Thermodynamic predictions of the hydrothermal chemistry of arsenic, and their significance for the paragenetic sequence of some cassiterite-arsenopyrite-base metal sulfide deposits

Heinrich, Christoph A.; Eadington, Peter J.

doi:10.2113/gsecongeo.81.3.511

Cited by 183 publications

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“…All these facts show that redox reactions between reduced form of carbon and tin on one hand and oxidized form of arsenic and sulfur on the other occur in the solutions. Reactions between compounds of tin and arsenic are the most important for the precipitation of arsenopyrite (Heinrich and Eadington, 1986). Sulfate sulfur seems to participate in this reaction along with arsenic.…”

Section: Redox Reactions In the Solutions And The Sources Of The Ore-mentioning

confidence: 99%

Isotopic and geochemical study of the conditions of tin ore formation of Solnechnoye deposit(Far East of Russia).

et al. 1994

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Physical chemical characteristics of the Solnechnoye tin deposit hydrothermal system have been stud ied. Ores of cassiterite-tourmaline type was formed in a vertically dipping fracture zone, extended up to 8 km in a metamorphosed mass of sandstone-shale rocks. This rock mass transfers in its root part to a granitoid massif (quartz diorites-monzonites).The evolution in composition of the mineral-forming solution was studied by gas-chromatographic analysis of gaseous phase of fluid inclusions. The analysis of aqueous extracts from fluid inclusions (AAS, potentiometry, ICP and ionic chromatography) was also performed. It was found that as the process proceeded from the preore quartz-tourmaline stage to productive quartz-cassiterite, the values of axco-' a(s11), C02/CH4, HCO3/Cl and pH increased. The value of foe corresponded to the F-Q-M buffer on thie preore stage and increased up to that of the Ni-NiO buffer during the formation of the main part of cassiterite ores.Study of organic compounds showed that a greater degree of oxidation in comparison to the preore stage is typical for the quartz-cassiterite and the main sulfide stages. It means that organic compounds participated in redox reactions which took place in the solutions during the precipitation of these mineral assemblages.The 8180 values of fluids calculated from the 8180 values obtained for the minerals show a distinct trend of decrease toward later stages. The 8D values for the waters from the inclusions are close to those found for contemporary meteoric waters (-120%o). A transport model of non-isothermal isotope exchange between water and arbitrary number of minerals along the fluid flow paths was used for the interpretation of these isotope data as well as of the data on the isotope composition of the wall-rocks. Descending flow of meteoric waters was found to interact with sandstone-shale rocks and with granitoids before entering into the discharge zone. Thus while studying reasons of ore formation in a given hydrothermal system it is necessary to answer subsequently several questions: a) what are the main changes in the physical chemical prop erties of fluid in the process of the ore formation; b) which of the factors plays the decisive role in the deposition of ore material; c) with which re actions these changes are coupled; and d) which properties of the hydrothermal system are respon sible for the changes of physical chemical condi tions in the solutions. Large economic tin deposit Solnechnoye was chosen for the main object of our study. This de posit is a typical representative of tourmaline type of cassiterite-silicate formation according to the classification (Lugov et al., 1976). Some ques tions of geological structure, chemical and miner alogical compositions of this deposit have been discussed by several authors (Gonevchuk et al., 1984). Many papers (Bannikova et al., 1984(Bannikova et al., , 1989Kokorina, 1982;Sushchevskaya et al., 1978Sushchevskaya et al., , 1984 are dedicated to the problems of physical chemi cal conditions of its for...

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Section: Redox Reactions In the Solutions And The Sources Of The Ore-mentioning

confidence: 99%

Isotopic and geochemical study of the conditions of tin ore formation of Solnechnoye deposit(Far East of Russia).

et al. 1994

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“…In the following pages, I try to apply this model of separation of two solutions by boiling to the Huanzala and other deposits. For this speculation, I referred some papers by Krauskopf (1957Krauskopf ( , 1964Krauskopf ( , 1965, Heinrich and Eadington (1986), and Spycher and Reed (1989). Table 1 shows the paragenesis observed in the Huanzala deposits, as revised from the previous paper (Imai et al, 1985).…”

Section: Some Problems On the Mineralization Of The Huanzala Depositsmentioning

confidence: 98%

Mineralizations of Base Metal Deposits of Acid‐Sulfate Type Coexisting with Adularia‐Sericite Type

Imai¹

1999

Resource Geology

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: Two types of ores are recognized in the Huanzala mine, Peru. Zinc and lead ore of adularia‐sericite type, is accompanied by pyrite body and skarn. Orthoclase (adularia), sericite and calcite are found in the skarn and altered country rocks. On the other hand, copper and silver (tin) ore of acid‐sulfate type, is characterized by enargite, luzonite and bornite, accompanied by tin, silver and tellurium minerals. Although sericite and calcite are found only at the earlier stage in the mineralization of acid‐sulfate type, kaolinite appears in the country rocks at a subsequent stage. It is interpreted that the ore‐forming fluid of the acid‐sulfate type separated from the adularia‐sericite type by boiling in the early stage of mineralization. The separated fluid was nearly neutral just after boiling and changed into acidic by the oxidation of H2S into HSO4‐. Both types of mineralizations are studied in terms of fo2‐fs2‐pH‐temperature diagrams. The adularia‐sericite type might correspond to the hot‐water system of a geothermal area, and the acid‐sulfate type to the vapor‐dominated system. The copper ores from the Teine mine, Hokkaido, Japan and the Chinkuashih mine, Taiwan are acid‐sulfate type, characterized by the occurrence of enargite and luzonite. However, zinc and lead ores of the adularia‐sericite type are also present in these deposits. Both types in the Teine and Chinkuashih deposits are supposed to have formed in the similar relation as in the Huanzala deposits. The enargite and luzonite ores in the Hokuetsu mine, Japan are closely associated with native sulfur of solfataric origin.

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“…Arsenopyrite is common in tin-rich greisens related to granitic plutons that crosscut black shales, such as La Parrilla (Mangas, 1987) or Panasqueira (Polya, 1989). Also, Heinrich and Eadington (1986) have shown that arsenic and tin can be transported easily together in acid and reduced fluids. Thus, Sn-As rich greisens are probably formed at more reducing conditions than those estimated here.…”

Section: The Navalcubilla Granite and Related Hydrothermal Alterationsmentioning

confidence: 99%

“…Eugster, 1985;Heinrich, 1990). There have been recent contributions to the understanding on the behaviour of tin, tungsten and arsenic in early, hightemperature, hydrothermal processes (Heinrich and Eadington, 1986;Heinrich, 1990). The general conclusions of these studies can be applied to the high-temperature greisens (types [a] and [b]), but cannot be used to evaluate the low-temperature processes and predict the formation of the chloriterich greisens, where fluids are cooler and geochemically different.…”

Section: Introductionmentioning

confidence: 99%

A numerical approach for the formation of chlorite and sulphide-bearing greisen: a study based on the Navalcubilla system (Spanish Central System)

Tornos¹

1997

Mineral. mag.

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The formation of sulphide and cassiterite-bearing chlorite-rich greisens in the Navalcubilla granite has been modelled theoretically. Numerical simulation on the reaction of a hydrothermal fluid with a granitic rock predicts assemblages very similar to those found in nature, with progressive formation of muscovite, quartz, chlorite, microcline and plagioclase zones. The hydrothermal alteration of the rock produces a neutralization of the inflowing acid fluid, a drop in thefs2 and, to a lesser degree, an increment in fo2. During hydrothermal alteration, fs2 and fo2 change abruptly between metasomatic zones, but chlorite seems to control their major changes. Scheelite and cassiterite are concentrated in the internal zones, while sulphides are related to the more external zones. Fluid-rock reactions seem to be very effective for precipitating cassiterite and scheelite, even from very Sn and W-poor fluids. Appreciable amounts of sulphides are only expected in systems with high concentrations of base metals. Boiling and simple cooling of the fluids acidifies and oxidizes them but chemical changes are not strong enough to induce significant precipitation of ore minerals, at least when the temperature changes are small. Continued circulation of fluids along fractures with previously precipitated quartz + wolframite produces replacement of wolframite by scheelite and sulphides.

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Thermodynamic predictions of the hydrothermal chemistry of arsenic, and their significance for the paragenetic sequence of some cassiterite-arsenopyrite-base metal sulfide deposits

Cited by 183 publications

References 0 publications

Isotopic and geochemical study of the conditions of tin ore formation of Solnechnoye deposit(Far East of Russia).

Isotopic and geochemical study of the conditions of tin ore formation of Solnechnoye deposit(Far East of Russia).

Mineralizations of Base Metal Deposits of Acid‐Sulfate Type Coexisting with Adularia‐Sericite Type

A numerical approach for the formation of chlorite and sulphide-bearing greisen: a study based on the Navalcubilla system (Spanish Central System)

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