Geochemistry Of Hot Springs Research Articles

Geochemistry of hot-springs at the SuSu Knolls hydrothermal field, Eastern Manus Basin: Advanced argillic alteration and vent fluid acidity

Abstract SuSu Knolls is an area of ongoing magmatic activity and recent volcanism located in the back-arc spreading environment of the Manus Basin in the Bismarck Sea, Papua New Guinea. In 2006, hydrothermal fluids were collected from three areas of submarine hot-spring venting and analyzed for the chemical and isotopic composition of major and trace species. Fluids were characterized by temperatures that varied from 226–325 °C, and formed grey to black smoke as they mixed with bottom seawater. The compositions of seawater derived vent fluids are regulated by the relative contributions of fluid-rock and fluid-sediment interaction, phase separation, and the addition of volatiles from magmatic degassing. In addition to phase separation, leaching of Cl from felsic rocks that compose the lithosphere in back-arc environments may produce Cl concentrations in excess of seawater values. The measured pH25°C of SuSu Knolls smoker fluids varied from 1.5–3.7, a range that includes values substantially more acidic than typically observed in fluids at mid-ocean ridge spreading centers. Late stage addition of magmatic volatiles in the shallow seafloor is directly responsible for the most acidic fluids (pH25°C values below 2). In contrast, the acidity of vent fluids characterized by pH25°C values between 2 and 3 is not the direct result of the direct addition of magmatically-derived acidic species. Instead, the pH of these fluids likely reflects reaction with rocks that were previously altered by highly acidic magmatic fluids to an advanced argillic alteration assemblage containing quartz-illite-pyrophyllite-anhydrite ± alunite in hydrothermal upflow zones. Fluids that do not react with advanced argillic alteration assemblages during upflow have measured pH25°C values between 3 and 4.

Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs.

The geochemistry of hot springs and the availability of oxidants capable of supporting microbial metabolisms are influenced by subsurface processes including the separation of hydrothermal fluids into vapor and liquid phases. Here, we characterized the influence of geochemical variation and oxidant availability on the abundance, composition, and activity of hydrogen (H2 )-dependent chemoautotrophs along the outflow channels of two-paired hot springs in Yellowstone National Park. The hydrothermal fluid at Roadside East (RSE; 82.4°C, pH 3.0) is acidic due to vapor-phase input while the fluid at Roadside West (RSW; 68.1°C, pH 7.0) is circumneutral due to liquid-phase input. Most chemotrophic communities exhibited net rates of H2 oxidation, consistent with H2 support of primary productivity, with one chemotrophic community exhibiting a net rate of H2 production. Abundant H2 -oxidizing chemoautotrophs were supported by reduction in oxygen, elemental sulfur, sulfate, and nitrate in RSW and oxygen and ferric iron in RSE; O2 utilizing hydrogenotrophs increased in abundance down both outflow channels. Sequencing of 16S rRNA transcripts or genes from native sediments and dilution series incubations, respectively, suggests that members of the archaeal orders Sulfolobales, Desulfurococcales, and Thermoproteales are likely responsible for H2 oxidation in RSE, whereas members of the bacterial order Thermoflexales and the archaeal order Thermoproteales are likely responsible for H2 oxidation in RSW. These observations suggest that subsurface processes strongly influence spring chemistry and oxidant availability, which in turn select for unique assemblages of H2 oxidizing microorganisms. Therefore, these data point to the role of oxidant availability in shaping the ecology and evolution of hydrogenotrophic organisms.

Geochemistry of hot springs in the Ie Seu’um hydrothermal areas at Aceh Besar district, Indonesia

Indonesia geothermal resources are the largest in the world, about 40 percent of the total geothermal resources worldwide with a potential energy of 28,617 MW. Geothermal energy is one of the renewable energy in the world that can be developed sustainably. This kind of energy is not only environmentally friendly but also highly prospective compared to fossil energy. One of the potential geothermal energy in Indonesia is Seulawah Agam geothermal field with some manifestation areas. The fluid type of Ie Seu’um manifestation was chloride (Cl-) obtained from the ternary diagram Cl--SO42--HCO3-, using UV-Vis spectrophotometry, argentometry and acidimetry method. The reservoir range temperature was 188,7 ± 9,3°C calculated using geothermometer Na-K-Ca, Na-K Fournier and Na-K Giggenbach by applying Atomic Absorption Spectroscopy method. This data processing was carried out using liquid chemistry plotting spreadsheet version 3 powell geoscience Ltd.3 September 2012 by Powell & Cumming. The potential in the geothermal manifestation of Ie Seu’um was estimated about 50-100 MW (medium enthalpy).

Chemical characteristic of landslide clay inferred from geochemistry of hot springs in the northern part of NE Japan.

Chemical characteristic of landslide clay inferred from geochemistry of hot springs in the northern part of NE Japan.

Formation environment of carbonate concretions inferred from geochemistry of hot springs in the northern part of Tohoku region.

Formation environment of carbonate concretions inferred from geochemistry of hot springs in the northern part of Tohoku region.

Geochemistry of hot springs in the Tengchong hydrothermal areas, Southwestern China

As an important volcanic geothermal region in China, Tengchong belongs to the Mediterranean–Himalayas geothermal belt and is characterized by wide distribution of volcanic rocks. Fifty-eight hydrothermal areas have been identified in Tengchong, among which the Rehai hydrothermal system is the most geothermally active. The geothermal waters from Rehai are mainly Na-HCO3-Cl and Na-HCO3 types, whereas those from the other hydrothermal areas are mainly Na-HCO3, Na-Ca-HCO3, Ca-HCO3, Ca-Mg-HCO3, Mg-Na-Ca-HCO3, and Mg-Ca-HCO3 types. Both quartz geothermometer and K-Mg geothermometer indicate that the Rehai geothermal field has higher subsurface temperatures than the other hydrothermal areas. Except for three Rehai samples, most geothermal water samples collected from Tengchong are far from the full equilibrium line in Giggenbach's triangular diagram, suggesting that the complete chemical re-equilibrium has not been achieved as these geothermal waters flow upward from reservoirs towards spring vents and possibly mix with cooler waters. Statistical analysis shows that Cl, B, Li, Rb, and Cs are the characteristic constituents of the Tengchong geothermal waters, and the good linear relations among these elements in the Rehai geothermal waters reflect the existence of a deep parent geothermal liquid (PGL) below Rehai. An enthalpy-chloride diagram of the Rehai geothermal waters suggests that the parent geothermal liquid has Cl−concentration of 291mg/L and enthalpy of 1495J/g. The PGL ascends to the surface through different channels and may cool by conduction of heat to reservoir host rocks, by boiling, or by mixing with cooler shallow groundwaters.

Gas isotopes and geochemistry of hot springs in Hengjing, Jiangxi Province

With emphasis on gas isotopes and geochemistry as well as hydrogeochemistry, a field investigation has been carried out in Hengjing geothermal area, south Jiangxi Province of south-eastern China. The water chemistry of the geothermal waters indicates their local meteoric water origin, whereas their gas composition and carbon and helium isotopes reveal that some gases in the geothermal waters have mantle origin.

Geochemistry of hot springs and fumarolic gases from the Banda Arc

Geothermometry carried out on hot springs occurring on the volcanic non-active Islands of Ambon and Haruku indicates minimum subsurface temperatures of 180°C; for Alor Island we obtained a temperature of 170°C. The hydrothermal systems of these islands are likely crack and fault dominated. Hot springs on the islands with active volcanism indicate subsurface temperatures of 180 to 250°C.The chemical and isotopic compositions of fumarolic gases from the active volcanoes Banda Api in the Banda Archipelago, Serawerna on Teon, Wurlali on Damar and Ili Lewotolo on Lomblen are reported here for the first time. The measured fumarolic gas temperatures ranged from 98°C to 170°C for Banda Api, Laworkawra, Legatala, Serawerna, Wurlali and Sirung volcanoes and reached 490°C for Ili Lewotolo volcano. The main gas components are H2O, CO2 and SO2; CO2 predominates over (SO22 + H2S). The calculated gas equilibrium temperature for Wurlali is 700°C and for Ili Lewotolo more than 1000°C.Stable carbon isotope data for Wurlali (δ13C = −3.3 % 0) and for Ili Lewotolo (δ13C = −2.9 % 0) volcanoes are similar to those for other Indonesian volcanoes. The bulk sulfur is relatively rich in the heavy isotope. The 3He/4He (R/RA) ratios vary between 1.0 and 3.6, which is low for subduction related volcanoes. A contribution from continental crust or sediment-derived radiogenic 4He is suggested.

Overview of Geothermal Energy Developments: ABSTRACT

Exploration for geothermal resources includes evaluation of the volcanic history, regional geology and hydrology, geochemistry of hot springs, and use of selected geophysical methods to determine temperature, heat flow, and structure of prospective areas. Geothermal energy is primarily used for electric power generation. At the Geysers field in northern California, geothermal energy has proved to be a viable, mechanically reliable, and environmentally acceptable resource. The field competes economically with alternative forms of power generation such as oil, gas, nuclear, and hydroelectric. The Geysers field is an example of a vapor-dominated geothermal reservoir. The field produces 630 Mw, with a total capacity estimated to be about 2,000 Mw. It is the only geothermal field used to generate significant quantities of electricity in the United States. Other areas experiencing active development are the Imperial Valley of California, Baca area of New Mexico, and Roosevelt area of Utah. Overall, plans have been announced for nine power plants at seven sites, with a total generating capacity of 300 Mw. The new areas are all liquid-dominated systems. The Department of Energy estimates that 15,000 to 20,000 Mw of geothermal power can be developed in the western United States in the next 2 decades. With improved exploration, drilling, and utilization technology, it has been estimated that several times this amount of power can be developed, provided that delays due to environmental and legal/institutional issues can be resolved. End_of_Article - Last_Page 761------------