia

Cited by 11 publications

References 5 publications

Indium Mineralization in the Volcanic Dome-Hosted Ánimas–Chocaya–Siete Suyos Polymetallic Deposit, Potosí, Bolivia

Indium Mineralization in the Volcanic Dome-Hosted Ánimas–Chocaya–Siete Suyos Polymetallic Deposit, Potosí, Bolivia

Spatial and Temporal Evolution of the Freiberg Epithermal Ag-Pb-Zn District, Germany

The Patricia Zn–Pb–Ag epithermal ore deposit: An uncommon type of mineralization in northeastern Chile

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