Progressive 18O depletion during CO2 separation from a carbon dioxide-rich hydrothermal fluid: evidence from the Grey River tungsten deposit, Newfoundland

1982 ◽  
Vol 19 (12) ◽  
pp. 2247-2257 ◽  
Author(s):  
N. C. Higgins ◽  
R. Kerrich
Keyword(s):  
Hydrothermal Fluid ◽  
Chemical Change ◽  
Co2 Separation ◽  
Tungsten Deposit ◽  
Magmatic Origin ◽  
Low Salinity ◽  
Oxygen Isotopic ◽  
Retrograde Boiling ◽  
Fractionation Factors ◽  
Tungsten Deposits

Oxygen isotope data for the Grey River tungsten prospect, Newfoundland, Canada, indicate a progressive depletion in δ18Ofluid during mineralization. Early veins with pegmatitic affinities were deposited at 470 °C and pressures greater than 1 kbar (100 MPa), from a fluid with a δ18O composition of 7.4‰, presumed to be of magmatic origin. Successive vein deposition, at progressively lower temperatures and pressures, culminated in the precipitation of wolframite-bearing veins at a temperature of 300 °C and pressures of 150–320 bar (15–32 MPa), from a low salinity fluid with a δ18O composition in the range 3.2–1.6‰.Low values of δ18O (and δDfluid) are recorded in many vein tungsten deposits and are normally interpreted as reflecting mixing of isotopically light meteoric fluids or formation brines with magmatic fluids. However, fluid-inclusion evidence for the Grey River mineralization indicates that a 40 mol% CO2 loss occurred by immiscibility and retrograde boiling of the hydrothermal fluid between 420 and 300 °C. Such a chemical change would have significantly altered the oxygen isotopic character of the hydrothermal fluid since CO2 fractionates 18O relative to coexisting water by ~10‰ at 400 °C and ~14‰ at 300 °C. Calculations using available CO2–H2O fractionation factors reveal that up to a 7‰ depletion in δ18O of the residual aqueous fluids may occur as a result of the 40 mol% CO2 loss from the hydrothermal fluid.

scholarly journals Fluid Inclusion and Oxygen Isotope Constraints on the Origin and Hydrothermal Evolution of the Haisugou Porphyry Mo Deposit in the Northern Xilamulun District, NE China

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Qihai Shu ◽  
Yong Lai
Keyword(s):  
Fluid Inclusion ◽  
Meteoric Water ◽  
Early Time ◽  
Low Oxygen ◽  
Potassic Alteration ◽  
Low Salinity ◽  
Oxygen Isotopic ◽  
Homogenization Temperatures ◽  
Porphyry Mo Deposit ◽  
Positive Correlations

The Haisugou porphyry Mo deposit is located in the northern Xilamulun district, northeastern China. Based on alteration and mineralization styles and crosscutting relationships, the hydrothermal evolution in Haisugou can be divided into three stages: an early potassic alteration stage with no significant metal deposition, a synmineralization sericite-chlorite alteration stage with extensive Mo precipitation, and a postmineralization stage characterized by barren quartz and minor calcite and fluorite. The coexistence of high-salinity brine inclusions with low-salinity inclusions both in potassic alteration stage (~440°C) and locally in the early time of mineralization stage (380–320°C) indicates the occurrence of fluid boiling. The positive correlations between the homogenization temperatures and the salinities of the fluids and the low oxygen isotopic compositions (δ18Ofluid < 3‰) of the syn- to postmineralization quartz together suggest the mixing of magmatic fluids with meteoric water, which dominated the whole mineralization process. The early boiling fluids were not responsible for ore precipitation, whereas the mixing with meteoric water, which resulted in temperature decrease and dilution that significantly reduced the metal solubility, should have played the major role in Mo mineralization. Combined fluid inclusion microthermometry and chlorite geothermometer results reveal that ore deposition mainly occurred between 350 and 290°C in Haisugou.

scholarly journals Mineral composition and formation conditions of the Inkur tungsten deposit ores (Dzhidinsky ore field, South-Western Transbaikalia)

2020 ◽  
Vol 43 (3) ◽  
pp. 290-306
Author(s):  
L. B. Damdinova ◽  
B. B. Damdinov
Keyword(s):  
Mineral Composition ◽  
Tungsten Deposit ◽  
Homogeneous Solutions ◽  
Western Transbaikalia ◽  
Low Salinity ◽  
Mineral Associations ◽  
Formation Conditions ◽  
The Individual ◽  
Two Stages ◽  
Petrographic Description

The aim of the study is to clarify the mineral composition and determine the conditions of the formation of the quartz-hubnerite veins of the Inkur stockwork tungsten deposit (the Dzhidinsky ore field, South-Western Transbaikalia). The research methods include a mineralogical and petrographic description of the ore quartz-hubnerite veins; an electron microprobe analysis of the mineral associations; thermometry, cryometry, and Raman spectroscopy of the individual fluid inclusions in quartz, fluorite, hubnerite, and muscovite. The mineralogical and petrographic studies has made it possible to clarify the mineral composition of the Inkur deposit ores and determine the mineral paragenesis formation sequence. The fluid inclusion studies have established that the ore deposition was occurring in the relatively low-salinity (~5.7–14.6 wt. % eq. NaCl) homogeneous solutions due to a decrease of the temperature. The study of the salt composition of the solutions has identified Ca chloride as a prevailing component, with NaCl, KCl, and MgCl as admixtures. CO2 and N2 have been identified in the gas phase of inclusions. Two stages of mineral formation have been defined: high-temperature (≥300 °С) and low-temperature (≥2.00–300 °С). The conducted studies allow qualitative estimation of the chemical composition of the ore-forming solutions. It has been established that one of the main factors of the hubnerite deposition is a temperature factor.

scholarly journals Geology and characteristics of Pb-Zn-Cu-Ag skarn deposit at Ruwai, Lamandau Regency, Central Kalimantan

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Arifudin Idrus ◽  
Lucas Donny Setijadji ◽  
Fenny Tamba ◽  
Ferian Anggara
Keyword(s):  
Low Temperature ◽  
Hydrothermal Fluid ◽  
Meteoric Water ◽  
Volcanic Rocks ◽  
Thrust Fault ◽  
Strike Slip ◽  
Skarn Deposit ◽  
Central Kalimantan ◽  
Low Salinity ◽  
Ore Mineralization

This study is dealing with geology and characteristics of mineralogy, geochemistry and physicochemical conditions of hydrothermal fluid responsible for the formation of skarn Pb-Zn-Cu-Ag deposit at Ruwai, Lamandau Regency, Central Kalimantan. The formation of Ruwai skarn is genetically associated with calcareous rocks consisting of limestone and siltstone (derived from marl?) and controlled by NNE-SSW-trending strike slip faults and localized along N 70° E-trending thrust fault, which also acts as contact zone between sedimentary and volcanic rocks in the area. Ruwai skarn is mineralogically characterized by prograde alteration (garnet and clino-pyroxene) and retrograde alteration (epidote, chlorite, calcite and sericite). Ore mineralization is characterized by sphalerite, galena, chalcopyrite and Ag-sulphides (particularly acanthite and argentite), which formed at early retrograde stage. Geochemically, SiO2 is enriched and CaO is depleted in limestone, consistent with silicic alteration (quartz and calc-silicate) and decarbonatization of the wallrock. The measured reserves of the deposit are 2,297,185 tonnes at average grades of 14.98 % Zn, 6.44 % Pb, 2.49 % Cu and 370.87 g/t Ag. Ruwai skarn orebody originated at moderate temperature of 250-266 °C and low salinity of 0.3-0.5 wt.% NaCl eq. The late retrograde stage formed at low temperature of 190-220 °C and low salinity of ~0.35 wt.% NaCl eq., which was influenced by meteoric water incursion at the late stage of the Ruwai Pb-Zn-Cu-Ag skarn formation. Keywords: Geology, skarn, mineralogy, geochemistry, Ruwai, Central Kalimantan

Ore-Forming Fluid System of the Anqing Cu-Fe Deposit, Anhui Province, China

2013 ◽  
Vol 734-737 ◽  
pp. 135-138
Author(s):  
Guang Shu Yang ◽  
Yong Feng Yan ◽  
Peng Yu Feng
Keyword(s):  
High Temperature ◽  
Fluid Inclusions ◽  
Hydrothermal Fluid ◽  
Anhui Province ◽  
Forming Process ◽  
Fluid System ◽  
Physicochemical Condition ◽  
Magmatic Water ◽  
Ore Minerals ◽  
Oxygen Isotopic

Fluid inclusions, carbon and oxygen isotopic compositions were discussed to understanding the ore-forming fluid system of Anqing Cu-Fe deposit. Homogeneous temperatures of fluid inclusions ranged from 124°C to 570°C, δ13CPDBvalues of the gangue minerals ranged from-3.3 to-0.9, and δ18O values ranged from 9.4 to 10.7, respectively. The results reveal that the primary ore-forming fluid was magmatic hydrothermal fluid characterized by high temperature, the boiling and mixing of fluids occurred in the main mineralization stage, the magmatic water was dominant in the ore-forming process, the physicochemical condition changes of the fluid system led to the formation of skarn and the deposition of the ore minerals. The ore-forming materials were mainly derived from magma, partly provided by sedimentary strata.

scholarly journals Characteristics and formation mechanisms of silicified carbonate reservoirs in well SN4 of the Tarim Basin

2018 ◽  
Vol 36 (4) ◽  
pp. 820-849 ◽  
Author(s):  
Donghua You ◽  
Jun Han ◽  
Wenxuan Hu ◽  
Yixiong Qian ◽  
Qianglu Chen ◽  
...  
Keyword(s):  
Tarim Basin ◽  
Hydrothermal Fluid ◽  
High Salinity ◽  
Carbonate Reservoirs ◽  
High Yield ◽  
Formation Mechanisms ◽  
Lower Section ◽  
Yingshan Formation ◽  
Low Salinity ◽  
Homogenization Temperatures

High-yield natural gas was discovered in well SN4 in the Ordovician Yingshan Formation in the Tarim Basin. The gas is found in unusual, silicified, carbonate reservoirs. According to the degree of silicification, the silicified reservoirs can be divided into a lower section of silicified carbonates, a middle section of limestone, and an upper section of silicified carbonates. The silicified carbonates are mainly composed of quartz and calcite, in which the reservoir space mostly occurs as vugs, inter-crystalline pores of quartz, and partial fractures. Porosity varies widely, ranging from 3 to 20.5% with strong heterogeneity. The homogenization temperatures of fluid inclusions in quartz and calcite show that the silicification temperatures were 150–190°C, with characteristics of high temperature/low salinity and low temperature/high salinity. The 87Sr/86Sr ratios of secondary calcite are 0.709336–0.709732, which are significantly higher than that of concurrent seawater, indicating that the hydrothermal fluid originated from the deep clastic strata or the basement (sialic rock). The δ13C values of the secondary calcite are similar to that of the surrounding limestone, indicating that the carbon in the secondary calcite is derived from the limestone strata, and that the secondary calcite is the product of dissolution and re-precipitation resulting from interaction between the silica-bearing hydrothermal fluids and surrounding limestones. The silicification of silica-bearing hydrothermal fluid was significantly controlled by strike-slip faults. The fluids ascending along the fault zone and branch faults interacted with the surrounding limestone in the Yingshan Formation. As a result, a large amount of quartz and secondary calcite were formed together with various types of secondary pores, resulting in excellent reservoirs.

Fluid inclusion evidence for the transport of tungsten by carbonate complexes in hydrothermal solutions

1980 ◽  
Vol 17 (7) ◽  
pp. 823-830 ◽  
Author(s):  
N. C. Higgins
Keyword(s):  
Carbon Dioxide ◽  
Fluid Inclusion ◽  
Hydrothermal Fluid ◽  
Fluid Pressure ◽  
Hydrothermal Fluids ◽  
Hydrothermal Solutions ◽  
High Fluid ◽  
Carbonate Complexes ◽  
Very High ◽  
Tungsten Deposits

Fluid inclusion evidence from the Grey River Tungsten Prospect, Newfoundland, and other tungsten deposits indicates that CO2 is an important component of the hydrothermal fluid. Carbon dioxide is enriched in fluids evolved from granitic melts under high fluid pressure, while lower pressure fluids are chloride-rich. The association of tungsten deposits with these carbon dioxide rich hydrothermal fluids suggests that carbonate/bicarbonate complexes may be important in tungsten transport at very high fluid pressures.

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