Chloride Fluid Research Articles

Research of the Uranium, Niobium, and Tantalum Behavior in the Granite Melt–Chloride Fluid System at 750°C and 1000 Bar

The major objective of the study investigation was to find the physicochemical conditions for U, Nb, and Ta mobilization into the solution from acidic melts similar in composition to rhyolitic inclusions in quartz at the unique Streltsovka Mo–U field (Eastern Transbaikalia). The experiments were performed with model homogeneous leucogranite glass (wt %): 72.18 SiO2, 12.19 Al2O3, 1.02 FeO, 0.2 MgO, 0.33 CaO, 4.78 Na2O, 3.82 K2O, 1.44 Li2O, and 2.4 F (LiF, NaF, KF, CaF2, and MgF2); synthetic uranium dioxide; and natural columbite in solutions containing from 1 to 8 mol kg–1 chlorides (Na, K, and Li) at 750°C, 1000 bar, with an O2 (H2) fugacity set by the Ni–NiO buffer. The selected T–P parameters and solutions corresponded to the homogeneous and fluid immiscibility regions in the NaCl–KCl–H2O solutions. The Nb and Ta contents in the Cl–F solutions in equilibrium with F-bearing melts are very low. The U content is much higher and reaches about 1 × 10–4 wt % in the low-density fluid phase and n × 10–3 wt % in the dense aqueous saline phase (brine). The U content in the glass was tenths of a percent. Despite the very high chlorine content in the studied solutions, its content did not exceed 0.5 wt % in the glass. In the course of the experiments, columbite dissolved incongruently in the glass melt to form F- and U-bearing pyrochlores. According to the investigation results, the predominantly chloride fluid with the studied T–P parameters should not be considered an active medium for mobilization of U from Li–F granite melts in the formation of unique hydrothermal U (Mo–U) deposits.

Hydrogeochemical model of Ciseeng geothermal field, Bogor, West Java

Ciseeng geothermal field is located Northwest of West Java 40 km from Jakarta. Three surface manifestations are in Tirta Sayaga, Panjang Mountain, and Peyek Mountain. This study aims to build a hydrogeochemical model based on water analysis. The secondary regional geological data are retrieved to complete geological information of Ciseeng. The research method is divided into several stages: introduction includes the literature study, data collection includes the measurement of temperature and pH in several surface manifestations, rock sampling and structural geology analysis in Ciseeng. The type of manifestation that can be found in Ciseeng is a warm pool with chloride fluid type. Extensive travertine deposits were found in all three locations. The fluid temperature of three surface manifestations is about 30-38 °C with pH 6. According to the measurement of Na-K-Ca geothermometer, the reservoir temperature in Ciseeng geothermal field is 180 °C. The three manifestations of Ciseeng geothermal field are classified as mature water based on a ternary plot diagram. The isotopic analysis shows shifting in O18 indicating hydrothermal process due to magmatic activities in the subsurface. It is predicted that Ciseeng geothermal field is part of Salak/Pangrango Mountain geothermal system. The presence of surface manifestation confirms that geological structure trending from North to South, play a significant role to circulate the heated fluid in the subsurface and subsequently to the surface. The result is a geothermal conceptual model of Ciseeng field that shows the fluid origin and movement in the subsurface.

Ore-Forming Fluids of the Aleksandrovskoe and Davenda Deposits (Eastern Transbaikalia)

A study of the composition of fluid inclusions in ore minerals of the Davenda Mo–porphyry deposit and the Aleksandrovskoe sulfide–quartz–gold ore deposit, as well as of fluid inclusions in minerals of igneous rocks, showed that ore-forming fluids inherit the salt and gas composition of magmatic fluids generated during crystallization of ore-bearing rocks of the Amudzhikan–Sretensky Igneous Complex, which formed simultaneously with the Au and Mo mineralization. The gold-bearing sulfide–quartz veins of the Aleksandrovskoe deposit formed with the participation of two types of hydrothermal fluids, differing in the composition of salts and the gas phase: homogeneous Ca–Na chloride fluids with CO2 and heterophasic Na–K–Fe-chloride fluids, which indicates two sources of ore-forming fluids during the formation of Au-mineralization. Na–K–Fe-chloride fluids in terms of salt and gas composition were similar to the ore-forming fluids of the Mo-mineralization of the Davenda deposit. Ore-forming Ca–Na-chloride with CO2 The fluids of the Aleksandrovskoe field are comparable in salt and gas composition with the magmatogenic fluids of quartz diorite porphyries and diorite porphyrites. Ore forming Na–K–Fe carbonate-chloride fluids of the Davenda and Aleksandrovskoe deposits show great similarity in composition to magmatic fluids of granite porphyry and emphasize the genetic identity of Mo mineralization in both deposits. The data obtained confirm the widespread opinion that a genetic relationship exists between gold mineralization and dikes of intermediate and mafic composition, and molybdenum–porphyry mineralization with granite–porphyry of the Amudzhikan–Sretensky Igneous Complex. The real agents of this genetic link are metalliferous magmatogenic fluids, the salt and gas composition of which inherit ore-forming fluids. The formation depth of productive ore mineral assemblages in veins of the Aleksandrovskoe and Davenda deposits is estimated at 7.9–7 and 8–6.3 km, respectively, which is not typical of porphyry deposits, the formation of which is characterized by shallower depths.

AIDS-associated Talaromyces marneffei central nervous system infection in patients of southwestern China

BackgroundThe clinical and laboratory characteristics of AIDS-associated Talaromyces marneffei infection, a rare but a fatal mycosis disease of the central nervous system, remain unclear.Case presentationHerein, we conducted a retrospective study of ten AIDS patients with cerebrospinal fluid culture-confirmed central nervous system infection caused by Talaromyces marneffei. All 10 patients were promptly treated with antifungal treatment for a prolonged duration and early antiviral therapy (ART). Among them, seven patients were farmers. Nine patients were discharged after full recovery, while one patient died during hospitalization, resulting in a mortality rate of 10%. All patients initially presented symptoms and signs of an increase in intracranial pressure, mainly manifesting as headache, dizziness, vomiting, fever, decreased muscle strength, diplopia or even altered consciousness with seizures in severe patients. Nine patients (90%) showed lateral ventricle dilatation or intracranial infectious lesions on brain CT. Cerebrospinal fluid findings included elevated intracranial pressure, increased leukocyte count, low glucose, low chloride and high cerebrospinal fluid protein. The median CD4+ T count of patients was 104 cells/μL (IQR, 36–224 cells/μL) at the onset of the disease. The CD4+ T cell counts of three patients who eventually died were significantly lower (W = 6.00, p = 0.020) than those of the patients who survived.ConclusionsThe common clinical symptoms of T. marneffei central nervous system infection are associated with high intracranial pressure and intracranial infectious lesions. Earlier recognition and diagnosis and a prolonged course of amphotericin B treatment followed by itraconazole combined with early ART might reduce the mortality rate.

Mineralogy and Fluid Regime of Formation of the REE-Late-Stage Hydrothermal Mineralization of Petyayan-Vara Carbonatites (Vuoriyarvi, Kola Region, NW Russia)

The Vuoriyarvi Devonian alkaline–ultramafic complex (northwest Russia) contains magnesiocarbonatites with rare earth mineralization localized in the Petyayan-Vara area. High concentrations of rare earth elements are found in two types of these rocks: (a) ancylite-dominant magnesiocarbonatites with ancylite–baryte–strontianite–calcite–quartz (±late Ca–Fe–Mg carbonates) ore assemblage, i.e., “ancylite ores”; (b) breccias of magnesiocarbonatites with a quartz–bastnäsite matrix (±late Ca–Fe–Mg carbonates), i.e., “bastnäsite ores.” We studied fluid inclusions in quartz and late-stage Ca–Fe–Mg carbonates from these ore assemblages. Fluid inclusion data show that ore-related mineralization was formed in several stages. We propose the following TX evolution scheme for ore-related processes: (1) the formation of ancylite ores began under the influence of highly concentrated (>50 wt.%) sulphate fluids (with thenardite and anhydrite predominant in the daughter phases of inclusions) at a temperature above300–350 °C; (2) the completion of the formation of ancylite ores and their auto-metasomatic alteration occurred under the influence of concentrated (40–45 wt.%) carbonate fluids (shortite and synchysite–Ce in fluid inclusions) at a temperature above 250–275 °C; (3) bastnäsite ores deposited from low-concentrated (20–30 wt.%) hydrocarbonate–chloride fluids (halite, nahcolite, and/or gaylussite in fluid inclusions) at a temperature of 190–250 °C or higher. Later hydrothermal mineralization was related to the low-concentration hydrocarbonate–chloride fluids (<15 wt.% NaCl-equ.) at 150–200 °C. The presented data show the specific features of the mineral and fluid evolution of ore-related late-stage hydrothermal rare earth element (REE) mineralization of the Vuoriyarvi alkaline–ultramafic complex.

Physicochemical Conditions of Ore Formation at the Kalguty Mo–W Deposit: Thermodynamic Modeling

Thermodynamic modeling was carried out for the formation of Mo–W ores at the Kalguty deposit (Gornyi Altai). The modeling was based on the physicochemical conditions of Mo–W ore formation estimated from fluid inclusion data. Quartz–wolframite veins of the deposit were formed under the influence of homogeneous reduced carbonate–chloride fluids, which showed elevated W and Sb concentrations. Pyrite–chalcopyrite–molybdenite mineralization was formed under the influence of heterogeneous oxidized sulfate–carbonate–chloride fluids enriched in Cu, Mo, W, Bi, and S. The economic combined greisen–vein Mo–W (Be) mineralization of the Kalguty deposit was formed by the superposition of molybdenite–chalcopyrite mineralization on the mineral assemblages of earlier quartz–wolframite veins. Ore forming processes were modeled for the scenarios of isobaric cooling and rock–solution interaction in the presence of oxidized and reduced model solutions corresponding to the natural ore-forming fluids of the Kalguty deposit. The results of thermodynamic modeling allowed us to conclude that rock interaction with oxidizing acid solution enriched in Cu, Mo, Bi, W, and S is the most plausible model for the formation of the greisen Mo–W ores. The interaction was accompanied by the inversion of the Eh–pH parameters of oxidizing ore-forming fluid and changes in its metal content, salt composition, and gas components. The chalcopyrite–molybdenite mineralization was formed during cooling of hot (>400°C) metalliferous oxidizing acid fluids before the inversion of their Eh–pH parameters. Wolframite ores could be deposited from the same portion of ore-forming fluid after the Eh–pH inversion and cooling. The combined Mo–W mineralization of the Kalguty deposit could result from at least two hydrothermal rhythms characterized by similar physicochemical parameters of ascending ore-forming fluids. The level of ore formation of each successive hydrothermal rhythm moved upward. This resulted in the telescoping of the high-temperature chalcopyrite–molybdenite mineralization by the earlier wolframite mineralization. The obtained data indicate the significance of probable vertical movement of the ore formation zone during the multistage mineralization process for the development of certain sequences of formation of mineral assemblages observed in ore deposits.

Partitioning of volatile components (Cl, F, CO2) in water-saturated fluid-magmatic systems of various composition

The results of experimental studies of the behavior of volatile components (Cl, F, CO2 and H2O) in fluid-magmatic systems are presented. The maximum chlorine content in magmatic melts mainly depends on the composition of the melt and, to a lesser extent, on pressure (10300 MPa) and temperature (8001000C). The Cl content in the melt increases from 0.20.3 to 35 wt.% with increasing in the Ca content during the transition from polymerized granitoid to depolymerized basaltic melts. The pressure dependence of solubility has a maximum at a pressure of about 100200 MPa. A tendency of increasing in the Cl content and decreasing in the F content in the melt during the transition from acidic and alkaline to basaltic melts has been established. The maximum Cl content in the melt significantly increases from rhyolitic (up to 0.25 wt.%) to phonolitic (up to 0.85 wt.%) and dacitic (up to 1.2 wt.%) at temperatures of 10001200C and pressure of 200 MPa. The addition of CO2 to the system causes an increase in the Cl content in the melt by 2025 relative %, which is apparently associated with an increase in the Cl activity in the fluid. In this case, the H2O content in the melt decreases by ~ 0.51.0 wt.%. A strong effect of hydrolysis was shown in the interaction of an alumina-rich granitic melt with ~ 0.51N chloride fluid. This effect shows that at hypabyssal magmatic conditions (P = 100 MPa, T = 750C), the fluid is acidic (the pH after the experiment is ~ 11.5) and it is characterized by high dissolving power. It was established experimentally that as a result of the interaction of aqueous Na-K-Ca-chloride fluid of variable composition with granodioritic and granitic melts in the pressure range of ~ 100200 MPa and temperatures of 8201000C and with increasing in the total salt content, the Na and K replace Ca in the silicate melt, displacing the latter into the fluid, that is enriched in CaCl2 and is depleted in NaCl. Experimental results on the joint partitioning of Cl and F provide a quantitative basis for understanding the degassing processes in the course of the evolution of alkaline and basaltic magmas. They are important for assessing the extent of the removal of Cl and F into the earths atmosphere during volcanic activity and the effects of this removal on climate change.

The Tamunier gold deposit in the Northern Ural: Physicochemical formative conditions, ore and fluid sources, genesis

Research subject.This research study was aimed at investigating metasomatic minerals and ores in the Tamunier Deposit, which is located in the Northern Urals, at the Eastern side of the Tagil megazone within the Auerbach volcano-plutonic belt.Materials and methods.Well core samples were investigated using a complex of research methods, including optical and electron microscopy, X-ray spectral microanalysis, mineral geothermometry, thermobarogeochemistry (microthermometry, gas chromatography, determination of the salt composition of fluid inclusions in minerals) and isotope geochemistry (isotopes C, O, S, Sr, Pb).Results.A genetic model describing the formation of the Tamunier deposit was developed using the data obtained on its geological structure, mineral composition of metasomatites and ores, fluid formation mode, sources of ore matter and ore-bearing fluid. In the proposed model, the magmatogenic sodium chloride fluid carrying ore components and S is separated from the Auerbach complex at the depth of intrusion. Penetrating to the surface, this fluid interacts with the rocks of volcanic-sedimentary strata, thereby extracting a number of components, including CO2, S and Sr.Conclusion.Despite the presence of sulphide mineralization of hydrothermal-sedimentary genesis in the volcanogenic-sedimentary rock mass, the data obtained has allowed us to refer the gold-sulphide ores under study to magmatogenic-hydrothermal formations. The estimated P-T conditions (t= 100–370ºС andP= 0.4–0.6 kbar) and the shallow depth of the Tamunier field have shown its correspondence to the sub-epithermal level in the model of the porphyry-epithermal ore-magmatic system.

Geochemical studies of thermal waters from Kanlaon Volcano, Negros Island, Philippines

Kanlaon is a stratovolcano situated in central Negros Island, Philippines. It has a record of 30 eruptions since 1866 ranging from phreatic to phreatomagmatic (VEI = 1–2) events. Geothermal manifestations in Kanlaon Volcano are evidenced by the presence of hot springs, boiling mud pools, and warm rivers with temperatures up to 95 °C. It has developed a significant hydrothermal system within the volcanic edifice. Through time, it evolved into two distinct hydrothermal systems independent of each other. A mature hydrothermal system, represented by Pataan thermal area is characterized by neutral Na + K chloride (bicarbonate) fluids and an immature system, represented by Hagdan spring is characterized by the presence of acid-sulfate waters.Representative water samples were collected between 2014 and 2017 to further characterize the two systems. Chemical and sulfur isotopic analyses were performed on thermal waters to classify the samples that are linked to the co-existence of these two hydrothermal systems. Results show that thermal spring's pH ranges between 2.5 and 8.1 and conductivity ranges between 88 μS/cm to 3930 μS/cm. Based on their Cl-SO4-HCO3 relative abundances, the thermal waters are classified as acid sulfate, acid-sulfate chloride, neutral chloride and neutral bicarbonate waters.Temperatures of deep-water hydrothermal reservoirs were calculated using fluid-mineral geothermometers and correlated with available borehole temperatures. The Na-K-Mg geothermometer was used to evaluate equilibrium between water and reservoir rocks. Results show that the samples are not in equilibrium with the minerals in the reservoir. Temperature of equilibrium for the mature hydrothermal system was extrapolated to 270 °C based on available borehole temperatures. The linear trend towards the equilibrium temperature in the Na-K-Mg geothermometer can be explained by either groundwater/meteoric dilution. This is consistent with the light sulfur isotopic signatures between δ34S = −3.4‰ and + 1.2‰ of the mature hydrothermal system (Mambucal), which imply that the origin of sulfates is linked to surficial oxidation of H2S or dilution and mixing of meteoric water. On the other hand, immature hydrothermal system (Hagdan) shows a significantly higher sulfur isotopic composition (δ34S = +8.2‰), which could either result from the disproportionation of magmatic SO2 or from the hydrolysis of elemental sulfur at high temperature between 100 and 350 °C.

Strong impact of ion filtration on the isotopic composition of chlorine in young clay-rich oceanic sediment pore fluids

A collection of 34 pore fluids from young clay-rich sedimentary piles of the Shikoku basin on the Philippine oceanic plate at the front of the Nankai subduction zone, southeast of Japan, were analyzed for their chloride content and chlorine stable isotope composition (35Cl and 37Cl, reported as δ37Cl). These pore fluids are samples from IODP Sites C0011 and C0012, which penetrate deeper than 500 meters below the seafloor. At both sites, the δ37Cl values display a regular decrease with depth from about 0‰ (seawater value) at the seafloor to −8.5 and −6.5‰ respectively in hydrogeologically isolated, low permeability, sediment levels. At some depths, local deviations of up to 6‰ in δ37Cl interrupt the overall decreasing trends. They may be interpreted as the injection of external fluids into the sedimentary piles as a result of sedimentary levels with higher permeability. At the bottom of the sedimentary piles, the injected fluids, probably originating from the altered oceanic crust, systematically have δ37Cl values closer to seawater. Literature data indicate the display of downward trends of decreasing δ37Cl values of the pore fluids in many other young clay-rich sedimentary piles (Nankai Trough and the Japan Trench accretionary prisms, Black Ridge and Juan de Fuca Ridge flank). Here, we use conservation equations to demonstrate that these δ37Cl depth profiles can be modeled using the effect of the compaction of growing clay–rich sedimentary piles on the water and chlorides (including 35Cl and 37Cl isotopes). This modeling shows that a small isotope fractionation of chlorine isotopes, α37Cl/35Clexpulsed fluid-residual fluid, in the range of 1.006 to 1.001, may explain the observed negative δ37Cl chlorides at the bottom of the sedimentary piles. The complementary positive δ37Cl chlorides must accumulate at the top but are very likely erased by dilution with seawater chlorides across the seafloor interface. This range of chlorine isotope fractionation values is in agreement with the theory of ion filtration of Phillips and Bentley (1987) in which the mobility of chlorides through semi-permeable clay membrane is determined by ion repulsion. Based on this study, we show that young pore fluids in clay-rich sediments of the oceanic crust are 37Cl-depleted chloride reservoirs. They might be the source of 37Cl-depleted chloride fluids advected at mud volcanoes on the seafloor but do not seem to contribute largely to subduction zone magmatic, tectonic, metamorphic products where no such 37Cl-depleted chlorine is documented. This in turn is a strong argument to propose that most of the clay-rich sediment’s pore waters are released back into the ocean rather than subducted.

Hydrogeochemical Characterization of GeothermalWater in Arjuno-Welirang, East Java, Indonesia

Arjuno-Welirang Volcanic Complex (AWVC) is one of geothermal fields whichlocated in East Java province, Indonesia. It belongs to a Quarternary volcanic arc and has potential for development of electricity. The field is situated in a steep volcanic terrain and there are only few geothermal manifestations, i.e., hot springs, fumaroles, solfataras, steaming ground and hydrothermal alteration. This study aims to classify the type and source of geothermal fluid and to estimate the reservoir condition of Arjuno- Welirang geothermal system. Data are obtained from collecting water samples including hot springs, cold springs, river waters and rain water, then they are analyzed using ICP-AES, titration and ion chromatography.All thermal waters have temperatures from 39.5–53°C and weakly acidic pH (5.2–6.5). Cangar and Padusanhot springs show bicarbonate water, formed by steam condensing or groundwater mixing. On the other hand, Songgoriti shows Cl-HCO3 type, formed by dilution of chloride fluid by either groundwater or bicarbonate water during lateral flow. All of the waters represent immature waters, indicating no strong outflow of neutral Cl-rich deep waters in AWVC. Cl/B ratios show that all water samples have a similar mixing ratio, showing they are from common fluid sources. However, Padusan and Songgoriti have higher Cl/B ratios than Cangar, suggesting that geothermal fluids possibly have reacted with sedimentary rocks before ascending to the surface. All waters were possibly mixed with shallow groundwater and they underwent rock-water reactions at depth before ascending to the surface. An estimated temperatures reservoir calculated using CO2 geothermometer yielded temperatures of 262–263 °C based on collecting of fumarole gas at Mt. Welirang crater. According to their characteristics, Cangar and Padusan are associated with AWVC, while Songgoriti is associated with Mt. Kawi.

Characteristics and variations of sinters in the Coromandel Volcanic Zone: application to epithermal exploration

ABSTRACTThe Hauraki Goldfield of the Coromandel Volcanic Zone, North Island, New Zealand, hosts up to 19 known siliceous hot spring deposits, or sinters, some directly associated with Au–Ag ore bodies, in a Miocene–Pliocene, sub-aerial, calc-alkaline volcanic arc overlying Jurassic meta-sedimentary basement. Sinters are surface expressions of predominately adularia-sericite epithermal systems, potentially linked to Au–Ag mineralised conduits at depth. They provide a paleosurface marker to determine the level of erosion, and help determine zones of thermal fluid upflow and/or lateral outflow. Mapped sinters of the Coromandel Volcanic Zone are mainly affiliated with rhyolite domes, occur along structural corridors of the volcanic arc, and contain characteristic textures, mineralogy and pathfinder elements typical of near-neutral pH alkali chloride fluid discharge derived from convectively circulating magmatic fluids diluted by meteoric waters. Textures and trace element compositions of the Coromandel sinters are similar to those of the Taupo Volcanic Zone, New Zealand, and the Jurassic Au–Ag mining districts of the Deseado Massif, Argentine Patagonia. Thus, detailed mapping, textural analysis and trace-element studies demonstrate the prospecting potential of siliceous hot spring deposits for locating ore deposits, and in particular to help define proximal to distal positions relative to vent zones at the paleo-surface.

Chloride and Other Electrolyte Concentrations in Commonly Available 5% Albumin Products.

Use of hyperchloremic IV fluids for resuscitation in sepsis may be associated with increased mortality and use of renal replacement therapy. After crystalloids, 5% human albumin represents the second most common resuscitation fluid in the ICU. Its chloride concentration is rarely considered in the clinical setting. This study quantifies previously undocumented chloride concentrations of three 5% albumin solutions using biochemical analysis. We performed blinded analysis of the electrolyte concentration of albumin samples obtained directly from the national blood supplier (Canadian Blood Services). Two-tailed independent t tests were performed for all possible comparative analyses. Analysis of variance testing was performed for relevant three-way comparisons. Significance threshold was set at p less than 0.05. All samples were analyzed in the core laboratory at an academic hospital associated with McMaster University in Hamilton, Ontario, Canada. We analyzed 65 albumin samples from three available brands obtained through Canadian Blood Services. They include Plasbumin (n = 21), Alburex (n = 24), Octalbin (n = 20). Laboratory technologists blinded to product identification measured the concentration of electrolytes, extended electrolytes, lactate, and albumin of each sample using the Abbott ARCHITECT c8000 chemistry analyzer. The mean chloride concentration of Plasbumin, Alburex, and Octalbin, respectively, were 109.4 mmol/L (SD, 1.3), 123.6 mmol/L (SD, 1.3), and 136.8 mmol/L (SD, 0.4). The mean sodium concentration of Plasbumin, Alburex, and Octalbin, respectively, were 139.6 mmol/L (SD, 1.6), 137.3 mmol/L (SD, 2.2), and 149.4 mmol/L (SD, 0.5). The chloride and sodium concentration differed significantly for all two-way comparisons (p < 0.0001) and multiple comparison testing (p < 0.0001). This study is the first to identify and document a statistically significant variability in the chloride concentration of available 5% albumin products. This study has also informed a pilot randomized controlled trial examining the effect of administering high chloride versus low chloride fluids in critically ill patients with sepsis.

Geology, mineralization, and fluid inclusion characteristics of the Kashkasu W-Mo-Cu skarn deposit associated with a high-potassic to shoshonitic igneous suite in Kyrgyzstan, Tien Shan: Toward a diversity of W mineralization in Central Asia

The Kashkasu deposit is part of the subduction-related Late Paleozoic (Late Carboniferous) metallogenic belt of Tien Shan. It is associated with a multiphase monzodiorite-monzonite-granodiorite-granite pluton of the magnetite-series high-K calc-alkaline to shoshonitic igneous suite. The deposit contains zones of W-Mo-Cu oxidized prograde and retrograde skarns, with abundant andraditic garnet, magnetite, locally scapolite and K-feldspar, as well as scheelite, chalcopyrite, and molybdenite. Skarns are overprinted by quartz-carbonate-sericite (phyllic alteration) zones with scheelite and sulfides.Prograde calcic skarn and initial retrograde skarns were formed from a high temperature (650 °C to 450–550 °C), high pressure (2000 bars to 600–900 bars) magmatic-hydrothermal low- to high-salinity aqueous chloride fluid. The gradual fluid evolution was interrupted by the intrusion of granodiorite and likely associated release of low-salinity (∼7–8 wt% NaCl equiv.) fluid. Ascent of this fluid to shallower levels and/or its cooling to 400–500 °C has resulted in phase separation into low-salinity (2.1–3.1 wt% NaCl equiv.) vapor and coexisting brine (35–40 wt% NaCl equiv.). The boiling was coincident with most intense scheelite deposition in retrograde skarn. Later retrograde skarn assemblages were formed from a gaseous, low- to moderate-salinity (3.4–8.1 wt% NaCl equiv.) fluid and then from high salinity (37–42 wt% NaCl equiv.) aqueous chloride fluids, the latter being enriched in Ca (17–20 wt% CaCl2) that could also affect scheelite deposition. Another cycle of fluid exsolution from crystallizing magma corresponded to quartz-carbonate-sericite-scheelite-sulfide (phyllic) alteration stage, with the early low-salinity (5.3–8.4 wt% NaCl-equiv.) fluid followed by later high-salinity (33.5–38.2 wt% NaCl-equiv.) fluid. The sulfur isotope data (δ34S = +5.1 to +9.0) suggest significant sulfur sourcing from sedimentary rocks enriched in seawater sulfate, possibly evaporites.

Fluids in Sepsis and Septic Shock (FISSH): protocol for a pilot randomised controlled trial

IntroductionObservational evidence suggests physiological benefits and lower mortality with lower chloride solutions; however, 0.9% saline remains the most widely used fluid worldwide. Given uncertainty regarding the association of lower chloride...

The effect of CO2 on the solubility of aqueous chloride fluid in dacite, phonolite, and rhyolite melts

The solubility of H2O–CO2–Cl-containing fluids of various concentrations (0, 3, 10, and 23 wt % of HCl and from 0 to ~8–15 wt % of CO2) in dacite, phonolite, and rhyolite melts at 1000°C and 200 MPa was studied in experiments. It was shown that the Cl concentration in the melt increased substantially from rhyolite to phonolite and dacite (up to 0.25, 0.85, and 1.2 wt %, respectively). The introduction of CO2 into the system resulted in an increase in the Cl content in the melt composition by 20–25%. One may suppose that Cl reactivity in a fluid increases in the presence of CO2 to cause growth of the Cl content in the melt. The introduction of CO2 into the system considerably affects the content of H2O in aluminosilicate melts as well. Thus, the addition of CO2 decreases the H2O content in the melt by ~0.5–1.0 wt %. The decrease in the H2O content in an aluminosilicate melt is probably caused by fluid dilution with CO2 resulting in a decrease in the H2O mole fraction and fugacity in the fluid.

Dissolving dolomite in a stable UHP mineral assemblage: Evidence from Cal-Dol marbles of the Dora-Maira Massif (Italian Western Alps)

In deep and cold subduction such as that experienced by the UHP Units of the Western Alps, carbon dissolution is a relevant mechanism for carbon transfer from the slab into the mantle. The UHP impure Cal-Dol-marbles from the Dora-Maira Massif are studied to investigate the poorly known evolution of dolomite during deep subduction. Dolomite shows four stages of growth, from pre-Alpine to early-retrograde Alpine, coupled with chemical variations and distinct included mineral assemblages. To explain the evidence for growth and partial reabsorption of dolomite through HP prograde, UHP peak, and UHP early-retrograde Alpine metamorphism, a chemically simple marble (Cal, Dol, Di, Fo, and retrograde Atg, Tr, Mg-Chl) has been studied in detail. Microstructural relationships, coupled with mineral chemistry, indicate the growth of the assemblage dolomite+diopside+forsterite±aragonite during HP prograde, UHP peak, and UHP early-retrograde evolution. Mixed-volatile P-T projection modeled in the simple CaO-(FeO)-MgO-SiO 2 -H 2 O-CO 2 system and T - P - X CO 2 petrogenetic grids and pseudosections predict the prograde (1.7 GPa, 560 °C) growth of dolomite in equilibrium with diopside and forsterite through the breakdown of antigorite+aragonite. In a H 2 O-CO 2 -saturated system, the subsequent HP-UHP evolution is predicted in the Di+Fo+Dol+Arg stability field in equilibrium with a dominantly aqueous COH fluid [ 0 . 0003 X CO 2 0 . 0008 ], whose composition is internally buffered by the equilibrium assemblage. Thermodynamic modeling indicates that neither the consumption nor the growth of new dolomite generations at UHP conditions can have been induced by metamorphic reactions. The abundant primary H 2 O+Cal+Dol+Cl-rich Tr+Cl-rich Tlc±chloride fluid inclusions present in UHP Cpx indicate that a dominantly aqueous, saline (salinity >26.3 wt% of NaCl eq ) COH fluid, containing Ca, Mg, and Si as dissolved cations was present during the growth of the UHP assemblage Dol+Cpx+Ol+Arg. The complex zoning of dolomite is therefore interpreted as due to protracted episodes of dissolution and precipitation in saline aqueous fluids at HP/UHP conditions. Kinetics of dolomite dissolution in aqueous fluids is poorly known, and experimental and thermodynamic data under HP conditions are still lacking. Data on calcite indicate that dissolution at HP is enhanced by a prograde increase in both P and T , by high salinity in aqueous fluids, and/or low-pH conditions. In the studied marble, the P-T path and the occurrence of free high-saline fluids represent favorable conditions: (1) for the inferred dissolution-precipitation processes of the stable dolomite in a closed system, and (2) for possible migration of the dissolved carbonate, if the system would have been open during subduction.

Chlorine partitioning between melt and aqueous chloride fluid phase during granite magma degassing. Part II. Crystallization-induced degassing of melts

An empirical computer model was developed to describe granite magma degassing and the partitioning behavior of Cl between melts and aqueous chloride fluids that formed during eutectic isobaric crystallization of magmas at pressures from 4 to 0.4 kbar and a temperature of 800 ± 25°C. This model is the extensions of the earlier model describing the decompression degassing of granite melts (Lukanin, 2015). The numerical modeling was performed for both closed-system conditions, when fluid remains in the system, and open-system conditions, when fluid is removed from the system. The results of numerical modeling revealed the main factors controlling the behavior of Cl during crystallization-induced degassing, such as the initial contents of Cl and H2O of the melts, pressure, and the degree of system openness. At high pressures (>1.6 kbar), isobaric crystallization is accompanied by a decrease in the concentrations of Cl in the melt (CClm) and fluid phase (CClfl). This tendency becomes even more pronounced in an open-system with increasing pressure and initial Cl content. A decrease in pressure in the range of 1.62–0.85 kbar results in a drastic change in the Cl behavior: the trend of CClfl and CClfl decrease dominating during crystallization at high pressures changes to the opposite. At low pressures (<0.85 kbar), the enrichment of the residual melts and released fluids in Cl leads at a certain stage of crystallization to the formation of a heterogeneous fluid consisting of two immiscible aqueous chloride phases, a waterdominated aqueous phase and a chloride-rich liquid (brine).

The formation environment of potassic‐chloro‐hastingsite in the nakhlites MIL 03346 and pairs and NWA 5790: Insights from terrestrial chloro‐amphibole

AbstractPotassic‐chloro‐hastingsite has been found in melt inclusions in MIL 03346, its paired stones, and NWA 5790. It is some of the most chlorine‐rich amphibole ever analyzed. In this article, we evaluate what crystal chemistry, terrestrial analogs, and experiments have shown about how chlorine‐dominant amphibole (chloro‐amphibole) forms and apply these insights to the nakhlites. Chloro‐amphibole is rare, with about a dozen identified localities on Earth. It is always rich in potassium and iron and poor in titanium. In terrestrial settings, its presence has been interpreted to result from medium to high‐grade alteration (&gt;400 °C) of a protolith by an alkali and/or iron chloride‐rich aqueous fluid. Ferrous chloride fluids exsolved from mafic magmas can cause such alteration, as can crustal fluids that have reacted with rock and lost H2O in preference to chloride, resulting in concentrated alkali chloride fluids. In the case of the nakhlites, an aqueous alkali‐ferrous chloride fluid was exsolved from the parental melt as it crystallized. This aqueous chloride fluid itself likely unmixed into chloride‐dominant and water‐dominant fluids. Chloride‐dominant fluid was trapped in some melt inclusions and reacted with the silicate contents of the inclusion to form potassic‐chloro‐hastingsite.

The Borinquen geothermal system (Cañas Dulces caldera, Costa Rica)

The geotectonic location of Costa Rica has allowed the development of an active volcanic arc, geological context associated with hydrothermal systems with geothermal potential. In the northwest of the country, on the Pacific slope of the Rincon de la Vieja volcano, inside the Cañas Dulces caldera, the presence of thermal manifestations motivated the development of geoscientific studies that culminated with the drilling of 4 geothermal exploration wells to depths of 2078–2594m, as part of the research that seeks to corroborate the existence of a commercially geothermal reservoir. A date has explored an area of 31km2 known as Borinquen where information on lithostratigraphy, mineralogy, electric resistivity and thermal gradients, as well as on the geochemical and isotopic composition of the fluids derived from the meteoric water, surface hydrothermal manifestation and exploration wells, was obtained. The distribution of the secondary mineral assemblages observed in the exploration wells suggests an increase in temperature with depth, which is confirmed by the distribution of the thermal gradient. The geoelectric structure hints at the existence of a cap rock and a geothermal reservoir, and the geochemistry and isotopic composition of the samples obtained from the exploration wells reveal the existence of neutral sodium chloride fluids with high enthalpy. This suggests exploitation could be economically viable, particularly in light of comparisons with similar reservoirs already being exploited in the neighbouring calderas of San Vicente and Guayabo. Taking into account all the available information, we provide a conceptual model of the Borinquen geothermal area that explains the main elements of its high enthalpy geothermal system – heat source, distribution of the thermal anomaly, recharge zone, reservoir, cap rock, main flow paths and flow directions. This will be useful as a guide for the exploration and future development and exploitation of this geothermal resource.