Sulfur isotopic method for discriminating between sulfates of hypogene and supergene origin

Field, Cyrus W.

doi:10.2113/gsecongeo.61.8.1428

Cited by 71 publications

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“…The use of stable isotope data on alunite as a tool to distinguish different environments in fossil epithermal systems has been demonstrated in various studies (Field, 1966;Jensen et al, 1971;Bethke, 1984;Rye et al, 1988). The relation between the stable isotope ratios of alunite and the environment of formation of acid-sulfate alteration was recognized by Bethke et al, (1984) and the genetic process has been documented recently by Rye et al, (1988Rye et al, ( , 1989 in a comprehensive study of 16 epithermal systems worldwide (including the data presented here on Rodalquilar).…”

Section: Stable Isotope Geochemistrymentioning

confidence: 80%

Preliminary study of the ore deposits and hydrothermal alteration in the Rodalquilar caldera complex, southeastern Spain

Arribas¹,

Rytuba²,

Rye³

et al. 1989

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SUMMARYThe Rodalquilar gold-alunite deposits are the first documented example of calderarelated epithermal gold mineralization in Europe. Mineralization occurs in rhyolitic tuffs and domes of the Rodalquilar caldera complex in the Miocene Cabo de Gata volcanic field. Geologic constraints indicate a close temporal relationship between the mineralization and a late magmatic phase of the caldera cycle. A zone of extensive advanced argillically altered rocks trends from east to west through the caldera and is well delineated by Landsat Thematic Mapper data. Aeromagnetic and gravity data show that an east-west trending gravity and aeromagnetic high coincides with the distribution of the altered rock. The source of this geophysical anomaly is considered to be andesitic magma that intruded into the base of the volcanic pile and is regarded as the heat source responsible for hydrothermal circulation, niite and alunite K-Ar data indicate an age for the mineralization of 10.8 Ma. Recent drilling in the core of the system shows that hydrothermally altered rocks continue to depths of over 900 m and are characterized by assemblages typical of acid-sulfate epithermal systems. A deep sericitic zone, with chlorite present below about 500 m, grades upward into argillic, advanced argillic and silicic (vuggy silica) zones. Zonation of the alteration assemblages also occurs laterally; the advanced argillic alteration mineral assemblage is replaced by chlorite within the argillic zone at or near the ground surface.Ore deposits within the Rodalquilar complex consist of alunite, gold-alunite, and lead-zinc-silver-gold veins. The gold-alunite deposits are the most important economically. They are preferentially localized in ring and radial fractures of the Lomilla caldera nested within the Rodalquilar caldera. Gold extends over a vertical interval of about 200 m below the original paleosurface and changes at depth to a complex sulfide assemblage. Most gold was deposited in the highest part of the center of upwelling fluid following the peak of acidic alteration. Highest gold values, with a median near 8 g/t, occur in black, pyritic, banded chalcedony that fills preexisting open spaces and fractures within advanced argillically altered rocks. Hypogene alunite in the central core assemblage reaches depths of more than 300 m, is characterized by high sodium content, and is accompanied, below the zone of supergene oxidation, by kaolinite, zunyite, diaspore, pyrite and aluminum phosphate-sulfates. Stable isotope data indicate that this alunite formed in a magmatichydrothermal environment from the disproportionate of SO2 derived from a magma. The 6^4S data of coeval pyrite indicate the 834S of bulk sulfur in the system was ~7 per mil. Barren alunite-jarosite veins are extensive throughout the district to a depth of about 50 m. Stable isotope data from these alunites indicate that they were derived by the oxidation of H2S in a steam-heated environment that in some places was superimposed on the advanced argillic assemblage as the hydrotherma...

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Section: Stable Isotope Geochemistrymentioning

confidence: 80%

Preliminary study of the ore deposits and hydrothermal alteration in the Rodalquilar caldera complex, southeastern Spain

Arribas¹,

Rytuba²,

Rye³

et al. 1989

Open-File Report

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“…Oxidation of sulfide minerals to sulfate at low temperatures is generally a quantitative and unidirectional process that causes negligible sulfur-isotope fractionation. This often results in d 34 S SO 4 values being indistinguishable from those of the parent sulfide minerals (Gavelin et al 1960;Nakai and Jensen 1964;Field 1966;Rye et al 1992;Balci et al 2007Balci et al , 2012. Because negligible and minor fractionation of S isotopes occurs during the oxidative weathering of sulfide minerals (Field 1966;Seal 2003;Balci et al 2007Balci et al , 2012, the d 34 S signature of dissolved SO 4 in the lakes should be similar to that of the sulfur source.…”

Section: Water Column and Sediments Of Amlmentioning

confidence: 99%

Generation of Acid Mine Lakes Associated with Abandoned Coal Mines in Northwest Turkey

Yücel

Balcı

Baba

2016

Arch Environ Contam Toxicol

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A total of five acid mine lakes (AMLs) located in northwest Turkey were investigated using combined isotope, molecular, and geochemical techniques to identify geochemical processes controlling and promoting acid formation. All of the investigated lakes showed typical characteristics of an AML with low pH (2.59-3.79) and high electrical conductivity values (1040-6430 lS/cm), in addition to high sulfate (594-5370 mg/l) and metal (aluminum [Al], iron [Fe], manganese [Mn], nickel [Ni], and zinc [Zn]) concentrations. Geochemical and isotope results showed that the acid-generation mechanism and source of sulfate in the lakes can change and depends on the age of the lakes. In the relatively older lakes (AMLs 1 through 3), biogeochemical Fe cycles seem to be the dominant process controlling metal concentration and pH of the water unlike in the younger lakes (AMLs 4 and 5). Bacterial species determined in an older lake (AML 2) indicate that biological oxidation and reduction of Fe and S are the dominant processes in the lakes. Furthermore, O and S isotopes of sulfate indicate that sulfate in the older mine lakes may be a product of much more complex oxidation/dissolution reactions. However, the major source of sulfate in the younger mine lakes is in situ pyrite oxidation catalyzed by Fe(III) produced by way of oxidation of Fe(II). Consistent with this, insignificant fractionation between d 34 S SO 4 and d 34 S FeS 2 values indicated that the oxidation of pyrite, along with dissolution and precipitation reactions of Fe(III) minerals, is the main reason for acid formation in the region. Overall, the results showed that acid generation during early stage formation of an AML associated with pyrite-rich mine waste is primarily controlled by the oxidation of pyrite with Fe cycles becoming the dominant processes regulating pH and metal cycles in the later stages of mine lake development.Acidic and highly metal-loaded effluents (acid mine drainage [AMD]) resulting from the exposure of pyrite and other metal sulfide minerals to weathering conditions are the principal environmental problems faced by the mining industry today (Dold and Spangerberg 2005).The formation mechanisms of AMD (e.g., oxidation of pyrite and other sulfide minerals) has been extensively studied

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“…Various investigations indicated that the sulfur isotopic composition of cinnabar or stibnite in all of the mercury, antimony and gold deposits in the East Guizhou region, is homogeneous and rich in the heavy sulfur isotope 34 S, that is to say, the 8 34 S value in these deposits is always positive, ranging from 10 to 20 %o 8 34 S. These sulfur isotope values indicate that the sulfur has been derived from sedimentary rocks (e.g. : Brown, 1967, Field, 1966. ( ), Hua (1982 and Zhang(1983) These studies point out that the source of sulfur in the sulfide minerals in the Danzhai gold-mercury deposit is the host sedimentary rocks.…”

Section: Chapter Vi: Argon Isotope Investigation Of Quartz Associatedmentioning

confidence: 99%

Le lien genetique entre la mineralisation en or et en mercure et l evolution petrolifere

Lu¹

1994

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The Danzhai gold-mercury deposit is situated in the eastern region of Guizhou province, southwest of P. R. China.The Danzhai deposit is one of the gold-mercury-antimony-barite deposits in the Sandou-Danzhai ore belt, which is controlled by regional fault system Fi. The host rocks are Upper Cambrian and Lower Ordovician carbonates. Wall rock alteration is dominated by silicification and carbonatization. The major mineral assemblages consist of cinnabar, arsenopyrite, stibnite, pyrite and realgar, orpiment as well as barite. Chemical analyses show that gold is positively correlated with arsenic so that the gold may be mainly associated with arsenic minerals. The Au/Ag ratio is always greater than 1 in the gold ore. Hydrocarbons, particularly bitumen, are abundant in both the host rocks and the ore. The geological characteristics of the Danzhai gold-mercury deposit is quite similar to that of Carlin gold deposit in the western U.S.A except the Danzhai deposit is rich in organic matter and not associated with igneous rocks.A number of gold-mercury-antimony-barite deposits are distributed in or around the Majiang-Danzhai oil trap, and all of these deposits are present under the ancient interface between petroleum and oilfield brine (-500 m). Field observation shows that a variety of forms of hydrocarbon occur not only in the host carbonates but in the ore deposit as well. Patch-like bitumen, veinlet bitumen as well as stylolite-like bitumen host sulfide minerals such as arsenopyrite and cinnabar while metal sulfides such as cinnabar and gangue minerals also host bitumen. Besides bitumen, paraffin wax is also found in the deposit. An organic petrography study demonstrates that the bitumen in the minerals from the deposit is identical to the bitumen in the former Majiang-Danzhai oil trap. The bitumen is actually pyrobitumen, with a high reflectance, a mosaic texture, and an anisotropic nature but without fluorescence. The reflectance of bitumen from the deposit is high, varying from 2 to 3.8%, and the temperature calculated from this reflectance ranges from 150 to 210°C, indicating that the petroleum in the Majiang-Danzhai oil trap reached the thermal natural gas stage.

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Sulfur isotopic method for discriminating between sulfates of hypogene and supergene origin

Cited by 71 publications

References 0 publications

Preliminary study of the ore deposits and hydrothermal alteration in the Rodalquilar caldera complex, southeastern Spain

Preliminary study of the ore deposits and hydrothermal alteration in the Rodalquilar caldera complex, southeastern Spain

Generation of Acid Mine Lakes Associated with Abandoned Coal Mines in Northwest Turkey

Le lien genetique entre la mineralisation en or et en mercure et l evolution petrolifere

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