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Sample records for logatchev hydrothermal sites

  1. Organic Analysis of Peridotite Rocks from the Ashadze and Logatchev Hydrothermal Sites

    PubMed Central

    Bassez, Marie-Paule; Takano, Yoshinori; Ohkouchi, Naohiko

    2009-01-01

    This article presents an experimental analysis of the organic content of two serpentinized peridotite rocks of the terrestrial upper mantle. The samples have been dredged on the floor of the Ashadze and Logatchev hydrothermal sites on the Mid-Atlantic Ridge. In this preliminary analysis, amino acids and long chain n-alkanes are identified. They are most probably of biological/microbial origin. Some peaks remain unidentified. PMID:19742180

  2. Organic analysis of peridotite rocks from the Ashadze and Logatchev hydrothermal sites.

    PubMed

    Bassez, Marie-Paule; Takano, Yoshinori; Ohkouchi, Naohiko

    2009-06-01

    This article presents an experimental analysis of the organic content of two serpentinized peridotite rocks of the terrestrial upper mantle. The samples have been dredged on the floor of the Ashadze and Logatchev hydrothermal sites on the Mid-Atlantic Ridge. In this preliminary analysis, amino acids and long chain n-alkanes are identified. They are most probably of biological/microbial origin. Some peaks remain unidentified. PMID:19742180

  3. Organic analysis of peridotite rocks from the Ashadze and Logatchev hydrothermal sites.

    PubMed

    Bassez, Marie-Paule; Takano, Yoshinori; Ohkouchi, Naohiko

    2009-07-03

    This article presents an experimental analysis of the organic content of two serpentinized peridotite rocks of the terrestrial upper mantle. The samples have been dredged on the floor of the Ashadze and Logatchev hydrothermal sites on the Mid-Atlantic Ridge. In this preliminary analysis, amino acids and long chain n-alkanes are identified. They are most probably of biological/microbial origin. Some peaks remain unidentified.

  4. Sulphur Cycling at the Mid-Atlantic Ridge: Isotopic Evidence From the Logatchev and Turtle Pits Hydrothermal Fields

    NASA Astrophysics Data System (ADS)

    Eickmann, B.; Strauss, H.; Koschinsky, A.; Kuhn, T.; Petersen, S.; Schmidt, K.

    2005-12-01

    Mid-ocean ridges and associated hydrothermal vent systems represent a unique scenario in which the interaction of hydrosphere, lithosphere and biosphere and the related element cycling can be studied. Sulphur participates in inorganic and microbially driven processes and plays, thus, an important role at these vent sites. The sulphur isotopic compositions of different sulphur-bearing minerals as well as dissolved sulphur compounds provide a tool for identifying the sulphur source and pertinent processes of sulphur cycling. Here, we present sulphur isotope data from an ongoing study of the Logatchev hydrothermal field at 14°45' N and the Turtle Pits hydrothermal field at 4°48' S. The former is located in 2900 to 3060 m water depth, hosted by ultramafic rocks, while the latter is situated in 2990 m water depth, hosted by basaltic rocks. Different metal sulphides (chalcopyrite, pyrite, pyrrhotite, various copper sulphides), either particles from the emanating hot fluid itself or pieces of active and inactive black smokers, display δ34S values between +2 and +9 ‰. So far, no significant difference is discernible between mineral precipitates from both hydrothermal fields. However, differences exist between different generations of sulphide precipitates. Based on respective data from other sites of hydrothermal activity at mid-ocean ridges, this sulphur isotope range suggests that sulphur in the hydrothermal fluid and mineral precipitates represents a mixture between mantle sulphur and reduced seawater sulphate. Anhydrite precipitates from hydrothermal chimneys, located inside sulphide conduits, and obvious late stage gypsum needles from voids, yielded sulphur isotope values between +17.5 and +20.0 ‰. This clearly identifies seawater sulphate as the principal sulphur source. Variable, but generally low abundances of sulphide and sulphate in differently altered mafic and ultramafic rocks point to a complex fluid-rock interaction. Sulphur isotope values for total

  5. Off-axis Submarine Massive Sulfide accumulation at the fault-controlled Logatchev 1 hydrothermal field, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Andersen, Christine; Theissen-Krah, Sonja; Hannington, Mark

    2016-04-01

    The largest Submarine Massive Sulfide (SMS) deposits in Mid-ocean ridge settings are found along slow-spreading ridges, where tectonic processes dominate and long-lived faults control the circulation of hydrothermal fluids through the oceanic crust. Here we combine results from 2D fluid flow simulations of the off-axis (8km), fault-controlled, high-T Logatchev 1 hydrothermal field (LHF1) at the Mid-Atlantic Ridge with data on vent fluid chemistry and the associated SMS deposit, which give insights about its accumulation history. Modeled high vent temperatures of 360°C, as measured at the active LHF1, result in a total integrated mass-flow rate through the seafloor of ~36 kg/sec scaled to 28 vent orifices of 10x10cm, located in the 7 known high-T sites at the LHF1. About 42% of the vent fluids are hotter than 350°C, the minimum temperature required for efficient metal transport, with a mass-flow rate of 13 kg/sec. This corresponds to ~400 kilotons of potentially SMS-forming hydrothermal fluids leaving the vent field per year. Combined with a total H2S-SiO2-metal (Zn+Cu+Fe) concentration of 732 ppm, measured in the LHF1 vent fluids, this makes a flux of ~300 t of hydrothermal precipitates per year. The SMS deposit at LHF1 has been dated to 58.200 years and has an estimated tonnage of 135 kilotons. Applying the above modeled annual discharge rate over the dated time period, results in an SMS accumulation efficiency of ~0.8% for the SMS deposit at the Logatchev 1 field, which fits the range of estimated global average for MORs between <0.3% and 3%. Our predicted depositional efficiency is based on numerical modeling, which simulates continuous and ideal venting. Realistically, venting at LHF1 might well have been fluctuating, including periods of low temperature discharge, where metal transport is insufficient or periods of inactivity, compensated by periods with a higher depositional efficiency than 0.8%. Such fluctuations could have been caused by variations in

  6. In situ chemistry and microbial community compositions in five deep-sea hydrothermal fluid samples from Irina II in the Logatchev field.

    PubMed

    Perner, Mirjam; Gonnella, Giorgio; Hourdez, Stephane; Böhnke, Stefanie; Kurtz, Stefan; Girguis, Peter

    2013-05-01

    We present data on the co-registered geochemistry (in situ mass spectrometry) and microbiology (pyrosequencing of 16S rRNA genes; V1, V2, V3 regions) in five fluid samples from Irina II in the Logatchev hydrothermal field. Two samples were collected over 24 min from the same spot and further three samples were from spatially distinct locations (20 cm, 3 m and the overlaying plume). Four low-temperature hydrothermal fluids from the Irina II are composed of the same core bacterial community, namely specific Gammaproteobacteria and Epsilonproteobacteria, which, however, differs in the relative abundance. The microbial composition of the fifth sample (plume) is considerably different. Although a significant correlation between sulfide enrichment and proportions of Sulfurovum (Epsilonproteobacteria) was found, no other significant linkages between abiotic factors, i.e. temperature, hydrogen, methane, sulfide and oxygen, and bacterial lineages were evident. Intriguingly, bacterial community compositions of some time series samples from the same spot were significantly more similar to a sample collected 20 cm away than to each other. Although this finding is based on three single samples only, it provides first hints that single hydrothermal fluid samples collected on a small spatial scale may also reflect unrecognized temporal variability. However, further studies are required to support this hypothesis.

  7. Biogeographical distribution of Rimicaris exoculata resident gut epibiont communities along the Mid-Atlantic Ridge hydrothermal vent sites.

    PubMed

    Durand, Lucile; Roumagnac, Marie; Cueff-Gauchard, Valérie; Jan, Cyrielle; Guri, Mathieu; Tessier, Claire; Haond, Marine; Crassous, Philippe; Zbinden, Magali; Arnaud-Haond, Sophie; Cambon-Bonavita, Marie-Anne

    2015-10-01

    Rimicaris exoculata is a deep-sea hydrothermal vent shrimp whose enlarged gill chamber houses a complex trophic epibiotic community. Its gut harbours an autochthonous and distinct microbial community. This species dominates hydrothermal ecosystem megafauna along the Mid-Atlantic Ridge, regardless of contrasting geochemical conditions prevailing in them. Here, the resident gut epibiont community at four contrasted hydrothermal vent sites (Rainbow, TAG, Logatchev and Ashadze) was analysed and compiled with previous data to evaluate the possible influence of site location, using 16S rRNA surveys and microscopic observations (transmission electron microscopy, scanning electron microscopy and fluorescence in situ hybridization analyses). Filamentous epibionts inserted between the epithelial cell microvilli were observed on all examined samples. Results confirmed resident gut community affiliation to Deferribacteres, Mollicutes, Epsilonproteobacteria and to a lesser extent Gammaproteobacteria lineages. Still a single Deferribacteres phylotype was retrieved at all sites. Four Mollicutes-related operational taxonomic units were distinguished, one being only identified on Rainbow specimens. The topology of ribotype median-joining networks illustrated a community diversification possibly following demographic expansions, suggesting a more ancient evolutionary history and/or a larger effective population size at Rainbow. Finally, the gill chamber community distribution was also analysed through ribotype networks based on sequences from R. exoculata collected at the Rainbow, Snake Pit, TAG, Logatchev and Ashadze sites. Results allow the refining of hypotheses on the epibiont role and transmission pathways.

  8. Biogeographical distribution of Rimicaris exoculata resident gut epibiont communities along the Mid-Atlantic Ridge hydrothermal vent sites.

    PubMed

    Durand, Lucile; Roumagnac, Marie; Cueff-Gauchard, Valérie; Jan, Cyrielle; Guri, Mathieu; Tessier, Claire; Haond, Marine; Crassous, Philippe; Zbinden, Magali; Arnaud-Haond, Sophie; Cambon-Bonavita, Marie-Anne

    2015-10-01

    Rimicaris exoculata is a deep-sea hydrothermal vent shrimp whose enlarged gill chamber houses a complex trophic epibiotic community. Its gut harbours an autochthonous and distinct microbial community. This species dominates hydrothermal ecosystem megafauna along the Mid-Atlantic Ridge, regardless of contrasting geochemical conditions prevailing in them. Here, the resident gut epibiont community at four contrasted hydrothermal vent sites (Rainbow, TAG, Logatchev and Ashadze) was analysed and compiled with previous data to evaluate the possible influence of site location, using 16S rRNA surveys and microscopic observations (transmission electron microscopy, scanning electron microscopy and fluorescence in situ hybridization analyses). Filamentous epibionts inserted between the epithelial cell microvilli were observed on all examined samples. Results confirmed resident gut community affiliation to Deferribacteres, Mollicutes, Epsilonproteobacteria and to a lesser extent Gammaproteobacteria lineages. Still a single Deferribacteres phylotype was retrieved at all sites. Four Mollicutes-related operational taxonomic units were distinguished, one being only identified on Rainbow specimens. The topology of ribotype median-joining networks illustrated a community diversification possibly following demographic expansions, suggesting a more ancient evolutionary history and/or a larger effective population size at Rainbow. Finally, the gill chamber community distribution was also analysed through ribotype networks based on sequences from R. exoculata collected at the Rainbow, Snake Pit, TAG, Logatchev and Ashadze sites. Results allow the refining of hypotheses on the epibiont role and transmission pathways. PMID:26324855

  9. Geochemistry of vent fluid particles formed during initial hydrothermal fluid-seawater mixing along the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Klevenz, Verena; Bach, Wolfgang; Schmidt, Katja; Hentscher, Michael; Koschinsky, Andrea; Petersen, Sven

    2011-10-01

    We present geochemical data of black smoker particulates filtered from hydrothermal fluids with seawater-dilutions ranging from 0-99%. Results indicate the dominance of sulphide minerals (Fe, Cu, and Zn sulphides) in all samples taken at different hydrothermal sites on the Mid-Atlantic Ridge. Pronounced differences in the geochemistry of the particles between Logatchev I and 5°S hydrothermal fields could be attributed to differences in fluid chemistry. Lower metal/sulphur ratios (Me/H2S < 1) compared to Logatchev I result in a larger amount of particles precipitated per liter fluid and the occurrence of elemental sulphur at 5°S, while at Logatchev I Fe oxides occur in larger amounts. Systematic trends with dilution degree of the fluid include the precipitation of large amounts of Cu sulphides at a low dilution and a pronounced drop with increasing dilution. Moreover, Fe (sulphides or oxides) precipitation increases with dilution of the vent fluid by seawater. Geochemical reaction path modeling of hydrothermal fluid-seawater mixing and conductive cooling indicates that Cu sulphide formation at Logatchev I and 5°S mainly occurs at high temperatures and low dilution of the hydrothermal fluid by seawater. Iron precipitation is enhanced at higher fluid dilution, and the different amounts of minerals forming at 5°S and Logatchev I are thermodynamically controlled. Larger total amounts of minerals and larger amounts of sulphide precipitate during the mixing path when compared to the cooling path. Differences between model and field observations do occur and are attributable to closed system modeling, to kinetic influences and possibly to organic constituents of the hydrothermal fluids not accounted for by the model.

  10. Chemical signatures from hydrothermal venting on slow spreading ridges

    NASA Astrophysics Data System (ADS)

    Edmonds, Henrietta N.

    At least 24 sites of active venting have been confirmed on slow and ultraslow spreading ridges, with dozens more indicated on the basis of hydrothermal plume distributions and/or dredge recovery of massive sulfides. Fluid chemistry data have been published for 13 sites: 8 on the northern Mid-Atlantic Ridge, 3 on the southern Mid-Atlantic Ridge, and 2 on the Central Indian Ridge. Three of these 13 sites (Rainbow, Logatchev, and Lost City) are known to be hosted in ultramafic terrain, and their fluid chemistries reflect the influence of serpentinization reactions, including elevated hydrogen and methane, and low silica concentrations. This brief review presents the published fluid chemistry for all 13 sites, including time series where available, and demonstrates the diversity of chemical compositions engendered by the myriad settings (near and off axis, young volcanic to ultramafic terrain, and depths up to 4100 m) of hydrothermal systems on slow and ultraslow spreading ridges.

  11. Hydrothermal mixing: Fuel for life in the deep-sea

    NASA Astrophysics Data System (ADS)

    Hentscher, M.; Bach, W.; Amend, J.; McCollom, T.

    2009-04-01

    Deep-sea hydrothermal vent systems show a wide range of fluid compositions and temperatures. They reach from highly alkaline and reducing, like the Lost City hydrothermal field, to acidic and reducing conditions, (e. g., the Logatchev hydrothermal field) to acidic and oxidizing conditions (e. g., island arc hosted systems). These apparently hostile vent systems are generally accompanied by high microbial activity forming the base of a food-web that often includes higher organisms like mussels, snails, or shrimp. The primary production is boosted by mixing of chemically reduced hydrothermal vent fluids with ambient seawater, which generates redox disequilibria that serve as energy source for chemolithoautotrophic microbial life. We used geochemical reaction path models to compute the affinities of catabolic (energy-harvesting) and anabolic (biosynthesis) reactions along trajectories of batch mixing between vent fluids and 2 °C seawater. Geochemical data of endmember hydrothermal fluids from 12 different vent fields (Lost City, Rainbow, Logatchev, TAG, EPR 21 °N, Manus Basin, Mariana Arc, etc.) were included in this reconnaissance study of the variability in metabolic energetics in global submarine vent systems. The results show a distinction between ultramafic-hosted and basalt-hosted hydrothermal systems. The highest energy yield for chemolithotrophic catabolism in ultramafic-hosted hydrothermal systems is reached at low temperature and under slightly aerobic to aerobic conditions. The dominant reactions, for example at Rainbow or Lost City, are the oxidation of H2, Fe2+ and methane. At temperatures >60 °C, anaerobic metabolic reactions, e. g., sulphate reduction and methanogenesis, become more profitable. In contrast, basalt-hosted systems, such as TAG and 21 °N EPR uniformly indicate H2S oxidation to be the catabolically dominant reaction over the entire microbial-relevant temperature range. Affinities were calculated for the formation of individual cellular

  12. Stabilization of dissolved trace metals at hydrothermal vent sites: Impact on their marine biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Sander, Sylvia G.; Powell, Zach D.; Koschinsky, Andrea; Kuzmanovski, Stefan; Kleint, Charlotte

    2014-05-01

    Hydrothermal vents have long been neglected as a significant source of several bioactive trace metals as it was assumed that elements such as Fe, Mn, and Cu etc., precipitate in extensor forming poly-metallic sulfide and oxy-hydroxy sediments in the relative vicinity of the emanation site. However, recently this paradigm has been reviewed since the stabilization of dissolved Fe and Cu from hydrothermal vents was observed [1, 2] and increased concentrations of trace metals can be traced from their hydrothermal source thousands of kilometres through the ocean basins [3]. Furthermore several independent modelling attempts have shown that not only a stabilization of dissolved hydrothermal Fe and Cu is possible [4] but also that hydrothermalism must be a significant source of Fe to be able to balance the Fe-biogeochemical cycle [5]. Here we present new data that gives further evidence of the presence of copper stabilising organic and inorganic compounds in samples characterized by hydrothermal input. We can show that there are systematic differences in copper-complexing ligands at different vent sites such as 5°S on the Mid Atlantic Ridge, Brother Volcano on the Kermadec Arc, and some shallow hydrothermal CO2 seeps in the Bay of Plenty, New Zealand and the Mediterranean Sea. Quantitative and qualitative voltammetric data convincingly indicates that inorganic sulphur and organic thiols form the majority of the strong copper-complexing ligand pool in many of these hydrothermal samples. On average, the high temperature vents had a significantly higher copper binding capacity than the diffuse vents due to higher inorganic sulphur species concentrations. References: [1] Sander, S. G., et al. 2007. Organic complexation of copper in deep-sea hydrothermal vent systems. Environmental Chemistry 4: 81-89 [2] Bennett, S. A., et al. 2008. The distribution and stabilisation of dissolved Fe in deep-sea hydrothermal plumes. Earth and Planetary Science Letters 270: 157-167. [3] Wu J

  13. Comparative assessment of five potential sites for hydrothermal-magma systems: summary

    SciTech Connect

    Luth, W.C.; Hardee, H.C.

    1980-11-01

    A comparative assessment of five potential hydrothermal-magma sites for this facet of the Thermal Regimes part of the CSDP has been prepared for the DOE Office of Basic Energy Sciences. The five sites are: The Geysers-Clear Lake, CA, Long Valley, CA, Rio Grande Rift, NM, Roosevelt Hot Springs, UT, and Salton Trough, CA. This site assessment study has drawn together background information (geology, geochemistry, geophysics, and energy transport) on the five sites as a preliminary stage to site selection. Criteria for site selection are that potential sites have identifiable, or likely, hydrothermal systems and associated magma sources, and the important scientific questions can be identified and answered by deep scientific holes. Recommendations were made.

  14. Discovery of Active Hydrothermal Sites Along the Mariana Volcanic Arc, Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Embley, R. W.; Resing, J. A.; Lupton, J. E.; Massoth, G. J.; de Ronde, C. E.; Nakamura, K.; Walker, S. L.

    2003-12-01

    Some 20,000 km of volcanic arcs, roughly one-third the total length of the global midocean ridge (MOR) system, rim the western Pacific Ocean. But compared to 25 years of hydrothermal investigations along MORs, exploration of similar activity on the estimated 600 submarine arc volcanoes is only beginning. In February 2003, as part of the Submarine Ring of Fire project funded by NOAA's Ocean Exploration Program, we made the first systematic survey of hydrothermal activity along the 1270-km-long Mariana intraoceanic volcanic arc, which lies almost entirely within the US EEZ. Prior fieldwork had documented active (but low-temperature) hydrothermal discharge on only three volcanoes: Kasuga 2, Kasuga 3, and Esmeralda Bank. During the cruise, we conducted 70 CTD operations over more than 50 individual volcanoes from 13° N to 23° N, plus a continuous CTD survey along 75 km of the back-arc spreading center (13° 15'N to 13° 41'N) adjacent to the southern end of the arc. We found evidence for active hydrothermal venting at 11 submarine volcanoes with summit (or caldera floor) depths ranging from 50 to 1550 m. Two additional sites were identified on the back-arc spreading center. Ongoing analyses of collected water samples could increase these totals. Our results confirmed continuing hydrothermal activity at Kasuga 2 (but not Kasuga 3) and Esmeralda Bank, in addition to newly discovered sites on nine other volcanoes. Many of these sites produce intense and widely dispersed plumes indicative of vigorous, high-temperature discharge. The volcanoes with active hydrothermal systems are about equally divided between those with and without summit calderas. The addition of the Marianas data greatly improves our view of hydrothermal sources along arcs. The 20,000 km of Pacific arcs can be divided between 6380 km of intraoceanic (i.e., mostly submarine) arcs and 13,880 km of island (i.e., mostly subaerial) arcs. At present, ˜15% of the total length of Pacific arcs has been surveyed

  15. Free-living nematode species (Nematoda) dwelling in hydrothermal sites of the North Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Tchesunov, Alexei V.

    2015-12-01

    Morphological descriptions of seven free-living nematode species from hydrothermal sites of the Mid-Atlantic Ridge are presented. Four of them are new for science: Paracanthonchus olgae sp. n. (Chromadorida, Cyatholaimidae), Prochromadora helenae sp. n. (Chromadorida, Chromadoridae), Prochaetosoma ventriverruca sp. n. (Desmodorida, Draconematidae) and Leptolaimus hydrothermalis sp. n. (Plectida, Leptolaimidae). Two species have been previously recorded in hydrothermal habitats, and one species is recorded for the first time in such an environment. Oncholaimus scanicus (Enoplida, Oncholaimidae) was formerly known from only the type locality in non-hydrothermal shallow milieu of the Norway Sea. O. scanicus is a very abundant species in Menez Gwen, Lucky Strike and Lost City hydrothermal sites, and population of the last locality differs from other two in some morphometric characteristics. Desmodora marci (Desmodorida, Desmodoridae) was previously known from other remote deep-sea hydrothermal localities in south-western and north-eastern Pacific. Halomonhystera vandoverae (Monhysterida, Monhysteridae) was described and repeatedly found in mass in Snake Pit hydrothermal site. The whole hydrothermal nematode assemblages are featured by low diversity in comparison with either shelf or deep-sea non-hydrothermal communities. The nematode species list of the Atlantic hydrothermal vents consists of representatives of common shallow-water genera; the new species are also related to some shelf species. On the average, the hydrothermal species differ from those of slope and abyssal plains of comparable depths by larger sizes, diversity of buccal structures, presence of food content in the gut and ripe eggs in uteri.

  16. Comparison of Five Hydrothermal Vent Fields at the Mid-Atlantic Ridge: Which Parameters Control the Differences in Fluid Geochemistry?

    NASA Astrophysics Data System (ADS)

    Schmidt, K.; Koschinsky, A.; Garbe-Schönberg, D.; Seifert, R.

    2006-12-01

    Five different high-temperature hydrothermal vent sites along the Mid-Atlantic Ridge are investigated within a special priority program funded by the German Research Foundation (SPP 1144). The sites are all located at 3000 m water depth (near the critical point of seawater). Comparing the geochemical signature of the hydrothermal fluids with respect to the individual setting, it is possible to distinguish between the major controlling parameters as they are phase separation in the supercritical region of seawater, temperature, and host rock composition. Three of the vent sites were found at 4°49'S on the MAR in a young post-eruptive basaltic setting. Two of them are characterized by strong phase separation and the highest temperatures measured so far along the MAR (up to 407°C), assuming a very shallow heat source. It is assumed, that this hydrothermal system newly formed after a big eruption event in this region. The other one, although located at a distance of maximum 2 km from the other two, emanates somewhat cooler fluids (up to 349°C), with no indications for boiling and phase separation Despite their spatial proximity and the identical basaltic host rock in which these fields are situated, the vent fields show a clearly different fluid chemistry with depletion of alkali and earth alkali elements and some trace metals in the very hot, phase separated fluids. The Logatchev field at 14°45'N is located in an ultramafic setting with outcropping peridotitic and gabbroic rocks. The chlorinity of the fluids does not clearly indicate phase separation. Compared to the non-phase separated basaltic system at 4°49'S MAR the fluids are characterized by significantly higher concentrations of hydrogen and methane due to the serpentinization reactions, lower silica and lithium concentrations and a depletion of boron. A identical chemical signature characterizes a recently discovered system at 8°18'S, the Nibelungen field. Host rock composition with both mafic and

  17. Martian Magmatic-Driven Hydrothermal Sites: Potential Sources of Energy, Water, and Life

    NASA Technical Reports Server (NTRS)

    Anderson, R. C.; Dohm, J. M.; Baker, V. R.; Ferris, J. C.; Hare, T. M.; Tanaka, K. L.; Klemaszewski, J. E.; Skinner, J. A.; Scott, D. H.

    2000-01-01

    Magmatic-driven processes and impact events dominate the geologic record of Mars. Such recorded geologic activity coupled with significant evidence of past and present-day water/ice, above and below the martian surface, indicate that hydrothermal environments certainly existed in the past and may exist today. The identification of such environments, especially long-lived magmatic-driven hydrothermal environments, provides NASA with significant target sites for future sample return missions, since they (1) could favor the development and sustenance of life, (2) may comprise a large variety of exotic mineral assemblages, and (3) could potentially contain water/ice reservoirs for future Mars-related human activities. If life developed on Mars, the fossil record would presumably be at its greatest concentration and diversity in environments where long-term energy sources and water coexisted such as at sites where long-lived, magmatic-driven hydrothermal activity occurred. These assertions are supported by terrestrial analogs. Small, single-celled creatures (prokaryotes) are vitally important in the evolution of the Earth; these prokaryotes are environmentally tough and tolerant of environmental extremes of pH, temperature, salinity, and anoxic conditions found around hydrothermal vents. In addition, there is a great ability for bacteria to survive long periods of geologic time in extreme conditions, including high temperature hydrogen sulfide and sulfur erupted from Mount St. Helens volcano. Our team of investigators is conducting a geological investigation using multiple mission-derived datasets (e.g., existing geologic map data, MOC imagery, MOLA, TES image data, geophysical data, etc.) to identify prime target sites of hydrothermal activity for future hydrological, mineralogical, and biological investigations. The identification of these sites will enhance the probability of success for future missions to Mars.

  18. Hydrothermal plumes over the Carlsberg Ridge, Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ray, Durbar; Kamesh Raju, K. A.; Baker, Edward T.; Srinivas Rao, A.; Mudholkar, Abhay V.; Lupton, John E.; Surya Prakash, L.; Gawas, Rekha B.; Vijaya Kumar, T.

    2012-01-01

    Indian Ocean ridges north of the Rodriguez Triple Junction remain poorly explored for seafloor hydrothermal activity, with only two active sites confirmed north of 25°S. We conducted water column surveys and sampling in 2007 and 2009 to search for hydrothermal plumes over a segment of the Carlsberg Ridge. Here we report evidence for two separate vent fields, one near 3°42'N, 63°40'E and another near 3°41.5'N, 63°50'E, on a segment that is apparently sparsely magmatic. Both sites appear to be located on off-axis highs at the top of the southern axial valley wall, at depths of ˜3600 m or shallower (˜1000 m above the valley floor). At the 63°40'E site, plume sampling found local maxima in light scattering, temperature anomaly, oxidation-reduction potential (ORP), dissolved Mn, and3He. No water samples are available from the 63°50'E site, but it showed robust light-scattering and ORP anomalies at multiple depths, implying multiple sources. ORP anomalies are very short-lived, so the strong signals at both sites suggest that fluid sources lie within a few kilometers or less from the plume sampling locations. Although ultramafic rocks have been recovered near these sites, the light-scattering and dissolved Mn anomalies imply that the plumes do not arise from a system driven solely by exothermic serpentinization (e.g., Lost City). Instead, the source fluids may be a product of both ultramafic and basaltic/gabbroic fluid-rock interaction, similar to the Rainbow and Logatchev fields on the Mid-Atlantic Ridge.

  19. Near-bottom magnetic surveys around hydrothermal sites in the southern Mariana Trough

    NASA Astrophysics Data System (ADS)

    Nogi, Y.; Mochizuki, N.; Okino, K.; Asada, M.

    2011-12-01

    Near-bottom magnetic survey is an effective method to reveal detailed magnetic anomaly features of seafloor. The measurements of three-components of the geomagnetic field by using AUV "URASHIMA" were conducted during the YK-09-08 cruise in the southern Mariana Trough in order to detect signals of hydrothermally altered rocks. During the cruise, vector geomagnetic field are successfully obtained along the all dive tracks with the information of the vehicle's attitude. Total intensities of geomagnetic field by the overhauser magnetometer were also conducted, but the data are only collected along almost E-W oriented observation lines due to the sensitivity of the sensor. The distribution of crustal magnetization are estimated using downward component of magnetic anomalies by the inversion method. The distribution of low crustal magnetization are almost coincide with the area around hydrothermal vent sites from on ridge to off ridge area, and most likely indicate signs of hydrothermally altered rocks. The distribution of low crustal magnetization on ridge are almost parallel to the the strike of ridge axis implying tectonic control of hydrothermal vent sites.

  20. First hydrothermal discoveries on the Australian-Antarctic Ridge: Discharge sites, plume chemistry, and vent organisms

    NASA Astrophysics Data System (ADS)

    Hahm, Doshik; Baker, Edward T.; Siek Rhee, Tae; Won, Yong-Jin; Resing, Joseph A.; Lupton, John E.; Lee, Won-Kyung; Kim, Minjeong; Park, Sung-Hyun

    2015-09-01

    The Australian-Antarctic Ridge (AAR) is one of the largest unexplored regions of the global mid-ocean ridge system. Here, we report a multiyear effort to locate and characterize hydrothermal activity on two first-order segments of the AAR: KR1 and KR2. To locate vent sites on each segment, we used profiles collected by Miniature Autonomous Plume Recorders on rock corers during R/V Araon cruises in March and December of 2011. Optical and oxidation-reduction-potential anomalies indicate multiple active sites on both segments. Seven profiles on KR2 found 3 sites, each separated by ˜25 km. Forty profiles on KR1 identified 17 sites, some within a few kilometer of each other. The spatial density of hydrothermal activity along KR1 and KR2 (plume incidence of 0.34) is consistent with the global trend for a spreading rate of ˜70 mm/yr. The densest area of hydrothermal activity, named "Mujin," occurred along the 20 km-long inflated section near the segment center of KR1. Continuous plume surveys conducted in January-February of 2013 on R/V Araon found CH4/3He (1 - 15 × 106) and CH4/Mn (0.01-0.5) ratios in the plume samples, consistent with a basaltic-hosted system and typical of ridges with intermediate spreading rates. Additionally, some of the plume samples exhibited slightly higher ratios of H2/3He and Fe/Mn than others, suggesting that those plumes are supported by a younger hydrothermal system that may have experienced a recent eruption. The Mujin-field was populated by Kiwa crabs and seven-armed Paulasterias starfish previously recorded on the East Scotia Ridge, raising the possibility of circum-Antarctic biogeographic connections of vent fauna.

  1. Dike control of hydrothermal circulation in the Tertiary Icelandic crust and implications for cooling of the seafloor

    NASA Astrophysics Data System (ADS)

    Pałgan, Dominik; Devey, Colin W.; Yeo, Isobel A.

    2016-04-01

    Hydrothermal activity along the Mid-Atlantic Ridge is predominantly high-temperature venting controlled by volcano-tectonic processes confined to the ridge axis and neotectonic zone, which extends ~ 20 km on each side of the axis (e.g. TAG or Logatchev 1). These vents cannot, however, account for all the heat which needs to be removed to cool the plate and a significant amount of heat is probably removed in the off-axis regions as well. These regions have previously not been systematically surveyed for hydrothermal activity due to a lack of predictive models for its nature, location or controlling structures. Here we use hot springs in the Tertiary Westfjords of Iceland as onshore analogs for hydrothermal activity along the off-axis Mid-Atlantic Ridge to better understand tectonic and volcanological controls on their occurrence, as well as the processes which support hydrothermal circulation. Our results show that even crust ≥ 10 Ma has abundant low-temperature hydrothermal activity. We show that 66% of hot springs investigated, and 100% of those for which a detailed geological setting could be determined, are associated with basaltic dikes cross-cutting the sub-horizontal lava sequence. This is in strong contrast to on-axis springs, which are known (both from underwater and on land) to be predominantly associated with faults. Absence of earthquakes in Westfjords suggests that the faults there are no longer active and possibly sealed by secondary minerals, suppressing fluid circulation. In such a situation, the jointed and fractures dike margins may provide the major pathways for fluid circulation. Extrapolating this idea to the off-axis regions of the Reykjanes Ridge, we suggest, based on bathymetric maps, potential sites for future exploration for off-axis hydrothermal systems.

  2. Discovery of New Hydrothermal Venting Sites in the Lau Basin, Tonga Back Arc

    NASA Astrophysics Data System (ADS)

    Crowhurst, P. V.; Arculus, R. J.; Massoth, G. J.; Baptista, L.; Stevenson, I.; Angus, R.; Baker, E. T.; Walker, S. L.; Nakamura, K.

    2009-12-01

    Between 22 April and 25 June 2009, a systematic search for hydrothermal venting along 1340 km of back-arc features was conducted throughout the Lau Basin aboard the CSIRO owned RV Southern Surveyor. The selection of survey areas was based on bathymetry, sidescan and water column anomaly datasets collected during previous marine science research and commercial exploration voyages. During 54 operational days, 76 CTD tows were completed using real-time plume mapping protocols, augmented with mini autonomous plume recorders, to discern anomalies in light scattering, and oxidation-reduction potential with water samples collected within the peak anomalies. Coincident with CTD towing at an average speed of 1.1 knots high resolution EM300 bathymetry and backscatter data was collected which significantly enhanced geological interpretation of possible source sites for follow up cross tows. 32 venting sites were detected, 24 of which are believed to be new discoveries. 13 dredge operations were conducted on 7 of these sites. Sulfides were recovered from 2 sites, one being a new discovery on the NE Lau spreading centre, ~14 km north of the commercial discovery by Teck and ~7km north of the eruption site discovery during a RV Thompson NOAA survey, both during 2008. The new venting field discoveries at North Mata, northern extent of the CLSC and far southern Valu Fa ridge are beyond any previously known areas of hydrothermal activity and further enhances the reputation of the Lau Basin as one of the most productive back arc regions for hydrothermally active spreading centers. A significant number of filter residue samples collected from the vent sites yielded greater than background values for metals including Cu and Zn, which is interpreted to imply they were sourced from active seafloor massive sulfide systems rather than volcanic activity.

  3. Comparative assessment of five potential sites for magma: hydrothermal systems - geophysics

    SciTech Connect

    Kasameyer, P.

    1980-09-02

    As part of a comparative assessment for the Continental Scientific Drilling Program, geophysical data were used, to characterize and evaluate potential magma-hydrothermal targets at five drill sites in the western United States. The sites include Roosevelt Hot Springs, Utah, the Rio Grande Rift, New Mexico, and The Geysers-Clear Lake, Long Valley, and Salton Trough areas, California. This summary discusses the size, depth, temperature, and setting of each potential target, as well as relvant scientific questions about their natures and the certainty of their existence.

  4. Comparative assessment of five potential sites for hydrothermal-magma systems: energy transport

    SciTech Connect

    Hardee, H.C.

    1980-09-01

    A comparative assessment of five sites is being prepared as part of a Continental Scientific Drilling Program (CSDP) review of thermal regimes for the purpose of scoping areas for future research and drilling activities. This background report: discusses the various energy transport processes likely to be encountered in a hydrothermal-magma system, reviews related literature, discusses research and field data needs, and reviews the sites from an energy transport viewpoint. At least three major zones exist in the magma-hydrothermal transport system: the magma zone, the hydrothermal zone, and the transition zone between the two. Major energy transport questions relate to the nature and existence of these zones and their evolution with time. Additional energy transport questions are concerned with the possible existence of critical state and super-critical state permeable convection in deep geothermal systems. A review of thermal transport models emphasizes the fact that present transport models and computational techniques far outweigh the scarcity and quality of deep field data.

  5. Diffuse versus discrete venting at the Tour Eiffel vent site, Lucky Strike hydrothermal field

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E. L.; Escartin, J.; Gracias, N.; Olive, J. L.; Barreyre, T.; Davaille, A. B.; Cannat, M.

    2010-12-01

    Two styles of fluid flow at the seafloor are widely recognized: (1) localized outflows of high temperature (>300°C) fluids, often black or grey color in color (“black smokers”) and (2) diffuse, lower temperature (<100°C), fluids typically transparent and which escape through fractures, porous rock, and sediment. The partitioning of heat flux between these two types of hydrothermal venting is debated and estimates of the proportion of heat carried by diffuse flow at ridge axes range from 20% to 90% of the total axial heat flux. Here, we attempt to improve estimates of this partitioning by carefully characterizing the heat fluxes carried by diffuse and discrete flows at a single vent site, Tour Eiffel in the Lucky Strike hydrothermal field along the Mid-Atlantic Ridge. Fluid temperature and video data were acquired during the recent Bathyluck’09 cruise to the Lucky Strike hydrothermal field (September, 2009) by Victor aboard “Pourquoi Pas?” (IFREMER, France). Temperature measurements were made of fluid exiting discrete vents, of diffuse effluents immediately above the seafloor, and of vertical temperature gradients within discrete hydrothermal plumes. Video data allow us to calculate the fluid velocity field associated with these outflows: for diffuse fluids, Diffuse Flow Velocimetry tracks the displacement of refractive index anomalies through time; for individual hydrothermal plumes, Particle Image Velocimetry tracks eddies by cross-correlation of pixels intensities between subsequent images. Diffuse fluids exhibit temperatures of 8-60°C and fluid velocities of ~1-10 cm s-1. Discrete outflows at 204-300°C have velocities of ~1-2 m s-1. Combined fluid flow velocities, temperature measurements, and full image mosaics of the actively venting areas are used to estimate heat flux of both individual discrete vents and diffuse outflow. The total integrated heat flux and the partitioning between diffuse and discrete venting at Tour Eiffel, and its

  6. Liquid Carbon Dioxide Venting at the Champagne Hydrothermal Site, NW Eifuku Volcano, Mariana Arc

    NASA Astrophysics Data System (ADS)

    Lupton, J.; Lilley, M.; Butterfield, D.; Evans, L.; Embley, R.; Olson, E.; Proskurowski, G.; Resing, J.; Roe, K.; Greene, R.; Lebon, G.

    2004-12-01

    In March/April 2004, submersible dives with the remotely-operated vehicle ROPOS discovered an unusual CO2-rich hydrothermal system near the summit of NW Eifuku, a submarine volcano located at 21.49° N, 144.04° E in the northern Mariana Arc. Although several sites of hydrothermal discharge were located on NW Eifuku, the most intense venting was found at 1600-m depth at the Champagne site, slightly west of the volcano summit. The Champagne site was found to be discharging two distinct fluids into the ocean: a) several small white chimneys were emitting milky 103° C gas-rich hydrothermal fluid with at least millimolar levels of H2S and b) cold (< 4° C) droplets coated with a milky skin were rising slowly from the sediment. These droplets were later determined to consist mainly of liquid CO2, with H2S as a probable secondary component. The droplets were sticky, and did not tend to coalesce into larger droplets, even though they adhered to the ROV like clumps of grapes. The film coating the droplets was assumed to be CO2 hydrate (or clathrate) which is known to form whenever liquid CO2 contacts water under these P,T conditions. Samples of the 103° C hydrothermal fluids were collected in special gas-tight titanium sampling bottles that were able to withstand the high internal pressures created by the dissolved gases. The Champagne hydrothermal fluids contained a surprising 2.3 moles/kg of CO2, an order of magnitude higher than any CO2 values previously reported for submarine hydrothermal fluids. The overall gas composition was 87% CO2, < 0.1% CH4, < 2 ppm H2, 0.012 mM/kg 4He, with the remaining 13% (322 mM/kg) assumed to be sulfur gases (H2S, SO2, etc.). (Additional analyses planned will confirm the speciation of this sulfur gas component). The helium had R/RA = 7.3, typical of subduction zone systems (R = 3He/4He and RA = Rair). Isotopic analysis of the CO2 yielded δ 13C = -1.75 ‰ , much heavier than the -6.0 ‰ typical for carbon in MOR vent fluids. The C/3He

  7. Modeling the hydrothermal circulation and the hydrogen production at the Rainbow site with Cast3M

    NASA Astrophysics Data System (ADS)

    Perez, F.; Mügler, C.; Charlou, J.; Jean-baptiste, P.

    2012-12-01

    On the Mid-Atlantic Ridge, the Rainbow venting site is described as an ultramafic-hosted active hydrothermal site and releases high fluxes of methane and hydrogen [1, 2]. This behavior has first been interpreted as the result of serpentinization processes. But geochemical reactions involving olivine and plagioclase assemblages, and leading to chlorite, tremolite, talc and magnetite assemblages, could contribute to the observed characteristics of the exiting fluid [2]. The predominance of one of these geochemical reactions or their coexistence strongly depend on the hydrothermal fluid circulation. We developed and validated a 2D/3D numerical model using a Finite Volume method to simulate heat driven fluid flows in the framework of the Cast3M code [3, 4]. We also developed a numerical model for hydrogen production and transport that is based on experimental studies of the serpentinization processes [5-6]. This geochemical model takes into account the exothermic and water-consuming behavior of the serpentinization reaction and it can be coupled to our thermo-hydrogeological model. Our simulations provide temperatures, mass fluxes and venting surface areas very close to those estimated in-situ [7]. We showed that a single-path model [8] was necessary to simulate high values such as the in-situ measured temperatures and estimated water mass fluxes of the Rainbow site [7]. This single-path model will be used to model the production and transport of hydrogen at the Rainbow hydrothermal site. References [1]Charlou et al. (2010) AGU Monograph series. [2]Seyfried et al. (2011) Geochim. Cosmochim. Acta 75, 1574-1593. [3]http://www-cast3m.cea.fr. [4]Martin & Fyfe (1970) Chem. Geol. 6, 185-202. [5] Marcaillou et al. (2011) Earth and Planet. Sci. Lett. 303, 281-290. [6]Malvoisin et al. (2012) JGR, 117, B01104. [7]Perez et al. (2012) submited to Computational Geosciences. [8]Lowell & Germanovich (2004) AGU, Washington DC, USA.

  8. Quantifying diffuse and discrete venting at the Tour Eiffel vent site, Lucky Strike hydrothermal field

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; EscartíN, Javier; Gracias, Nuno; Olive, Jean-Arthur; Barreyre, Thibaut; Davaille, Anne; Cannat, Mathilde; Garcia, Rafael

    2012-04-01

    The relative heat carried by diffuse versus discrete venting of hydrothermal fluids at mid-ocean ridges is poorly constrained and likely varies among vent sites. Estimates of the proportion of heat carried by diffuse flow range from 0% to 100% of the total axial heat flux. Here, we present an approach that integrates imagery, video, and temperature measurements to accurately estimate this partitioning at a single vent site, Tour Eiffel in the Lucky Strike hydrothermal field along the Mid-Atlantic Ridge. Fluid temperatures, photographic mosaics of the vent site, and video sequences of fluid flow were acquired during the Bathyluck'09 cruise (Fall, 2009) and the Momarsat'10 cruise (Summer, 2010) to the Lucky Strike hydrothermal field by the ROV Victor6000 aboard the French research vessel the "Pourquoi Pas"? (IFREMER, France). We use two optical methods to calculate the velocities of imaged hydrothermal fluids: (1) for diffuse venting, Diffuse Flow Velocimetry tracks the displacement of refractive index anomalies through time, and (2) for discrete jets, Particle Image Velocimetry tracks eddies by cross-correlation of pixel intensities between subsequent images. To circumvent video blurring associated with rapid velocities at vent orifices, exit velocities at discrete vents are calculated from the best fit of the observed velocity field to a model of a steady state turbulent plume where we vary the model vent radius and fluid exit velocity. Our results yield vertical velocities of diffuse effluent between 0.9 cm s-1 and 11.1 cm s-1 for fluid temperatures between 3°C and 33.5°C above that of ambient seawater, and exit velocities of discrete jets between 22 cm s-1 and 119 cm s-1 for fluid temperatures between 200°C and 301°C above ambient seawater. Using the calculated fluid velocities, temperature measurements, and photo mosaics of the actively venting areas, we calculate a heat flux due to diffuse venting from thin fractures of 3.15 ± 2.22 MW, discrete venting of

  9. Expression patterns of mRNAs for methanotrophy and thiotrophy in symbionts of the hydrothermal vent mussel Bathymodiolus puteoserpentis

    PubMed Central

    Wendeberg, Annelie; Zielinski, Frank U; Borowski, Christian; Dubilier, Nicole

    2012-01-01

    The hydrothermal vent mussel Bathymodiolus puteoserpentis (Mytilidae) from the Mid-Atlantic Ridge hosts symbiotic sulfur- and methane-oxidizing bacteria in its gills. In this study, we investigated the activity and distribution of these two symbionts in juvenile mussels from the Logatchev hydrothermal vent field (14°45′N Mid-Atlantic Ridge). Expression patterns of two key genes for chemosynthesis were examined: pmoA (encoding subunit A of the particulate methane monooxygenase) as an indicator for methanotrophy, and aprA (encoding the subunit A of the dissimilatory adenosine-5′-phosphosulfate reductase) as an indicator for thiotrophy. Using simultaneous fluorescence in situ hybridization (FISH) of rRNA and mRNA we observed highest mRNA FISH signals toward the ciliated epithelium where seawater enters the gills. The levels of mRNA expression differed between individual specimens collected in a single grab from the same sampling site, whereas no obvious differences in symbiont abundance or distribution were observed. We propose that the symbionts respond to the steep temporal and spatial gradients in methane, reduced sulfur compounds and oxygen by modifying gene transcription, whereas changes in symbiont abundance and distribution take much longer than regulation of mRNA expression and may only occur in response to long-term changes in vent fluid geochemistry. PMID:21734728

  10. Origin of magnetic highs at ultramafic hosted hydrothermal systems: Insights from the Yokoniwa site of Central Indian Ridge

    NASA Astrophysics Data System (ADS)

    Fujii, Masakazu; Okino, Kyoko; Sato, Taichi; Sato, Hiroshi; Nakamura, Kentaro

    2016-05-01

    High-resolution vector magnetic measurements were performed on an inactive ultramafic-hosted hydrothermal vent field, called Yokoniwa Hydrothermal Field (YHF), using a deep-sea manned submersible Shinkai6500 and an autonomous underwater vehicle r2D4. The YHF has developed at a non-transform offset massif of the Central Indian Ridge. Dead chimneys were widely observed around the YHF along with a very weak venting of low-temperature fluids so that hydrothermal activity of the YHF was almost finished. The distribution of crustal magnetization from the magnetic anomaly revealed that the YHF is associated with enhanced magnetization, as seen at the ultramafic-hosted Rainbow and Ashadze-1 hydrothermal sites of the Mid-Atlantic Ridge. The results of rock magnetic analysis on seafloor rock samples (including basalt, dolerite, gabbro, serpentinized peridotite, and hydrothermal sulfide) showed that only highly serpentinized peridotite carries high magnetic susceptibility and that the natural remanent magnetization intensity can explain the high magnetization of Yokoniwa. These observations reflect abundant and strongly magnetized magnetite grains within the highly serpentinized peridotite. Comparisons with the Rainbow and Ashadze-1 suggest that in ultramafic-hosted hydrothermal systems, strongly magnetized magnetite and pyrrhotite form during the progression of hydrothermal alteration of peridotite. After the completion of serpentinization and production of hydrogen, pyrrhotites convert into pyrite or nonmagnetic iron sulfides, which considerably reduces their levels of magnetization. Our results revealed origins of the magnetic high and the development of subsurface chemical processes in ultramafic-hosted hydrothermal systems. Furthermore, the results highlight the use of near-seafloor magnetic field measurements as a powerful tool for detecting and characterizing seafloor hydrothermal systems.

  11. Lithosphere-biosphere interaction at a shallow-sea hydrothermal vent site; Hot Lake, Panarea, Italy

    NASA Astrophysics Data System (ADS)

    Huang, Chia-I.; Amann, Rudolf; Amend, Jan P.; Bach, Wolfgang; Brunner, Benjamin; Meyerdierks, Anke; Price, Roy E.; Schubotz, Florence; Summons, Roger; Wenzhöfer, Frank

    2010-05-01

    Deep-Sea hydrothermal systems are unique habitats for microbial life with primary production based on chemosynthesis and are considered to be windows to the subsurface biosphere. It is often overlooked, however, that their far more accessible shallow-sea counterparts are also valuable targets to study the effects of hydrothermal activity on geology, seawater chemistry and finally, on microbial life. Such an area of shallow marine hydrothermal venting is observed approximately 2.5 km east of Panarea Island (Sicily, Italy). This system is characterized by fluid temperatures of up to 135° C, gas emissions dominated by CO2 and precipitation of elemental sulfur on the seafloor. In an interdisciplinary project to investigate the influence of geofuels on marine microbiota, sediment cores and pore fluids were sampled for geological and geochemical analyses. An attempt was made to link these geochemical data with a characterization of the microbial community. One of the investigated sites (Lago Caldo, Hot Lake) is an oval-shaped (~10 by 6 meters) shallow (~2.5 m deep) depression covered by elemental sulfur. The sediments in this depression are strongly affected by hydrothermal activity: the pH of pore fluids is in a range between 5 and 6; the salinity is approximately two times higher than seawater. In situ temperatures of 36° C and 74° C (10 cm sediment depth) at two different locations within Hot Lake indicate variability in hydrothermal flux. The sediment surface layer is anoxic, and with increasing depth from the sediment-water interface, sulfate concentrations decrease from ~30 mM to less than 10 mM, whereas sulfide concentrations increase from less than 50 μm to ~1000 μm at 25 cm sediment depth, thus suggesting a higher potential for energy gain based on sulfur disequilibrium. As indicated by the variability in the sediment temperatures at 10 cm, fluid fluxes and mixing with seawater is not found to be uniform at Hot Lake. This is reflected in variability of the

  12. Deep-Sea Magnetics on Active and Fossil Hydrothermal Sites: a Tool to Detect and Characterize Submarine Ore Deposits

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Szitkar, F.; Fouquet, Y.; Choi, Y.

    2011-12-01

    Since the first discoveries of hydrothermal sites at mid-ocean ridges in the 70s, international efforts in the deep seafloor exploration have unravelled a wide variety of hydrothermal sites in terms of geological settings, physical parameters, and biological communities as well. Such efforts, coordinated in the InterRidge program since 1992, are becoming even more important when the increasing need in metals for developing economies makes the exploitation of metal sulfides accumulated at deep-sea hydrothermal sites a realistic target. The usual method to find hydrothermal sites is to detect the associated chemical plumes enriched in manganese, methane, hydrogen, helium 3, in the water column. How efficient it has been proven, such a method is limited to the search for active hydrothermal vents. Active vents, however, are not the best places for mining the seafloor, because (1) they host massive sulfides deposits in the making and may not represent the largest accumulation; (2) they are still very hot and would rapidly damage the mining tools; and, last but not the least, (3) they host fragile and precious ecosystem that could be dramatically affected by mining operations. Methods to find fossil hydrothermal sites (i.e. colder and devoid of specific ecosystems) include systematic rock sampling - a very tedious endeavour - and high resolution, near seafloor geophysical surveys. Existing magnetic surveys on basalt-hosted, peridotite-hosted and sediment-hosted sites revealed different types of signatures, which reflect the magnetizations of the host rock and the ore deposit, among others. Basalt-hosted sites exhibit negative magnetic anomalies, i.e. a deficit of magnetization, due to thermal demagnetization and hydrothermal alteration of the highly magnetic basalt, whereas both peridotite-hosted and sediment-hosted sites show positive anomalies, i.e. an excess of magnetization, clearly associated with the ore deposit. Results from recent cruises Serpentine (R

  13. Tidal bottom current modulation of chemical environment in the Suiyo hydrothermal site in the Izu-Ogasawara (Bonin) Arc.

    NASA Astrophysics Data System (ADS)

    Nakamura, K.

    2002-12-01

    Intense seafloor observatory studies were done at the Suiyo hydrothermal site in the summer of 2001 and 2002. Deployed instruments on the seafloor were CTD (Idronaut, Ocean Seven 316), Digiquartz precision pressure sensor and its recorder, 3-D acoustic current meters (NOBSKA, MAVS3), high temperature and redox recorders at the vents, in-situ laser particle analyzer (Sequoia Scientific, LISST-Deep), methane sensor (CAPSUM METS) with its data logger, etc. The Suiyo Seamount hydrothermal site is located in the summit caldera of Izu-Ogasawara (Bonin) Arc (1380 m deep, 28.572 N, 140.643 E). The tide is mixed type dominant with semi-diurnal component. There is no tidal components in temperature and redox records neither at high temperature vents (300 deg C) nor at low temperature vents (less than 200 deg C). Whereas the temperature, redox, methane concentration in the seawater, particle characters measured just above the seafloor had strong semi-diurnal components. The methane concentration varies from several micro mol/litter to several tens of micro mol/litter associated with 200 mV redox change in the central part of the hydrothermal site. Semi-diurnal strong bottom current over 40 cm/sec appeared several hours after high tides introduced entrainment of ambient waters in the marginal part of hydrothermal site and accelerated mixing of vent water with bottom water in the central part of the hydrothermal site. This research was funded by the "Archaean Park" Project (International research project on interaction between sub-vent biosphere and geo environment funded by Special Coordination Fund of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The R/V Natsushima cruise with the sub "Shinkai 2000" was a part of the Deep Sea Research project of the Japan Marine Science and Technology Center (JAMSTEC).

  14. Phylogenetic diversity of methanogenic, sulfate-reducing and methanotrophic prokaryotes from deep-sea hydrothermal vents and cold seeps

    NASA Astrophysics Data System (ADS)

    Reed, Andrew J.; Dorn, Ruth; Van Dover, Cindy L.; Lutz, Richard A.; Vetriani, Costantino

    2009-09-01

    Microbial communities of methanogenic, sulfate-reducing and methanotrophic prokaryotes from deep-sea environments were investigated by molecular phylogenetic analysis of the deduced amino acid sequences of the genes encoding for the methyl coenzyme M reductase ( mcrA), dissimilatory sulfite reductase ( dsrAB) and particulate methane monoxygenase ( pmoA), respectively. Clone libraries of PCR amplified genes were constructed using DNA extracted from deep-sea vent chimneys (Rainbow and Logatchev hydrothermal vent fields, Mid-Atlantic Ridge, Atlantic Ocean; 9°N East Pacific Rise, Pacific Ocean) and from vertically subsampled sediment cores from cold-seep areas (Blake Ridge, western Atlantic Ocean; Florida Escarpment, Gulf of Mexico). Recombinant clones were screened by RFLP and representative dsrAB, mcrA and pmoA genes were sequenced. The dsrAB sequences grouped primarily within the orders Desulfobacterales, Syntrophobacterales and the Gram-positive order Clostridales. Cold-seep mcrA sequences were distributed among the ANME-2c, -2d and -2e groups, which were previously shown to be associated with the anaerobic oxidation of methane. This study also reports the first mcrA sequences from a high-temperature, black smoker chimney (Logatchev) to group within the ANME-2e subgroup. The majority of the remaining hydrothermal vent mcrA sequences were primarily related to thermophilic members of the anaerobic, methanogenic order Methanococcales. A shift in the dominant ANME-2 group with depth in the sediment for both Florida Escarpment and Blake Ridge mcrA libraries was detected. ANME-2d related clones were detected in the top zones of both cores, with the frequency of ANME-2e related clones increasing with depth. All pmoA sequences retrieved from the cold-seep sites were found to be related to Type I methanotrophic members of the γ-proteobacteria, and were primarily distributed among three major clusters of sequences. No Type II pmoA sequences related to methanotrophic

  15. Microbial control of silver mineralization at a sea-floor hydrothermal site on the northern Gorda Ridge

    USGS Publications Warehouse

    Zierenberg, R.A.; Schiffman, P.

    1990-01-01

    THE Sea Cliff hydrothermal field, on the northern Gorda Ridge, contains mounds and chimneys of hydrothermally precipitated sulphide and sulphate minerals typical of sea-floor hydrothermal vent sites1. In addition, large areas of the sea floor are covered by subhorizontal hydrothermal crusts. Samples of the crust recovered by submersible are composed of intensely altered fragments of basalt and basaltic hyaloclastite cemented by amorphous silica and chalcedony with less abundant barite, and minor amounts of base-metal sulphide minerals2. Some surfaces of the crust were formerly colonized by bacterial mats, which are locally preserved by replacement and overgrowth of the bacterial filaments by metal sulphide minerals and amorphous silica. The bacterial filaments are selectively replaced by prousite (Ag3AsS3), pearceite3 (Ag14.7-XCu1.3+xAs2S11), chalcopyrite (CuFeS2) and rarely by galena (PbS). Our observations suggest that bacterially mediated processes selectively precipitate silver, arsenic and copper, and that biological processes may contribute to precious-metal enrichment in some sea-floor hydrothermal base-metal sulphide deposits.

  16. Hydrothermal Activity on the Mid-Cayman Rise: ROV Jason sampling and site characterization at the Von Damm and Piccard hydrothermal fields

    NASA Astrophysics Data System (ADS)

    German, C. R.

    2012-12-01

    In January 2012 our multi-national and multi-disciplinary team conducted a series of 10 ROV Jason dives to conduct first detailed and systematic sampling of the Mid Cayman Rise hydrothermal systems at the Von Damm and Piccard hydrothermal fields. At Von Damm, hydrothermal venting is focused at and around a large conical structure that is approximately 120 m in diameter and rises at least 80m from the surrounding, largely sedimented seafloor. Clear fluids emitted from multiple sites around the flanks of the mound fall in the temperature range 110-130°C and fall on a common mixing line with hotter (>200°C) clear fluids emitted from an 8m tall spire at the summit which show clear evidence of ultramafic influence. Outcrop close to the vent-site is rare and the cone itself appear to consist of clay minerals derived from highly altered host rock. The dominant fauna at the summit of Von Damm are a new species of chemosynthetic shrimp but elsewhere the site also hosts two distinct species of chemosynthetic tube worm as well as at least one species of gastropod. The adjacent Piccard site, at ~5000m depth comprises 7 distinct sulfide mounds, 3 of which are currently active: Beebe Vents, Beebe Woods and Beebe Sea. Beebe Vents consists of 5 vigorous black smoker chimneys with maximum temperatures in the range 400-403°C while at Beebe Woods a more highly colonized thicket of up to 8m tall chimneys includes predominantly beehive diffusers with rare black smokers emitting fluids up to 353°C. Beebe Sea a diffuse site emitting fluids at 38°C Tmax, is the largest of the currently active mounds and immediately abuts a tall (8m) rift that strikes NE-SW bisecting the host Axial Volcanic Ridge. The fauna at Piccard are less diverse than at Von Damm and, predominantly, comprise the same species of MCR shrimp, a distinct gastropod species and abundant anemones.

  17. Time-variation of hydrothermal discharge at selected sites in the Western United States: Implications for monitoring

    USGS Publications Warehouse

    Ingebritsen, S.E.; Galloway, D.L.; Colvard, E.M.; Sorey, M.L.; Mariner, R.H.

    2001-01-01

    We compiled time series of hydrothermal discharge consisting of 3593 chloride- or heat-flux measurements from 24 sites in the Yellowstone region, the northern Oregon Cascades, Lassen Volcanic National Park and vicinity, and Long Valley, California. At all of these sites the hydrothermal phenomena are believed to be as yet unaffected by human activity, though much of the data collection was driven by mandates to collect environmental-baseline data in acticipation of geothermal development. The time series average 19 years in length and some of the Yellowstone sites have been monitored intermittently for over 30 years. Many sites show strong seasonality but few show clear long-term trends, and at most sites statistically significant decadal-scale trends are absent. Thus, the data provide robust estimates of advective heat flow ranging from ~130 MW in the north-central Oregon Cascades to ~6100 MW in the Yellowstone region, and also document Yellowstone hydrothermal chloride and arsenic fluxes of 1740 and 15-20 g/s, respectively. The discharge time series show little sensitivity to regional tectonic events such as earthquakes or inflation/deflation cycles. Most long-term monitoring to date has focused on high-chloride springs and low-temperature fumaroles. The relative stability of these features suggests that discharge measurements done as part of volcano-monitoring programs should focus instead on high-temperature fumaroles, which may be more immediately linked to the magmatic heat source. ?? 2001 Elsevier Science B.V. All rights reserved.

  18. Pb isotopes in sulfides from mid-ocean ridge hydrothermal sites

    SciTech Connect

    LeHuray, A.P.; Church, S.E.; Koski, R.A.; Bouse, R.M.

    1988-04-01

    The authors report Pb isotope ratios of sulfides deposited at seven recently active mid-ocean ridge (MOR) hydrothermal vents. Sulfides from three sediment-starved sites on the Juan de Fuca Ridge contain Pb with isotope ratios identical to their local basaltic sources. Lead in two deposits from the sediment-covered Escanaba Trough, Gorda Ridge, is derived from the sediments and does not appear to contain any basaltic component. There is a range of isotope ratios in a Guaymas Basin deposit, consistent with a mixture of sediment and MOR basalt Pb. Lead in a Galapagos deposit differs slightly from known Galapagos basalt Pb isotope values. The faithful record of Pb isotope signatures of local sources in MOR sulfides indicates that isotope ratios from ancient analogues ca be used as accurate reflections of ancient oceanic crustal values in ophiolite-hosted deposits and continental crustal averages in sediment-hosted deposits. The preservation of primary ophiolitic or continental crustal Pb isotope signatures in ancient MOR sulfides provides a powerful tool for investigation of crustal evolution and for fingerprinting ancient terranes.

  19. Formation of Intermediate Carbon Phases in Hydrothermal Abiotic Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Fu, Q.; Foustoukos, D. I.; Seyfried, W. E.

    2005-12-01

    With high dissolved concentrations of methane and other hydrocarbon species revealed at the Rainbow and Logatchev vent systems on the Mid-Atlantic Ridge, it is essential to better understand reaction pathways of abiotic organic synthesis in hydrothermal systems. Thus, we performed a hydrothermal carbon reduction experiment with 13C labeled carbon source at temperature and pressure conditions that approximate those inferred for ultramafic-hosted hydrothermal systems. Pentlandite, a common alteration mineral phase in subseafloor reaction zones, acted as a potential catalyst. Surface analysis techniques (XPS and ToF-SIMS) were used to characterize intermediate carbon species within this process. Time series dissolved H2 and H2S concentrations indicated thermodynamic equilibrium. Dissolved H2 and H2S concentrations of 13 and 2 mmol/kg, respectively, are approximately equivalent to measured values in Rainbow and Logatchev hydrothermal systems. Isotopically pure 13C methane and other alkane species (C2H6 and C3H8) were observed throughout the experiment, and attained steady state conditions. XPS analysis on mineral product surface indicated carbon enrichment on mineral surface following reaction. The majority of surface carbon involves species containing C-C or C-H bonds, such as alkyl or methylene groups. Alcohol and carboxyl groups in fewer amounts were also observed. ToF-SIMS analysis, which can offer isotope identification with high mass resolution, showed that most of these carbon species were 13C-labeled. Unlike gas phase Fischer-Tropsch synthesis, no carbide was observed on mineral product surface during the experiment. Therefore, a reaction pathway is proposed for formation of dissolved linear alkane species in hydrothermal abiotic organic synthesis, where oxygen-bearing organic compounds are expected to form in aqueous products by way of alcohol and carboxyl groups on mineral catalyst surface.

  20. Submarine hydrothermal environments as sites for the origin and evolution of life

    NASA Technical Reports Server (NTRS)

    Hoffman, S.; Baross, J.

    1985-01-01

    That life formed and evolved in hydrothermal environments is proposed. This hypothesis is plausible in terms of the tectonic, paleontological, and degassing history of the Earth. Submarine hydrothermal vents are the only contemporary geological environment which may truly be called primeval and which today continue to be a major source of gases and dissolved elements to the ocean. The microbial assemblages in present day hydrothermal systems therefore could be living analogues of the earliest microbial communities to develop on Earth. The evidence for the hypothesis is reviewed.

  1. Atacamite and paratacamite from the ultramafic-hosted Logatchev seafloor vent field (14°45′N, Mid-Atlantic Ridge)

    USGS Publications Warehouse

    Dekov, Vesselin; Boycheva, Tanya; Halenius, Ulf; Petersen, Sven; Billstrom, Kjell; Stummeyer, Jens; Kamenov, G.; Shanks, W.

    2011-01-01

    Atacamite and paratacamite are ubiquitous minerals associated with Cu-rich massive sulfides at the Logatchev hydrothermal field (Mid-Atlantic Ridge). In this work we provide new details on the mineralogy and geochemistry of these basic cupric chlorides. Our data support the notion that atacamite and paratacamite formation at submarine vent fields is an alteration process of hydrothermal Cu-sulfides. Secondary Cu-sulfides (bornite, covellite) are unstable at ambient seawater conditions and will dissolve. Dissolution is focused at the sulfide–seawater contact, leading to release of Fe2+ and Cu+ and formation of residual chalcocite through an intermediate Cu5S4 phase. Most of the released Fe2+ oxidizes immediately and precipitates as FeOOH directly on the chalcocite rims whereas Cu as chloride complexes (CuCl2−, CuCl32-) remains in solution at the same Eh. Cuprous–chloride complexes migrate from the reaction zone and upon increasing Eh precipitate as Cu2Cl(OH)3. As a consequence of this, the sulfide–seawater reaction interface is clearly marked by thin chalcocite–FeOOH bands and the entire assemblage is mantled by atacamite (or paratacamite). Our mineralogical, petrographic, geochemical and isotopic studies suggest that there are two types of atacamite (and/or paratacamite) depending on their mode of precipitation. Type 1 atacamite precipitated directly on the parent sulfides as evidenced by mantling of the sulfides, absence of detrital mineral grains, a preserved conspicuous positive Eu anomaly and a negligible negative Ce anomaly similar to those of the parent sulfide. In addition, Au concentrations are slightly lower than those of the parent sulfides, which suggest minimal transport of Au-ions after their release from the sulfides. Furthermore, the low content of the rare earth elements implies short contact time with the ambient seawater. The Sr–Nd–Pb-isotopic signatures of type 1 atacamite confirm the genetic association with the parent sulfides and

  2. Hydrothermal Phase Relations Among Uranyl Minerals at the Nopal I Analog Site

    SciTech Connect

    Murphy, William M.

    2007-07-01

    Uranyl mineral paragenesis at Nopal I is an analog of spent fuel alteration at Yucca Mountain. Petrographic studies suggest a variety of possible hydrothermal conditions for uranium mineralization at Nopal I. Calculated equilibrium phase relations among uranyl minerals show uranophane stability over a broad range of realistic conditions and indicate that uranyl mineral variety reflects persistent chemical potential heterogeneity. (author)

  3. PGE fractionation in seafloor hydrothermal systems: examples from mafic- and ultramafic-hosted hydrothermal fields at the slow-spreading Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Pašava, Jan; Vymazalová, Anna; Petersen, Sven

    2007-04-01

    The distribution of platinum group elements (PGEs) in massive sulfides and hematite-magnetite±pyrite assemblages from the recently discovered basalt-hosted Turtle Pits hydrothermal field and in massive sulfides from the ultramafic-hosted Logatchev vent field both on the Mid-Atlantic Ridge was studied and compared to that from selected ancient volcanic-hosted massive sulfide (VHMS) deposits. Cu-rich samples from black smoker chimneys of both vent fields are enriched in Pd and Rh (Pd up to 227 ppb and Rh up to 149 ppb) when compared to hematite-magnetite-rich samples from Turtle Pits (Pd up to 10 ppb, Rh up to 1.9 ppb). A significant positive correlation was established between Cu and Rh in sulfide samples from Turtle Pits. PGE chondrite-normalized patterns (with a positive Rh anomaly and Pd and Au enrichment), Pd/Pt and Pd/Au ratios close to global MORB, and high values of Pd/Ir and Pt/Ir ratios indicate mafic source rock and seawater involvement in the hydrothermal system at Turtle Pits. Similarly shaped PGE chondrite-normalized patterns and high values of Pd/Pt and Pd/Ir ratios in Cu-rich sulfides at Logatchev likely reflect a similar mechanism of PGE enrichment but with involvement of ultramafic source rocks.

  4. Acoustic mapping of diffuse flow at a seafloor hydrothermal site: Monolith Vent, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Jackson, D. R.; Wen, T.; Jones, C.; Mitsuzawa, K.; Bemis, K. G.; Dworski, J. G.

    Diffuse flow of hydrothermal solutions commonly occurs in patchy areas up to tens of meters in diameter in seafloor hydrothermal fields. It is recognized as a quantitatively significant component of thermal and chemical fluxes, yet is elusive to map. We report a new acoustic method to detect and map areas of diffuse flow using phase-coherent correlation techniques. The sonar system was modified to record phase information and mounted on DSV SEA CLIFF. The submersible occupied a stationary position on the seafloor and the transducer scanned the seafloor surrounding Monolith Vent, a sulfide edifice venting black smokers, at a nominal range of 17 m at a depth of 2249 m on the Juan de Fuca Ridge. Patchy areas of uncorrelated returns clearly stood out from a background of returns that exhibited ping-to-ping correlation. The areas of uncorrelated returns coincided with areas of diffuse flow as mapped by a video survey with the Navy's Advanced Tethered Vehicle (ATV). Correlated returns were backscattered from invariant seafloor. Uncorrelated returns were distorted by index of refraction inhomogeneities as they passed through diffuse flow between the seafloor and the transducer. The acoustic method presented can synoptically map areas of diffuse flow. When combined with standard in situ measurement and sampling methods the acoustic mapping will facilitate accurate determination of diffuse thermal and chemical fluxes in seafloor hydrothermal fields.

  5. The Use of Stable Hydrogen Isotopes as a Geothermometer in Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Proskurowski, G.; Lilley, M. D.; Früh-Green, G. L.; Olson, E. J.; Kelley, D. S.

    2004-12-01

    Terrestrial geothermal work by Arnason in the 1970's demonstrated the utility of stable hydrogen isotopes as a geothermometer[1]. However, with the exception of two data points from 9°N in a study by Horibe and Craig[2], the value of this geothermometer in hydrothermal systems has never been rigorously assessed. Equilibrium fractionation factors for H2-H2O and H2-CH4 have previously been determined experimentally and theoretically over a range of temperatures and provide an expression relating alpha (fractionation) and temperature. We have measured the dD of H2(g), CH4(g) and H2O from a diverse selection of hydrothermal vent localities including Lost City, Middle Valley, Endeavour, Guaymas, Logatchev, Broken Spur, and SWIR. These samples were chosen to represent a wide range of fluid temperatures and a variety of environmental settings. We see a strong correlation between measured vent temperature and predicted vent temperature using both the hydrogen-water and the methane-hydrogen geothermometers over a temperature range of 25-400°C. In the case of the H2-H2O geothermometer, the predicted temperatures are slightly elevated with respect to the measured temperatures at the low temperature Lost City site, and are in good agreement at high temperature vent sites. The H2-CH4 geothermometer predicts temperatures that are 40-80°C elevated with respect to the measured temperature in both the low and high temperature sites. These measurements demonstrate that the hydrogen isotope geothermometer in the hydrogen-methane-water system is robust in hydrothermal systems and may be a useful tool in determining the temperature of the root zone. 1. Arnason, B., The Hydrogen-Water Isotope Thermometer Applied to Geothermal Areas In Iceland. Geothermics, 1977. 5: p. 75-80. 2. Horibe, Y. and H. Craig, D/ H fractionation in the system methane-hydrogen-water. Geochimica et Cosmochimica Acta, 1995. 59(24): p. 5209-5217.

  6. Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

    PubMed Central

    Brandstätter, Jennifer; Krenn, Kurt; Micheuz, Peter

    2016-01-01

    Abstract In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between ∼210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos‐Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high‐temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater. PMID:27570496

  7. Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

    NASA Astrophysics Data System (ADS)

    Brandstätter, Jennifer; Kurz, Walter; Krenn, Kurt; Micheuz, Peter

    2016-04-01

    In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between ˜210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos-Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high-temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater.

  8. Hydrothermal Cooling Within the Lau Integrated Study Site: No Evidence for Off-axis Discharge

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Resing, J. A.; Martinez, F.; Walker, S. L.; Buck, N.; Edwards, M. H.; Nakamura, K.

    2008-12-01

    Decades of intensive hydrothermal surveying, overwhelmingly concentrated within hundreds of meters of the axes of ridge crests, has supported the view that discrete fluid discharge is predominantly concentrated in this same region. This simple view, however, conflicts with emerging evidence for a crustal high-temperature, low-velocity volume (LVV) that extends 2-3 km beyond the ridge crest and generates strongly focused hydrothermal cooling along its off-axis vertical boundaries. In March/April 2008, we used high-resolution sampling of near-bottom waters along 175 km of the hydrothermally active Valu Fa Ridge (VFR) and Eastern Lau Spreading Center (ELSC) to comprehensively test the hypothesis that hydrothermal discharge is predominantly near-axis. Our sampling array included a suite of Miniature Autonomous Plume Recorders (temperature, light scattering, oxidation-reduction potential (ORP)) attached above (to a nominal altitude of 400 m) and below the deep-towed IMI120 sonar, plus CTDs and sensors at the bottom of the string (50 m) and on the clump weight (120 m). The ELSC between 19.9° and 21°S (spreading ~80 mm/yr) grades from a broad, flat valley in the north to a shallow high in the south. Ten survey lines at 1 km spacing were centered on the axis, plus five interleaved lines around the axial high of the ABE vent field (1300 km of track). The VFR from 21.9° to 22.4°S (~50 mm/yr) is a sharp ridge that deepens ~200 m within 1 km of the axis. Seven survey lines were run at 0.7 km spacing, plus two shorter lines adjacent to a broad overlapping spreading center (390 km). CTD tows and casts supplemented the IMI120 surveys. The surveys detected emissions from the several known on-axis vent fields, and also identified a substantial unexplored field near 20.65°S, ~10 km north of the ABE field. In neither survey area, however, did we detect evidence of high-temperature discharge beyond the near-axis (±1 km) zone. Because off-axis discharge may be largely low

  9. Hydrothermal Plume Mapping Along the Hotspot-affected Galapagos Spreading Center Finds High-Temperature Vent Sites are Anomalously Scarce

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Resing, J. A.; Walker, S. L.; Lebon, G. T.; Nakamura, K.; Haymon, R. M.; White, S. M.; MacDonald, K. C.

    2006-12-01

    Systematic searches for hydrothermal activity along midocean ridges (MORs) demonstrate that the spatial density of hydrothermal activity is a robust linear function of spreading rate. This trend argues that the availability of mantle heat is the first order control on the distribution of seafloor vent fields. However, some crustal thermal models predict that the thicker, hotter, more ductile crust associated with hotspots substantially reduces convective hydrothermal cooling, explaining observations of axial magma chambers (AMC) at shallower depths than found on normal MORs. In Dec-Jan 2006 we tested this hypothesis by mapping hydrothermal plumes overlying the hotspot-affected Galapagos Spreading Center (GSC) from 95°-89.6°W, using a dual-pass, side-scan deep tow with an array of plume sensors spanning 50- 250 m above bottom. The western GSC near 91°-92.5°W has axial-high morphology, shallow and quasi-continuous AMC, and thick (8 km) crust, changing to a transitional morphology, deeper and more discontinuous AMC, and normal (6 km) crust from 93° to 95°W. The eastern GSC, 90.5°- 89.6°W is also an axial high and presumably has crustal characteristics similar to the western GSC at 91°-92.5°W. We identified hydrothermal plumes by anomalies in light backscattering (NTU) from a vertical array of MAPR sensors along the tow line, plus redox potential (Eh) measured continuously in-situ on the tow body at a nominal elevation of 100 m. Many plumes were subsequently confirmed by CTD tows and sampling. Only three areas of extensive and intense plumes were observed: 90.52°-90.63°W, 91.78°- 91.96°W, and 94°-94.1°W. Maximum plume rise at the latter two sites exceeded 200 m, indicative of high-temperature venting that was confirmed by camera tows. Some 25 other NTU and Eh anomalies were detected along ~1000 km of trackline, but none were >5 km in length. The primary result of our survey is that hydrothermal plumes were scarce for a ridge spreading at ~60 mm

  10. Modelling of hydrothermal fluid circulation in a heterogeneous medium: Application to the Rainbow Vent site (Mid-Atlantic-Ridge, 36°14N)

    NASA Astrophysics Data System (ADS)

    Perez, F.; Mügler, C.; Jean-Baptiste, P.; Charlou, J. L.

    2012-04-01

    Hydrothermal activity at the axis of mid-ocean ridges is a key driver for energy and matter transfer from the interior of the Earth to the ocean floor. At mid-ocean ridges, seawater penetrates through the permeable young crust, warms at depth and exchanges chemicals with the surrounding rocks. This hot fluid focuses and flows upwards, then is expelled from the crust at hydrothermal vent sites in the form of black or white smokers completed by diffusive emissions. We developed a new numerical tool in the Cast3M software framework to model such hydrothermal circulations. Thermodynamic properties of one-phase pure water were calculated from the IAPWS formulation. This new numerical tool was validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also gave results in good agreement with already published simulations. We used this new numerical tool to construct a geometric and physical model configuration of the Rainbow Vent site at 36°14'N on the Mid-Atlantic Ridge. In this presentation, several configurations will be discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modelled with hydrothermal circulation in a homogeneous-permeability porous medium. We will show that these high values require the presence of a fault or a preferential pathway right below the venting site. We will propose and discuss a 2-D one-path model that allows us to simulate both high temperatures and high mass fluxes. This modelling of the hydrothermal circulation at the Rainbow site constitutes a first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field.

  11. Hydrothermal Exploration of the Mid-Atlantic Ridge, 5-10°S, using the AUV ABE and the ROV Quest a brief overview of RV Meteor Cruise M68/1

    NASA Astrophysics Data System (ADS)

    Koschinsky, A.; Devey, C.; Garbe-Schönberg, D.; German, C.; Yoerger, D.; Shank, T.

    2006-12-01

    We report a brief overview of results from a recent expedition to the first vent sites ever located on the southern Mid-Atlantic Ridge. These results are part of an on-going study by the German Ridge program, in collaboration with NOAA-OE in the USA and with NERC in the UK. During the M68/1 Cruise (April 27-June 2, 2006), we targeted three specific areas:- the 5°S area where hydrothermal fields had previously been located (German et al., EOS, 2005; Haase et al., EOS, 2005); the Nibelungen area near 8°S where strong hydrothermal plume signals had been determined (Devey et al., EOS, 2005) and the 9°S area where the shallow ridge-crest hosts diffuse hydrothermal venting (Devey et al., EOS, 2005). At 5°S, we confirmed the temperature of the hottest known hydrothermal vents issuing fluids at 407°C at 3000m water depth, corresponding directly to the critical point for seawater at these depths. In addition to revisiting the "Turtle Pits" vents and the previously discovered "Red Lion" sites we also located new high-temperature and low-temperature vents with ABE which we were able to return to and sample with Quest during a single dive day. At 8°S, we used the ABE AUV to pinpoint and photograph a new tectonically-hosted vent site situated within a non-transform discontinuity between two adjacent ridge segments similar to, for example, the Rainbow hydrothermal field on the northern Mid-Atlantic Ridge. This vent, when revisited by Quest was too vigorous to allow end-member fluid-sampling: it was extremely vigorous and situated in a crater most closely resembling those observed at the Logatchev vent-field (MAR 15°N). The atypical absence of vent-fauna at this "Drachenschlund" (Dragon's throat) vent site is currently under investigation. Finally, at 9°S we detected evidence for numerous additional low-temperature sites similar to the already known Lilliput site and all intimately associated with collapse pits in extensive lava-flows.

  12. Absolute magnetization of the seafloor at a basalt-hosted hydrothermal site: Insights from a deep-sea submersible survey

    NASA Astrophysics Data System (ADS)

    Szitkar, Florent; Dyment, Jérôme; Fouquet, Yves; Choi, Yujin; Honsho, Chie

    2015-02-01

    The analysis of high-resolution vector magnetic data acquired by deep-sea submersibles (DSSs) requires the development of specific approaches adapted to their uneven tracks. We present a method that takes advantage of (1) the varying altitude of the DSS above the seafloor and (2) high-resolution multibeam bathymetric data acquired separately, at higher altitude, by an Autonomous Underwater Vehicle, to estimate the absolute magnetization intensity and the magnetic polarity of the shallow subseafloor along the DSS path. We apply this method to data collected by DSS Nautile on a small active basalt-hosted hydrothermal site. The site is associated with a lack of magnetization, in agreement with previous findings at the same kind of sites: the contrast between nonmagnetic sulfide deposits/stockwork zone and strongly magnetized basalt is sufficient to explain the magnetic signal observed at such a low altitude. Both normal and reversed polarities are observed in the lava flows surrounding the site, suggesting complex history of accumulating volcanic flows.

  13. Hydrothermal Spinel, Corundum and Diaspore in Gabbroic Rocks from the Hess Deep Rift, IODP Site U1415

    NASA Astrophysics Data System (ADS)

    Nozaka, T.; Meyer, R.; Wintsch, R. P.

    2014-12-01

    Hydrothermal alteration of oceanic lower crust has significant implications on geophysical properties of oceanic plates and global-scale geochemical cycles. A first order observation on the hydrothermal alteration at fast-spreading ridges is provided by the gabbroic rocks recovered from the Integrated Ocean Drilling Program (IODP) Site U1415 at the Hess Deep Rift near the East Pacific Rise. Shipboard observations of these rocks have revealed an alteration sequence formed under temperature conditions ranging from amphibolite to zeolite facies with mineral assemblages including amphibole, secondary clinopyroxene, chlorite, talc, serpentine, prehnite, zeolite and clay minerals (Gillis et al., 2014). Amphibolite-facies alteration is illustrated by the tremolite-chlorite corona textures between primary olivine and plagioclase in primitive olivine gabbro or troctolite lithologies (Nozaka and Fryer, 2011). The abundance of these alteration mineral assemblages within some sampled intervals suggests localized high-temperature fluid flow near the spreading axis. Our post-cruise studies prove that some of the coronitic amphiboles, particularly those of incipient-stage corona have hornblendic compositions, suggesting a somewhat higher-temperature formation condition than tremolite. We report here another set of alteration products from Site U1415: that is, Al-spinel, corundum and diaspore. They occur in intensely altered parts of the drilled troctolites. The Al-spinel is associated with An-rich plagioclase and pargasitic amphibole that points to even higher temperature conditions than the amphibole-chlorite corona formation. The Al-spinel is partly replaced by corundum, and the corundum, in turn, is pseudomorphically replaced by diaspore. From modes of occurrence and chemical compositions of minerals, and thermodynamic calculations of the stability conditions for these mineral assemblages, we conclude that the highly aluminous phases were formed by localized fluid flow at

  14. Hydrothermal Processes

    NASA Astrophysics Data System (ADS)

    German, C. R.; von Damm, K. L.

    2003-12-01

    found at more than 40 locations throughout the Pacific, North Atlantic, and Indian Oceans (e.g., Van Dover et al., 2002) with further evidence - from characteristic chemical anomalies in the ocean water column - of its occurrence in even the most remote and slowly spreading ocean basins ( Figure 3), from the polar seas of the Southern Ocean (German et al., 2000; Klinkhammer et al., 2001) to the extremes of the ice-covered Arctic ( Edmonds et al., 2003). (61K)Figure 3. Schematic map of the global ridge crest showing the major ridge sections along which active hydrothermal vents have already been found (red circles) or are known to exist from the detection of characteristic chemical signals in the overlying water column (orange circles). Full details of all known hydrothermally active sites and plume signals are maintained at the InterRidge web-site: http://triton.ori.u-tokyo.ac.jp/~intridge/wg-gdha.htm The most spectacular manifestation of seafloor hydrothermal circulation is, without doubt, the high-temperature (>400 °C) "black smokers" that expel fluids from the seafloor along all parts of the global ocean ridge crest. In addition to being visually compelling, vent fluids also exhibit important enrichments and depletions when compared to ambient seawater. Many of the dissolved chemicals released from the Earth's interior during venting precipitate upon mixing with the cold, overlying seawater, generating thick columns of black metal-sulfide and oxide mineral-rich smoke - hence the colloquial name for these vents: "black smokers" (Figure 4). In spite of their common appearance, high-temperature hydrothermal vent fluids actually exhibit a wide range of temperatures and chemical compositions, which are determined by subsurface reaction conditions. Despite their spectacular appearance, however, high-temperature vents may only represent a small fraction - perhaps as little as 10% - of the total hydrothermal heat flux close to ridge axes. A range of studies - most notably

  15. Biogeography of bacteriophages at four hydrothermal vent sites in the Antarctic based on g23 sequence diversity.

    PubMed

    Millard, Andrew D; Pearce, David; Zwirglmaier, Katrin

    2016-04-01

    In this study, which was carried out within the ChEsSO consortium project (Chemosynthetically driven ecosystems south of the Polar Front), we sampled two hydrothermal vent sites on the East Scotia Ridge, Scotia Sea, one in the Kemp Caldera, South Sandwich Arc and one in the Bransfield Strait, north-west of the Antarctic Peninsula, which exhibit strong differences in their chemical characteristics. We compared a subset of their bacteriophage population by Sanger- and 454-sequencing of g23, which codes for the major capsid protein of T4likeviruses. We found that the sites differ vastly in their bacteriophage diversity, which reflects the differences in the chemical conditions and therefore putatively the differences in microbial hosts living at these sites. Comparing phage diversity in the vent samples to other aquatic samples, the vent samples formed a distinct separate cluster, which also included the non-vent control samples that were taken several hundred meters above the vent chimneys. This indicates that the influence of the vents on the microbial population and therefore also the bacteriophage population extends much further than anticipated.

  16. Biogeography of bacteriophages at four hydrothermal vent sites in the Antarctic based on g23 sequence diversity.

    PubMed

    Millard, Andrew D; Pearce, David; Zwirglmaier, Katrin

    2016-04-01

    In this study, which was carried out within the ChEsSO consortium project (Chemosynthetically driven ecosystems south of the Polar Front), we sampled two hydrothermal vent sites on the East Scotia Ridge, Scotia Sea, one in the Kemp Caldera, South Sandwich Arc and one in the Bransfield Strait, north-west of the Antarctic Peninsula, which exhibit strong differences in their chemical characteristics. We compared a subset of their bacteriophage population by Sanger- and 454-sequencing of g23, which codes for the major capsid protein of T4likeviruses. We found that the sites differ vastly in their bacteriophage diversity, which reflects the differences in the chemical conditions and therefore putatively the differences in microbial hosts living at these sites. Comparing phage diversity in the vent samples to other aquatic samples, the vent samples formed a distinct separate cluster, which also included the non-vent control samples that were taken several hundred meters above the vent chimneys. This indicates that the influence of the vents on the microbial population and therefore also the bacteriophage population extends much further than anticipated. PMID:26903011

  17. Multiple techniques for mineral identification on Mars:. a study of hydrothermal rocks as potential analogues for astrobiology sites on Mars

    NASA Astrophysics Data System (ADS)

    Bishop, Janice L.; Murad, Enver; Lane, Melissa D.; Mancinelli, Rocco L.

    2004-06-01

    Spectroscopic studies of Mars analog materials combining multiple spectral ranges and techniques are necessary in order to obtain ground truth information for interpretation of rocks and soils on Mars. Two hydrothermal rocks from Yellowstone National Park, Wyoming, were characterized here because they contain minerals requiring water for formation and they provide a possible niche for some of the earliest organisms on Earth. If related rocks formed in hydrothermal sites on Mars, identification of these would be important for understanding the geology of the planet and potential habitability for life. XRD, thermal properties, VNIR, mid-IR, and Raman spectroscopy were employed to identify the mineralogy of the samples in this study. The rocks studied here include a travertine from Mammoth Formation that contains primarily calcite with some aragonite and gypsum and a siliceous sinter from Octopus Spring that contains a variety of poorly crystalline to amorphous silicate minerals. Calcite was detected readily in the travertine rock using any one of the techniques studied. The small amount of gypsum was uniquely identified using XRD, VNIR, and mid-IR, while the aragonite was uniquely identified using XRD and Raman. The siliceous sinter sample was more difficult to characterize using each of these techniques and a combination of all techniques was more useful than any single technique. Although XRD is the historical standard for mineral identification, it presents some challenges for remote investigations. Thermal properties are most useful for minerals with discrete thermal transitions. Raman spectroscopy is most effective for detecting polarized species such as CO 3, OH, and CH, and exhibits sharp bands for most highly crystalline minerals when abundant. Mid-IR spectroscopy is most useful in characterizing Si-O (and metal-O) bonds and also has the advantage that remote information about sample texture (e.g., particle size) can be determined. Mid-IR spectroscopy is also

  18. Geological framework of an active hydrothermal site in the North Fiji Basin: Starmer cruise of the submersible Nautile

    SciTech Connect

    Auzende, J. )

    1990-06-01

    During the summer of 1989 the French submersible Nautile carried out a diving cruise on the North Fiji Basin ridge axis in the frame of the Starmer French-Japanese joint project. The diving sites were selected using the Seapso 3, Kaiyo 87, and Kaiyo 88 cruises Seabeam surveys. They are located around 17{degree}S in the axial graben at the northern end of the N15 ridge. The axis consists of an 18 km wide, N15 elongated dome cut by a 2 km wide axial graben. The elevation of the dome with respect to adjacent oceanic floor is 500-600 m. It culminates at less than 1,900 m, which is higher than a normal oceanic ridge. The axial graben width (2 km) is also unusual compared to oceanic ridge with intermediate spreading rates such as the EPR at 21{degree}N. Six Nautile dives have been devoted to the detailed exploration of the axial graben between 16{degree}58'S and 17{degree}00'S in order to locate the hydrothermal vents in the inferred most active part of the axial graben. A structural map has been established on the basis of dive observation. Between 17{degree}S and 16{degree}58'S, the axis shows a succession of N15-trending horsts and grabens paralleling the main orientation of the ridge. Two main lateral grabens and a central graben can be recognized. The central graben shows remarkably constant width (200 m) and depth (2,000 m). It is bounded by two small horsts, few tens of meters wide. Observed tectonic features include N15 normal fault scarps and abundant open fissures with the same direction. The whole area is dusted with sediments indicating that volcanism was not active recently. Evidence of recent hydrothermal activity such as oxide staining, dead munch, dead chimney is abundant all along the central graben.

  19. Bacteria dominate the ammonia-oxidizing community in a hydrothermal vent site at the Mid-Atlantic Ridge of the South Atlantic Ocean.

    PubMed

    Xu, Wei; Li, Meng; Ding, Jie-Fei; Gu, Ji-Dong; Luo, Zhu-Hua

    2014-09-01

    Ammonia oxidation is the first and rate-limiting step of nitrification, which is carried out by two groups of microorganisms: ammonia-oxidizing bacteria (AOB) and the recently discovered ammonia-oxidizing archaea (AOA). In this study, diversity and abundance of AOB and AOA were investigated in five rock samples from a deep-sea hydrothermal vent site at the Mid-Atlantic Ridge (MAR) of the South Atlantic Ocean. Both bacterial and archaeal ammonia monooxygenase subunit A (amoA) gene sequences obtained in this study were closely related to the sequences retrieved from deep-sea environments, indicating that AOB and AOA in this hydrothermal vent site showed typical deep ocean features. AOA were more diverse but less abundant than AOB. The ratios of AOA/AOB amoA gene abundance ranged from 1/3893 to 1/242 in all investigate samples, indicating that bacteria may be the major members responding to the aerobic ammonia oxidation in this hydrothermal vent site. Furthermore, diversity and abundance of AOA and AOB were significantly correlated with the contents of total nitrogen and total sulfur in investigated samples, suggesting that these two environmental factors exert strong influences on distribution of ammonia oxidizers in deep-sea hydrothermal vent environment.

  20. Vibrio diabolicus challenge in Bathymodiolus azoricus populations from Menez Gwen and Lucky Strike hydrothermal vent sites.

    PubMed

    Martins, Eva; Santos, Ricardo Serrão; Bettencourt, Raul

    2015-12-01

    Menez Gwen (MG) and Lucky Strike (LS) deep-sea hydrothermal vents are located at 850 m and 1730 m depths respectively and support chemosynthesis-based ecosystems partially differing in heavy metal concentration, temperature range, and faunistic composition. The successfully adapted deep-sea vent mussel Bathymodiolus azoricus is found at both vent locations. In such inhospitable environments survival strategies rely on the establishment of bacteria-vent animal symbiosis In spite of the toxic nature of deep-sea vents, the problem of microbial threat and the need for immunity exist in B. azoricus. This study aims at investigating the immune system of B. azoricus from MG and LS populations by comparing immune gene expressions profiles using the deep-sea vent-related Vibrio diabolicus. Expression of nineteen immune genes was analyzed from gill, digestive gland and mantle tissues upon 3 h, 12 h and 24 h V. diabolicus challenges. Based on quantitative-Polymerase Chain Reaction (qPCR) significant gene expression differences were found among MG and LS populations and challenge times MG mussels revealed that gill and digestive gland gene expression levels were remarkably higher than those from LS mussels. Expression of Carcinolectin, Serpin-2, SRCR, IRGs, RTK, TLR2, NF-κB, HSP70 and Ferritin genes was greater in MG than LS mussels. In contrast, mantle tissue from LS mussels revealed the highest peak of expression at 24 h for most genes analyzed. The activation of immune signaling pathways demonstrated that gene expression profiles are distinct between the two mussel populations. These differences may possibly ensue from intrinsic immune transcriptional activities upon which host responses are modulated in presence of V. diabolicus. mRNA transcript variations were assessed during 24 h acclimatization taking into account the partial depuration to which mussels were subjected to. Additionally, gene expression differences may reflect still accountable effects from the presence

  1. Vibrio diabolicus challenge in Bathymodiolus azoricus populations from Menez Gwen and Lucky Strike hydrothermal vent sites.

    PubMed

    Martins, Eva; Santos, Ricardo Serrão; Bettencourt, Raul

    2015-12-01

    Menez Gwen (MG) and Lucky Strike (LS) deep-sea hydrothermal vents are located at 850 m and 1730 m depths respectively and support chemosynthesis-based ecosystems partially differing in heavy metal concentration, temperature range, and faunistic composition. The successfully adapted deep-sea vent mussel Bathymodiolus azoricus is found at both vent locations. In such inhospitable environments survival strategies rely on the establishment of bacteria-vent animal symbiosis In spite of the toxic nature of deep-sea vents, the problem of microbial threat and the need for immunity exist in B. azoricus. This study aims at investigating the immune system of B. azoricus from MG and LS populations by comparing immune gene expressions profiles using the deep-sea vent-related Vibrio diabolicus. Expression of nineteen immune genes was analyzed from gill, digestive gland and mantle tissues upon 3 h, 12 h and 24 h V. diabolicus challenges. Based on quantitative-Polymerase Chain Reaction (qPCR) significant gene expression differences were found among MG and LS populations and challenge times MG mussels revealed that gill and digestive gland gene expression levels were remarkably higher than those from LS mussels. Expression of Carcinolectin, Serpin-2, SRCR, IRGs, RTK, TLR2, NF-κB, HSP70 and Ferritin genes was greater in MG than LS mussels. In contrast, mantle tissue from LS mussels revealed the highest peak of expression at 24 h for most genes analyzed. The activation of immune signaling pathways demonstrated that gene expression profiles are distinct between the two mussel populations. These differences may possibly ensue from intrinsic immune transcriptional activities upon which host responses are modulated in presence of V. diabolicus. mRNA transcript variations were assessed during 24 h acclimatization taking into account the partial depuration to which mussels were subjected to. Additionally, gene expression differences may reflect still accountable effects from the presence

  2. Submarine Hydrothermal Sites in Arc Volcanic-Back Arc Environment: Insight from Recent Marine Geophysical Investigations in the Southern Tyrrhenian Sea.

    NASA Astrophysics Data System (ADS)

    Cocchi, L.; Ligi, M.; Bortoluzzi, G.; Petersen, S.; Plunkett, S.; Muccini, F.; Canese, S.; Caratori Tontini, F.; Carmisciano, C.

    2014-12-01

    Hydrothermal alteration processes involve mineralogical and chemical changes, which are reflected in a major modification of potential field patterns observed over hydrothermal areas. Basalt-hosted hydrothermal sites exhibit characteristic responses with magnetic lows and minima of the gravity field. Near bottom AUV (Autonomous Underwater Vehicle) based potential field surveys have become a very effective technique in deep sea exploration. Here we present results of recent ship-borne and near seafloor magnetic and gravity investigations at deep (Marsili and Palinuro seamounts) and shallow (Panarea, Basiluzzo and Secca del Capo) hydrothermal sites in the Southern Tyrrhenian Sea including multibeam bathymetry, seafloor reflectivity and seismic profiles. At Marsili seamount, a large Fe-Mn-oxyhydroxides-rich chimney field is located at the summit (500 m depth). This site is correlated with pronounced magnetic and gravity lows (0 A/m and 2.0 g/cm3). Deep tow magnetic survey (Cruise MAVA11) revealed strong association between the complicated magnetization pattern and the main volcano-tectonic features of the ridge. Hydrothermal manifestations at Palinuro seamount occur mainly on the western sector within the rim of a caldera structure at depth of 600m. Recent AUV based magnetic surveys (Cruise POS442, 2012 using AUV "Abyss") detailed a magnetization low interpreted to represent the local distribution of subseafloor hydrothermal alteration (potentially massive sulfide deposits), and also mapped previously undiscovered inactive chimney fields. Hydrothermal sites observed at the arc-related volcanic islands (Panarea, Basiluzzo, Eolo and Secca del Capo) are confined to shallow depths (less then 300m) and associated with large ochreaceous mounds, vents and chimney fields such as those observed E of Basiluzzo Island. At this site a recent magnetic survey (Cruise PANA13_ASTREA) combined with Remote Operated Vehicle (ROV) investigations revealed that the submarine geothermal

  3. Application of radium isotopes to determine crustal residence times of hydrothermal fluids from two sites on the Reykjanes Peninsula, Iceland

    NASA Astrophysics Data System (ADS)

    Kadko, David; Gronvold, Karl; Butterfield, David

    2007-12-01

    Radium isotopes were used to determine the crustal residence times of hydrothermal fluids from two geothermal wells (Svartsengi and Reykjanes) from the Reykjanes Peninsula, Iceland. The availability of rock samples from the subsurface (to depths of 2400 m) allowed direct comparison of the radium isotopic characteristics of the fluids with those of the rocks within the high temperature and pressure reaction zone. The 226Ra activity of the Svartsengi fluid was ˜one-fourth of the Reykjanes fluid and the 228Ra/ 226Ra ratio of the Svartsengi fluid was ˜twice that of Reykjanes. The fluid isotopic characteristics were relatively stable for both sites over the 6 years (2000-2006) of the study. It was determined, using a model that predicts the evolution of the fluid 228Ra/ 226Ra ratio with time, that both sites had fluid residence times, from the onset of high temperature water-rock reaction, of less than 5 years. Measurement of the short-lived 224Ra and 223Ra allowed estimation of the recoil input parameter used in the model. The derived timescale is consistent with results from similar studies of fluids from submarine systems, and has implications for the use of terrestrial systems in Iceland as an exploited energy resource.

  4. High-resolution magnetics reveal the deep structure of a volcanic-arc-related basalt-hosted hydrothermal site (Palinuro, Tyrrhenian Sea)

    NASA Astrophysics Data System (ADS)

    Szitkar, Florent; Petersen, Sven; Caratori Tontini, Fabio; Cocchi, Luca

    2015-06-01

    High-resolution magnetic surveys have been acquired over the partially sedimented Palinuro massive sulfide deposits in the Aeolian volcanic arc, Tyrrhenian Sea. Surveys flown close to the seafloor using an autonomous underwater vehicle (AUV) show that the volcanic-arc-related basalt-hosted hydrothermal site is associated with zones of lower magnetization. This observation reflects the alteration of basalt affected by hydrothermal circulation and/or the progressive accumulation of a nonmagnetic deposit made of hydrothermal and volcaniclastic material and/or a thermal demagnetization of titanomagnetite due to the upwelling of hot fluids. To discriminate among these inferences, estimate the shape of the nonmagnetic deposit and the characteristics of the underlying altered area—the stockwork—we use high-resolution vector magnetic data acquired by the AUV Abyss (GEOMAR) above a crater-shaped depression hosting a weakly active hydrothermal site. Our study unveils a relatively small nonmagnetic deposit accumulated at the bottom of the depression and locked between the surrounding volcanic cones. Thermal demagnetization is unlikely but the stockwork extends beyond the limits of the nonmagnetic deposit, forming lobe-shaped zones believed to be a consequence of older volcanic episodes having contributed in generating the cones.

  5. Anhydrite precipitation in seafloor hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

    The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists

  6. Immunomodulatory N-acyl Dopamine Glycosides from the Icelandic Marine Sponge Myxilla incrustans Collected at a Hydrothermal Vent Site.

    PubMed

    Einarsdottir, Eydis; Liu, Hong-Bing; Freysdottir, Jona; Gotfredsen, Charlotte Held; Omarsdottir, Sesselja

    2016-06-01

    A chemical investigation of the sponge (Porifera) Myxilla incrustans collected from the unique submarine hydrothermal vent site Strytan, North of Iceland, revealed a novel family of closely related N-acyl dopamine glycosides. Three new compounds, myxillin A (1), B (2) and C (3), were isolated and structurally elucidated using several analytical techniques, such as HR-MS, 1D and 2D NMR spectroscopy. Myxillin A (1) and B (2)were shown to be structurally similar, composed of a dopamine moiety, but differ in the acyl chain length and saturation. The myxillin C (3) has a dehydrotyrosine moiety composing the same acyl chain and glycosylation as myxillin B (2). Myxillins A (1) and C (3) were tested for immunomodulating activity in an in vitro dendritic cell model. Dendritic cells matured and stimulated in the presence of myxillin A (1) secreted lower levels of IL-12p40, whilst dendritic cells matured and stimulated in the presence of myxillin C (3) secreted lower levels of IL-10 compared with dendritic cells matured and stimulated in the presence of the solvent alone. These opposing results indicate that the structural differences in the aromatic ring part of the molecules could have an impact on the immunological effects of dendritic cells. These molecules could, therefore, prove to be important in preventing inflammatory diseases on the one hand, and inducing a response to fight tumors and/or pathogens on the other hand. Further studies will be needed to confirm these potential uses. PMID:27135626

  7. Chemosynthetic microbial activity at Mid-Atlantic Ridge hydrothermal vent sites

    NASA Astrophysics Data System (ADS)

    Wirsen, Carl O.; Jannasch, Holger W.; Molyneaux, Stephen J.

    1993-06-01

    Chemosynthetic production of microbial biomass, determined by 14CO2 fixation and enzymatic (RuBisCo) activity, at the Mid-Atlantic Ridge (MAR) 23° and 26°N vent sites was found in various niches: warm water emissions, loosely rock-attached flocculent material, dense morphologically diverse bacterial mats covering the surfaces of polymetal sulfide deposits, and filamentous microbes on the carapaces of shrimp (Rimicaris exoculata). The bacterial mats on polymetal sulfide surfaces contained unicellular and filamentous bacteria which appeared to use as their chemolithotrophic electron or energy source either dissolved reduced minerals from vent emissions, mainly sulfur compounds, or solid metal sulfide deposits, mainly pyrite. Moderately thermophilic Chemosynthetic activity was observed in carbon dioxide fixation experiments and in enrichments, but no thermophilic aerobic sulfur oxidizers could be isolated. Both obligate and facultative chemoautotrophs growing at mesophilic temperatures were isolated from all chemosynthetically active surface scrapings. The obligate autotrophs could oxidize sterilized MAR natural sulfide deposits as well as technical pyrite at near neutral pH, in addition to dissolved reduced sulfur compounds. While the grazing by shrimp on the surface mats of MAR metal sulfide deposits was observed and deemed important, the animals' primary occurrence in dense swarms near vent emissions suggests that they were feeding at these sites, where conditions for Chemosynthetic growth of their filamentous microbial epiflora were optimal. The data show that the transformation of geothermal energy at the massive polymetal sulfide deposits of the MAR is based on the lithoautotrophic oxidation of soluble sulfides and pyrites into microbial biomass.

  8. Interactions Between Serpentinization, Hydrothermal Activity and Microbial Community at the Lost City Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Delacour, A.; Frueh-Green, G. L.; Bernasconi, S. M.; Schaeffer, P.; Frank, M.; Gutjahr, M.; Kelley, D. S.

    2008-12-01

    Seafloor investigations of slow- and ultraslow-spreading ridges have reported many occurrences of exposed mantle peridotites and gabbroic rocks on the ocean floor. Along the Mid-Atlantic Ridge, these uplifted portions of oceanic crust host high-temperature black smoker-type hydrothermal systems (e.g., Rainbow, Logatchev, Saldanha), and the more distinct low-temperature Lost City Hydrothermal Field (LCHF). Built on a southern terrace of the Atlantis Massif, the LCHF is composed of carbonate-brucite chimneys that vent alkaline and low-temperature (40-90°C) hydrothermal fluids. These fluids are related to serpentinization of mantle peridotites, which together with minor gabbroic intrusions form the basement of the LCHF. Long-lived hydrothermal activity at Lost City led to extensive seawater-rock interaction in the basement rocks, as indicated by seawater-like Sr- and mantle to unradiogenic Nd-isotope compositions of the serpentinites. These high fluid fluxes in the southern part of the massif influenced the conditions of serpentinization and have obliterated the early chemical signatures in the serpentinites, especially those of carbon and sulfur. Compared to reducing conditions commonly formed during the first stages of serpentinization, serpentinization at Lost City is characterized by relatively oxidizing conditions resulting in a predominance of magnetite, the mobilization/dissolution and oxidation of igneous sulfides to secondary pyrite, and the incorporation of seawater sulfate, all leading to high bulk-rock S-isotope compositions. The Lost City hydrothermal fluids contain high concentrations in methane, hydrogen, and low-molecular weight hydrocarbons considered as being produced abiotically. In contrast, organic compounds in the serpentinites are dominated by the occurrences of isoprenoids (pristane, phytane, and squalane), polycyclic compounds (hopanes and steranes), and higher abundances of C16 to C20 n-alkanes indicative of a marine organic input. We

  9. Site-related differences in gene expression and bacterial densities in the mussel Bathymodiolus azoricus from the Menez Gwen and Lucky Strike deep-sea hydrothermal vent sites.

    PubMed

    Bettencourt, Raul; Rodrigues, Mónica; Barros, Inês; Cerqueira, Teresa; Freitas, Cátia; Costa, Valentina; Pinheiro, Miguel; Egas, Conceição; Santos, Ricardo Serrão

    2014-08-01

    The deep-sea hydrothermal vent mussel Bathymodiolus azoricus is a symbiont bearing bivalve that is found in great abundance at the Menez Gwen and Lucky Strike hydrothermal vent sites and in close vicinity of the Azores region near the Mid-Atlantic Ridge (MAR). The physiological relationships that vent mussels have developed with their physical and chemical environments are likely to influence global gene expression profiles providing thus the means to investigate distinct biological markers predicting the origin of Bathymodiolus sp. irrespectively of their geographical localization. Differences found at gene expression levels, and between fluorescence in situ hybridization (FISH) and 16S rRNA amplicon sequencing results provided experimental evidence for the distinction of both Menez Gwen and Lucky Strike vent mussel individuals based on bacterial and vent mussel gene expression signatures and on the constitutive distribution and relative abundance of endosymbiotic bacteria within gill tissues. Our results confirmed the presence of methanotroph endosymbionts in Menez Gwen vent mussels whereas Lucky Strike specimens seem to harbor a different bacterial morphotype when a methane monooxygenase gene specific probe was used. No qualitative differences could be visualized between Menez Gwen and Lucky Strike individuals when tested with a sulfur-oxidizing-related probe. Quantitative PCR (qPCR) studies revealed different gene expression profiles in both Menez Gwen and Lucky Strike mussel gill tissues for the immune genes selected. Genes encoding transcription factors presented noticeably low levels of fold expression whether in Menez Gwen or Lucky Strike animals whereas the genes encoding effector molecules appeared to have higher levels expression in gill tissues from Menez Gwen animals. The peptidoglycan recognition molecule encoding gene, PGRP, presented the highest level of transcriptional activity among the genes analyzed in Menez Gwen mussel gill tissues, seconded by

  10. Site-related differences in gene expression and bacterial densities in the mussel Bathymodiolus azoricus from the Menez Gwen and Lucky Strike deep-sea hydrothermal vent sites.

    PubMed

    Bettencourt, Raul; Rodrigues, Mónica; Barros, Inês; Cerqueira, Teresa; Freitas, Cátia; Costa, Valentina; Pinheiro, Miguel; Egas, Conceição; Santos, Ricardo Serrão

    2014-08-01

    The deep-sea hydrothermal vent mussel Bathymodiolus azoricus is a symbiont bearing bivalve that is found in great abundance at the Menez Gwen and Lucky Strike hydrothermal vent sites and in close vicinity of the Azores region near the Mid-Atlantic Ridge (MAR). The physiological relationships that vent mussels have developed with their physical and chemical environments are likely to influence global gene expression profiles providing thus the means to investigate distinct biological markers predicting the origin of Bathymodiolus sp. irrespectively of their geographical localization. Differences found at gene expression levels, and between fluorescence in situ hybridization (FISH) and 16S rRNA amplicon sequencing results provided experimental evidence for the distinction of both Menez Gwen and Lucky Strike vent mussel individuals based on bacterial and vent mussel gene expression signatures and on the constitutive distribution and relative abundance of endosymbiotic bacteria within gill tissues. Our results confirmed the presence of methanotroph endosymbionts in Menez Gwen vent mussels whereas Lucky Strike specimens seem to harbor a different bacterial morphotype when a methane monooxygenase gene specific probe was used. No qualitative differences could be visualized between Menez Gwen and Lucky Strike individuals when tested with a sulfur-oxidizing-related probe. Quantitative PCR (qPCR) studies revealed different gene expression profiles in both Menez Gwen and Lucky Strike mussel gill tissues for the immune genes selected. Genes encoding transcription factors presented noticeably low levels of fold expression whether in Menez Gwen or Lucky Strike animals whereas the genes encoding effector molecules appeared to have higher levels expression in gill tissues from Menez Gwen animals. The peptidoglycan recognition molecule encoding gene, PGRP, presented the highest level of transcriptional activity among the genes analyzed in Menez Gwen mussel gill tissues, seconded by

  11. Hydrothermal Processing

    SciTech Connect

    Elliott, Douglas C.

    2011-03-11

    This chapter is a contribution to a book on Thermochemical Conversion of Biomass being edited by Prof. Robert Brown of Iowa State University. It describes both hydrothermal liquefaction and hydrothermal gasification of biomass to fuels.

  12. Noble Gas geochemistry of the newly discovered hydrothermal fields in the Gulf of California: preliminary He-isotope ratios from the Alarcon Rise and Pescadero basin vent sites

    NASA Astrophysics Data System (ADS)

    Spelz, R. M.; Lupton, J. E.; Evans, L. J.; Zierenberg, R. A.; Clague, D. A.; Neumann, F.; Paduan, J. B.

    2015-12-01

    Numerous submarine deep-sea hydrothermal vents related to volcanic activity of the East Pacific Rise (EPR) are situated along the Pacific margins of Mexico. Until recently, active hydrothermal venting was unknown between the Guaymas Basin and 21°N on the EPR. MBARI's recent oceanographic surveys have added 7 new active vent sites. In this study, we aimed to sample the high-temperature hydrothermal fluids emanating from two distinct vent sites, named Meyibo and Auka, located in the Alarcon Rise and Pescadero Basin, respectively. Mantle-derived He have long been identified in hydrothermal fluid releases. The presence of He in aqueous fluids with 3He/4He ratios greater than in-situ production values (~0.05 RA, where RA = air He or 1.4 x 10-6) indicates the presence of mantle-derived melts. Preliminary analyses of He-isotope ratios derived from the newly discovered Meyibo and Auka hydrothermal fields show high 3He/4He ratios (~8RA), typical of MORB's. Auka vent field, characterized by chimneys composed of light carbonate minerals and oil-like hydrocarbons, and temperatures between 250-290oC, show average values of ~7.87RA. In contrast, the black-smokers at the Meyibo field, composed of dark sulfide minerals and temperatures over 350oC, yielded a higher He ratio of ~8.24RA. Recently, it has become clear that regional maximum mantle He values correlate with the velocity structure in the mantle, therefore, He has the potential to map regions of the underlying mantle that are undergoing partial melting. Seismic records could then be compared with the geochemical He ratio signal and supply information regarding tectonics and other processes involved in the generation of these gases. The data presented here will be completing a totally new inventory of He results from hydrothermal vents in the EPR and fault-termination basins distributed along the P-NA plate boundary in the Gulf of California. The results will be further coupled with the analysis of other geochemical

  13. Fluid inclusion petrography and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

    NASA Astrophysics Data System (ADS)

    Brandstätter, J.; Kurz, W.; Krenn, K.; Micheuz, P.

    2015-12-01

    We present new data from microthermometric analyses of fluid inclusions entrapped in hydrothermal veins within lithified sediments and Cocos Ridge (CCR) basalt from IODP Expedition 344 site U1414 (Costa Rica) and concern on a primary task of Expedition 344, i.e. to evaluate fluid/rock interaction, the hydrologic system, and the geochemical processes (indicated by composition and volume of fluids) active within the incoming Cocos Plate. Mineralization of the veins and crosscutting relationships gives constraints for the different generation of veins. Calcium carbonate, commonly aragonite in the upper part and calcite in the lower part of the igneous basement, is usually present in veins as a late phase following the quartz precipitation and the clay minerals formation. The sequence of vein generations in the lithified sediments close to the contact within the CCR basalt is characterized by smaller veins filled by quartz, followed by massive intersecting calcite veins. A high fluid pressure can be concluded, due to wall rock fragments embedded within the filling and fractured mineral grains in the ground mass, which are close to the veins. This requires that the magmatic basement and the lithified sediments were covered by sequences of low permeability sediments forming a barrier that enabled build up elevated fluid pressure. The investigation of fluid inclusions in the lowest units of borehole 344-U1414, give clues about the source of the fluids and about the vein evolution within the incoming Cocos Plate close to Middle American Trench. The microthermometric analyses of the primary, almost aqueous, inclusions indicate a temperature range during entrapment between 200 and 420°C. The data indicate that seawater within the Cocos Ridge aquifer communicated with high-temperature fluids and/or were modified by heat advection. We consider the Galapagos hotspot and/ or the Cocos-Nazca spreading center as heat source. Fluids originated from mobilized sediment pore water

  14. Correlation of the changes in the framework and active Cu sites for typical Cu/CHA zeolites (SSZ-13 and SAPO-34) during hydrothermal aging.

    PubMed

    Su, Wenkang; Li, Zhenguo; Peng, Yue; Li, Junhua

    2015-11-21

    The relative framework stability of Cu/CHA zeolites (SAPO-34 and SSZ-13) was studied during hydrothermal aging at 800 °C, and the fundamental mechanism for the framework change was investigated. Additionally, the relationship between the variation in the framework and active SCR reaction sites was established. SAPO-34 showed stronger stability during hydrothermal aging than SSZ-13. The results showed that dealumination occurred in the SSZ-13 zeolite, leading to the loss of crystallinity and a severe decrease of the Brönsted acid sites. Simultaneously, the detached Al(OH)3 species deactivated the Cu species by the transformation of isolated Cu(2+) ions to CuAlOx species. While the vacancy in the SAPO-34 framework caused by desilication could be healed with the migration of extra-framework Al and P atoms to the defects. And the Cu species showed a certain degree of aggregation with the improved redox ability of the aged Cu/SAPO-34 zeolite and the acidic properties were well maintained. PMID:26462874

  15. Transfer and partitioning of energy and mass through seafloor hydrothermal systems: comparative studies at the Ridge2000 Integrated Study Sites (ISS) (Invited)

    NASA Astrophysics Data System (ADS)

    Tivey, M. K.

    2010-12-01

    Seafloor hydrothermal systems are major players in the transfer of mass and energy from the mantle and crust to the ocean and biosphere. Over the past thirty years, much has been learned about this transfer to the ocean, but considerably less is known about the transfer to the biosphere. Study of hydrothermal systems in a diverse range of geologic settings has shown relationships between spreading rate and hydrothermal heat flux, substrate composition (including rock geochemistry, presence/absence of sediment) and hydrothermal fluid composition, and magmatic/tectonic events and temporal variability of fluid composition (e.g., German and Von Damm, Treatise On Geochemistry, 2004; Baker et al. AGU Monograph Series 91, 1995). Studies in arc and back-arc settings are documenting the effects of magmatic acid volatiles on fluid-rock reaction and fluid and vent deposit compositions (e.g., Ishibashi and Urabe, Backarc Basins: Tectonics and Magmatism, 1995). These comparative studies in a wide range of geologic settings, including at the three Ridge2000 ISS, have provided a fairly good understanding of the flux of heat and many elements to the ocean associated with high temperature seafloor hydrothermal systems. Considerably less is known, however, about the partitioning of heat and mass (particularly metals and sulfur) in hydrothermal systems. The deposits that form at vent sites are intimately linked within paths of energy and mass transport from the mantle and crust to the oceans. Transport differs greatly through different types of deposits (e.g., black smokers, white smokers/diffusers, flanges). Estimates of heat flux from measured temperatures of flow (unless integrated over and around an entire vent field) require an understanding of the partitioning of flow between focused black smokers and more diffuse flow from diffusers, flanges, and surfaces of deposits, and from the igneous substrate. Estimates of mass flux into the ocean require an understanding of the

  16. Time Series Studies of Faunal Colonization and Temperature Variations at Diffuse-Flow Hydrothermal Vent Sites Near 9° 50'N, EPR

    NASA Astrophysics Data System (ADS)

    Shank, T. M.; Scheirer, D.; Fornari, D. J.

    2001-12-01

    conditions. Spectral analysis of the temperature probe data in diffuse-flow vent sites indicate that variations in the hydrothermal fluid temperature experienced by vent fauna are influenced by: (1) tidal and primary vent flux oscillations, (2) microhabitat structure associated with different patterns of community development, and (3) geological parameters, such as local geological setting, local and regional crustal permeability, and proximity to high-temperature venting. The spectral character of the measured temperature fluctuations varies significantly over distance scales of tens of centimeters and greater, from the center of a diffuse-flow field to its edges and from the seafloor upwards. Correlation with predicted tidal variations and measured currents, for parts of the temperature records, indicate an important, but not exclusive, tidal component governing the temperature variations. Significant fluctuations in temperature occur at periods different from tidal periods and their harmonics. Thus, local geological and biological structures and processes are key elements to understanding the physical and ecological changes in this dynamic environment.

  17. Hydrothermal alteration of a chevkinite-group mineral to a bastnäsite-(Ce)-ilmenite- columbite-(Fe) assemblage: interaction with a F-, CO2-rich fluid

    NASA Astrophysics Data System (ADS)

    Macdonald, Ray; Bagiński, Bogusław; Kartashov, Pavel M.; Zozulya, Dmitry; Dzierżanowski, Piotr; Jokubauskas, Petras

    2015-12-01

    The results are presented of a textural and mineral chemical study of a previously undescribed type of hydrothermal alteration of chevkinite-(Ce) which occurs in a syenitic pegmatite from the Vishnevye Mountains, Urals Region, Russia. The progressive alteration of the chevkinite to a bastnäsite-(Ce)-ilmenite-columbite-(Fe) assemblage through a series of texturally complex intermediate stages is described and electron microprobe analyses are given of all the major phases. Unusual Nb ± Th-rich phases formed late in the alteration sequence provide evidence of local Nb mobility. The main compositional fluxes are traced, especially of the REE, HFSE, Th and U. It appears that almost all elements, with the exception of La, released from the chevkinite-(Ce) were reincorporated into later phases, such that they did not leave the alteration crust in significant amounts. The hydrothermal fluids are inferred to have been F- and CO2-rich, with variable levels of Ca activity, and with fO2 mainly between the nickel-nickel oxide and magnetite-hematite buffers. This occurrence represents a new paragenesis for a columbite-group mineral.

  18. Isolation and complete genome sequence of the thermophilic Geobacillus sp. 12AMOR1 from an Arctic deep-sea hydrothermal vent site.

    PubMed

    Wissuwa, Juliane; Stokke, Runar; Fedøy, Anita-Elin; Lian, Kjersti; Smalås, Arne Oskar; Steen, Ida Helene

    2016-01-01

    Members of the genus Geobacillus have been isolated from a wide variety of habitats worldwide and are the subject for targeted enzyme utilization in various industrial applications. Here we report the isolation and complete genome sequence of the thermophilic starch-degrading Geobacillus sp. 12AMOR1. The strain 12AMOR1 was isolated from deep-sea hot sediment at the Jan Mayen hydrothermal Vent Site. Geobacillus sp. 12AMOR1 consists of a 3,410,035 bp circular chromosome and a 32,689 bp plasmid with a G + C content of 52 % and 47 %, respectively. The genome comprises 3323 protein-coding genes, 88 tRNA species and 10 rRNA operons. The isolate grows on a suite of sugars, complex polysaccharides and proteinous carbon sources. Accordingly, a versatility of genes encoding carbohydrate-active enzymes (CAZy) and peptidases were identified in the genome. Expression, purification and characterization of an enzyme of the glycoside hydrolase family 13 revealed a starch-degrading capacity and high thermal stability with a melting temperature of 76.4 °C. Altogether, the data obtained point to a new isolate from a marine hydrothermal vent with a large bioprospecting potential. PMID:26913091

  19. Isolation and complete genome sequence of the thermophilic Geobacillus sp. 12AMOR1 from an Arctic deep-sea hydrothermal vent site.

    PubMed

    Wissuwa, Juliane; Stokke, Runar; Fedøy, Anita-Elin; Lian, Kjersti; Smalås, Arne Oskar; Steen, Ida Helene

    2016-01-01

    Members of the genus Geobacillus have been isolated from a wide variety of habitats worldwide and are the subject for targeted enzyme utilization in various industrial applications. Here we report the isolation and complete genome sequence of the thermophilic starch-degrading Geobacillus sp. 12AMOR1. The strain 12AMOR1 was isolated from deep-sea hot sediment at the Jan Mayen hydrothermal Vent Site. Geobacillus sp. 12AMOR1 consists of a 3,410,035 bp circular chromosome and a 32,689 bp plasmid with a G + C content of 52 % and 47 %, respectively. The genome comprises 3323 protein-coding genes, 88 tRNA species and 10 rRNA operons. The isolate grows on a suite of sugars, complex polysaccharides and proteinous carbon sources. Accordingly, a versatility of genes encoding carbohydrate-active enzymes (CAZy) and peptidases were identified in the genome. Expression, purification and characterization of an enzyme of the glycoside hydrolase family 13 revealed a starch-degrading capacity and high thermal stability with a melting temperature of 76.4 °C. Altogether, the data obtained point to a new isolate from a marine hydrothermal vent with a large bioprospecting potential.

  20. Using in situ voltammetry as a tool to identify and characterize habitats of iron-oxidizing bacteria: from fresh water wetlands to hydrothermal vent sites.

    PubMed

    MacDonald, Daniel J; Findlay, Alyssa J; McAllister, Sean M; Barnett, Josh M; Hredzak-Showalter, Patricia; Krepski, Sean T; Cone, Shane G; Scott, Jarrod; Bennett, Sarah K; Chan, Clara S; Emerson, David; Luther Iii, George W

    2014-09-20

    Iron-oxidizing bacteria (FeOB) likely play a large role in the biogeochemistry of iron, making the detection and understanding of the biogeochemical processes FeOB are involved in of critical importance. By deploying our in situ voltammetry system, we are able to measure a variety of redox species, specifically Fe(ii) and O2, simultaneously. This technique provides significant advantages in both characterizing the environments in which microaerophilic FeOB are found, and finding diverse conditions in which FeOB could potentially thrive. Described here are four environments with different salinities [one fresh groundwater seep site, one beach-groundwater mixing site, one hydrothermal vent site (Mid-Atlantic Ridge), and one estuary (Chesapeake Bay)] where in situ voltammetry was deployed, and where the presence of FeOB were confirmed by either culturing methods or molecular data. The sites varied in both O2 and Fe(ii) content with O2 ranging from below the 3 μM detection limit of the electrodes at the Chesapeake Bay suboxic zone, to as high 150 μM O2 at the vent site. In addition, a range of Fe(ii) concentrations supported FeOB communities, from 3 μM Fe(ii) in the Chesapeake Bay to 300 μM in the beach aquifer. In situ electrochemistry provides the means to quickly measure these redox gradients at appropriate resolution, making it possible in real time to detect niches likely inhabited by microaerophilic FeOB, then accurately sample for proof of FeOB presence and activity. This study demonstrates the utility of this approach while also greatly expanding our knowledge of FeOB habitats. PMID:24924809

  1. Using in situ voltammetry as a tool to identify and characterize habitats of iron-oxidizing bacteria: from fresh water wetlands to hydrothermal vent sites.

    PubMed

    MacDonald, Daniel J; Findlay, Alyssa J; McAllister, Sean M; Barnett, Josh M; Hredzak-Showalter, Patricia; Krepski, Sean T; Cone, Shane G; Scott, Jarrod; Bennett, Sarah K; Chan, Clara S; Emerson, David; Luther Iii, George W

    2014-09-20

    Iron-oxidizing bacteria (FeOB) likely play a large role in the biogeochemistry of iron, making the detection and understanding of the biogeochemical processes FeOB are involved in of critical importance. By deploying our in situ voltammetry system, we are able to measure a variety of redox species, specifically Fe(ii) and O2, simultaneously. This technique provides significant advantages in both characterizing the environments in which microaerophilic FeOB are found, and finding diverse conditions in which FeOB could potentially thrive. Described here are four environments with different salinities [one fresh groundwater seep site, one beach-groundwater mixing site, one hydrothermal vent site (Mid-Atlantic Ridge), and one estuary (Chesapeake Bay)] where in situ voltammetry was deployed, and where the presence of FeOB were confirmed by either culturing methods or molecular data. The sites varied in both O2 and Fe(ii) content with O2 ranging from below the 3 μM detection limit of the electrodes at the Chesapeake Bay suboxic zone, to as high 150 μM O2 at the vent site. In addition, a range of Fe(ii) concentrations supported FeOB communities, from 3 μM Fe(ii) in the Chesapeake Bay to 300 μM in the beach aquifer. In situ electrochemistry provides the means to quickly measure these redox gradients at appropriate resolution, making it possible in real time to detect niches likely inhabited by microaerophilic FeOB, then accurately sample for proof of FeOB presence and activity. This study demonstrates the utility of this approach while also greatly expanding our knowledge of FeOB habitats.

  2. Differential gene expression in the mussel Bathymodiolus azoricus from the Menez Gwen and Lucky Strike deep-sea hydrothermal vent sites

    NASA Astrophysics Data System (ADS)

    Bettencourt, R.; Rodrigues, M. I.; Barros, I.; Cerqueira, T.; Freitas, C.; Costa, V.; Pinheiro, M.; Egas, C.; Santos, R. S.

    2013-02-01

    The deep-sea hydrothermal vent mussel Bathymodiolus azoricus is a symbiont bearing bivalve that is found in great abundance at the Menez Gwen and Lucky Strike vent sites and in close vicinity off the Azores region near the Mid-Atlantic Ridge (MAR). The distinct relationships that vent mussels have developed with their physical and chemical environments are likely reflected in global gene expression profiles providing thus a means to distinguish geographically distinct vent mussels on the basis of gene expression studies, fluorescence in situ hybridization (FISH) experiments and 16S rRNA amplicon sequencing, to assess the natural expression of bacterial genes and vent mussel immune genes and the constitutive distribution and relative abundance of endosymbiotic bacteria within gill tissues. Our results confirmed the presence of methanotroph-related endosymbionts in Menez Gwen vent mussels whereas Lucky Strike specimens seem to harbor a different bacterial morphotype when a methane monooxygenase gene specific probe was used. No qualitative differences could be visualized between Menez Gwen and Lucky Strike individuals when tested with sulfur-oxidizing-related nucleic-acid probe. Quantitative PCR (qPCR) studies revealed varied gene expression profiles in both Menez Gwen and Lucky Strike mussel gill tissues for the immune genes selected. Genes encoding transcription factors presented noticeably low levels of fold expression whether in MG or LS animals whereas the genes encoding effector molecules appeared to have higher levels expression in MG gill tissues. The peptidoglycan recognition molecule, encoding gene, PGRP presented the highest level of transcriptional activity among the genes analyzed in MG gill tissues, seconded by carcinolectin and thus denoting the relevance of immune recognition molecules in early stage of the immune responses onset. Genes regarded as encoding molecules involved in signaling pathways were consistently expressed in both MG and LS gill

  3. Fluid Geochemistry of the Capelinhos Vent Site. A Key to Understand the Lucky Strike Hydrothermal Vent Field (37°N, MAR).

    NASA Astrophysics Data System (ADS)

    Leleu, T.; Chavagnac, V.; Cannat, M.; Ceuleneer, G.; Castillo, A.; Menjot, L.

    2015-12-01

    The Lucky Strike hydrothermal field is situated at the mid-Atlantic ridge, south of the Azores, on top of a central volcano within the axial valley. The volcano is composed of a fossil lava lake surrounded by three volcanic cones. An Axial Magma Chamber (AMC) is reported 3.4km below the seafloor. The active venting sites are situated around the fossil lava lake and are directly linked to the heat supplied by the AMC. High temperature fluids from the Lucky Strike field were sampled in 2013, 2014 and 2015 in order to document the depth of the reaction zone, subsurface mixing, geographical control and magmatic degassing. A new active site named Capelinhos was discovered approximately 1.5km eastward from the lava lake, during exploration by ROV Victor6000 - MoMARsat cruise, 2013. It is composed of 10m-high chimneys discharging black smoker-type fluid. Fluid temperatures were 328°C in 2013 and decreased to 318°C in 2014 and 2015. Capelinhos fluids are Cl-depleted by 55% compared to seawater indicating phase separation at depth. In comparison, the other sites range from 6% enrichment (2608/Y3 site) to 22% depletion (Eiffel tower site). Si geothermobarometry of Y3 site estimates quartz equilibration at P=300 bars and T=360-380°C, coherent with Fe/Mn geothermometer (T=370±10°C). For Capelinhos, Fe/Mn suggests 398°C (±10°C) which is close to the critical point of seawater (P=300 bars and T=407°C). Other geothermobarometer uses Si/Cl vapor-like fluid to constrain depth of the top of reaction zone and predicts significant bias due to mixing along the up-flow zone. Application gives P=~370 bars, T=~435°C at Capelinhos and P=~390 bars, T=~440°C at Eiffel tower. This is further sustained by end-member 87Sr/86Sr=0.7038, which indicates little interaction of Capelinhos vent fluids with seawater-derived fluid, compared to other vapor-like sites with 87Sr/86Sr=0.7043. Because of its external location, Capelinhos site isn't influenced by the complex tectonic context of the

  4. High-Temperature Hydrothermal Vent Field of Kolumbo Submarine Volcano, Aegean Sea: Site of Active Kuroko-Type Mineralization

    NASA Astrophysics Data System (ADS)

    Sigurdsson, H.; Carey, S.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

    2006-12-01

    Kolumbo submarine volcano is located 7 km north-east of the island of Santorini in the Hellenic arc (Greece), and comprises one of about twenty submarine cones in a NE-trending rift zone. Kolumbo erupted explosively in 1649-50AD, causing 70 fatalities on Santorini. Kolumbo's crater is 1700 m in diameter, with a crater rim at 10 m below sea level and crater floor at depth of 505 m. Recent marine geological investigations, using ROVs, reveal a very active high-temperature hydrothermal vent field in the northeastern part of the Kolumbo crater floor, about 25,000 m2. Vent chimneys up to 4 m high are vigorously emitting colorless gas plumes up to 10 m high in the water column. Temperatures up to 220oC are recorded in vent fluids. Some vents are in crater- like depressions, containing debris from collapsed extinct chimneys. The entire crater floor of Kolumbo is mantled by a reddish-orange bacterial mat, and bacterial filaments of a variety of colors cling to chimneys in dense clusters. Glassy tunicates and anemones are common in lower-temperature environments on the crater floor. Most chimneys show a high porosity, with a central conduit surrounded by an open and very permeable framework of sulfides and sulfates, aiding fluid flow through the chimney walls. In the sulfate-rich samples, blades of euhedral barite and anhydrite crystals coat the outside of the chimney wall, and layers of barite alternate with sulfide in the interior. The dominant sulfides are pyrite, sphalerite, wurtzite, marcasite and galena. Crusts on extinct and lower-temperature chimneys are composed of amorphous silica, goethite and halite. Sulfur isotope composition of sulfates is virtually at sea water values, whereas the sulfides are more depleted. Elevated levels of copper, gold and silver are observed in bulk composition of chimney samples. Both the structural setting, character of the vent field and sulfide/sulfate mineralogy and geochemistry indicate on-going Kuroko-type mineralization in the

  5. Hydrothermalism in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Dando, P. R.; Stüben, D.; Varnavas, S. P.

    1999-08-01

    Hydrothermalism in the Mediterranean Sea results from the collision of the African and European plates, with the subduction of the oceanic part of the African plate below Europe. High heat flows in the resulting volcanic arcs and back-arc extensional areas have set-up hydrothermal convection systems. Most of the known hydrothermal sites are in shallow coastal waters, <200 m depth, so that much of the reported fluid venting is of the gasohydrothermal type. The hydrothermal liquids are of varying salinities, both because of phase separation as a result of seawater boiling at the low pressures and because of significant inputs of rainfall into the hydrothermal reservoirs at some sites. The major component of the vented gas is carbon dioxide, with significant quantities of sulphur dioxide, hydrogen sulphide, methane and hydrogen also being released. Acid leaching of the underlying rocks leads to the mobilisation of heavy metals, many of which are deposited sub-surface although there is a conspicuous enrichment of metals in surficial sediments in venting areas. Massive polymetalic sulphides have been reported from some sites. No extant vent-specific fauna have been described from Mediterranean sites. There is a reduced diversity of fauna within the sediments at the vents. In contrast, a high diversity of epifauna has been reported and the vent sites are areas of settlement for exotic thermophilic species. Large numbers of novel prokaryotes, especially hyperthermophilic crenarchaeota, have been isolated from Mediterranean hydrothermal vents. However, their distribution in the subsurface biosphere and their role in the biogeochemistry of the sites has yet to be studied.

  6. Crustal magnetization and the subseafloor structure of the ASHES vent field, Axial Seamount, Juan de Fuca Ridge: Implications for the investigation of hydrothermal sites

    NASA Astrophysics Data System (ADS)

    Caratori Tontini, Fabio; Crone, Timothy J.; Ronde, Cornel E. J.; Fornari, Daniel J.; Kinsey, James C.; Mittelstaedt, Eric; Tivey, Maurice

    2016-06-01

    High-resolution geophysical data have been collected using the Autonomous Underwater Vehicle (AUV) Sentry over the ASHES (Axial Seamount Hydrothermal Emission Study) high-temperature (~348°C) vent field at Axial Seamount, on the Juan de Fuca Ridge. Multiple surveys were performed on a 3-D grid at different altitudes above the seafloor, providing an unprecedented view of magnetic data resolution as a function of altitude above the seafloor. Magnetic data derived near the seafloor show that the ASHES field is characterized by a zone of low magnetization, which can be explained by hydrothermal alteration of the host volcanic rocks. Surface manifestations of hydrothermal activity at the ASHES vent field are likely controlled by a combination of local faults and fractures and different lava morphologies near the seafloor. Three-dimensional inversion of the magnetic data provides evidence of a vertical, pipe-like upflow zone of the hydrothermal fluids with a vertical extent of ~100 m.

  7. Different TDM/CH4 hydrothermal plume signatures: TAG site at 26N and serpentinized ultrabasic diapir at 15 degrees 05'N on the Mid-Atlantic ridge

    SciTech Connect

    Charlou, J.L.; Bougault, H. ); Appriou, P. ); Nelsen, T.; Rona, P. )

    1991-11-01

    As a part of the 1988 NOAA VENTS Program, CH{sub 4} and Mn tracers were used to identify and compare hydrothermal plumes found above the TAG Field (26{degrees}N) and in the rift valley at 15{degrees}N close to the eastern intersection of the ridge axis with the 15{degrees}20'N Fracture Zone at the Mid-Atlantic Ridge (MAR). Active hydrothermal venting was confirmed at TAG, based on elevated concentrations of total dissolved Mn (TDM up to 30 nmol/kg), high CH{sub 4} concentrations (up to 200 nL/L), and elevated nephelometry signals. Plumes of a different composition were identified at 15{degree}N with high CH{sub 4} concentrations (up to 400 nL/L), low total dissolved Mn concentrations (TDM < 1 nmol/kg) and no significant nephelometry signal. The different properties of these tracers and the different tracer ratios can be used to deduce vent fluid characteristics and compare one hydrothermal area to another. TDM/CH{sub 4} and Nephel/CH{sub 4} ratios at TEG are of the same order of magnitude as those observed at other spreading axis hydrothermal fields. At 15{degrees}N, the low TDM/CH{sub 4} ratio provides evidence of fluid circulation into ultrabasic rocks and offers a potentially useful and single method of exploring for hydrothermal activity associated with serpentinization. Mantle degassing through hydrothermal activity associated with serpentinization is an important process with respect to chemical and thermal exchanges between the upper mantle and the ocean. Different ratios of hydrothermal tracers (i.e., TDM/CH{sub 4}) provide a useful framework for identifying subseafloor processes along mid-oceanic ridges.

  8. Hydrothermal Alteration of Glass from Underground Nuclear Tests: Formation and Transport of Pu-clay Colloids at the Nevada National Security Site

    SciTech Connect

    Zavarin, M.; Zhao, P.; Joseph, C.; Begg, J.; Boggs, M.; Dai, Z.; Kersting, A. B.

    2015-05-27

    The testing of nuclear weapons at the Nevada National Security Site (NNSS), formerly the Nevada Test Site (NTS), has led to the deposition of substantial quantities of plutonium into the environment. Approximately 2.8 metric tons (3.1×104 TBq) of Pu were deposited in the NNSS subsurface as a result of underground nuclear testing. While 3H is the most abundant anthropogenic radionuclide deposited in the NNSS subsurface (4.7×106 TBq), plutonium is the most abundant from a molar standpoint. The only radioactive elements in greater molar abundance are the naturally occurring K, Th, and U isotopes. 239Pu and 240Pu represent the majority of alpha-emitting Pu isotopes. The extreme temperatures associated with underground nuclear tests and the refractory nature of Pu results in most of the Pu (98%) being sequestered in melted rock, referred to as nuclear melt glass (Iaea, 1998). As a result, Pu release to groundwater is controlled, in large part, by the leaching (or dissolution) of nuclear melt glass over time. The factors affecting glass dissolution rates have been studied extensively. The dissolution of Pu-containing borosilicate nuclear waste glasses at 90ºC has been shown to lead to the formation of dioctahedral smectite colloids. Colloid-facilitated transport of Pu at the NNSS has been observed. Recent groundwater samples collected from a number of contaminated wells have yielded a wide range of Pu concentrations from 0.00022 to 2.0 Bq/L. While Pu concentrations tend to fall below the Maximum Contaminant Level (MCL) established by the Environmental Protection Agency (EPA) for drinking water (0.56 Bq/L), we do not yet understand what factors limit the Pu concentration or its transport behavior. To quantify the upper limit of Pu concentrations produced as a result of melt glass dissolution and determine the nature of colloids and Pu associations, we performed a 3 year nuclear melt glass dissolution experiment

  9. Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

    SciTech Connect

    Stein, J.S.; Fisher, A.T.; Langseth, M.; Jin, W.; Iturrino, G.; Davis, E.

    1998-12-01

    Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

  10. Trophic regions of a hydrothermal plume dispersing away from an ultramafic-hosted vent-system: Von Damm vent-site, Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Bennett, Sarah A.; Coleman, Max; Huber, Julie A.; Reddington, Emily; Kinsey, James C.; McIntyre, Cameron; Seewald, Jeffrey S.; German, Christopher R.

    2013-02-01

    Abstract Deep-sea ultramafic-hosted vent systems have the potential to provide large amounts of metabolic energy to both autotrophic and heterotrophic microorganisms in their dispersing <span class="hlt">hydrothermal</span> plumes. Such vent-systems release large quantities of hydrogen and methane to the water column, both of which can be exploited by autotrophic microorganisms. Carbon cycling in these <span class="hlt">hydrothermal</span> plumes may, therefore, have an important influence on open-ocean biogeochemistry. In this study, we investigated an ultramafic-hosted system on the Mid-Cayman Rise, emitting metal-poor and hydrogen sulfide-, methane-, and hydrogen-rich <span class="hlt">hydrothermal</span> fluids. Total organic carbon concentrations in the plume ranged between 42.1 and 51.1 μM (background = 43.2 ± 0.7 μM (n = 5)) and near-field plume samples with elevated methane concentrations imply the presence of chemoautotrophic primary production and in particular methanotrophy. In parts of the plume characterized by persistent potential temperature anomalies but lacking elevated methane concentrations, we found elevated organic carbon concentrations of up to 51.1 μM, most likely resulting from the presence of heterotrophic communities, their extracellular products and vent larvae. Elevated carbon concentrations up to 47.4 μM were detected even in far-field plume samples. Within the Von Damm <span class="hlt">hydrothermal</span> plume, we have used our data to hypothesize a microbial food web in which chemoautotrophy supports a heterotrophic community of microorganisms. Such an active microbial food web would provide a source of labile organic carbon to the deep ocean that should be considered in any future studies evaluating sources and sinks of carbon from <span class="hlt">hydrothermal</span> venting to the deep ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS51D1896R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS51D1896R"><span id="translatedtitle">Preliminary results from Submarine Ring of Fire 2012 - NE Lau: First explorations of <span class="hlt">hydrothermally</span> active volcanoes across the supra-subduction zone and a return to the West Mata eruption <span class="hlt">site</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Resing, J.; Embley, R. W.</p> <p>2012-12-01</p> <p>Several expeditions in the past few years have shown that the NE Lau basin has one of the densest concentrations of volcanically and <span class="hlt">hydrothermally</span> active volcanoes on the planet. In 2008 two active submarine volcanic eruptions were discovered during a one week period and subsequent dives with the Jason remotely operated vehicle at one of the <span class="hlt">sites</span> (West Mata) revealed an active boninite eruption taking place at 1200 m depth. Two dives at the other revealed evidence for recent eruption along the NE Lau Spreading Center. Several more expeditions in 2010-11 discovered additional evidence about the extent and types of <span class="hlt">hydrothermal</span> activity in this area. Data from CTDO (conductivity, temperature, depth, optical) vertical casts, tow-yos, and towed camera deployments revealed more than 15 <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> at water depths from ~800 to 2700 m that include <span class="hlt">sites</span> from the magmatic arc, the "rear arc," and the back arc spreading centers. These <span class="hlt">sites</span> range from high temperature black smoker sulfide-producing systems to those dominated by magmatic degassing. Dives by remotely operated vehicle (Quest 4000) in September 2012 will explore these <span class="hlt">sites</span> and return samples for chemical, biological and geologic studies. One of the dives will be a return visit to West Mata volcano, the <span class="hlt">site</span> of the deepest submarine eruption yet observed (in 2009). Recent multibeam data reveal large changes in West Mata's summit, suggesting that the nature of the eruption and the location of the erupting vents may have changed. In addition to the preliminary results from the science team, we will also discuss our use and experience with continuous live video transmission (through the High Definition video camera on the Quest 4000) back to shore via satellite and through the internet. Submarine Ring of Fire 2012 Science Team: Bradley Tebo, Bill Chadwick, Ed Baker, Ken Rubin, Susan Merle, Timothy Shank, Sharon Walker, Andra Bobbitt, Nathan Buck, David Butterfield, Eric Olson, John Lupton, Richard Arculus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14999274','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14999274"><span id="translatedtitle">Arctic Ocean: <span class="hlt">hydrothermal</span> activity on Gakkel Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jean-Baptiste, Philippe; Fourré, Elise</p> <p>2004-03-01</p> <p>In the <span class="hlt">hydrothermal</span> circulation at mid-ocean ridges, sea water penetrates the fractured crust, becomes heated by its proximity to the hot magma, and returns to the sea floor as hot fluids enriched in various chemical elements. In contradiction to earlier results that predict diminishing <span class="hlt">hydrothermal</span> activity with decreasing spreading rate, a survey of the ultra-slowly spreading Gakkel Ridge (Arctic Ocean) by Edmonds et al. and Michael et al. suggests that, instead of being rare, the <span class="hlt">hydrothermal</span> activity is abundant--exceeding by at least a factor of two to three what would be expected by extrapolation from observation on faster spreading ridges. Here we use helium-3 (3He), a <span class="hlt">hydrothermal</span> tracer, to show that this abundance of venting <span class="hlt">sites</span> does not translate, as would be expected, into an anomalous <span class="hlt">hydrothermal</span> 3He output from the ridge. Because of the wide implications of the submarine <span class="hlt">hydrothermal</span> processes for mantle heat and mass fluxes to the ocean, these conflicting results call for clarification of the link between <span class="hlt">hydrothermal</span> activity and crustal production at mid-ocean ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26684507','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26684507"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Conditions and the Origin of Cellular Life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deamer, David W; Georgiou, Christos D</p> <p>2015-12-01</p> <p>The conditions and properties of <span class="hlt">hydrothermal</span> vents and <span class="hlt">hydrothermal</span> fields are compared in terms of their ability to support processes related to the origin of life. The two <span class="hlt">sites</span> can be considered as alternative hypotheses, and from this comparison we propose a series of experimental tests to distinguish between them, focusing on those that involve concentration of solutes, self-assembly of membranous compartments, and synthesis of polymers. Key Word: <span class="hlt">Hydrothermal</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26684507','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26684507"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Conditions and the Origin of Cellular Life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deamer, David W; Georgiou, Christos D</p> <p>2015-12-01</p> <p>The conditions and properties of <span class="hlt">hydrothermal</span> vents and <span class="hlt">hydrothermal</span> fields are compared in terms of their ability to support processes related to the origin of life. The two <span class="hlt">sites</span> can be considered as alternative hypotheses, and from this comparison we propose a series of experimental tests to distinguish between them, focusing on those that involve concentration of solutes, self-assembly of membranous compartments, and synthesis of polymers. Key Word: <span class="hlt">Hydrothermal</span> systems. PMID:26684507</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930034010&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dorganic%2Bsynthesis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930034010&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dorganic%2Bsynthesis"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> organic synthesis experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, Everett L.</p> <p>1992-01-01</p> <p>Ways in which heat is useful in organic synthesis experiments are described, and experiments on the <span class="hlt">hydrothermal</span> destruction and synthesis of organic compounds are discussed. It is pointed out that, if heat can overcome kinetic barriers to the formation of metastable states from reduced or oxidized starting materials, abiotic synthesis under <span class="hlt">hydrothermal</span> conditions is a distinct possibility. However, carefully controlled experiments which replicate the descriptive variables of natural <span class="hlt">hydrothermal</span> systems have not yet been conducted with the aim of testing the hypothesis of <span class="hlt">hydrothermal</span> organic systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014620','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014620"><span id="translatedtitle">METEORIC-<span class="hlt">HYDROTHERMAL</span> SYSTEMS.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Criss, Robert E.; Taylor, Hugh P.</p> <p>1986-01-01</p> <p>This paper summarizes the salient characteristics of meteoric-<span class="hlt">hydrothermal</span> systems, emphasing the isotopic systematics. Discussions of permeable-medium fluid dynamics and the geology and geochemistry of modern geothermal systems are also provided, because they are essential to any understanding of <span class="hlt">hydrothermal</span> circulation. The main focus of the paper is on regions of ancient meteoric-<span class="hlt">hydrothermal</span> activity, which give us information about the presently inaccessible, deep-level parts of modern geothermal systems. It is shown oxygen and hydrogen isotopes provide a powerful method to discover and map fossil <span class="hlt">hydrothermal</span> systems and to investigate diverse associated aspects of rock alteration and ore deposition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GGG....15.3430D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GGG....15.3430D"><span id="translatedtitle">Insights into magmatic processes and <span class="hlt">hydrothermal</span> alteration of in situ superfast spreading ocean crust at ODP/IODP <span class="hlt">site</span> 1256 from a cluster analysis of rock magnetic properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dekkers, Mark J.; Heslop, David; Herrero-Bervera, Emilio; Acton, Gary; Krasa, David</p> <p>2014-08-01</p> <p>analyze magnetic properties from Ocean Drilling Program (ODP)/Integrated ODP (IODP) Hole 1256D (6°44.1' N, 91°56.1' W) on the Cocos Plate in ˜15.2 Ma oceanic crust generated by superfast seafloor spreading, the only drill hole that has sampled all three oceanic crust layers in a tectonically undisturbed setting. Fuzzy c-means cluster analysis and nonlinear mapping are utilized to study down-hole trends in the ratio of the saturation remanent magnetization and the saturation magnetization, the coercive force, the ratio of the remanent coercive force and coercive force, the low-field magnetic susceptibility, and the Curie temperature, to evaluate the effects of magmatic and <span class="hlt">hydrothermal</span> processes on magnetic properties. A statistically robust five cluster solution separates the data predominantly into three clusters that express increasing <span class="hlt">hydrothermal</span> alteration of the lavas, which differ from two distinct clusters mainly representing the dikes and gabbros. Extensive alteration can obliterate magnetic property differences between lavas, dikes, and gabbros. The imprint of thermochemical alteration on the iron-titanium oxides is only partially related to the porosity of the rocks. Thus, the analysis complements interpretation based on electrofacies analysis. All clusters display rock magnetic characteristics compatible with an ability to retain a stable natural remanent magnetization suggesting that the entire sampled sequence of ocean crust can contribute to marine magnetic anomalies. Paleointensity determination is difficult because of the propensity of oxyexsolution during laboratory heating and/or the presence of intergrowths. The upper part of the extrusive sequence, the granoblastic dikes, and moderately altered gabbros may contain a comparatively uncontaminated thermoremanent magnetization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.159...16W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.159...16W"><span id="translatedtitle">Distribution and solubility limits of trace elements in <span class="hlt">hydrothermal</span> black smoker sulfides: An in-situ LA-ICP-MS study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wohlgemuth-Ueberwasser, Cora C.; Viljoen, Fanus; Petersen, Sven; Vorster, Clarisa</p> <p>2015-06-01</p> <p>The key for understanding the trace metal inventory of currently explored VHMS deposits lies in the understanding of trace element distribution during the formation of these deposits on the seafloor. Recrystallization processes already occurring at the seafloor might liberate trace elements to later <span class="hlt">hydrothermal</span> alteration and removement. To investigate the distribution and redistribution of trace elements we analyzed sulfide minerals from 27 black smoker samples derived from three different seafloor <span class="hlt">hydrothermal</span> fields: the ultramafic-hosted <span class="hlt">Logatchev</span> <span class="hlt">hydrothermal</span> field on the Mid-Atlantic Ridge, the basaltic-hosted Turtle Pits field on the mid-atlantic ridge, and the felsic-hosted PACMANUS field in the Manus basin (Papua New Guinea). The sulfide samples were analyzed by mineral liberation analyser for the modal abundances of sulfide minerals, by electron microprobe for major elements and by laser ablation-inductively coupled plasma-mass spectrometry for As, Sb, Se, Te, and Au. The samples consist predominantly of chalcopyrite, sphalerite, pyrite, galena and minor isocubanite as well as inclusions of tetrahedrite-tennantite. Laser ablation spectra were used to evaluate the solubility limits of trace elements in different sulfide minerals at different textures. The solubility of As, Sb, and Au in pyrite decreases with increasing degree of recrystallization. When solubility limits are reached these elements occur as inclusions in the different sulfide phases or they are expelled from the mineral phase. Most ancient VHMS deposits represent felsic or bimodal felsic compositions. Samples from the felsic-hosted PACMANUS <span class="hlt">hydrothermal</span> field at the Pual ridge (Papua New Guinea) show high concentrations of Pb, As, Sb, Bi, Hg, and Te, which is likely the result of an additional trace element contribution derived from magmatic volatiles. Co-precipitating pyrite and chalcopyrite are characterized by equal contents of Te, while chalcopyrite that replaced pyrite (presumably</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010020499&hterms=pope&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpope','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010020499&hterms=pope&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpope"><span id="translatedtitle">Impact Crater <span class="hlt">Hydrothermal</span> Niches for Life on Mars: Question of Scale</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pope, K. O.; Ames, D. E.; Kieffer, S. W.; Ocampo, A. C.</p> <p>2000-01-01</p> <p>A major focus in the search for fossil life on Mars is on ancient <span class="hlt">hydrothermal</span> deposits. Nevertheless, remote sensing efforts have not found mineral assemblages characteristic of <span class="hlt">hydrothermal</span> activity. Future remote sensing work, including missions with higher spatial resolution, may detect localized <span class="hlt">hydrothermal</span> deposits, but it is possible that dust mantles will prohibit detection from orbit and lander missions will be required. In anticipation of such missions, it is critical to develop a strategy for selecting potential <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> on Mars. Such a strategy is being developed for volcanogenic <span class="hlt">hydrothermal</span> systems, and a similar strategy is needed for impact <span class="hlt">hydrothermal</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998E%26PSL.156..267G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998E%26PSL.156..267G"><span id="translatedtitle">Topographic control of a dispersing <span class="hlt">hydrothermal</span> plume</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>German, C. R.; Richards, K. J.; Rudnicki, M. D.; Lam, M. M.; Charlou, J. L.; Flame Scientific Party</p> <p>1998-03-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents represent a major source of heat and chemicals to the oceans and support endemic chemosynthetic biological communities. To fully understand the impact of <span class="hlt">hydrothermal</span> activity upon the oceans, however, requires investigation of both the physical and the biogeochemical processes which are active in <span class="hlt">hydrothermal</span> plumes and which serve to determine the net <span class="hlt">hydrothermal</span> flux to the oceans. We have recently conducted a detailed multidisciplinary study of the lateral dispersion of the <span class="hlt">hydrothermal</span> plume emitted from the Rainbow vent <span class="hlt">site</span> near 36°15'N, Mid-Atlantic Ridge. Combining velocity measurements from a lowered ADCP, optical back scatter measurements from a deep-tow CTD and methane measurements from bottle samples we are able, for the first time in the Atlantic, to trace a neutrally buoyant plume for a distance of over 50 km. The path of the plume is seen to be heavily controlled by the local topography with a general northeast movement of water. Both particle and methane concentrations decrease downstream over the length of the observed plume. The dataset provides an excellent opportunity to study the mixing and biogeochemical processes active in a <span class="hlt">hydrothermal</span> plume and estimate fluxes of biogeochemical constituents.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950057138&hterms=Hydrocyanic+acid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Hydrocyanic%2Bacid%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950057138&hterms=Hydrocyanic+acid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Hydrocyanic%2Bacid%2529"><span id="translatedtitle">Thermodynamics of Strecker synthesis in <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schulte, Mitchell; Shock, Everett</p> <p>1995-01-01</p> <p>Submarine <span class="hlt">hydrothermal</span> systems on the early Earth may have been the <span class="hlt">sites</span> from which life emerged. The potential for Strecker synthesis to produce biomolecules (amino and hydroxy acids) from starting compounds (ketones, aldehydes, HCN and ammonia) in such environments is evaluated quantitatively using thermodynamic data and parameters for the revised Helgeson-Kirkham-Flowers (HKF) equation of state. Although there is an overwhelming thermodynamic drive to form biomolecules by the Strecker synthesis at <span class="hlt">hydrothermal</span> conditions, the availability and concentration of starting compounds limit the efficiency and productivity of Strecker reactions. Mechanisms for concentrating reactant compounds could help overcome this problem, but other mechanisms for production of biomolecules may have been required to produce the required compounds on the early Earth. Geochemical constraints imposed by <span class="hlt">hydrothermal</span> systems provide important clues for determining the potential of these and other systems as <span class="hlt">sites</span> for the emergence of life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED477324.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED477324.pdf"><span id="translatedtitle">Living with the Heat. Submarine Ring of Fire--Grades 5-6. <span class="hlt">Hydrothermal</span> Vent Ecology.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>National Oceanic and Atmospheric Administration (DOC), Rockville, MD.</p> <p></p> <p>This activity is designed to teach about <span class="hlt">hydrothermal</span> vent ecology. Students are expected to describe how <span class="hlt">hydrothermal</span> vents are formed and characterize the physical conditions at these <span class="hlt">sites</span>, explain chemosynthesis and contrast this process with photosynthesis, identify autotrophic bacteria as the basis for food webs in <span class="hlt">hydrothermal</span> vent…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS24B..07T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS24B..07T"><span id="translatedtitle">Post-drilling <span class="hlt">hydrothermal</span> vent and associated biological activities seen through artificial <span class="hlt">hydrothermal</span> vents in the Iheya North field, Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takai, K.; Kawagucci, S.; Miyazaki, J.; Watsuji, T.; Ishibashi, J.; Yamamoto, H.; Nozaki, T.; Kashiwabara, T.; Shibuya, T.</p> <p>2012-12-01</p> <p>In 2010, IODP Expedition 331 was conducted in the Iheya North Field, the Okinawa Trough and drilled several <span class="hlt">sites</span> in <span class="hlt">hydrothermally</span> active subseafloor. In addition, during the IODP Expedition 331, four new <span class="hlt">hydrothermal</span> vents were created. These post-drilling artificial <span class="hlt">hydrothermal</span> vents provide excellent opportunities to investigate the physical, chemical and microbiological characteristics of the previously unexplored subseafloor <span class="hlt">hydrothermal</span> fluid reservoirs, and to monitor and estimate how the anthropogenic drilling behaviors affect the deep-sea <span class="hlt">hydrothermal</span> vent ecosystem. We were very much interested in the difference of <span class="hlt">hydrothermal</span> fluid chemistry between the natural <span class="hlt">hydrothermal</span> vents and the artificial <span class="hlt">hydrothermal</span> vents. The IODP porewater chemistry of the cores pointed to the density-driven stratification of the phase-separated <span class="hlt">hydrothermal</span> fluids and the natural vent fluids were likely derived only from the shallower vapor-enriched phases. However, the artificial <span class="hlt">hydrothermal</span> vents had deeper fluid sources in the subseafloor <span class="hlt">hydrothermal</span> fluid reservoirs composed of vapor-lost (Cl-enriched) phases. The fluids from the artificial <span class="hlt">hydrothermal</span> vents were sampled by ROV at 5, 12 and 18 months after the IODP expedition. The artificial <span class="hlt">hydrothermal</span> vent fluids were slightly enriched with Cl as compared to the natural <span class="hlt">hydrothermal</span> vent fluids. Thus, the artificial <span class="hlt">hydrothermal</span> vents successfully entrained the previously unexplored subseafloor <span class="hlt">hydrothermal</span> fluids. The newly created <span class="hlt">hydrothermal</span> vents also hosted the very quickly grown, enormous chimney structures, of which mineral compositions were highly variable among the vents. However, the quickly grown C0016B and C0016D vent chimneys were found to be typical Kuroko ore even though the chimney growth rates in the artificial vents were extremely faster than those in the natural vents. In addition, the IODP drilling operation not only created new <span class="hlt">hydrothermal</span> vents by deep drilling but also induced the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DSRI...55..203G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DSRI...55..203G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> exploration with the Autonomous Benthic Explorer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>German, Christopher R.; Yoerger, Dana R.; Jakuba, Michael; Shank, Timothy M.; Langmuir, Charles H.; Nakamura, Ko-ichi</p> <p></p> <p>We describe a three-phase use of the Woods Hole Oceanographic Institution's Autonomous Benthic Explorer ( ABE), to locate, map and photograph previously undiscovered fields of high temperature submarine <span class="hlt">hydrothermal</span> vents. Our approach represents both a complement to and a significant advance beyond the prior state of the art. Previously, <span class="hlt">hydrothermal</span> exploration relied upon deep-tow instruments equipped with sensors that could locate <span class="hlt">sites</span> of active "black smoker" venting to within a few kilometers. Follow-on CTD tow-yos could then resolve the <span class="hlt">sites</span> of seafloor venting to length scales of less than a kilometer but rarely to better than a few hundreds of meters. In our new approach ABE: (i) uses sensors to locate the center of a dispersing non-buoyant <span class="hlt">hydrothermal</span> plume 100-400 m above the seabed; (ii) makes high-resolution maps of the seafloor beneath the plume center whilst simultaneously detecting interception of any rising, buoyant <span class="hlt">hydrothermal</span> plumes; and (iii) dives to the seafloor to take photographs in and around any new vent <span class="hlt">site</span> to characterize its geologic setting and reveal the nature of any chemosynthetic ecosystems it may host. By conducting all of the above under long-baseline navigation, precise <span class="hlt">sites</span> of venting can be determined to within 5 m. Our approach can be used both to address important scientific issues in their own right and to ensure much more efficient use of other deep-submergence assets such as human occupied vehicles (HOVs) and remotely operated vehicles (ROVs) during follow-on studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1167674','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1167674"><span id="translatedtitle">Calibrated <span class="hlt">Hydrothermal</span> Parameters, Barrow, Alaska, 2013</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Atchley, Adam; Painter, Scott; Harp, Dylan; Coon, Ethan; Wilson, Cathy; Liljedahl, Anna; Romanovsky, Vladimir</p> <p>2015-01-29</p> <p>A model-observation-experiment process (ModEx) is used to generate three 1D models of characteristic micro-topographical land-formations, which are capable of simulating present active thaw layer (ALT) from current climate conditions. Each column was used in a coupled calibration to identify moss, peat and mineral soil <span class="hlt">hydrothermal</span> properties to be used in up-scaled simulations. Observational soil temperature data from a tundra <span class="hlt">site</span> located near Barrow, AK (Area C) is used to calibrate thermal properties of moss, peat, and sandy loam soil to be used in the multiphysics Advanced Terrestrial Simulator (ATS) models. Simulation results are a list of calibrated <span class="hlt">hydrothermal</span> parameters for moss, peat, and mineral soil <span class="hlt">hydrothermal</span> parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080010733','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080010733"><span id="translatedtitle">Ancient <span class="hlt">Hydrothermal</span> Springs in Arabia Terra, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oehler, Dorothy Z.; Allen, Carlton C.</p> <p>2008-01-01</p> <p><span class="hlt">Hydrothermal</span> springs are important astrobiological <span class="hlt">sites</span> for several reasons: 1) On Earth, molecular phylogeny suggests that many of the most primitive organisms are hyperthermophiles, implying that life on this planet may have arisen in <span class="hlt">hydrothermal</span> settings; 2) on Mars, similar settings would have supplied energy- and nutrient-rich waters in which early martian life may have evolved; 3) such regions on Mars would have constituted oases of continued habitability providing warm, liquid water to primitive life forms as the planet became colder and drier; and 4) mineralization associated with <span class="hlt">hydrothermal</span> settings could have preserved biosignatures from those martian life forms. Accordingly, if life ever developed on Mars, then <span class="hlt">hydrothermal</span> spring deposits would be excellent localities in which to search for morphological or chemical remnants of that life. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel which allows detailed analysis of geologic structure and geomorphology. Based on these new data, we report several features in Vernal Crater, Arabia Terra that we interpret as ancient <span class="hlt">hydrothermal</span> springs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1203906','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1203906"><span id="translatedtitle">Catalytic <span class="hlt">Hydrothermal</span> Gasification</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Elliott, Douglas C.</p> <p>2015-05-31</p> <p>The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical <span class="hlt">hydrothermal</span> processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. <span class="hlt">Hydrothermal</span> gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the <span class="hlt">hydrothermal</span> liquefaction mechanisms that begin at the lowest <span class="hlt">hydrothermal</span> conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, <span class="hlt">hydrothermal</span> gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984ESRv...20....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984ESRv...20....1R"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> mineralization at seafloor spreading centers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rona, Peter A.</p> <p>1984-01-01</p> <p>The recent recognition that metallic mineral deposits are concentrated by <span class="hlt">hydrothermal</span> processes at seafloor spreading centers constitutes a scientific breakthrough that opens active <span class="hlt">sites</span> at seafloor spreading centers as natural laboratories to investigate ore-forming processes of such economically useful deposits as massive sulfides in volcanogenic rocks on land, and that enhances the metallic mineral potential of oceanic crust covering two-thirds of the Earth both beneath ocean basins and exposed on land in ophiolite belts. This paper reviews our knowledge of processes of <span class="hlt">hydrothermal</span> mineralization and the occurrence and distribution of <span class="hlt">hydrothermal</span> mineral deposits at the global oceanic ridge-rift system. Sub-seafloor <span class="hlt">hydrothermal</span> convection involving circulation of seawater through fractured rocks of oceanic crust driven by heat supplied by generation of new lithosphere is nearly ubiquitous at seafloor spreading centers. However, ore-forming <span class="hlt">hydrothermal</span> systems are extremely localized where conditions of anomalously high thermal gradients and permeability increase <span class="hlt">hydrothermal</span> activity from the ubiquitous low-intensity background level (⩽ 200°C) to high-intensity characterized by high temperatures ( > 200-c.400°C), and a rate and volume of flow sufficient to sustain chemical reactions that produce acid, reducing, metal-rich primary <span class="hlt">hydrothermal</span> solutions. A series of mineral phases with sulfides and oxides as high- and low-temperature end members, respectively, are precipitated along the upwelling limb and in the discharge zone of single-phase systems as a function of increasing admixture of normal seawater. The occurrence of <span class="hlt">hydrothermal</span> mineral deposits is considered in terms of spatial and temporal frames of reference. Spatial frames of reference comprise structural features along-axis (linear sections that are the loci of seafloor spreading alternating with transform faults) and perpendicular to axis (axial zone of volcanic extrusion and marginal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1984ESRv...20....1R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1984ESRv...20....1R&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> mineralization at seafloor spreading centers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rona, Peter A.</p> <p>1984-01-01</p> <p>The recent recognition that metallic mineral deposits are concentrated by <span class="hlt">hydrothermal</span> processes at seafloor spreading centers constitutes a scientific breakthrough that opens active <span class="hlt">sites</span> at seafloor spreading centers as natural laboratories to investigate ore-forming processes of such economically useful deposits as massive sulfides in volcanogenic rocks on land, and that enhances the metallic mineral potential of oceanic crust covering two-thirds of the Earth both beneath ocean basins and exposed on land in ophiolite belts. This paper reviews our knowledge of processes of <span class="hlt">hydrothermal</span> mineralization and the occurrence and distribution of <span class="hlt">hydrothermal</span> mineral deposits at the global oceanic ridge-rift system. Sub-seafloor <span class="hlt">hydrothermal</span> convection involving circulation of seawater through fractured rocks of oceanic crust driven by heat supplied by generation of new lithosphere is nearly ubiquitous at seafloor spreading centers. However, ore-forming <span class="hlt">hydrothermal</span> systems are extremely localized where conditions of anomalously high thermal gradients and permeability increase <span class="hlt">hydrothermal</span> activity from the ubiquitous low-intensity background level (⩽ 200°C) to high-intensity characterized by high temperatures ( > 200-c.400°C), and a rate and volume of flow sufficient to sustain chemical reactions that produce acid, reducing, metal-rich primary <span class="hlt">hydrothermal</span> solutions. A series of mineral phases with sulfides and oxides as high- and low-temperature end members, respectively, are precipitated along the upwelling limb and in the discharge zone of single-phase systems as a function of increasing admixture of normal seawater. The occurrence of <span class="hlt">hydrothermal</span> mineral deposits is considered in terms of spatial and temporal frames of reference. Spatial frames of reference comprise structural features along-axis (linear sections that are the loci of seafloor spreading alternating with transform faults) and perpendicular to axis (axial zone of volcanic extrusion and marginal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.minsocam.org/MSA/AmMin/TOC/2016/index.html?issue_number=02','USGSPUBS'); return false;" href="http://www.minsocam.org/MSA/AmMin/TOC/2016/index.html?issue_number=02"><span id="translatedtitle">The Lassen <span class="hlt">hydrothermal</span> system</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ingebritsen, Steven E.; Bergfeld, Deborah; Clor, Laura; Evans, William C.</p> <p>2016-01-01</p> <p>The active Lassen <span class="hlt">hydrothermal</span> system includes a central vapor-dominated zone or zones beneath the Lassen highlands underlain by ~240 °C high-chloride waters that discharge at lower elevations. It is the best-exposed and largest <span class="hlt">hydrothermal</span> system in the Cascade Range, discharging 41 ± 10 kg/s of steam (~115 MW) and 23 ± 2 kg/s of high-chloride waters (~27 MW). The Lassen system accounts for a full 1/3 of the total high-temperature <span class="hlt">hydrothermal</span> heat discharge in the U.S. Cascades (140/400 MW). <span class="hlt">Hydrothermal</span> heat discharge of ~140 MW can be supported by crystallization and cooling of silicic magma at a rate of ~2400 km3/Ma, and the ongoing rates of heat and magmatic CO2 discharge are broadly consistent with a petrologic model for basalt-driven magmatic evolution. The clustering of observed seismicity at ~4–5 km depth may define zones of thermal cracking where the <span class="hlt">hydrothermal</span> system mines heat from near-plastic rock. If so, the combined areal extent of the primary heat-transfer zones is ~5 km2, the average conductive heat flux over that area is >25 W/m2, and the conductive-boundary length <50 m. Observational records of <span class="hlt">hydrothermal</span> discharge are likely too short to document long-term transients, whether they are intrinsic to the system or owe to various geologic events such as the eruption of Lassen Peak at 27 ka, deglaciation beginning ~18 ka, the eruptions of Chaos Crags at 1.1 ka, or the minor 1914–1917 eruption at the summit of Lassen Peak. However, there is a rich record of intermittent <span class="hlt">hydrothermal</span> measurement over the past several decades and more-frequent measurement 2009–present. These data reveal sensitivity to climate and weather conditions, seasonal variability that owes to interaction with the shallow hydrologic system, and a transient 1.5- to twofold increase in high-chloride discharge in response to an earthquake swarm in mid-November 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19159423','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19159423"><span id="translatedtitle">Comparison of microbial communities associated with phase-separation-induced <span class="hlt">hydrothermal</span> fluids at the Yonaguni Knoll IV <span class="hlt">hydrothermal</span> field, the Southern Okinawa Trough.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nunoura, Takuro; Takai, Ken</p> <p>2009-03-01</p> <p>Microbial communities associated with a variety of <span class="hlt">hydrothermal</span> emissions at the Yonaguni Knoll IV <span class="hlt">hydrothermal</span> field, the southernmost Okinawa Trough, were analyzed by culture-dependent and -independent techniques. In this <span class="hlt">hydrothermal</span> field, dozens of vent <span class="hlt">sites</span> hosting physically and chemically distinct <span class="hlt">hydrothermal</span> fluids were observed. Variability in the gas content and formation in the <span class="hlt">hydrothermal</span> fluids was observed and could be controlled by the potential subseafloor phase-separation and -partition processes. The hydrogen concentration in the <span class="hlt">hydrothermal</span> fluids was also variable (0.8-3.6 mmol kg(-1)) among the chimney <span class="hlt">sites</span>, but was unusually high as compared with those in other Okinawa Trough <span class="hlt">hydrothermal</span> fields. Despite the physical and chemical variabilities of the <span class="hlt">hydrothermal</span> fluids, the microbial communities were relatively similar among the habitats. Based on both culture-dependent and -independent analyses of the microbial community structures, members of Thermococcales, Methanococcales and Desulfurococcales likely represent the predominant archaeal components, while members of Nautiliaceae and Thioreductoraceae are considered to dominate the bacterial population. Most of the abundant microbial components appear to be chemolithotrophs sustained by hydrogen oxidation. The relatively consistent microbial communities found in this study could have been because of the sufficient input of hydrogen from the <span class="hlt">hydrothermal</span> fluids rather than other chemical properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012024','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012024"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> reactivity of saponite.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Whitney, G.</p> <p>1983-01-01</p> <p>The nature and extent of the reactions of synthetic Fe-free saponite have been investigated under experimental <span class="hlt">hydrothermal</span> conditions as a first step towards understanding saponite reactivity under relatively simple conditions. Saponite crystallizes from amorphous gel of ideal saponite composition within 7 days at 300o-550oC under P = 1 kbar. Reactions subsequent to this initial crystallization depend on reaction T and interlayer cations. Saponite is found to react <span class="hlt">hydrothermally</span>, over a period of 200 days, at T down to 400oC, at least 150oC lower than previously reported, but showed no signs of reaction below 400oC. At 450oC, a mixture of talc/saponite and saponite/phlogopite clays forms from K-saponite via intracrystalline layer transformations, while above 450oC the initial K-saponite dissolves, with talc and phlogopite forming as discrete phases. After 200 days reactions at 400-450oC were not complete, so that given sufficient time to reach equilibrium, a lower <span class="hlt">hydrothermal</span> stability limit for saponite is possible. Further study of the Fe-bearing saponite system will be required before experimental results can be applied to natural systems.-D.F.B.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DSRII.121....8H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DSRII.121....8H"><span id="translatedtitle">The Trans-Atlantic Geotraverse <span class="hlt">hydrothermal</span> field: A <span class="hlt">hydrothermal</span> system on an active detachment fault</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Humphris, Susan E.; Tivey, Margaret K.; Tivey, Maurice A.</p> <p>2015-11-01</p> <p>Over the last ten years, geophysical studies have revealed that the Trans-Atlantic Geotraverse (TAG) <span class="hlt">hydrothermal</span> field (26°08‧N on the Mid-Atlantic Ridge) is located on the hanging wall of an active detachment fault. This is particularly important in light of the recognition that detachment faulting accounts for crustal accretion/extension along a significant portion of the Mid-Atlantic Ridge, and that the majority of confirmed vent <span class="hlt">sites</span> on this slow-spreading ridge are hosted on detachment faults. The TAG <span class="hlt">hydrothermal</span> field is one of the largest <span class="hlt">sites</span> of high-temperature <span class="hlt">hydrothermal</span> activity and mineralization found to date on the seafloor, and is comprised of active and relict deposits in different stages of evolution. The episodic nature of <span class="hlt">hydrothermal</span> activity over the last 140 ka provides strong evidence that the complex shape and geological structure of the active detachment fault system exerts first order, but poorly understood, influences on the <span class="hlt">hydrothermal</span> circulation patterns, fluid chemistry, and mineral deposition. While <span class="hlt">hydrothermal</span> circulation extracts heat from a deep source region, the location of the source region at TAG is unknown. <span class="hlt">Hydrothermal</span> upflow is likely focused along the relatively permeable detachment fault interface at depth, and then the high temperature fluids leave the low-angle portion of the detachment fault and rise vertically through the highly fissured hanging wall to the seafloor. The presence of abundant anhydrite in the cone on the summit of the TAG active mound and in veins in the crust beneath provides evidence for a fluid circulation system that entrains significant amounts of seawater into the shallow parts of the mound and stockwork. Given the importance of detachment faulting for crustal extension at slow spreading ridges, the fundamental question that still needs to be addressed is: How do detachment fault systems, and the structure at depth associated with these systems (e.g., presence of plutons and/or high</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS22A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS22A..07S"><span id="translatedtitle">Microbiological production and ecological flux of northwestern subduction <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sunamura, M.; Okamura, K.; Noguchi, T.; Yamamoto, H.; Fukuba, T.; Yanagawa, K.</p> <p>2012-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> system is one of the most important sources for heat and chemical flux from the oceanic crust to the global ocean. The rich biological community around the <span class="hlt">hydrothermal</span> vent shows chemolithoautotrophic microbial production are important in deep sea ecosystems. More than 99% of microbiological available chemical components in <span class="hlt">hydrothermal</span> vent fluid, e.g. sulfide, methane, hydrogen, Fe2+, and Mn2+, is released into surrounding seawater to construct <span class="hlt">hydrothermal</span> plume, suggesting that the chemolithoautotrophic-microbial primary production in the <span class="hlt">hydrothermal</span> plume is huge and important in the whole <span class="hlt">hydrothermal</span> ecosystems. To understand the impact of <span class="hlt">hydrothermal</span> plume to a microbial ecosystem and a connectivity with zooplankton, we targeted and investigated a total of 16 <span class="hlt">hydrothermal</span> fileds (7 <span class="hlt">sites</span> in Okinawa trough, 3 <span class="hlt">sites</span> in Ogasawara arc, and 6 <span class="hlt">sites</span> in Mariana arc and back arc) and investigated in several cruises under the TAIGA project in Japan. <span class="hlt">Hydrothermal</span> fluids in the subduction system are rich in sulfide. The <span class="hlt">hydrothermal</span> fluids in the Okinawa trough, Ogasawara arc. and Mariana trough are characterized by rich in methane, poor in other reduced chemicals, and rich in iron, respectively. The major microbial composition was a potential sulfur oxidizing microbes SUP05 in the plume ecosystems, while an aerobic methanotrophic bacteria was secondary major member in methane-rich <span class="hlt">hydrothermal</span> systems in Okinawa trough. Microbial quantitative and spatial distribution analyses of each plume <span class="hlt">site</span> showed that the microbial population size and community structures are influenced by original chemical components of <span class="hlt">hydrothermal</span> fluid, e.g. sulfide, methane and iron concentration. Microbial quantitative data indicated the removal/sedimentation of microbial cells from the plume and effect of phase separation in a same vent field through construction of gas-rich or gas-poor plumes. After the correlation of plume mixing effect, we estimates that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7049433','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7049433"><span id="translatedtitle">Active and relict sea-floor <span class="hlt">hydrothermal</span> mineralization at the TAG <span class="hlt">hydrothermal</span> field, Mid-Atlantic Ridge</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rona, P.A. . Atlantic Oceanographic and Meteorological Labs.); Hannington, M.D. ); Raman, C.V. ); Thompson, G.; Tivey, M.K.; Humphris, S.E. ); Lalou, C. . Lab. CNRS-CEA); Petersen, S. Aachen Univ. of Technology )</p> <p>1993-12-01</p> <p>The TAG <span class="hlt">hydrothermal</span> field is a <span class="hlt">site</span> of major active and inactive volcanic-hosted <span class="hlt">hydrothermal</span> mineralization in the rift valley of the slow-spreading Mid-Atlantic Ridge at 26[degree]N. The axial high is the principal locus of present magmatic intrusions. The TAG field contains three main areas of present and past <span class="hlt">hydrothermal</span> activity: (1) an actively venting high-temperature sulfide mound; (2) two former high-temperature vent areas; (3) a zone of low-temperature venting and precipitation of Fe and Mn oxide deposits. The volcanic centers occur at the intersections between ridge axis-parallel normal faults and projected axis-transverse transfer faults. The intersections of these active fault systems may act as conduits both for magmatic intrusions from sources beneath the axial high that build the volcanic centers and for <span class="hlt">hydrothermal</span> upwelling that taps the heat sources. Radiometric dating of sulfide samples and manganese crusts in the <span class="hlt">hydrothermal</span> zones and dating of sediments intercalated with pillow lava flows in the volcanic center adjacent to the active sulfide mound indicate multiple episodes of <span class="hlt">hydrothermal</span> activity throughout the field driven by heat supplied by episodic intrusions over a period of at least 140 [times] 10[sup 3] yr. The sulfide deposits are built by juxtaposition and superposition during relatively long residence times near episodic axial heat sources counterbalanced by mass wasting in the tectonically active rift valley of the slow-spreading oceanic ridge. <span class="hlt">Hydrothermal</span> reworking of a relict <span class="hlt">hydrothermal</span> zone by high-temperature <span class="hlt">hydrothermal</span> episodes has recrystallized sulfides and concentrated the first visible primary gold reported in a deposit at an oceanic ridge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1032423','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1032423"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Liquefaction of Biomass</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Elliott, Douglas C.</p> <p>2010-12-10</p> <p><span class="hlt">Hydrothermal</span> liquefaction technology is describes in its relationship to fast pyrolysis of biomass. The scope of work at PNNL is discussed and some intial results are presented. <span class="hlt">HydroThermal</span> Liquefaction (HTL), called high-pressure liquefaction in earlier years, is an alternative process for conversion of biomass into liquid products. Some experts consider it to be pyrolysis in solvent phase. It is typically performed at about 350 C and 200 atm pressure such that the water carrier for biomass slurry is maintained in a liquid phase, i.e. below super-critical conditions. In some applications catalysts and/or reducing gases have been added to the system with the expectation of producing higher yields of higher quality products. Slurry agents ('carriers') evaluated have included water, various hydrocarbon oils and recycled bio-oil. High-pressure pumping of biomass slurry has been a major limitation in the process development. Process research in this field faded away in the 1990s except for the <span class="hlt">HydroThermal</span> Upgrading (HTU) effort in the Netherlands, but has new resurgence with other renewable fuels in light of the increased oil prices and climate change concerns. Research restarted at Pacific Northwest National Laboratory (PNNL) in 2007 with a project, '<span class="hlt">HydroThermal</span> Liquefaction of Agricultural and Biorefinery Residues' with partners Archer-Daniels-Midland Company and ConocoPhillips. Through bench-scale experimentation in a continuous-flow system this project investigated the bio-oil yield and quality that could be achieved from a range of biomass feedstocks and derivatives. The project was completed earlier this year with the issuance of the final report. <span class="hlt">HydroThermal</span> Liquefaction research continues within the National Advanced Biofuels Consortium with the effort focused at PNNL. The bench-scale reactor is being used for conversion of lignocellulosic biomass including pine forest residue and corn stover. A complementary project is an international collaboration with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.P31G..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P31G..02R"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Occurrences in Gusev Crater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruff, S. W.; Farmer, J. D.; Milliken, R.; Mills, V. W.; Shock, E.</p> <p>2011-12-01</p> <p>Exploration of the Gusev crater landing <span class="hlt">site</span> by the Spirit rover has revealed for the first time, in situ evidence of <span class="hlt">hydrothermal</span> activity on Mars. Most compelling are eroded outcrops of opaline silica found adjacent to "Home Plate" [1], an eroded stack of volcaniclastic deposits stratigraphically overlain by a vesicular basalt unit [2]. Recent work [3] demonstrates that the silica outcrops occur in a stratiform unit that possibly surrounds Home Plate. The outcrops are dominated by opal-A with no evidence for diagenesis to other silica phases. No other hydrous or alteration phases have been identified within the outcrops; most notable is a lack of sulfur phases. The outcrops have porous and in some cases, brecciated microtextures. Taken together, these observations support the interpretation that the opaline silica outcrops were produced in a hot spring or perhaps geyser environment. In this context, they are silica sinter deposits precipitated from silica-rich <span class="hlt">hydrothermal</span> fluids, possibly related to the volcanism that produced the Home Plate volcanic rocks. On Earth, debris aprons in which sinter is brecciated, reworked, and cemented, are common features of hot springs and geysers and are good analogs for the Martian deposits. An alternative hypothesis is that the silica resulted from acid-sulfate leaching of precursor rocks by fumarolic steam condensates. But stratigraphic, textural, and chemical observations tend to diminish this possibility [3]. We are conducting extensive laboratory and field investigations of silica from both hot spring/geyser and fumarole environments to understand the full range of mineralogical, chemical, textural, and morphological variations that accompany its production, in order to shed more light on the Home Plate occurrence. The recent discovery of abundant Mg-Fe carbonate (16-34 wt%) in outcrops named Comanche provides possible evidence for additional <span class="hlt">hydrothermal</span> activity in Gusev [4]. However, the carbonate is hosted by olivine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20150006657&hterms=thermohaline+circulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2528thermohaline%2Bcirculation%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20150006657&hterms=thermohaline+circulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2528thermohaline%2Bcirculation%2529"><span id="translatedtitle">Enceladus: Starting <span class="hlt">Hydrothermal</span> Activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.</p> <p>2011-01-01</p> <p>We describe a process for starting the <span class="hlt">hydrothermal</span> activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7075154','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7075154"><span id="translatedtitle">Cody <span class="hlt">hydrothermal</span> system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heasler, H.P.</p> <p>1982-01-01</p> <p>The hot springs of Colter's Hell are the surface manifestations of a much larger hydothermal system. That system has been studied to define its extent, maximum temperature, and mechanism of operation. The study area covers 2700 km/sup 2/ (1040 mi/sup 2/) in northwest Wyoming. Research and field work included locating and sampling the hot springs, geologic mapping, thermal logging of available wells, measuring thermal conductivities, analyzing over 200 oil and gas well bottom-hole temperatures, and compiling and analyzing hydrologic data. These data were used to generate a model for the <span class="hlt">hydrothermal</span> system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.V54A..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V54A..04D"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Mineralization Along the Volcanically Active Mariana Arc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Ronde, C. E.; Hein, J. R.; Embley, R. W.; Stern, R. J.</p> <p>2004-12-01</p> <p>In March and April, 2004, ROPOS ROV dives took place from the R/V T.G. Thompson along the volcanically active Mariana arc to ground truth CTD data collected a year earlier that indicated <span class="hlt">hydrothermal</span> activity. Dives took place on seven volcanoes, six of which showed <span class="hlt">hydrothermal</span> activity. We present data on samples collected from NW Rota-1 (14° , 36'N, 144° , 46'E), E. Diamante (15° , 56'N, 145° , 41'E), and NW Eifuku (21° , 29'N, 144° , 03'E), the three <span class="hlt">sites</span> most studied. All the <span class="hlt">hydrothermal</span> systems found are associated with volcano summits, or with resurgent domes inside a caldera. Brimstone vent at NW Rota-1 provided a dramatic display of thick, bellowing, yellow plumes that contained ash and molten sulfur. This <span class="hlt">site</span> occurs at 500 m water depth and clearly shows closely associated magmatic-<span class="hlt">hydrothermal</span> discharge. Sulfur was the dominant <span class="hlt">hydrothermal</span> mineral deposited around the vent and occurs as spheres in the surrounding volcaniclastic sediment, fracture fill and veins, and massive deposits. The Black Forest vent field at E Diamante consists of a sulfide-sulfate chimney system developed at about 650 m water depth. This is the only mature system discovered and consists of numerous tall (up to 9 m) chimneys. The measured fluid temperature of 240° C produces boiling at the depth of the vents. The chimneys and mounds are composed of varying amounts of pyrite, sphalerite, chalcopyrite, barite, and anhydrite. <span class="hlt">Hydrothermal</span> Mn oxides occur on the surface of inactive chimneys. This mineralogy contrasts with the other two systems, which deposit sulfur as the dominant <span class="hlt">hydrothermal</span> product. The Cu-Zn-Fe-Ba mineralization is perhaps largely controlled by water/rock interaction. A unique <span class="hlt">hydrothermal</span> field (Champagne field) was found at NW Eifuku where liquid CO2 is discharging from focused- and diffuse-flow vents at 1600 m water depth. The focused-flow vents consist of small chimneys and mounds up to a meter high that are composed of sulfur and yet to be</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008epsc.conf..900P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008epsc.conf..900P"><span id="translatedtitle">Targeting organic molecules in <span class="hlt">hydrothermal</span> environments on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parnell, J.; Bowden, S. A.; Lindgren, P.; Wilson, R.; Cooper, J. M.</p> <p>2008-09-01</p> <p><span class="hlt">Hydrothermal</span> deposits on Mars <span class="hlt">Hydrothermal</span> systems are proposed as environments that could support organic synthesis, the evolution of life or the maintenance of life [1,2,3]. They have therefore been suggested as primary targets for exploration on Mars [1,2,4,].There is now confidence that <span class="hlt">hydrothermal</span> deposits occur at the martian surface. This is based on a range of criteria that could point towards <span class="hlt">hydrothermal</span> activity, including volcanic activity, magmatic-driven tectonism, impact cratering in icy terrains, hydrous alteration of minerals and typical <span class="hlt">hydrothermal</span> mineralogies [4]. The proposals to search for evidence of life at martian <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> have been focussed on seeking morphological evidence of microbial activity [5]. Here we discuss the potential to seek a chemical signature of organic matter in <span class="hlt">hydrothermal</span> systems. Organics in terrestrial <span class="hlt">hydrothermal</span> systems Terrestrial <span class="hlt">hydrothermal</span> systems can have large quantities of organic matter because they intersect organic-rich sedimentary rocks or oil reservoirs. Thus the signatures that they contain reflect some preexisting concentration of fossil organic compounds, rather than life which was active in the <span class="hlt">hydrothermal</span> system. If any extant life was incorporated in these <span class="hlt">hydrothermal</span> systems, it is swamped by the fossil molecules. Examples of environments where organic materials may become entrained include subsurface <span class="hlt">hydrothermal</span> mineral deposits, generation of <span class="hlt">hydrothermal</span> systems by igneous intrusions, and hot fluid venting at the seafloor. Nevertheless, there is value in studying the interactions of <span class="hlt">hydrothermal</span> systems with fossil organic matter, for information about the survivability of organic compounds, phase relationships between carbonaceous and noncarbonaceous materials, and where in <span class="hlt">hydrothermal</span> deposits to find evidence of organic matter. Microbial colonization of hot spring systems is feasible at depth within the systems and at the surface where the <span class="hlt">hydrothermal</span> waters discharge</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21707671','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21707671"><span id="translatedtitle">Comparison of microbial communities associated with three Atlantic ultramafic <span class="hlt">hydrothermal</span> systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roussel, Erwan G; Konn, Cécile; Charlou, Jean-Luc; Donval, Jean-Pierre; Fouquet, Yves; Querellou, Joël; Prieur, Daniel; Bonavita, Marie-Anne Cambon</p> <p>2011-09-01</p> <p>The distribution of Archaea and methanogenic, methanotrophic and sulfate-reducing communities in three Atlantic ultramafic-hosted <span class="hlt">hydrothermal</span> systems (Rainbow, Ashadze, Lost City) was compared using 16S rRNA gene and functional gene (mcrA, pmoA and dsrA) clone libraries. The overall archaeal community was diverse and heterogeneously distributed between the <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> and the types of samples analyzed (seawater, <span class="hlt">hydrothermal</span> fluid, chimney and sediment). The Lost City <span class="hlt">hydrothermal</span> field, characterized by high alkaline warm fluids (pH>11; T<95 °C), harbored a singular archaeal diversity mostly composed of unaffiliated Methanosarcinales. The archaeal communities associated with the recently discovered Ashadze 1 <span class="hlt">site</span>, one of the deepest active <span class="hlt">hydrothermal</span> fields known (4100 m depth), showed significant differences between the two different vents analyzed and were characterized by putative extreme halophiles. Sequences related to the rarely detected Nanoarchaeota phylum and Methanopyrales order were also retrieved from the Rainbow and Ashadze <span class="hlt">hydrothermal</span> fluids. However, the methanogenic Methanococcales was the most widely distributed hyper/thermophilic archaeal group among the hot and acidic ultramafic-hosted <span class="hlt">hydrothermal</span> system environments. Most of the lineages detected are linked to methane and hydrogen cycling, suggesting that in ultramafic-hosted <span class="hlt">hydrothermal</span> systems, large methanogenic and methanotrophic communities could be fuelled by <span class="hlt">hydrothermal</span> fluids highly enriched in methane and hydrogen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034150','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034150"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> processes above the Yellowstone magma chamber: Large <span class="hlt">hydrothermal</span> systems and large <span class="hlt">hydrothermal</span> explosions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, L.A.; Shanks, W.C. Pat; Pierce, K.L.</p> <p>2009-01-01</p> <p><span class="hlt">Hydrothermal</span> explosions are violent and dramatic events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments from source craters that range from a few meters up to more than 2 km in diameter; associated breccia can be emplaced as much as 3 to 4 km from the largest craters. <span class="hlt">Hydrothermal</span> explosions occur where shallow interconnected reservoirs of steam- and liquid-saturated fluids with temperatures at or near the boiling curve underlie thermal fields. Sudden reduction in confi ning pressure causes fluids to fl ash to steam, resulting in signifi cant expansion, rock fragmentation, and debris ejection. In Yellowstone, <span class="hlt">hydrothermal</span> explosions are a potentially signifi cant hazard for visitors and facilities and can damage or even destroy thermal features. The breccia deposits and associated craters formed from <span class="hlt">hydrothermal</span> explosions are mapped as mostly Holocene (the Mary Bay deposit is older) units throughout Yellowstone National Park (YNP) and are spatially related to within the 0.64-Ma Yellowstone caldera and along the active Norris-Mammoth tectonic corridor. In Yellowstone, at least 20 large (>100 m in diameter) <span class="hlt">hydrothermal</span> explosion craters have been identifi ed; the scale of the individual associated events dwarfs similar features in geothermal areas elsewhere in the world. Large <span class="hlt">hydrothermal</span> explosions in Yellowstone have occurred over the past 16 ka averaging ??1 every 700 yr; similar events are likely in the future. Our studies of large <span class="hlt">hydrothermal</span> explosion events indicate: (1) none are directly associated with eruptive volcanic or shallow intrusive events; (2) several historical explosions have been triggered by seismic events; (3) lithic clasts and comingled matrix material that form <span class="hlt">hydrothermal</span> explosion deposits are extensively altered, indicating that explosions occur in areas subjected to intense <span class="hlt">hydrothermal</span> processes; (4) many lithic clasts contained in explosion breccia deposits preserve evidence of repeated fracturing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13A1700I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1700I"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> fluid-mineral interactions within volcanic sediment layer revealed by shallow drilling in active seafloor <span class="hlt">hydrothermal</span> fields in the mid-Okinawa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishibashi, J.; Miyoshi, Y.; Tanaka, K.; Omori, E.; Takahashi, Y.; Furuzawa, Y.; Yamanaka, T.; Kawagucci, S.; Yoshizumi, R.; Urabe, T.</p> <p>2012-12-01</p> <p>TAIGA11 Expedition of R/V Hakurei-maru No.2 was conducted in June, 2011 to study subseafloor environment below active <span class="hlt">hydrothermal</span> fields using a shallow drilling system (called as Benthic Multi-coring System, BMS). Three active <span class="hlt">hydrothermal</span> fields at Iheya North Knoll (27 47'N, 126 54'E), at Izena Hole Jade <span class="hlt">site</span> (27 16'N, 127 05'E) and at Izena Hole Hakurei <span class="hlt">site</span> (27 15'N, 127 04'E) were selected as exploration targets, to focus on a <span class="hlt">hydrothermal</span> fluid circulation system that develops in sediment consists of volcaniclastic and hemipelagic materials. In this presentation, we will report mineralogy of <span class="hlt">hydrothermal</span> precipitates and altered clay minerals together with geochemistry of pore fluids, to discuss <span class="hlt">hydrothermal</span> interactions beneath an active <span class="hlt">hydrothermal</span> field. In the Iheya North Knoll <span class="hlt">hydrothermal</span> field, the BMS drilling successfully attained to 453 cmbsf at the station 200 meters apart from the central mound area. The obtained core consisted almost entirely of grayish white altered mud that was identified as kaolinite by XRD. Pore fluid from the corresponding depth showed enrichment in major cations (Na, K, Ca and Mg) and Cl, which may be explained as a result of involvement of water into the kaolinite. Since kaolinite is considered as stable in rather acidic environment, its abundant occurrence beneath the seafloor would be attributed to a unique <span class="hlt">hydrothermal</span> interaction. A possible scenario is intrusion of the vapor-rich <span class="hlt">hydrothermal</span> component that has experienced phase separation. In the Jade <span class="hlt">hydrothermal</span> fields in the Izena Hole, the BMS drilling successfully attained to 529 cmbsf at the marginal part of a <span class="hlt">hydrothermal</span> field. The obtained core comprised grayish white <span class="hlt">hydrothermal</span> altered mud below 370 cmbsf. Occurrence of native sulphur is also identified. Unfortunately, pore fluid could not be extracted from the intense alteration layer. In the Hakurei <span class="hlt">hydrothermal</span> fields in the Izena Hole, the BMS drilling successfully attained to 610 cmbsf near one of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9243019','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9243019"><span id="translatedtitle">Exploration strategies for <span class="hlt">hydrothermal</span> deposits.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Horn, R A</p> <p>1996-01-01</p> <p>With unlimited money the most certain strategy for finding most <span class="hlt">hydrothermal</span> metal deposits would be by drilling to 5000 m at 50 m spacing. However, the cost would far outweigh the benefit of the discoveries. Geological knowledge and exploration techniques may be used to obtain the greatest benefit for minimum cost, and to concentrate human and material resources in the most economic way in areas with the highest probability of discovery. This paper reviews the economic theory of exploration based on expected value, and the application of geological concepts and exploration techniques to exploration for <span class="hlt">hydrothermal</span> deposits. Exploration techniques for <span class="hlt">hydrothermal</span>-systems on Mars would include geochemistry and particularly passive geophysical methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP11A..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP11A..01S"><span id="translatedtitle">The magnetic signature of ultramafic-hosted <span class="hlt">hydrothermal</span> systems (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Szitkar, F.; Dyment, J.; Honsho, C.; Horen, H.; Fouquet, Y.</p> <p>2013-12-01</p> <p>While the magnetic response of basalt-hosted <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> is well known, that of ultramafic-hosted <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> (UMHS) remains poorly documented. Here we present the magnetic signature of three of the six UMHS investigated to date on the Mid-Atlantic Ridge, i.e. <span class="hlt">sites</span> Rainbow, Ashadze (1 and 2), and Logachev. Two magnetic signatures are observed. <span class="hlt">Sites</span> Rainbow and Ashadze 1 are both characterized by a positive reduced-to-the-pole magnetic anomaly, i.e. a positive magnetization contrast. Conversely, <span class="hlt">sites</span> Ashadze 2 and Logachev do not exhibit any clear magnetic signature. Rock-magnetic measurements on samples from <span class="hlt">site</span> Rainbow reveal a strong magnetization (~30 A/m adding induced and remanent contributions) borne by sulfide-impregnated serpentinites; the magnetic carrier being magnetite. This observation can be explained by three (non exclusive) processes: (1) higher temperature serpentinization at the <span class="hlt">site</span> resulting in the formation of more abundant / more strongly magnetized magnetite; (2) the reducing <span class="hlt">hydrothermal</span> fluid protecting magnetite at the <span class="hlt">site</span> from the oxidation which otherwise affects magnetite in contact with seawater; and (3) the formation of primary (<span class="hlt">hydrothermal</span>) magnetite. We apply a new inversion method developed by Honsho et al. (2012) to the high-resolution magnetic anomalies acquired 10 m above seafloor at <span class="hlt">sites</span> Rainbow and Ashadze 1. This method uses the Akaike Bayesian Information Criterion (ABIC) and takes full advantage of the near-seafloor measurements, avoiding the upward-continuation (i.e. loss of resolution) of other inversion schemes. This inversion reveals a difference in the intensity of equivalent magnetization obtained assuming a 100 m thick magnetic layer, ~30 A/m at <span class="hlt">site</span> Rainbow and only 8A/m at <span class="hlt">site</span> Ashadze, suggesting a thinner or less magnetized source for the latter. <span class="hlt">Hydrothermal</span> <span class="hlt">sites</span> at Ashadze 2 and Logachev are much smaller (of the order of 10 m) than the previous ones (several 100 m). These <span class="hlt">sites</span>, known as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5346624','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5346624"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> processes at seafloor spreading centers,</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sleep, N.H.</p> <p>1983-01-01</p> <p>This chapter discusses the initial entry of <span class="hlt">hydrothermal</span> seawater into deep levels of the oceanic crust, the effectiveness of <span class="hlt">hydrothermal</span> circulation in cooling the crust, the geometry of <span class="hlt">hydrothermal</span> circulation, the relationship between the <span class="hlt">hydrothermal</span> circulation and the magma chamber, the reaction of the oceanic crust with the seawater, and the identification of the <span class="hlt">hydrothermal</span> fluid which alters a rock sample. Topics considered include the crack front, observation relevant to the crack front, the limitations of the crack front hypothesis, the observed pattern of <span class="hlt">hydrothermal</span> alteration, the nature of the <span class="hlt">hydrothermal</span> fluid, the physics of large scale convection, and convection through crack zones. Knowledge of <span class="hlt">hydrothermal</span> circulation at the ridge axis is based on sampling of the <span class="hlt">hydrothermal</span> fluid, indirect geophysical measurements of the oceanic crust, and studies of rocks which are believed to have undergone <span class="hlt">hydrothermal</span> alteration at the ridge axis. Includes 2 drawings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004EOSTr..85...37E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004EOSTr..85...37E"><span id="translatedtitle">Explorations of Mariana Arc Volcanoes Reveal New <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Embley, R. W.; Baker, E. T.; Chadwick, W. W., Jr.; Lupton, J. E.; Resing, J. A.; Massoth, G. J.; Nakamura, K.</p> <p>2004-01-01</p> <p>Some 20,000 km of volcanic arcs, roughly one-third the length of the global mid-ocean ridge (MOR) system, rim the western Pacific Ocean. Compared to 25 years of <span class="hlt">hydrothermal</span> investigations along MORs, exploration of similar activity on the estimated ~600 submarine arc volcanoes is only beginning [Ishibashi and Urabe, 1995; De Ronde et al., 2003]. To help alleviate this under-sampling, the R/V T. G. Thompson was used in early 2003 (9 February to 5 March) to conduct the first complete survey of <span class="hlt">hydrothermal</span> activity along 1200 km of the Mariana intra-oceanic volcanic arc. This region includes both the Territory of Guam and the Commonwealth of the Northern Mariana Islands. The expedition mapped over 50 submarine volcanoes with stunning new clarity (Figures 1 and 2) and found active <span class="hlt">hydrothermal</span> discharge at 12 <span class="hlt">sites</span>, including the southern back-arc <span class="hlt">site</span>. This includes eight new <span class="hlt">sites</span> along the arc (West Rota, Northwest Rota, E. Diamante, Zealandia Bank, Maug Caldera, Ahyi, Daikoku, and Northwest Eifuku) and four <span class="hlt">sites</span> of previously known <span class="hlt">hydrothermal</span> activity (Seamount X, Esmeralda, Kasuga 2, and Nikko) (Figures 1 and 2). The mapping also fortuitously provided a ``before'' image of the submarine flanks of Anatahan Island, which had its first historical eruption on 10 May 2003 (Figures 1 and 3).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024075','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024075"><span id="translatedtitle">Geochemistry of fluid phases and sediments: Relevance to <span class="hlt">hydrothermal</span> circulation in Middle Valley, ODP Legs 139 and 169</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gieskes, J.M.; Simoneit, B.R.T.; Shanks, Wayne C.; Goodfellow, W.D.; James, R.H.; Baker, P.A.; Ishibashi, J.-I.</p> <p>2002-01-01</p> <p>Geochemical and isotopic studies of pore fluids and solid phases recovered from the Dead Dog and Bent Hill <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in Middle Valley (Ocean Drilling Program Leg 169) have been compared with similar data obtained previously from these <span class="hlt">sites</span> during Ocean Drilling Program Leg 139. Although generally the <span class="hlt">hydrothermal</span> systems reflect non-steady state conditions, the data allow an assessment of the history of the <span class="hlt">hydrothermal</span> processes. Sediment K/A1 ratios as well as the distribution of anhydrite in the sediments suggest that the Dead Dog <span class="hlt">hydrothermal</span> field has been, and still is, active. In contrast, similar data in the Bent Hill <span class="hlt">hydrothermal</span> field indicate a waning of <span class="hlt">hydrothermal</span> activity. Pore fluid and <span class="hlt">hydrothermal</span> vent data in the Dead Dog <span class="hlt">hydrothermal</span> field are similar in nature to the data collected during ODP Leg 139. In the area of the Bent Hill sulfide deposit, however, the pore water data indicate that recent wholesale flushing of the sediment column with relatively unaltered seawater has obliterated a previous record of <span class="hlt">hydrothermal</span> activity in the pore fluids. Data from the deepest part of Hole 1035A in the Bent Hill locality show the presence of <span class="hlt">hydrothermal</span> fluids at greater depths in this area. This suggests the origin of the <span class="hlt">hydrothermal</span> fluids found to be emanating from Hole 1035F, which constitutes one of the first man made <span class="hlt">hydrothermal</span> vents in the Middle Valley <span class="hlt">hydrothermal</span> system. Similarly, CORKed Hole 858G, because of seal failures, has acted as a <span class="hlt">hydrothermal</span> vent, with sulfide deposits forming inside the CORK. ?? 2002 Elsevier Science Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8487B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8487B"><span id="translatedtitle">Distribution, structure and temporal variability of <span class="hlt">hydrothermal</span> outflow at a slow-spreading <span class="hlt">hydrothermal</span> field from seafloor image mosaics.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barreyre, Thibaut; Escartin, Javier; Cannat, Mathilde; Garcia, Rafael; Science Party, Momar'08; Science Party, Bathyluck'09</p> <p>2010-05-01</p> <p>The Lucky Strike <span class="hlt">hydrothermal</span> <span class="hlt">site</span>, located South of the Azores along the Mid-Atlantic Ridge, is one of the largest and best-known active <span class="hlt">hydrothermal</span> fields along the ridge system. This <span class="hlt">site</span> within the MoMAR area is also the target for the installation in 2010 of a pilot deep-sea observatory with direct telemetry to land, to be part of the European Seafloor Observatory Network (ESONET). The Lucky Strike <span class="hlt">hydrothermal</span> <span class="hlt">site</span> has seen extensive high-resolution, near-bottom geophysical surveys in 1996 (Lustre'96), 2006 (Momareto06), 2008 (MOMAR08) and 2009 (Bathyluck09). Vertically acquired black-and-white electronic still camera images have been projected and georeferenced to obtain 3 image mosaics covering the zone of active venting, extending ~ 700x800 m2, and with full image resolution (~10 mm pixels). These data allow us to study how <span class="hlt">hydrothermal</span> outflow is structured, including the relationships between the zones of active high-temperature venting, areas of diffuse outflow, and the geological structure (nature of the substrate, faults and fissures, sediments, etc.). <span class="hlt">Hydrothermal</span> outflow is systematically associated with bacterial mats that are easily identified in the imagery, allowing us to study temporal variability at two different scales. Over the 13-year period we can potentially track changes in both the geometry and intensity of <span class="hlt">hydrothermal</span> activity throughout the system; our preliminary study of the Eiffel Tower, White Castle and Mt Segur indicate that activity has been sustained in recent times, with small changes in the detailed geometry of the diffuse outflow and its intensity. At longer times scales (hundreds to 1000 years?) imagery also shows evidence of areas of venting that are no longer active, often associated with the active structures. In combination with the high-resolution bathymetry, the imagery data thus allow us to characterize the shallow structure of <span class="hlt">hydrothermal</span> outflow at depth, the structural and volcanic control, and ultimately</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1912.2028W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1912.2028W"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Chemotrophic Biosignatures on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Westall, F.; Campbell, K. A.; Gautret, P.; Bréhéret, J.; Foucher, F.; Vago, J.; Kminek, G.; Hubert, A.; Hickman-Lewis, K.; Cockell, C. S.</p> <p>2016-05-01</p> <p><span class="hlt">Hydrothermal</span> chemotrophic biosignatures (morphological and geo-organochemical) were common in shallow water on the anaerobic early Earth, preserved by silicification. They are representative also of shallow crustal biosignatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS51E..02C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS51E..02C"><span id="translatedtitle">Near-Seafloor Magnetic Exploration of Submarine <span class="hlt">Hydrothermal</span> Systems in the Kermadec Arc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caratori Tontini, F.; de Ronde, C. E. J.; Tivey, M.; Kinsey, J. C.</p> <p>2014-12-01</p> <p>Magnetic data can provide important information about <span class="hlt">hydrothermal</span> systems because <span class="hlt">hydrothermal</span> alteration can drastically reduce the magnetization of the host volcanic rocks. Near-seafloor data (≤70 m altitude) are required to map <span class="hlt">hydrothermal</span> systems in detail; Autonomous Underwater Vehicles (AUVs) are the ideal platform to provide this level of resolution. Here, we show the results of high-resolution magnetic surveys by the ABE and Sentry AUVs for selected submarine volcanoes of the Kermadec arc. 3-D magnetization models derived from the inversion of magnetic data, when combined with high resolution seafloor bathymetry derived from multibeam surveys, provide important constraints on the subseafloor geometry of <span class="hlt">hydrothermal</span> upflow zones and the structural control on the development of seafloor <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> as well as being a tool for the discovery of previously unknown <span class="hlt">hydrothermal</span> <span class="hlt">sites</span>. Significant differences exist between the magnetic expressions of <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> at caldera volcanoes ("donut" pattern) and cones ("Swiss cheese" pattern), respectively. Subseafloor 3-D magnetization models also highlight structural differences between focused and diffuse vent <span class="hlt">sites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010shcg.book..599B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010shcg.book..599B"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Growth of Polyscale Crystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Byrappa, Kullaiah</p> <p></p> <p>In this chapter, the importance of the <span class="hlt">hydrothermal</span> technique for growth of polyscale crystals is discussed with reference to its efficiency in synthesizing high-quality crystals of various sizes for modern technological applications. The historical development of the <span class="hlt">hydrothermal</span> technique is briefly discussed, to show its evolution over time. Also some of the important types of apparatus used in routine <span class="hlt">hydrothermal</span> research, including the continuous production of nanosize crystals, are discussed. The latest trends in the <span class="hlt">hydrothermal</span> growth of crystals, such as thermodynamic modeling and understanding of the solution chemistry, are elucidated with appropriate examples. The growth of some selected bulk, fine, and nanosized crystals of current technological significance, such as quartz, aluminum and gallium berlinites, calcite, gemstones, rare-earth vanadates, electroceramic titanates, and carbon polymorphs, is discussed in detail. Future trends in the <span class="hlt">hydrothermal</span> technique, required to meet the challenges of fast-growing demand for materials in various technological fields, are described. At the end of this chapter, an Appendix 18.A containing a more or less complete list of the characteristic families of crystals synthesized by the <span class="hlt">hydrothermal</span> technique is given with the solvent and pressure-temperature (PT) conditions used in their synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17..375D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17..375D"><span id="translatedtitle">Geologic evolution of the Lost City <span class="hlt">Hydrothermal</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denny, Alden R.; Kelley, Deborah S.; Früh-Green, Gretchen L.</p> <p>2016-02-01</p> <p>The Lost City <span class="hlt">Hydrothermal</span> Field (LCHF) is a novel serpentinite-hosted vent field located on the Atlantis Massif southern wall. Results of 2 m resolution bathymetry, side scan, and video and still imagery, integrated with direct submersible observations provide the first high-resolution geologic map of the LCHF. These data form the foundation for an evolutionary model for the vent system over the past >120,000 years. The field is located on a down-dropped bench 70 m below the summit of the massif. The bench is capped by breccia and pelagic carbonate deposits underlain by variably deformed and altered serpentinite and gabbroic rocks. <span class="hlt">Hydrothermal</span> activity is focused at the 60 m tall, 100 m across, massive carbonate edifice "Poseidon," which is venting 91°C fluid. <span class="hlt">Hydrothermal</span> activity declines south and west of the Poseidon complex and dies off completely at distances greater than 200 m. East of Poseidon, the most recent stage of <span class="hlt">hydrothermal</span> flow is characterized by egress of diffuse fluids from narrow fissures within a low-angle, anastomosing mylonite zone. South of the area of current <span class="hlt">hydrothermal</span> activity, there is evidence of two discrete previously unrecognized relict fields. Active venting <span class="hlt">sites</span> defined by carbonate-filled fissures that cut the carbonate cap rock at the summit of the massif mark the present-day northernmost extent of venting. These spatial relationships reflect multiple stages of field development, the northward migration of venting over time, and the likely development of a nascent field at the massif summit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1060L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1060L"><span id="translatedtitle">Seafloor <span class="hlt">Hydrothermal</span> Activity at the Galapagos Triple Junction, East Pacific Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, H.; Yu, Z.; Zhang, G.; Tao, C.; Chen, S.</p> <p>2014-12-01</p> <p>Since the first discovery of black smokers on the Gaplapgaos spreading center, over 500 <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> have been confirmed on the mid-ocean ridge, arc and back-arc settings (Beaulieu et al., 2013). However, the <span class="hlt">hydrothermal</span> activity at triple-junction has not received much attention. Consequently, there are outstanding questions regarding the features of the <span class="hlt">hydrothermal</span> system, and the effect of the <span class="hlt">hydrothermal</span> circulation on the tectonic activity of the triple-junction. In 2009, the Chinese Dayang Cruise 21 discovered the Precious Stone field (PSF) on the Dietz Semount at the southern flank of the Galapagos triple junction (GTJ). Most studies of the GTJ focus on the topographictectonic and stresssimulation, which suggest that the GTJ had complex evoluation(Smith et al., 2011, 2013; Mitchell et al., 2011,Schouten et al., 2012). Water anomay were clear detected and samples of <span class="hlt">hydrothermal</span> deposit and rocks were collected by TV-Grab (Figure.1). This study aims to understand the geological features of the PSF related <span class="hlt">hydrothermal</span> activity. <span class="hlt">Hydrothermal</span> mineralization Three types of sedimentary <span class="hlt">hydrothermal</span> deposits representing three different <span class="hlt">hydrothermal</span> activity stages (Figure 1)are confirmed in the PSF: 1) sediments with native sulfur and pyrite clasts(Type I), 2) Fe—Mn oxides (Type II), and 3) clay minerals mainlynontronite(Type III). Type II sedimentsprecipitate early and the source comprises of clasts of distal <span class="hlt">hydrothermal</span> plume. The nontronite-rich sediments propably derive from the low-temperature alteration of Fe—Mn oxides. Type 1 sediments are found on the active <span class="hlt">hydrothermal</span> venting field. <span class="hlt">Hydrothermal</span> plume Water anomaly were detected at the southewestern PSF. We observed widespreadsedimentary <span class="hlt">hydrothermal</span> depositsin the western PSF, but no water anomaly. According to the results of five water anomaly dectection lines, we predicted the existence of three <span class="hlt">hydrothermal</span> vents in the PSF. Seafloor type inversion Multi-beam backscatter data were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/105051','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/105051"><span id="translatedtitle">Hydraulic characterization of <span class="hlt">hydrothermally</span> altered Nopal tuff</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Green, R.T.; Meyer-James, K.A.; Rice, G.</p> <p>1995-07-01</p> <p>Understanding the mechanics of variably saturated flow in fractured-porous media is of fundamental importance to evaluating the isolation performance of the proposed high-level radioactive waste repository for the Yucca Mountain <span class="hlt">site</span>. Developing that understanding must be founded on the analysis and interpretation of laboratory and field data. This report presents an analysis of the unsaturated hydraulic properties of tuff cores from the Pena Blanca natural analog <span class="hlt">site</span> in Mexico. The basic intent of the analysis was to examine possible trends and relationships between the hydraulic properties and the degree of <span class="hlt">hydrothermal</span> alteration exhibited by the tuff samples. These data were used in flow simulations to evaluate the significance of a particular conceptual (composite) model and of distinct hydraulic properties on the rate and nature of water flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B14E..06A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B14E..06A"><span id="translatedtitle">Genome-resolved metagenomics reveals that sulfur metabolism dominates the microbial ecology of rising <span class="hlt">hydrothermal</span> plumes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anantharaman, K.; Breier, J. A., Jr.; Jain, S.; Reed, D. C.; Dick, G.</p> <p>2015-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> plumes occur when hot fluids from <span class="hlt">hydrothermal</span> vents replete with chemically reduced elements and compounds like sulfide, methane, hydrogen, ammonia, iron and manganese mix with cold, oxic seawater. Chemosynthetic microbes use these reduced chemicals to power primary production and are pervasive throughout the deep sea, even at <span class="hlt">sites</span> far removed from <span class="hlt">hydrothermal</span> vents. Although neutrally-buoyant <span class="hlt">hydrothermal</span> plumes have been well-studied, rising <span class="hlt">hydrothermal</span> plumes have received little attention even though they represent an important interface in the deep-sea where microbial metabolism and particle formation processes control the transformation of important elements and impact global biogeochemical cycles. In this study, we used genome-resolved metagenomic analyses and thermodynamic-bioenergetic modeling to study the microbial ecology of rising <span class="hlt">hydrothermal</span> plumes at five different <span class="hlt">hydrothermal</span> vents spanning a range of geochemical gradients at the Eastern Lau Spreading Center (ELSC) in the Western Pacific Ocean. Our analyses show that differences in the geochemistry of <span class="hlt">hydrothermal</span> vents do not manifest in microbial diversity and community composition, both of which display only minor variance across ELSC <span class="hlt">hydrothermal</span> plumes. Microbial metabolism is dominated by oxidation of reduced sulfur species and supports a diversity of bacteria, archaea and viruses that provide intriguing insights into metabolic plasticity and virus-mediated horizontal gene transfer in the microbial community. The manifestation of sulfur oxidation genes in hydrogen and methane oxidizing organisms hints at metabolic opportunism in deep-sea microbes that would enable them to respond to varying redox conditions in <span class="hlt">hydrothermal</span> plumes. Finally, we infer that the abundance, diversity and metabolic versatility of microbes associated with sulfur oxidation impart functional redundancy that could allow it to persist in the dynamic settings of <span class="hlt">hydrothermal</span> plumes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.V41B2076G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.V41B2076G"><span id="translatedtitle">Bacterial Diets of Primary Consumers at <span class="hlt">Hydrothermal</span> Vents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Govenar, B.; Shank, T. M.</p> <p>2008-12-01</p> <p>Chemical energy produced by mixing <span class="hlt">hydrothermal</span> fluids and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea <span class="hlt">hydrothermal</span> vents is formed by chemolithoautotrophic bacteria that use the energy from the oxidation of reduced chemicals to fix inorganic carbon into simple sugars. With the exception of a few species that have chemolithoautotropic bacterial symbionts, most of the vent-endemic macrofauna are heterotrophs that feed on free-living bacteria, protists, and other invertebrates. The most abundant and diverse group of primary consumers in <span class="hlt">hydrothermal</span> vent communities belong to the Gastropoda, particularly the patellomorph limpets. Gastropod densities can be as high as 2000 individuals m-2, and there can be as many as 13 species of gastropods in a single aggregation of the siboglinid tubeworm Riftia pachyptila and more than 40 species along the East Pacific Rise. Some gastropods are ubiquitous and others are found in specific microhabitats, stages of succession, or associated with different foundation species. To determine the mechanisms of species coexistence (e.g. resource partitioning or competition) among <span class="hlt">hydrothermal</span> vent primary consumers and to track the flow of energy in <span class="hlt">hydrothermal</span> vent communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring <span class="hlt">hydrothermal</span> vent gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow <span class="hlt">hydrothermal</span> vent <span class="hlt">site</span> on the East Pacific Rise. Unique haplotypes of the 16S gene that fell among the epsilon-proteobacteria were found in the guts of every species, and two species had gut contents that were similar only to epsilon-proteobacteria. Two species had gut contents that also included haplotypes that clustered with delta-proteobacteria, and one species had gut contents that clustered with alpha- proteobacteria. Differences in the diets</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BVol...77..102B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BVol...77..102B"><span id="translatedtitle">The <span class="hlt">hydrothermal</span> alteration of cooling lava domes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ball, Jessica L.; Stauffer, Philip H.; Calder, Eliza S.; Valentine, Greg A.</p> <p>2015-12-01</p> <p><span class="hlt">Hydrothermal</span> alteration is a recognized cause of volcanic instability and edifice collapse, including that of lava domes or dome complexes. Alteration by percolating fluids transforms primary minerals in dome lavas to weaker secondary products such as clay minerals; moreover, secondary mineral precipitation can affect the porosity and permeability of dome lithologies. The location and intensity of alteration in a dome depend heavily on fluid pathways and availability in conjunction with heat supply. Here we investigate postemplacement lava dome weakening by <span class="hlt">hydrothermal</span> alteration using a finite element numerical model of water migration in simplified dome geometries. This is combined with the rock alteration index (RAI) to predict zones of alteration and secondary mineral precipitation. Our results show that alteration potential is highest at the interface between the hot core of a lava dome and its clastic talus carapace. The longest lived alteration potential fields occur in domes with persistent heat sources and permeabilities that allow sufficient infiltration of water for alteration processes, but not so much that domes cool quickly. This leads us to conclude that alteration-induced collapses are most likely to be shallow seated and originate in the talus or talus/core interface in domes which have a sustained supply of magmatic heat. Mineral precipitation at these zones of permeability contrast could create barriers to fluid flow, potentially causing gas pressurization which might promote deeper seated and larger volume collapses. This study contributes to our knowledge of how <span class="hlt">hydrothermal</span> alteration can affect lava domes and provides constraints on potential <span class="hlt">sites</span> for alteration-related collapses, which can be used to target hazard monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10114744','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10114744"><span id="translatedtitle">Modeling of the fault-controlled <span class="hlt">hydrothermal</span> ore-forming systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pek, A.A.; Malkovsky, V.I.</p> <p>1993-07-01</p> <p>A necessary precondition for the formation of <span class="hlt">hydrothermal</span> ore deposits is a strong focusing of <span class="hlt">hydrothermal</span> flow as fluids move from the fluid source to the <span class="hlt">site</span> of ore deposition. The spatial distribution of <span class="hlt">hydrothermal</span> deposits favors the concept that such fluid flow focusing is controlled, for the most part, by regional faults which provide a low resistance path for <span class="hlt">hydrothermal</span> solutions. Results of electric analog simulations, analytical solutions, and computer simulations of the fluid flow, in a fault-controlled single-pass advective system, confirm this concept. The influence of the fluid flow focusing on the heat and mass transfer in a single-pass advective system was investigated for a simplified version of the metamorphic model for the genesis of greenstone-hosted gold deposits. The spatial distribution of ore mineralization, predicted by computer simulation, is in reasonable agreement with geological observations. Computer simulations of the fault-controlled thermoconvective system revealed a complex pattern of mixing <span class="hlt">hydrothermal</span> solutions in the model, which also simulates the development of the modern <span class="hlt">hydrothermal</span> systems on the ocean floor. The specific feature of the model considered, is the development under certain conditions of an intra-fault convective cell that operates essentially independently of the large scale circulation. These and other results obtained during the study indicate that modeling of natural fault-controlled <span class="hlt">hydrothermal</span> systems is instructive for the analysis of transport processes in man-made <span class="hlt">hydrothermal</span> systems that could develop in geologic high-level nuclear waste repositories.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021322','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021322"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of ammonium illite</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sucha, V.; Elsass, F.; Eberl, D.D.; Kuchta, L'.; Madejova, J.; Gates, W.P.; Komadel, P.</p> <p>1998-01-01</p> <p>Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starting materials for <span class="hlt">hydrothermal</span> synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by <span class="hlt">hydrothermal</span> treatment at 300??C. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. <span class="hlt">Hydrothermal</span> treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70170389','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70170389"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems and volcano geochemistry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fournier, R.O.</p> <p>2007-01-01</p> <p>The upward intrusion of magma from deeper to shallower levels beneath volcanoes obviously plays an important role in their surface deformation. This chapter will examine less obvious roles that <span class="hlt">hydrothermal</span> processes might play in volcanic deformation. Emphasis will be placed on the effect that the transition from brittle to plastic behavior of rocks is likely to have on magma degassing and <span class="hlt">hydrothermal</span> processes, and on the likely chemical variations in brine and gas compositions that occur as a result of movement of aqueous-rich fluids from plastic into brittle rock at different depths. To a great extent, the model of <span class="hlt">hydrothermal</span> processes in sub-volcanic systems that is presented here is inferential, based in part on information obtained from deep drilling for geothermal resources, and in part on the study of ore deposits that are thought to have formed in volcanic and shallow plutonic environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JGR....98.9621R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JGR....98.9621R"><span id="translatedtitle">Introduction to Atlantic <span class="hlt">Hydrothermal</span> Activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rona, Peter A.; Thompson, Geoffrey</p> <p>1993-06-01</p> <p>Seafloor <span class="hlt">hydrothermal</span> research has advanced rapidly from local to global scope through a sequence of discoveries. <span class="hlt">Hydrothermal</span> research at seafloor spreading centers began in the mid-1960s with the discovery of hot metalliferous brines and sediments ponded in deeps along the slow spreading (half rate 1 cm yr-1) axis of the Red Sea [Chamock, 1964; Miller, 1964; Swallow and Crease, 1965; Miller et al., 1966; Hunt et al., 1967; Bischoff, 1969]. At the same time a <span class="hlt">hydrothermal</span> metalliferous component was identified in sediments of the East Pacific Rise [Skomyakova, 1965; Arrhenins and Bonatti, 1965; Boström and Peterson, 1966]. Geophysicists recognized that heat flow measurements at spreading centers could only be explained by convective cooling of the crust with circulating seawater [Elder, 1967; Lister, 1972].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS23D..08B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS23D..08B"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Activity in the Northern Guaymas Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berndt, C.; Hensen, C.; Mortera-Gutierrez, C. A.; Sarkar, S.; Geilert, S.; Schmidt, M.; Liebetrau, V.; Kipfer, R.; Scholz, F.; Doll, M.; Muff, S.; Karstens, J.; Böttner, C.; Chi, W. C.; Moser, M.; Behrendt, R.; Fiskal, A.; Evans, T.; Planke, S.; Lizarralde, D.; Lever, M. A.</p> <p>2015-12-01</p> <p>Rift-related magmatism in the Guaymas Basin, Gulf of California induces <span class="hlt">hydrothermal</span> activity within the basin sediments. Mobilized fluids migrate to the seafloor where they are emitted into the water column changing ocean chemistry and fuelling chemosynthetic ecosystems. New seismic and geochemical data from the northern rift arm of the Guaymas Basin document the variety of fluid expulsion phenomena from large-scale subsurface sediment mobilization related to contact metamorphosis to focused small-scale structures. The geochemical composition of emitted fluids depends largely on the age of the fluid escape structures with respect to the underlying intrusions. Whereas, old structures are dominated by methane emission, young vent <span class="hlt">sites</span> are characterized by hot fluids that carry a wide range of minerals in solution. The overall high geothermal gradient within the basin (mainly between 160 and 260 °C/km) leads to a thin gas hydrate stability zone. Thus, deep <span class="hlt">hydrothermal</span> fluid advection affects the gas hydrate system and makes it more dynamic than in colder sedimentary basins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B13A0157F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B13A0157F"><span id="translatedtitle">Subsurface Controls on Habitability of <span class="hlt">Hydrothermal</span> Waters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fristad, K. E.; Som, S. M.; Hoehler, T. M.</p> <p>2014-12-01</p> <p>Liquid water alone does not make an environment habitable. Environmental settings dominated by water-rock reactions such as in <span class="hlt">hydrothermal</span> vents and springs are natural targets for astrobiological investigation of waterworlds because the rich geochemical diversity at these locales provides abundant energy in solvent to support microbial life. Hydrogen oxidizers are of particular interest because H2-based metabolisms are widespread and deeply rooted throughout the phylogenetic tree of life, implying they may have emerged extremely early in the evolution, and possibly even the origin, of life on Earth and potentially any other rocky bodies bearing liquid water. Dihydrogen (H2) can be lithogenically produced by the hydrolytic oxidation of the ferrous iron component in Fe-bearing minerals as well as by radiolytic cleavage of water by α, β, or γ radiation produced during the decay of radioactive isotopes. Lithogenic H2 production mechanisms operate across a range of rock types, but the concentration of dissolved H2 available to life is controlled by a number of subsurface factors such as surface geometry, water to rock ratio, production rate, and fluid flux. These factors are often controlled by the larger geologic and structural context of a particular <span class="hlt">site</span>. We present results of an ongoing project that surveys H2 concentrations from terrestrial <span class="hlt">hydrothermal</span> waters in diverse chemical and physical settings. Aqueous H2 concentrations and potential subsurface controls are presented for <span class="hlt">sites</span> across the western U.S. including Yellowstone National Park, Lassen Volcanic National Park, and Iceland. In coordination with field data, we also investigate the habitability of various <span class="hlt">sites</span> numerically by coupling a geochemical model of water-rock interaction with that of single-cell methanogenesis and compute a habitability index for the given environment. In particular, we investigate the control that temperature, rock composition, water composition, and water to rock ratio</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP23B3675D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP23B3675D"><span id="translatedtitle">Untangling Magmatic Processes and <span class="hlt">Hydrothermal</span> Alteration of in situ Superfast Spreading Ocean Crust at ODP/IODP <span class="hlt">Site</span> 1256 with Fuzzy c-means Cluster Analysis of Rock Magnetic Properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dekkers, M. J.; Heslop, D.; Herrero-Bervera, E.; Acton, G.; Krasa, D.</p> <p>2014-12-01</p> <p>Ocean Drilling Program (ODP)/Integrated ODP (IODP) Hole 1256D (6.44.1' N, 91.56.1' W) on the Cocos Plate occurs in 15.2 Ma oceanic crust generated by superfast seafloor spreading. Presently, it is the only drill hole that has sampled all three oceanic crust layers in a tectonically undisturbed setting. Here we interpret down-hole trends in several rock-magnetic parameters with fuzzy c-means cluster analysis, a multivariate statistical technique. The parameters include the magnetization ratio, the coercivity ratio, the coercive force, the low-field susceptibility, and the Curie temperature. By their combined, multivariate, analysis the effects of magmatic and <span class="hlt">hydrothermal</span> processes can be evaluated. The optimal number of clusters - a key point in the analysis because there is no a priori information on this - was determined through a combination of approaches: by calculation of several cluster validity indices, by testing for coherent cluster distributions on non-linear-map plots, and importantly by testing for stability of the cluster solution from all possible starting points. Here, we consider a solution robust if the cluster allocation is independent of the starting configuration. The five-cluster solution appeared to be robust. Three clusters are distinguished in the extrusive segment of the Hole that express increasing <span class="hlt">hydrothermal</span> alteration of the lavas. The sheeted dike and gabbro portions are characterized by two clusters, both with higher coercivities than in lava samples. Extensive alteration, however, can obliterate magnetic property differences between lavas, dikes, and gabbros. The imprint of thermochemical alteration on the iron-titanium oxides is only partially related to the porosity of the rocks. All clusters display rock magnetic characteristics in line with a stable NRM. This implies that the entire sampled sequence of ocean crust can contribute to marine magnetic anomalies. Determination of the absolute paleointensity with thermal techniques is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V21C2737W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V21C2737W"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> plumes in the NE Lau basin: A regional perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walker, S. L.; Baker, E. T.</p> <p>2013-12-01</p> <p>Exploration for mineral resources and the presence of an extensive plume of excess 3He centered at 1750 m water depth in the Samoa-Tonga-Fiji region (Lupton, 2004) have motivated exploration for active <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> in the NE Lau basin during the past decade. The region is tectonically complex with back-arc spreading centers, rift zones, and volcanic centers, all of which potentially host active venting and/or active volcanism. To date, 400 km of the three back-arc spreading centers in the NE Lau basin (FRSC, Fonualei Rift and Spreading Center; MTJ, Mangatolu Triple Junction; and NELSC, Northeastern Lau Spreading Center) plus several volcanic centers have been systematically surveyed for <span class="hlt">hydrothermal</span> plumes using towed CTD or MAPR arrays that include both optical backscatter and oxidation-reduction potential (ORP) sensors. The FRSC, where spreading rates range from 47 mm/a in the south to 85 mm/a in the north, has 5 active <span class="hlt">sites</span> (plume depths ranging from 1300-2200 m) distributed one every ~40 km over its 200 km length. There is evidence for 4 active <span class="hlt">sites</span> (plume depths range from 1950-2380 m) along the 150 km combined length of the MTJ segments, however plumes were optically weak (dNTU < 0.02) and except for one location along the northeastern limb, no ORP anomalies were detected. Plumes were observed off-axis to the MTJ at a bathymetric high adjacent to the northeastern limb (1700 m) as well as over the summit of a cratered volcanic edifice east of the central junction (1200-1300 m). The southern segment of the NELSC was the <span class="hlt">site</span> of an active eruption in 2008 which injected event plumes throughout the water column (900-1600 m depth range) in addition to the chronic plume from the Maka massive sulfide vent <span class="hlt">site</span> (1500 m). There is evidence for at least two additional active areas along the northern segments of the NELSC (1800-1900 m). Several volcanoes in the region are <span class="hlt">hydrothermally</span> active ranging from the northernmost volcano on the Tonga arc (Niua</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6262G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6262G"><span id="translatedtitle">Coupled cycling of Fe and organic carbon in submarine <span class="hlt">hydrothermal</span> systems: Impacts on Ocean Biogeochemistry?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>German, Christopher; Sander, Sylvia; Legendre, Louis; Niquil, Nathalie; Working Group 135</p> <p>2014-05-01</p> <p>Submarine <span class="hlt">hydrothermal</span> venting was first discovered in the late 1970s. For decades the potential impact that vent-fluxes could have on global ocean budgets was restricted to consideration of processes in <span class="hlt">hydrothermal</span> plumes in which the majority of chemical species are incorporated into polymetallic sulfide and/or oxyhydroxide particles close to the ridge-crest and sink to the underlying seafloor. This restricted view of the role that <span class="hlt">hydrothermal</span> systems might play in global-ocean budgets has been challenged, more recently, by the recognition that there might also be a significant flux of dissolved Fe from <span class="hlt">hydrothermal</span> systems to the oceans that is facilitated through thermodynamically stable nanoparticles and organic complexation. The latest results from the recently completed US GEOTRACES program, which has traced high concentrations of dissolved Fe over long distances off-axis from the Southern East Pacific Rise near 15°S, only help to confirm the potential that such fluxes might be important at the global scale. In this paper we review field-based and modeling results, including investigations that we have carried out under the auspices of SCOR-InterRidge Working Group 135, that reveal potential relationships between organic carbon (Corg) and Fe in <span class="hlt">hydrothermal</span> plumes and allow us to investigate the roles that <span class="hlt">hydrothermal</span> systems may play in the global biogeochemical cycles of both Fe and Corg. Using the particularly well-studied EPR 9N <span class="hlt">hydrothermal</span> system as our "type locality" - even though we recognize that no one <span class="hlt">site</span> can adequately represent the diversity of all <span class="hlt">hydrothermal</span> systems worldwide - our modeling efforts allow us to reach some significant conclusions concerning: the predicted partitioning of heat fluxes between focused and diffuse flow at ridge axes; and the recognition that while Corg fluxes associated with <span class="hlt">hydrothermal</span> plume removal may be small on the global scale, they are likely to result in extremely pronounced fluxes, locally, to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GMS...188...67P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GMS...188...67P"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> activity at the Arctic mid-ocean ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedersen, Rolf B.; Thorseth, Ingunn H.; Nygård, Tor Eivind; Lilley, Marvin D.; Kelley, Deborah S.</p> <p></p> <p>Over the last 10 years, <span class="hlt">hydrothermal</span> activity has been shown to be abundant at the ultraslow spreading Arctic Mid-Ocean Ridges (AMOR). Approximately 20 active and extinct vent <span class="hlt">sites</span> have been located either at the seafloor, as seawater anomalies, or by dredge sampling <span class="hlt">hydrothermal</span> deposits. Decreasing spreading rates and decreasing influence of the Icelandic hot spot toward the north along the AMOR result in a north-south change from a shallow and magmatically robust to a deep and magmatically starved ridge system. This contrast gives rise to large variability in the ridge geology and in the nature of the associated <span class="hlt">hydrothermal</span> systems. The known vent <span class="hlt">sites</span> at the southern part of the ridge system are either low-temperature or white smoker fields. At the deep, northern parts of the ridge system, a large black smoker field has been located, and seawater anomalies and sulfide deposits suggest that black smoker-type venting is common. Several of these fields may be peridotite-hosted. The <span class="hlt">hydrothermal</span> activity at parts of the AMOR exceeds by a factor of 2 to 3 what would be expected by extrapolating from observations on faster spreading ridges. Higher fracture/fault area relative to the magma volume extracted seems a likely explanation for this. Many of the vent fields at the AMOR are associated with axial volcanic ridges. Strong focusing of magma toward these ridges, deep rifting of the ridges, and subsequent formation of long-lived detachment faults that are rooted below the ridges may be the major geodynamic mechanisms causing the unexpectedly high <span class="hlt">hydrothermal</span> activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5281083','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5281083"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> processes at seafloor spreading centers,</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rona, P.A.; Bostrom, K.; Laubier, L.; Smith, K.L.</p> <p>1983-01-01</p> <p>This book examines research on the description and interpretation of <span class="hlt">hydrothermal</span> and associated phenomena at seafloor spreading centers. An interdisciplinary overview of the subject is presented, including geological, geophysical, geochemical, and biological discoveries. The implications of the discoveries for understanding the earth's heat transfer, geochemical mass balances and cycles, mineralization, and biological adaptation are discussed. Topics considered include geologic setting (e.g., the four dimensions of the spreading axis, geological processes of the mid-ocean ridge), <span class="hlt">hydrothermal</span> convection (e.g., oxygen and hydrogen isotope studies, the basic physics of water penetration into hot rock), Iceland and oceanic ridges (e.g., chemical evidence from Icelandic geothermal systems, the physical environment of <span class="hlt">hydrothermal</span> systems), mass balances and cycles (e.g., reduced gases and bacteria in <span class="hlt">hydrothermal</span> fluids, the effects of <span class="hlt">hydrothermal</span> activity on sedimentary organic matter), ferromanganese deposits, <span class="hlt">hydrothermal</span> mineralization, and the biology of <span class="hlt">hydrothermal</span> vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22235192','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22235192"><span id="translatedtitle">Antarctic marine biodiversity and deep-sea <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chown, Steven L</p> <p>2012-01-01</p> <p>The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea <span class="hlt">hydrothermal</span> vents. Vent ecosystems have been documented from many <span class="hlt">sites</span> across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea <span class="hlt">hydrothermal</span> vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic <span class="hlt">hydrothermal</span> vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea <span class="hlt">hydrothermal</span> vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21833083','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21833083"><span id="translatedtitle">Hydrogen is an energy source for <span class="hlt">hydrothermal</span> vent symbioses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Petersen, Jillian M; Zielinski, Frank U; Pape, Thomas; Seifert, Richard; Moraru, Cristina; Amann, Rudolf; Hourdez, Stephane; Girguis, Peter R; Wankel, Scott D; Barbe, Valerie; Pelletier, Eric; Fink, Dennis; Borowski, Christian; Bach, Wolfgang; Dubilier, Nicole</p> <p>2011-08-11</p> <p>The discovery of deep-sea <span class="hlt">hydrothermal</span> vents in 1977 revolutionized our understanding of the energy sources that fuel primary productivity on Earth. <span class="hlt">Hydrothermal</span> vent ecosystems are dominated by animals that live in symbiosis with chemosynthetic bacteria. So far, only two energy sources have been shown to power chemosynthetic symbioses: reduced sulphur compounds and methane. Using metagenome sequencing, single-gene fluorescence in situ hybridization, immunohistochemistry, shipboard incubations and in situ mass spectrometry, we show here that the symbionts of the <span class="hlt">hydrothermal</span> vent mussel Bathymodiolus from the Mid-Atlantic Ridge use hydrogen to power primary production. In addition, we show that the symbionts of Bathymodiolus mussels from Pacific vents have hupL, the key gene for hydrogen oxidation. Furthermore, the symbionts of other vent animals such as the tubeworm Riftia pachyptila and the shrimp Rimicaris exoculata also have hupL. We propose that the ability to use hydrogen as an energy source is widespread in <span class="hlt">hydrothermal</span> vent symbioses, particularly at <span class="hlt">sites</span> where hydrogen is abundant. PMID:21833083</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21833083','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21833083"><span id="translatedtitle">Hydrogen is an energy source for <span class="hlt">hydrothermal</span> vent symbioses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Petersen, Jillian M; Zielinski, Frank U; Pape, Thomas; Seifert, Richard; Moraru, Cristina; Amann, Rudolf; Hourdez, Stephane; Girguis, Peter R; Wankel, Scott D; Barbe, Valerie; Pelletier, Eric; Fink, Dennis; Borowski, Christian; Bach, Wolfgang; Dubilier, Nicole</p> <p>2011-08-10</p> <p>The discovery of deep-sea <span class="hlt">hydrothermal</span> vents in 1977 revolutionized our understanding of the energy sources that fuel primary productivity on Earth. <span class="hlt">Hydrothermal</span> vent ecosystems are dominated by animals that live in symbiosis with chemosynthetic bacteria. So far, only two energy sources have been shown to power chemosynthetic symbioses: reduced sulphur compounds and methane. Using metagenome sequencing, single-gene fluorescence in situ hybridization, immunohistochemistry, shipboard incubations and in situ mass spectrometry, we show here that the symbionts of the <span class="hlt">hydrothermal</span> vent mussel Bathymodiolus from the Mid-Atlantic Ridge use hydrogen to power primary production. In addition, we show that the symbionts of Bathymodiolus mussels from Pacific vents have hupL, the key gene for hydrogen oxidation. Furthermore, the symbionts of other vent animals such as the tubeworm Riftia pachyptila and the shrimp Rimicaris exoculata also have hupL. We propose that the ability to use hydrogen as an energy source is widespread in <span class="hlt">hydrothermal</span> vent symbioses, particularly at <span class="hlt">sites</span> where hydrogen is abundant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=321305','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=321305"><span id="translatedtitle">Analysis of Dissimilatory Sulfite Reductase and 16S rRNA Gene Fragments from Deep-Sea <span class="hlt">Hydrothermal</span> <span class="hlt">Sites</span> of the Suiyo Seamount, Izu-Bonin Arc, Western Pacific</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nakagawa, Tatsunori; Ishibashi, Jun-Ichiro; Maruyama, Akihiko; Yamanaka, Toshiro; Morimoto, Yusuke; Kimura, Hiroyuki; Urabe, Tetsuro; Fukui, Manabu</p> <p>2004-01-01</p> <p>This study describes the occurrence of unique dissimilatory sulfite reductase (DSR) genes at a depth of 1,380 m from the deep-sea <span class="hlt">hydrothermal</span> vent field at the Suiyo Seamount, Izu-Bonin Arc, Western Pacific, Japan. The DSR genes were obtained from microbes that grew in a catheter-type in situ growth chamber deployed for 3 days on a vent and from the effluent water of drilled holes at 5°C and natural vent fluids at 7°C. DSR clones SUIYOdsr-A and SUIYOdsr-B were not closely related to cultivated species or environmental clones. Moreover, samples of microbial communities were examined by PCR-denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA gene. The sequence analysis of 16S rRNA gene fragments obtained from the vent catheter after a 3-day incubation revealed the occurrence of bacterial DGGE bands affiliated with the Aquificae and γ- and ɛ-Proteobacteria as well as the occurrence of archaeal phylotypes affiliated with the Thermococcales and of a unique archaeon sequence that clustered with “Nanoarchaeota.” The DGGE bands obtained from drilled holes and natural vent fluids from 7 to 300°C were affiliated with the δ-Proteobacteria, genus Thiomicrospira, and Pelodictyon. The dominant DGGE bands retrieved from the effluent water of casing pipes at 3 and 4°C were closely related to phylotypes obtained from the Arctic Ocean. Our results suggest the presence of microorganisms corresponding to a unique DSR lineage not detected previously from other geothermal environments. PMID:14711668</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020059546','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020059546"><span id="translatedtitle">Thiols in <span class="hlt">Hydrothermal</span> Solution: Standard Partial Molal Properties and Their Role in the Organic Geochemistry of <span class="hlt">Hydrothermal</span> Environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schulte, Mitchell D.; Rogers, Karyn L.; DeVincenzi, D. (Technical Monitor)</p> <p>2001-01-01</p> <p>Modern seafloor <span class="hlt">hydrothermal</span> systems are locations where great varieties of geochemistry occur due to the enormous disequilibrium between vent fluids and seawater. The disequilibrium geochemistry has been hypothesized to include reactions to synthesize organic compounds. Despite the incomplete understanding of the carbon budget in <span class="hlt">hydrothermal</span> systems, the organic geochemistry of these <span class="hlt">sites</span> has received little attention. Experimental simulations of these environments, however, indicate that organic compounds may have difficulty forming in a purely aqueous environment. On the other hand, thiols, thioesters and disulfides have been implicated as reaction intermediates between CO or CO2 in experiments of carbon reduction in <span class="hlt">hydrothermal</span> environments, as well as in a variety of biological processes and other abiotic reactions. The reduction of CO2 to thesis, for example, is observed using the FeS-H2S/FeS2 couple to provide the reducing power. We have used recent advances in theoretical geochemistry to estimate the standard partial moral thermodynamic properties and parameters for the revised Helgeson-Kirkham-Flowers equation of state for aqueous straight-chain alkyl thesis. With these data and parameters we have evaluated the role that organic sulfur compounds may play as reaction intermediates during organic compound synthesis. We conclude that organic sulfur compounds may hold the key to the organic chemistry leading to the origin of life in <span class="hlt">hydrothermal</span> settings. These results may also explain the presence of sulfur in a number of biomolecules present in ancient thermophilic microorganisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V23B0606K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V23B0606K"><span id="translatedtitle">Liquid CO2 venting on the seafloor: Yonaguni Knoll IV <span class="hlt">hydrothermal</span> system, Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Konno, U.; Tsunogai, U.; Nakagawa, F.; Nakaseama, M.; Ishibashi, J.; Nunoura, T.; Nakamura, K.</p> <p>2006-12-01</p> <p>In 2000, an active <span class="hlt">hydrothermal</span> <span class="hlt">site</span>, venting high-temperature fluid up to 300 oC, was discovered by Shinkai 6500 on the top of Yonaguni Knoll IV during YK 00-06 cruise in Okinawa Trough. During the subsequent subseafloor survey using Shinkai 6500 in 2003 (YK03-05), vents of liquid CO2 droplets were found at the <span class="hlt">site</span>. Similar liquid CO2 droplets had previously been found at the active <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> at JADE <span class="hlt">hydrothermal</span> field, Okinawa Trough, during the extensive seafloor survey using submersibles in 1989 [Sakai et al., 1990]. Besides, similar liquid CO2 venting has also been recognized in NW Eifuku <span class="hlt">hydrothermal</span> <span class="hlt">site</span> on Izu-Bonin- Mariana arc. It thus appears that liquid CO2 venting might be usual phenomenon in some submarine arc volcanoes. The detailed relation between seafloor venting liquid CO2 and the surrounding high-temperature <span class="hlt">hydrothermal</span> fluid, however, was not clarified in their studies. Furthermore, no definite evidence was obtained for the presence of CO2-hydrate in the subsurface. In this study, in order to discuss the subseafloor processes responsible for producing liquid CO2 at the Yonaguni Knoll IV <span class="hlt">site</span>, as well as the possibility of the occurrence of solid CO2-hydrate within the sediments, we determined the chemical and isotopic compositions of the liquid CO2 found on the <span class="hlt">site</span>, as well as those in <span class="hlt">hydrothermal</span> fluid venting from the surrounding chimneys. In consequence, the ^13C of both CO2 and CH4 in the liquid CO2 almost coincide with those in the <span class="hlt">hydrothermal</span> fluid, suggesting that the liquid CO2 must be derived from the <span class="hlt">hydrothermal</span> fluid. While showing homogeneous ^13C, the <span class="hlt">hydrothermal</span> fluids exhibit wide variation in gas contents. Active phase separation must be taking place within the conduits. Besides, H2-depletion in the liquid CO2 suggests formation of solid CO2-hydrate must also precede the venting of liquid CO2. In conclusion, liquid CO2 must be produced through following subseafloor processes: phase separation of <span class="hlt">hydrothermal</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4250120','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4250120"><span id="translatedtitle">Distal transport of dissolved <span class="hlt">hydrothermal</span> iron in the deep South Pacific Ocean</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fitzsimmons, Jessica N.; Boyle, Edward A.; Jenkins, William J.</p> <p>2014-01-01</p> <p>Until recently, <span class="hlt">hydrothermal</span> vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because <span class="hlt">hydrothermal</span> Fe was believed to precipitate quantitatively near the vent <span class="hlt">site</span>. Based on recent abyssal dFe enrichments near <span class="hlt">hydrothermal</span> vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209–212] argues that some <span class="hlt">hydrothermal</span> Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (<0.4 µm) measurements from the abyssal southeast and southwest Pacific Ocean, where dFe of 1.0–1.5 nmol/kg near 2,000 m depth (0.4–0.9 nmol/kg above typical deep-sea dFe concentrations) was determined to be <span class="hlt">hydrothermally</span> derived based on its correlation with primordial 3He and dissolved Mn (dFe:3He of 0.9–2.7 × 106). Given the known <span class="hlt">sites</span> of <span class="hlt">hydrothermal</span> venting in these regions, this dFe must have been transported thousands of kilometers away from its vent <span class="hlt">site</span> to reach our sampling stations. Additionally, changes in the size partitioning of the <span class="hlt">hydrothermal</span> dFe between soluble (<0.02 µm) and colloidal (0.02–0.4 µm) phases with increasing distance from the vents indicate that dFe transformations continue to occur far from the vent source. This study confirms that although the southern East Pacific Rise only leaks 0.02–1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that <span class="hlt">hydrothermal</span> vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input). PMID:25349389</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.V21D0755M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V21D0755M"><span id="translatedtitle">Emission of CO2 from seafioor <span class="hlt">hydrothermal</span> systems at Mariana Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maeda, Y.; Shitashima, K.</p> <p>2007-12-01</p> <p><span class="hlt">Hydrothermal</span> vent fluids are highly enriched in CO2 and the CO2 rich fluids are released into the ocean as a <span class="hlt">hydrothermal</span> plume. Especially, the emission of <span class="hlt">hydrothermal</span>-related liquid CO2 from the seafloor (about 1500m) was discovered at the Okinawa Trough and Mariana Trough. At these areas, it is considered that the liquid CO2 rises up to shallow depth as a CO2 droplet and that the rising CO2 droplet dissolves gradually in ambient seawater. The observation of the <span class="hlt">hydrothermal</span>-related CO2 would provide the opportunity for understanding the physic-chemical behavior and diffusion process of liquid CO2 in the ocean. Newly developed in-situ pH/pCO2 sensor can detect precisely and rapidly the changes of pH and pCO2 derived from high CO2 concentration. At southern Mariana Trough, the pH/pCO2 sensor was installed onto the manned submersible and in-situ pH and pCO2 data were measured every 10 seconds during the operation on the <span class="hlt">hydrothermal</span> active <span class="hlt">site</span>. Mapping survey of low pH and pCO2 distribution was performed on the <span class="hlt">hydrothermal</span> active <span class="hlt">site</span> by the grid navigation of the manned submersible that installed the pH/pCO2 sensor. The results of pH mapping survey showed only localized pH depression at the <span class="hlt">hydrothermal</span> active <span class="hlt">site</span>. At NW Eifuku submarine volcano, <span class="hlt">hydrothermal</span>-related liquid CO2 dispersion was observed by using a towing multi-layer monitoring system. This system can observe the dispersion behavior of CO2 by towing several in-situ pH/pCO2 sensors and SSBL transponders in the high CO2 plume. Low pH plume of 100m high and 200m wide was detected above the summit of NW Eifuku submarine volcano.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25349389','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25349389"><span id="translatedtitle">Distal transport of dissolved <span class="hlt">hydrothermal</span> iron in the deep South Pacific Ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fitzsimmons, Jessica N; Boyle, Edward A; Jenkins, William J</p> <p>2014-11-25</p> <p>Until recently, <span class="hlt">hydrothermal</span> vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because <span class="hlt">hydrothermal</span> Fe was believed to precipitate quantitatively near the vent <span class="hlt">site</span>. Based on recent abyssal dFe enrichments near <span class="hlt">hydrothermal</span> vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209-212] argues that some <span class="hlt">hydrothermal</span> Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (<0.4 µm) measurements from the abyssal southeast and southwest Pacific Ocean, where dFe of 1.0-1.5 nmol/kg near 2,000 m depth (0.4-0.9 nmol/kg above typical deep-sea dFe concentrations) was determined to be <span class="hlt">hydrothermally</span> derived based on its correlation with primordial (3)He and dissolved Mn (dFe:(3)He of 0.9-2.7 × 10(6)). Given the known <span class="hlt">sites</span> of <span class="hlt">hydrothermal</span> venting in these regions, this dFe must have been transported thousands of kilometers away from its vent <span class="hlt">site</span> to reach our sampling stations. Additionally, changes in the size partitioning of the <span class="hlt">hydrothermal</span> dFe between soluble (<0.02 µm) and colloidal (0.02-0.4 µm) phases with increasing distance from the vents indicate that dFe transformations continue to occur far from the vent source. This study confirms that although the southern East Pacific Rise only leaks 0.02-1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that <span class="hlt">hydrothermal</span> vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.431..173E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.431..173E"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, P.-M.; Ballu, V.</p> <p>2015-12-01</p> <p>We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of <span class="hlt">hydrothermal</span> activity. We have identified a new on-axis <span class="hlt">site</span> with diffuse flow, Ewan, and an active vent structure ∼1.2 km from the axis, Capelinhos. These <span class="hlt">sites</span> are minor relative to the Main field, and our total heatflux estimate for all active <span class="hlt">sites</span> (200-1200 MW) is only slightly higher than previously published estimates. We also identify fossil <span class="hlt">sites</span> W of the main Lucky Strike field. A circular feature ∼200 m in diameter located on the flanks of a rifted off-axis central volcano is likely a large and inactive <span class="hlt">hydrothermal</span> edifice, named Grunnus. We find no indicator of focused <span class="hlt">hydrothermal</span> activity elsewhere along the segment, suggesting that the enhanced melt supply and the associated melt lenses, required to form central volcanoes, also sustain <span class="hlt">hydrothermal</span> circulation to form and maintain large and long-lived <span class="hlt">hydrothermal</span> fields. <span class="hlt">Hydrothermal</span> discharge to the seafloor occurs along fault traces, suggesting focusing of <span class="hlt">hydrothermal</span> circulation in the shallow crust along permeable fault zones.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS41C1835Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS41C1835Y"><span id="translatedtitle">Boron isotope systematics of <span class="hlt">hydrothermal</span> fluids from submarine <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamaoka, K.; Hong, E.; Ishikawa, T.; Gamo, T.; Kawahata, H.</p> <p>2013-12-01</p> <p>Boron is highly mobile in submarine <span class="hlt">hydrothermal</span> systems and useful to trace the process of water-rock reaction. In this study, we measured the boron content and isotopic composition of vent fluids collected from arc-backarc <span class="hlt">hydrothermal</span> systems in the western Pacific. In sediment-starved <span class="hlt">hydrothermal</span> systems (Manus Basin, Suiyo Seamount, and Mariana Trough), the boron content and isotopic composition of vent fluids are dependent on type of host rock. The end member fluids from MORB-like basalt-hosted Vienna Woods in the Manus Basin showed low boron content and high δ11B value (0.53 mM, 29.8‰), while dacite-hosted PACMANUS and the Suiyo Seamount showed high boron contents and low δ11B values (1.45 and 1.52 mM, 13.6 and 18.5‰, respectively). The Alice Springs and Forecast Vent field in the Mariana Trough showed values intermediate between them (0.72 and 0.63 mM, 19.9 and 24.0‰, respectively), reflecting reaction of seawater and basalt influenced by slab material. In phase separated <span class="hlt">hydrothermal</span> systems (North Fiji Basin), boron content and isotopic composition of vent fluids (0.44-0.56 mM, 34.5-35.9‰) were similar to those in the Vienna Woods. Considering little fractionation of boron and boron isotope during phase separation demonstrated by the previous experimental studies, it is suggested that the host rock in the North Fiji Basin is MORB-like basalt. In sediment-hosted <span class="hlt">hydrothermal</span> system (Okinawa Trough), the reaction with boron-enriched sediment following seawater-rock reaction resulted in significantly high boron contents and low δ11B values of vent fluids (4.4-5.9 mM, 1.5-2.6‰). The water-sediment ratio was estimated to be ~2. In spite of the different geological settings, the end member fuids from all vent fields are enriched in B relative to seawater (0.41 mM, 39.6‰) and the δ11B values are inversely propotional to the boron concentrations. It suggests that boron isotopic composition of vent fluid predominantly depends on the amount of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992EOSTr..73..233M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992EOSTr..73..233M"><span id="translatedtitle">Magmatic contributions to <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muffler, L. J. Patrick; Hedenquist, Jeffrey W.; Kesler, Stephen E.; Izawa, Eiji</p> <p></p> <p>Although there is agreement that many <span class="hlt">hydrothermal</span> systems in the upper crust derive their thermal energy from magmas, debate continues over the extent to which magmas contribute water, metals, and sulfur to <span class="hlt">hydrothermal</span> systems. A multidisciplinary seminar was held November 10-16, 1991, in Ebino and Kagoshima, Japan, to establish current understanding about this topic and to explore the major unanswered questions and the most promising research directions. The thirty-eight participants were from Japan (eighteen), the U.S. (thirteen), Canada and New Zealand (two each), and England, the Philippines, and Russia (one each). Disciplines represented were volcanology, geochemistry (volcanic-gas, water, isotopes, experimental, and modeling), igneous petrology, geothermal geology, economic geology, fluid-inclusion study, geophysics, and physical modeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13A1699M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1699M"><span id="translatedtitle">Structure of a seafloor <span class="hlt">hydrothermal</span> system in volcanic sediment: distribution of <span class="hlt">hydrothermal</span> clay minerals, at the Iheya North Knoll, Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miyoshi, Y.; Ishibashi, J.; Faure, K.; Uehara, S.</p> <p>2012-12-01</p> <p>Detailed investigation of clay minerals in <span class="hlt">hydrothermal</span> fields provides fundamental information for understanding the physical and geochemical conditions within a <span class="hlt">hydrothermal</span> system. Moreover, stable isotope geochemistry of clay minerals provides constraints on formation temperature. We investigated the distribution of clay minerals by XRD and TEM-EDS in a seafloor <span class="hlt">hydrothermal</span> field at Iheya North Knoll in the Okinawa Trough, using cored sediment obtained from the Integrated Ocean Drilling Program (IODP) Expedition 331. The chemical composition and isotope values of the representative clay minerals were analyzed to obtain information on the <span class="hlt">hydrothermal</span> system beneath the seafloor. Vertically, two different clay mineral facies are present. The boundary between the facies was identified at 6 mbsf (meters below the seafloor) at <span class="hlt">Site</span> C0013 (100 m east of <span class="hlt">hydrothermal</span> mound) and at 23 mbsf at <span class="hlt">Site</span> C0014 (450 m east of the mound). In the lower facies (6 - 28 mbsf and 45 mbsf at <span class="hlt">Site</span> C0013, 23 - 114 mbsf at <span class="hlt">Site</span> C0014), Mg-chlorite and/or Mg-chlorite-smectite mixed layer minerals are dominant. They are associated with sericite in deeper parts (45 mbsf at <span class="hlt">Site</span> C0013 and 38 - 114 mbsf at <span class="hlt">Site</span> C0014). The δ18O values of the clays range from +1.5 to +4.7 ‰ (VSMOW) and the formation temperatures of the Mg-chlorite are estimated to be 230 - 300 °C, assuming a value from 0 to +1.5 ‰ for δ18Owater. The original sediment in the Iheya North Knoll is considered to have been volcanic of felsic chemical composition, so alteration to Mg-rich chlorite would require supply of substantial amount of Mg. Abundant formation of Mg-chlorite is attributed to mixing of <span class="hlt">hydrothermal</span> fluid and seawater. In the upper facies at both <span class="hlt">sites</span>, Al-rich clay minerals (kaolinite and montmorillonite) dominate. The δ18O values of clays range between +9.6 and +13.3 ‰ and formation temperatures are estimated to range between 120 - 160 °C. As kaolinite formation is favorable under acidic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeCoA..75.2777K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.2777K"><span id="translatedtitle">Sulfur speciation in natural <span class="hlt">hydrothermal</span> waters, Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaasalainen, Hanna; Stefánsson, Andri</p> <p>2011-05-01</p> <p>The speciation of aqueous dissolved sulfur was determined in <span class="hlt">hydrothermal</span> waters in Iceland. The waters sampled included hot springs, acid-sulfate pools and mud pots, sub-boiling well discharges and two-phase wells. The water temperatures ranged from 4 to 210 °C, the pH T was between 2.20 and 9.30 at the discharge temperature and the SO 4 and Cl concentrations were 0.020-52.7 and <0.01-10.0 mmol kg -1, respectively. The analyses were carried out on-<span class="hlt">site</span> within ˜10 min of sampling using ion chromatography (IC) for sulfate (SO 42-), thiosulfate (S 2O 32-) and polythionates (S xO 62-) and titration and/or colorimetry for total dissolved sulfide (S 2-). Sulfite (SO 32-) could also be determined in a few cases using IC. Alternatively, for few samples in remote locations the sulfur oxyanions were stabilized on a resin on <span class="hlt">site</span> following elution and analysis by IC in the laboratory. Dissolved sulfate and with few exceptions also S 2- were detected in all samples with concentrations of 0.02-52.7 mmol kg -1 and <1-4100 μmol kg -1, respectively. Thiosulfate was detected in 49 samples of the 73 analyzed with concentrations in the range of <1-394 μmol kg -1 (S-equivalents). Sulfite was detected in few samples with concentrations in the range of <1-3 μmol kg -1. Thiosulfate and SO 32- were not detected in <100 °C well waters and S 2O 32- was observed only at low concentrations (<1-8 μmol kg -1) in ˜200 °C well waters. In alkaline and neutral pH hot springs, S 2O 32- was present in significant concentrations sometimes corresponding to up to 23% of total dissolved sulfur (S TOT). In steam-heated acid-sulfate waters, S 2O 32- was not a significant sulfur species. The results demonstrate that S 2O 32- and SO 32- do not occur in the deeper parts of <150 °C <span class="hlt">hydrothermal</span> systems and only in trace concentrations in ˜200-300 °C systems. Upon ascent to the surface and mixing with oxygenated ground and surface waters and/or dissolution of atmospheric O 2, S 2- is degassed and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T31A0478S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T31A0478S"><span id="translatedtitle">Aqueous Volatiles in Lau Basin <span class="hlt">Hydrothermal</span> Fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seewald, J.; McCollom, T.; Proskurowski, G.; Reeves, E.; Mottl, M.; Sharkey, J.; Wheat, C. G.; Tivey, M.</p> <p>2005-12-01</p> <p>The Lau Basin is a back-arc spreading center characterized by widespread <span class="hlt">hydrothermal</span> activity. High and low temperature vent fluids were collected from six vent fields along the Eastern Lau Spreading Center (ELSC) and the Valu Fa Ridge (VFR) using isobaric gas-tight samplers during R/V Melville cruise TUIM05MV. Fluids were analyzed for the abundances of H2, H2S, CH4, CO2, and CO to assess chemical environments inhabited by biological vent communities and constrain fluid-rock reactions and magmatic processes in subsurface environments. Maximum measured temperatures for focused venting in these areas varied from 309 to 363°C. Water depths decreased from ~2700m for <span class="hlt">sites</span> sampled at the northern end of the ELSC to ~1725m for the southern most <span class="hlt">site</span> sampled on the VFR. Endmember concentrations of dissolved H2 at the Kilo Moana, TowCam, and ABE vent fields on the ELSC varied from 0.054 to 0.498 mmol/l and showed a systematic interfield decrease from north to south along the ridge crest. A similar spatial trend was observed for endmember H2S concentrations that varied from 2.6 to 6.6 mmol/l. In contrast to H2 and H2S, aqueous CH4 abundances that varied from 0.028 to 0.057 mmol/l increased from north to south. In general, fluids from the Tui Malila, Mariner, and Vai Lili vent fields on the VFR showed greater compositional variability than fluids venting along the ELSC and an absence of systematic along strike chemical trends. Endmember H2, H2S, and CH4 abundances at VFR ranged from 0.0029 to 0.178 mmol/l, 0.010 to 9.6 mmol/l, and 0.0029 to 0.043 mmol/l, respectively. Endmember concentrations of dissolved CO at ELSC and VFR varied from 0.01 to 0.1 umol/l and showed systematic variations with dissolved H2 and CO2 abundances. Assessment of the CO, CO2, and H2 concentrations within a thermodynamic framework suggests that these species have attained equilibrium states at measured vent temperatures and pressures. The higher degree of compositional variability observed in vents</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DSRI..116..118K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DSRI..116..118K"><span id="translatedtitle">Geochemical characteristics of sinking particles in the Tonga arc <span class="hlt">hydrothermal</span> vent field, southwestern Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Hyung Jeek; Kim, Jonguk; Pak, Sang Joon; Ju, Se-Jong; Yoo, Chan Min; Kim, Hyun Sub; Lee, Kyeong Yong; Hwang, Jeomshik</p> <p>2016-10-01</p> <p>Studies of sinking particles associated with <span class="hlt">hydrothermal</span> vent fluids may help us to quantify mass transformation processes between <span class="hlt">hydrothermal</span> vent plumes and deposits. Such studies may also help us understand how various types of <span class="hlt">hydrothermal</span> systems influence particle flux and composition. However, the nature of particle precipitation out of <span class="hlt">hydrothermal</span> vent plumes in the volcanic arcs of convergent plate boundaries has not been well studied, nor have the characteristics of such particles been compared with the characteristics of sinking particles at divergent boundaries. We examined sinking particles collected by sediment traps for about 10 days at two <span class="hlt">sites</span>, each within 200 m of identified <span class="hlt">hydrothermal</span> vents in the south Tonga arc of the southwestern Pacific. The total mass flux was several-fold higher than in the non-<span class="hlt">hydrothermal</span> southwest tropical Pacific. The contribution of non-biogenic materials was dominant (over 72%) and the contribution of metals such as Fe, Mn, Cu, and Zn was very high compared to their average levels in the upper continental crust. The particle flux and composition indicate that <span class="hlt">hydrothermal</span> authigenic particles are the dominant source of the collected sinking particles. Overall, our elemental ratios are similar to observations of particles at the divergent plate boundary in the East Pacific Rise (EPR). Thus, the nature of the <span class="hlt">hydrothermal</span> particles collected in the south Tonga arc is probably not drastically different from particles in the EPR region. However, we observed consistent differences between the two <span class="hlt">sites</span> within the Tonga arc, in terms of the contribution of non-biogenic material, the radiocarbon content of sinking particulate organic carbon, the ratios of iron to other metals (e.g. Cu/Fe and Zn/Fe), and plume maturity indices (e.g. S/Fe). This heterogeneity within the Tonga arc is likely caused by differences in physical environment such as water depth, phase separation due to subcritical boiling and associated sub</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/543373','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/543373"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> vents is Lake Tanganyika, East African Rift system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tiercelin, J.J.; Pflumio, C.; Castrec, M.</p> <p>1993-06-01</p> <p>Sublacustrine <span class="hlt">hydrothermal</span> vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found <span class="hlt">hydrothermal</span> vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 {degrees}C were measured in <span class="hlt">hydrothermal</span> fluids and sediments. Veins of massive sulfides 1-10 cm thick (pyrite and marcasite banding) were found associated with vents at the Pemba <span class="hlt">site</span>. At Cape Banza, active vents are characterized by 1-70-cm-high aragonite chimneys, and there are microcrystalline pyrite coatings on the walls of <span class="hlt">hydrothermal</span> pipes. <span class="hlt">Hydrothermal</span> fluid end members show distinctive compositions at the two <span class="hlt">sites</span>. The Pemba end member is a NaHCO{sub 3}-enriched fluid similar to the NaHCO{sub 3} thermal fluids form lakes Magadi and Bogoria in the eastern branch of the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction of 219 and 179 {degrees}C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130{degrees}N normal-dextral faults that intersect the north-south major rift trend. The sources of heat for such <span class="hlt">hydrothermal</span> systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza. 21 refs., 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.T23A1880N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.T23A1880N"><span id="translatedtitle">An exploration for <span class="hlt">hydrothermal</span> plume evolution using the AUV "URASHIMA" with fluid sampling system at southern Mariana Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Noguchi, T.; Sunamura, M.; Yamamoto, H.; Fukuba, T.; Okino, K.; Sugiyama, T.; Okamura, K.</p> <p>2009-12-01</p> <p><span class="hlt">Hydrothermal</span> fluids contain high concentration of anoxic chemical species, i.e. methane and hydrogen sulfide, helium-3, and heavy metals derived from the rock-water interaction. During the hydothermal plume spreading, it is known that several chemical species are oxidized which include available energy source for microorganism, however, few results have been reported on the spatial variation of both of chemical and microbiological concentration and species. In the southern Mariana Trough, some <span class="hlt">site</span> surveys have been conducted with CTD hydrocasts, the manned submersible, and ROVs since 2003. In this field, three <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> were discovered within the small area, where the chemistry of each <span class="hlt">hydrothermal</span> fluid was different from each other. These differences of chemistry are prospected to affect the individual plume evolution. In order to discuss the each <span class="hlt">hydrothermal</span> plume evolution, we conducted high-resolution plume mapping by the AUV "URASHIMA" with some chemical sensors. Additionally, we loaded 24 bottles of water sampler for the geochemical and microbial analysis. During this cruise, we detected <span class="hlt">hydrothermal</span> plume anomalies derived from each <span class="hlt">hydrothermal</span> <span class="hlt">site</span> with the highly precise topographic results. Based on the results, we will discuss the relationships between the spreading of <span class="hlt">hydrothermal</span> plume (geochemical evolution) and the ecology of plume microbes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GGG.....7.5002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GGG.....7.5002B"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> mineral deposits and fossil biota from a young (0.1 Ma) abyssal hill on the flank of the fast spreading East Pacific Rise: Evidence for pulsed <span class="hlt">hydrothermal</span> flow and tectonic tapping of axial heat and fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benjamin, Sara B.; Haymon, Rachel M.</p> <p>2006-05-01</p> <p>Heat flow data indicate that most <span class="hlt">hydrothermal</span> heat loss from ocean lithosphere occurs on the flanks of the mid-ocean ridge, but few ridge flank <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> are known. We describe the first nonseamount, abyssal hill <span class="hlt">hydrothermal</span> mineral deposits to be recovered from the fast spreading East Pacific Rise (EPR) flanks. Deposits were sampled at two <span class="hlt">sites</span> on an abyssal hill ˜5 km east of the EPR axis, just north of Clipperton Fracture Zone at 10°20'N, on ˜0.1 Ma lithosphere. "Tevnia <span class="hlt">Site</span>" is on the axis-facing fault scarp of the hill, and "Ochre <span class="hlt">Site</span>" is located ˜950 m farther east near the base of the outward-facing slope. Clusters of fragile, biodegradable Tevnia worm tubes at both <span class="hlt">sites</span> indicate that <span class="hlt">hydrothermal</span> fluids carried sufficient H2S to sustain Tevnia worms, and that fluid flow waned too recently to allow time for tube destruction. Presence of microbial mats and other biota also are consistent with recent waning of flow. The deposits are mineralogically zoned, from nontronite-celadonite to hydrous Fe-oxide+opaline silica to Mn-oxide (birnessite and todorokite). This places them into a distinctive class of Fe-Si-Mn <span class="hlt">hydrothermal</span> deposits found along tectonic cracks and faults in young oceanic crust, and suggests that (1) deposits precipitated along an O2 gradient between ambient seawater and <span class="hlt">hydrothermal</span> fluid; (2) fluid temperatures were <150°C and (3) undiluted fluids were Mg-depleted, and Fe-, K-, Si- and Mn-enriched. These fluids may derive from high temperature seawater-basalt interaction ± phase separation proximal to the axial melt zone, and lose Cu and Zn before venting due to conductive cooling and/or pH increase. Ochre <span class="hlt">Site</span> samples are purely <span class="hlt">hydrothermal</span>; however, Tevnia <span class="hlt">Site</span> samples incorporate volcanic, sedimentary, and fossil components, and exhibit at least three generations of fracturing and <span class="hlt">hydrothermal</span> cementation. The Tevnia <span class="hlt">Site</span> breccias accumulated on the exposed fault scarp, possibly during multiple slip events and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998DSRII..45..319V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998DSRII..45..319V"><span id="translatedtitle">Naked in toxic fluids: A nudibranch mollusc from <span class="hlt">hydrothermal</span> vents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valdés, Ángel; Bouchet, Philippe</p> <p>1998-01-01</p> <p>A new species of the nudibranch genus Dendronotus (Mollusca, Opisthobranchia) is reported from a <span class="hlt">hydrothermal</span> vent at the Lucky Strike area, on the Mid-Atlantic Ridge. This is the first species of nudibranch recorded with certainty from a vent <span class="hlt">site</span>. Other species of Dendronotus are distributed in temperate waters on the continental shelf of the northern hemisphere. Two factors that probably account for the occurrence of a nudibranch in this <span class="hlt">hydrothermal</span> field are that the Lucky Strike area presents potential hydroid prey, and that nudibranchs apparently inhabit a lower activity area. It is hypothesized that the new species, which lacks eyes, is a permanent resident of vent fields on the Mid-Atlantic Ridge, but is probably not restricted to that environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4491839','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4491839"><span id="translatedtitle">Sustainability and dynamics of outcrop-to-outcrop <span class="hlt">hydrothermal</span> circulation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Winslow, Dustin M.; Fisher, Andrew T.</p> <p>2015-01-01</p> <p>Most seafloor <span class="hlt">hydrothermal</span> circulation occurs far from the magmatic influence of mid-ocean ridges, driving large flows of water, heat and solutes through volcanic rock outcrops on ridge flanks. Here we create three-dimensional simulations of ridge–flank <span class="hlt">hydrothermal</span> circulation, flowing between and through seamounts, to determine what controls hydrogeological sustainability, flow rate and preferred flow direction in these systems. We find that sustaining flow between outcrops that penetrate less-permeable sediment depends on a contrast in transmittance (the product of outcrop permeability and the area of outcrop exposure) between recharging and discharging <span class="hlt">sites</span>, with discharge favoured through less-transmissive outcrops. Many simulations include local discharge through outcrops at the recharge end of an outcrop-to-outcrop system. Both of these characteristics are observed in the field. In addition, smaller discharging outcrops sustain higher flow rates than larger outcrops, which may help to explain how so much lithospheric heat is extracted globally by this process. PMID:26113260</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26113260','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26113260"><span id="translatedtitle">Sustainability and dynamics of outcrop-to-outcrop <span class="hlt">hydrothermal</span> circulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Winslow, Dustin M; Fisher, Andrew T</p> <p>2015-01-01</p> <p>Most seafloor <span class="hlt">hydrothermal</span> circulation occurs far from the magmatic influence of mid-ocean ridges, driving large flows of water, heat and solutes through volcanic rock outcrops on ridge flanks. Here we create three-dimensional simulations of ridge-flank <span class="hlt">hydrothermal</span> circulation, flowing between and through seamounts, to determine what controls hydrogeological sustainability, flow rate and preferred flow direction in these systems. We find that sustaining flow between outcrops that penetrate less-permeable sediment depends on a contrast in transmittance (the product of outcrop permeability and the area of outcrop exposure) between recharging and discharging <span class="hlt">sites</span>, with discharge favoured through less-transmissive outcrops. Many simulations include local discharge through outcrops at the recharge end of an outcrop-to-outcrop system. Both of these characteristics are observed in the field. In addition, smaller discharging outcrops sustain higher flow rates than larger outcrops, which may help to explain how so much lithospheric heat is extracted globally by this process. PMID:26113260</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011283','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011283"><span id="translatedtitle">SHALLOW <span class="hlt">HYDROTHERMAL</span> SYSTEM AT NEWBERRY VOLCANO, OREGON: A CONCEPTUAL MODEL.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sammel, Edward A.</p> <p>1983-01-01</p> <p>Investigations at Newberry Volcano, Oregon, have resulted in a satisfactory account of the shallow <span class="hlt">hydrothermal</span> system, but have not indicated the nature of a possible geothermal reservoir. Hot springs in the caldera probably represent the return of circulating meteoric water, warmed at shallow depths by high conductive heat flow and by steam rising from greater depths. Ground-water recharge to the <span class="hlt">hydrothermal</span> system is at most 250 liters per second, of which about 20 liters per second reappears in the hot springs. Analysis of temperature anomalies in a Geological Survey drillhole indicates that ground-water flow totaling about 125 liters per second could be moving laterally at depths of less than 650 m at the drill <span class="hlt">site</span>. Refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26113260','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26113260"><span id="translatedtitle">Sustainability and dynamics of outcrop-to-outcrop <span class="hlt">hydrothermal</span> circulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Winslow, Dustin M; Fisher, Andrew T</p> <p>2015-06-26</p> <p>Most seafloor <span class="hlt">hydrothermal</span> circulation occurs far from the magmatic influence of mid-ocean ridges, driving large flows of water, heat and solutes through volcanic rock outcrops on ridge flanks. Here we create three-dimensional simulations of ridge-flank <span class="hlt">hydrothermal</span> circulation, flowing between and through seamounts, to determine what controls hydrogeological sustainability, flow rate and preferred flow direction in these systems. We find that sustaining flow between outcrops that penetrate less-permeable sediment depends on a contrast in transmittance (the product of outcrop permeability and the area of outcrop exposure) between recharging and discharging <span class="hlt">sites</span>, with discharge favoured through less-transmissive outcrops. Many simulations include local discharge through outcrops at the recharge end of an outcrop-to-outcrop system. Both of these characteristics are observed in the field. In addition, smaller discharging outcrops sustain higher flow rates than larger outcrops, which may help to explain how so much lithospheric heat is extracted globally by this process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2017E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2017E"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, P. M.; Ballu, V.</p> <p>2015-12-01</p> <p>We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment to evaluate the distribution of <span class="hlt">hydrothermal</span> activity. The Lucky Strike segment hosts three active <span class="hlt">hydrothermal</span> fields: Capelinhos, Ewan, and the known Main Lucky Strike <span class="hlt">Hydrothermal</span> Field (MLSHF). Capelinhos is located 1.3 km E of the axis and the MLSHF, and consists of a ~20 m sulfide mound with black smoker vents. Ewan is located ~1.8 km south from the MLSHF along the axial graben, and displays only diffuse flow along and around scarps of collapse structures associated with fault scarps. At the MLSHF we have identified an inactive <span class="hlt">site</span>, thus broadening the extent of this field. Heat flux estimates from these new <span class="hlt">sites</span> are relatively low and correspond to ~10% of the heat flux estimated for the Main field, with an integrated heatflux of 200-1200 MW. Overall, most of the flux (up to 80-90%) is associated with diffuse outflow, with the Ewan <span class="hlt">site</span> showing solely diffuse flow and Capelinhos mostly focused flow. Microbathymetry also reveals a large, off-axis (~2.4 km) <span class="hlt">hydrothermal</span> field, similar to the TAG mound in size, on the flanks of a rifted volcano. The association of these fields to a central volcano, and the absence of indicators of <span class="hlt">hydrothermal</span> activity along the ridge segment, suggest that sustained <span class="hlt">hydrothermal</span> activity is maintained by the enhanced melt supply and the associated magma chamber(s) required to build central volcanoes. <span class="hlt">Hydrothermal</span> outflow zones at the seafloor are systematically controlled by faults, indicating that <span class="hlt">hydrothermal</span> circulation in the shallow crust exploits permeable fault zones. Central volcanoes are thus associated with long-lived <span class="hlt">hydrothermal</span> activity, and these <span class="hlt">sites</span> may play a major role in the distribution and biogeography of vent communities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS23A1166P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS23A1166P"><span id="translatedtitle">Diffused vs. Focused Flow - Metaproteogenomic Insights into Effects of <span class="hlt">Hydrothermal</span> Fluid Flow on Metal-Sulfide Chimney Colonizing Biofilms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pjevac, P.; Markert, S.; Richter, M.; Gruber-Vodicka, H.; Schweder, T.; Amann, R.; Meyerdierks, A.</p> <p>2014-12-01</p> <p>At many <span class="hlt">sites</span> of <span class="hlt">hydrothermal</span> discharge in the deep-sea, the deposition of metal sulfides from <span class="hlt">hydrothermal</span> fluids leads to the formation of geological structures known as <span class="hlt">hydrothermal</span> chimneys. The mixing of reduced <span class="hlt">hydrothermal</span> fluids with oxygenated seawater leads to the formation of steep redox gradients within the chimney walls. These gradients facilitate the co-existence of metabolically diverse microorganisms in the narrow habitable zone of <span class="hlt">hydrothermal</span> chimney walls. However, the overall composition of chimney-associated microbial community is usually of low complexity and represents an environment suitable for metaomic-based studies. We used metagenomic and metaproteomic tools to compare microbial communities colonizing two metal-sulfide chimneys from the Manus Basin back-arc spreading center in the Bismarck Sea off Papua New Guinea. These chimneys were supplied by the same source <span class="hlt">hydrothermal</span> fluids, but exhibited different fluid flow regimes. One chimney (RMR5) had a focused venting edifice, while the other (RMR-D) displayed diffuse fluid efflux on its entire outer surface. Although the microbial diversity of both chimneys is similar and dominated by mesophilic Epsilonproteobacteria, our results indicate a strong structuring effect of <span class="hlt">hydrothermal</span> fluid flow regime on chimney-associated biofilms. The microbial community composition indicates a homogeneous colonization of the diffuse chimney walls. In contrast, the walls of the focused venting chimney appear to be colonized in layers reflecting different temperature tolerances of the dominant microorganisms. Sulfide-oxidation is likely the key metabolism in both chimneys, which is in line with the high sulfide content of the source <span class="hlt">hydrothermal</span> fluid. However, preliminary metaproteome analysis indicates high activity of low-abundant methanotrophic Bacteria in the diffuser chimney walls. This finding is particularly interesting in light of the very low methane content of the source <span class="hlt">hydrothermal</span> fluid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2023H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2023H"><span id="translatedtitle">The Interplay of Magmatic and <span class="hlt">Hydrothermal</span> Convection: Insights From Numerical Modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasenclever, J.; Rupke, L.; Morgan, J. P.; Galerne, C.</p> <p>2015-12-01</p> <p> (i.e. its fluxibility) make these warm regions more efficient for recharge flow than colder parts of the crust. Above local depressions of the AMC roof we observe less vigorous <span class="hlt">hydrothermal</span> flow, so that along-ridge variations in AMC depth could be linked to locations of <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT........40G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT........40G"><span id="translatedtitle">Magmatic intrusions and <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gulick, Virginia Claire</p> <p>1993-01-01</p> <p>This dissertation investigates the possible role of <span class="hlt">hydrothermally</span> driven ground-water outflow in the formation of fluvial valleys on Mars. Although these landforms have often been cited as evidence for a past warmer climate and denser atmosphere, recent theoretical modeling precludes such climatic conditions on early Mars when most fluvial valleys formed. Because fluvial valleys continued to form throughout Mars' geological history and the most Earth-like stream valleys on Mars formed well after the decline of the early putative Earth-like climate, it may be unnecessary to invoke drastically different climatic conditions for the formation of the earliest stream valleys. The morphology of most Martian fluvial valleys indicates formation by ground-water sapping which is consistent with a subsurface origin. Additionally, many Martian fluvial valleys formed on volcanoes, impact craters, near fractures, or adjacent to terrains interpreted as igneous intrusions; all are possible locales of vigorous, geologically long-lived <span class="hlt">hydrothermal</span> circulation. Comparison of Martian valley morphology to similar features on Earth constrains valley genesis scenarios. Volumes of measured Martian fluvial valleys range from 1010 to 1013 m3. Based on terrestrial analogs, total water volumes required to erode these valleys range from approximately 1010 to 1015 m3. The clustered distribution of Martian valleys within a given terrain type, the sapping dominated morphology, and the general lack of associated runoff valleys all indicate the importance of localized ground-water outflow in the formation of these fluvial systems. An analytic model of a conductively cooling cylindrical intrusion is coupled with the U.S. Geological Survey's numerical ground-water computer code SUTRA to evaluate the magnitude of ground-water outflow expected from magmatically-driven <span class="hlt">hydrothermal</span> systems on Mars. Results indicate that magmatic intrusions of several 102 km3 or larger can provide sufficient ground</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T43D2704F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T43D2704F"><span id="translatedtitle">Magnetic Structure of Backarc Spreading Axis with <span class="hlt">Hydrothermal</span> Vents; the Southern Mariana Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, M.; Okino, K.; Mochizuki, N.; Honsho, C.; Szitkar, F.; Dyment, J.; Nakamura, K.</p> <p>2012-12-01</p> <p>Seafloor <span class="hlt">hydrothermal</span> systems are important in relation to global heat and chemical fluxes as well as habitat of microbial communities. The substantial variation of <span class="hlt">hydrothermal</span> systems in various tectonic settings has important implications for the magnetic structure of oceanic crust. It has been very difficult to detect the geophysical signature of <span class="hlt">hydrothermal</span> systems from sea-surface data because the small scale of <span class="hlt">hydrothermal</span> systems is below the limit of resolution. The advance of near-bottom survey methods using a submersible, deep-tow, ROV and AUV has made possible high-resolution geophysical mapping around <span class="hlt">hydrothermal</span> areas. Near-bottom magnetic surveys can provide direct information on the magnetization of the shallower oceanic crust, implying <span class="hlt">hydrothermal</span> alteration both in active and fossil vent <span class="hlt">sites</span>. Near-bottom three component magnetic measurements on submersible Shinkai 6500 were carried out at <span class="hlt">hydrothermal</span> fields in the Southern Mariana Trough, a slow spreading backarc basin. Fourteen dive surveys were conducted during cruises YK11-10 and YK10-11. We investigated the magnetic structure of four <span class="hlt">hydrothermal</span> systems located at on- and off-axis to clarify how the geophysical and geological setting controls the fluid circulation at small scale. Recent researches at slow spreading ridges showed a relationship between crustal magnetic structure and host rock around <span class="hlt">hydrothermal</span> vents (e.g. Tivey and Dyment, 2010), but no observation at backarc spreading axis has been reported so far. We carefully corrected the effects of induced and permanent magnetizations of the submersible by applying the method of Isezaki [1986] with dumped least-square method (Honsho et al., 2009). After subtracting the IGRF from the corrected observed data, we obtained geomagnetic vector anomalies in geographical coordinate. For three transects of the axis, we applied three methods; 2D inversion technique (Parker and Huestis, 1972), 2D forward modeling technique (Honsho et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1076659','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1076659"><span id="translatedtitle">Whole Algae <span class="hlt">Hydrothermal</span> Liquefaction Technology Pathway</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Biddy, M.; Davis, R.; Jones, S.</p> <p>2013-03-01</p> <p>This technology pathway case investigates the feasibility of using whole wet microalgae as a feedstock for conversion via <span class="hlt">hydrothermal</span> liquefaction. Technical barriers and key research needs have been assessed in order for the <span class="hlt">hydrothermal</span> liquefaction of microalgae to be competitive with petroleum-derived gasoline-, diesel-, and jet-range hydrocarbon blendstocks.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22928928','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22928928"><span id="translatedtitle">Microbial community structure across fluid gradients in the Juan de Fuca Ridge <span class="hlt">hydrothermal</span> system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, Rika E; Beltrán, Mónica Torres; Hallam, Steven J; Baross, John A</p> <p>2013-02-01</p> <p>Physical and chemical gradients are dominant factors in shaping <span class="hlt">hydrothermal</span> vent microbial ecology, where archaeal and bacterial habitats encompass a range between hot, reduced <span class="hlt">hydrothermal</span> fluid and cold, oxidized seawater. To determine the impact of these fluid gradients on microbial communities inhabiting these systems, we surveyed bacterial and archaeal community structure among and between <span class="hlt">hydrothermal</span> plumes, diffuse flow fluids, and background seawater in several <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> on the Juan de Fuca Ridge using 16S rRNA gene diversity screening (clone libraries and terminal restriction length polymorphisms) and quantitative polymerase chain reaction methods. Community structure was similar between <span class="hlt">hydrothermal</span> plumes and background seawater, where a number of taxa usually associated with low-oxygen zones were observed, whereas high-temperature diffuse fluids exhibited a distinct phylogenetic profile. SUP05 and Arctic96BD-19 sulfur-oxidizing bacteria were prevalent in all three mixing regimes where they exhibited overlapping but not identical abundance patterns. Taken together, these results indicate conserved patterns of redox-driven niche partitioning between <span class="hlt">hydrothermal</span> mixing regimes and microbial communities associated with sinking particles and oxygen-deficient waters. Moreover, the prevalence of SUP05 and Arctic96BD-19 in plume and diffuse flow fluids indicates a more cosmopolitan role for these groups in the ecology and biogeochemistry of the dark ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoRL..3316607K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..3316607K"><span id="translatedtitle">Liquid CO2 venting on the seafloor: Yonaguni Knoll IV <span class="hlt">hydrothermal</span> system, Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Konno, Uta; Tsunogai, Urumu; Nakagawa, Fumiko; Nakaseama, Miwako; Ishibashi, Jun-ichiro; Nunoura, Takuro; Nakamura, Ko-ichi</p> <p>2006-08-01</p> <p>We determined the chemical and isotopic compositions of the liquid CO2 found on Yonaguni IV knoll <span class="hlt">hydrothermal</span> <span class="hlt">site</span>, as well as those in <span class="hlt">hydrothermal</span> fluid venting from the surrounding chimneys. The δ13C of both CO2 and CH4 in the liquid CO2 almost coincide with those in the <span class="hlt">hydrothermal</span> fluid, suggesting that the liquid CO2 must be derived from the <span class="hlt">hydrothermal</span> fluid. While showing homogeneous δ13C, the <span class="hlt">hydrothermal</span> fluids exhibit wide variation in gas contents. Active phase separation must be taking place within the conduits. Besides, H2-depletion in the liquid CO2 suggests formation of solid CO2-hydrate must also precede the venting of liquid CO2. In conclusion, liquid CO2 must be produced through following subseafloor processes: phase separation of <span class="hlt">hydrothermal</span> fluid due to boiling, formation of solid CO2-hydrate due to cooling of vapor phase, and melting of the solid CO2-hydrate to liquid CO2 due to a temperature increase within the sedimentary layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5163744','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5163744"><span id="translatedtitle">REE/Fe variations in <span class="hlt">hydrothermal</span> sediments: Implications for the REE content of seawater</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Olivarez, A.M.; Owen, R.M. )</p> <p>1989-03-01</p> <p>Seafloor <span class="hlt">hydrothermal</span> vent solutions exhibit rare earth element (REE) enrichments ranging between one to three orders of magnitude greater than average seawater. To assess the impact of these <span class="hlt">hydrothermal</span> inputs on ocean chemistry, the authors have examined he behavior of REEs for <span class="hlt">hydrothermal</span> sediments collected adjacent to two Pacific spreading ridge <span class="hlt">sites</span>: the East Pacific Rise at 19{degree}S, and the Southern Juan de Fuca Ridge at 45{degree}N. In general, the REE/Fe ratios for both proximal and distal <span class="hlt">hydrothermal</span> sediments are greater than vent solutions by a factor of 2 to 500, and these ratios increase with increasing distance away from the ridge axis. An evaluation of these results in the context of previous models of REE behavior indicates that, in fact, seawater experiences a net depletion in REEs as a result of <span class="hlt">hydrothermal</span> activity. This is due primarily to the large scavenging capacity of iron oxyhydroxides which precipitate from these solutions. Such an interpretation explains why the REE content of seawater collected in the vicinity of <span class="hlt">hydrothermal</span> vents is anomalously lower than normal seawater sampled from a comparable depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25762281','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25762281"><span id="translatedtitle">Ongoing <span class="hlt">hydrothermal</span> activities within Enceladus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hsu, Hsiang-Wen; Postberg, Frank; Sekine, Yasuhito; Shibuya, Takazo; Kempf, Sascha; Horányi, Mihály; Juhász, Antal; Altobelli, Nicolas; Suzuki, Katsuhiko; Masaki, Yuka; Kuwatani, Tatsu; Tachibana, Shogo; Sirono, Sin-iti; Moragas-Klostermeyer, Georg; Srama, Ralf</p> <p>2015-03-12</p> <p>Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick. These findings imply rock-water interactions in regions surrounding the core of Enceladus. The resulting chemical 'footprints' are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft. Here we report an analysis of silicon-rich, nanometre-sized dust particles (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus' subsurface waters and released by sputter erosion in Saturn's E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) <span class="hlt">hydrothermal</span> reactions associated with global-scale geothermal activity that quickly transports <span class="hlt">hydrothermal</span> products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus. PMID:25762281</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25762281','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25762281"><span id="translatedtitle">Ongoing <span class="hlt">hydrothermal</span> activities within Enceladus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hsu, Hsiang-Wen; Postberg, Frank; Sekine, Yasuhito; Shibuya, Takazo; Kempf, Sascha; Horányi, Mihály; Juhász, Antal; Altobelli, Nicolas; Suzuki, Katsuhiko; Masaki, Yuka; Kuwatani, Tatsu; Tachibana, Shogo; Sirono, Sin-iti; Moragas-Klostermeyer, Georg; Srama, Ralf</p> <p>2015-03-12</p> <p>Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick. These findings imply rock-water interactions in regions surrounding the core of Enceladus. The resulting chemical 'footprints' are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft. Here we report an analysis of silicon-rich, nanometre-sized dust particles (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus' subsurface waters and released by sputter erosion in Saturn's E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) <span class="hlt">hydrothermal</span> reactions associated with global-scale geothermal activity that quickly transports <span class="hlt">hydrothermal</span> products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993RvGeo..31..211L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993RvGeo..31..211L"><span id="translatedtitle">Ecology of deep-sea <span class="hlt">hydrothermal</span> vent communities: A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lutz, Richard A.; Kennish, Michael J.</p> <p>1993-08-01</p> <p>Studies of the many active and inactive <span class="hlt">hydrothermal</span> vents found during the past 15 years have radically altered views of biological and geological processes in the deep sea. The biological communities occupying the vast and relatively stable soft bottom habitats of the deep sea are characterized by low population densities, high species diversity, and low biomass. In contrast, those inhabiting the generally unstable conditions of <span class="hlt">hydrothermal</span> vent environments exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. Biological processes, such as rates of metabolism and growth, in vent organisms are comparable to those observed in organisms from shallow-water ecosystems. An abundant energy source is provided by chemosynthetic bacteria that constitute the primary producers sustaining the lush communities at the <span class="hlt">hydrothermal</span> <span class="hlt">sites</span>. Fluxes in vent flow and fluid chemistry cause changes in growth rates, reproduction, mortality, and/or colonization of vent fauna, leading to temporal and spatial variation of the vent communities. Vent populations that cannot adapt to modified flow rates are adversely affected, as is evidenced by high mortality or lower rates of colonization, growth, or reproduction. Substantial changes in biota have been witnessed at several vents, and successional cycles have been proposed for the Galapagos vent fields. Dramatic temporal and spatial variations in vent community structure may also relate to variations in larval dispersal and chance recruitment, as well as biotic interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/138865','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/138865"><span id="translatedtitle">Single-hole in situ thermal probe for <span class="hlt">hydrothermal</span> characterization at Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Danko, G.; Buscheck, T.A.</p> <p>1993-01-01</p> <p>The REKA thermal probe method, which uses a single borehole to measure in situ rock thermophysical properties and provides for efficient and low-cost <span class="hlt">site</span> characterization, is analyzed for its application to <span class="hlt">hydrothermal</span> system characterization. It is demonstrated throughout the evaluation of several temperature fields obtained for different thermal zones that the REKA method can be applied to simultaneously determine (1) two independent thermophysical properties, i.e., heat conductivity and thermal diffusivity and (2) a set of heat transport parameters, which can be used to characterize the behavior of a <span class="hlt">hydrothermal</span> system. Based on the direct physical meaning of these transport parameters, the components of the heat transport mechanism in a given time and location of the <span class="hlt">hydrothermal</span> system can be described. This evaluation can be applied to characterizing and quantifying in situ rock dry-out and condensate shedding at the proposed repository <span class="hlt">site</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V21A4722T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V21A4722T"><span id="translatedtitle">Geochemical Evidence for Recent <span class="hlt">Hydrothermal</span> Alteration of Marine Sediments in Mid-Okinawa Trough, Southwest Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tanaka, A.; Abe, G.; Yamaguchi, K. E.</p> <p>2014-12-01</p> <p>Recent studies have shown that submarine <span class="hlt">hydrothermal</span> system supports diverse microbial life. Bio-essential metals supporting such microbial communities were released from basalts by high-temperature water-rock interaction in deeper part of the oceanic crust and carried by submarine fluid flow. Its total quantity in global <span class="hlt">hydrothermal</span> settings has been estimated to be on the order of ~1019 g/yr, which is surprisingly on the same order of the total river flows (Urabe et al., 2011). Therefore, it is important to explore how submarine river system works, i.e., to understand mechanism and extent of elemental transport, which should lead to understanding of the roles of <span class="hlt">hydrothermal</span> circulation in oceanic crust in controlling elemental budget in the global ocean and geochemical conditions to support deep hot biosphere.  We performed REE analysis of marine sediments influenced by submarine <span class="hlt">hydrothermal</span> activity in Mid-Okinawa Trough. The sediment samples used in this study are from IODP <span class="hlt">site</span> at Iheya North region and JADE <span class="hlt">site</span> at Izena region. The samples show alternation between volcanic and clastic sediments. <span class="hlt">Hydrothermal</span> fluids of this area contain elevated concentrations of volatile components such as H2, CO2, CH4, NH4+, and H2S, supporting diverse chemoautotrophic microbial community (Nakagawa et al., 2005). The purpose of this study is to examine the effect of <span class="hlt">hydrothermal</span> activity on the REE signature of the sediments. Chondrite-normalized REE patterns of the samples show relative enrichment of light over heavy REEs, weak positive Ce anomalies, and variable degrees of negative Eu anomalies. The REE patterns suggest the sediments source was mainly basalt, suggesting insignificant input of continental materials. Negative Eu anomalies found in the IODP <span class="hlt">site</span> become more pronounced with increasing depth, suggesting progressive increase of <span class="hlt">hydrothermal</span> alteration where Eu was reductively dissolved into fluids by decomposition of feldspars. Contrary, at the JADE <span class="hlt">site</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3250503','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3250503"><span id="translatedtitle">Antarctic Marine Biodiversity and Deep-Sea <span class="hlt">Hydrothermal</span> Vents</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chown, Steven L.</p> <p>2012-01-01</p> <p>The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea <span class="hlt">hydrothermal</span> vents. Vent ecosystems have been documented from many <span class="hlt">sites</span> across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea <span class="hlt">hydrothermal</span> vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic <span class="hlt">hydrothermal</span> vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea <span class="hlt">hydrothermal</span> vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining. PMID:22235192</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17654787','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17654787"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> petroleum from lacustrine sedimentary organic matter in the East African Rift.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simoneit, B R; Aboul-Kassim, T A; Tiercelin, J J</p> <p>2000-03-01</p> <p>Cape Kalamba oil seeps occur at the south end of the Ubwari Peninsula, at the intersection of faults controlling the morphology of the northern basin of the Tanganyika Rift, East Africa. Oil samples collected at the surface of the lake 3-4 km offshore from Cape Kalamba have been studied. The aliphatic hydrocarbon and biomarker compositions, with the absence of the typical suite of polynuclear aromatic hydrocarbons, indicate an origin from <span class="hlt">hydrothermal</span> alteration of immature microbial biomass in the sediments. These data show a similarity between a tar sample from the beach and the petroleum from the oil seeps, and confirm that the source of these oils is from organic matter consisting mainly of bacterial and degraded algal biomass, altered by <span class="hlt">hydrothermal</span> activity. The compositions also demonstrate a < 200 degrees C temperature for formation/generation of this <span class="hlt">hydrothermal</span> petroleum, similar to the fluid temperature identified for the Pemba <span class="hlt">hydrothermal</span> <span class="hlt">site</span> located 150 km north of Cape Kalamba. The 14C age of 25.6 ka B.P. obtained for the tar ball suggests that Pleistocene lake sediments could be the source rock. <span class="hlt">Hydrothermal</span> generation may have occurred slightly before 25 ka B.P., during a dry climatic environment, when the lake level was lower than today. These results also suggest that the Cape Kalamba <span class="hlt">hydrothermal</span> activity did not occur in connection with an increased flux of meteoric water, higher water tables and lake levels as demonstrated in the Kenya Rift and for the Pemba <span class="hlt">site</span>. <span class="hlt">Hydrothermal</span> petroleum formation is a facile process also in continental rift systems and should be considered in exploration for energy resources in such locales. PMID:17654787</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17654787','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17654787"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> petroleum from lacustrine sedimentary organic matter in the East African Rift.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simoneit, B R; Aboul-Kassim, T A; Tiercelin, J J</p> <p>2000-03-01</p> <p>Cape Kalamba oil seeps occur at the south end of the Ubwari Peninsula, at the intersection of faults controlling the morphology of the northern basin of the Tanganyika Rift, East Africa. Oil samples collected at the surface of the lake 3-4 km offshore from Cape Kalamba have been studied. The aliphatic hydrocarbon and biomarker compositions, with the absence of the typical suite of polynuclear aromatic hydrocarbons, indicate an origin from <span class="hlt">hydrothermal</span> alteration of immature microbial biomass in the sediments. These data show a similarity between a tar sample from the beach and the petroleum from the oil seeps, and confirm that the source of these oils is from organic matter consisting mainly of bacterial and degraded algal biomass, altered by <span class="hlt">hydrothermal</span> activity. The compositions also demonstrate a < 200 degrees C temperature for formation/generation of this <span class="hlt">hydrothermal</span> petroleum, similar to the fluid temperature identified for the Pemba <span class="hlt">hydrothermal</span> <span class="hlt">site</span> located 150 km north of Cape Kalamba. The 14C age of 25.6 ka B.P. obtained for the tar ball suggests that Pleistocene lake sediments could be the source rock. <span class="hlt">Hydrothermal</span> generation may have occurred slightly before 25 ka B.P., during a dry climatic environment, when the lake level was lower than today. These results also suggest that the Cape Kalamba <span class="hlt">hydrothermal</span> activity did not occur in connection with an increased flux of meteoric water, higher water tables and lake levels as demonstrated in the Kenya Rift and for the Pemba <span class="hlt">site</span>. <span class="hlt">Hydrothermal</span> petroleum formation is a facile process also in continental rift systems and should be considered in exploration for energy resources in such locales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010GGG....11.5002J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010GGG....11.5002J&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> circulation within the Endeavour Segment, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, H. Paul; Tivey, Maurice A.; Bjorklund, Tor A.; Salmi, Marie S.</p> <p>2010-05-01</p> <p>Areas of the seafloor at mid-ocean ridges where <span class="hlt">hydrothermal</span> vents discharge are easily recognized by the dramatic biological, physical, and chemical processes that characterize such <span class="hlt">sites</span>. Locations where seawater flows into the seafloor to recharge <span class="hlt">hydrothermal</span> cells within the crustal reservoir are by contrast almost invisible but can be indirectly identified by a systematic grid of conductive heat flow measurements. An array of conductive heat flow stations in the Endeavour axial valley of the Juan de Fuca Ridge has identified recharge zones that appear to represent a nested system of fluid circulation paths. At the scale of an axial rift valley, conductive heat flow data indicate a general cross-valley fluid flow, where seawater enters the shallow subsurface crustal reservoir at the eastern wall of the Endeavour axial valley and undergoes a kilometer of horizontal transit beneath the valley floor, finally exiting as warm <span class="hlt">hydrothermal</span> fluid discharge on the western valley bounding wall. Recharge zones also have been identified as located within an annular ring of very cold seafloor around the large Main Endeavour <span class="hlt">Hydrothermal</span> Field, with seawater inflow occurring within faults that surround the fluid discharge <span class="hlt">sites</span>. These conductive heat flow data are consistent with previous models where high-temperature fluid circulation cells beneath large <span class="hlt">hydrothermal</span> vent fields may be composed of narrow vertical cylinders. Subsurface fluid circulation on the Endeavour Segment occurs at various crustal depths in three distinct modes: (1) general east to west flow across the entire valley floor, (2) in narrow cylinders that penetrate deeply to high-temperature heat sources, and (3) supplying low-temperature diffuse vents where seawater is entrained into the shallow uppermost crust by the adjacent high-temperature cylindrical systems. The systematic array of conductive heat flow measurements over the axial valley floor averaged ˜150 mW/m2, suggesting that only about 3% of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025764','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025764"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> and tectonic activity in northern Yellowstone Lake, Wyoming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Johnson, S.Y.; Stephenson, W.J.; Morgan, L.A.; Shanks, Wayne C.; Pierce, K.L.</p> <p>2003-01-01</p> <p>Yellowstone National Park is the <span class="hlt">site</span> of one of the world's largest calderas. The abundance of geothermal and tectonic activity in and around the caldera, including historic uplift and subsidence, makes it necessary to understand active geologic processes and their associated hazards. To that end, we here use an extensive grid of high-resolution seismic reflection profiles (???450 km) to document <span class="hlt">hydrothermal</span> and tectonic features and deposits in northern Yellowstone Lake. Sublacustrine geothermal features in northern Yellowstone Lake include two of the largest known <span class="hlt">hydrothermal</span> explosion craters, Mary Bay and Elliott's. Mary Bay explosion breccia is distributed uniformly around the crater, whereas Elliott's crater breccia has an asymmetric distribution and forms a distinctive, ???2-km-long, hummocky lobe on the lake floor. <span class="hlt">Hydrothermal</span> vents and low-relief domes are abundant on the lake floor; their greatest abundance is in and near explosion craters and along linear fissures. Domed areas on the lake floor that are relatively unbreached (by vents) are considered the most likely <span class="hlt">sites</span> of future large <span class="hlt">hydrothermal</span> explosions. Four submerged shoreline terraces along the margins of northern Yellowstone Lake add to the Holocene record or postglacial lake-level fluctuations attributed to "heavy breathing" of the Yellowstone magma reservoir and associated geothermal system. The Lake Hotel fault cuts through northwestern Yellowstone Lake and represents part of a 25-km-long distributed extensional deformation zone. Three postglacial ruptures indicate a slip rate of ???0.27 to 0.34 mm/yr. The largest (3.0 m slip) and most recent event occurred in the past ???2100 yr. Although high heat flow in the crust limits the rupture area of this fault zone, future earthquakes of magnitude ???5.3 to 6.5 are possible. Earthquakes and <span class="hlt">hydrothermal</span> explosions have probably triggered landslides, common features around the lake margins. Few high-resolution seismic reflection surveys have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.419..143G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.419..143G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Fe cycling and deep ocean organic carbon scavenging: Model-based evidence for significant POC supply to seafloor sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>German, C. R.; Legendre, L. L.; Sander, S. G.; Niquil, N.; Luther, G. W.; Bharati, L.; Han, X.; Le Bris, N.</p> <p>2015-06-01</p> <p>Submarine <span class="hlt">hydrothermal</span> venting has recently been identified to have the potential to impact ocean biogeochemistry at the global scale. This is the case because processes active in <span class="hlt">hydrothermal</span> plumes are so vigorous that the residence time of the ocean, with respect to cycling through <span class="hlt">hydrothermal</span> plumes, is comparable to that of deep ocean mixing caused by thermohaline circulation. Recently, it has been argued that seafloor venting may provide a significant source of bio-essential Fe to the oceans as the result of a close coupling between Fe and organic carbon in <span class="hlt">hydrothermal</span> plumes. But a complementary question remains to be addressed: does this same intimate Fe-Corg association in <span class="hlt">hydrothermal</span> plumes cause any related impact to the global C cycle? To address this, SCOR-InterRidge Working Group 135 developed a modeling approach to synthesize <span class="hlt">site</span>-specific field data from the East Pacific Rise 9°50‧ N <span class="hlt">hydrothermal</span> field, where the range of requisite data sets is most complete, and combine those inputs with global estimates for dissolved Fe inputs from venting to the oceans to establish a coherent model with which to investigate <span class="hlt">hydrothermal</span> Corg cycling. The results place new constraints on submarine Fe vent fluxes worldwide, including an indication that the majority of Fe supplied to <span class="hlt">hydrothermal</span> plumes should come from entrainment of diffuse flow. While this same entrainment is not predicted to enhance the supply of dissolved organic carbon to <span class="hlt">hydrothermal</span> plumes by more than ∼10% over background values, what the model does indicate is that scavenging of carbon in association with Fe-rich <span class="hlt">hydrothermal</span> plume particles should play a significant role in the delivery of particulate organic carbon to deep ocean sediments, worldwide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70111059','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70111059"><span id="translatedtitle">Dynamics of the Yellowstone <span class="hlt">hydrothermal</span> system</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hurwitz, Shaul; Lowenstern, Jacob B.</p> <p>2014-01-01</p> <p>The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a <span class="hlt">hydrothermal</span> system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and <span class="hlt">hydrothermal</span> explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the <span class="hlt">hydrothermal</span> system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the <span class="hlt">hydrothermal</span> system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of <span class="hlt">hydrothermal</span> explosions and their relation to glacial cycles, defining possible links between <span class="hlt">hydrothermal</span> activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive <span class="hlt">hydrothermal</span> activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004E%26PSL.222..819K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004E%26PSL.222..819K"><span id="translatedtitle">Tungsten enriched in submarine <span class="hlt">hydrothermal</span> fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kishida, Koichi; Sohrin, Yoshiki; Okamura, Kei; Ishibashi, Jun-ichiro</p> <p>2004-06-01</p> <p>Here we report the first data for W in <span class="hlt">hydrothermal</span> vent fluids in the deep oceans. Vented <span class="hlt">hydrothermal</span> fluids were collected from the Kairei Field, a mid ocean ridge <span class="hlt">hydrothermal</span> field at the Rodriguez Triple Junction, Central Indian Ridge, and from arc-backarc <span class="hlt">hydrothermal</span> systems at the Suiyo Seamount in the Izu-Bonin Arc, North Pacific Ocean and at the Hatoma and Yonaguni Knolls in the Okinawa Trough, East China Sea. While the dissolved W concentration in <span class="hlt">hydrothermal</span> fluids linearly increased with a decrease in the Mg concentration for each system, the W concentration in endmember fluids was very different. It was 0.21 nmol/kg at the Kairei Field, 15 nmol/kg at the Suiyo Seamount, and 123 nmol/kg at the Hatoma Knoll, which was 4 orders of magnitude above the ambient level in seawater. The W concentration was not a simple function of Cl, alkalinity, B, and NH 4. The <span class="hlt">hydrothermal</span> fields are efficiently enriched with W through reaction with fractionated calc-alkaline dacite and with terrigenous sediments. Although Mo is a chemical analogue of W in oxic seawater, the Mo concentration decreased in the <span class="hlt">hydrothermal</span> fluids to 2-7 nmol/kg probably due to precipitation of Mo sulfide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/879794','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/879794"><span id="translatedtitle">Hyperbaric <span class="hlt">Hydrothermal</span> Atomic Force Microscope</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.</p> <p>2003-07-01</p> <p>A hyperbaric <span class="hlt">hydrothermal</span> atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/874670','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/874670"><span id="translatedtitle">Hyperbaric <span class="hlt">hydrothermal</span> atomic force microscope</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.</p> <p>2002-01-01</p> <p>A hyperbaric <span class="hlt">hydrothermal</span> atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.B12B..02P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.B12B..02P&link_type=ABSTRACT"><span id="translatedtitle">Seawater bicarbonate removal during <span class="hlt">hydrothermal</span> circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Proskurowski, G. K.; Seewald, J.; Sylva, S. P.; Reeves, E.; Lilley, M. D.</p> <p>2013-12-01</p> <p>High temperature fluids sampled at <span class="hlt">hydrothermal</span> vents represent a complex alteration product of water-rock reactions on a multi-component mixture of source fluids. Sources to high-temperature <span class="hlt">hydrothermal</span> samples include the 'original' seawater present in the recharge limb of circulation, magmatically influenced fluids added at depth as well as any seawater entrained during sampling. High-temperature <span class="hlt">hydrothermal</span> fluids are typically enriched in magmatic volatiles, with CO2 the dominant species, characterized by concentrations of 10's-100's of mmol/kg (1, 2). Typically, the high concentration of CO2 relative to background seawater bicarbonate concentrations (~2.3 mmol/kg) obscures a full analysis of the fate of seawater bicarbonate during high-temperature <span class="hlt">hydrothermal</span> circulation. Here we present data from a suite of samples collected over the past 15 years from high-temperature <span class="hlt">hydrothermal</span> vents at 9N, Endeavour, Lau Basin, and the MAR that have endmember CO2 concentrations less than 10 mmol/kg. Using stable and radiocarbon isotope measurements these samples provide a unique opportunity to examine the balance between 'original' seawater bicarbonate and CO2 added from magmatic sources. Multiple lines of evidence from multiple <span class="hlt">hydrothermal</span> settings consistently points to the removal of ~80% of the 'original' 2.3 mmol/kg seawater bicarbonate. Assuming that this removal occurs in the low-temperature, 'recharge' limb of <span class="hlt">hydrothermal</span> circulation, this removal process is widely occurring and has important contributions to the global carbon cycle over geologic time. 1. Lilley MD, Butterfield DA, Lupton JE, & Olson EJ (2003) Magmatic events can produce rapid changes in <span class="hlt">hydrothermal</span> vent chemistry. Nature 422(6934):878-881. 2. Seewald J, Cruse A, & Saccocia P (2003) Aqueous volatiles in <span class="hlt">hydrothermal</span> fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity. Earth and Planetary Science Letters 216(4):575-590.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21232364','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21232364"><span id="translatedtitle">Biogeography of <span class="hlt">hydrothermal</span> vent communities along seafloor spreading centers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Dover, C L</p> <p>1990-08-01</p> <p>Compared to terrestrial and shallow-water habitats, deep-sea <span class="hlt">hydrothermal</span> vents are unique environments characterized by their local insularity, global distribution, individual ephemerality, collective geological longevity, geochemical homogeneity, and their physical and energetic isolation from the catastrophic events implicated in the extinction and speciation of terrestrial and shallow-water forms. Development of vent communities has thus occurred in novel biogeographical contexts that challenge our ability to understand evolutionary processes in the deep sea. Recent field work by French, Canadian, German, Japanese and American scientists has revealed intriguing patterns in the taxonomic composition and distribution of vent organisms at geographically disjunct study <span class="hlt">sites</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21232364','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21232364"><span id="translatedtitle">Biogeography of <span class="hlt">hydrothermal</span> vent communities along seafloor spreading centers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Dover, C L</p> <p>1990-08-01</p> <p>Compared to terrestrial and shallow-water habitats, deep-sea <span class="hlt">hydrothermal</span> vents are unique environments characterized by their local insularity, global distribution, individual ephemerality, collective geological longevity, geochemical homogeneity, and their physical and energetic isolation from the catastrophic events implicated in the extinction and speciation of terrestrial and shallow-water forms. Development of vent communities has thus occurred in novel biogeographical contexts that challenge our ability to understand evolutionary processes in the deep sea. Recent field work by French, Canadian, German, Japanese and American scientists has revealed intriguing patterns in the taxonomic composition and distribution of vent organisms at geographically disjunct study <span class="hlt">sites</span>. PMID:21232364</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5641454','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5641454"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> industrialization electric-power systems development. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1982-03-01</p> <p>The nature of <span class="hlt">hydrothermal</span> resources, their associated temperatures, geographic locations, and developable capacity are described. The parties involved in development, required activities and phases of development, regulatory and permitting requirements, environmental considerations, and time required to complete development activities ae examined in detail. These activities are put in proper perspective by detailing development costs. A profile of the geothermal industry is presented by detailing the participants and their operating characteristics. The current development status of geothermal energy in the US is detailed. The work on market penetration is summarized briefly. Detailed development information is presented for 56 high temperature <span class="hlt">sites</span>. (MHR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13B1747F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13B1747F"><span id="translatedtitle">In situ chemical sensing for <span class="hlt">hydrothermal</span> plume mapping and modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukuba, T.; Kusunoki, T.; Maeda, Y.; Shitashima, K.; Kyo, M.; Fujii, T.; Noguchi, T.; Sunamura, M.</p> <p>2012-12-01</p> <p>Detection, monitoring, and mapping of biogeochemical anomalies in seawater such as temperature, salinity, turbidity, oxidation-reduction potential, and pH are essential missions to explore undiscovered <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> and to understand distribution and behavior of <span class="hlt">hydrothermal</span> plumes. Utilization of reliable and useful in situ sensors has been widely accepted as a promised approach to realize a spatiotemporally resolved mapping of anomalies without water sampling operations. Due to remarkable progresses of sensor technologies and its relatives, a number of highly miniaturized and robust chemical sensors have been proposed and developed. We have been developed, evaluated, and operated a compact ISFET (Ion-Sensitive Field-Effect Transistor)-based chemical sensors for ocean environmental sensing purposes. An ISFET has advantages against conventional glass-based electrodes on its faster response, robustness, and potential on miniaturization, and thus variety of chemical sensors has been already on the market. In this study, ISFET-based standalone pH sensors with a solid-state Cl-ISE as a reference electrode were mounted on various platforms and operated to monitor the pH anomalies in deep-sea environment at the Kairei, Edmond, and surrounding <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in the southern Central Indian Ridge area during KH10-06 scientific cruise (Nov. 2010), supported by project TAIGA (Trans-crustal Advection and In situ biogeochemical processes of Global sub-seafloor Aquifer). Up to three pH sensors were mounted on a wire-lined CTD/RMS (Rosette Multiple Sampler), dredge sampler, a series of MTD plankton nets, and VMPS (Vertical Multiple-operating Plankton Sampler). A standalone temperature sensor was bundled and operated with the pH sensor when they were mounted on the dredge sampler, MTD plankton nets, and VMPS. An AUV equipped with the pH sensor was also operated for <span class="hlt">hydrothermal</span> activity survey operations. As a result of Tow-Yo intersect operations of the CTD</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/895893','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/895893"><span id="translatedtitle">What Defines a Separate <span class="hlt">Hydrothermal</span> System</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lawless, J.V.; Bogie, I.; Bignall, G.</p> <p>1995-01-01</p> <p>Separate <span class="hlt">hydrothermal</span> systems can be defined in a variety of ways. Criteria which have been applied include separation of heat source, upflow, economic resource and geophysical anomaly. Alternatively, connections have been defined by the effects of withdrawal of economically useful fluid and subsidence, effects of reinjection, changes in thermal features, or by a hydrological connection of groundwaters. It is proposed here that: ''A separate <span class="hlt">hydrothermal</span> system is one that is fed by a separate convective upflow of fluid, at a depth above the brittle-ductile transition for the host rocks, while acknowledging that separate <span class="hlt">hydrothermal</span> systems can be hydrologically interconnected at shallower levels''.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17793659','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17793659"><span id="translatedtitle">Catastrophic volcanic collapse: relation to <span class="hlt">hydrothermal</span> processes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>López, D L; Williams, S N</p> <p>1993-06-18</p> <p>Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of <span class="hlt">hydrothermal</span> discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between <span class="hlt">hydrothermal</span> fluids and the volcanic edifice. Rock dissolution and <span class="hlt">hydrothermal</span> mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PCM....40..733R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PCM....40..733R"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of pyrochlores and their characterization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Redkin, Alexander F.; Ionov, Andrey M.; Kotova, Nataliya P.</p> <p>2013-10-01</p> <p>Pyrochlores, microlites, and U-betafites of pyrochlore group minerals were obtained from mixing experiments of the corresponding oxides and fluorides by <span class="hlt">hydrothermal</span> synthesis at T = 800 °C and P = 200 MPa in the solution of 1.0 M NaF. The presence of U4+ in pyrochlore does not affect the cell parameter, which for the phases of pyrochlore-microlite series is 10.42 ± 0.01 Å. In a system with an excess of UO2, pyrochlores and microlites, containing uranium up to 0.2-0.3 atoms per formula unit (apfu), are formed. In the uranium-free system of betafites composition, perovskites and Ti-bearing pyrochlores are formed. U-pyrochlores of betafite series, containing 2Ti = Nb + Ta in moles, have cubic cell parameters of 10.26 ± 0.02 Å and U4+ isomorphic capacity of 0.4-0.5 apfu. In the pyrochlore structure, U4+ may substitute for Ca2+ and Na+ cations in the eightfold <span class="hlt">site</span>. In pyrochlores of pyrochlore-microlite series, Ca2+ is replaced by U4+, while in pyrochlores of betafite series, U4+ replaces Na+. Phases with pyrochlore structure, containing U5+ and U6+ in the sixfold <span class="hlt">site</span>, usually occupied by Nb5+, Ta5+, and Ti4+, are formed under oxidizing conditions (Cu-Cu2O buffer). They are characterized by low content of Nb5+, Ta5+ (<0.1 apfu), and anomalous behavior of the crystal lattice (compression, instead of expansion). Under natural conditions, the formation of pyrochlores containing a significant amount of U5+ and U6+ is unlikely.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930004270','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930004270"><span id="translatedtitle">Chemical environments of submarine <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, Everett L.</p> <p>1992-01-01</p> <p>Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine <span class="hlt">hydrothermal</span> systems were involved in the origin of life has caused many investigators to focus on the eye-catching <span class="hlt">hydrothermal</span> vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature <span class="hlt">hydrothermal</span> vents to the near exclusion of the enormous underlying <span class="hlt">hydrothermal</span> systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine <span class="hlt">hydrothermal</span> systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine <span class="hlt">hydrothermal</span> vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of <span class="hlt">hydrothermal</span> processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine <span class="hlt">hydrothermal</span> systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine <span class="hlt">hydrothermal</span> systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V43B2880G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V43B2880G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Monitoring in a Quiescent Volcanic Arc: Cascade Range, Northwestern United States</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gelwick, K.; Randolph-Flagg, N. G.; Crankshaw, I. M.; McCulloch, C. L.; Lundstrom, E. A.; Murveit, A. M.; Bergfeld, D.; Spicer, K.; Tucker, D.; Schmidt, M. E.; Mariner, R. H.; Evans, W.; Ingebritsen, S.</p> <p>2013-12-01</p> <p>Ongoing (1996-present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of <span class="hlt">hydrothermal</span> anomalies, including elevated temperatures, elevated major-ion concentrations, and 3He/4He ratios as large as 8.6 RA in slightly thermal springs. These observations prompted the U.S. Geological Survey to begin a systematic <span class="hlt">hydrothermal</span>-monitoring effort encompassing 25 <span class="hlt">sites</span> and 10 of the highest-risk volcanoes in the Cascade Range volcanic arc, from Mount Baker near the Canadian border to Mount Lassen in northern California. A concerted effort was made to develop hourly records of temperature and (or) <span class="hlt">hydrothermal</span> solute flux spanning multiple years, suitable for comparison with other continuous geophysical monitoring data. Monitored <span class="hlt">sites</span> included summit-fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high 3He/4He ratios and (or) large fluxes of magmatic CO2 or heat. As of 2009-2012 measured summit-fumarole temperatures in the Cascade Range were generally near or below the local pure-water boiling point; the maximum observed superheat was <+2.5°C at Mount Baker. Temporal variability in ground-temperature records from the summit-fumarole <span class="hlt">sites</span> is temperature-dependent, with the hottest <span class="hlt">sites</span> tending to show less variability. Seasonal variability in the flux of <span class="hlt">hydrothermally</span> sourced major anions from the springs varied from essentially undetectable to a factor of 5-10. This range of observed behavior owes mainly to the local climate regime, with strongly snowmelt-influenced springs and streams exhibiting more variability. As of the end of the 2012 field season, there had been 87 occurrences of local seismic energy densities ~>0.001 J/m3 during periods of hourly record. <span class="hlt">Hydrothermal</span> responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multi-decadal trends indicates that whereas the <span class="hlt">hydrothermal</span> system at Mount St. Helens is still fast-evolving in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20455940','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20455940"><span id="translatedtitle">Marine culturable yeasts in deep-sea <span class="hlt">hydrothermal</span> vents: species richness and association with fauna.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burgaud, Gaëtan; Arzur, Danielle; Durand, Lucile; Cambon-Bonavita, Marie-Anne; Barbier, Georges</p> <p>2010-07-01</p> <p>Investigations of the diversity of culturable yeasts at deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> have suggested possible interactions with endemic fauna. Samples were collected during various oceanographic cruises at the Mid-Atlantic Ridge, South Pacific Basins and East Pacific Rise. Cultures of 32 isolates, mostly associated with animals, were collected. Phylogenetic analyses of 26S rRNA gene sequences revealed that the yeasts belonged to Ascomycota and Basidiomycota phyla, with the identification of several genera: Rhodotorula, Rhodosporidium, Candida, Debaryomyces and Cryptococcus. Those genera are usually isolated from deep-sea environments. To our knowledge, this is the first report of yeasts associated with deep-sea <span class="hlt">hydrothermal</span> animals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/840686','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/840686"><span id="translatedtitle">Products of an Artificially Induced <span class="hlt">Hydrothermal</span> System at Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>S. Levy</p> <p>2000-08-07</p> <p>Studies of mineral deposition in the recent geologic past at Yucca Mountain, Nevada, address competing hypotheses of <span class="hlt">hydrothermal</span> alteration and deposition from percolating groundwater. The secondary minerals being studied are calcite-opal deposits in fractures and lithophysal cavities of ash-flow tuffs exposed in the Exploratory Studies Facility (ESF), a 7.7-km tunnel excavated by the Yucca Mountain <span class="hlt">Site</span> Characterization Project within Yucca Mountain. An underground field test in the ESF provided information about the minerals deposited by a short-lived artificial <span class="hlt">hydrothermal</span> system and an opportunity for comparison of test products with the natural secondary minerals. The heating phase lasted nine months, followed by a nine-month cooling period. Natural pore fluids were the only source of water during the thermal test. Condensation and reflux of water driven away from the heater produced fluid flow in certain fractures and intersecting boreholes. The mineralogic products of the thermal test are calcite-gypsum aggregates of less than 4-micrometer crystals and amorphous silica as glassy scale less than 0.2 mm thick and as mounds of tubules with diameters less than 0.7 micrometers. The minute crystal sizes of calcite and gypsum from the field test are very different from the predominantly coarser calcite crystals (up to cm scale) in natural secondary-mineral deposits at the <span class="hlt">site</span>. The complex micrometer-scale textures of the amorphous silica differ from the simple forms of opal spherules and coatings in the natural deposits, even though some natural spherules are as small as 1 micrometer. These differences suggest that the natural minerals, especially if they were of <span class="hlt">hydrothermal</span> origin, may have developed coarser or simpler forms during subsequent episodes of dissolution and redeposition. The presence of gypsum among the test products and its absence from the natural secondary-mineral assemblage may indicate a higher degree of evaporation during the test than</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V31B4737L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V31B4737L"><span id="translatedtitle">Modeling Crustal-Scale <span class="hlt">Hydrothermal</span> Flows through a Seamount Network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lauer, R. M.; Fisher, A. T.; Winslow, D. M.</p> <p>2014-12-01</p> <p>The current study represents the first efforts to model 3D <span class="hlt">hydrothermal</span> circulation in fast-spreading oceanic crust, using a network of outcrops patterned after a region of the Cocos plate offshore Costa Rica, where heat extraction is exceptionally high, resulting in heat flow values ~30% of those predicted by conductive lithospheric cooling models. Previous studies of this region attribute the heat deficit to vigorous <span class="hlt">hydrothermal</span> circulation through basaltic basement outcrops that provide a hydraulic connection between the igneous oceanic crust and the seafloor, resulting in efficient mining of heat by large-scale lateral fluid flow. Seafloor bathymetry indicates that outcrops in this region are spaced 20-50-km apart, although there are likely additional unmapped structures that facilitate recharge and discharge of <span class="hlt">hydrothermal</span> fluids. The modeled outcrop network consists of 20-km and 40-km square grids, with outcrops located at the corners. We vary the number, size, permeability, and orientation of the outcrops to consider what combination of these parameters achieve the observed pattern and/or quantity of heat loss. Additionally, we consider the effect of aquifer permeability and thickness on the modeled heat flow distribution. Model results suggest that extremely high aquifer permeability is required to match the observed heat loss and low heat flow, together with a heterogeneous outcrop permeability distribution. In particular, we find that an aquifer permeability of 10-9 m2 is required to achieve the measured heat flow distribution in this region, which estimates a mean value of 29 ±13 mW/m2 in areas of flat lying basement, overlain by 400-500-m of sediment. In addition to high aquifer permeability, heterogeneous outcrop permeability is required to initiate the hydraulic connection between outcrops, with higher permeability outcrops acting as recharge <span class="hlt">sites</span>, and lower permeability outcrops as discharge <span class="hlt">sites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5158533','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5158533"><span id="translatedtitle">Rare earth element systematics in <span class="hlt">hydrothermal</span> fluids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Michard, A. )</p> <p>1989-03-01</p> <p>Rare earth element concentrations have been measured in <span class="hlt">hydrothermal</span> solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that <span class="hlt">hydrothermal</span> activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (> 230{degree}C) percolating through different rock types may show similar REE patterns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5347450','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5347450"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> industrialization: direct heat development. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1982-05-01</p> <p>A description of <span class="hlt">hydrothermal</span> resources suitable for direct applications, their associated temperatures, geographic distribution and developable capacity are given. An overview of the <span class="hlt">hydrothermal</span> direct-heat development infrastructure is presented. Development activity is highlighted by examining known and planned geothermal direct-use applications. Underlying assumptions and results for three studies conducted to determine direct-use market penetration of geothermal energy are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MinDe..48..233C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MinDe..48..233C"><span id="translatedtitle">Migration of <span class="hlt">hydrothermal</span> systems in an evolving collisional orogen, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Craw, D.; Upton, P.; Horton, T.; Williams, J.</p> <p>2013-02-01</p> <p>The Pacific-Australian tectonic plate boundary through the South Island of New Zealand consists of the transpressional Southern Alps mountain belt and the transcurrent Marlborough Fault System, both of which have active tectonically driven <span class="hlt">hydrothermal</span> systems, with topographically driven meteoric incursion and warm springs. The Southern Alps <span class="hlt">hydrothermal</span> system is relatively diffuse, with little or no fault control, and is channelled through scattered extensional <span class="hlt">sites</span> beneath the mountains, where gold mineralisation is occurring locally. The <span class="hlt">hydrothermal</span> activity along the Marlborough Fault System is controlled by the principal faults in well-defined valleys separated by narrow high ridges. Lateral evolution of Marlborough fault strands southwestwards into the Southern Alps has caused diversion of diffuse Southern Alps <span class="hlt">hydrothermal</span> activity into the structural superimposition zone, where fluid flow is increasingly being controlled by faults. This <span class="hlt">hydrothermal</span> diversion was accompanied by major topographic reorientation and river drainage reversal in the late Quaternary. Vein swarms now exposed in the remnants of the Southern Alps north of the superimposition zone formed at shallow levels, with some evidence for fluid boiling, from a mixture of meteoric and deep-sourced fluid. These veins, some of which contain gold, are part of an abandoned <1 million-year-old <span class="hlt">hydrothermal</span> zone beneath the fossil topographic divide of the Southern Alps that has now been dismembered by lateral incursion of the Marlborough fault strands. Observations on this active plate boundary provide some insights into processes that controlled orogenic gold mineralisation in ancient belts, particularly with respect to relationships between <span class="hlt">hydrothermal</span> fluid flow, structure and topography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS51B1867F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS51B1867F&link_type=ABSTRACT"><span id="translatedtitle">Characterization of Magma-Driven <span class="hlt">Hydrothermal</span> Systems at Oceanic Spreading Centers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farough, A.; Lowell, R. P.; Corrigan, R.</p> <p>2012-12-01</p> <p>Fluid circulation in high-temperature <span class="hlt">hydrothermal</span> systems involves complex water-rock chemical reactions and phase separation. Numerical modeling of reactive transport in multi-component, multiphase systems is required to obtain a full understanding of the characteristics and evolution of <span class="hlt">hydrothermal</span> vent systems. We use a single-pass parameterized model of high-temperature <span class="hlt">hydrothermal</span> circulation at oceanic spreading centers constrained by observational parameters such as vent temperature, heat output, and vent field area, together with surface area and depth of the sub-axial magma chamber, to deduce fundamental <span class="hlt">hydrothermal</span> parameters such as mass flow rate, bulk permeability, conductive boundary layer thickness at the base of the system, magma replenishment rate, and residence time in the discharge zone. All of these key subsurface characteristics are known for fewer than 10 <span class="hlt">sites</span> out of 300 known <span class="hlt">hydrothermal</span> systems. The principal limitations of this approach stem from the uncertainty in heat output and vent field area. For systems where data are available on partitioning of heat and chemical output between focused and diffuse flow, we determined the fraction of high-temperature vent fluid incorporated into diffuse flow using a two-limb single pass model. For EPR 9°50` N and ASHES, the diffuse flow temperatures calculated assuming conservative mixing are nearly equal to the observed temperatures indicating that approximately 80%-90% of the <span class="hlt">hydrothermal</span> heat output occurs as high-temperature flow derived from magmatic heat even though most of the heat output appears as low-temperature diffuse discharge. For the Main Endeavour Field and Lucky Strike, diffuse flow fluids show significant conductive cooling and heating respectively. Finally, we calculate the transport of various geochemical constituents in focused and diffuse flow at the vent field scale and compare the results with estimates of geochemical transports from the Rainbow <span class="hlt">hydrothermal</span> field where</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70117573','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70117573"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ingebritsen, S.E.; Randolph-Flagg, N. G.; Gelwick, K.D.; Lundstrom, E.A.; Crankshaw, I.M.; Murveit, A.M.; Schmidt, M.E.; Bergfeld, D.; Spicer, K.R.; Tucker, D.S.; Mariner, R.H.; Evans, William C.</p> <p>2014-01-01</p> <p>Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of <span class="hlt">hydrothermal</span> anomalies, including elevated temperatures, elevated major ion concentrations, and 3He/4He ratios as large as 8.6 RA in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic <span class="hlt">hydrothermal</span>-monitoring effort encompassing 25 <span class="hlt">sites</span> and 10 of the highest-risk volcanoes in the Cascade volcanic arc, from Mount Baker near the Canadian border to Lassen Peak in northern California. A concerted effort was made to develop hourly, multiyear records of temperature and/or <span class="hlt">hydrothermal</span> solute flux, suitable for retrospective comparison with other continuous geophysical monitoring data. Targets included summit fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high 3He/4He ratios and/or anomalous fluxes of magmatic CO2 or heat. As of 2009–2012, summit fumarole temperatures in the Cascade Range were generally near or below the local pure water boiling point; the maximum observed superheat was 3 during periods of hourly record. <span class="hlt">Hydrothermal</span> responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multidecadal trends indicates that whereas the <span class="hlt">hydrothermal</span> system at Mount St. Helens is still fast-evolving in response to the 1980–present eruptive cycle, there is no clear evidence of ongoing long-term trends in <span class="hlt">hydrothermal</span> activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range <span class="hlt">hydrothermal</span>-monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.V21D0759K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V21D0759K"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> fountains imaged by high resolution side-scan sonar equipped on a cruising AUV, URASHIMA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumagai, H.; Tsukioka, S.; Yamamoto, H.; Shitashima, K.; Yamamoto, F.; Sawa, T.; Hyakudome, T.; Kasaya, T.; Kinoshita, M.</p> <p>2007-12-01</p> <p>Mapping of an area and intensities of activity at a particular <span class="hlt">hydrothermal</span> field has required huge effort so far, typically several tens of dives of manned submersibles and/or ROVs to obtain detailed locality map with needed resolutions. Thus, appropriate remote sensing techniques have been desired since the discovery of seafloor <span class="hlt">hydrothermal</span> field. A series of successful trials has been performed by ABE of WHOI equipped with a Eh-sensor (Yoerger et al., Oceanography, 2007). A 100kHz side-scan sonar (SSS) equipped on a cruising AUV, URASHIMA, caught detailed structural image of <span class="hlt">hydrothermal</span> fountains rooting active chimneys during YK07-07 Cruise off Okinawa Isl. (May 6-18, 2007). The URASHIMA AUV is a 10-m-length cylindrical-shaped one that originally optimized to long distance cruise. In the expedition, she cruised near the sea floor with 50-100 m altitude, at the area of 1000-1500 m in WD. She has currently basic oceanographic/CTD sensors, a 400kHz echo-sounder and sonars of 100400 kHz side-scan sonar and up to 6 kHz sub-bottom profiler. In this operation, pH and ORP sensors (CRIEPI) were also attached in front of AUV. On the pre-processing image of SSS, numbers of filament-shape echoes were recorded within water column zone. The reason why they should be the echo from <span class="hlt">hydrothermal</span> plumes are as folows; 1) the echoes in the water column were limitedly recorded above the active <span class="hlt">hydrothermal</span> field; 2) CTD and pH sensors show temperature and pH anomaly corresponding to the record of echoes; 3) some of the root of the filament-shape echoes correspond to the <span class="hlt">hydrothermal</span> mound recognized in the detailed bathymetry obtained with SeaBat7125 MNBES. This-like technique should revolute the mapping work prior to the sampling at the particular <span class="hlt">hydrothermal</span> <span class="hlt">site</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816742H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816742H"><span id="translatedtitle">The influence of isotropic and anisotropic crustal permeability on <span class="hlt">hydrothermal</span> flow at fast spreading ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasenclever, Jörg; Rüpke, Lars; Theissen-Krah, Sonja; Morgan, Jason</p> <p>2016-04-01</p> <p>We use 3-D numerical models of <span class="hlt">hydrothermal</span> fluid flow to assess the magnitude and spatial distribution of <span class="hlt">hydrothermal</span> mass and energy fluxes within the upper and lower oceanic crust. A better understanding of the <span class="hlt">hydrothermal</span> flow pattern (e.g. predominantly on-axis above the axial melt lens vs. predominantly off-axis and ridge-perpendicular over the entire crustal thickness) is essential for quantifying the volume of oceanic crust exposed to high-temperature fluid flow and the associated leaching and redistribution of economically interesting metals. The initial setup of all 3-D models is based on our previous 2-D studies (Theissen-Krah et al., 2011), in which we have coupled numerical models for crustal accretion and <span class="hlt">hydrothermal</span> fluid flow. One result of these 2-D calculations is a crustal permeability field that leads to a thermal structure in the crust that matches seismic tomography data at the East Pacific Rise. Our reference 3-D model for <span class="hlt">hydrothermal</span> flow at fast-spreading ridges predicts the existence of a hybrid <span class="hlt">hydrothermal</span> system (Hasenclever et al., 2014) with two interacting flow components that are controlled by different physical mechanisms. Shallow on-axis flow structures develop owing to the thermodynamic properties of water, whereas deeper off-axis flow is strongly shaped by crustal permeability, particularly the brittle-ductile transition. About ˜60% of the discharging fluid mass is replenished on-axis by warm (up to 300oC) recharge flow surrounding the hot thermal plumes. The remaining ˜40%, however, occurs as colder and broader recharge up to several kilometres away from the ridge axis that feeds hot (500-700oC) deep off-axis flow in the lower crust towards the ridge. Both flow components merge above the melt lens to feed ridge-centred vent <span class="hlt">sites</span>. In a suite of 3-D model calculations we vary the isotropic crustal permeability to quantify its influence on on-axis vs. off-axis <span class="hlt">hydrothermal</span> fluxes as well as on along-axis <span class="hlt">hydrothermal</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009DSRII..56.1577E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009DSRII..56.1577E"><span id="translatedtitle">Evidence for a chemoautotrophically based food web at inactive <span class="hlt">hydrothermal</span> vents (Manus Basin)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Erickson, K. L.; Macko, S. A.; Van Dover, C. L.</p> <p>2009-09-01</p> <p><span class="hlt">Hydrothermal</span> vents are ephemeral systems. When venting shuts down, sulfide-dependent taxa die off, and non-vent taxa can colonize the hard substrata. In Manus Basin (Papua New Guinea), where <span class="hlt">hydrothermally</span> active and inactive <span class="hlt">sites</span> are interspersed, hydroids, cladorhizid sponges, barnacles, bamboo corals, and other invertebrate types may occupy inactive <span class="hlt">sites</span>. Carbon and nitrogen isotopic compositions of animals occupying inactive <span class="hlt">sites</span> are consistent with nutritional dependence on either chemoautotrophically or photosynthetically produced organic material, but sulfur isotopic compositions of these animals point to a chemoautotrophic source of sulfur from dissolved sulfide in vent fluids rather than sulfur derived from seawater sulfate through photosynthesis. Given that suspension-feeding and micro-carnivorous invertebrates are the biomass dominants at inactive <span class="hlt">sites</span>, the primary source of chemoautotrophic nutrition is likely suspended particulates and organisms delivered from nearby active vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950037876&hterms=Pacific+ridge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DPacific%2Bridge','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950037876&hterms=Pacific+ridge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DPacific%2Bridge"><span id="translatedtitle">Constraints on <span class="hlt">hydrothermal</span> heat flux through the oceanic lithosphere from global heat flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stein, Carol A.; Stein, Seth</p> <p>1994-01-01</p> <p>A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by <span class="hlt">hydrothermal</span> circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of <span class="hlt">hydrothermal</span> flow, and the variation in the discrepancy with lithospheric age is the primary constraint on how the <span class="hlt">hydrothermal</span> flux is divided between near-ridge and off-ridge environments. The resulting estimates are important for investigation of both the thermal structure of the lithosphere and the chemistry of the oceans. We reevaluate the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDHI (Global Depth and Heat Flow) model that better predicts the heat flow. We estimate that of the predicted global oceanic heat flux of 32 x 10(exp 12) W, 34% (11 x 10(exp 12) W) occurs by <span class="hlt">hydrothermal</span> flow. Approximately 30% of the <span class="hlt">hydrothermal</span> heat flux occurs in crust younger than 1 Ma, so the majority of this flux is off-ridge. These <span class="hlt">hydrothermal</span> heat flux estimates are upper bounds, because heat flow measurements require sediment at the <span class="hlt">site</span> and so are made preferentially at topographic lows, where heat flow may be depressed. Because the water temperature for the near-ridge flow exceeds that for the off-ridge flow, the near-ridge water flow will be even a smaller fraction of the total water flow. As a result, in estimating fluxes from geochemical data, use of the high water temperatures appropriate for the ridge axis may significantly overestimate the heat flux for an assumed water flux or underestimate the water flux for an assumed heat flux. Our data also permit improved estimates of the 'sealing' age, defined as the age where the observed heat flow approximately equals that predicted, suggesting</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995CSR....15..913D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995CSR....15..913D"><span id="translatedtitle">Gas venting rates from submarine <span class="hlt">hydrothermal</span> areas around the island of Milos, Hellenic Volcanic Arc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dando, P. R.; Hughes, J. A.; Leahy, Y.; Niven, S. J.; Taylor, L. J.; Smith, C.</p> <p>1995-07-01</p> <p>Gas seeps were located, by echo sounding, SCUBA divers and ROV observations, at <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> around the island of Milos, in the Hellenic Volcanic Arc. Samples were collected by SCUBA divers and by a ROV from water depths between 3 and 110 m. Fifty-six flow rates from 39 individual seeps were measured and these ranged from 0.2 to 18.51 h -1 at the depth of collection. The major component, 54.9-91.9% of the gas, was carbon dioxide. Hydrogen (≤3%), methane (≤9.7%) and hydrogen sulphide (≤8.1%) were also measured. <span class="hlt">Hydrothermal</span> free gas fluxes from the submarine <span class="hlt">hydrothermal</span> areas around Milos were estimated to be greater than 10 10 moles y -1. It was concluded that submarine gas seeps along volcanic island arcs may be an important carbon dioxide source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20975681','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20975681"><span id="translatedtitle">Deep-sea <span class="hlt">hydrothermal</span> vent animals seek cool fluids in a highly variable thermal environment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bates, Amanda E; Lee, Raymond W; Tunnicliffe, Verena; Lamare, Miles D</p> <p>2010-05-04</p> <p>The thermal characteristics of an organism's environment affect a multitude of parameters, from biochemical to evolutionary processes. <span class="hlt">Hydrothermal</span> vents on mid-ocean ridges are created when warm <span class="hlt">hydrothermal</span> fluids are ejected from the seafloor and mixed with cold bottom seawater; many animals thrive along these steep temperature and chemical gradients. Two-dimensional temperature maps at vent <span class="hlt">sites</span> have demonstrated order of magnitude thermal changes over centimetre distances and at time intervals from minutes to hours. To investigate whether animals adapt to this extreme level of environmental variability, we examined differences in the thermal behaviour of mobile invertebrates from aquatic habitats that vary in thermal regime. Vent animals were highly responsive to heat and preferred much cooler fluids than their upper thermal limits, whereas invertebrates from other aquatic environments risked exposure to warmer temperatures. Avoidance of temperatures well within their tolerated range may allow vent animals to maintain a safety margin against rapid temperature fluctuations and concomitant toxicity of <span class="hlt">hydrothermal</span> fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23647923','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23647923"><span id="translatedtitle">Linking geology, fluid chemistry, and microbial activity of basalt- and ultramafic-hosted deep-sea <span class="hlt">hydrothermal</span> vent environments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perner, M; Hansen, M; Seifert, R; Strauss, H; Koschinsky, A; Petersen, S</p> <p>2013-07-01</p> <p><span class="hlt">Hydrothermal</span> fluids passing through basaltic rocks along mid-ocean ridges are known to be enriched in sulfide, while those circulating through ultramafic mantle rocks are typically elevated in hydrogen. Therefore, it has been estimated that the maximum energy in basalt-hosted systems is available through sulfide oxidation and in ultramafic-hosted systems through hydrogen oxidation. Furthermore, thermodynamic models suggest that the greatest biomass potential arises from sulfide oxidation in basalt-hosted and from hydrogen oxidation in ultramafic-hosted systems. We tested these predictions by measuring biological sulfide and hydrogen removal and subsequent autotrophic CO2 fixation in chemically distinct <span class="hlt">hydrothermal</span> fluids from basalt-hosted and ultramafic-hosted vents. We found a large potential of microbial hydrogen oxidation in naturally hydrogen-rich (ultramafic-hosted) but also in naturally hydrogen-poor (basalt-hosted) <span class="hlt">hydrothermal</span> fluids. Moreover, hydrogen oxidation-based primary production proved to be highly attractive under our incubation conditions regardless whether <span class="hlt">hydrothermal</span> fluids from ultramafic-hosted or basalt-hosted <span class="hlt">sites</span> were used. <span class="hlt">Site</span>-specific hydrogen and sulfide availability alone did not appear to determine whether hydrogen or sulfide oxidation provides the energy for primary production by the free-living microbes in the tested <span class="hlt">hydrothermal</span> fluids. This suggests that more complex features (e.g., a combination of oxygen, temperature, biological interactions) may play a role for determining which energy source is preferably used in chemically distinct <span class="hlt">hydrothermal</span> vent biotopes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/684582','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/684582"><span id="translatedtitle">Characterization and catalytic properties of <span class="hlt">hydrothermally</span> dealuminated MCM-22</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Meriaudeau, P.; Tuan, V.A.; Nghiem, V.T.; Ha, V.T.</p> <p>1999-07-25</p> <p>Zeolite MCM-22 was recently patented as a useful catalyst for alkylation and isomerization reactions and for conversion of methanol or olefins to hydrocarbons. MCM-22 has been synthesized and dealuminated by <span class="hlt">hydrothermal</span> treatments. The resulting solids were characterized by different techniques in order to know how the acid properties of the dealuminated solids were modified. It appears that the number of acid <span class="hlt">sites</span> was decreased by <span class="hlt">hydrothermal</span> treatments but the acid strength was not modified. Nondealuminated and dealuminated solids were used in the n-octane hydroconversion. Results suggested that for both types of solids the hydroisomerization is mainly occurring in the 10-membered ring (MR) channels whereas the hydrocracking is mainly coming from acid <span class="hlt">sites</span> located in 12-membered ring channels. According to the observed distribution of monobranched isomers, MCM-22 shows some ``shape-selective`` character typical of the pentasil family, whereas, according to the absolute yield of isopentane in the hydrocracked products at low hydrocracking conversions, MCM-22 behaves more like a 12 MR zeolite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..314..156S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..314..156S"><span id="translatedtitle">Subaerial and sublacustrine <span class="hlt">hydrothermal</span> activity at Lake Rotomahana</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stucker, Valerie K.; de Ronde, Cornel E. J.; Scott, Bradley J.; Wilson, Nathaniel J.; Walker, Sharon L.; Lupton, John E.</p> <p>2016-03-01</p> <p>Lake Rotomahana is a crater lake in the Okataina Volcanic Centre (New Zealand) that was significantly modified by the 1886 Tarawera Rift eruption. The lake is host to numerous sublacustrine <span class="hlt">hydrothermal</span> vents. Water column studies were conducted in 2011 and 2014 along with sampling of lake shore hot springs and crater lakes in Waimangu Valley to complement magnetic, seismic, bathymetric and heat flux surveys. Helium concentrations below 50 m depth are higher in 2014 compared to 2011 and represent some of the highest concentrations measured, at 6 × 10- 7 ccSTP/g, with an end-member 3He/4He value of 7.1 RA. The high concentrations of helium, when coupled with pH anomalies due to high dissolved CO2 content, suggest the dominant chemical input to the lake is derived from magmatic degassing of an underlying magma. The lake shore hot spring waters show differences in source temperatures using a Na-K geothermometer, with inferred reservoir temperatures ranging between 197 and 232 °C. Water δ18O and δD values show isotopic enrichment due to evaporation of a steam heated pool with samples from nearby Waimangu Valley having the greatest enrichment. Results from this study confirm both pre-1886 eruption <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> and newly created post-eruption <span class="hlt">sites</span> are both still active.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2010P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2010P"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> activity in Tertiary Icelandic crust: Implication for cooling processes along slow-spreading mid-ocean ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pałgan, D.; Devey, C. W.; Yeo, I. A.</p> <p>2015-12-01</p> <p>Known <span class="hlt">hydrothermal</span> activity along the Mid-Atlantic Ridge is mostly high-temperature venting, controlled by volcano-tectonic processes confined to ridge axes and neotectonic zones ~15km wide on each side of the axis (e.g. TAG or Snake Pit). However, extensive exploration and discoveries of new <span class="hlt">hydrothermal</span> fields in off-axis regions (e.g. Lost City, MAR) show that <span class="hlt">hydrothermalism</span> may, in some areas, be dominated by off-axis venting. Little is known about nature of such systems, including whether low-temperature "diffuse" venting dominates rather than high-temperature black-smokers. This is particularly interesting since such systems may transport up to 90% of the <span class="hlt">hydrothermal</span> heat to the oceans. In this study we use Icelandic hot springs as onshore analogues for off-shore <span class="hlt">hydrothermal</span> activity along the MAR to better understand volcano-tectonic controls on their occurrence, along with processes supporting fluid circulation. Iceland is a unique laboratory to study how new oceanic crust cools and suggests that old crust may not be as inactive as previously thought. Our results show that Tertiary (>3.3 Myr) crust of Iceland (Westfjords) has widespread low-temperature <span class="hlt">hydrothermal</span> activity. Lack of tectonism (indicated by lack of seismicity), along with field research suggest that faults in Westfjords are no longer active and that once sealed, can no longer support <span class="hlt">hydrothermal</span> circulation, i.e. none of the hot springs in the area occur along faults. Instead, dyke margins provide open and permeable fluid migration pathways. Furthermore, we suggest that the Reykjanes Ridge (south of Iceland) may be similar to Westfjords with <span class="hlt">hydrothermalism</span> dominated by off-axis venting. Using bathymetric data we infer dyke positions and suggest potential <span class="hlt">sites</span> for future exploration located away from neotectonic zone. We also emphasise the importance of biological observations in seeking for low-temperature <span class="hlt">hydrothermal</span> activity, since chemical or optical methods are not sufficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997E%26PSL.153..239F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997E%26PSL.153..239F"><span id="translatedtitle">Tide-related variability of TAG <span class="hlt">hydrothermal</span> activity observed by deep-sea monitoring system and OBSH</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujioka, Kantaro; Kobayashi, Kazuo; Kato, Kazuhiro; Aoki, Misumi; Mitsuzawa, Kyohiko; Kinoshita, Masataka; Nishizawa, Azusa</p> <p>1997-12-01</p> <p><span class="hlt">Hydrothermal</span> activities were monitored by an ocean bottom seismometer with hydrophone (OBSH) and a composite measuring system (Manatee) including CTD, current meter, transmission meter and cameras at a small depression on the TAG <span class="hlt">hydrothermal</span> mound in the Mid-Atlantic Ridge. Low-frequency pressure pulses detected by the hydrophone with semi-diurnal periodicity seem to correspond to cycles of <span class="hlt">hydrothermal</span> upflow from a small and short-lived smoker vent close to the observing <span class="hlt">site</span>. The peaks of pressure pulses are synchronous with the maximum gradient of areal strain decrease due to tidal load release. Microearthquakes with very near epicenters occur sporadically and do not appear to be directly correlatable to <span class="hlt">hydrothermal</span> venting. Temporal variations in bottom water temperature also have semi-diurnal periodicity but are more complicated than the pressure events. Temperatures may be affected both by upwelling of hot water and by lateral flow of the bottom current changing its directions with ocean tide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12522264','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12522264"><span id="translatedtitle">Autochthonous eukaryotic diversity in <span class="hlt">hydrothermal</span> sediment and experimental microcolonizers at the Mid-Atlantic Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>López-García, Purificación; Philippe, Hervé; Gail, Françoise; Moreira, David</p> <p>2003-01-21</p> <p>The diversity and mode of life of microbial eukaryotes in <span class="hlt">hydrothermal</span> systems is very poorly known. We carried out a molecular survey based on 18S ribosomal RNA genes of eukaryotes present in different <span class="hlt">hydrothermal</span> niches at the Mid-Atlantic Ridge. These included metal-rich and rare-earth-element-rich <span class="hlt">hydrothermal</span> sediments of the Rainbow <span class="hlt">site</span>, fluid-seawater mixing regions, and colonization devices (microcolonizers) containing organic, iron-rich, and porous mineral substrates that were exposed for 15 days to a fluid source. We identified considerable phylogenetic diversity, both at kingdom level and within kinetoplastids and alveolates. None of our sequences affiliates to photosynthesizing lineages, suggesting that we are targeting only autochthonous deep-sea communities. Although sediment harbored most phylogenetic diversity, microcolonizers predominantly contained bodonids and ciliates, indicating that these protists pioneer the colonization process. Given the large variety of divergent lineages detected within the alveolates in deep-sea plankton, <span class="hlt">hydrothermal</span> sediments, and vents, alveolates seem to dominate the deep ocean in terms of diversity. Compared with data from the Pacific Guaymas basin, some protist lineages seem ubiquitous in <span class="hlt">hydrothermal</span> areas, whereas others, notably kinetoplastid lineages, very abundant and diverse in our samples, so far have been detected only in Atlantic systems. Unexpectedly, although alvinellid polychaetes are considered endemic of Pacific vents, we detected alvinellid-related sequences at the fluid-seawater interface and in microcolonizers. This finding can boost further studies on deep-sea vent animal biology and biogeography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12529639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12529639"><span id="translatedtitle">Discovery of abundant <span class="hlt">hydrothermal</span> venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Edmonds, H N; Michael, P J; Baker, E T; Connelly, D P; Snow, J E; Langmuir, C H; Dick, H J B; Mühe, R; German, C R; Graham, D W</p> <p>2003-01-16</p> <p>Submarine <span class="hlt">hydrothermal</span> venting along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such vents has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of vent-endemic organisms. Previous studies have predicted that the incidence of <span class="hlt">hydrothermal</span> venting would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates <2 cm x yr(-1)-which make up 25 per cent of the global ridge length), and that such vent systems would be hosted in ultramafic in addition to volcanic rocks. Here we present evidence for active <span class="hlt">hydrothermal</span> venting on the Gakkel ridge, which is the slowest spreading (0.6-1.3 cm x yr(-1)) and least explored mid-ocean ridge. On the basis of water column profiles of light scattering, temperature and manganese concentration along 1,100 km of the rift valley, we identify <span class="hlt">hydrothermal</span> plumes dispersing from at least nine to twelve discrete vent <span class="hlt">sites</span>. Our discovery of such abundant venting, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control <span class="hlt">hydrothermal</span> circulation on ultraslow-spreading ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/45824','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/45824"><span id="translatedtitle">Structure of two <span class="hlt">hydrothermal</span> megaplumes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>D`asaro, E.; Walker, S.; Baker, E. |</p> <p>1994-10-01</p> <p>The dynamic signatures of two megaplumes above the Juan de Fuca Ridge are analyzed. The chemical properties of these two lenslike masses of water were described by Baker at al. (1989) and clearly indicate that they were generated by massive and rapid ventings of hot <span class="hlt">hydrothermal</span> fluid from the ridge. Both are nearly circular with radii of about 6.5 km. The isopycnals bow upward around these cores of anomalous water, leading to an anticyclonic circulation. A cyclogeostrophic balance gives maximum currents at the edge of the core of 0.11 m/s for the first megaplume (MP1) and 0.07 m/s for the second megaplume (MP2). Currents extend beyond the core to a radius of 12-15 km. The centers of the cores are in nearly solid body rotation with relative vorticities of -0.5f (MP2) and potential vorticity anomalies, expressed in units of equivalent relative vorticity, of -0.8f (MP1) and -0.6f (MP2), where f is the Coriolis frequency. The aspect ratio of each megaplume gives a Burger number of 0.22. In terms of these nondimensional numbers, the megaplumes are very similar to eddies of Mediterranean water found in the eastern Atlantic (meddies), despite their very different origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JGRB..119.7389T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JGRB..119.7389T&link_type=ABSTRACT"><span id="translatedtitle">High-resolution near-bottom vector magnetic anomalies over Raven <span class="hlt">Hydrothermal</span> Field, Endeavour Segment, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tivey, Maurice A.; Johnson, H. Paul; Salmi, Marie S.; Hutnak, Michael</p> <p>2014-10-01</p> <p>High-resolution, near-bottom vector magnetic data were collected by remotely operated vehicle Jason over the Raven <span class="hlt">hydrothermal</span> vent field (47°57.3'N 129°5.75'W) located north of Main Endeavour vent field on the Endeavour segment of the Juan de Fuca Ridge. The survey was part of a comprehensive heat flow study of the Raven <span class="hlt">site</span> using innovative thermal blanket technology to map the heat flux and crustal fluid pathways around a solitary <span class="hlt">hydrothermal</span> vent field. Raven <span class="hlt">hydrothermal</span> activity is presently located along the western axial valley wall, while additional inactive <span class="hlt">hydrothermal</span> deposits are found to the NW on the upper rift valley wall. Magnetic inversion results show discrete areas of reduced magnetization associated with both active and inactive <span class="hlt">hydrothermal</span> vent deposits that also show high conductive heat flow. Higher spatial variability in the heat flow patterns compared to the magnetization is consistent with the heat flow reflecting the currently active but ephemeral thermal environment of fluid flow, while crustal magnetization is representative of the static time-averaged effect of <span class="hlt">hydrothermal</span> alteration. A general NW to SE trend in reduced magnetization across the Raven area correlates closely with the distribution of <span class="hlt">hydrothermal</span> deposits and heat flux patterns and suggests that the fluid circulation system at depth is likely controlled by local crustal structure and magma chamber geometry. Magnetic gradient tensor components computed from vector magnetic data improve the resolution of the magnetic anomaly source and indicate that the <span class="hlt">hydrothermally</span> altered zone directly beneath the Raven <span class="hlt">site</span> is approximately 15 × 106 m3 in volume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GGG....13.AF04L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GGG....13.AF04L"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> activity in the Northwest Lau Backarc Basin: Evidence from water column measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lupton, J. E.; Arculus, R. J.; Resing, J.; Massoth, G. J.; Greene, R. R.; Evans, L. J.; Buck, N.</p> <p>2012-05-01</p> <p>The Northwest Lau Backarc Basin, consisting of the Northwest Lau Spreading Center (NWLSC) and the Rochambeau Rifts (RR), is unique in having elevated 3He/4He ratios (up to 28 Ra) in the erupted lavas, clearly indicating a hot spot or ocean island basalt (OIB)-type signature. This OIB-type helium signature does not appear in any other part of the Lau Basin. Water column plume surveys conducted in 2008 and 2010 identified several <span class="hlt">sites</span> of active <span class="hlt">hydrothermal</span> discharge along the NWLSC-RR and showed that the incidence of <span class="hlt">hydrothermal</span> activity is high, consistent with the high spreading rate of ˜100 mm/year. Hydrocasts into the Central Caldera and Southern Caldera of the NWLSC detected elevated3He/4He (δ3He = 55% and 100%, respectively), trace metals (TMn, TFe), and suspended particles, indicating localized <span class="hlt">hydrothermal</span> venting at these two <span class="hlt">sites</span>. Hydrocasts along the northern rift zone of the NWLSC also had excess δ3He, TMn, and suspended particles suggesting additional <span class="hlt">sites</span> of <span class="hlt">hydrothermal</span> activity. The RR are dominated by Lobster Caldera, a large volcano with four radiating rift zones. Hydrocasts into Lobster Caldera in 2008 detected high δ3He (up to 239%) and suspended particle and TMn signals, indicating active venting within the caldera. A repeat survey of Lobster in 2010 confirmed the <span class="hlt">site</span> was still active two years later. Plumes at Lobster Caldera and Central Caldera have end-member3He/4He ratios of 19 Ra and 11 Ra, respectively, confirming that hot spot-type helium is also present in the <span class="hlt">hydrothermal</span> fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V12D1009Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V12D1009Z"><span id="translatedtitle">Decline of a <span class="hlt">Hydrothermal</span> Vent Field - Escanaba Trough 12 Years Later</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zierenberg, R. A.; Clague, D. A.; Davis, A. S.; Lilley, M. D.; McClain, J. S.; Olson, E. S.; Ross, S. L.; Von Damm, K. L.</p> <p>2001-12-01</p> <p><span class="hlt">Hydrothermal</span> venting was discovered in Escanaba Trough, the southern sediment-covered portion of the Gorda Ridge, in 1988. Large pyrrhotite-rich massive sulfide mounds are abundant at each of the volcanic/intrusive centers that have been investigated in Escanaba Trough, but the only area of known <span class="hlt">hydrothermal</span> venting is the NESCA <span class="hlt">site</span> along the ridge axis at 41\\deg N. <span class="hlt">Hydrothermal</span> fluids venting at 217\\deg C and 108\\deg C were sampled in 1988 on two sulfide mounds separated by about 275 m. The end-member fluid compositions were indistinguishable within analytical errors. Several sulfide mounds were observed in 1988 which had diffusely venting low temperature (< 20\\deg C) fluids that supported extensive vent communities dominated by fields of Ridgia. Nine holes were drilled in the NESCA area in 1996 on ODP Leg 169, including Hole 1036I that penetrated to basaltic basement at 405 m below sea floor (mbsf). Surveys of the area using the drill string camera located only one area of active venting at the same mound where 217\\deg C vent fluids were sampled from two active vents in 1988. Drill hole 1036A was spudded between the two active vents on this sulfide mound (approximately 4 and 8 m away) and penetrated to 115 mbsf. The NESCA <span class="hlt">site</span> was revisited in 2000 using MBARI's R/V Western Flyer and ROV Tiburon. The <span class="hlt">hydrothermal</span> vents appeared essentially identical to observations made from the drill string camera in 1996 despite the presence of a drill hole within meters of the two vents. The maximum vent temperature measured in 2000 was 212\\deg C. Fluid samples have major element and isotopic compositions very similar to those collected in 1988. The vent fluids have higher methane ( ~19 mmol/kg) than those from the geologically similar Middle Valley vent field, but lower values than those at Guaymas Basin. Drill hole 1036A was weakly venting, but the diffuse <span class="hlt">hydrothermal</span> fluids could not be sampled with the equipment available. The walls of the drill hole were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.B32B..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.B32B..02P"><span id="translatedtitle">Bioavailability, Bioaccumulation and Biotransformation of arsenic in coral reef organisms surrounding an arsenic-rich marine shallow-water <span class="hlt">hydrothermal</span> vent system in the coastal waters of Ambitle Island, Papua New Guinea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pichler, T.; Wallschläger, D.; Price, R. E.</p> <p>2009-12-01</p> <p>Marine shallow-water <span class="hlt">hydrothermal</span> systems are often enriched in biologically toxic elements, thus making them ideal natural analogs for coastal anthropogenic pollution. Here, we report our investigation of the bioavailability, bioaccumulation, and biotransformation of <span class="hlt">hydrothermally</span>-derived arsenic into several coral reef organisms from the arsenic-rich marine shallow-water <span class="hlt">hydrothermal</span> system of Tutum Bay, Ambitle Island, in northeastern Papua New Guinea. <span class="hlt">Hydrothermal</span> venting provided bioavailable As by two major pathways throughout Tutum Bay: 1) easily-exchangeable As from <span class="hlt">hydrothermally</span> influenced sediments to as far away as 200 m from focused venting, and 2) in surface seawaters, which may allow for biological uptake by phytoplankton and transfer up the food web. The soft coral Clavularia sp., the calcareous algae Halimeda sp., and the tunicate Polycarpa sp. collected from the <span class="hlt">hydrothermal</span> area each displayed distinctly higher (up to 20 times) total arsenic compared to the control <span class="hlt">site</span>, with increasing trends while approaching focused <span class="hlt">hydrothermal</span> venting. Organic and inorganic arsenic species were extracted intact from the tissues of each organism, separated by anion exchange chromatography, and analyzed by inductively-coupled plasma-dynamic reaction cell-mass spectrometry. Overall, speciation patterns for Clavularia were similar for the control <span class="hlt">site</span> versus the <span class="hlt">hydrothermal</span> <span class="hlt">site</span>, although the concentrations were much higher. Elevated concentrations of DMA and cationic forms of arsenic, most likely AB, in Clavularia, both from the control <span class="hlt">site</span> and from the <span class="hlt">hydrothermal</span> area suggest its metabolic pathway is not altered due to <span class="hlt">hydrothermal</span> activity, and is similar to other marine organisms. Arsenic speciation patterns in Polycarpa were also similar for both <span class="hlt">sites</span>, and suggests uptake of arsenic via food chain, containing neither As(III) nor As(V), but abundant excluded As and DMA. It is unclear if methylation is taking place within this organism or prior to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13A1712Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1712Y"><span id="translatedtitle">What is the constraint on formation of oil-starved <span class="hlt">hydrothermal</span> systems in the sediment-rich Okinawa Trough, southwestern Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamanaka, T.; Akashi, H.; Mitsunari, T.</p> <p>2012-12-01</p> <p>Petroleum generation associated with seafloor <span class="hlt">hydrothermal</span> systems was first identified at the Guaymas Basin, Gulf of California in 1978 (Simoneit et al., 1979). Since the first discovery, <span class="hlt">hydrothermal</span> petroleums have been discovered at other seafloor <span class="hlt">hydrothermal</span> fields, Escanaba Trough, Middle Valley, and the Red Sea, where thick sedimentary layer overlay the active spreading center. Simoneit (1990) suggested that <span class="hlt">hydrothermal</span> petroleum can be occurred any <span class="hlt">hydrothermal</span> systems as a result of interaction between hot <span class="hlt">hydrothermal</span> fluid and organic mater in the sedimentary layer. In the middle Okinawa Trough, where typical sediment-hosted <span class="hlt">hydrothermal</span> systems distribute, occurrence of <span class="hlt">hydrothermal</span> petroleum has not been found. In 2010 IODP Exp. 331 had been performed, and then five <span class="hlt">sites</span> were drilled at the Iheya North <span class="hlt">hydrothermal</span> system. However, <span class="hlt">hydrothermal</span> petroleum generation has not been reported even at that time. On the other hand, significant <span class="hlt">hydrothermal</span> petroleum generation has been observed at a shallow-seafloor <span class="hlt">hydrothermal</span> system in the Kagoshima Bay, north extension of Okinawa Trough (Yamanaka et al., 1999). It is an interesting subject why <span class="hlt">hydrothermal</span> petroleum can not be found in the Okinawa Trough. So we considered what is the most critical constraint on occurrence of <span class="hlt">hydrothermal</span> petroleum based on comparison with the well known <span class="hlt">hydrothermal</span> fields occurred <span class="hlt">hydrothermal</span> petroleum. Three major control factors for petroleum generation at seafloor <span class="hlt">hydrothermal</span> systems are expected; (i) temperature, (ii) elapsed time, (iii) type of sediment. High temperature is essential for maturation of organic matter, but under extremely high temperature condition pyrolysis to gaseous hydrocarbon and other low-molecular weight product may be prevailed. Dissolved organic matter (DOM) and methane concentrations may reflect the temperature condition, because methane generation may continue under extreme condition but DOM, especially low-molecular weight organic acid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5972807','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5972807"><span id="translatedtitle">Geothermal-energy files in computer storage: <span class="hlt">sites</span>, cities, and industries</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>O'Dea, P.L.</p> <p>1981-12-01</p> <p>The <span class="hlt">site</span>, city, and industrial files are described. The data presented are from the <span class="hlt">hydrothermal</span> <span class="hlt">site</span> file containing about three thousand records which describe some of the principal physical features of <span class="hlt">hydrothermal</span> resources in the United States. Data elements include: latitude, longitude, township, range, section, surface temperature, subsurface temperature, the field potential, and well depth for commercialization. (MHR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP44A..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP44A..04B"><span id="translatedtitle">The use of high resolution ground and airborne magnetic surveys to evaluate the geometry of <span class="hlt">hydrothermal</span> alteration zones over volcanic provinces (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouligand, C.; Glen, J. M.</p> <p>2013-12-01</p> <p>Geophysical methods can provide critical constraints on the distribution and volume of <span class="hlt">hydrothermal</span> alteration, important parameters in understanding the evolution of geothermal systems. Because <span class="hlt">hydrothermal</span> alteration modifies the magnetic properties of the volcanic substratum, magnetic surveys can be used to provide constraints on the distribution of <span class="hlt">hydrothermal</span> alteration at depth. Using Yellowstone caldera as an example, we show that both ground and airborne magnetic surveys can be used to map and assess the volume of <span class="hlt">hydrothermal</span> alteration. Ground magnetic surveys over unaltered volcanic terranes display high-amplitude, short-wavelength anomalies, in contrast to smooth, subdued magnetic anomalies over volcanic substrata demagnetized by <span class="hlt">hydrothermal</span> alteration. We use this contrast to map areas of <span class="hlt">hydrothermal</span> alteration in detail. Inverse methods applied to high-resolution airborne and ground magnetic data can be used to create three-dimensional models of the distribution of magnetization and thus illuminate the geometry of <span class="hlt">hydrothermal</span> alteration. Because of the non-uniqueness of potential fields, the construction of inverse models requires simplifying assumptions on the distribution of magnetization, knowledge of induced and remanent magnetization of fresh and altered geological units, and detailed geological and geophysical data. Within the three <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> that we investigated in Yellowstone National Park, subdued short-wavelength signal indicates pervasive demagnetization (alteration) of the shallow substratum that extends over larger areas than initially mapped by geology. These data also reveal that the largest degree of demagnetization (alteration) and maximum thicknesses of demagnetized (altered) substratum, reaching a few hundred meters, are associated with <span class="hlt">hydrothermal</span> vents and with superficial <span class="hlt">hydrothermal</span> alteration. Our three dimensional models of magnetization provide estimates of the volume of buried <span class="hlt">hydrothermal</span> alteration ranging</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5024619','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5024619"><span id="translatedtitle">Marine diagenesis of <span class="hlt">hydrothermal</span> sulfide</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moammar, M.O.</p> <p>1985-01-01</p> <p>An attempt is made to discuss the artificial and natural oxidation and hydrolysis of <span class="hlt">hydrothermal</span> sulfide upon interaction with normal seawater. Synthetic and natural ferrosphalerite particles used in kinetic oxidation and hydrolysis studies in seawater develop dense, crystalline coatings consisting of ordered and ferrimagnetic delta-(Fe, Zn)OOH. Due to the formation of this reactive diffusion barrier, the release of Zn into solution decreases rapidly, and sulfide oxidation is reduced to a low rate determined by the diffusion of oxygen through the oxyhydroxide film. This also acts as an efficient solvent for ions such as Zn/sup 2 +/, Ca/sup 2 +/, and possibly Cd/sup 2 +/, which contribute to the stabilization of the delta-FeOOH structure. The oxidation of sulfide occurs in many seafloor spreading areas, such as 21/sup 0/N on the East Pacific Ridge. In these areas the old surface of the sulfide chimneys are found to be covered by an orange stain, and sediment near the base of nonactive vents is also found to consist of what has been referred to as amorphous iron oxide and hydroxide. This thesis also discusses the exceedingly low solubility of zinc in seawater, from delta-(Fe, Zn)OOH and the analogous phase (zinc-ferrihydroxide) and the zinc exchange minerals, 10-A manganate and montmorillonite. The concentrations of all four are of the same magnitude (16, 36.4, and 12 nM, respectively) as the zinc concentration in deep ocean water (approx. 10 nM), which suggests that manganates and montmorillonite with iron oxyhydroxides control zinc concentration in the deep ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031516','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031516"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> nontronite formation at Eolo Seamount (Aeolian volcanic arc, Tyrrhenian Sea)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dekov, V.M.; Kamenov, George D.; Stummeyer, Jens; Thiry, M.; Savelli, C.; Shanks, Wayne C.; Fortin, D.; Kuzmann, E.; Vertes, A.</p> <p>2007-01-01</p> <p>A sediment core containing a yellowish-green clay bed was recovered from an area of extensive <span class="hlt">hydrothermal</span> deposition at the SE slope of the Eolo Seamount, Tyrrhenian Sea. The clay bed is composed of pure nontronite (described for the first time in the Tyrrhenian Sea), which appears to be the most aluminous nontronite ever found among the seafloor <span class="hlt">hydrothermal</span> deposits. The high Al content suggests precipitation from Al-containing <span class="hlt">hydrothermal</span> solutions. The REE distribution of the Eolo nontronite has a V-shape pattern. The heavy REE enrichment is in part due to their preferential partitioning in the nontronite structure. This enrichment was possibly further enhanced by the HREE preferential sorption on bacterial cell walls. The light REE enrichment is the result of scavenging uptake by one of the nontronite precursors, i.e., poorly-ordered Fe-oxyhydroxides, from the <span class="hlt">hydrothermal</span> fluids. Oxygen isotopic composition of the nontronite yields a formation temperature of 30????C, consistent with a low-temperature <span class="hlt">hydrothermal</span> origin. The relatively radiogenic Nd isotopic signature of the nontronite compared to the present-day Mediterranean seawater indicates that approximately half of Nd, and presumably the rest of the LREE, are derived from local volcanic sources. On the other hand, 87Sr/86Sr is dominated by present-day seawater Sr. Scanning electron microscopy investigation revealed that the nontronite is composed of aggregates of lepispheres and tube-like filaments, which are indicative of bacteria assisted precipitation. Bacteria inhabiting this <span class="hlt">hydrothermal</span> <span class="hlt">site</span> likely acted as reactive geochemical surfaces on which poorly-ordered <span class="hlt">hydrothermal</span> Fe-oxyhydroxides and silica precipitated. Upon aging, the interactions of these primary <span class="hlt">hydrothermal</span> precipitates coating bacterial filaments and cell walls likely led to the formation of nontronite. Finally, the well-balanced interlayer and layer charges of the crystal lattice of seafloor <span class="hlt">hydrothermal</span> nontronite decrease its</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/624049','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/624049"><span id="translatedtitle">CO{sub 2} supply from deep-sea <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shitashima, Kiminori</p> <p>1998-07-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> systems are aimed as an on-<span class="hlt">site</span> field analysis on the behavior and diffusion of CO{sub 2} in deep ocean. Through ocean ridge volcanism, a large amount of elements including carbon as a form of CO{sub 2} are supplied to deep ocean. <span class="hlt">Hydrothermal</span> vent fluids at highly enriched in CO{sub 2} and show low pH ({approximately} pH 3) relative to seawater. Total carbonate, total CO{sub 2} in seawater, and pH were determined in samples at <span class="hlt">hydrothermal</span> active area in S-EPR. The concentration of total carbonate and pH in the <span class="hlt">hydrothermal</span> fluid samples ranged from 16 to 5 mM and from 3.1 to 7.6, respectively. The <span class="hlt">hydrothermal</span> fluids discharged from the vents were rapidly diluted with ambient seawater, therefore total carbonate concentration and pH value in the plume waters become close to that of ambient seawater near the vents. The positive anomaly of total carbonate and negative anomaly of pH associated with <span class="hlt">hydrothermal</span> plumes were observed on the seafloor along S-EPR axis. The diffusion of total carbonate plumes both westward and eastward in the bottom water along 15{degree}S across the S-EPR were also detected, but pH anomalies were not obtained in the plume. These suggest the possibility of discharging of CO{sub 2} through <span class="hlt">hydrothermal</span> systems to the ocean. Recent estimation of CO{sub 2} fluxes to the ocean through MOR was calculated at 0.7--15 {times} 10{sup 12} mol C year{sup {minus}1}. These values are 3--4 orders of magnitude smaller than the annual CO{sub 2} fluxes through terrestrial and marine respiration, therefore the importance of CO{sub 2} input from MOR on oceanic carbon cycle is thus minimal on shorter-term time scale. However, the CO{sub 2} input from MOR is significant at 10{sup 6}--10{sup 7} years scales, and CO{sub 2} concentration in <span class="hlt">hydrothermal</span> fluids at hotspot and back-arc basin is 10--100 times higher than that of MOR. The flux of CO{sub 2} from deep-sea <span class="hlt">hydrothermal</span> systems to the ocean may be significant.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.V23A2385I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.V23A2385I"><span id="translatedtitle">Geomicrobiology of <span class="hlt">Hydrothermal</span> Vents in Yellowstone Lake: Phylogenetic and Functional Analysis suggest Importance of Geochemistry (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inskeep, W. P.; Macur, R.; Jay, Z.; Clingenpeel, S.; Tenney, A.; Lavalvo, D.; Shanks, W. C.; McDermott, T.; Kan, J.; Gorby, Y.; Morgan, L. A.; Yooseph, S.; Varley, J.; Nealson, K.</p> <p>2010-12-01</p> <p> outflow channels of YNP. Analysis of functional genes present in the consensus metagenome sequence representing these populations indicate metabolic potential for oxidation of reduced sulfur and hydrogen, both of which are present at high concentrations in these vent ecosystems. Metagenome sequence of biomass associated with sediments from <span class="hlt">hydrothermal</span> vents at Mary Bay (50 m depth) suggest greater archaeal and bacterial diversity in this environment, which may be due to higher concentrations of hydrogen, iron, and manganese measured in these environments. Results from metagenome sequence and modest 16S rRNA gene surveys from <span class="hlt">hydrothermal</span> vent biomass indicate that several groups of novel thermophilic archaea inhabit these <span class="hlt">sites</span>, and in many cases, are represented by organisms not found in YNP terrestrial geothermal environments that have been characterized to date. The <span class="hlt">hydrothermal</span> vents from Inflated Plain and West Thumb indicate a linkage between various geochemical attributes (sulfide, hydrogen) and the metabolic potential associated with dominant Aquificales populations present in these communities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70035042','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70035042"><span id="translatedtitle">Peptide synthesis in early earth <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lemke, K.H.; Rosenbauer, R.J.; Bird, D.K.</p> <p>2009-01-01</p> <p>We report here results from experiments and thermodynamic calculations that demonstrate a rapid, temperature-enhanced synthesis of oligopeptides from the condensation of aqueous glycine. Experiments were conducted in custom-made <span class="hlt">hydrothermal</span> reactors, and organic compounds were characterized with ultraviolet-visible procedures. A comparison of peptide yields at 260??C with those obtained at more moderate temperatures (160??C) gives evidence of a significant (13 kJ ?? mol-1) exergonic shift. In contrast to previous <span class="hlt">hydrothermal</span> studies, we demonstrate that peptide synthesis is favored in <span class="hlt">hydrothermal</span> fluids and that rates of peptide hydrolysis are controlled by the stability of the parent amino acid, with a critical dependence on reactor surface composition. From our study, we predict that rapid recycling of product peptides from cool into near-supercritical fluids in mid-ocean ridge <span class="hlt">hydrothermal</span> systems will enhance peptide chain elongation. It is anticipated that the abundant <span class="hlt">hydrothermal</span> systems on early Earth could have provided a substantial source of biomolecules required for the origin of life. Astrobiology 9, 141-146. ?? 2009 Mary Ann Liebert, Inc. 2009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080013167','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080013167"><span id="translatedtitle">Sample Return from Ancient <span class="hlt">Hydrothermal</span> Springs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allen, Carlton C.; Oehler, Dorothy Z.</p> <p>2008-01-01</p> <p><span class="hlt">Hydrothermal</span> spring deposits on Mars would make excellent candidates for sample return. Molecular phylogeny suggests that that life on Earth may have arisen in <span class="hlt">hydrothermal</span> settings [1-3], and on Mars, such settings not only would have supplied energy-rich waters in which martian life may have evolved [4-7] but also would have provided warm, liquid water to martian life forms as the climate became colder and drier [8]. Since silica, sulfates, and clays associated with <span class="hlt">hydrothermal</span> settings are known to preserve geochemical and morphological remains of ancient terrestrial life [9-11], such settings on Mars might similarly preserve evidence of martian life. Finally, because formation of <span class="hlt">hydrothermal</span> springs includes surface and subsurface processes, martian spring deposits would offer the potential to assess astrobiological potential and hydrological history in a variety of settings, including surface mineralized terraces, associated stream deposits, and subsurface environments where organic remains may have been well protected from oxidation. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data [12-14]. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel, and based on these new data, we have interpreted several features in Vernal Crater, Arabia Terra as ancient <span class="hlt">hydrothermal</span> springs [15, 16].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6916819','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6916819"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> processing of new fly ash cement</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jiang, W.; Roy, D.M. )</p> <p>1992-04-01</p> <p>The recent Mount Pinatubo volcanic eruption in the Philippines, in which at least 268 people died, shows that volcanic eruptions can be highly destructive. The eruption shot ash and debris over the countryside; six towns near the volcano faced a high risk of devastating mudslides, and nearly 2000 U.S. service members and their families were evacuated from two nearby military bases. However, this paper reports that not all the consequences of volcanic eruptions are bad. Under <span class="hlt">hydrothermal</span> conditions, volcanic ash can be transformed into zeolitic tuff and, eventually, into clay minerals that constitute agricultural soils. The Materials Research Laboratory (MRL) has recently used some artificial pozzolanas (fly ash) that when mixed with lime, under <span class="hlt">hydrothermal</span> conditions, also produced a new type of cementitious material. This was categorized as a new fly ash cement. The formation of a new <span class="hlt">hydrothermally</span> treated wood-fiber-reinforced composite has also been demonstrated. It is apparent, however, that with respect to concerns about detailed knowledge of the reactivity of calcium silicate-based materials under <span class="hlt">hydrothermal</span> conditions, the application of the technology far outweighs the understanding of the underlying principles of reactivity. It would seem that an understanding of reactions on the molecular level is just beginning, and that work on <span class="hlt">hydrothermal</span> reactions is still a potentially lucrative area of research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016266','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016266"><span id="translatedtitle">Hydrocarbon geochemistry of <span class="hlt">hydrothermally</span> generated petroleum from Escanaba trough, offshore Californi U.S.A.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kvenvolden, K.A.; Rapp, J.B.; Hostettler, F.D.</p> <p>1990-01-01</p> <p>In 1986, three samples of sulfide-rich sediments, impregnated with <span class="hlt">hydrothermally</span> derived, asphaltic petroleum, were recovered in a dredge and by submersible from Escanaba Trough, the sediment-covered, southern end of the Gorda Ridge spreading axis, offshore northern California. The molecular distributions of hydrocarbons in the two pyrrhotite-rich samples recovered by submersible are similar and compare well the hydrocarbon composition of the first pyrrhotite-rich samples containing petroleum discovered at a 1985 dredge <span class="hlt">site</span> about 30 km to the south of the <span class="hlt">site</span> of the submersible dive. In contrast, the 1986 dredge sample, composed of a polymetallic assemblage of sulfides, containes petroleum in which the distribution of hydrocarbons indicates a slightly higher of maturity relative to the other samples. The observation that petroleum of variable composition occurs with metallic sulfides at two and probably more distinct <span class="hlt">site</span> indicates that petroleum generation may be a common process in the <span class="hlt">hydrothermally</span> active Escanaba Trough. ?? 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6191629','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6191629"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> vent clam and tube worm /sup 13/C//sup 12/C: further evidence of nonphotosynthetic food sources</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rau, G.H.</p> <p>1981-07-17</p> <p>The stable carbon isotope ratios in clam mantle tissues taken from both Galapagos and 21/sup 0/N <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> were similar to the unusually low ratios of carbon-13 to carbon-12 previously reported for a Galapagos <span class="hlt">hydrothermal</span> vent mussel. In marked contrast to these bivalues, vestimentiferan worm tissues from a Galapagos vent had isotope ratios that were higher than those of open ocean biota. These observations suggest that more than one nonpelagic and nonphotosynthetic carbon fixation pathway is of nutritional importance to vent animals, and that at least one of these pathways is common to two geographically separated vent <span class="hlt">sites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6889436','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6889436"><span id="translatedtitle">Exploratory benefit-cost analysis of environmental controls on <span class="hlt">hydrothermal</span> energy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scott, M.J.; Wells, K.D.; Currie, J.W.; King, M.J.</p> <p>1981-02-01</p> <p>A study of the value of environmental benefits generated by environmental regulation of <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> was initiated to compare these benefits with the estimated costs of regulation. Primary objectives were to 1) evaluate the environmental damages caused by unregulated <span class="hlt">hydrothermal</span> resource development, 2) use existing environmental and economic data to estimate the dollar value of preventing expected environmental damages at two <span class="hlt">sites</span>, and 3) compare the benefits and costs of preventing the damages. The <span class="hlt">sites</span> chosen for analyses were in the Imperial Valley at Heber and Niland, California. Reasons for this choice were 1) there is a high level of commercial interest in developing the Heber known geothermal resource area (KGRA) and the Salton Sea KGRA; 2) the potential for environmental damage is high; 3) existing data bases for these two <span class="hlt">sites</span> are more comprehensive than at other <span class="hlt">sites</span>. The primary impacts analyzed were those related to hydrogen sulfide (H/sub 2/S) emissions and those related to disposal of spent <span class="hlt">hydrothermal</span> brine. (MHR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B11I0562B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B11I0562B"><span id="translatedtitle">Marine Subsurface Microbial Communities Across a <span class="hlt">Hydrothermal</span> Gradient in Okinawa Trough Sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandt, L. D.; Hser Wah Saw, J.; Ettema, T.; House, C. H.</p> <p>2015-12-01</p> <p>IODP Expedition 331 to the Okinawa backarc basin provided an opportunity to study the microbial stratigraphy within the sediments surrounding a <span class="hlt">hydrothermal</span> vent. The Okinawa backarc basin is a sedimented region of the seafloor located on a continental margin, and also hosts a <span class="hlt">hydrothermal</span> network within the subsurface. <span class="hlt">Site</span> C0014 within the Iheya North <span class="hlt">hydrothermal</span> field is located 450 m east of the active vent and has a surface temperature of 5°C with no evidence of <span class="hlt">hydrothermal</span> alteration within the top 10 meters below sea floor (mbsf). Temperature increases with depth at an estimated rate of 3°C/m and transitions from non-<span class="hlt">hydrothermal</span> margin sediments to a <span class="hlt">hydrothermally</span> altered regime below 10 mbsf. In this study, we utilized deep 16S rRNA sequencing of DNA from IODP Expedition 331 <span class="hlt">Site</span> C0014 sediment horizons in order to assess diversity throughout the sediment column as well as determine the potential limits of the biosphere. Analysis of the amplicon data shows a shift over 15 mbsf from a heterogeneous community of cosmopolitan marine subsurface taxa toward an archaeal-dominated community in the deepest horizons of the predicted biosphere. Notably, the phylum Chloroflexi represents a substantial taxon through most horizons, where it appears to be replaced below 10 mbsf by punctuations of thermophilic and methanotrophic Archaea and Miscellaneous Crenarchaeotic Group abundances. DNA from the aforementioned transition horizons was further analyzed using metagenomic sequencing. Preliminary taxonomic analysis of the metagenomic data agrees well with amplicon data in capturing the shift in relative abundance of Archaea increasing with depth. Additionally, reverse gyrase, a gene found exclusively in hyperthermophilic microorganisms, was recovered only in the metagenome of the deepest horizon. A BLAST search of this protein sequence against the GenBank non-redudnant protein database produced top hits with reverse gyrase from Thermococcus and Pyrococcus, which are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040141979&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dorganic%2Bsynthesis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040141979&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dorganic%2Bsynthesis"><span id="translatedtitle">Lipid synthesis under <span class="hlt">hydrothermal</span> conditions by Fischer-Tropsch-type reactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McCollom, T. M.; Ritter, G.; Simoneit, B. R.</p> <p>1999-01-01</p> <p>Ever since their discovery in the late 1970's, mid-ocean-ridge <span class="hlt">hydrothermal</span> systems have received a great deal of attention as a possible <span class="hlt">site</span> for the origin of life on Earth (and environments analogous to mid-ocean-ridge <span class="hlt">hydrothermal</span> systems are postulated to have been <span class="hlt">sites</span> where life could have originated or Mars and elsewhere as well). Because no modern-day terrestrial <span class="hlt">hydrothermal</span> systems are free from the influence of organic compounds derived from biologic processes, laboratory experiments provide the best opportunity for confirmation of the potential for organic synthesis in <span class="hlt">hydrothermal</span> systems. Here we report on the formation of lipid compounds during Fischer-Tropsch-type synthesis from aqueous solutions of formic acid or oxalic acid. Optimum synthesis occurs in stainless steel vessels by heating at 175 degrees C for 2-3 days and produces lipid compounds ranging from C2 to > C35 which consist of n-alkanols, n-alkanoic acids, n-alkenes, n-alkanes and alkanones. The precursor carbon sources used are either formic acid or oxalic acid, which disproportionate to H2, CO2 and probably CO. Both carbon sources yield the same lipid classes with essentially the same ranges of compounds. The synthesis reactions were confirmed by using 13C labeled precursor acids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26PSL.270..157B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26PSL.270..157B"><span id="translatedtitle">The distribution and stabilisation of dissolved Fe in deep-sea <span class="hlt">hydrothermal</span> plumes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bennett, Sarah A.; Achterberg, Eric P.; Connelly, Douglas P.; Statham, Peter J.; Fones, Gary R.; German, Christopher R.</p> <p>2008-06-01</p> <p>We have conducted a study of <span class="hlt">hydrothermal</span> plumes overlying the Mid-Atlantic Ridge near 5° S to investigate whether there is a significant export flux of dissolved Fe from <span class="hlt">hydrothermal</span> venting to the oceans. Our study combined measurements of plume-height Fe concentrations from a series of 6 CTD stations together with studies of dissolved Fe speciation in a subset of those samples. At 2.5 km down plume from the nearest known vent <span class="hlt">site</span> dissolved Fe concentrations were ˜ 20 nM. This is much higher than would be predicted from a combination of plume dilution and dissolved Fe(II) oxidation rates, but consistent with stabilisation due to the presence of organic Fe complexes and Fe colloids. Using Competitive Ligand Exchange-Cathodic Stripping Voltammetry (CLE-CSV), stabilised dissolved Fe complexes were detected within the dissolved Fe fraction on the edges of one non-buoyant <span class="hlt">hydrothermal</span> plume with observed ligand concentrations high enough to account for stabilisation of ˜ 4% of the total Fe emitted from the 5° S vent <span class="hlt">sites</span>. If these results were representative of all <span class="hlt">hydrothermal</span> systems, submarine venting could provide 12-22% of the global deep-ocean dissolved Fe budget.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17123405','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17123405"><span id="translatedtitle">Protist genetic diversity in the acidic <span class="hlt">hydrothermal</span> environments of Lassen Volcanic National Park, USA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brown, Patricia B; Wolfe, Gordon V</p> <p>2006-01-01</p> <p>We examined eukaryote genetic diversity in the <span class="hlt">hydrothermal</span> environments of Lassen Volcanic National Park (LVNP), Northern California. We sampled <span class="hlt">hydrothermal</span> areas of the Bumpass Hell, Sulfur Works, Devil's Kitchen, and Boiling Springs Lake <span class="hlt">sites</span>, all of which included diverse acidic pools, mud pots, and streams with visible algal mats and biofilms. Temperatures varied from 15 to 85 degrees C and pH from 1.7 to 5.8. DNA extraction methods compared by denaturing gradient gel electrophoresis fingerprinting exhibited similar patterns, and showed limited diversity of eukaryotic small subunit (SSU) rRNA genes compared with prokaryotes. We successfully amplified eukaryotic SSU rRNA genes from most environments up to 68 degrees C. Cloned rDNA sequences reveal acidophilic protists dominate eukaryotes in LVNP <span class="hlt">hydrothermal</span> environments. Most <span class="hlt">sites</span> showed phototrophic assemblages dominated by chlorophytes and stramenopiles (diatoms and chrysophytes). Heterotrophic taxa, though less abundant, included diverse alveolates (ciliates), amoebae, and flagellates. Fungi were also found at most <span class="hlt">sites</span>, and metazoans (hexapods, nematodes, platyhelminths) were sometimes detected in less acidic environments, especially in algal mats. While many cloned rDNA sequences showed 95%-99% identity to known acidophilic isolates or environmental clones from other acidic <span class="hlt">sites</span> (Rio Tinto), sequence diversity generally declined both with decreasing pH and increasing temperature, and both were controlling physical variables on the abundance and distribution of organisms at our <span class="hlt">sites</span>. However, a pool at 68 degrees C with pH 1.7 yielded the greatest number of distinct sequences. While some were likely contaminants from nearby cooler <span class="hlt">sites</span>, we suggest that Lassen's acidic <span class="hlt">hydrothermal</span> features may harbor novel protists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1060958','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1060958"><span id="translatedtitle">Characterization of advanced preprocessed materials (<span class="hlt">Hydrothermal</span>)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rachel Emerson; Garold Gresham</p> <p>2012-09-01</p> <p>The initial <span class="hlt">hydrothermal</span> treatment parameters did not achieve the proposed objective of this effort; the reduction of intrinsic ash in the corn stover. However, liquid fractions from the 170°C treatments was indicative that some of the elements routinely found in the ash that negatively impact the biochemical conversion processes had been removed. After reviewing other options for facilitating ash removal, sodium-citrate (chelating agent) was included in the <span class="hlt">hydrothermal</span> treatment process, resulting in a 69% reduction in the physiological ash. These results indicated that chelation –<span class="hlt">hydrothermal</span> treatment is one possible approach that can be utilized to reduce the overall ash content of feedstock materials and having a positive impact on conversion performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.9266G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.9266G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Ni Prospectivity Analysis of Tasmania, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzalez-Alvalez, I.; Porwal, A.; McCuaig, T. C.</p> <p>2009-04-01</p> <p>Tasmania contains the largest <span class="hlt">hydrothermal</span> Ni deposit in Australia: Avebury (118,000 Ni metal tonnes). This Devonian deposit was discovered in 1998 in the Dundas geological region, and represents an outstanding example of <span class="hlt">hydrothermal</span> Nickel sulphide mineralization type. Avebury Ni deposit is a system of <span class="hlt">hydrothermal</span> Ni ore bodies. It is hosted by an intensely altered and serpentinized Cambrian ultramafic suite in close proximity to major structural features. The mineralization is considered to be the result of <span class="hlt">hydrothermal</span> scavenging and remobilization of the original nickel content of the mafic/ultramafic rocks in the area, and subsequent re-deposition in favourable structural traps. The mineralization is spatially and temporally related to a large granitic intrusion, the Heemskirk Granite, which is considered to be the source of the <span class="hlt">hydrothermal</span> fluids as well as the necessary thermal gradients for the circulation of the fluids. Tasmania is largely covered by the Jurassic Ferrar Continental Flood basalt Province in the East and presents early Cambrian ultramafic-mafic complexes in the West. The Ferrar large igneous province (LIP) extends over to Antarctica and is related to the Karoo Province in southern Africa that comprises tholeiitic lava flows, sills, and dyke swarms. The Ferrar and Karoo provinces were associated with the same thermal anomaly that was involved in the break up of Gondwana. The presence of mafic/ultramafic rocks in favourable lithological packages and/or structural traps along the margins of the province, as well as several prospective reduced or reactive sedimentary packages within and around the Ferrar indicate that this LIP could represent a novel promising ground for Ni <span class="hlt">hydrothermal</span> exploration. Based on this prospective geological background, a prospectivity analysis for <span class="hlt">hydrothermal</span> Ni deposits was carried out on regional scale for the entire state of Tasmania. A conceptual model of <span class="hlt">hydrothermal</span> nickel mineral system was used to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1113747G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1113747G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Ni Prospectivity Analysis of Tasmania, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzalez-Alvarez, I.; Porwal, A.; McCuaig, T. C.; Maier, W.</p> <p>2009-04-01</p> <p>Tasmania contains the largest <span class="hlt">hydrothermal</span> Ni deposit in Australia: Avebury (118,000 Ni metal tonnes). This Devonian deposit was discovered in 1998 in the Dundas geological region, and consists of a system of <span class="hlt">hydrothermal</span> Ni ore bodies. They are hosted by an intensely altered and serpentinized Cambrian ultramafic suite in close proximity to major structural features. The mineralization is considered to be the result of <span class="hlt">hydrothermal</span> scavenging and remobilization of the original nickel content of mafic/ultramafic rocks in the area, and subsequent re-deposition in favourable structural traps. This is based on the low sulphur, low Cu and Platinum element content of the mineralization. The mineralization is spatially (at the edge) and temporally related to a large granitic intrusion, the Heemskirk Granite, which is considered to be the source of the <span class="hlt">hydrothermal</span> fluids as well as the necessary thermal gradients for the circulation of the fluids. Tasmania is largely covered by the Jurassic Ferrar continental flood basalt province in the East and constrains a number of early Cambrian ultramafic-mafic complexes in the West. The Ferrar large igneous province (LIP) extends over to Antarctica and is temporally and genetically related to the Karoo igneous province in southern Africa that comprises tholeiitic lava flows, sills, and dyke swarms. The Ferrar and Karoo igneous provinces were associated with the same thermal anomaly that was responsible for the break up of eastern Gondwana at ca 180 Ma. Despite of timeframe differences between the Avebury Ni deposits and the Ferrar LIP emplacement, similar geological settings to the Avebury could be duplicated along the Ferrar LIP. The presence of mafic/ultramafic rocks in favourable lithological packages and/or structural traps along the margins of the province indicate that this LIP could represent a possible exploration target for Ni <span class="hlt">hydrothermal</span> deposits. Based on this background, a prospectivity analysis for <span class="hlt">hydrothermal</span> Ni</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21497436','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21497436"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> treatment of electric arc furnace dust.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yu, Bing-Sheng; Wang, Yuh-Ruey; Chang, Tien-Chin</p> <p>2011-06-15</p> <p>In this study, ZnO crystals were fabricated from electric arc furnace dust (EAFD) after alkaline leaching, purification and <span class="hlt">hydrothermal</span> treatment. The effects of temperature, duration, pH, and solid/liquid ratio on ZnO crystal morphology and size were investigated. Results show a high reaction temperature capable of accelerating the dissolution of ZnO precursor, expediting the growth of 1D ZnO, and increasing the L/D ratio in the temperature range of 100-200°C. ZnO crystals with high purity can also be obtained, using the one-step <span class="hlt">hydrothermal</span> treatment with a baffle that depends on the different solubility of zincite and franklinite in the <span class="hlt">hydrothermal</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/674572','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/674572"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> processing of radioactive combustible waste</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Worl, L.A.; Buelow, S.J.; Harradine, D.; Le, L.; Padilla, D.D.; Roberts, J.H.</p> <p>1998-09-01</p> <p><span class="hlt">Hydrothermal</span> processing has been demonstrated for the treatment of radioactive combustible materials for the US Department of Energy. A <span class="hlt">hydrothermal</span> processing system was designed, built and tested for operation in a plutonium glovebox. Presented here are results from the study of the <span class="hlt">hydrothermal</span> oxidation of plutonium and americium contaminated organic wastes. Experiments show the destruction of the organic component to CO{sub 2} and H{sub 2}O, with 30 wt.% H{sub 2}O{sub 2} as an oxidant, at 540 C and 46.2 MPa. The majority of the actinide component forms insoluble products that are easily separated by filtration. A titanium liner in the reactor and heat exchanger provide corrosion resistance for the oxidation of chlorinated organics. The treatment of solid material is accomplished by particle size reduction and the addition of a viscosity enhancing agent to generate a homogeneous pumpable mixture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005Geo....33..153H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005Geo....33..153H"><span id="translatedtitle">Manifestations of <span class="hlt">hydrothermal</span> discharge from young abyssal hills on the fast-spreading East Pacific Rise flank</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haymon, Rachel M.; MacDonald, Ken C.; Benjamin, Sara B.; Ehrhardt, Christopher J.</p> <p>2005-02-01</p> <p>Spectacular black smokers along the mid-ocean-ridge crest represent a small fraction of total <span class="hlt">hydrothermal</span> heat loss from ocean lithosphere. Previous models of measured heat flow suggest that 40% 50% of oceanic <span class="hlt">hydrothermal</span> heat and fluid flux is from young seafloor (0.1 5 Ma) on mid-ocean-ridge flanks. Despite evidence that ridge-flank <span class="hlt">hydrothermal</span> flux affects crustal properties, ocean chemistry, and the deep-sea biosphere, few ridge-flank vent <span class="hlt">sites</span> have been discovered. We describe the first known seafloor expressions of <span class="hlt">hydrothermal</span> discharge from tectonically formed abyssal hills flanking a fast-spreading ridge. Seafloor manifestations of fluid venting from two young East Pacific Rise abyssal hills (0.1 Ma at 10°20‧N, 103°33.2‧W; 0.5 Ma at 9°27‧N, 104°32.3‧W) include fault-scarp <span class="hlt">hydrothermal</span> mineralization and macrofauna; fault-scarp flocculations containing hyperthermophilic microbes; and hilltop sediment mounds and craters possibly created by fluid expulsion. These visible features can be exploited for <span class="hlt">hydrothermal</span> exploration of the vast abyssal hill terrain flanking the mid-ocean ridge and for access to the subseafloor biosphere. Petrologic evidence suggests that abyssal hills undergo repeated episodes of transitory fluid discharge, possibly linked to seismic events, and that fluid exit temperatures can be briefly high enough to transport copper (≥250 °C).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25244359','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25244359"><span id="translatedtitle">Identification and activity of acetate-assimilating bacteria in diffuse fluids venting from two deep-sea <span class="hlt">hydrothermal</span> systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Winkel, Matthias; Pjevac, Petra; Kleiner, Manuel; Littmann, Sten; Meyerdierks, Anke; Amann, Rudolf; Mußmann, Marc</p> <p>2014-12-01</p> <p>Diffuse <span class="hlt">hydrothermal</span> fluids often contain organic compounds such as hydrocarbons, lipids, and organic acids. Microorganisms consuming these compounds at <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> are so far only known from cultivation-dependent studies. To identify potential heterotrophs without prior cultivation, we combined microbial community analysis with short-term incubations using (13)C-labeled acetate at two distinct <span class="hlt">hydrothermal</span> systems. We followed cell growth and assimilation of (13)C into single cells by nanoSIMS combined with fluorescence in situ hybridization (FISH). In 55 °C-fluids from the Menez Gwen <span class="hlt">hydrothermal</span> system/Mid-Atlantic Ridge, a novel epsilonproteobacterial group accounted for nearly all assimilation of acetate, representing the first aerobic acetate-consuming member of the Nautiliales. In contrast, Gammaproteobacteria dominated the (13) C-acetate assimilation in incubations of 37 °C-fluids from the back-arc <span class="hlt">hydrothermal</span> system in the Manus Basin/Papua New Guinea. Here, 16S rRNA gene sequences were mostly related to mesophilic Marinobacter, reflecting the high content of seawater in these fluids. The rapid growth of microorganisms upon acetate addition suggests that acetate consumers in diffuse fluids are copiotrophic opportunists, which quickly exploit their energy sources, whenever available under the spatially and temporally highly fluctuating conditions. Our data provide first insights into the heterotrophic microbial community, catalyzing an under-investigated part of microbial carbon cycling at <span class="hlt">hydrothermal</span> vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7369562','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7369562"><span id="translatedtitle">Geothermal reservoirs in <span class="hlt">hydrothermal</span> convection systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sorey, M.L.</p> <p>1982-01-01</p> <p>Geothermal reservoirs commonly exist in <span class="hlt">hydrothermal</span> convection systems involving fluid circulation downward in areas of recharge and upwards in areas of discharge. Because such reservoirs are not isolated from their surroundings, the nature of thermal and hydrologic connections with the rest of the system may have significant effects on the natural state of the reservoir and on its response to development. Conditions observed at numerous developed and undeveloped geothermal fields are discussed with respect to a basic model of the discharge portion of an active <span class="hlt">hydrothermal</span> convection system. Effects of reservoir development on surficial discharge of thermal fluid are also delineated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMOS12A..04H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMOS12A..04H&link_type=ABSTRACT"><span id="translatedtitle">Parameterization of and Brine Storage in MOR <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoover, J.; Lowell, R. P.; Cummings, K. B.</p> <p>2009-12-01</p> <p>Single-pass parameterized models of high-temperature <span class="hlt">hydrothermal</span> systems at oceanic spreading centers use observational constraints such as vent temperature, heat output, vent field area, and the area of heat extraction from the sub-axial magma chamber to deduce fundamental <span class="hlt">hydrothermal</span> parameters such as total mass flux Q, bulk permeability k, and the thickness of the conductive boundary layer at the base of the system, δ. Of the more than 300 known systems, constraining data are available for less than 10%. Here we use the single pass model to estimate Q, k, and δ for all the seafloor <span class="hlt">hydrothermal</span> systems for which the constraining data are available. Mean values of Q, k, and δ are 170 kg/s, 5.0x10-13 m2, and 20 m, respectively; which is similar to results obtained from the generic model. There is no apparent correlation with spreading rate. Using observed vent field lifetimes, the rate of magma replenishment can also be calculated. Essentially all high-temperature <span class="hlt">hydrothermal</span> systems at oceanic spreading centers undergo phase separation, yielding a low chlorinity vapor and a high salinity brine. Some systems such as the Main Endeavour Field on the Juan de Fuca Ridge and the 9°50’N <span class="hlt">sites</span> on the East Pacific Rise vent low chlorinity vapor for many years, while the high density brine remains sequestered beneath the seafloor. In an attempt to further understand the brine storage at the EPR, we used the mass flux Q determined above, time series of vent salinity and temperature, and the depth of the magma chamber to determine the rate of brine production at depth. We found thicknesses ranging from 0.32 meters to ~57 meters over a 1 km2 area from 1994-2002. These calculations suggest that brine maybe being stored within the conductive boundary layer without a need for lateral transport or removal by other means. We plan to use the numerical code FISHES to further test this idea.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT........46O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT........46O"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> fault zone mapping using seismic and electrical measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Onacha, Stephen Alumasa</p> <p></p> <p>This dissertation presents a new method of using earthquakes and resistivity data to characterize permeable <span class="hlt">hydrothermal</span> reservoirs. The method is applied to field examples from Casa Diablo in the Long Valley Caldera, California; Mt. Longonot, Kenya; and Krafla, Iceland. The new method has significant practical value in the exploration and production of geothermal energy. The method uses P- and S-wave velocity, S-wave polarization and splitting magnitude, resistivity and magnetotelluric (MT) strike directions to determine fracture-porosity and orientation. The conceptual model used to characterize the buried, fluid-circulating fault zones in <span class="hlt">hydrothermal</span> systems is based on geological and fracture models. The method has been tested with field earthquake and resistivity data; core samples; temperature measurements; and, for the case of Krafla, with a drilled well. The use of resistivity and microearthquake measurements is based on theoretical formulation of shared porosity, anisotropy and polarization. The relation of resistivity and a double porosity-operator is solved using a basis function. The porosity-operator is used to generate a correlation function between P-wave velocity and resistivity. This correlation is then used to generate P-wave velocity from 2-D resistivity models. The resistivity models are generated from magnetotelluric (MT) by using the Non-Linear Conjugate Gradient (NLCG) inversion method. The seismic and electrical measurements used come from portable, multi station microearthquake (MEQ) monitoring networks and multi-profile, MT and transient electromagnetic (TEM) observation campaigns. The main conclusions in this dissertation are listed below: (1) Strong evidence exists for correlation between MT strike direction and anisotropy and MEQ S-wave splitting at <span class="hlt">sites</span> close to fluid-filled fracture zones. (2) A porosity operator generated from a double porosity model has been used to generate valid P-wave velocity models from resistivity data. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MinDe.tmp...36B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MinDe.tmp...36B"><span id="translatedtitle">A Palaeoproterozoic multi-stage <span class="hlt">hydrothermal</span> alteration system at Nalunaq gold deposit, South Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle; Bagas, Leon; Thomsen, Tonny B.</p> <p>2016-07-01</p> <p>Nalunaq is an orogenic, high gold grade deposit situated on the Nanortalik Peninsula, South Greenland. Mineralisation is hosted in shear zone-controlled quartz veins, located in fine- and medium-grained amphibolite. The deposit was the <span class="hlt">site</span> of Greenland's only operating metalliferous mine until its closure in 2014, having produced 10.67 t of gold. This study uses a combination of field investigation, petrography and U/Pb zircon and titanite geochronology to define a multi-stage <span class="hlt">hydrothermal</span> alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783-1762-Ma gold-quartz veins are hosted in reactivated shear zones with a <span class="hlt">hydrothermal</span> alteration halo of biotite-arsenopyrite-sericite-actinolite-pyrrhotite(-chlorite-plagioclase-löllingite-tourmaline-titanite), which is best developed in areas of exceptionally high gold grades. Aplite dykes dated to ca. 1762 Ma cross-cut the gold-quartz veins, providing a minimum age for mineralisation. A <span class="hlt">hydrothermal</span> calcite-titanite alteration assemblage is dated to ca. 1766 Ma; however, this alteration is highly isolated, and as a result, its field relationships are poorly constrained. The <span class="hlt">hydrothermal</span> alteration and mineralisation is cut by several generations of ca. 1745-Ma biotite granodiorite accompanied by brittle deformation. A ca. 1745-Ma lower greenschist facies <span class="hlt">hydrothermal</span> epidote-calcite-zoisite alteration assemblage with numerous accessory minerals forms halos surrounding the late-stage fractures. The contrasting <span class="hlt">hydrothermal</span> alteration styles at Nalunaq indicate a complex history of exhumation from amphibolite facies conditions to lower greenschist facies conditions in an orogenic belt which resembles modern Phanerozoic orogens.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=294527','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=294527"><span id="translatedtitle">Biogeochemistry of <span class="hlt">hydrothermally</span> and adjacent non-altered soils</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized seven pedons, developed in <span class="hlt">hydrothermally</span> and adjacent non-<span class="hlt">hydrothermally</span> altered andesitic parent material near Reno, NV. <span class="hlt">Hydrothermally</span> altered soils had considerably lo...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS22C..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS22C..03P"><span id="translatedtitle">Seafloor <span class="hlt">Hydrothermal</span> Activity in the Southern Gulf of California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paduan, J. B.; Clague, D. A.; Caress, D. W.; Lundsten, L.; Zierenberg, R. A.; Troni, G.; Wheat, C. G.; Spelz, R. M.</p> <p>2015-12-01</p> <p>Active <span class="hlt">hydrothermal</span> venting was previously unknown between Guaymas Basin and 21°N on the East Pacific Rise. MBARI AUV surveys and ROV dives in 2012 and 2015 discovered 7 <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> with diverse and varied vent communities within that gap. One field in the Pescadero Basin vents clear shimmering fluids at 3685 m depth and four vigorous black smoker fields and several extinct chimney fields are between 2225 and 2400 m depth on the Alarcón Rise. Low-temperature vent <span class="hlt">sites</span> are present on both of the Pescadero and Tamayo Transforms. The chimneys were discovered in 1-m resolution AUV bathymetric data, with some indicated to be active based on temperature anomalies in the AUV CTD data and confirmed during later ROV dives. The low-temperature vent <span class="hlt">sites</span> on the transform faults were found on ROV dives while exploring young lava flows and sediment hills uplifted by sill intrusions. Pescadero Basin is a deep extensional basin in the southern Gulf. The smooth, subtly faulted floor is filled with at least 150 m of sediment, as determined from sub-bottom profiles collected by the AUV. Three large chimneys (named Auka by our Mexican collaborators) and several broad mounds are located on the SW margin of the basin. Temperatures to 290°C were measured, the fluids are clear, neutral pH, and contain elevated Na. The chimneys are delicate, white, predominantly Ca-carbonate; barite, sparse sulfides, and some aromatic hydrocarbons are also present. Three active vent fields (Ja Sít, Pericú, and Meyibó) at Alarcón Rise are located near the eruptive fissure of an extensive young sheet flow. The fourth field (Tzab-ek) is 1.1 km NW of the axis on older pillow lavas. The largest chimneys are in the Tzab-ek field: 31 and 33 m tall, with flanges and upside-down waterfalls. They rise from a sulfide mound, suggesting a long-lived <span class="hlt">hydrothermal</span> system, in contrast to the near-axis fields where the chimneys grow directly on basalt. The Alarcón chimneys are Zn and Cu-rich sulfides</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B11D..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B11D..01A"><span id="translatedtitle">Microbial Geochemistry in Shallow-Sea <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amend, J. P.; Pichler, T.</p> <p>2006-12-01</p> <p>Shallow-sea <span class="hlt">hydrothermal</span> systems are far more ubiquitous than generally recognized. Approximately 50-60 systems are currently known, occurring world-wide in areas of high heat flow, such as, volcanic island arcs, near-surface mid-ocean ridges, and intraplate oceanic volcanoes. In contrast to deep-sea systems, shallow- sea vent fluids generally include a meteoric component, they experience phase separation near the sediment- water interface, and they discharge into the photic zone (<200 m). They also are characterized by wide ranges in chemical composition, hundreds of redox disequilibria that translate to potential metabolisms, and broad phylogenetic diversity among the thermophilic bacteria and archaea. Perhaps because deep-sea smokers and continental hot springs are visually more stunning, shallow-sea systems are often overlooked study <span class="hlt">sites</span>. We will discuss their particular features that afford unique opportunities in microbial geochemistry. Two of the better studied examples are at Vulcano Island (Italy) and Ambitle Island (Papua New Guinea). The vents and sediment seeps at Vulcano are the "type locality" for numerous cultured hyperthermophiles, including the bacteria Aquifex and Thermotoga, the crenarchaeon Pyrodictium, and the Euryarchaeota Archaeoglobus and Pyrococcus. Isotope-labeled incubation experiments of heated sediments and an array of culturing studies have shown that simple organic compounds are predominantly fermented or anaerobically respired with sulfate. 16S rRNA gene surveys, together with fluorescent in situ hybridization studies, demonstrated the dominance of key thermophilic bacteria and archaea (e.g., Aquificales, Thermotogales, Thermococcales, Archaeoglobales) in the sediments and the presence of a broad spectrum of mostly uncultured crenarchaeota in several vent waters, sediment samples, and geothermal wells. Thermodynamic modeling quantified potential energy yields from aerobic and anaerobic respiration reactions and fermentation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70099756','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70099756"><span id="translatedtitle">The chemistry of <span class="hlt">hydrothermal</span> magnetite: a review</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John</p> <p>2014-01-01</p> <p>Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of <span class="hlt">hydrothermal</span> magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, <span class="hlt">hydrothermal</span> magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in <span class="hlt">hydrothermal</span> magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of <span class="hlt">hydrothermal</span> and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006E%26PSL.245..487R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006E%26PSL.245..487R&link_type=ABSTRACT"><span id="translatedtitle">The first measurements of <span class="hlt">hydrothermal</span> heat output at 9°50‧N, East Pacific Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramondenc, Pierre; Germanovich, Leonid N.; Von Damm, Karen L.; Lowell, Robert P.</p> <p>2006-05-01</p> <p>Despite the importance of the heat output of seafloor <span class="hlt">hydrothermal</span> systems for the Earth's energy budget, <span class="hlt">hydrothermal</span> heat output measurements have been very limited. In this paper, we report the first measurements of <span class="hlt">hydrothermal</span> heat output at the RIDGE 2000 Integrated Study <span class="hlt">Site</span> on the East Pacific Rise. We focused our work on the Bio 9 complex, situated at 9°50'N, where there has been an extensive measurement and sampling program since 1991. This <span class="hlt">site</span> is located along the eruptive fissure of the 1991/1992 event and the <span class="hlt">site</span> of the 1995 earthquake swarm. We made direct measurements of advective heat output at several individual vents and at one <span class="hlt">site</span> of diffuse flow (Tica). Although these data do not describe the complete heat flux picture at this vent field, the data yield a total <span class="hlt">hydrothermal</span> heat output of ˜ 325 ± 160 MW with ˜ 42 ± 21 MW coming from high-temperature vents along this 2 km segment of ridge. This result assumes a diffuse flux similar to that measured at Tica occurs at each high-temperature vent <span class="hlt">site</span>. Our initial measurements thus suggest that the heat output of the low-temperature diffuse venting is approximately 10 times that of the high-temperature vents, but may also be one or two orders of magnitude greater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/138723','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/138723"><span id="translatedtitle">Large-scale in situ heater tests for <span class="hlt">hydrothermal</span> characterization at Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buscheck, T.A.; Wilder, D.G.; Nitao, J.J.</p> <p>1993-01-01</p> <p>To safely and permanently store high-level nuclear waste, the potential Yucca Mountain repository <span class="hlt">site</span> must mitigate the release and transport of radionuclides for tens of thousands of years. In the failure scenario of greatest concern, water would contact a waste package, accelerate its failure rate, and eventually transport radionuclides to the water table. Our analyses indicate that the ambient hydrological system will be dominated by repository-heat-driven <span class="hlt">hydrothermal</span> flow for tens of thousands of years. In situ heater tests are required to provide an understanding of coupled geomechanical-<span class="hlt">hydrothermal</span>-geochemical behavior in the engineered and natural barriers under repository thermal loading conditions. In situ heater tests have been included in the <span class="hlt">Site</span> Characterization Plan in response to regulatory requirements for <span class="hlt">site</span> characterization and to support the validation of process models required to assess the total systems performance at the <span class="hlt">site</span>. Because of limited time, some of the in situ tests will have to be accelerated relative to actual thermal loading conditions. We examine the trade-offs between the limited test duration and generating <span class="hlt">hydrothermal</span> conditions applicable to repository performance during the entire thermal loading cycle, including heating (boiling and dry-out) and cooldown (re-wetting). For in situ heater tests to be applicable to actual repository conditions, a minimum heater test duration of 6-7 yr (including 4 yr of full-power heating) is required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.173...64J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.173...64J"><span id="translatedtitle">Precipitation and growth of barite within <span class="hlt">hydrothermal</span> vent deposits from the Endeavour Segment, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jamieson, John William; Hannington, Mark D.; Tivey, Margaret K.; Hansteen, Thor; Williamson, Nicole M.-B.; Stewart, Margaret; Fietzke, Jan; Butterfield, David; Frische, Matthias; Allen, Leigh; Cousens, Brian; Langer, Julia</p> <p>2016-01-01</p> <p><span class="hlt">Hydrothermal</span> vent deposits form on the seafloor as a result of cooling and mixing of hot <span class="hlt">hydrothermal</span> fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent <span class="hlt">sites</span>, barite (BaSO4) is unique because it requires the direct mixing of Ba-rich <span class="hlt">hydrothermal</span> fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of <span class="hlt">hydrothermal</span> barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, in order to determine the physical and chemical conditions under which barite precipitates within seafloor <span class="hlt">hydrothermal</span> vent systems. Petrographic analyses of 22 barite-rich samples show a range of barite crystal morphologies: dendritic and acicular barite forms near the exterior vent walls, whereas larger bladed and tabular crystals occur within the interior of chimneys. A two component mixing model based on Sr concentrations and 87Sr/86Sr of both seawater and <span class="hlt">hydrothermal</span> fluid, combined with 87Sr/86Sr data from whole rock and laser-ablation ICP-MS analyses of barite crystals indicate that barite precipitates from mixtures containing as low as 17% and as high as 88% <span class="hlt">hydrothermal</span> fluid component, relative to seawater. Geochemical modelling of the relationship between aqueous species concentrations and degree of fluid mixing indicates that Ba2+ availability is the dominant control on mineral saturation. Observations combined with model results support that dendritic barite forms from fluids of less than 40% <span class="hlt">hydrothermal</span> component and with a saturation index greater than ∼0.6, whereas more euhedral crystals form at lower levels of supersaturation associated with greater contributions of <span class="hlt">hydrothermal</span> fluid. Fluid inclusions within barite indicate formation temperatures of between ∼120 °C and 240 °C during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFMOS43C..05X&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFMOS43C..05X&link_type=ABSTRACT"><span id="translatedtitle">Heat flux measured acoustically at Grotto Vent, a <span class="hlt">hydrothermal</span> vent cluster on the Endeavour Segment, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.</p> <p>2013-12-01</p> <p>Over the past several decades, quantifying the heat output has been a unanimous focus of studies at <span class="hlt">hydrothermal</span> vent fields discovered around the global ocean. Despite their importance, direct measurements of <span class="hlt">hydrothermal</span> heat flux are very limited due to the remoteness of most vent <span class="hlt">sites</span> and the complexity of <span class="hlt">hydrothermal</span> venting. Moreover, almost all the heat flux measurements made to date are snapshots and provide little information on the temporal variation that is expected from the dynamic nature of a <span class="hlt">hydrothermal</span> system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://<span class="hlt">sites</span>.google.com/a/uw.edu/covis/) is currently connected to the Endeavour node of the NEPTUNE Canada observatory network (http://www.neptunecanada.ca) to monitor the <span class="hlt">hydrothermal</span> plumes issuing from a vent cluster (Grotto) on the Endeavour Segment of the Juan de Fuca Ridge. COVIS is acquiring a long-term (20-months to date) time series of the vertical flow rate and volume flux of the <span class="hlt">hydrothermal</span> plume above Grotto through the Doppler analysis of the acoustic backscatter data (Xu et al., 2013). We then estimate the plume heat flux from vertical flow rate and volume flux using our newly developed inverse method. In this presentation, we will briefly summarize the derivation of the inverse method and present the heat-flux time series obtained consequently with uncertainty quantification. In addition, we compare our heat-flux estimates with the one estimated from the plume in-situ temperatures measured using a Remotely Operative Vehicle (ROV) in 2012. Such comparison sheds light on the uncertainty of our heat flux estimation. Xu, G., Jackson, D., Bemis, K., and Rona, P., 2013, Observations of the volume flux of a seafloor <span class="hlt">hydrothermal</span> plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040089658&hterms=Archaea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DArchaea','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040089658&hterms=Archaea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DArchaea"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems and the emergence of life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, E. L.</p> <p>1994-01-01</p> <p>The author reviews current thought about life originating in hyperthermophilic microorganisms. Hyperthermophiles obtain food from chemosynthesis of sulfur and have an RNA nucleotide sequence different from bacteria and eucarya. It is postulated that a hyperthermophile may be the common ancestor of all life. Current research efforts focus on the synthesis of organic compounds in <span class="hlt">hydrothermal</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012PhDT.......177G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012PhDT.......177G&link_type=ABSTRACT"><span id="translatedtitle">Serpentinization-assisted deformation processes and characterization of <span class="hlt">hydrothermal</span> fluxes at mid-ocean ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Genc, Gence</p> <p></p> <p>Seafloor <span class="hlt">hydrothermal</span> systems play a significantly important role in Earth’s energy and geochemical budgets and support the existence and development of complex biological ecosystems by providing nutrient and energy to microbial and macrafaunal ecosystems through geochemical fluxes. Heat output and fluid flow are key parameters which characterize <span class="hlt">hydrothermal</span> systems at oceanic spreading centers by constraining models of <span class="hlt">hydrothermal</span> circulation. Although integrated measurements of heat flux in plumes are critically important as well, quantification of heat flux at discrete sources (vent orifices versus patches of seafloor shimmering diffuse flow) from direct measurements is particularly essential for examining the partitioning of heat flow into focused and diffuse components of venting and determining geochemical fluxes from these two modes of flow. <span class="hlt">Hydrothermal</span> heat output also constrains the permeability of young oceanic crust and thickness of the conductive boundary layer that separates magmatic heat source from overlying <span class="hlt">hydrothermal</span> circulation. This dissertation will be fundamentally focused on three main inter-connected topics: (1) the design and development of direct high- or low-temperature heat flow measuring devices for <span class="hlt">hydrothermal</span> systems, (2) the collection of new heat output results on four cruises between 2008 and 2010 at several distinct <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> along mid-ocean ridges (MORs) to estimate total heat output from individual vent structures such as Dante, Hulk or the whole vent field (e.g., Main Endeavour Vent Field (MEF)), the partitioning between focused and diffuse <span class="hlt">hydrothermal</span> venting in MEF, and determination of initial estimates of geochemical flux from diffuse <span class="hlt">hydrothermal</span> fluids which may be influenced by the activity in subsurface biosphere and finally (3) the deformation and uplift associated with serpentinization at MORs and subduction zones. Despite extensive efforts spent for the last couple of decades on heat flow measurement</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.V21A4726X&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.V21A4726X&link_type=ABSTRACT"><span id="translatedtitle">Modeling mid-ocean ridge <span class="hlt">hydrothermal</span> response to earthquakes, tides, and ocean currents: a case study at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, G.; Bemis, K. G.</p> <p>2014-12-01</p> <p>Seafloor <span class="hlt">hydrothermal</span> systems feature intricate interconnections among oceanic, geological, <span class="hlt">hydrothermal</span>, and biological processes. The advent of the NEPTUNE observatory operated by Ocean Networks Canada at the Endeavour Segment, Juan de Fuca Ridge enables scientists to study these interconnections through multidisciplinary, continuous, real-time observations. The multidisciplinary observatory instruments deployed at the Grotto Mound, a major study <span class="hlt">site</span> of the NEPTUNE observatory, makes it a perfect place to study the response of a seafloor <span class="hlt">hydrothermal</span> system to geological and oceanic processes. In this study, we use the multidisciplinary datasets recorded by the NEPTUNE Observatory instruments as observational tools to demonstrate two different aspects of the response of <span class="hlt">hydrothermal</span> activity at the Grotto Mound to geological and oceanic processes. First, we investigate a recent increase in venting temperature and heat flux at Grotto observed by the Benthic and Resistivity Sensors (BARS) and the Cabled Observatory Vent Imaging Sonar (COVIS) respectively. This event started in Mar 2014 and is still evolving by the time of writing this abstract. An initial interpretation in light of the seismic data recorded by a neighboring ocean bottom seismometer on the NEPTUNE observatory suggests the temperature and heat flux increase is probably triggered by local seismic activities. Comparison of the observations with the results of a 1-D mathematical model simulation of <span class="hlt">hydrothermal</span> sub-seafloor circulation elucidates the potential mechanisms underlying <span class="hlt">hydrothermal</span> response to local earthquakes. Second, we observe significant tidal oscillations in the venting temperature time series recorded by BARS and the acoustic imaging of <span class="hlt">hydrothermal</span> plumes by COVIS, which is evidence for <span class="hlt">hydrothermal</span> response to ocean tides and currents. We interpret the tidal oscillations of venting temperature as a result of tidal loading on a poroelastic medium. We then invoke poroelastic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010091026&hterms=cysteine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcysteine','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010091026&hterms=cysteine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcysteine"><span id="translatedtitle">The Biogeochemistry of Sulfur in <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schulte, Mitchell; Rogers, K. L.; DeVincenzi, Donald L. (Technical Monitor)</p> <p>2001-01-01</p> <p>The incorporation of sulfur into many biomolecules likely dates back to the development of the earliest metabolic strategies. Sulfur is common in enzymes and co-enzymes and is an indispensable structural component in many peptides and proteins. Early metabolism may have been heavily influenced by the abundance of sulfide minerals in <span class="hlt">hydrothermal</span> systems. The incorporation of sulfur into many biomolecules likely dates back to the development of the earliest metabolic strategies. Sulfur is common in enzymes and co-enzymes and is an indispensable structural component in many peptides and proteins. Early metabolism may have been heavily influenced by the abundance of sulfide minerals in <span class="hlt">hydrothermal</span> systems. Understanding how sulfur became prevalent in biochemical processes and many biomolecules requires knowledge of the reaction properties of sulfur-bearing compounds. We have previously estimated thermodynamic data for thiols, the simplest organic sulfur compounds, at elevated temperatures and pressures. If life began in <span class="hlt">hydrothermal</span> environments, it is especially important to understand reactions at elevated temperatures among sulfur-bearing compounds and other organic molecules essential for the origin and persistence of life. Here we examine reactions that may have formed amino acids with thiols as reaction intermediates in hypothetical early Earth <span class="hlt">hydrothermal</span> environments. (There are two amino acids, cysteine and methionine, that contain sulfur.) Our calculations suggest that significant amounts of some amino acids were produced in early Earth <span class="hlt">hydrothermal</span> fluids, given reasonable concentrations H2, NH3, H2S and CO. For example, preliminary results indicate that glycine activities as high as 1 mmol can be reached in these systems at 100 C. Alanine formation from propanethiol is also a favorable reaction. On the other hand, the calculated equilibrium log activities of cysteine and serine from propanethiol are -21 and -19, respectively, at 100 C. These results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V31E..04G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V31E..04G"><span id="translatedtitle">Insights From Magnesium Isotopic Compositions on the Oceanic <span class="hlt">Hydrothermal</span> Circulation: Is Seamount Weathering the Solution?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galy, A.; Carder, E.; Elderfield, H.</p> <p>2006-12-01</p> <p>It has been long recognised that the input of Mg in the ocean by river is removed by precipitation of Mg-rich bearing phases, either directly from the ocean such as dolomite or through <span class="hlt">hydrothermal</span> circulation in the oceanic crust. The sampling of <span class="hlt">hydrothermal</span> fluids demonstrated the efficiency of Mg consumption by the alteration of the oceanic crust, even at temperatures as low as 15°. For high-temperature fluids vented through black or white smokers in the vicinity of the ridge, the Mg concentration is up to 50 time lower than in seawater, and the close relationship between chlorine and Mg led to the idea that seawater was feeding the <span class="hlt">hydrothermal</span> system and that Mg is quantitatively removed from it during high-T° alteration, the so called zero Mg hypothesis. Despite some hint for a non zero Mg <span class="hlt">hydrothermal</span> end-member for a handful <span class="hlt">sites</span>, the low concentration of Mg in oceanic <span class="hlt">hydrothermal</span> fluids (around 1 mmol/l) has been mainly attributed to contamination by seawater during the sampling. Here we present Mg isotopic composition of 14 seawater samples from the Atlantic, Pacific and Indian Oceans and the Mediterranean and Red Seas and covering a range of depth of almost 5km and 26 <span class="hlt">hydrothermal</span> fluids from 7 <span class="hlt">sites</span> in the Atlantic and Pacific Oceans with temperature from 15° to 380°C. We find the magnesium isotope composition of seawater to be constant, with a δ^{26}Mg = -0.82±0.10 ‰ relative to the DSM3 standard. This value is consistent with a long residence time for Mg in seawater. In addition, out of the 26 <span class="hlt">hydrothermal</span> fluids studied, more than 58% differ from seawater for their Mg isotopic composition by more than 2σ. This number rises up to 88% at 2σmean level and the shift is systematic with the fluids being either indistinguishable from seawater or enriched in light isotopes by up to 2.4‰ in δ^{26}Mg. This clearly demonstrates that fluids having low Mg concentrations are not solely bearing Mg added by contamination during sampling. The isotopic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P33A1917S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P33A1917S"><span id="translatedtitle">Experimental constraints on <span class="hlt">hydrothermal</span> activities in Enceladus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sekine, Y.; Shibuya, T.; Suzuki, K.; Kuwatani, T.</p> <p>2012-12-01</p> <p>One of the most remarkable findings by the Cassini-Huygens mission is perhaps water-rich plumes erupting from the south-pole region of Enceladus [1]. Given such geological activity and the detection of sodium salts in the plume, the interior of Enceladus is highly likely to contain an interior ocean interacting with the rock core [2]. A primary question regarding astrobiology and planetary science is whether Enceladus has (or had) <span class="hlt">hydrothermal</span> activities in the interior ocean. Because N2 might be formed by thermal dissociation of primordial NH3 [3], the presence of N2 in the plume may be a possible indicator for the presence of <span class="hlt">hydrothermal</span> activities in Enceladus. However, the Cassini UVIS revealed that the plumes do not contain large amounts of N2 [4]. Although these observations may not support the presence of <span class="hlt">hydrothermal</span> activities, whether NH3 dissociation proceeds strongly depends on the kinetics of <span class="hlt">hydrothermal</span> reactions and interactions with the rock components, which remain largely unknown. Furthermore, the Cassini CDA recently showed that small amounts of SiO2 might have been included in the plume dusts [5]. Formation of amorphous SiO2 usually occurs when high-temperature and/or high-pH solution with high concentrations of dissolved SiO2 cools and/or is neutralized. Thus, the presence of SiO2 in the plume dusts may suggest the presence of a temperature and/or pH gradient in the ocean. However, no laboratory experiments have investigated what processes control pH and SiO2 concentrations in <span class="hlt">hydrothermal</span> fluids possibly existing in Enceladus. Here, we show the results of laboratory experiments simulating <span class="hlt">hydrothermal</span> systems on Enceladus. As the initial conditions, we used both aqueous solution of high concentrations (0.01-2%) of NH3 and NaHCO3 and powdered olivine as an analog for the rock components. Our experimental results show that formation of N2 from NH3 is kinetically and thermodynamically inhibited even under high temperature conditions (< 400</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19557339','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19557339"><span id="translatedtitle">Microbial diversity of a sulfide black smoker in main endeavour <span class="hlt">hydrothermal</span> vent field, Juan de Fuca Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Huaiyang; Li, Jiangtao; Peng, Xiaotong; Meng, Jun; Wang, Fengping; Ai, Yuncan</p> <p>2009-06-01</p> <p>Submarine <span class="hlt">hydrothermal</span> vents are among the least-understood habitats on Earth but have been the intense focus of research in the past 30 years. An active <span class="hlt">hydrothermal</span> sulfide chimney collected from the Dudley <span class="hlt">site</span> in the Main Endeavour vent Field (MEF) of Juan de Fuca Ridge was investigated using mineralogical and molecular approaches. Mineral analysis indicated that the chimney was composed mainly of Fe-, Zn-and Cu-rich sulfides. According to phylogenetic analysis, within the Crenarchaeota, clones of the order Desulfurococcales predominated, comprising nearly 50% of archaeal clones. Euryarchaeota were composed mainly of clones belonging to Thermococcales and deep-sea <span class="hlt">hydrothermal</span> vent Euryarchaeota (DHVE), each of which accounted for about 20% of all clones. Thermophilic or hyperthermophilic physiologies were common to the predominant archaeal groups. More than half of bacterial clones belonged to epsilon-Proteobacteria, which confirmed their prevalence in <span class="hlt">hydrothermal</span> vent environments. Clones of Proteobacteria (gamma-, delta-, beta-), Cytophaga-Flavobacterium-Bacteroides (CFB) and Deinococcus-Thermus occurred as well. It was remarkable that methanogens and methanotrophs were not detected in our 16S rRNA gene library. Our results indicated that sulfur-related metabolism, which included sulfur-reducing activity carried out by thermophilic archaea and sulfur-oxidizing by mesophilic bacteria, was common and crucial to the vent ecosystem in Dudley <span class="hlt">hydrothermal</span> <span class="hlt">site</span>. PMID:19557339</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014522','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014522"><span id="translatedtitle">Submarine fissure eruptions and <span class="hlt">hydrothermal</span> vents on the southern Juan de Fuca Ridge: preliminary observations from the submersible Alvin.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Normark, W.R.</p> <p>1986-01-01</p> <p>The submersible Alvin was used to investigate 3 active <span class="hlt">hydrothermal</span> discharge <span class="hlt">sites</span> along the S Juan de Fuca Ridge in September 1984. The <span class="hlt">hydrothermal</span> zones occur within a 10-30m-deep, 30-50m-wide cleft marking the center of the axial valley. This cleft is the eruptive locus for the axial valley. The <span class="hlt">hydrothermal</span> vents coincide with the main eruptive vents along the cleft. Each <span class="hlt">hydrothermal</span> zone has multiple discharge <span class="hlt">sites</span> extending as much as 500m along the cleft. Sulfide deposits occur as clusters (15-100m2 area) of small chimneys (= or <2m high) and as individual and clustered fields of large, branched chimneys (= or <10m high). Recovered sulfide samples are predominantly the tops of chimneys and spires and typically contain more than 80% sphalerite and wurtzite with minor pyrrhotite, pyrite, marcasite, isocubanite, chalcopyrite, anhydrite, anhydrite, and amorphous silica. The associated <span class="hlt">hydrothermal</span> fluids have the highest chlorinity of any reported to date.-Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GeCoA..71.4256B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GeCoA..71.4256B"><span id="translatedtitle">Effects of <span class="hlt">hydrothermal</span> alteration on Pb in the active PACMANUS <span class="hlt">hydrothermal</span> field, ODP Leg 193, Manus Basin, Papua New Guinea: A LA-ICP-MS study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beaudoin, Yannick; Scott, Steven D.; Gorton, Michael P.; Zajacz, Zoltan; Halter, Werner</p> <p>2007-09-01</p> <p>The conventional model of leaching volcanic rocks as a source of metals in a seafloor <span class="hlt">hydrothermal</span> systems has been tested by examining the behavior of Pb and other trace elements during <span class="hlt">hydrothermal</span> alteration. ODP Leg 193 drill <span class="hlt">sites</span> 1188 (Snowcap) and 1189 (Roman Ruins) on Pual Ridge in the eastern Manus Basin offshore eastern Papua New Guinea provide a unique three-dimensional window into an active back-arc <span class="hlt">hydrothermal</span> system. We investigate by means of a LA-ICP-MS microbeam technique the capacity of Pb to be leached from a host volcanic rock exposed to various types and intensities of alteration. Our results are in general agreement with previous studies that utilized bulk analytical techniques but provide a more detailed explanation of the processes. Fresh representative dacitic lavas from the Pual Ridge have an average whole rock Pb content of 5.2 ppm, an average interstitial glass Pb content of 5.6 ppm and an average plagioclase Pb content of 1.0 ppm. Altered matrix samples have highly variable Pb values ranging from 0 to 52.4 ppm. High Pb values in altered samples are associated with a low temperature chlorite and clay mineral assemblage, in some cases overprinted by a high temperature (up to 350 °C) silica-rich "bleaching" alteration. Only the most highly altered matrix samples have REE patterns that differ from the fresh Pual Ridge dacite. This may represent either different lava histories or alteration characteristics that have affected normally immobile REEs. Altered samples with the highest Pb values have similar REE patterns to those of the local unaltered lavas. They are compositionally similar to typical Pual Ridge dacites indicating a genetic relationship between the main regional volcanic suite and the subseafloor <span class="hlt">hydrothermally</span> altered, Pb-enriched material. Relative loss/gain for Pb between the analyzed altered samples and a calculated precursor show a maximum relative gain of 901%. Samples with relative Pb gain from both drill <span class="hlt">sites</span> are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18163874','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18163874"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems in small ocean planets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael</p> <p>2007-12-01</p> <p>We examine means for driving <span class="hlt">hydrothermal</span> activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of <span class="hlt">hydrothermal</span> system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of <span class="hlt">hydrothermal</span> activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive <span class="hlt">hydrothermal</span> fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive <span class="hlt">hydrothermal</span> circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18163874','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18163874"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems in small ocean planets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael</p> <p>2007-12-01</p> <p>We examine means for driving <span class="hlt">hydrothermal</span> activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of <span class="hlt">hydrothermal</span> system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of <span class="hlt">hydrothermal</span> activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive <span class="hlt">hydrothermal</span> fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive <span class="hlt">hydrothermal</span> circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1). PMID:18163874</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15746419','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15746419"><span id="translatedtitle">A serpentinite-hosted ecosystem: the Lost City <span class="hlt">hydrothermal</span> field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelley, Deborah S; Karson, Jeffrey A; Früh-Green, Gretchen L; Yoerger, Dana R; Shank, Timothy M; Butterfield, David A; Hayes, John M; Schrenk, Matthew O; Olson, Eric J; Proskurowski, Giora; Jakuba, Mike; Bradley, Al; Larson, Ben; Ludwig, Kristin; Glickson, Deborah; Buckman, Kate; Bradley, Alexander S; Brazelton, William J; Roe, Kevin; Elend, Mitch J; Delacour, Adélie; Bernasconi, Stefano M; Lilley, Marvin D; Baross, John A; Summons, Roger E; Sylva, Sean P</p> <p>2005-03-01</p> <p>The serpentinite-hosted Lost City <span class="hlt">hydrothermal</span> field is a remarkable submarine ecosystem in which geological, chemical, and biological processes are intimately interlinked. Reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids, with temperatures ranging from <40 degrees to 90 degrees C at pH 9 to 11, and carbonate chimneys 30 to 60 meters tall. A low diversity of microorganisms related to methane-cycling Archaea thrive in the warm porous interiors of the edifices. Macrofaunal communities show a degree of species diversity at least as high as that of black smoker vent <span class="hlt">sites</span> along the Mid-Atlantic Ridge, but they lack the high biomasses of chemosynthetic organisms that are typical of volcanically driven systems. PMID:15746419</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70177135','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70177135"><span id="translatedtitle">Monitoring the <span class="hlt">hydrothermal</span> system in Long Valley caldera, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Farrar, C.D.; Sorey, M.L.</p> <p>1985-01-01</p> <p>An ongoing program to monitor the <span class="hlt">hydrothermal</span> system in Long Valley for changes caused by volcanic or tectonic processes has produced considerable data on the water chemistry and discharge of springs and fluid temperatures and pressures in wells. Chemical and isotopic data collected under this program have greatly expanded the knowledge of chemical variability both in space and time. Although no chemical or isotopic changes in hot spring waters can be attributed directly to volcanic or tectonic processes, changes in hot spring chemistry that have been recorded probably relate to interactions between and variations in the quantity of liquid and gas discharged. Stable carbon isotope data are consistent with a carbon source either perform the mantle or from metamorphosed carbonate rocks. Continuous and periodic measurements of hot spring discharge at several <span class="hlt">sites</span> show significant co seismic and a seismic changes since 1980.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15746419','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15746419"><span id="translatedtitle">A serpentinite-hosted ecosystem: the Lost City <span class="hlt">hydrothermal</span> field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelley, Deborah S; Karson, Jeffrey A; Früh-Green, Gretchen L; Yoerger, Dana R; Shank, Timothy M; Butterfield, David A; Hayes, John M; Schrenk, Matthew O; Olson, Eric J; Proskurowski, Giora; Jakuba, Mike; Bradley, Al; Larson, Ben; Ludwig, Kristin; Glickson, Deborah; Buckman, Kate; Bradley, Alexander S; Brazelton, William J; Roe, Kevin; Elend, Mitch J; Delacour, Adélie; Bernasconi, Stefano M; Lilley, Marvin D; Baross, John A; Summons, Roger E; Sylva, Sean P</p> <p>2005-03-01</p> <p>The serpentinite-hosted Lost City <span class="hlt">hydrothermal</span> field is a remarkable submarine ecosystem in which geological, chemical, and biological processes are intimately interlinked. Reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids, with temperatures ranging from <40 degrees to 90 degrees C at pH 9 to 11, and carbonate chimneys 30 to 60 meters tall. A low diversity of microorganisms related to methane-cycling Archaea thrive in the warm porous interiors of the edifices. Macrofaunal communities show a degree of species diversity at least as high as that of black smoker vent <span class="hlt">sites</span> along the Mid-Atlantic Ridge, but they lack the high biomasses of chemosynthetic organisms that are typical of volcanically driven systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040065937&hterms=Hydrothermal+vents&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2528Hydrothermal%2Bvents%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040065937&hterms=Hydrothermal+vents&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2528Hydrothermal%2Bvents%2529"><span id="translatedtitle">Optical Detection of Organic Chemical Biosignatures at <span class="hlt">Hydrothermal</span> Vents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Conrad, P. G.; Lane, A. L.; Bhartia, R.; Hug, W. H.</p> <p>2004-01-01</p> <p>We have developed a non-contact, optical life detection instrument that can detect organic chemical biosignatures in a number of different environments, including dry land, shallow aqueous, deep marine or in ice. Hence, the instrument is appropriate as a biosignature survey tool both for Mars exploration or in situ experiments in an ice-covered ocean such as one might wish to explore on Europa. Here, we report the results we obtained on an expedition aboard the Russian oceanographic vessel Akademik Mstislav Keldysh to <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> in the Pacific Ocean using our life detection instrument MCDUVE, a multichannel, deep ultraviolet excitation fluorescence detector. MCDUVE detected organic material distribution on rocks near the vent, as well as direct detection of organisms, both microbial and microscopic. We also were able to detect organic material issuing directly from vent chimneys, measure the organic signature of the water column as we ascended, and passively observe the emission of light directly from some vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://dl.sciencesocieties.org/publications/sssaj/abstracts/0/0/sssaj2013.07.0298','USGSPUBS'); return false;" href="https://dl.sciencesocieties.org/publications/sssaj/abstracts/0/0/sssaj2013.07.0298"><span id="translatedtitle">Soil-plant-microbial relations in <span class="hlt">hydrothermally</span> altered soils of Northern California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Blecker, S.W.; Stillings, L.L.; DeCrappeo, N.M.; Ippolito, J.A.</p> <p>2014-01-01</p> <p>Soils developed on relict <span class="hlt">hydrothermally</span> altered soils throughout the Western USA present unique opportunities to study the role of geology on above and belowground biotic activity and composition. Soil and vegetation samples were taken at three unaltered andesite and three <span class="hlt">hydrothermally</span> altered (acid-sulfate) <span class="hlt">sites</span> located in and around Lassen VolcanicNational Park in northeastern California. In addition, three different types of disturbed areas (clearcut, thinned, and pipeline) were sampled in acid-sulfate altered <span class="hlt">sites</span>. Soils were sampled (0–15 cm) in mid-summer 2010 from both under-canopy and between-canopy areas within each of the <span class="hlt">sites</span>. Soils were analyzed for numerous physical and chemical properties along with soil enzyme assays, C and N mineralization potential, microbial biomass-C and C-substrate utilization. Field vegetation measurements consisted of canopy cover by life form (tree, shrub, forb, and grass), tree and shrub density, and above-ground net primary productivity of the understory. Overall, parameters at the clearcut <span class="hlt">sites</span> were more similar to the unaltered <span class="hlt">sites</span>, while parameters at the thinned and pipeline <span class="hlt">sites</span> were more similar to the altered <span class="hlt">sites</span>. We employed principal components analysis (PCA) to develop two soil quality indices (SQI) to help quantify the differences among the <span class="hlt">sites</span>: one based on the correlation between soil parameters and canopy cover, and the second based on six sub-indices. Soil quality indices developed in these systems could provide a means for monitoring and identifying key relations between the vegetation, soils, and microorganisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatSR...3E3487I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatSR...3E3487I"><span id="translatedtitle">Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan</p> <p>2013-12-01</p> <p>Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> systems have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> systems is scarce in the literature. Here we report of fossilized microorganisms in association with cavity-grown <span class="hlt">hydrothermal</span> minerals from the 458 Ma Lockne impact structure, Sweden. Based on morphological characteristics the fossilized microorganisms are interpreted as fungi. We further infer the kerogenization of the microfossils, and thus the life span of the fungi, to be contemporaneous with the <span class="hlt">hydrothermal</span> activity and migration of hydrocarbons in the system. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> systems associated with impact structures can support colonization by microbial life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864048','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864048"><span id="translatedtitle">Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> system</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan</p> <p>2013-01-01</p> <p>Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> systems have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> systems is scarce in the literature. Here we report of fossilized microorganisms in association with cavity-grown <span class="hlt">hydrothermal</span> minerals from the 458 Ma Lockne impact structure, Sweden. Based on morphological characteristics the fossilized microorganisms are interpreted as fungi. We further infer the kerogenization of the microfossils, and thus the life span of the fungi, to be contemporaneous with the <span class="hlt">hydrothermal</span> activity and migration of hydrocarbons in the system. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> systems associated with impact structures can support colonization by microbial life. PMID:24336641</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24336641','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24336641"><span id="translatedtitle">Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan</p> <p>2013-12-16</p> <p>Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> systems have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> systems is scarce in the literature. Here we report of fossilized microorganisms in association with cavity-grown <span class="hlt">hydrothermal</span> minerals from the 458 Ma Lockne impact structure, Sweden. Based on morphological characteristics the fossilized microorganisms are interpreted as fungi. We further infer the kerogenization of the microfossils, and thus the life span of the fungi, to be contemporaneous with the <span class="hlt">hydrothermal</span> activity and migration of hydrocarbons in the system. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> systems associated with impact structures can support colonization by microbial life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24336641','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24336641"><span id="translatedtitle">Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan</p> <p>2013-01-01</p> <p>Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> systems have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> systems is scarce in the literature. Here we report of fossilized microorganisms in association with cavity-grown <span class="hlt">hydrothermal</span> minerals from the 458 Ma Lockne impact structure, Sweden. Based on morphological characteristics the fossilized microorganisms are interpreted as fungi. We further infer the kerogenization of the microfossils, and thus the life span of the fungi, to be contemporaneous with the <span class="hlt">hydrothermal</span> activity and migration of hydrocarbons in the system. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> systems associated with impact structures can support colonization by microbial life. PMID:24336641</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H51D1223T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H51D1223T"><span id="translatedtitle">Basin scale permeability and thermal evolution of a magmatic <span class="hlt">hydrothermal</span> system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taron, J.; Hickman, S. H.; Ingebritsen, S.; Williams, C.</p> <p>2013-12-01</p> <p>Large-scale <span class="hlt">hydrothermal</span> systems are potentially valuable energy resources and are of general scientific interest due to extreme conditions of stress, temperature, and reactive chemistry that can act to modify crustal rheology and composition. With many proposed <span class="hlt">sites</span> for Enhanced Geothermal Systems (EGS) located on the margins of large-scale <span class="hlt">hydrothermal</span> systems, understanding the temporal evolution of these systems contributes to <span class="hlt">site</span> selection, characterization and design of EGS. This understanding is also needed to address the long-term sustainability of EGS once they are created. Many important insights into heat and mass transfer within natural <span class="hlt">hydrothermal</span> systems can be obtained through <span class="hlt">hydrothermal</span> modeling assuming that stress and permeability structure do not evolve over time. However, this is not fully representative of natural systems, where the effects of thermo-elastic stress changes, chemical fluid-rock interactions, and rock failure on fluid flow and thermal evolution can be significant. The quantitative importance of an evolving permeability field within the overall behavior of a large-scale <span class="hlt">hydrothermal</span> system is somewhat untested, and providing such a parametric understanding is one of the goals of this study. We explore the thermal evolution of a sedimentary basin <span class="hlt">hydrothermal</span> system following the emplacement of a magma body. The Salton Sea geothermal field and its associated magmatic system in southern California is utilized as a general backdrop to define the initial state. Working within the general framework of the open-source scientific computing initiative OpenGeoSys (www.opengeosys.org), we introduce full treatment of thermodynamic properties at the extreme conditions following magma emplacement. This treatment utilizes a combination of standard Galerkin and control-volume finite elements to balance fluid mass, mechanical deformation, and thermal energy with consideration of local thermal non-equilibrium (LTNE) between fluids and solids</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMOS11B1476M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMOS11B1476M"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> regime of the Iheya-North <span class="hlt">hydrothermal</span> field inferred from surface heat flow data and, IODP Expedition 331 drilling results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masaki, Y.; Takai, K.; Mottl, M. J.; Hartnett, H. E.; Kinoshita, M.; IODP Expedition 331 scientists</p> <p>2011-12-01</p> <p>The Okinawa trough is a backarc basin, located between the Ryukyu arc-trench system and the Asian continent. It is considered to be in a rifting stage of the continental lithosphere. The trough contains both hemipelagic and volcanic sediments, and numerous <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> have been discovered inside the trough. Iheya-North <span class="hlt">hydrothermal</span> field is surrounded by the Iheya-North knolls in the middle Okinawa trough. Active chimneys as well as diffuse venting area has been located and studied in detail through various geological and geophysical surveys. To clarify the spatial scale of the <span class="hlt">hydrothermal</span> circulation system, intensive heat flow measurements were carried out and 78 heat flow data were obtained from 2002 to 2008 in and around the knolls. In 2010, drilling study was carried out during the IODP Expedition 331, and new subbottom temperature data were obtained around the <span class="hlt">hydrothermal</span> <span class="hlt">site</span>. Three distinct zones are identified with different heat flow values which we termed the high-heat-flow zone (>1 W/m^2; HHZ), moderate-heat-flow zone (1-0.1 W/m^2; MHZ), and low-heat-flow zone (<0.1 W/m^2) within 3 km from the active <span class="hlt">hydrothermal</span> field. In the HHZ located near the western edge of the basin, extremely high and widely scattered heat flow values were measured within ~500 m of the active <span class="hlt">hydrothermal</span> mounds, venting black smoker fluid of maximum 311 °C. With increasing distance east of the HHZ, heat flow gradually decreases towards MHZ and LHZ. We suggest that such anomalously low heat flow can be explained by the recharge of seawater into the formation, and that <span class="hlt">hydrothermal</span> vents or diffuse flow in the HHZ can dribe this kilometer-scale <span class="hlt">hydrothermal</span> circulation. During IODP Expedition 331, we carried out coring and in-situ temperature measurements in the HHZ and LHZ. We could not obtain enough core (less than 1 % core recovery). In the HHZ, the temperature data showed over 55 °C only few meters below the seafloor. After drilling, the temperature in the bore</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24632409','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24632409"><span id="translatedtitle">Catalytic <span class="hlt">hydrothermal</span> pretreatment of corncob into xylose and furfural via solid acid catalyst.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Huiling; Deng, Aojie; Ren, Junli; Liu, Changyu; Lu, Qi; Zhong, Linjie; Peng, Feng; Sun, Runcang</p> <p>2014-04-01</p> <p>Selectively catalytic <span class="hlt">hydrothermal</span> pretreatment of corncob into xylose and furfural has been developed in this work using solid acid catalyst (SO4(2-)/TiO2-ZrO2/La(3+)). The effects of corncob-to-water ratio, reaction temperature and residence time on the performance of catalytic <span class="hlt">hydrothermal</span> pretreatment were investigated. Results showed that the solid residues contained mainly lignin and cellulose, which was indicative of the efficient removal of hemicelluloses from corncob by <span class="hlt">hydrothermal</span> method. The prepared catalyst with high thermal stability and strong acid <span class="hlt">sites</span> originated from the acid functional groups was confirmed to contribute to the hydrolysis of polysaccharides into monosaccharides followed by dehydration into furfural. Highest furfural yield (6.18 g/100g) could be obtained at 180°C for 120 min with 6.80 g/100g xylose yield when the corncob/water ratio of was 10:100. Therefore, selectively catalytic <span class="hlt">hydrothermal</span> pretreatment of lignocellulosic biomass into important platform chemicals by solid acids is considered to be a potential treatment for biodiesel and chemical production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPS...312..146A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPS...312..146A"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> preparation of fluorinated graphene hydrogel for high-performance supercapacitors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>An, Haoran; Li, Yu; Long, Peng; Gao, Yi; Qin, Chengqun; Cao, Chen; Feng, Yiyu; Feng, Wei</p> <p>2016-04-01</p> <p>Fluorinated graphene hydrogels (FGHs) are synthesized through a one-step <span class="hlt">hydrothermal</span> process and applied as the binder/additive-free electrode materials for supercapacitors. Along with the reduction of graphene oxide (GO), fluorine atoms incorporate into the graphene framework through the substitution process with the residual phenol, ether or carbonyl groups, forming different fluorine species subsequently. The fluorine content and the Csbnd F bond configuration are easily adjusted by the <span class="hlt">hydrothermal</span> temperature. X-ray photo electron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectra indicate the mainly existent of semi-ionic Csbnd F bonds in the prepared FGHs. The semi-ionic Csbnd F bonds in FGHs facilitate the ion transport, enhance the electrical conductivity and provide active <span class="hlt">sites</span> for the faradic reaction. Therefore, the electrochemical performances of FGHs are better than the fluorine-free graphene hydrogel prepared by the same <span class="hlt">hydrothermal</span> process. FGH prepared at the <span class="hlt">hydrothermal</span> temperature of 150 °C exhibit the highest specific capacitance (227 F g-1) and the best rate capability. The corresponding symmetric supercapacitor delivers the power density as high as 50.05 kW kg-1 at the current density of 50 A g-1. These results indicate the FGHs are the ideal electrode materials with the great potential in the field of high-power supercapacitors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3695286','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3695286"><span id="translatedtitle">Characterizing the distribution and rates of microbial sulfate reduction at Middle Valley <span class="hlt">hydrothermal</span> vents</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Frank, Kiana L; Rogers, Daniel R; Olins, Heather C; Vidoudez, Charles; Girguis, Peter R</p> <p>2013-01-01</p> <p>Few studies have directly measured sulfate reduction at <span class="hlt">hydrothermal</span> vents, and relatively little is known about how environmental or ecological factors influence rates of sulfate reduction in vent environments. A better understanding of microbially mediated sulfate reduction in <span class="hlt">hydrothermal</span> vent ecosystems may be achieved by integrating ecological and geochemical data with metabolic rate measurements. Here we present rates of microbially mediated sulfate reduction from three distinct <span class="hlt">hydrothermal</span> vents in the Middle Valley vent field along the Juan de Fuca Ridge, as well as assessments of bacterial and archaeal diversity, estimates of total biomass and the abundance of functional genes related to sulfate reduction, and in situ geochemistry. Maximum rates of sulfate reduction occurred at 90 °C in all three deposits. Pyrosequencing and functional gene abundance data revealed differences in both biomass and community composition among <span class="hlt">sites</span>, including differences in the abundance of known sulfate-reducing bacteria. The abundance of sequences for Thermodesulfovibro-like organisms and higher sulfate reduction rates at elevated temperatures suggests that Thermodesulfovibro-like organisms may have a role in sulfate reduction in warmer environments. The rates of sulfate reduction presented here suggest that—within anaerobic niches of <span class="hlt">hydrothermal</span> deposits—heterotrophic sulfate reduction may be quite common and might contribute substantially to secondary productivity, underscoring the potential role of this process in both sulfur and carbon cycling at vents. PMID:23535916</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6214526','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6214526"><span id="translatedtitle">Microearthquakes in the black smoker <span class="hlt">hydrothermal</span> field, East Pacific Rise at 21/sup 0/N</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Riedesel, M.; Orcutt, J.A.; MacDonald, K.C.; McClain, J.S.</p> <p>1982-12-10</p> <p>In July and August 1980, an array of five ocean bottom seismographs was deployed within 3 km of the 350 /sup 0/C <span class="hlt">hydrothermal</span> vents at the Rivera submersible experiment (RISE) <span class="hlt">site</span> at 21/sup 0/N, on the East Pacific Rise. Two of these instruments were placed within 600 m of the vents, using a transponder navigation network. The array detected four basic types of events. The first type consisted of local, very small microearthquakes. Locations obtained for 11 of these events place three within 1 km of the vents, with the others elsewhere along the rise crest. They appear to originate either from movement on the faults in the area or from the <span class="hlt">hydrothermal</span> system beneath this area. A study of the S-P times of this type indicates a maximum hypocentral depth of 2-3 km, implying a similar limit to the depth of <span class="hlt">hydrothermal</span> circulation and brittle fracturing in the vicinity of the vents. The second type of event found consisted of emergent earthquakes that have many of the characteristics of volcanic harmonic tremor. The frequency of these events falls in the 1-5 Hz range and are similar in appearance to those seen at Mount St. Helens prior to and during its May 1980 eruption. They may be either <span class="hlt">hydrothermal</span> or volcanic in origin. The third type of event produced a very monochromatic, high-frequency seismogram, with the energy concentrated at 20 Hz. These events also appear to have a local origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23535916','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23535916"><span id="translatedtitle">Characterizing the distribution and rates of microbial sulfate reduction at Middle Valley <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Frank, Kiana L; Rogers, Daniel R; Olins, Heather C; Vidoudez, Charles; Girguis, Peter R</p> <p>2013-07-01</p> <p>Few studies have directly measured sulfate reduction at <span class="hlt">hydrothermal</span> vents, and relatively little is known about how environmental or ecological factors influence rates of sulfate reduction in vent environments. A better understanding of microbially mediated sulfate reduction in <span class="hlt">hydrothermal</span> vent ecosystems may be achieved by integrating ecological and geochemical data with metabolic rate measurements. Here we present rates of microbially mediated sulfate reduction from three distinct <span class="hlt">hydrothermal</span> vents in the Middle Valley vent field along the Juan de Fuca Ridge, as well as assessments of bacterial and archaeal diversity, estimates of total biomass and the abundance of functional genes related to sulfate reduction, and in situ geochemistry. Maximum rates of sulfate reduction occurred at 90 °C in all three deposits. Pyrosequencing and functional gene abundance data revealed differences in both biomass and community composition among <span class="hlt">sites</span>, including differences in the abundance of known sulfate-reducing bacteria. The abundance of sequences for Thermodesulfovibro-like organisms and higher sulfate reduction rates at elevated temperatures suggests that Thermodesulfovibro-like organisms may have a role in sulfate reduction in warmer environments. The rates of sulfate reduction presented here suggest that--within anaerobic niches of <span class="hlt">hydrothermal</span> deposits--heterotrophic sulfate reduction may be quite common and might contribute substantially to secondary productivity, underscoring the potential role of this process in both sulfur and carbon cycling at vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B13C0630H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B13C0630H"><span id="translatedtitle">Community Structure Comparisons of <span class="hlt">Hydrothermal</span> Vent Microbial Mats Along the Mariana Arc and Back-arc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hager, K. W.; Fullerton, H.; Moyer, C. L.</p> <p>2015-12-01</p> <p><span class="hlt">Hydrothermal</span> vents along the Mariana Arc and back-arc represent a hotspot of microbial diversity that has not yet been fully recognized. The Mariana Arc and back-arc contain <span class="hlt">hydrothermal</span> vents with varied vent effluent chemistry and temperature, which translates to diverse community composition. We have focused on iron-rich <span class="hlt">sites</span> where the dominant primary producers are iron oxidizing bacteria. Because microbes from these environments have proven elusive in culturing efforts, we performed culture independent analysis among different microbial communities found at these <span class="hlt">hydrothermal</span> vents. Terminal-restriction fragment length polymorphism (T-RFLP) and Illumina sequencing of small subunit ribosomal gene amplicons were used to characterize community members and identify samples for shotgun metagenomics. Used in combination, these methods will better elucidate the composition and characteristics of the bacterial communities at these <span class="hlt">hydrothermal</span> vent systems. The overarching goal of this study is to evaluate and compare taxonomic and metabolic diversity among different communities of microbial mats. We compared communities collected on a fine scale to analyze the bacterial community based on gross mat morphology, geography, and nearby vent effluent chemistry. Taxa richness and evenness are compared with rarefaction curves to visualize diversity. As well as providing a survey of diversity this study also presents a juxtaposition of three methods in which ribosomal small subunit diversity is compared with T-RFLP, next generation amplicon sequencing, and metagenomic shotgun sequencing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS42A..06G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS42A..06G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Exploration of Mid-Ocean Ridges: Where Might the Largest Sulfide Deposits Occur?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>German, C. R.; Petersen, S.; Hannington, M. D.</p> <p>2015-12-01</p> <p>We review the distribution of modern-day seafloor <span class="hlt">hydrothermal</span> activity along the global mid-ocean ridge crest (MOR) and the mineral deposits being formed at those <span class="hlt">sites</span>. To date, one form of <span class="hlt">hydrothermal</span> activity - "black smoker" venting - has been prospected for along >30% of the global mid ocean ridge crest and some important trends have emerged. Submarine venting can occur along all mid-ocean ridges, of all spreading rates, in all ocean basins. While the abundance of currently active venting (from water column signals), scales linearly with seafloor spreading rate (a proxy for magmatic heat-flux) there is an "excess" of high temperature venting along slow and ultra-slow spreading ridges when compared to early predictions. Consistent with this, no more than half of the <span class="hlt">sites</span> responsible for "black smoker" plume signals along the slow spreading Mid Atlantic Ridge are associated with magmatic systems with the other half hosted under tectonic control. The latter appear both to be longer-lived than, and to give rise to much larger sulfide deposits than, their magmatic counterparts - presumably as a result of sustained fluid flow. Where these tectonic-hosted systems also involve water-rock interaction with ultramafic sources, seafloor massive sulfide deposits exhibit highly concentrated Cu and Au in surface samples (>10wt.% average Cu content and >3ppm average Au). Intriguingly, first detailed examinations of <span class="hlt">hydrothermally</span> active <span class="hlt">sites</span> along ultraslow-spreading ridges seems to indicate that they may depart beyond the slow-spreading Mid-Atlantic Ridge pattern. <span class="hlt">Hydrothermal</span> plume distributions may follow the same (~50:50) distribution of "black smoker" plume signals between magmatic and tectonics settings, but the first three "black smoker" <span class="hlt">sites</span> tracked to source have all revealed large polymetallic sulfide deposits - in both magmatic as well as tectonic settings. Could ultra-slow ridges represent the richest mineral resource potential along the global MOR?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B43A0898F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B43A0898F"><span id="translatedtitle">Environmental controls on methanogen viability in the <span class="hlt">hydrothermal</span> waters of the El Tatio geyser field, Chile.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franks, M. A.; Bennett, P. C.; Omelon, C.; Engel, A. S.</p> <p>2007-12-01</p> <p>At the El Tatio geyser field, a unique <span class="hlt">hydrothermal</span> <span class="hlt">site</span> located in the Andes Mountains in Chile, methanogenic archaea were found in only two of the hundreds of <span class="hlt">hydrothermal</span> features. Reported here is an investigation into the environmental and geochemical controls on the distribution of methanogenic archaea. Located in the hyper- arid Atacama Desert, El Tatio waters are characterized by high salinity (95-175mM), Na-Cl type waters and circum-neutral pH (6.5-7), with very low inorganic carbon (0.1-0.5 mM TIC), but very high concentrations of As and Sb (300-700 uM As, 10-30uM Sb). Extensive bacterial mats thrive in most of the shallow run-off streams originating from <span class="hlt">hydrothermal</span> features. In order to determine geochemical controls on methanogen populations, major and trace elements, including As and Sb speciation and concentrations, were determined using IC and HPLC-ICP-MS methods. The structure of microbial communities was analyzed using MPN enumeration of methanogens, culturing, and phylogenetic analysis using molecular techniques. Here, as in many <span class="hlt">hydrothermal</span> regions, temperature and geochemical gradients influence the microbial ecology. Results from MPN enumeration indicate methanogen populations are dominated by H2-utilizing (carbonate reducing) archaea at both of the <span class="hlt">sites</span>, with some acetate-oxidizing archaea present. These <span class="hlt">sites</span> contain comparatively high DIC concentrations; however, it is unclear whether this is a control or a product of methanogenic archaea. Water quality analyses also show a strong correlation between antimony concentrations and the presence of methanogens; methanogenic archaea being present only at <span class="hlt">sites</span> with 17 uM Sb concentrations or less.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SciDr..13...19T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SciDr..13...19T"><span id="translatedtitle">IODP Expedition 331: Strong and Expansive Subseafloor <span class="hlt">Hydrothermal</span> Activities in the Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takai, K.; Mottl, M. J.; Nielsen, S. H. H.; IODP Expedition 331 Scientists, the</p> <p>2012-04-01</p> <p>Integrated Ocean Drilling Program (IODP) Expedition 331 drilled into the Iheya North <span class="hlt">hydrothermal</span> system in the middle Okinawa Trough in order to investigate active subseafloor microbial ecosystems and their physical and chemical settings. We drilled five <span class="hlt">sites</span> during Expedition 331 using special guide bases at three holes for reentry, casing, and capping, including installation of a steel mesh platform with valve controls for postcruise sampling of fluids. At <span class="hlt">Site</span> C0016, drilling at the base of the North Big Chimney (NBC) mound yielded low recovery, but core included the first Kuroko-type black ore ever recovered from the modern subseafloor. The other four <span class="hlt">sites</span> yielded interbedded hemipelagic and strongly pumiceous volcaniclastic sediment, along with volcanogenic breccias that are variably <span class="hlt">hydrothermally</span> altered and mineralized. At most <span class="hlt">sites</span>, analyses of interstitial water and headspace gas yielded complex patterns with depth and lateral distance of only a few meters. Documented processes included formation of brines and vapor-rich fluids by phase separation and segregation, uptake of Mg and Na by alteration minerals in exchange for Ca, leaching of K at high temperature and uptake at low temperature, anhydrite precipitation, potential microbial oxidation of organic matter and anaerobic oxidation of methane utilizing sulfate, and methanogenesis. Shipboard analyses have found evidence for microbial activity in sediments within the upper 10-30 m below seafloor (mbsf) where temperatures were relatively low, but little evidence in the deeper <span class="hlt">hydrothermally</span> altered zones and <span class="hlt">hydrothermal</span> fluid regime. doi:<a href="http://dx.doi.org/10.2204/iodp.sd.13.03.2011" target="_blank">10.2204/iodp.sd.13.03.2011</a></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7049404','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7049404"><span id="translatedtitle">Deep sea <span class="hlt">hydrothermal</span> vents. (Latest citations from Oceanic abstracts). Published Search</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1994-04-01</p> <p>The bibliography contains citations concerning biological, chemical, and geophysical investigations of seafloor <span class="hlt">hydrothermal</span> vents. Biological community descriptions, primary production and growth studies, the nature and occurrence of mineral deposits, and the structure and morphology of vent systems are among the topics discussed. Specific <span class="hlt">site</span> studies, and general investigations are considered. (Contains a minimum of 157 citations and includes a subject term index and title list.)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1061T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1061T"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Activity on ultraslow Spreading Ridge: new <span class="hlt">hydrothermal</span> fields found on the Southwest Indian ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tao, C.; Li, H.; Deng, X.; Lei, J.; Wang, Y.; Zhang, K.; Zhou, J.; Liu, W.</p> <p>2014-12-01</p> <p>Ultraslow spreading ridge makes up about 25% of global mid-ocean ridge length. Previous studies believed that <span class="hlt">hydrothermal</span> activity is not widespread on the ultraslow spreading ridge owing to lower magma supply. Southwest Indian ridge (SWIR) with the spreading rate between 1.2cm/a to 1.4cm/a, represents the ultraslow spreading ridge. In 2007, Chinese Cruise (CC) 19th discovered the Dragon Flag deposit (DFD) on the SWIR, which is the first active <span class="hlt">hydrothermal</span> field found on the ultraslow spreading ridge. In recent years, over 10 <span class="hlt">hydrothermal</span> fields have been found on the SWIR between Indomed and Gallieni transform faults by the Chinese team. Tao et al. (2012) implied that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for <span class="hlt">hydrothermal</span> activities. In 2014, CC 30thdiscovered five <span class="hlt">hydrothermal</span> fields and several <span class="hlt">hydrothermal</span> anomalies on the SWIR. Dragon Horn Area (DHA). The DHA is located on the southern of segment 27 SWIR, with an area of about 400 km2. The geophysical studies indicated that the DHA belongs to the oceanic core complex (OCC), which is widespread on the slow spreading ridges (Zhao et al., 2013). The rocks, such as gabbro, serpentinized peridotite, and consolidated carbonate were collected in the DHA, which provide the direct evidence with the existence of the OCC. However, all rock samples gathered by three TV-grab stations are basalts on the top of the OCC. A <span class="hlt">hydrothermal</span> anomaly area, centered at 49.66°E,37.80° S with a range of several kms, is detected in the DHA. It is probably comprised of several <span class="hlt">hydrothermal</span> fields and controlled by a NW fault. New discovery of <span class="hlt">hydrothermal</span> fields. From January to April 2014, five <span class="hlt">hydrothermal</span> fields were discovered on the SWIR between 48°E to 50°E during the leg 2&3 of the CC 30th, which are the Su Causeway field (48.6°E, 38.1°S), Bai Causeway field (48.8°E, 37.9 °S), Dragon</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814058D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814058D"><span id="translatedtitle">Dynamic typology of <span class="hlt">hydrothermal</span> systems: competing effects of advection, dispersion and reactivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dolejs, David</p> <p>2016-04-01</p> <p>Genetic interpretation <span class="hlt">hydrothermal</span> systems relies on recognition of (i) <span class="hlt">hydrothermal</span> fluid source, (ii) fluid migration pathways, and (iii) deposition <span class="hlt">site</span> identified by <span class="hlt">hydrothermal</span> alteration and/or mineralization. Frequently, only the last object is of interest or accessible to direct observation, but constraints on the fluid source (volume) and pathways can be obtained from evaluation of the time-integrated fluid flux during <span class="hlt">hydrothermal</span> event. Successful interpretation of the petrological record, that is, progress of alteration reactions, relies on identification of individual contributions arising from solute advection (to the deposition <span class="hlt">site</span>), its lateral dispersion, and reaction efficiency. Although these terms are all applicable in a mass-conservation relationship within the framework of the transport theory, they are rarely considered simultaneously and their relative magnitudes evaluated. These phenomena operate on variable length and time scales, and may in turn provide insight into the system dynamics such as flow, diffusion and reaction rates, or continuous vs. episodic behavior of <span class="hlt">hydrothermal</span> events. In addition, here we demonstrate that they also affect estimate of the net fluid flux, frequently by several orders of magnitude. The extent of alteration and mineralization reactions between the <span class="hlt">hydrothermal</span> fluid and the host environment is determined by: (i) temperature, pressure or any other gradients across the mineralization <span class="hlt">site</span>, (ii) magnitude of disequilibrium at inflow to the mineralization <span class="hlt">site</span>, which is related to physico-chemical gradient between the fluid source and the mineralization <span class="hlt">site</span>, and (iii) chemical redistribution (dispersion) within the mineralization <span class="hlt">site</span>. We introduce quantitative mass-transport descriptors - Péclet and Damköhler II numbers - to introduce division into dispersion-dominated, advection-dominated and reaction-constrained systems. Dispersive systems are characterized by lateral solute redistribution, driven by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986GeCoA..50.2615M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986GeCoA..50.2615M"><span id="translatedtitle">Marcasite precipitation from <span class="hlt">hydrothermal</span> solutions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murowchick, James B.; Barnes, H. L.</p> <p>1986-12-01</p> <p>Pyrite and marcasite were precipitated by both slow addition of aqueous Fe2+ and SiO32- to an H2S solution and by mixing aqueous Fe2+ and Na2S4 solutions at 75°C. H2S2 or HS2- and H2S4 or HS4- were formed in the S2O32- and Na2S4 experiments, respectively. Marcasite formed at pH < pK1 of the polysulfide species present (for H2S2, pK1 = 5.0; for H2S4, pK1 = 3.8 at 25°C). Marcasite forms when the neutral sulfane is the dominant polysulfide, whereas pyrite forms when mono-or divalent polysulfides are dominant. In natural solutions where H2S2 and HS2 are likely to be the dominant polysulfides, marcasite will form only below pH 5 at all temperatures. The pH-dependent precipitation of pyrite and marcasite may be caused by electrostatic interactions between polysulfide species and pyrite or marcasite growth surfaces: the protonated ends of H2S2 and HS2 are repelled from pyrite growth <span class="hlt">sites</span> but not from marcasite growth <span class="hlt">sites</span>. The negative ions HS2 and S22- are strongly attracted to the positive pyrite growth <span class="hlt">sites</span>. Masking of 1πg* electrons in the S2 group by the protons makes HS2 and H2S2 isoelectronic with AsS2- and As22-, respectively (TOSSELLet al., 1981). Thus, the loellingitederivative structure (marcasite) results when both ends of the polysulfide are protonated. Marcasite occurs abundantly only for conditions below pH 5 and where H2S2 was formed near the <span class="hlt">site</span> of deposition by either partial oxidation of aqueous H2S by O2 or by the reaction of higher oxidation state sulfur species that are reactive with H2S at the conditions of formation e.g., S2O32- but not SO42-. The temperature of formation of natural marcasite may be as high as 240°C (HANNINGTON and SCOTT, 1985), but preservation on a multimillion-year scale seems to require post-depositional temperatures of below about 160°C (RISING, 1973; MCKIBBEN and ELDERS, 1985).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/264487','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/264487"><span id="translatedtitle">Natural occurrence and stability of pyrochlore in carbonatites, related <span class="hlt">hydrothermal</span> systems, and weathering environments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lumpkin, G.R.; Mariano, A.N.</p> <p>1996-08-01</p> <p>Stoichiometric and non-stoichiometric (defect) pyrochlores crystallize during the magmatic and late magmatic-<span class="hlt">hydrothermal</span> phases of carbonatite emplacement (T > 450--550 C, P < 2 kb). Defect pyrochlores can also form at low temperatures in laterite horizons during weathering. After crystallization, pyrochlore is subject to alteration by <span class="hlt">hydrothermal</span> fluids (T {approximately} 550--200 C) and ground water. Alteration occurs primarily by ion exchange of low valence A-<span class="hlt">site</span> cations together with O, F, and OH ions. The high valence cations Th and U are generally immobile; however, the authors have documented one example of <span class="hlt">hydrothermal</span> alteration involving loss of U together with cation exchange at the B-<span class="hlt">site</span> in samples from Mountain Pass, California. During laterite accumulation, the cation exchange rate of pyrochlore greatly exceeds the rate of matrix dissolution. The exceptional durability of pyrochlore in natural environments is related to the stability of the B-<span class="hlt">site</span> framework cations. In carbonatites, defect pyrochlores may contain significant amounts of Si (up to 7.6 wt% SiO{sub 2}) which is negatively correlated with Nb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27076100','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27076100"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of bi-functional nanostructured manganese tungstate catalysts for selective oxidation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Xuan; Lunkenbein, Thomas; Kröhnert, Jutta; Pfeifer, Verena; Girgsdies, Frank; Rosowski, Frank; Schlögl, Robert; Trunschke, Annette</p> <p>2016-07-01</p> <p>The mechanism of C-H activation in selective oxidation reactions of short-chain alkane molecules over transition metal oxides is critically affected by the balance of acid-base and redox <span class="hlt">sites</span> at the surface of the catalyst. Using the example of manganese tungstate we discuss how the relative abundance of these <span class="hlt">sites</span> can be controlled via synthetic techniques. Phase-pure catalysts composed of the thermodynamic stable monoclinic MnWO4 phase have been prepared using <span class="hlt">hydrothermal</span> synthesis. Variation of the initial pH value resulted in rod-shaped nano-crystalline MnWO4 catalysts composed of particles with varying aspect ratio. The synthesis products have been analysed using transmission electron microscopy, X-ray diffraction, infrared, and photoelectron spectroscopy. In situ Raman spectroscopy was used to investigate the dissolution-re-crystallization processes occurring under <span class="hlt">hydrothermal</span> conditions. Ethanol oxidation was applied to probe the surface functionalities in terms of acid-base and redox properties. Changes in the aspect ratio of the primary catalyst particles are reflected in the product distribution induced by altering the fraction of acid-base and redox <span class="hlt">sites</span> exposed at the surface of the catalysts in agreement with the proposed mechanism of particle growth by re-crystallization during ageing under <span class="hlt">hydrothermal</span> conditions. PMID:27076100</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMNS33A..02N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMNS33A..02N"><span id="translatedtitle">Evidence for <span class="hlt">Hydrothermal</span> Vents as "Biogeobatteries" (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nielsen, M. E.; Girguis, P. R.</p> <p>2010-12-01</p> <p><span class="hlt">Hydrothermal</span> vents are unique systems that play an important role in oceanic biogeochemical cycles. As chemically reduced <span class="hlt">hydrothermal</span> fluid mixes with cold oxic seawater, minerals precipitate out of solution resulting in chimney structures composed largely of metal sulfides and anhydrite. Pyrite, which is a natural semi-conductor, is the primary sulfide mineral, but other minerals within chimneys are also conductive (e.g. chalcopyrite, wurtzite, and some iron oxides). Sulfide chimneys are also known to host an extensive endolithic microbial community. Accordingly, submarine <span class="hlt">hydrothermal</span> systems appear to be examples of biogeobatteries, wherein conductive mineral assemblages span naturally occuring redox gradients and enable anaerobic microbes to access oxygen as an oxidant via extracellular electron transfer (or EET). To test this hypothesis, we ran a series of electrochemical laboratory experiments in which pyrite was used as an anode (in a vessel flushed with <span class="hlt">hydrothermal</span>-like fluid). When placed in continuity with a carbon fiber cathode, pyrite was found to accept and conduct electrons from both abiotic and biological processes (microbial EET). Specifically, electrical current increased 4-fold (5 nA/m2 to 20 nA/m2) in response to inoculation with a slurry prepared from a <span class="hlt">hydrothermal</span> vent sample. Inspection of the pyrite anode with SEM revealed ubiquitous coverage by microbes. DNA was extracted from the anodes and the inoculum, and was subjected to pyrosequencing to examine prokaryotic diversity. These data suggest that key microbial phylotypes were enriched upon the pyrite, implicating them in EET. In addition, we deployed an in situ experiment based on microbial fuel cell architecture with a graphite anode inserted into a vent wall coupled to a carbon fiber cathode outside the vent. We observed current production over the course of one year, implying microbial EET in situ. Via pyrosequencing, we observed that the microbial community on the anode was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13A1713N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1713N"><span id="translatedtitle">Evaluation of nutrient sources for the sponges inhabited around seafloor <span class="hlt">hydrothermal</span> fields in the Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagashio, H.; Yamanaka, T.; Watanabe, H.; Yamagami, S.; Ise, Y.; Makita, H.</p> <p>2012-12-01</p> <p>Since discovery of seafloor <span class="hlt">hydrothermal</span> vents, the dense and endemic animal communities inhabited around the hot vents have been the most impressive feature for many scientists. Such animals have been known as chemosynthesis-based species and studied many investigators. On the other hand, some benthic animals found on abyssal plain have been observed slightly high density at the adjacent area to active vent <span class="hlt">sites</span>. It implies that those opportunistic benthoses may also rely on the chemosynthetic primary production and the <span class="hlt">hydrothermal</span> chemosynthetic ecosystem may extend widely rather than previous expectation. In that case, it is an interesting issue how the dense sponge community is sustained around the <span class="hlt">hydrothermal</span> fields. For clarifying the issue isotope geochemical study has been performed to evaluate food sources of the sponges and some other animals obtained from the deep seafloor in the Okinawa Trough. Stable isotope analysis for carbon, nitrogen, and sulfur of the sample organisms obtained from the Izena Hole, where active <span class="hlt">hydrothermal</span> emission has been observed, show significant low d13C and d34S values for the sponge samples. Those results suggest plausible contribution of sulfur oxidizing bacteria as food source for the sponges because such low d13C and d34S values are often observed for thioautotrophic chemosynthesis-based animals. The sulfur isotopic ratios of the sponges are almost comparable with the ratio reported hydrogen sulfide emitted from the vents, implying that the source of sulfur for sulfur oxidizing bacteria is magmatic and/or <span class="hlt">hydrothermal</span> in origin. On the other hand, the sponge sample obtained from the Tarama Knoll ,where active <span class="hlt">hydrothermal</span> emission were not found yet, shows similar isotopic characteristics observed for the sponges from the Izena Hole. It may also imply the importance of sulfur oxidizing bacteria as food source for the sponge at the Tarama Knoll. Turbid water was often observed during dive studies by the ROV around the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFMOS11A0338B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFMOS11A0338B"><span id="translatedtitle">The Third Dimension of an Active Back-arc <span class="hlt">Hydrothermal</span> System: ODP Leg 193 at PACMANUS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Binns, R.; Barriga, F.; Miller, D.</p> <p>2001-12-01</p> <p>This first sub-seafloor examination of an active <span class="hlt">hydrothermal</span> system hosted by felsic volcanics, at a convergent margin, obtained drill core from a high-T "smoker" <span class="hlt">site</span> (penetrated to sim200 mbsf) and a low-T <span class="hlt">site</span> of diffuse venting (~400mbsf). We aimed to delineate the lateral and vertical variability in mineralisation and alteration patterns, so as to understand links between volcanological, structural and <span class="hlt">hydrothermal</span> phenomena and the sources of fluids, and to establish the nature and extent of microbial activity within the system. Technological breakthroughs included deployment of a new hard-rock re-entry system, and direct comparison in a hardrock environment of structural images obtained by wireline methods and logging-while-drilling. The PACMANUS <span class="hlt">hydrothermal</span> <span class="hlt">site</span>, at the 1700m-deep crest of a 500m-high layered sequence of dacitic lavas, is notable for baritic massive sulfide chimneys rich in Cu, Zn, Au and Ag. Below an extensive cap 5-40m thick of fresh dacite-rhyodacite, we found unexpectedly pervasive <span class="hlt">hydrothermal</span> alteration of vesicular and flow-banded precursors, accompanied by variably intense fracturing and anhydrite-pyrite veining. Within what appears one major <span class="hlt">hydrothermal</span> event affecting the entire drilled sequence, there is much overprinting and repetition of distinctly allochemical argillaceous (illite-chlorite), acid-sulfate (pyrophyllite-anhydrite) and siliceous assemblages. The alteration profiles include a transition from metastable cristobalite to quartz at depth, and are similar under low-T and high-T vent <span class="hlt">sites</span> but are vertically condensed in a manner suggesting higher thermal gradients beneath the latter. The altered rocks are surprisingly porous (average 25%). Retention of intergranular pore spaces and open vesicles at depth implies elevated <span class="hlt">hydrothermal</span> pressures, whereas evidence from fluid inclusions and <span class="hlt">hydrothermal</span> brecciation denotes local or sporadic phase separation. A maximum measured temperature of 313 degC measured 8 days</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......174G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......174G"><span id="translatedtitle">The formation, oxidation and distribution of pyrite nanoparticles emitted from <span class="hlt">hydrothermal</span> vents: A laboratory and field based approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gartman, Amy</p> <p></p> <p>Recent research identified the presence of nanoparticulate pyrite in <span class="hlt">hydrothermal</span> vent black smoker emissions, and suggested that these nanoparticles may be a transport pathway for iron from <span class="hlt">hydrothermal</span> vents to the larger ocean basin. Here, nanoparticulate pyrite was synthesized via a <span class="hlt">hydrothermal</span> method and oxidized in air- saturated seawater, in order to explore how <span class="hlt">hydrothermally</span> emitted pyrite forms, and may behave in oxic seawater. Additionally, <span class="hlt">hydrothermal</span> emissions from the Mid- Atlantic Ridge were investigated for iron and sulfide speciation and reactions relating to pyrite formation. Pyrite was synthesized via both the Fe(II) + S(0) and the FeS + H 2S pathways of pyrite formation, and factors including surfactant and synthesis time were varied in order to modify morphology. The FeS + H 2S formation pathway, which is likely the pathway of pyrite formation occurring at <span class="hlt">hydrothermal</span> <span class="hlt">sites</span>, reproduces the pyrite nano and sub- micron particles found in black smoker emissions most closely. The oxidation of these pyrite particles results in an initial oxidation rate that is first order with respect to both the pyrite and oxygen concentration in seawater. This work is unique to previous studies on pyrite oxidation in that it uses synthesized, rather than ground and sieved pyrite, and uses seawater as the medium of oxidation. Along with the rate data, this study also demonstrates that the initial oxide formed from pyrite oxidation under these conditions is poorly crystalline and contains Fe(II) and Fe(III). Pyrite nanoparticles were identified at each of the three <span class="hlt">sites</span> investigated at the Mid-Atlantic Ridge (Rainbow, TAG and Snakepit), and their presence at these <span class="hlt">sites</span>, when combined with previous data from Lau Basin and EPR 9 °N demonstrates that they are likely to be a ubiquitous component of black- smoker <span class="hlt">hydrothermal</span> emissions. The Rainbow <span class="hlt">site</span> exhibited the highest concentration of nanoparticulate pyrite measured anywhere to date (1.15 mM). The potential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.V21D0751S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V21D0751S"><span id="translatedtitle">Removal of trace elements in <span class="hlt">hydrothermal</span> plume at submarine volcanic arc <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shitashima, K.</p> <p>2007-12-01</p> <p>On the study of geochemical fluxes of trace elements from the <span class="hlt">hydrothermal</span> system, it is necessary to collect not only samples by the hydro-cast from surface ship and fluid samples using a submersible but also temporally and spatially continuous samples ranging from a fluid to a <span class="hlt">hydrothermal</span> plume. For that purpose, the sampling method along the diluting and rising plume just after erupting from a <span class="hlt">hydrothermal</span> vent is effective. The mini CTDT-RMS was installed onto the submersible. The <span class="hlt">hydrothermal</span> plume samples were collected with monitoring the anomalies of temperature and turbidity by taking the distance from the <span class="hlt">hydrothermal</span> vent gradually. Unfiltered sample for total (particulate + dissolved) trace element concentration and filtered sample for dissolved trace element concentration were analyzed on land. In V, Ni, Cu, Mo, Cd, Pb and Zn, particulate form was predominant in the fluid. The elements that are easy to form a sulfide such as Cu, Cd and Pb were removed as a sulfide precipitate from the fluid before erupting to the deep ocean. Therefore, the concentration of these trace elements in the <span class="hlt">hydrothermal</span> plume showed superiority of a dissolved form, and was slightly high or same concentration in the deep ocean. The concentration of Fe in the fluid was extremely higher (500 - 100,000 times) than that in the deep ocean, and showed a fifty-fifty partition between dissolved form and particulate form. In the <span class="hlt">hydrothermal</span> plume, Fe formed hydroxide mainly and was removed gradually from the plume as a particulate form in dilution and diffusion process of the plume. These hydroxides may play a role of the precipitant that coprecipitate with absorbing the other trace elements. Because Mn is hard to deposit as a sulfide, dissolved form was predominant in the fluid and Mn showed extreme high concentration same as Fe. Mn was discharged to the deep ocean as a dissolved form and removed from the plume as an oxide with increasing the particulate form gradually in dilution</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22431990','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22431990"><span id="translatedtitle">Discovery of new <span class="hlt">hydrothermal</span> activity and chemosynthetic fauna on the Central Indian Ridge at 18°-20° S.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakamura, Kentaro; Watanabe, Hiromi; Miyazaki, Junichi; Takai, Ken; Kawagucci, Shinsuke; Noguchi, Takuro; Nemoto, Suguru; Watsuji, Tomo-o; Matsuzaki, Takuya; Shibuya, Takazo; Okamura, Kei; Mochizuki, Masashi; Orihashi, Yuji; Ura, Tamaki; Asada, Akira; Marie, Daniel; Koonjul, Meera; Singh, Manvendra; Beedessee, Girish; Bhikajee, Mitrasen; Tamaki, Kensaku</p> <p>2012-01-01</p> <p>Indian Ocean <span class="hlt">hydrothermal</span> vents are believed to represent a novel biogeographic province, and are host to many novel genera and families of animals, potentially indigenous to Indian Ocean <span class="hlt">hydrothermal</span> systems. In particular, since its discovery in 2001, much attention has been paid to a so-called 'scaly-foot' gastropod because of its unique iron-sulfide-coated dermal sclerites and the chemosynthetic symbioses in its various tissues. Despite increasing interest in the faunal assemblages at Indian Ocean <span class="hlt">hydrothermal</span> vents, only two <span class="hlt">hydrothermal</span> vent fields have been investigated in the Indian Ocean. Here we report two newly discovered <span class="hlt">hydrothermal</span> vent fields, the Dodo and Solitaire fields, which are located in the Central Indian Ridge (CIR) segments 16 and 15, respectively. Chemosynthetic faunal communities at the Dodo field are emaciated in size and composition. In contrast, at the Solitaire field, we observed faunal communities that potentially contained almost all genera found at CIR <span class="hlt">hydrothermal</span> environments to date, and even identified previously unreported taxa. Moreover, a new morphotype of 'scaly-foot' gastropod has been found at the Solitaire field. The newly discovered 'scaly-foot' gastropod has similar morphological and anatomical features to the previously reported type that inhabits the Kairei field, and both types of 'scaly-foot' gastropods genetically belong to the same species according to analyses of their COI gene and nuclear SSU rRNA gene sequences. However, the new morphotype completely lacks an iron-sulfide coating on the sclerites, which had been believed to be a novel feature restricted to 'scaly-foot' gastropods. Our new findings at the two newly discovered <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> provide important insights into the biodiversity and biogeography of vent-endemic ecosystems in the Indian Ocean. PMID:22431990</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/870475','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/870475"><span id="translatedtitle">Iridium material for <span class="hlt">hydrothermal</span> oxidation environments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hong, Glenn T.; Zilberstein, Vladimir A.</p> <p>1996-01-01</p> <p>A process for <span class="hlt">hydrothermal</span> oxidation of combustible materials in which, during at least a part of the oxidation, corrosive material is present and makes contact with at least a portion of the apparatus over a contact area on the apparatus. At least a portion of the contact surface area comprises iridium, iridium oxide, an iridium alloy, or a base metal overlaid with an iridium coating. Iridium has been found to be highly resistant to environments encountered in the process of <span class="hlt">hydrothermal</span> oxidation. Such environments typically contain greater than 50 mole percent water, together with oxygen, carbon dioxide, and a wide range of acids, bases and salts. Pressures are typically about 27.5 to about 1000 bar while temperatures range as high as 800.degree. C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6440773','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6440773"><span id="translatedtitle">Colorado's <span class="hlt">hydrothermal</span> resource base: an assessment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pearl, R.H.</p> <p>1981-01-01</p> <p>As part of its effort to more accurately describe the nations geothrmal resource potential, the US Department of Energy/Division of Geothermal Energy contracted with the Colorado Geological survey to appraise the <span class="hlt">hydrothermal</span> (hot water) geothermal resources of Colorado. Part of this effort required that the amount of energy that could possibly be contained in the various <span class="hlt">hydrothermal</span> systems in Colorado be estimated. The findings of that assessment are presented. To make these estimates the geothermometer reservoir temperatures estimated by Barrett and Pearl (1978) were used. In addition, the possible reservoir size and extent were estimated and used. This assessment shows that the total energy content of the thermal systems in Colorado could range from 4.872 x 10{sup 15} BTU's to 13.2386 x 10{sup 15} BTU's.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1073584','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1073584"><span id="translatedtitle">Whole Algae <span class="hlt">Hydrothermal</span> Liquefaction Technology Pathway</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Biddy, Mary J.; Davis, Ryan; Jones, Susanne B.; Zhu, Yunhua</p> <p>2013-03-31</p> <p>In support of the Bioenergy Technologies Office, the National Renewable Energy Laboratory (NREL) and the Pacific Northwest National Laboratory (PNNL) are undertaking studies of biomass conversion technologies to hydrocarbon fuels to identify barriers and target research toward reducing conversion costs. Process designs and preliminary economic estimates for each of these pathway cases were developed using rigorous modeling tools (Aspen Plus and Chemcad). These analyses incorporated the best information available at the time of development, including data from recent pilot and bench-scale demonstrations, collaborative industrial and academic partners, and published literature and patents. This pathway case investigates the feasibility of using whole wet microalgae as a feedstock for conversion via <span class="hlt">hydrothermal</span> liquefaction. Technical barriers and key research needs have been assessed in order for the <span class="hlt">hydrothermal</span> liquefaction of microalgae to be competitive with petroleum-derived gasoline, diesel and jet range blendstocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060053345&hterms=Hydrothermal+vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Hydrothermal%2Bvents%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060053345&hterms=Hydrothermal+vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Hydrothermal%2Bvents%2529"><span id="translatedtitle">Modeling Microbiological Interactions with <span class="hlt">Hydrothermal</span> Flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoehler, Tori</p> <p>2006-01-01</p> <p>All organisms require energy. Characterizing and quantifying the biological demand for energy places constraints on the possible interactions of organisms with each other and with the environment. This talk will consider energetic and mass transfer constraints on the ecology of <span class="hlt">hydrothermal</span> vent microbes. Following a general introduction to the biological energy requirements and their link to environmental conditions, energy constraints will be applied to several vent-relevant case studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/369604','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/369604"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> reaction of fly ash. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brown, P.W.</p> <p>1994-12-31</p> <p>The reactions which occur when fly ash is treated under <span class="hlt">hydrothermal</span> conditions were investigated. This was done for the following primary reasons. The first of these is to determine the nature of the phases that form to assess the stabilities of these phases in the ambient environment and, finally, to assess whether these phases are capable of sequestering hazardous species. The second reason for undertaking this study was whether, depending on the composition of the ash and the presence of selected additives, it would be possible under <span class="hlt">hydrothermal</span> conditions to form compounds which have cementitious properties. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, were selected for study. The classes are calcium silicate hydrates, calcium selenates, and calcium aluminosulfates, and silicate-based glasses. Specific compounds synthesized were determined and their stability regions assessed. As part of stability assessment, the extent to which selected hazardous species are sequestered was determined. Finally, the cementing properties of these compounds were established. The results obtained in this program have demonstrated that mild <span class="hlt">hydrothermal</span> conditions can be employed to improve the reactivity of fly ash. Such improvements in reactivity can result in the formation of monolithic forms which may exhibit suitable mechanical properties for selected applications as building materials. If the ashes involved are considered hazardous, the mechanical properties exhibited indicated the forms could be handled in a manner which facilitates their disposal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUSMNG21A..04C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUSMNG21A..04C"><span id="translatedtitle">Modeling <span class="hlt">Hydrothermal</span> Mineralization: Fractal or Multifrcatal Models?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheng, Q.</p> <p>2004-05-01</p> <p><span class="hlt">Hydrothermal</span> mineralization occurs when the natural geo-processes involve the interaction of ore material-carrying <span class="hlt">hydrothermal</span> fluids with rocks in the earth's crust in a specific geological environment. Mineralization can cause element concentration enrichment or depletion in the country rocks. Local enrichment may form ore body that can be mined for profit at the current economic and technological conditions. To understand the spatial distribution of element concentration enrichment or depletion caused by mineralization in a mineral district is essential for mineral exploration and mineral prediction. Grade-tonnage model and mineral deposits size distribution model are common models used for characterizing mineral deposits. This paper proposes a non-linear mineralization model on the basis of a modified classical igneous differentiation mineralization model to describe the generation of multifractal distribution of element concentration in the country rocks as well as grade-tonnage fractal/multifractal distribution of ore deposits that have been often observed in <span class="hlt">hydrothermal</span> mineralization. This work may also lead to a singularity model to explain the common properties of mineralization and mineralization-associated geochemical anomaly diversity and the generalized self-similarity of the anomalies. The model has been applied to a case study of mineral deposits prediction and mineral resource assessment in the Abitibi district, northern Ontario, Canada.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5247351','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5247351"><span id="translatedtitle">Diffuse flow from <span class="hlt">hydrothermal</span> vents. Doctoral thesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Trivett, D.A.</p> <p>1991-08-01</p> <p>The effluent from a collection of diffuse <span class="hlt">hydrothermal</span> vents was modelled to determine the fate of the source of flow under typical environmental conditions at seafloor spreading centers. A laboratory simulation was conducted to test an analytic model of diffuse plume rise. The results showed that diffuse plumes are likely to remain near the seafloor, with their maximum rise height scaled with the diameter of the source of diffuse flow. The entrainment of ambient seawater into these plumes is limited by the proximity to the seafloor, thus slowing the rate of dilution. The model of diffuse plume behaviour was used to guide the design and implementation of a scheme for monitoring the flow from diffuse <span class="hlt">hydrothermal</span> vents in the ocean. A deployment of an array at the Southern Juan de Fuca Ridge yielded measurements of a variety of diffuse plume properties, including total heat output. Two distinct sources of <span class="hlt">hydrothermal</span> flow were detected during the field deployment. The larger source was 1-1.5km north of the instrument array, and its energy output was 450 + or - 270MW. A smaller source was located 100m east of one instrument in the array. The energy output of the source was 12 + or - 8MW. The rise heights of the centerlines of these plumes were 45m and 10m, respectively.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26482329','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26482329"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Formation of Calcium Copper Tetrasilicate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson-McDaniel, Darrah; Comer, Sara; Kolis, Joseph W; Salguero, Tina T</p> <p>2015-12-01</p> <p>We describe the first <span class="hlt">hydrothermal</span> synthesis of CaCuSi4 O10 as micron-scale clusters of thin platelets, distinct from morphologies generated under salt-flux or solid-state conditions. The <span class="hlt">hydrothermal</span> reaction conditions are surprisingly specific: too cold, and instead of CaCuSi4 O10 , a porous calcium copper silicate forms; too hot, and calcium silicate (CaSiO3 ) forms. The precursors also strongly impact the course of the reaction, with the most common side product being sodium copper silicate (Na2 CuSi4 O10 ). Optimized conditions for <span class="hlt">hydrothermal</span> CaCuSi4 O10 formation from calcium chloride, copper(II) nitrate, sodium silicate, and ammonium hydroxide are 350 °C at 3000 psi for 72 h; at longer reaction times, competitive delamination and exfoliation causes crystal fragmentation. These results illustrate that CaCuSi4 O10 is an even more unique material than previously appreciated. PMID:26482329</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034244','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034244"><span id="translatedtitle">Numerical simulation of magmatic <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ingebritsen, S.E.; Geiger, S.; Hurwitz, S.; Driesner, T.</p> <p>2010-01-01</p> <p>The dynamic behavior of magmatic <span class="hlt">hydrothermal</span> systems entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these systems depends mainly on numerical solution of coupled partial differential equations and complementary equations of state (EOS). The past 2 decades have seen steady growth of computational power and the development of numerical models that have eliminated or minimized the need for various simplifying assumptions. Considerable heuristic insight has been gained from process-oriented numerical modeling. Recent modeling efforts employing relatively complete EOS and accurate transport calculations have revealed dynamic behavior that was damped by linearized, less accurate models, including fluid property control of <span class="hlt">hydrothermal</span> plume temperatures and three-dimensional geometries. Other recent modeling results have further elucidated the controlling role of permeability structure and revealed the potential for significant <span class="hlt">hydrothermally</span> driven deformation. Key areas for future reSearch include incorporation of accurate EOS for the complete H2O-NaCl-CO2 system, more realistic treatment of material heterogeneity in space and time, realistic description of large-scale relative permeability behavior, and intercode benchmarking comparisons. Copyright 2010 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25867636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25867636"><span id="translatedtitle">Surface roughened zirconia: towards <span class="hlt">hydrothermal</span> stability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Camposilvan, Erik; Flamant, Quentin; Anglada, Marc</p> <p>2015-07-01</p> <p>Surface roughness is needed in several yttria-stabilized zirconia components used in restorative dentistry for osseointegration or adhesion purposes. This can be achieved by different treatments, which may also modify the microstructure of the surface. Among them, sandblasting and chemical etching are widely used, but their effect on <span class="hlt">hydrothermal</span> aging of zirconia is not fully understood. In the present work, the zirconia long-term stability of rough surfaces prepared by these techniques is analyzed and a method is proposed for preventing <span class="hlt">hydrothermal</span> aging while maintaining the original surface appearance and mechanical properties. The method involves pressure infiltration of a Cerium salt solution on the roughened surfaces followed by a thermal treatment. The solution, trapped by surface defects and small pores, is decomposed during thermal treatment into Cerium oxide, which is diffused at high temperature, obtaining Ce co-doping in the near-surface region. In addition, the microstructural changes induced in the near-surface by sandblasting or chemical etching are removed by the thermal treatment together with surface defects. No color modification was observed and the final roughness parameters were in the range of existing implants of proved good osseointegration. The aging resistance of Ce co-doped materials was strongly enhanced, showing the absence of aging after artificial degradation, increasing in this way the surface mechanical integrity. The proposed treatment is easily applicable to the current manufacturing procedures of zirconia dental posts, abutments, crowns and dentures, representing a solution to <span class="hlt">hydrothermal</span> aging in these and other biomedical applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5138293','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5138293"><span id="translatedtitle">Water column <span class="hlt">hydrothermal</span> plumes on the Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lupton, J.E. )</p> <p>1990-08-10</p> <p>Hydrographic surveys on the Juan de Fuca Ridge (JdFR) carried out from 1980 to 1987 show a complex pattern of {sup 3}He and Mn-rich water column plumes produced by venting from several submarine hot spring areas. In the vicinity of Axial Volcano at latitude 46{degree}N, distinct plumes were detected in 1980, 1982, and 1983 with {sup 3}He signatures up to {delta}({sup 3}He) = 64% at {approximately} 1,500 m depth at distances of {approximately} 10 km from the seamount summit. However, the same plumes had no detectable thermal signature, a paradox which is attributed to the high {sup 3}He/heat ratios and low salinities of the fluids venting within the caldera of Axial Volcano. Profiles directly over the seamount show <span class="hlt">hydrothermal</span> {sup 3}He in the water column up to 300 m above the caldera floor, with the {sup 3}He signal increasing with depth to very high and uniform ratios of {delta}({sup 3}He) = 108-150% below the {approximately} 1,500-m caldera sill depth. Another apparent locus of <span class="hlt">hydrothermal</span> input is Helium Basin, a depression on the northeast flank of Axial Volcano which had {delta}({sup 3}He) = 51% when first sampled in 1980. However, subsequent hydrocasts into Helium Basin in 1982 and 1983 yielded lower helium enrichments, suggesting either a decrease in <span class="hlt">hydrothermal</span> input or flushing of the basin via a mixing event. To the south of Axial Volcano, high {delta}({sup 3}He) values of {approximately} 40% observed over the ridge axis at 45{degree}18{prime}N and 45{degree}39{prime}N indicate venting on this previously unexplored section of the ridge. The water column plumes over the US Geological Survey vent <span class="hlt">site</span> at {approximately} 44{degree}40{prime}N on the southern JdFR have very high Mn/{sup 3}He ratios of 4,600 mol/cm{sup 3}, an apparently unique characteristic which can be used to distinguish these plumes from those originating at other JdFR vent fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25108489','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25108489"><span id="translatedtitle">Fate of copper complexes in <span class="hlt">hydrothermally</span> altered deep-sea sediments from the Central Indian Ocean Basin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chakraborty, Parthasarathi; Sander, Sylvia G; Jayachandran, Saranya; Nath, B Nagender; Nagaraju, G; Chennuri, Kartheek; Vudamala, Krushna; Lathika, N; Mascarenhas-Pereira, Maria Brenda L</p> <p>2014-11-01</p> <p>The current study aims to understand the speciation and fate of Cu complexes in <span class="hlt">hydrothermally</span> altered sediments from the Central Indian Ocean Basin and assess the probable impacts of deep-sea mining on speciation of Cu complexes and assess the Cu flux from this sediment to the water column in this area. This study suggests that most of the Cu was strongly associated with different binding <span class="hlt">sites</span> in Fe-oxide phases of the <span class="hlt">hydrothermally</span> altered sediments with stabilities higher than that of Cu-EDTA complexes. The speciation of Cu indicates that <span class="hlt">hydrothermally</span> influenced deep-sea sediments from Central Indian Ocean Basin may not significantly contribute to the global Cu flux. However, increasing lability of Cu-sediment complexes with increasing depth of sediment may increase bioavailability and Cu flux to the global ocean during deep-sea mining.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T13B2194G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T13B2194G"><span id="translatedtitle">Fluid Flow Patterns in a Submarine Volcano: Simulating the <span class="hlt">Hydrothermal</span> Evolution of Brothers Volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gruen, G.; de Ronde, C. E.; Driesner, T.; Heinrich, C. A.</p> <p>2010-12-01</p> <p>Brothers volcano is part of the southern Kermadec intra-oceanic arc located northeast of New Zealand, and is one of the world’s best-studied active submarine volcanoes. It provides insight into the complex subseafloor hydrology of a submarine arc volcano with evidence for different stages in its magmatic-<span class="hlt">hydrothermal</span> evolution [1]. The volcanic edifice comprises an elongated caldera surrounding an asymmetrically centered post-collapse cone. While <span class="hlt">hydrothermal</span> venting at the NW caldera wall is focused and dates back to at least 1,200 years, <span class="hlt">hydrothermal</span> discharge at the cone summit is diffuse and considered to be significantly younger. Recent studies of regional seismicity and local harmonic tremor at Brothers volcano imply the existence of a <span class="hlt">hydrothermal</span> fluid reservoir underneath the area of the present cone [2]. Using a combined finite element - finite volume method, we have computed multi-phase mass and heat transport with a process simulation scheme based on realistic fluid properties. We have used correlations that describe phase stability relations in the binary NaCl-H2O system up to 1000°C [3]. Our earlier results of generic fluid flow simulations showed that water depth and seafloor topography, together with crustal permeability and the relative contributions of seawater and magmatic fluids, are first-order physical parameters controlling the fluid flow patterns and the style of <span class="hlt">hydrothermal</span> venting. In our more recent simulations, we use available data from Brothers volcano, including detailed bathymetry, physical and chemical measurements from different vent <span class="hlt">sites</span> and information on the size and location of the subseafloor magma chamber(s). The implementation of two distinct magmatic stages (i.e., pre-cone vs. post-cone) shows that the topography of the volcanic edifice, in combination with the location and size of an underlying magma chamber, play an important role in the style and evolution of the <span class="hlt">hydrothermal</span> system. [1] de Ronde, C. E. J., et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.B51D0423R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.B51D0423R"><span id="translatedtitle">Methanethiol abundance in high-temperature <span class="hlt">hydrothermal</span> fluids from the Mid-Atlantic Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reeves, E.; Seewald, J. S.; Saccocia, P.; van der Meer, M.</p> <p>2008-12-01</p> <p>The formation of aqueous organic sulfur compounds in <span class="hlt">hydrothermal</span> systems remains poorly constrained, despite their potential significance in 'prebiotic' chemistry and the origin of life. The simplest - methanethiol (CH3SH) - has been implicated as a critical abiogenic precursor to the establishment of primitive microbial metabolism in early Earth <span class="hlt">hydrothermal</span> settings. It also represents a readily-utilized substrate for microbial sulfate-reducing communities and a potential intermediate species in abiotic CH4 formation. To assess the abundance of CH3SH and factors regulating its stability under <span class="hlt">hydrothermal</span> conditions we measured CH3SH concentrations in a suite of <span class="hlt">hydrothermal</span> fluids collected from the Rainbow, Lucky Strike, TAG and Lost City <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> located on the Mid-Atlantic Ridge. Fluids were collected using isobaric gas-tight samplers and analyzed for CH3SH by shipboard purge-and-trap gas chromatography. Measured concentrations at Rainbow (1.2 -- 223nM), Lucky Strike (1.1 -- 26nM), TAG (8.5 -- 11nM) and Lost City (1.6 -- 3.0nM) are all substantially lower than predicted for thermodynamic equilibrium with CO2, H2 and H2S at measured vent conditions. The highest concentrations (91 -- 223nM), however, were observed at Rainbow in intermediate temperature (128 -- 175°C) H2-rich fluids that may have undergone conductive cooling. Increased concentrations with decreasing temperature is consistent with the thermodynamic drive for the formation from CO2, suggesting a possible abiotic origin for CH3SH in some fluids. Substantially lower concentrations in the low temperature fluids at Lost City are consistent with the extremely low levels of CO2 and H2S in these fluids. Other possible sources of CH3SH to vent fluids must be considered, however, and include thermal alteration of biomass present in low-temperature environments and microbial consortia that produce CH3SH as a byproduct of anaerobic methane oxidation. Current models for the emergence of primordial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616710Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616710Y"><span id="translatedtitle">Dynamic drivers of a shallow-water <span class="hlt">hydrothermal</span> vent ecogeochemical system (Milos, Eastern Mediterranean)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yücel, Mustafa; Sievert, Stefan; Giovanelli, Donato; Foustoukos, Dionysis; DeForce, Emelia; Thomas, François; Vetriani, Constantino; Le Bris, Nadine</p> <p>2014-05-01</p> <p> the metabolic activities and the environmental factors shaping these microbial communities . Both bacterial and archaeal diversity changed along the transect as well as with sediment depth, in line with the geochemical measurements. Beside the fact that it harbors an unexpected diversity of yet undescribed bacteria and archaea, this <span class="hlt">site</span> is also a relevant model to investigate the link between ecological and abiotic dynamics in such instable <span class="hlt">hydrothermal</span> environments. Our results provide evidence for the importance of transient geodynamic and hydrodynamic events in the dynamics and distribution of chemoautotrophic communities in the <span class="hlt">hydrothermally</span> influenced sediments of Paleochori Bay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.105..108D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.105..108D"><span id="translatedtitle">Quantitative models of <span class="hlt">hydrothermal</span> fluid-mineral reaction: The Ischia case</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Di Napoli, Rossella; Federico, Cinzia; Aiuppa, Alessandro; D'Antonio, Massimo; Valenza, Mariano</p> <p>2013-03-01</p> <p>The intricate pathways of fluid-mineral reactions occurring underneath active <span class="hlt">hydrothermal</span> systems are explored in this study by applying reaction path modelling to the Ischia case study. Ischia Island, in Southern Italy, hosts a well-developed and structurally complex <span class="hlt">hydrothermal</span> system which, because of its heterogeneity in chemical and physical properties, is an ideal test <span class="hlt">sites</span> for evaluating potentialities/limitations of quantitative geochemical models of <span class="hlt">hydrothermal</span> reactions. We used the EQ3/6 software package, version 7.2b, to model reaction of infiltrating waters (mixtures of meteoric water and seawater in variable proportions) with Ischia's reservoir rocks (the Mount Epomeo Green Tuff units; MEGT). The mineral assemblage and composition of such MEGT units were initially characterised by ad hoc designed optical microscopy and electron microprobe analysis, showing that phenocrysts (dominantly alkali-feldspars and plagioclase) are set in a pervasively altered (with abundant clay minerals and zeolites) groundmass. Reaction of infiltrating waters with MEGT minerals was simulated over a range of realistic (for Ischia) temperatures (95-260 °C) and CO2 fugacities (10-0.2 to 100.5) bar. During the model runs, a set of secondary minerals (selected based on independent information from alteration minerals' studies) was allowed to precipitate from model solutions, when saturation was achieved. The compositional evolution of model solutions obtained in the 95-260 °C runs were finally compared with compositions of Ischia's thermal groundwaters, demonstrating an overall agreement. Our simulations, in particular, well reproduce the Mg-depleting maturation path of <span class="hlt">hydrothermal</span> solutions, and have end-of-run model solutions whose Na-K-Mg compositions well reflect attainment of full-equilibrium conditions at run temperature. High-temperature (180-260 °C) model runs are those best matching the Na-K-Mg compositions of Ischia's most chemically mature water samples</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998GeoRL..25...97S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeoRL..25...97S"><span id="translatedtitle">Detection of <span class="hlt">hydrothermal</span> plumes along the Southeast Indian Ridge near the Amsterdam-St. Paul Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scheirer, Daniel S.; Baker, Edward T.; Johnson, Kevin T. M.</p> <p></p> <p>A new self-contained profiling instrument, attached to 91 lowerings of waxcores and dredges along a 1600 km stretch of the Southeast Indian Ridge, found six <span class="hlt">sites</span> having optical back-scatter anomalies indicative of <span class="hlt">hydrothermal</span> plumes from high-temperature seafloor venting. At five other <span class="hlt">sites</span>, back-scatter anomalies were less distinct, and at the remaining <span class="hlt">sites</span>, anomalies were absent. These are the first documented <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> along this intermediate-rate spreading center and are among the very few yet discovered in the Indian Ocean basin. Some profiles exhibit complex back-scatter anomalies suggestive of multiple sources of seafloor discharge. At one <span class="hlt">site</span>, near-bottom temperature anomalies of ∼0.1°C and the recovery of a vent-specific barnacle provide the first precise seafloor location of active venting in the deep Indian Ocean. Although this study is only reconnaissance in nature, venting along this portion of the SEIR appears to be significantly less than predicted by global correlations of plume incidence as a function of spreading rate. Nevertheless, these <span class="hlt">sites</span> may be important as biological connections between distinct faunal assemblages of Atlantic and Pacific vent fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..314..142W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..314..142W"><span id="translatedtitle">High-resolution water column survey to identify active sublacustrine <span class="hlt">hydrothermal</span> discharge zones within Lake Rotomahana, North Island, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walker, Sharon L.; de Ronde, Cornel E. J.; Fornari, Daniel; Tivey, Maurice A.; Stucker, Valerie K.</p> <p>2016-03-01</p> <p>Autonomous underwater vehicles were used to conduct a high-resolution water column survey of Lake Rotomahana using temperature, pH, turbidity, and oxidation-reduction potential (ORP) to identify active <span class="hlt">hydrothermal</span> discharge zones within the lake. Five areas with active sublacustrine venting were identified: (1) the area of the historic Pink Terraces; (2) adjacent to the western shoreline subaerial "Steaming Cliffs," boiling springs and geyser; (3) along the northern shoreline to the east of the Pink Terrace <span class="hlt">site</span>; (4) the newly discovered Patiti <span class="hlt">hydrothermal</span> system along the south margin of the 1886 Tarawera eruption rift zone; and (5) a location in the east basin (northeast of Patiti Island). The Pink Terrace <span class="hlt">hydrothermal</span> system was active prior to the 1886 eruption of Mount Tarawera, but venting along the western shoreline, in the east basin, and the Patiti <span class="hlt">hydrothermal</span> system appear to have been initiated in the aftermath of the eruption, similar to Waimangu Valley to the southwest. Different combinations of turbidity, pH anomalies (both positive and negative), and ORP responses suggest vent fluid compositions vary over short distances within the lake. The seasonal period of stratification limits vertical transport of heat to the surface layer and the hypolimnion temperature of Lake Rotomahana consequently increases with an average warming rate of ~ 0.010 °C/day due to both convective <span class="hlt">hydrothermal</span> discharge and conductive geothermal heating. A sudden temperature increase occurred during our 2011 survey and was likely the response to an earthquake swarm just 11 days prior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.1124T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.1124T"><span id="translatedtitle">Modes of crustal accretion and their implications for <span class="hlt">hydrothermal</span> circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Theissen-Krah, Sonja; Rüpke, Lars H.; Hasenclever, Jörg</p> <p>2016-02-01</p> <p><span class="hlt">Hydrothermal</span> convection at mid-ocean ridges links the ocean's long-term chemical evolution to solid earth processes, forms <span class="hlt">hydrothermal</span> ore deposits, and sustains the unique chemosynthetic vent fauna. Yet the depth extent of <span class="hlt">hydrothermal</span> cooling and the inseparably connected question of how the lower crust accretes remain poorly constrained. Here based on coupled models of crustal accretion and <span class="hlt">hydrothermal</span> circulation, we provide new insights into which modes of lower crust formation and <span class="hlt">hydrothermal</span> cooling are thermally viable and most consistent with observations at fast-spreading ridges. We integrate numerical models with observations of melt lens depth, thermal structure, and melt fraction. Models matching all these observations always require a deep crustal-scale <span class="hlt">hydrothermal</span> flow component and less than 50% of the lower crust crystallizing in situ.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032354','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032354"><span id="translatedtitle">Searching for evidence of <span class="hlt">hydrothermal</span> activity at Apollinaris Mons, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>El Maarry, M.R.; Dohm, J.M.; Marzo, G.A.; Fergason, R.; Goetz, W.; Heggy, E.; Pack, A.; Markiewicz, W.J.</p> <p>2012-01-01</p> <p>A multidisciplinary approach involving various remote sensing instruments is used to investigate Apollinaris Mons, a prominent volcano on Mars, as well as the surrounding plains for signs of prolonged hydrologic and volcanic, and possibly <span class="hlt">hydrothermal</span> activity. The main findings include (1) evidence from laser altimetry indicating the large thickness (1.5-2. km at some locations) of the fan deposits draping the southern flank contrary to previous estimates, coupled with possible layering which point to a significant emplacement phase at Apollinaris Mons, (2) corroboration of Robinson et al. (Robinson, M.S., Mouginis-Mark, P.J., Zimbelman, J.R., Wu, S.S.C., Ablin, K.K., Howington-Kraus, A.E. [1993]. Icarus 104, 301-323) hypothesis regarding the formation of incised valleys on the western flanks by density current erosion which would indicate magma-water interaction or, alternatively, volatile-rich magmas early in the volcano's history, (3) mounds of diverse geometric shapes, many of which display summit depressions and occur among faults and fractures, possibly marking venting, (4) strong indicators on the flanks of the volcano for lahar events, and possibly, a caldera lake, (5) ubiquitous presence of impact craters displaying fluidized ejecta in both shield-forming (flank and caldera) materials and materials that surround the volcano that are indicative of water-rich target materials at the time of impact, (6) long-term complex association in time among shield-forming materials and Medusae Fossae Formation.The findings point to a <span class="hlt">site</span> of extensive volcanic and hydrologic activity with possibly a period of magma-water interaction and <span class="hlt">hydrothermal</span> activity. Finally, we propose that the mound structures around Apollinaris should be prime targets for further in situ exploration and search for possible exobiological signatures. ?? 2011 Elsevier Inc..</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70039299','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70039299"><span id="translatedtitle">Searching for evidence of <span class="hlt">hydrothermal</span> activity at Apollinaris Mons, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>El Maarry, M. Ramy; Dohm, James M.; Marzo, Giuseppe A.; Fergason, Robin; Goetz, Walter; Heggy, Essam; Pack, Andreas; Markiewicz, Wojciech J.</p> <p>2012-01-01</p> <p>A multidisciplinary approach involving various remote sensing instruments is used to investigate Apollinaris Mons, a prominent volcano on Mars, as well as the surrounding plains for signs of prolonged hydrologic and volcanic, and possibly <span class="hlt">hydrothermal</span> activity. The main findings include (1) evidence from laser altimetry indicating the large thickness (1.5–2 km at some locations) of the fan deposits draping the southern flank contrary to previous estimates, coupled with possible layering which point to a significant emplacement phase at Apollinaris Mons, (2) corroboration of Robinson et al. (Robinson, M.S., Mouginis-Mark, P.J., Zimbelman, J.R., Wu, S.S.C., Ablin, K.K., Howington-Kraus, A.E. [1993]. Icarus 104, 301–323) hypothesis regarding the formation of incised valleys on the western flanks by density current erosion which would indicate magma–water interaction or, alternatively, volatile-rich magmas early in the volcano’s history, (3) mounds of diverse geometric shapes, many of which display summit depressions and occur among faults and fractures, possibly marking venting, (4) strong indicators on the flanks of the volcano for lahar events, and possibly, a caldera lake, (5) ubiquitous presence of impact craters displaying fluidized ejecta in both shield-forming (flank and caldera) materials and materials that surround the volcano that are indicative of water-rich target materials at the time of impact, (6) long-term complex association in time among shield-forming materials and Medusae Fossae Formation. The findings point to a <span class="hlt">site</span> of extensive volcanic and hydrologic activity with possibly a period of magma–water interaction and <span class="hlt">hydrothermal</span> activity. Finally, we propose that the mound structures around Apollinaris should be prime targets for further in situ exploration and search for possible exobiological signatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.6314D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.6314D&link_type=ABSTRACT"><span id="translatedtitle">Modelling magmatic gas scrubbing in <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Di Napoli, Rossella; Aiuppa, Alessandro; Valenza, Mariano; Bergsson, Baldur; Ilyinskaya, Evgenia; Pfeffer, Melissa Anne; Rakel Guðjónsdóttir, Sylvía</p> <p>2015-04-01</p> <p>In volcano-hosted <span class="hlt">hydrothermal</span> systems, the chemistry of deeply rising magmatic gases is extensively modified by gas-water-rock interactions taking place within the <span class="hlt">hydrothermal</span> reservoir, and/or at shallow groundwaters conditions. These reactions can scrub reactive, water-soluble species (S, halogens) from the magmatic gas phase, so that their quantitative assessment is central to understanding the chemistry of surface gas manifestations, and brings profound implications to the interpretation of volcanic-<span class="hlt">hydrothermal</span> unrests. Here, we present the results of numerical simulations of magmatic gas scrubbing, in which the reaction path modelling approach (Helgeson, 1968) is used to reproduce <span class="hlt">hydrothermal</span> gas-water-rock interactions at both shallow (temperature up to 109°C; low-T model runs) and deep reservoir (temperature range: 150-250 °C; high-T model runs) conditions. The model was built based upon the EQ3/6 software package (Wolery and Daveler, 1992), and consisted into a step by step addition of a high-temperature magmatic gas to an initial meteoric water, in the presence of a dissolving aquifer rock. The model outputted, at each step of gas addition, the chemical composition of a new aqueous solution formed after gas-water-rock interactions; which, upon reaching gas over-pressuring (PgasTOT > Psat(H2O) at run T), is degassed (by single-step degassing) to separate a scrubbed gas phase. As an application of the model results, the model compositions of the separated gases are finally compared with compositions of natural gas emissions from Hekla volcano (T< 100°C) and from Krisuvik geothermal system (T> 100°C), resulting into an excellent agreement. The compositions of the model solutions are also in fair agreement with compositions of natural thermal water samples. We conclude that our EQ3/6-based reaction path simulations offer a realistic representation of gas-water-rock interaction processes occurring underneath active magmatic-<span class="hlt">hydrothermal</span> systems</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22012101','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22012101"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis map of bismuth titanates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sardar, Kripasindhu; Walton, Richard I.</p> <p>2012-05-15</p> <p>The <span class="hlt">hydrothermal</span> synthesis of four bismuth titanate materials from common bismuth and titanium precursors under <span class="hlt">hydrothermal</span> conditions is described. Reaction of NaBiO{sub 3}{center_dot}2H{sub 2}O and anatase TiO{sub 2} in concentrated NaOH solution at 240 Degree-Sign C is shown to produce perovskite and sillenite phases Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} and Bi{sub 12}TiO{sub 20}, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi{sub 1.43}Ti{sub 2}O{sub 6}(OH){sub 0.29}(H{sub 2}O){sub 0.66} is formed. The use of a mixture of HNO{sub 3} and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi{sub 4}Ti{sub 3}O{sub 12}. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi L{sub III}-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the <span class="hlt">hydrothermally</span> derived products. - Graphical abstract: Use of NaBiO{sub 3}{center_dot}2H{sub 2}O and TiO{sub 2} as reagents under <span class="hlt">hydrothermal</span> conditions allows the phase-pure preparation of four crystalline bismuth titanate materials. Highlights: Black-Right-Pointing-Pointer NaBiO{sub 3} and TiO{sub 2} under <span class="hlt">hydrothermal</span> conditions allow formation of bismuth titanates. Black-Right-Pointing-Pointer Synthesis of four distint phases has been mapped. Black-Right-Pointing-Pointer Bi LIII-edge XANES shows Bi is reduced to oxidation state +3 in all materials. Black-Right-Pointing-Pointer A new hydrated bismuth titanate pyrochlore has been isolated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25902075','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25902075"><span id="translatedtitle">Post-drilling changes in seabed landscape and megabenthos in a deep-sea <span class="hlt">hydrothermal</span> system, the Iheya North field, Okinawa Trough.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken</p> <p>2015-01-01</p> <p>There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea <span class="hlt">hydrothermal</span> fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea <span class="hlt">hydrothermal</span> field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling <span class="hlt">site</span> (<span class="hlt">Site</span> C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling <span class="hlt">sites</span> of IODP Exp. 331. No visible <span class="hlt">hydrothermal</span> fluid discharge had been observed at the sedimentary seafloor at <span class="hlt">Site</span> C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature <span class="hlt">hydrothermal</span> fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new <span class="hlt">hydrothermal</span> vent habitat. Widespread microbial mats developed on the seafloor with the diffusing <span class="hlt">hydrothermal</span> fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established <span class="hlt">hydrothermal</span> vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25902075','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25902075"><span id="translatedtitle">Post-drilling changes in seabed landscape and megabenthos in a deep-sea <span class="hlt">hydrothermal</span> system, the Iheya North field, Okinawa Trough.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken</p> <p>2015-01-01</p> <p>There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea <span class="hlt">hydrothermal</span> fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea <span class="hlt">hydrothermal</span> field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling <span class="hlt">site</span> (<span class="hlt">Site</span> C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling <span class="hlt">sites</span> of IODP Exp. 331. No visible <span class="hlt">hydrothermal</span> fluid discharge had been observed at the sedimentary seafloor at <span class="hlt">Site</span> C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature <span class="hlt">hydrothermal</span> fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new <span class="hlt">hydrothermal</span> vent habitat. Widespread microbial mats developed on the seafloor with the diffusing <span class="hlt">hydrothermal</span> fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established <span class="hlt">hydrothermal</span> vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4406493','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4406493"><span id="translatedtitle">Post-Drilling Changes in Seabed Landscape and Megabenthos in a Deep-Sea <span class="hlt">Hydrothermal</span> System, the Iheya North Field, Okinawa Trough</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken</p> <p>2015-01-01</p> <p>There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea <span class="hlt">hydrothermal</span> fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea <span class="hlt">hydrothermal</span> field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling <span class="hlt">site</span> (<span class="hlt">Site</span> C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling <span class="hlt">sites</span> of IODP Exp. 331. No visible <span class="hlt">hydrothermal</span> fluid discharge had been observed at the sedimentary seafloor at <span class="hlt">Site</span> C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature <span class="hlt">hydrothermal</span> fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, ‘artificially’ creating a new <span class="hlt">hydrothermal</span> vent habitat. Widespread microbial mats developed on the seafloor with the diffusing <span class="hlt">hydrothermal</span> fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established <span class="hlt">hydrothermal</span> vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009DSRII..56.1632L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009DSRII..56.1632L"><span id="translatedtitle">Macrobenthos community structure and trophic relationships within active and inactive Pacific <span class="hlt">hydrothermal</span> sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Levin, Lisa A.; Mendoza, Guillermo F.; Konotchick, Talina; Lee, Raymond</p> <p>2009-09-01</p> <p><span class="hlt">Hydrothermal</span> fluids passing through sediments create a habitat hypothesized to influence the community structure of infaunal macrobenthos. Here we characterize the density, biomass, species composition, diversity, distributions, lifestyle, and nutritional sources of macroinfauna in <span class="hlt">hydrothermal</span> sediments in NE and SW Pacific settings, and draw comparisons in search of faunal attributes characteristic of this habitat. There is increasing likelihood that seafloor massive sulfide deposits, associated with active and inactive <span class="hlt">hydrothermal</span> venting, will be mined commercially. This creates a growing imperative for a more thorough understanding of the structure, dynamics, and resilience of the associated sediment faunas, and has stimulated the research presented here. Macrobenthic assemblages were studied at Manus Basin (1430-1634 m, Papua New Guinea [PNG]) as a function of location (South Su vs. Solwara 1), and <span class="hlt">hydrothermal</span> activity (active vs. inactive), and at Middle Valley (2406-2411 m, near Juan de Fuca Ridge) as a function of habitat (active clam bed, microbial mat, hot mud, inactive background sediment). The studies conducted in PNG formed part of the environmental impact assessment work for the Solwara 1 Project of Nautilus Minerals Niugini Limited. We hypothesized that <span class="hlt">hydrothermally</span> active <span class="hlt">sites</span> should support (a) higher densities and biomass, (b) greater dominance and lower diversity, (c) a higher fraction of deposit feeders, and (d) greater isotopic evidence for chemosynthetic food sources than inactive <span class="hlt">sites</span>. Manus Basin macrofauna generally had low density (<1000 ind. m -2) and low biomass (0.1-1.07 g m -2), except for the South Su active <span class="hlt">site</span>, which had higher density (3494 ind. m -2) and biomass (11.94 g m -2), greater dominance (R1D=76%), lower diversity and more spatial (between-core) homogeneity than the Solwara 1 and South Su inactive <span class="hlt">sites</span>. Dominant taxa at Manus Basin were Spionidae ( Prionospio sp.) in active sediments, and tanaids and deposit</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20533949','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20533949"><span id="translatedtitle">Bacterial diversity in Fe-rich <span class="hlt">hydrothermal</span> sediments at two South Tonga Arc submarine volcanoes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Forget, N L; Murdock, S A; Juniper, S K</p> <p>2010-12-01</p> <p>Seafloor iron oxide deposits are a common feature of submarine <span class="hlt">hydrothermal</span> systems. Morphological study of these deposits has led investigators to suggest a microbiological role in their formation, through the oxidation of reduced Fe in <span class="hlt">hydrothermal</span> fluids. Fe-oxidizing bacteria, including the recently described Zetaproteobacteria, have been isolated from a few of these deposits but generally little is known about the microbial diversity associated with this habitat. In this study, we characterized bacterial diversity in two Fe oxide samples collected on the seafloor of Volcanoes 1 and 19 on the South Tonga Arc. We were particularly interested in confirming the presence of Zetaproteobacteria at these two <span class="hlt">sites</span> and in documenting the diversity of groups other than Fe oxidizers. Our results (small subunit rRNA gene sequence data) showed a surprisingly high bacterial diversity, with 150 operational taxonomic units belonging to 19 distinct taxonomic groups. Both samples were dominated by Zetaproteobacteria Fe oxidizers. This group was most abundant at Volcano 1, where sediments were richer in Fe and contained more crystalline forms of Fe oxides. Other groups of bacteria found at these two <span class="hlt">sites</span> include known S- and a few N-metabolizing bacteria, all ubiquitous in marine environments. The low similarity of our clones with the GenBank database suggests that new species and perhaps new families were recovered. The results of this study suggest that Fe-rich <span class="hlt">hydrothermal</span> sediments, while dominated by Fe oxidizers, can be exploited by a variety of autotrophic and heterotrophic micro-organisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20533949','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20533949"><span id="translatedtitle">Bacterial diversity in Fe-rich <span class="hlt">hydrothermal</span> sediments at two South Tonga Arc submarine volcanoes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Forget, N L; Murdock, S A; Juniper, S K</p> <p>2010-12-01</p> <p>Seafloor iron oxide deposits are a common feature of submarine <span class="hlt">hydrothermal</span> systems. Morphological study of these deposits has led investigators to suggest a microbiological role in their formation, through the oxidation of reduced Fe in <span class="hlt">hydrothermal</span> fluids. Fe-oxidizing bacteria, including the recently described Zetaproteobacteria, have been isolated from a few of these deposits but generally little is known about the microbial diversity associated with this habitat. In this study, we characterized bacterial diversity in two Fe oxide samples collected on the seafloor of Volcanoes 1 and 19 on the South Tonga Arc. We were particularly interested in confirming the presence of Zetaproteobacteria at these two <span class="hlt">sites</span> and in documenting the diversity of groups other than Fe oxidizers. Our results (small subunit rRNA gene sequence data) showed a surprisingly high bacterial diversity, with 150 operational taxonomic units belonging to 19 distinct taxonomic groups. Both samples were dominated by Zetaproteobacteria Fe oxidizers. This group was most abundant at Volcano 1, where sediments were richer in Fe and contained more crystalline forms of Fe oxides. Other groups of bacteria found at these two <span class="hlt">sites</span> include known S- and a few N-metabolizing bacteria, all ubiquitous in marine environments. The low similarity of our clones with the GenBank database suggests that new species and perhaps new families were recovered. The results of this study suggest that Fe-rich <span class="hlt">hydrothermal</span> sediments, while dominated by Fe oxidizers, can be exploited by a variety of autotrophic and heterotrophic micro-organisms. PMID:20533949</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V13D..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V13D..03S"><span id="translatedtitle">Spatial and Temporal Changes to Water Chemistry and Heat Flux of the Lake Rotomahana <span class="hlt">Hydrothermal</span> System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stucker, V. K.; Tivey, M.; Lupton, J. E.; Walker, S. L.; Fornari, D. J.; de Ronde, C. E. J.</p> <p>2014-12-01</p> <p>Lake Rotomahana (North Island, New Zealand) is a crater lake with prominent <span class="hlt">hydrothermal</span> venting. Water column studies were conducted in 2011 and 2014 to complement magnetic, seismic, bathymetric and heat flux surveys, respectively. Results from the heat flow survey indicate that Lake Rotomahana is getting warmer relative to historic measurements, with individual stations within the lake releasing heat in excess of 60 Watts/m2. Helium sources are found at the lake floor at depths of ~50 meters and ~100m. Helium concentrations below 50 m depth have increased with high statistical significance over the three years between surveys and represent some of the highest concentrations ever measured at 6x107 ccSTP/g with an end-member 3He/4He value of 7.1 Ra. <span class="hlt">Hydrothermal</span> activity comprises a significant portion of the inputs to Lake Rotomahana, as evidenced by δD and δ18O values, as well as ratios of conservative elements such as boron and chloride. Waters collected from lakeshore hot springs show geographic differences in geothermal source temperature using a Na-K geothermometer, with inferred reservoir temperatures ranging from 200 to 230°C. Lake Rotomahana was in part the focus of the 1886 Tarawera eruption; our results show both pre-eruption <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> and newly created post-eruption <span class="hlt">sites</span> are active and should be monitored for continued changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B13A0164P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B13A0164P"><span id="translatedtitle">Sulfate Reduction and Sulfide Biomineralization By Deep-Sea <span class="hlt">Hydrothermal</span> Vent Microorganisms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Picard, A.; Gartman, A.; Clarke, D. R.; Girguis, P. R.</p> <p>2014-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents are characterized by steep temperature and chemical gradients and moderate pressures. At these <span class="hlt">sites</span>, mesophilic sulfate-reducing bacteria thrive, however their significance for the formation of sulfide minerals is unknown. In this study we investigated sulfate reduction and sulfide biomineralization by the deep-sea bacterium Desulfovibrio hydrothermalis isolated from a deep-sea vent chimney at the Grandbonum vent <span class="hlt">site</span> (13°N, East Pacific Rise, 2600 m water depth) [1]. Sulfate reduction rates were determined as a function of pressure and temperature. Biomineralization of sulfide minerals in the presence of various metal concentrations was characterized using light and electron microscopy and optical spectroscopy. We seek to better understand the significance of biological sulfate reduction in deep-sea <span class="hlt">hydrothermal</span> environments, to characterize the steps in sulfide mineral nucleation and growth, and identify the interactions between cells and minerals. [1] D. Alazard, S. Dukan, A. Urios, F. Verhe, N. Bouabida, F. Morel, P. Thomas, J.L. Garcia and B. Ollivier, Desulfovibrio hydrothermalis sp. nov., a novel sulfate-reducing bacterium isolated from <span class="hlt">hydrothermal</span> vents, Int. J. Syst. Evol. Microbiol., 53 (2003) 173-178.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016511','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016511"><span id="translatedtitle">Conditions leading to a recent small <span class="hlt">hydrothermal</span> explosion at Yellowstone National Park</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fournier, R.O.; Thompson, J.M.; Cunningham, C.G.; Hutchinson, R.A.</p> <p>1991-01-01</p> <p>Porkchop Geyser, in Yellowstone National Park, was the <span class="hlt">site</span> of a small <span class="hlt">hydrothermal</span> explosion on September 5, 1989. The geyser column suddenly rose to a height of 20-30 m, followed immediately by the explosive ejection of sinter blocks up to 1.88 m in maximum dimension and formation of an irregular crater 13.9 m long and 11.7 m wide. The ejected blocks show a variety of siliceous deposits indicative of changing environments of deposition with time, and possibly of prior <span class="hlt">hydrothermal</span> explosive activity at this <span class="hlt">site</span>. Water samples from Porkchop were collected and analyzed once in the 1920s, again in 1951, ten times between 1960 and mid-1989, and once in January 1990 after the explosion. It is hypothesized that a sudden breaking loose of the constriction at the exit of the geyser tube, likely triggered by a seasonal increase in subsurface boiling throughout Norris Basin, allowed water and steam to be discharged from Porkchop much more rapidly than previously. This resulted in a drop in pressure within the geyser tube, causing water in adjacent connected chambers to become superheated. An ensuing rapid flashing of superheated water to steam within relatively confined spaces resulted in the <span class="hlt">hydrothermal</span> explosion. -after Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V21A4733M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V21A4733M"><span id="translatedtitle">The scale of <span class="hlt">hydrothermal</span> circulation of the Iheya-North field inferred from intensive heat flow measurements and ocean drilling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masaki, Y.; Kinoshita, M.; Yamamoto, H.; Nakajima, R.; Kumagai, H.; Takai, K.</p> <p>2014-12-01</p> <p>Iheya-North <span class="hlt">hydrothermal</span> field situated in the middle Okinawa trough backarc basin is one of the largest ongoing Kuroko deposits in the world. Active chimneys as well as diffuse ventings (maximum fluid temperature 311 °C) have been located and studied in detail through various geological and geophysical surveys. To clarify the spatial scale of the <span class="hlt">hydrothermal</span> circulation system, intensive heat flow measurements were carried out and ~100 heat flow data in and around the field from 2002 to 2014. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 was carried out, and subbottom temperature data were obtained around the <span class="hlt">hydrothermal</span> <span class="hlt">sites</span>. During the JAMSTEC R/V Kaiyo cruise, KY14-01 in 2014, Iheya-North "Natsu" and "Aki" <span class="hlt">hydrothermal</span> fields were newly found. The Iheya-Noth "Natsu" and "Aki" <span class="hlt">sites</span> are located 1.2 km and 2.6 km south from the Iheya-North original <span class="hlt">site</span>, respectively, and the maximum venting fluid temperature was 317 °C. We obtained one heat flow data at the "Aki" <span class="hlt">site</span>. The value was 17 W/m2. Currently, the relationship between these <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> are not well known. Three distinct zones are identified by heat flow values within 3 km from the active <span class="hlt">hydrothermal</span> field. They are high-heat flow zone (>1 W/m2; HHZ), moderate-heat-flow zone (1-0.1 W/m2; MHZ); and low-heat-flow zone (<0.1 W/m2; LHZ). With increasing distance east of the HHZ, heat flow gradually decreases towards MHZ and LHZ. In the LHZ, temperature at 37m below the seafloor (mbsf) was 6 °C, that is consistent with the surface low heat flow suggesting the recharge of seawater. However, between 70 and 90 mbsf, the coarser sediments were cored, and temperature increased from 25 °C to 40°C. The temperature was 905°C at 151 mbsf, which was measured with thermoseal strips. The low thermal gradient in the upper 40 m suggests downward fluid flow. We infer that a <span class="hlt">hydrothermal</span> circulation in the scale of ~1.5 km horizontal vs. ~a few hundred meters vertical.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.V41B1389T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V41B1389T"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> circulation system in the central Mariana illustrated by Magnetometoric Resistivity experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tada, N.; Seama, N.; Goto, T.; Kido, M.</p> <p>2004-12-01</p> <p><span class="hlt">Hydrothermal</span> vent fields are known to exist on the spreading axis, where sea water penetrates into the crust and upwells through the <span class="hlt">hydrothermal</span> vents. Understanding of the <span class="hlt">hydrothermal</span> circulation system is extremely important to reveal the cooling process of the oceanic crust. The thermal structure beneath the <span class="hlt">hydrothermal</span> vent reflects the extent of underground activity and the convection scale of the hot water. Temperature in the crust can be estimated from the electrical conductivity because the conductivity depends on the water volume, the salinity concentration and the temperature of the sea water in the crust. The Alice Spring Field (18 o12.9'N, 144 o42.5'E and 3600m deep), on the spreading axis in the central Mariana Back-Arc Basin, is a suitable <span class="hlt">site</span> for this purpose. <span class="hlt">Hydrothermal</span> vent in this field was firstly discovered by Alvin in 1987 (Hawkins et al., 1990). Shinkai6500 also confirmed the <span class="hlt">hydrothermal</span> activity in 1992 and 1996 (Gamou et al., 1994; Fujikura et al., 1997). In November, 2002, we conducted Magnetometric Resistivity (MMR) survey using R/V Kairei, JAMSTEC in this field. In the MMR method, controlled electric current was applied from a pair of electrodes; one is just beneath the sea surface and the other is close to the seafloor. To record electoromagnetic responses of the crust to the inputed current, we deployed six ocean bottom electromagnetometers (OBEMs), which can measure 3-components of magnetic and electric fields simultaneously. Measurements were conducted at 34 <span class="hlt">sites</span> around the field, each of which consists of 30 minutes stacking for repeated current signals to keep better S/N ratio. Apparent resistivity is given by a function of amplitudes of magnetic field variation and source-receiver distance. We recovered the data from four OBEMs (two were on the spreading axis and other two were off axis). The plot of magnetic amplitudes to source-receiver distances shows different trend between OBEMs on-axis and off-axis. Therefore, we</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1240510','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1240510"><span id="translatedtitle">Synthesis of Nanoparticles via Solvothermal and <span class="hlt">Hydrothermal</span> Methods</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Li, Jianlin; Wu, Qingliu; Wu, Ji</p> <p>2015-01-01</p> <p>This chapter summarizes the synthesis of various types of nanoparticles as well as surface modifications of nanomaterials using <span class="hlt">hydrothermal</span> and solvothermal methods. First, the definition, history, instrumentation, and mechanism of <span class="hlt">hydrothermal</span> and solvothermal methods as well as the important parameters af-fecting the nucleation and crystal growth of nanomaterials are briefly introduced. Then the specific <span class="hlt">hydrothermal</span> and solvothermal methods used to grow oxides, Group II-VI, III-V, IV, transitional metals, and metal-organic framework nanoparticles are summarized. Finally, the <span class="hlt">hydrothermal</span> and solvothermal strategies used for the surface modification of nanomaterials are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhDT.......396S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhDT.......396S"><span id="translatedtitle">Rational synthesis of multifunctional mixed metal oxides by <span class="hlt">hydrothermal</span> techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stampler, Evan Scott</p> <p></p> <p>Low temperature (<350°C) and pressure (<20 atm) <span class="hlt">hydrothermal</span> methods have been developed for the synthesis of bismuth copper oxide chalcogenides, hexagonal rare-earth manganites, and silver delafossites with mixed cations on the B-<span class="hlt">site</span>. These materials are of particular interest because they combine multiple functional properties, such as transparency and conductivity, or magnetism and ferroelectricity, in a single-phase material, thus enabling innovative technological applications. Phase-pure products were achieved by the appropriate combination of starting reagents, pH, and reaction temperature to control the solubility of the reactants. Phase-pure BiCuOS and BiCuOSe have been synthesized in high yield by a single-step <span class="hlt">hydrothermal</span> reaction at low temperature (250°C) and pressure (< 20 atm). A reaction temperature of 250°C was sufficiently high to solubilize both Bi2O3 ([Bi3+] ≈ 10 -3 M) and Cu2O ([Cu+] ≈ 10-4 M) and stabilize monovalent copper species in solution, yet remains low enough to prevent the oxidation of sulfide and selenide. BiCuOS (Eg = 1.09 eV) and BiCuOSe (Eg = 0.75 eV) have smaller band gaps compared to the p-type transparent conductor LaCuOS (Eg = 3.1 eV) but have significantly higher room temperature conductivities (sigma ≈ 0.08 S cm-1 and 3.3 S cm-1, respectively). The high molar solubility of Mn2O3 ([Mn 3+] ≈ 10-3 M) and the slightly amphoteric character of the late rare-earth sesquioxides were exploited in the <span class="hlt">hydrothermal</span> synthesis of rare-earth manganites, LnMnO3 (Ln=Ho-Lu and Y). While alkaline conditions were necessary for the solubilization of manganese, a reaction temperature approximately 50°C above the transition temperature of the respective rare-earth trihydroxide (100-300°C) accelerated the transition to the more reactive and soluble rare-earth oxide hydroxide and the subsequent reaction to yield the LnMnO3 phase. The high solubility of Ag2O, [Ag+] ≈ 10 -2.5 M, enabled the synthesis of two new silver delafossite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApSS..328..279L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApSS..328..279L"><span id="translatedtitle">Preparation and characterization of nanostructured titanate bioceramic coating by anodization-<span class="hlt">hydrothermal</span> method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Qiannan; Liu, Yong; Lei, Ting; Tan, Yanni; Wu, Hong; Li, Jianbo</p> <p>2015-02-01</p> <p>In this work, nanostructured titanate coatings were prepared on pure titanium substrate by <span class="hlt">hydrothermal</span> treatment combined with and without anodic oxidation. The morphology and microstructure of coatings were characterized and the corrosion resistance and bioactivity were studied. The results show that the anodization-<span class="hlt">hydrothermal</span> method is suitable for the formation of nanostructured titanate coating on Ti in concentrated KOH solution. The coatings are composed of K2Ti6O13 and H2Ti2O5·H2O, and can greatly improve the corrosion resistance of Ti substrate. Moreover, the coatings can induce the formation of new apatite layer after the immersion in simulated body fluid, exhibiting good bioactivity. The anodizaiton treatment can not only accelerate the formation of nanostructures, but also can provide nucleation <span class="hlt">sites</span> for nanostructured titanates, tailoring the morphology of coating. The titanium substrate with nanostructured titanate coating is expected to have significant applications as biomedical materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780013626','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780013626"><span id="translatedtitle">Evaluation of LANDSAT MSS vs TM simulated data for distinguishing <span class="hlt">hydrothermal</span> alteration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abrams, M. J.; Kahle, A. B.; Madura, D. P.; Soha, J. M.</p> <p>1978-01-01</p> <p>The LANDSAT Follow-On (LFO) data was simulated to demonstrate the mineral exploration capability of this system for segregating different types of <span class="hlt">hydrothermal</span> alteration and to compare this capability with that of the existing LANDSAT system. Multispectral data were acquired for several test <span class="hlt">sites</span> with the Bendix 24-channel MSDS scanner. Contrast enhancements, band ratioing, and principal component transformations were used to process the simulated LFO data for analysis. For Red Mountain, Arizona, the LFO data allowed identification of silicified areas, not identifiable with LANDSAT 1 and 2 data. The improved LFO resolution allowed detection of small silicic outcrops and of a narrow silicified dike. For Cuprite - Ralston, Nevada, the LFO spectral bands allowed discrimination of argillic and opalized altered areas; these could not be spectrally discriminated using LANDSAT 1 and 2 data. Addition of data from the 1.3- and 2.2- micrometer regions allowed better discriminations of <span class="hlt">hydrothermal</span> alteration types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830034360&hterms=mars+soil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dmars%2Bsoil','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830034360&hterms=mars+soil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dmars%2Bsoil"><span id="translatedtitle"><span class="hlt">Hydrothermally</span> altered impact melt rock and breccia - Contributions to the soil of Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allen, C. C.; Keil, K.; Gooding, J. L.</p> <p>1982-01-01</p> <p>An examination is made of samples of melt rock and breccia from 12 terrestrial impact craters to identify alteration minerals and their conditions of formation. It is found that in most cases the dominant assemblage is clay-silica-K feldspar-zeolite, suggesting <span class="hlt">hydrothermal</span> alteration at low pressures and temperatures of 100-300 C. The clays are in the main Fe-chlorites and smectites, in most cases depleted in Al and enriched in Fe and Mg relative to their source rocks. The alteration of impact glass is found often to be complete, whereas the alteration of crystalline melt rock is limited to a few percent of the rock volume. Impact breccia is altered to only a slight extent compared with the alteration of glass. It is believed that impact-induced <span class="hlt">hydrothermal</span> alteration is to be expected at Martian impact <span class="hlt">sites</span> if significant quantities of ground ice and/or water are present.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.S22C..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.S22C..02H"><span id="translatedtitle">Remotely Triggered Seismicity in Volcanic and <span class="hlt">Hydrothermal</span> Environments - Which Processes?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hill, D. P.</p> <p>2001-12-01</p> <p>The abrupt increase in seismicity rates at <span class="hlt">sites</span> throughout much of the western United States immediately following the 1992 M=7.4 Landers earthquake provided compelling evidence that large regional earthquakes can trigger local earthquake activity at <span class="hlt">sites</span> many source dimensions removed from the mainshock epicenter. Remotely triggered seismicity has since been documented for a number of other large earthquakes including the 1999 M=7.1 Hector Mine earthquake. Well-documented instances of remotely triggered seismicity are largely confined to transtensional or extensional tectonic regimes with a large fraction of these closely associated with <span class="hlt">hydrothermal</span> and/or young volcanic systems. In the case of Long Valley caldera in eastern California, which responded to both the Landers and Hector Mines earthquakes, the triggered seismicity appears to be secondary to a larger, aseismic deformation transient. Because this is the only remotely triggered <span class="hlt">site</span> with continuous deformation monitoring, however, it remains unclear whether a deformation transient is fundamental component of the remote triggering process. Fluids, either aqueous or magmatic, play a central role in most models for the triggering process in <span class="hlt">hydrothermal</span> and/or young magmatic systems. These models span a range of intriguing (and sometimes counter-intuitive) physical processes including pressure increases associated with advective overpressure and rectified diffusion in bubbly fluids, hydraulic surges resulting from rupturing of compartments of super-hydrostatic fluids in the brittle-plastic transition zone, hydraulic pumping of near-surface pore fluids by surface waves, disruption of fine sediment accumulations (dams) in confined aquifers, local stress changes in the brittle crust associated with relaxation or mobilization of a partially crystallized magma body. All appeal to the dynamic stresses from the mainshock triggering a non-linear response in a crustal volume that is in some sense in a near</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS11D..06G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS11D..06G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Exploration at the Chile Triple Junction - ABE's last adventure?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>German, C. R.; Shank, T. M.; Lilley, M. D.; Lupton, J. E.; Blackman, D. K.; Brown, K. M.; Baumberger, T.; Früh-Green, G.; Greene, R.; Saito, M. A.; Sylva, S.; Nakamura, K.; Stanway, J.; Yoerger, D. R.; Levin, L. A.; Thurber, A. R.; Sellanes, J.; Mella, M.; Muñoz, J.; Diaz-Naveas, J. L.; Inspire Science Team</p> <p>2010-12-01</p> <p>In February and March 2010 we conducted preliminary exploration for <span class="hlt">hydrothermal</span> plume signals along the East Chile Rise where it intersects the continental margin at the Chile Triple Junction (CTJ). This work was conducted as one component of our larger NOAA-OE funded INSPIRE project (Investigation of South Pacific Reducing Environments) aboard RV Melville cruise MV 1003 (PI: Andrew Thurber, Scripps) with all shiptime funded through an award of the State of California to Andrew Thurber and his co-PI's. Additional support came from the Census of Marine Life (ChEss and CoMarge projects). At sea, we conducted a series of CTD-rosette and ABE autonomous underwater vehicle operations to prospect for and determine the nature of any seafloor venting at, or adjacent to, the point where the the East Chile Rise subducts beneath the continental margin. Evidence from in situ sensing (optical backscatter, Eh) and water column analyses of dissolved CH4, δ3He and TDFe/TDMn concentrations document the presence of two discrete <span class="hlt">sites</span> of venting, one right at the triple junction and the other a further 10km along axis, north of the Triple Junction, but still within the southernmost segment of the East Chile Rise. From an intercomparison of the abundance of different chemical signals we can intercompare likely characteristics of these differet source <span class="hlt">sites</span> and also differentiate between them and the high methane concentrations released from cold seep <span class="hlt">sites</span> further north along the Chile Margin, both with the CTJ region and also at the Concepcion Methane Seep Area (CMSA). This multi-disciplinary and international collaboration - involving scientists from Chile, the USA, Europe and Japan - can serve as an excellent and exciting launchpoint for wide-ranging future investigations of the Chile Triple Junction area - the only place on Earth where an oceanic spreading center is being actively subducted beneath a continent and also the only place on Earth where all known forms of deep</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B33A0845G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B33A0845G"><span id="translatedtitle">In Situ Chemical Profiling of an Extremely low Temperature <span class="hlt">Hydrothermal</span> System at Loihi Seamount, Hawaii</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Glazer, B. T.; Briggs, R. A.</p> <p>2007-12-01</p> <p>Loihi Seamount is a submarine, active volcano located on the southeast flanks of the Big Island of Hawaii. It is considered to be the youngest volcano in the chain, sharing the hot spot magma chamber with Mauna Loa and Kilauea. <span class="hlt">Sites</span> of both vigorous and diffuse <span class="hlt">hydrothermal</span> venting can be found surrounding the pit crater summit (1000m) and on the flanks of the seamount, down to its base (5000m). Vent fluids at Loihi are chemically distinct from other well-studied marine <span class="hlt">hydrothermal</span> systems and have been shown to be enriched in carbon dioxide, iron(II), and manganese(II), and deplete in sulfur species. The Loihi summit is located within a zone of low oxygen, further enabling elevated iron(II) concentrations and support for a dominant community of iron-oxidizing bacteria. We deployed a sensor wand consisting of up to four voltammetric working electrodes and the ROV Jason temperature probe, and/or a submersible micromanipulator with voltammetric electrodes to provide real time in situ redox characterizations of <span class="hlt">hydrothermal</span> fluids and geochemical gradients associated with iron-oxidizing microbial mats and flocs. In addition to surveying known areas of warm temperature (10-60 degrees C) venting at the Loihi summit, we performed widespread profiling of a previously undescribed <span class="hlt">site</span> at 5000m, that exhibits temperature anomalies of just 0.2 degrees C. Extensive iron-oxidizing microbial mats were shown to occur up to 2m in thickness over several hundred square meters. Bottom water oxygen concentrations were near-saturation, and we observed steep gradients at the mat-interface, with little oxygen penetration and iron(II) concentrations of up to 150 micromolar. Our in situ electrochemical analyses provided an efficient and valuable means for directed discrete sampling of <span class="hlt">hydrothermal</span> fluids and microbial flocs, as well as previously unattainable high spatial resolution geochemical profiles through the mats.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13A1715S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1715S"><span id="translatedtitle">Biodiversity and biogeography of <span class="hlt">hydrothermal</span> vent species in the western Pacific: a biological perspective of TAIGA project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seo, M.; Watanabe, H.; Nakamura, M.; Sasaki, T.; Ogura, T.; Yahagi, T.; Takahashi, Y.; Ishibashi, J.; Kojima, S.</p> <p>2012-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents are scientifically interesting environments where strong interactions of geology, chemistry, and biology can be observed. The <span class="hlt">hydrothermal</span> vents are geologically controlled in association with magmatic activities while diversity of chemicals (such as hydrogen sulfide) contained in <span class="hlt">hydrothermal</span> fluid is controlled by geochemical interaction between heated seawater and surrounding rocks. In addition to those geological and chemical characters of <span class="hlt">hydrothermal</span> vents, high biomasses of chemosynthetic community have been known around many vents since the first discovery in the 1970s. To understand the unique system and diversity of biological communities associated with vents is highly valuable in geological, chemical, and biological sciences. As an activity of the research project "TAIGA (Trans-crustal Advection & In-situ bio-geochemical processes of Global sub-seafloor Aquifer)" (Representative: Tetsuro Urabe, Department of Earth & Planetary Science, the University of Tokyo), we analyzed population structures and connectivity as well as larval ecology of various <span class="hlt">hydrothermal</span> vent species in the Okinawa Trough and the Mariana Trough in an attempt to estimate faunal transitional history associated with <span class="hlt">hydrothermal</span> activities. The specimens analyzed in the present study were collected by R/V Yokosuka with manned submersible Shinkai6500 and R/V Natsushima with ROV Hyper-Dolphin during YK10-11 and NT11-20 cruises, respectively. In the Mariana Trough (YK10-11), benthic and planktonic faunas were investigated by multiple sampling and use of plankton samplers in three <span class="hlt">hydrothermal</span> vents (Snail, Archaean, and Urashima-Pika fields). Faunal compositions were then compared as well as size compositions and genetic diversities of major vent species among local populations. In the Okinawa Trough (NT11-20), multiple quantitative sampling was made with simultaneous environmental measurements at more than two <span class="hlt">sites</span> in five <span class="hlt">hydrothermal</span> vents (Minami</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5836056','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5836056"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> processes at Mount Rainier, Washington</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frank, D.G.</p> <p>1985-01-01</p> <p>Field studies and thermal-infrared mapping at Mount Rainier indicate areas of active <span class="hlt">hydrothermal</span> alteration where excess surface heat flux is about 9 megawatts. Three representative settings include: (1) An extensive area (greater than 12,000 m/sup 2/) of heated ground and slightly acidic boiling-point fumaroles at 76-82/sup 0/C at East and West Craters on the volcano's summit; (2) A small area (less than 500 m/sup 2/) of heated ground and sub-boiling-point fumaroles at 55-60/sup 0/C on the upper flank at Disappointment Cleaver, and other probably similar areas at Willis Wall, Sunset Amphitheater, and the South Tahoma and Kautz headwalls; (3) Sulfate and carbon dioxide enriched thermal springs at 9-24/sup 0/C on the lower flank of the volcano in valley walls beside the Winthrop and Paradise Glaciers. In addition, chloride- and carbon dioxide-enriched thermal springs issue from thin sediments that overlie Tertiary rocks at, or somewhat beyond, the base of the volcanic edifice in valley bottoms of the Nisqually and Ohanapecosh Rivers where maximum spring temperatures are 19-25/sup 0/C, respectively, and where extensive travertine deposits have developed. The heat flow, distribution of thermal activity, and nature of alteration products indicate that a narrow, central <span class="hlt">hydrothermal</span> system exists within Mount Rainier forming steam-heated snowmelt at the summit craters and localized leakage of steam-heated fluids within 2 kilometers of the summit. The lateral extent of the <span class="hlt">hydrothermal</span> system is limited in that only sparse, neutral sulfate-enriched thermal water issues from the lower flank of the cone. Simulations of geochemical mass transfer suggest that the thermal springs may be derived from an acid sulfate-chloride parent fluid which has been neutralized by reaction with andesite and highly diluted with shallow ground water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1610416B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1610416B"><span id="translatedtitle">Mixing from below in <span class="hlt">hydrothermal</span> ore deposits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bons, Paul D.; Gomez-Rivas, Enrique; Markl, Gregor; Walter, Bejamin</p> <p>2014-05-01</p> <p>Unconformity-related <span class="hlt">hydrothermal</span> ore deposits typically show indications of mixing of two end-member fluids: (a) hot, deep, rock-buffered basement brines and (b) colder fluids derived from the surface or overlying sediments. The hydromechanics of bringing these fluids together from above and below remain unclear. Classical percolative Darcy-flow models are inconsistent with (1) fluid overpressure indicated by fracturing and brecciation, (2) fast fluid flow indicated by thermal disequilibrium, and (3) strong fluid composition variations on the mm-scale, indicated by fluid inclusion analyses (Bons et al. 2012; Fusswinkel et al. 2013). We propose that fluids first descend, sucked down by desiccation reactions in exhumed basement. Oldest fluids reach greatest depths, where long residence times and elevated temperatures allow them the extensively equilibrate with their host rock, reach high salinity and scavenge metals, if present. Youngest fluids can only penetrate to shallower depths and can (partially) retain signatures from their origin, for example high Cl/Br ratios from the dissolution of evaporitic halite horizons. When fluids are released from all levels of the crustal column, these fluids mix during rapid ascent to form <span class="hlt">hydrothermal</span> ore deposits. Mixing from below provides a viable hydromechanical mechanism to explain the common phenomenon of mixed shallow and deep fluids in <span class="hlt">hydrothermal</span> ore deposits. Bons, P.D., Elburg, M.A., Gomez-Rivas, E. 2012. A review of the formation of tectonic veins and their microstructures. J. Struct. Geol. doi:10.1016/j.jsg.2012.07.005 Fusswinkel, T., Wagner, T., Wälle, M., Wenzel, T., Heinrich, C.A., Markl, M. 2013. Fluid mixing forms basement-hosted Pb-Zn deposits: Insight from metal and halogen geochemistry of individual fluid inclusions. Geology. doi:10.1130/G34092.1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22012086','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22012086"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of lutetium disilicate nanoparticles</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tang Xiaoping; Gao Yanfeng; Chen Hongfei; Luo Hongjie</p> <p>2012-04-15</p> <p>A simple, low-cost <span class="hlt">hydrothermal</span> method was developed to synthesize irregular-and rod-shaped lutetium disilicate (Lu{sub 2}Si{sub 2}O{sub 7}) powders with sizes ranging from 71 to 340 nm. The synthesis temperature was 260 Degree-Sign C, which is nearly 1300 Degree-Sign C lower than that required for the solid-state reaction. The results indicated that both the <span class="hlt">hydrothermal</span> temperature and pH values had great influences on the composition, crystalline phase and morphology of the powders. The formation mechanism, basic thermophysical properties, stability and anticorrosion properties of the Lu{sub 2}Si{sub 2}O{sub 7} powders were also investigated. The obtained powders possessed low thermal conductivity, a suitable thermal expansion coefficient (3.92-5.17 Multiplication-Sign 10{sup -6} K{sup -1}) with the silicon-based substrate and excellent thermal and structural stability. During hot corrosion testing, the surfaces of the samples appeared to react with the water and molten salt vapors, but no serious failure occurred. - Graphical abstract: An image for the as-prepared Lu{sub 2}Si{sub 2}O{sub 7} powders (left) and XRD pattern (right) (inset shows the SEM graph of powders). Highlights: Black-Right-Pointing-Pointer We synthesized Lu{sub 2}Si{sub 2}O{sub 7} powders via a <span class="hlt">hydrothermal</span> process at 260 Degree-Sign C. Black-Right-Pointing-Pointer Crystalline phase and morphology of the powders changed with experimental parameter. Black-Right-Pointing-Pointer Hot corrosion was determined in an airflow environment containing alkaline vapor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1224512','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1224512"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Liquefaction Treatment Preliminary Hazard Analysis Report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lowry, Peter P.; Wagner, Katie A.</p> <p>2015-08-31</p> <p>A preliminary hazard assessment was completed during February 2015 to evaluate the conceptual design of the modular <span class="hlt">hydrothermal</span> liquefaction treatment system. The hazard assessment was performed in 2 stages. An initial assessment utilizing Hazard Identification and Preliminary Hazards Analysis (PHA) techniques identified areas with significant or unique hazards (process safety-related hazards) that fall outside of the normal operating envelope of PNNL and warranted additional analysis. The subsequent assessment was based on a qualitative What-If analysis. This analysis was augmented, as necessary, by additional quantitative analysis for scenarios involving a release of hazardous material or energy with the potential for affecting the public.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2236A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2236A"><span id="translatedtitle">Vertical Cable Seismic Survey for <span class="hlt">Hydrothermal</span> Deposit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Ishikawa, K.; Tsukahara, H.; Shimura, T.</p> <p>2012-04-01</p> <p>The vertical cable seismic is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by surface, deep-towed or ocean bottom sources. Analyzing the reflections from the sub-seabed, we could look into the subsurface structure. This type of survey is generally called VCS (Vertical Cable Seismic). Because VCS is an efficient high-resolution 3D seismic survey method for a spatially-bounded area, we proposed the method for the <span class="hlt">hydrothermal</span> deposit survey tool development program that the Ministry of Education, Culture, Sports, Science and Technology (MEXT) started in 2009. We are now developing a VCS system, including not only data acquisition hardware but data processing and analysis technique. Our first experiment of VCS surveys has been carried out in Lake Biwa, JAPAN in November 2009 for a feasibility study. Prestack depth migration is applied to the 3D VCS data to obtain a high quality 3D depth volume. Based on the results from the feasibility study, we have developed two autonomous recording VCS systems. After we carried out a trial experiment in the actual ocean at a water depth of about 400m and we carried out the second VCS survey at Iheya Knoll with a deep-towed source. In this survey, we could establish the procedures for the deployment/recovery of the system and could examine the locations and the fluctuations of the vertical cables at a water depth of around 1000m. The acquired VCS data clearly shows the reflections from the sub-seafloor. Through the experiment, we could confirm that our VCS system works well even in the severe circumstances around the locations of seafloor <span class="hlt">hydrothermal</span> deposits. We have, however, also confirmed that the uncertainty in the locations of the source and of the hydrophones could lower the quality of subsurface image. It is, therefore, strongly necessary to develop a total survey system that assures a accurate positioning and a deployment techniques</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9325H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9325H"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> mineralising systems as critical systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hobbs, Bruce</p> <p>2015-04-01</p> <p><span class="hlt">Hydrothermal</span> mineralising systems as critical systems. Bruce E Hobbs1,2, Alison Ord1 and Mark A. Munro1. 1. Centre for Exploration Targeting, The University of Western Australia, M006, 35 Stirling Highway, Crawley, WA 6009, Australia. 2. CSIRO Earth and Resource Engineering, Bentley, WA, Australia <span class="hlt">Hydrothermal</span> mineralising systems are presented as large, open chemical reactors held far from equilibrium during their life-time by the influx of heat, fluid and dissolved chemical species. As such they are nonlinear dynamical systems and need to be analysed using the tools that have been developed for such systems. <span class="hlt">Hydrothermal</span> systems undergo a number of transitions during their evolution and this paper focuses on methods for characterising these transitions in a quantitative manner and establishing whether they resemble first or second (critical) phase transitions or whether they have some other kind of nature. Critical phase transitions are characterised by long range correlations for some parameter characteristic of the system, power-law probability distributions so that there is no characteristic length scale and a high sensitivity to perturbations; as one approaches criticality, characteristic parameters for the system scale in a power law manner with distance from the critical point. The transitions undergone in mineralised <span class="hlt">hydrothermal</span> systems are: (i) widespread, non-localised mineral alteration involving exothermic mineral reactions that produce hydrous silicate phases, carbonates and iron-oxides, (ii) strongly localised veining, brecciation and/or stock-work formation, (iii) a series of endothermic mineral reactions involving the formation of non-hydrous silicates, sulphides and metals such as gold, (iv) multiple repetitions of transitions (ii) and (iii). We have quantified aspects of these transitions in gold deposits from the Yilgarn craton of Western Australia using wavelet transforms. This technique is convenient and fast. It enables one to establish if</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A53J0284K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A53J0284K"><span id="translatedtitle">The <span class="hlt">Hydrothermal</span> Circulation of the Atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kjellsson, J.; Doos, K.; Laliberté, F. B.; Zika, J. D.</p> <p>2012-12-01</p> <p>The atmospheric circulation maintains the energy balance between the warm/moist regions and the colder/drier regions of the Earth. A well-studied aspect of the atmospheric circulation is the time-averaged zonal-mean meridional overturning circulation. The meridional overturning describes the Hadley, Ferrel and Polar Cells in each hemisphere. However, in isobaric coordinates, the zonal average is unable to capture zonally asymmetric features such as the Walker circulation and transient exchanges of heat and moisture. The Walker Circulation is restricted to equatorial regions, and is commonly studied using a meridional mean over a limited region with ill-defined latitudinal boundaries. The Walker Circulation is thus neither mass-conserving nor uniquely defined. To overtcome these limitations, the Walker circulation is often diagnosed using vertical velocity. As a consequence, it is difficult to distinguish between the zonal-mean circulation (Hadley Circulation) and the zonal asymmetries (Walker Circulation). Global mass and energy transport is here investigated using a moisture-heat perspective. A <span class="hlt">hydrothermal</span> streamfunction is defined where latent heat and dry static energy act as coordinates. Because the <span class="hlt">hydrothermal</span> streamfunction resides in purely thermodynamical space, it does not differentiate between zonal, meridional, or vertical transports. The <span class="hlt">hydrothermal</span> streamfunction shows the global overturning circulation as a unified cycle. It describes a cycle with three branches: i) a convective branch where latent heat is converted into sensible heat along moist adiabats, ii) a cooling branch where dry air loses energy due to radiative damping and iii) a return branch where cold, dry air is heated and moistened following the Clausius-Clapeyron relationship. These three branches form a single cell of more than 400 Sv with at least 100 Sv due to zonal motions such as the Walker Circulation. The cell is also found fairly stationary on seasonal and inter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17014490','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17014490"><span id="translatedtitle">Off-axis symbiosis found: Characterization and biogeography of bacterial symbionts of Bathymodiolus mussels from Lost City <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>DeChaine, Eric G; Bates, Amanda E; Shank, Timothy M; Cavanaugh, Colleen M</p> <p>2006-11-01</p> <p>Organisms at <span class="hlt">hydrothermal</span> vents inhabit discontinuous chemical 'islands' along mid-ocean ridges, a scenario that may promote genetic divergence among populations. The 2003 discovery of mussels at the Lost City <span class="hlt">Hydrothermal</span> Field provided a means of evaluating factors that govern the biogeography of symbiotic bacteria in the deep sea. The unusual chemical composition of vent fluids, the remote location, and paucity of characteristic vent macrofauna at the <span class="hlt">site</span>, raised the question of whether microbial symbioses existed at the extraordinary Lost City. If so, how did symbiotic bacteria therein relate to those hosted by invertebrates at the closest known <span class="hlt">hydrothermal</span> vents along the Mid-Atlantic Ridge (MAR)? To answer these questions, we performed microscopic and molecular analyses on the bacteria found within the gill tissue of Bathymodiolus mussels (Mytilidae, Bathymodiolinae) that were discovered at the Lost City. Here we show that Lost City mussels harbour chemoautotrophic and methanotrophic endosymbionts simultaneously. Furthermore, populations of the chemoautotrophic symbionts from the Lost City and two <span class="hlt">sites</span> along the MAR are genetically distinct from each other, which suggests spatial isolation of bacteria in the deep sea. These findings provide new insights into the processes that drive diversification of bacteria and evolution of symbioses at <span class="hlt">hydrothermal</span> vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017098','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017098"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil <span class="hlt">Hydrothermal</span> Field</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ridley, W.I.; Perfit, M.R.; Josnasson, I.R.; Smith, M.F.</p> <p>1994-01-01</p> <p>The Galapagos Fossil <span class="hlt">Hydrothermal</span> Field is composed of altered oceanic crust and extinct <span class="hlt">hydrothermal</span> vents within the eastern Galapagos Rift between 85??49???W and 85??55???W. The discharge zone of the <span class="hlt">hydrothermal</span> system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the <span class="hlt">hydrothermal</span> alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens' equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (< 10) conditions following a period of lower-temperature weathering of volcanics within the rift zone. The complex patterns of element enrichment and depletion and strontium isotope variations indicate mixing between pristine seawater and ascending hot fluids to produce a compositional spectrum of fluids. The precipitation of base-metal sulfides beneath the seafloor is probably a result of fluid mixing and cooling. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine <span class="hlt">hydrothermal</span> systems</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GGG.....8.6010G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GGG.....8.6010G"><span id="translatedtitle">Geology and <span class="hlt">hydrothermal</span> evolution of the Mothra <span class="hlt">Hydrothermal</span> Field, Endeavour Segment, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Glickson, Deborah A.; Kelley, Deborah S.; Delaney, John R.</p> <p>2007-06-01</p> <p>Detailed characterization of the Mothra <span class="hlt">Hydrothermal</span> Field, the most southern and spatially extensive field on the Endeavour Segment of the Juan de Fuca Ridge, provides new insights into its geologic and <span class="hlt">hydrothermal</span> development. Meter-scale bathymetry, side-scan sonar imagery, and direct dive observations show that Mothra is composed of six actively venting sulfide clusters spaced 40-200 m apart. Chimneys within each cluster have similar morphology and venting characteristics, and all clusters host a combination of active and extinct sulfide structures. Black smoker chimneys venting fluids above 300°C are rare, while more common lower-temperature, diffusely venting chimneys support dense colonies of macrofauna and bacterial mat. <span class="hlt">Hydrothermal</span> sediment and extinct sulfide debris cover 10-15 m of the seafloor surrounding each vent cluster, obscuring the underlying basaltic substrate of light to moderately sedimented pillow, lobate, sheet, and chaotic flows, basalt talus, and collapse terrain. Extinct sulfide chimneys and debris between the clusters indicate that <span class="hlt">hydrothermal</span> flow was once more widespread and that it has shifted spatially over time. The most prominent structural features in the axial valley at Mothra are regional (020°) trending faults and fissures and north-south trending collapse basins. The location of actively venting clusters within the field is controlled by (1) localization of fluid upflow along the western boundary fault zone, and diversion of these fluids by antithetic faults to feed vent clusters near the western valley wall, and (2) tapping of residual magmatic heat in the central part of the axial valley, which drives flow beneath vent clusters directly adjacent to the collapse basins 70-90 m east of the western valley wall. These processes form the basis for a model of axial valley and <span class="hlt">hydrothermal</span> system development at Mothra, in which the field is initiated by an eruptive-diking episode and sustained through intense microseismicity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/482169','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/482169"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil <span class="hlt">Hydrothermal</span> Field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ridley, W.I.; Perfit, M.R.; Smith, M.F.; Jonasson, I.R.</p> <p>1994-06-01</p> <p>The Galapagos Fossil <span class="hlt">Hydrothermal</span> Field is composed of altered oceanic crust and extinct <span class="hlt">hydrothermal</span> vents within the eastern Galapagos Rift between 85{degree}49 feet W and 85{degree} 55 feet W. The discharge zone of the <span class="hlt">hydrothermal</span> system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the <span class="hlt">hydrothermal</span> alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens` equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (<10) conditions following a period of lower-temperature weathering of volcanics within the rift zone. The complex patterns of element enrichment and depletion and strontium isotope variations indicate mixing between pristine seawater and ascending hot fluids to produce a compositional spectrum of fluids. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine <span class="hlt">hydrothermal</span> systems. 50 refs., 10 figs., 4 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2033H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2033H"><span id="translatedtitle">Iron-Oxidizing Bacteria Found at Slow-Spreading Ridge: a Case Study of Capelinhos <span class="hlt">Hydrothermal</span> Vent (Lucky Strike, MAR 37°N)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henri, P. A.; Rommevaux, C.; Lesongeur, F.; Emerson, D.; Leleu, T.; Chavagnac, V.</p> <p>2015-12-01</p> <p>Iron-oxidizing bacteria becomes increasingly described in different geological settings from volcanically active seamounts, coastal waters, to diffuse <span class="hlt">hydrothermal</span> vents near seafloor spreading centers [Emerson et al., 2010]. They have been mostly identified and described in Pacific Ocean, and have been only recently found in <span class="hlt">hydrothermal</span> systems associated to slow spreading center of the Mid-Atlantic Ridge (MAR) [Scott et al., 2015]. During the MoMARSAT'13 cruise at Lucky Strike <span class="hlt">hydrothermal</span> field (MAR), a new <span class="hlt">hydrothermal</span> <span class="hlt">site</span> was discovered at about 1.5 km eastward from the lava lake and from the main <span class="hlt">hydrothermal</span> vents. This active venting <span class="hlt">site</span>, named Capelinhos, is therefore the most distant from the volcano, features many chimneys, both focused and diffuses. The <span class="hlt">hydrothermal</span> end-member fluids from Capelinhos are different from those of the other <span class="hlt">sites</span> of Lucky Strike, showing the highest content of iron (Fe/Mn≈3.96) and the lowest chlorinity (270 mmol/l) [Leleu et al., 2015]. Most of the chimneys exhibit rust-color surfaces and bacterial mats near diffuse flows. During the MoMARSAT'15 cruise, an active chimney, a small inactive one, and rust-color bacterial mat near diffuse flow were sampled at Capelinhos. Observations by SEM of the <span class="hlt">hydrothermal</span> samples revealed the presence of iron oxides in an assemblage of tubular "sheaths", assembled "stalks", helical "stalks" and amorphous aggregates. These features are similar to those described from the Loihi iron-mats deposits and argue for the occurrence of iron-oxidizing bacteria. Cultures under micro-aerobic and neutral pH conditions allowed us to isolate strains from the small inactive chimney. Pyrosequencing of the 16S rRNA gene of the isolates and environmental samples will soon be performed, which should confirm the presence of iron-oxidizing bacteria and reveal the organization of bacterial communities in this original and newly discovered <span class="hlt">hydrothermal</span> <span class="hlt">site</span> of the slow spreading Mid-Atlantic Ridge. Emerson</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMOS11B1477M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMOS11B1477M"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Fluxes at the Mid-Atlantic Ridge, 5°S</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mertens, C.; Walter, M.; Koehler, J.; Sueltenfuss, J.; Rhein, M.</p> <p>2011-12-01</p> <p>The growing number of known <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> has lead to an increasing recognition of the quantitative importance of <span class="hlt">hydrothermally</span> derived materials in the large scale ocean circulation due to their possible impact on the ocean carbon cycle. The basin wide spreading of primordial helium measured during the WOCE era revealed intense <span class="hlt">hydrothermal</span> venting in the South Atlantic, but it was not until 2005 that the first vent fields were located after intense surveys along the Mid-Atlantic Ridge. Before these sur- veys no <span class="hlt">hydrothermal</span> fields were known in the Atlantic between 12°N and the Southern Ocean, thus leaving a large gap in the biogeography of <span class="hlt">hydrothermal</span> vent fauna. One of the newly discovered <span class="hlt">sites</span> is located in a relatively short segment of the rift valley at 5°S. It consists of three known high temperature fields: Turtle Pits, Comfortless Cove, and Red Lion, as well as several areas were diffuse venting was found. Hydrographic measurements were carried out at the Turtle Pits vent <span class="hlt">site</span> during three cruises: Meteor cruise 68/1 in May 2006, a cruise with the french vessel L'Atalante in January 2008, and Meteor cruise 78/2 in April/May 2009. The data collected during these cruises are vertical profiles and towed sections of temperature, salinity, and turbidity, direct velocity measurements with lowered acoustic Doppler current profilers, as well as water samples for Helium isotope analysis. The hydrography at the vent <span class="hlt">sites</span> is largely determined by the location of the <span class="hlt">sites</span> in relation to the surrounding rift valley. The vents are situated in the center of the valley at a topographic sill. The water column plumes of the vent fields are clearly visible by strong signals in turbidity and temperature anomalies, and show a maximum rise height of more than 200 m, which does not exceed the height of the side walls of the graben. The currents in the rift valley are predominantly northward; the difference in stratification between upstream and downstream</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.P31G..09N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P31G..09N"><span id="translatedtitle">Lessons from studies of impact crater <span class="hlt">hydrothermal</span> processes in terrestrial analogs and their implications for impact craters on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newsom, H. E.</p> <p>2011-12-01</p> <p>Studying <span class="hlt">hydrothermal</span> processes in terrestrial impact craters as martian analogs has sometimes been fraught with objections, including the Earth's greater abundance of water, the neutral instead of acidic aqueous environments and the composition of the targets. Although recent discoveries have dispelled many objections, some misconceptions remain. For example, the relevance of the Chicxulub crater as a martian analog is sometimes questioned because the target was covered with sediments, including carbonates and sulfates. However the impactites at the Yaxcopoil-1 drill <span class="hlt">site</span> are derived from the underlying silicate basement. Comparisons can also be difficult because of scale issues, as many terrestrial craters with evidence of <span class="hlt">hydrothermal</span> activity, e.g. Lonar, Haughton, Ries etc., are smaller than the Martian craters with phyllosilicate signatures (Ehlmann et al., 2010). Summarizing, the results of many studies of terrestrial craters show that: 1) Most terrestrial craters larger than 1.8 km diameter have at least some evidence of aqueous or <span class="hlt">hydrothermal</span> processes in the form of alteration minerals (e.g., Naumov, 2005). 2) Impact melts in crater fill and ejecta blankets provide heat that can produce <span class="hlt">hydrothermal</span> alteration if water is available (Newsom, 1980). 3) The uplifted geothermal gradient can be as important a heat source as shock effects. 4) Mineralogical evidence for high-temperature fluids (> 350 oC) is present in the central uplift of the Manson structure, and in the ejecta from the Chicxulub impact, where precipitation of phyllosilicates from <span class="hlt">hydrothermal</span> fluids has also been described (Newsom et al., 2010). 5) Impact deposits begin hot, but have an extended cooling period during which alteration phases can back react to low temperature phases with corresponding stable isotope signatures. 5) <span class="hlt">Hydrothermal</span> fluids can travel long distances from their sources (e.g., Chicxulub, Yaxcopoil <span class="hlt">site</span>) and are often localized to faults or porous breccias (e.g. Sudbury</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.sciencedirect.com/science/article/pii/S0016703710006344','USGSPUBS'); return false;" href="http://www.sciencedirect.com/science/article/pii/S0016703710006344"><span id="translatedtitle">Geochemistry of <span class="hlt">hydrothermal</span> fluids from the PACMANUS, Northeast Pual and Vienna Woods <span class="hlt">hydrothermal</span> fields, Manus Basin, Papua New Guinea</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reeves, Eoghan P.; Seewald, Jeffrey S.; Saccocia, Peter; Bach, Wolfgang; Craddock, Paul R.; Shanks, Wayne C.; Sylva, Sean P.; Walsh, Emily; Pichler, Thomas; Rosner, Martin</p> <p>2011-01-01</p> <p>Processes controlling the composition of seafloor <span class="hlt">hydrothermal</span> fluids in silicic back-arc or near-arc crustal settings remain poorly constrained despite growing evidence for extensive magmatic-<span class="hlt">hydrothermal</span> activity in such environments. We conducted a survey of vent fluid compositions from two contrasting <span class="hlt">sites</span> in the Manus back-arc basin, Papua New Guinea, to examine the influence of variations in host rock composition and magmatic inputs (both a function of arc proximity) on <span class="hlt">hydrothermal</span> fluid chemistry. Fluid samples were collected from felsic-hosted <span class="hlt">hydrothermal</span> vent fields located on Pual Ridge (PACMANUS and Northeast (NE) Pual) near the active New Britain Arc and a basalt-hosted vent field (Vienna Woods) located farther from the arc on the Manus Spreading Center. Vienna Woods fluids were characterized by relatively uniform endmember temperatures (273-285 degrees C) and major element compositions, low dissolved CO2 concentrations (4.4 mmol/kg) and high measured pH (4.2-4.9 at 25 degrees C). Temperatures and compositions were highly variable at PACMANUS/NE Pual and a large, newly discovered vent area (Fenway) was observed to be vigorously venting boiling (358 degrees C) fluid. All PACMANUS fluids are characterized by negative delta DH2O values, in contrast to positive values at Vienna Woods, suggesting substantial magmatic water input to circulating fluids at Pual Ridge. Low measured pH (25 degrees C) values (~2.6-2.7), high endmember CO2 (up to 274 mmol/kg) and negative delta 34SH2S values (down to -2.7 permille) in some vent fluids are also consistent with degassing of acid-volatile species from evolved magma. Dissolved CO2 at PACMANUS is more enriched in 13C (-4.1 permille to -2.3 permille) than Vienna Woods (-5.2 permille to -5.7 permille), suggesting a contribution of slab-derived carbon. The mobile elements (e.g. Li, K, Rb, Cs and B) are also greatly enriched in PACMANUS fluids reflecting increased abundances in the crust there relative to the Manus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B13C0512M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B13C0512M"><span id="translatedtitle">High-pressure hydrogen respiration in <span class="hlt">hydrothermal</span> vent samples from the deep biosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morgan-Smith, D.; Schrenk, M. O.</p> <p>2013-12-01</p> <p>Cultivation of organisms from the deep biosphere has met with many challenges, chief among them the ability to replicate this extreme environment in a laboratory setting. The maintenance of in situ pressure levels, carbon sources, and gas concentrations are important, intertwined factors which may all affect the growth of subsurface microorganisms. Hydrogen in particular is of great importance in <span class="hlt">hydrothermal</span> systems, but in situ hydrogen concentrations are largely disregarded in attempts to culture from these <span class="hlt">sites</span>. Using modified Hungate-type culture tubes (Bowles et al. 2011) within pressure-retaining vessels, which allow for the dissolution of higher concentrations of gas than is possible with other culturing methods, we have incubated <span class="hlt">hydrothermal</span> chimney and <span class="hlt">hydrothermally</span>-altered rock samples from the Lost City and Mid-Cayman Rise <span class="hlt">hydrothermal</span> vent fields. Hydrogen concentrations up to 15 mmol/kg have been reported from Lost City (Kelley et al. 2005), but data are not yet available from the recently-discovered Mid-Cayman <span class="hlt">site</span>, and the elevated concentration of 30 mmol/kg is being used in all incubations. We are using a variety of media types to enrich for various metabolic pathways including iron and sulfur reduction under anoxic or microaerophilic conditions. Incubations are being carried out at atmospheric (0.1 MPa), in situ (9, 23, or 50 MPa, depending on <span class="hlt">site</span>), and elevated (50 MPa) pressure levels. Microbial cell concentrations, taxonomic diversity, and metabolic activities are being monitored during the course of these experiments. These experiments will provide insight into the relationships between microbial activities, pressure, and gas concentrations typical of deep biosphere environments. Results will inform further culturing studies from both fresh and archived samples. References cited: Bowles, M.W., Samarkin, V.A., Joye, S.B. 2011. Improved measurement of microbial activity in deep-sea sediments at in situ pressure and methane concentration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9243009','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9243009"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems as environments for the emergence of life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shock, E L</p> <p>1996-01-01</p> <p>Analysis of the chemical disequilibrium provided by the mixing of <span class="hlt">hydrothermal</span> fluids and seawater in present-day systems indicates that organic synthesis from CO2 or carbonic acid is thermodynamically favoured in the conditions in which hyperthermophilic microorganisms are known to live. These organisms lower the Gibbs free energy of the chemical mixture by synthesizing many of the components of their cells. Primary productivity is enormous in <span class="hlt">hydrothermal</span> systems because it depends only on catalysis of thermodynamically favourable, exergonic reactions. It follows that <span class="hlt">hydrothermal</span> systems may be the most favourable environments for life on Earth. This fact makes <span class="hlt">hydrothermal</span> systems logical candidates for the location of the emergence of life, a speculation that is supported by genetic evidence that modern hyperthermophilic organisms are closer to a common ancestor than any other forms of life. The presence of <span class="hlt">hydrothermal</span> systems on the early Earth would correspond to the presence of liquid water. Evidence that <span class="hlt">hydrothermal</span> systems existed early in the history of Mars raises the possibility that life may have emerged on Mars as well. Redox reactions between water and rock establish the potential for organic synthesis in and around <span class="hlt">hydrothermal</span> systems. Therefore, the single most important parameter for modelling the geochemical emergence of life on the early Earth or Mars is the composition of the rock which hosts the <span class="hlt">hydrothermal</span> system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040173291&hterms=genetic+environment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dgenetic%2Benvironment','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040173291&hterms=genetic+environment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dgenetic%2Benvironment"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems as environments for the emergence of life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, E. L.</p> <p>1996-01-01</p> <p>Analysis of the chemical disequilibrium provided by the mixing of <span class="hlt">hydrothermal</span> fluids and seawater in present-day systems indicates that organic synthesis from CO2 or carbonic acid is thermodynamically favoured in the conditions in which hyperthermophilic microorganisms are known to live. These organisms lower the Gibbs free energy of the chemical mixture by synthesizing many of the components of their cells. Primary productivity is enormous in <span class="hlt">hydrothermal</span> systems because it depends only on catalysis of thermodynamically favourable, exergonic reactions. It follows that <span class="hlt">hydrothermal</span> systems may be the most favourable environments for life on Earth. This fact makes <span class="hlt">hydrothermal</span> systems logical candidates for the location of the emergence of life, a speculation that is supported by genetic evidence that modern hyperthermophilic organisms are closer to a common ancestor than any other forms of life. The presence of <span class="hlt">hydrothermal</span> systems on the early Earth would correspond to the presence of liquid water. Evidence that <span class="hlt">hydrothermal</span> systems existed early in the history of Mars raises the possibility that life may have emerged on Mars as well. Redox reactions between water and rock establish the potential for organic synthesis in and around <span class="hlt">hydrothermal</span> systems. Therefore, the single most important parameter for modelling the geochemical emergence of life on the early Earth or Mars is the composition of the rock which hosts the <span class="hlt">hydrothermal</span> system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://dx.doi.org/10.1016/j.jvolgeores.2015.07.025','USGSPUBS'); return false;" href="http://dx.doi.org/10.1016/j.jvolgeores.2015.07.025"><span id="translatedtitle">Integrated thermal infrared imaging and Structure-from-Motion photogrametry to map apparent temperature and radiant <span class="hlt">hydrothermal</span> heat flux at Mammoth Mountain, CA USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Aaron Lewis,; George Hilley,; Lewicki, Jennifer L.</p> <p>2015-01-01</p> <p>This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant <span class="hlt">hydrothermal</span> heat flux and estimate the radiant <span class="hlt">hydrothermal</span> heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more <span class="hlt">sites</span> within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the Structure-from-Motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant <span class="hlt">hydrothermal</span> heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant <span class="hlt">hydrothermal</span> heat fluxes were observed up to 73.7 oC and 450 W m-2, respectively, while the estimated radiant <span class="hlt">hydrothermal</span> heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating <span class="hlt">hydrothermal</span> heat-related hazards on the volcano.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.V21A4729T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.V21A4729T&link_type=ABSTRACT"><span id="translatedtitle">Constraints on the Lost City <span class="hlt">Hydrothermal</span> System from borehole thermal data; 3-D models of heat flow and <span class="hlt">hydrothermal</span> circulation in an oceanic core complex.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Titarenko, S.; McCaig, A. M.</p> <p>2014-12-01</p> <p>A perennial problem in near-ridge <span class="hlt">hydrothermal</span> circulation is that the only directly measurable data to test models is often vent fluid temperature. Surface heat flow measurements may be available but without the underlying thermal structure it is not known if they are transient and affected by local <span class="hlt">hydrothermal</span> flow, or conductive. The Atlantis Massif oceanic core complex at 30 °N on the mid-Atlantic Ridge, offers a unique opportunity to better constrain <span class="hlt">hydrothermal</span> circulation models. The temperature profile in gabbroic rocks of IODP Hole 1309D was measured in IODPExpedition 340T, and found to be near-conductive, but with a slight inflexion at ~750 mbsf indicating downward advection of fluid above that level. The lack of deep convection is especially remarkable given that the long-lived Lost City <span class="hlt">Hydrothermal</span> Field (LCHF) is located only 5km to the south. We have modelled <span class="hlt">hydrothermal</span> circulation in the Massif using Comsol Multiphysics, comparing 2-D and 3-D topographic models and using temperature-dependent conductivity to give the best estimate of heatflow into the Massif. We can constrain maximum permeability in gabbro below 750 mbsf to 5e-17 m2. The thermal gradient in the upper part of the borehole can be matched with a permeability of 3e-14 m2 in a 750 m thick layer parallel to the surface of the massif, with upflow occurring in areas of high topography and downflow at the location of the borehole. However in 3-D the precise flow pattern is quite model dependent, and the thermal structure can be matched either by downflow centred on the borehole at lower permeability or centred a few hundred metres from the borehole at higher permeability. The borehole gradient is compatible with the longevity (>120 kyr) and outflow temperature (40-90 °C) of the LCHF either with a deep more permeable (1e-14 m2 to 1e-15 m2) domain beneath the vent <span class="hlt">site</span> in 2-D or a permeable fault slot 500 to 1000m wide and parallel to the transform fault in 3-D. In both cases topography</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS22C..04F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS22C..04F"><span id="translatedtitle">Shallow Water <span class="hlt">Hydrothermal</span> Vents in the Gulf of California: Natural Laboratories for Multidisciplinary Research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Forrest, M.; Hilton, D. R.; Price, R. E.; Kulongoski, J. T.</p> <p>2015-12-01</p> <p>Modern and fossil examples of shallow water submarine <span class="hlt">hydrothermal</span> vents occur throughout the Gulf of California. These <span class="hlt">sites</span> offer important information about the processes involved in the extensional tectonics that created the Gulf of California and continue to shape the region to this day. Due to their accessibility, shallow water marine <span class="hlt">hydrothermal</span> vents are far easier to access and study than their deeper analogs, and these settings can provide natural laboratories to study biogeochemical processes. Certain biogeochemical and biomineralizing processes occurring at shallow vents are very similar to those observed around deep-sea <span class="hlt">hydrothermal</span> vents. In some cases, authigenic carbonates form around shallow vents. However, the <span class="hlt">hydrothermal</span> precipitates are generally composed of Fe-oxyhydroxides, Mn-oxides, opal, calcite, pyrite and cinnabar, and their textural and morphological characteristics suggest microbial mediation for mineral deposition. Modern shallow-water <span class="hlt">hydrothermal</span> vents also support complex biotic communities, characterized by the coexistence of chemosynthetic and photosynthetic organisms. These shallow vents are highly productive and provide valuable resources to local fishermen. Extant shallow water <span class="hlt">hydrothermal</span> activity has been studied in Bahía Concepción, San Felipe, Punta Estrella, El Coloradito, Puertecitos, and around the Islas Encantadas. Discrete streams of gas bubbles are often discharged along with hot liquids at shallow water vents. The vent liquids generally exhibit lower salinities than seawater, and their isotopic compositions indicate that they contain meteoric water mixed with seawater. The composition of the shallow vent gas is primarily made up of CO2, but may also be enriched in N2, H2S, CH4, and other higher hydrocarbons. The geochemistry of these gases can be informative in determining the sources and processes involved in their generation. In particular, 3He/4He ratios may provide valuable information about the origin of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5815304','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5815304"><span id="translatedtitle">Ecology of deep-sea <span class="hlt">hydrothermal</span> vent communities: A review</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lutz, R.A.; Kennish, M.J. )</p> <p>1993-08-01</p> <p>The present article reviews studies of the past 15 years of active and inactive <span class="hlt">hydrothermal</span> vents. The focus of the discussion is on the ecology of the biological communities inhabiting <span class="hlt">hydrothermal</span> vents. These communities exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. The authors attempt to relate the biology of <span class="hlt">hydrothermal</span> vent systems to geology. Future directions for <span class="hlt">hydrothermal</span> vent research are suggested. Since many vent populations are dependent on <span class="hlt">hydrothermal</span> fluids and are consequently unstable, both short- and long-term aspects of the ecology of the vent organisms and the influence of chemical and geological factors on the biology of vent systems need to be established. 200 refs., 28 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24709539','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24709539"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> carbonization and torrefaction of grape pomace: a comparative evaluation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pala, Mehmet; Kantarli, Ismail Cem; Buyukisik, Hasan Baha; Yanik, Jale</p> <p>2014-06-01</p> <p>Grape pomace was treated by <span class="hlt">hydrothermal</span> carbonization (sub-critical water, 175-275°C) and torrefaction (nitrogen atmosphere, 250 and 300°C), with mass yield of solid product (char) ranging between 47% and 78%, and energy densification ratio to 1.42-1.15 of the original feedstock. The chars were characterised with respect to their fuel properties, morphological and structural properties and combustion characteristics. The <span class="hlt">hydrothermal</span> carbonization produced the char with greater energy density than torrefaction. The chars from torrefaction were found to be more aromatic in nature than that from <span class="hlt">hydrothermal</span> carbonization. <span class="hlt">Hydrothermal</span> carbonization process produced the char having high combustion reactivity. Most interesting was the finding that aqueous phase from <span class="hlt">hydrothermal</span> carbonization had antioxidant activity. The results obtained in this study showed that HTC appears to be promising process for a winery waste having high moisture content.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3751430','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3751430"><span id="translatedtitle">The fate of lignin during <span class="hlt">hydrothermal</span> pretreatment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>Background Effective enzymatic hydrolysis of lignocellulosic biomass benefits from lignin removal, relocation, and/or modification during <span class="hlt">hydrothermal</span> pretreatment. Phase transition, depolymerization/repolymerization, and solubility effects may all influence these lignin changes. To better understand how lignin is altered, Populus trichocarpa x P. deltoides wood samples and cellulolytic enzyme lignin (CEL) isolated from P. trichocarpa x P. deltoides were subjected to batch and flowthrough pretreatments. The residual solids and liquid hydrolysate were characterized by gel permeation chromatography, heteronuclear single quantum coherence NMR, compositional analysis, and gas chromatography–mass spectrometry. Results Changes in the structure of the solids recovered after the pretreatment of CEL and the production of aromatic monomers point strongly to depolymerization and condensation being primary mechanisms for lignin extraction and redeposition. The differences in lignin removal and phenolic compound production from native P. trichocarpa x P. deltoides and CEL suggested that lignin-carbohydrate interactions increased lignin extraction and the extractability of syringyl groups relative to guaiacyl groups. Conclusions These insights into delignification during <span class="hlt">hydrothermal</span> pretreatment point to desirable pretreatment strategies and plant modifications. Because depolymerization followed by repolymerization appears to be the dominant mode of lignin modification, limiting the residence time of depolymerized lignin moieties in the bulk liquid phase should reduce lignin content in pretreated biomass. In addition, the increase in lignin removal in the presence of polysaccharides suggests that increasing lignin-carbohydrate cross-links in biomass would increase delignification during pretreatment. PMID:23902789</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JSSCh.188...38T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSSCh.188...38T"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of lutetium disilicate nanoparticles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tang, Xiaoping; Gao, Yanfeng; Chen, Hongfei; Luo, Hongjie</p> <p>2012-04-01</p> <p>A simple, low-cost <span class="hlt">hydrothermal</span> method was developed to synthesize irregular-and rod-shaped lutetium disilicate (Lu2Si2O7) powders with sizes ranging from 71 to 340 nm. The synthesis temperature was 260 °C, which is nearly 1300 °C lower than that required for the solid-state reaction. The results indicated that both the <span class="hlt">hydrothermal</span> temperature and pH values had great influences on the composition, crystalline phase and morphology of the powders. The formation mechanism, basic thermophysical properties, stability and anticorrosion properties of the Lu2Si2O7 powders were also investigated. The obtained powders possessed low thermal conductivity, a suitable thermal expansion coefficient (3.92-5.17×10-6 K-1) with the silicon-based substrate and excellent thermal and structural stability. During hot corrosion testing, the surfaces of the samples appeared to react with the water and molten salt vapors, but no serious failure occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990PrOce..24...71L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990PrOce..24...71L"><span id="translatedtitle">Nutritional strategies of the <span class="hlt">hydrothermal</span> ecosystem bivalves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pennec, Marcel; Donval, Anne; Herry, Angèle</p> <p></p> <p>Studies of deep-sea <span class="hlt">hydrothermal</span> bivalves have revealed that the species, which are strictly dependent upon the interstitial fluid emissions, derive their food indirectly via symbiotic relationships with chemosynthetic bacteria present in their gill tissues. As the gill plays the main trophic role, structural and ultrastructural modifications occur in the digestive tract. Scanning and transmission electron microscope studies reveal that the digestive system of species belonging to the genera Calyptogena, Bathymodiolus and Bathypecten have anatomical differences. In Calyptogena, the reduction of several parts of the digestive tract and the stomach content which is either empty or full, according to the various species examined indicate that the digestive system is hardly if at all functional. In Bathymodiolus, the labial palps are well developed, the stomach is always full with particles and the two cellular types, digestive and secretory, are present in the digestive gland. All these characteristics indicate that the digestive system is functional. In Bathypecten, the digestive tract is well developed and it seems that it plays the main trophic role. We conclude that the nutritional strategies of the <span class="hlt">hydrothermal</span> vents bivalves are quite varied. They range from a normal trophic process, through a mixotrophic diet, to one based purely on chemoautotrophic bacteria. The strategy of each species is adapted to and influences its distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19050821','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19050821"><span id="translatedtitle">Bacterial and archaeal populations at two shallow <span class="hlt">hydrothermal</span> vents off Panarea Island (Eolian Islands, Italy).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maugeri, Teresa Luciana; Lentini, Valeria; Gugliandolo, Concetta; Italiano, Francesco; Cousin, Sylvie; Stackebrandt, Erko</p> <p>2009-01-01</p> <p>The aim of this study was to investigate the microbial community thriving at two shallow <span class="hlt">hydrothermal</span> vents off Panarea Island (Italy). Physico-chemical characteristics of thermal waters were examined in order to establish the effect of the vents on biodiversity of both Bacteria and Archaea. Water and adjacent sediment samples were collected at different times from two vents, characterised by different depth and temperature, and analysed to evaluate total microbial abundances, sulphur-oxidising and thermophilic aerobic bacteria. Total microbial abundances were on average of the order of 10(5) cells ml(-1), expressed as picoplanktonic size fraction. Picophytoplanktonic cells accounted for 0.77-3.83% of the total picoplanktonic cells. The contribution of bacterial and archaeal taxa to prokaryotic community diversity was investigated by PCR-DGGE fingerprinting method. The number of bands derived from bacterial DNA was highest in the DGGE profiles of water sample from the warmest and deepest <span class="hlt">site</span> (<span class="hlt">site</span> 2). In contrast, archaeal richness was highest in the water of the coldest and shallowest <span class="hlt">site</span> (<span class="hlt">site</span> 1). Sulphur-oxidising bacteria were detected by both culture-dependent and -independent methods. The primary production at the shallow <span class="hlt">hydrothermal</span> system of Panarea is supported by a complex microbial community composed by phototrophs and chemolithotrophs. PMID:19050821</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24391244','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24391244"><span id="translatedtitle">Vacuolate-attached filaments: highly productive Ridgeia piscesae epibionts at the Juan de Fuca <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kalanetra, Karen M; Nelson, Douglas C</p> <p>2010-01-01</p> <p>Vacuolate sulfur bacteria with high morphological similarity to vacuolate-attached filaments previously described from shallow <span class="hlt">hydrothermal</span> vents (White Point, CA) were found at deep-sea <span class="hlt">hydrothermal</span> vents. These filamentous bacteria grow in dense mats that cover surfaces and potentially provide a significant source of organic carbon where they occur. Vacuolate-attached filaments were collected near vents at the Clam Bed <span class="hlt">site</span> of the Endeavour Segment of the Juan de Fuca Ridge and from the sediment surface at Escanaba Trough on the Gorda Ridge. A phylogenetic analysis comparing their 16S rRNA gene sequences to those collected from the shallow White Point <span class="hlt">site</span> showed that all vacuolate-attached filament sequences form a monophyletic group within the vacuolate sulfur-oxidizing bacteria clade in the gamma proteobacteria. Abundance of the attached filaments was quantified over the length of the exterior surface of the tubes of Ridgeia piscesae worms collected from the Clam Bed <span class="hlt">site</span> at Juan de Fuca yielding a per worm average of 0.070 ± 0.018 cm(3) (n = 4). In agreement with previous results for White Point filaments, anion measurements by ion chromatography showed no detectable internal nitrate concentrations above ambient seawater (n = 9). For one R. piscesae tube worm "bush" at the Easter Island vent <span class="hlt">site</span>, potential gross epibiont productivity is estimated to be 15 to 45× the net productivity of the worms. PMID:24391244</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1610934T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1610934T"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> circulation in fault slots with topography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Titarenko, Sofya; McCaig, Andrew</p> <p>2014-05-01</p> <p>There are numerous cases where the circulation of <span class="hlt">hydrothermal</span> fluid is likely to be confined within a permeable fault slot. Examples are (1) the Lost City <span class="hlt">Hydrothermal</span> Field (LCHF) at 30 N in the Atlantic, which is likely to be controlled by large E-W faults related to the Atlantis transform fault and mass wasting on the southern wall of the Atlantis Massif, and (2) large normal faults bounding the Hess Deep rift in the East Pacific, which contain intense <span class="hlt">hydrothermal</span> metamorphic assemblages in lower crustal gabbros formed at 200-350 ° C. This type of circulation could occur anywhere where steep faults cut the oceanic crust, including large near-axis normal faults, transform faults and faults at subduction bend zones, and could be the major way in which the upper mantle and lower crust are hydrated. It is therefore important to constrain the controls on temperature conditions of alteration and hence mineral assemblages. Previous 2-D modelling of the LCHF shows that seafloor topography and permeability structure combine together to localise the field near the highest point of the Atlantis Massif. Our new models are 3-D, based on a 10km cube with seafloor topography of ~ 2km affecting both the fault slot and impermeable wall rocks. We have used Comsol multiphysics in this modelling, with a constant basal heatflow corresponding to the near conductive thermal gradient measured in IODP Hole 1309D, 5km north of the LCHF, and a constant temperature seafloor boundary condition. The wall rocks of the slot have a permeability of 10-17 m2 while permeability in the slot is varied between 10-14 and 10-15 m2. Initial conditions are a conductive thermal structure corresponding to the basal heatflow at steady state. Generic models not based on any particular known topography quickly stabilise a <span class="hlt">hydrothermal</span> system in the fault slot with a single upflow zone close to the model edge with highest topography. In models with a depth of circulation in the fault slot of about 6 km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS51E..05Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS51E..05Z"><span id="translatedtitle">Characteristics of <span class="hlt">Hydrothermal</span> Mineralization in Ultraslow Spreading Ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.</p> <p>2014-12-01</p> <p><span class="hlt">Hydrothermal</span> activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of <span class="hlt">hydrothermal</span> systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining <span class="hlt">hydrothermal</span> activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of <span class="hlt">hydrothermal</span> mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag <span class="hlt">hydrothermal</span> field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in <span class="hlt">hydrothermal</span> fields. Structures formed by lower temperature activities in active and dead <span class="hlt">hydrothermal</span> fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in <span class="hlt">hydrothermal</span> chimneys. Distribution of diverse low temperature <span class="hlt">hydrothermal</span> activities is consistence with the deep heating mechanisms and <span class="hlt">hydrothermal</span> circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4613831','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4613831"><span id="translatedtitle">Zonation of Microbial Communities by a <span class="hlt">Hydrothermal</span> Mound in the Atlantis II Deep (the Red Sea)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Yong; Li, Jiang Tao; He, Li Sheng; Yang, Bo; Gao, Zhao Ming; Cao, Hui Luo; Batang, Zenon; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan</p> <p>2015-01-01</p> <p>In deep-sea geothermal rift zones, the dispersal of <span class="hlt">hydrothermal</span> fluids of moderately-high temperatures typically forms subseafloor mounds. Major mineral components of the crust covering the mound are barite and metal sulfides. As a result of the continental rifting along the Red Sea, metalliferous sediments accumulate on the seafloor of the Atlantis II Deep. In the present study, a barite crust was identified in a sediment core from the Atlantis II Deep, indicating the formation of a <span class="hlt">hydrothermal</span> mound at the sampling <span class="hlt">site</span>. Here, we examined how such a dense barite crust could affect the local environment and the distribution of microbial inhabitants. Our results demonstrate distinctive features of mineral components and microbial communities in the sediment layers separated by the barite crust. Within the mound, archaea accounted for 65% of the community. In contrast, the sediments above the barite boundary were overwhelmed by bacteria. The composition of microbial communities under the mound was similar to that in the sediments of the nearby Discovery Deep and marine cold seeps. This work reveals the zonation of microbial communities after the formation of the <span class="hlt">hydrothermal</span> mound in the subsurface sediments of the rift basin. PMID:26485717</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3274706','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3274706"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> vent fields and chemosynthetic biota on the world's deepest seafloor spreading centre</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Connelly, Douglas P.; Copley, Jonathan T.; Murton, Bramley J.; Stansfield, Kate; Tyler, Paul A.; German, Christopher R.; Van Dover, Cindy L.; Amon, Diva; Furlong, Maaten; Grindlay, Nancy; Hayman, Nicholas; Hühnerbach, Veit; Judge, Maria; Le Bas, Tim; McPhail, Stephen; Meier, Alexandra; Nakamura, Ko-ichi; Nye, Verity; Pebody, Miles; Pedersen, Rolf B.; Plouviez, Sophie; Sands, Carla; Searle, Roger C.; Stevenson, Peter; Taws, Sarah; Wilcox, Sally</p> <p>2012-01-01</p> <p>The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on <span class="hlt">hydrothermal</span> venting, and the biogeography of vent fauna. Here we report the discovery of two <span class="hlt">hydrothermal</span> vent fields on the Mid-Cayman spreading centre. The Von Damm Vent Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature venting in this off-axis setting suggests that the global incidence of vent fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe Vent Field emits copper-enriched fluids and a buoyant plume that rises 1,100 m, consistent with >400 °C venting from the world's deepest known <span class="hlt">hydrothermal</span> system. At both <span class="hlt">sites</span>, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic vents. PMID:22233630</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22233630','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22233630"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> vent fields and chemosynthetic biota on the world's deepest seafloor spreading centre.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Connelly, Douglas P; Copley, Jonathan T; Murton, Bramley J; Stansfield, Kate; Tyler, Paul A; German, Christopher R; Van Dover, Cindy L; Amon, Diva; Furlong, Maaten; Grindlay, Nancy; Hayman, Nicholas; Hühnerbach, Veit; Judge, Maria; Le Bas, Tim; McPhail, Stephen; Meier, Alexandra; Nakamura, Ko-Ichi; Nye, Verity; Pebody, Miles; Pedersen, Rolf B; Plouviez, Sophie; Sands, Carla; Searle, Roger C; Stevenson, Peter; Taws, Sarah; Wilcox, Sally</p> <p>2012-01-01</p> <p>The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on <span class="hlt">hydrothermal</span> venting, and the biogeography of vent fauna. Here we report the discovery of two <span class="hlt">hydrothermal</span> vent fields on the Mid-Cayman spreading centre. The Von Damm Vent Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature venting in this off-axis setting suggests that the global incidence of vent fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe Vent Field emits copper-enriched fluids and a buoyant plume that rises 1,100 m, consistent with >400 °C venting from the world's deepest known <span class="hlt">hydrothermal</span> system. At both <span class="hlt">sites</span>, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic vents. PMID:22233630</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27147438','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27147438"><span id="translatedtitle">Antimicrobial Activity of Marine Bacterial Symbionts Retrieved from Shallow Water <span class="hlt">Hydrothermal</span> Vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eythorsdottir, Arnheidur; Omarsdottir, Sesselja; Einarsson, Hjorleifur</p> <p>2016-06-01</p> <p>Marine sponges and other sessile macro-organisms were collected at a shallow water <span class="hlt">hydrothermal</span> <span class="hlt">site</span> in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the <span class="hlt">hydrothermal</span> vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður <span class="hlt">hydrothermal</span> vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research. PMID:27147438</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SciDr..20...51J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SciDr..20...51J"><span id="translatedtitle">Time-lapse characterization of <span class="hlt">hydrothermal</span> seawater and microbial interactions with basaltic tephra at Surtsey Volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jackson, M. D.; Gudmundsson, M. T.; Bach, W.; Cappelletti, P.; Coleman, N. J.; Ivarsson, M.; Jónasson, K.; Jørgensen, S. L.; Marteinsson, V.; McPhie, J.; Moore, J. G.; Nielson, D.; Rhodes, J. M.; Rispoli, C.; Schiffman, P.; Stefánsson, A.; Türke, A.; Vanorio, T.; Weisenberger, T. B.; White, J. D. L.; Zierenberg, R.; Zimanowski, B.</p> <p>2015-12-01</p> <p>A new International Continental Drilling Program (ICDP) project will drill through the 50-year-old edifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of <span class="hlt">hydrothermal</span> and microbial interactions with basaltic tephra. The volcano, created in 1963-1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, <span class="hlt">site</span> the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of <span class="hlt">hydrothermal</span> and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse <span class="hlt">hydrothermal</span> conditions. Abstracts of research projects are posted at <a href=" http://surtsey.icdp-online.org"target="_blank"> http://surtsey.icdp-online.org</a>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011Litho.124..185H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011Litho.124..185H"><span id="translatedtitle">Deformation and <span class="hlt">hydrothermal</span> metamorphism of gabbroic rocks within the Godzilla Megamullion, Parece Vela Basin, Philippine Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harigane, Yumiko; Michibayashi, Katsuyoshi; Ohara, Yasuhiko</p> <p>2011-06-01</p> <p>Microstructural and petrologic analyses of 7 gabbroic rocks sampled from the medial area of the Godzilla Megamullion (<span class="hlt">site</span> KH07-02-D18), located along the Parece Vela Basin spreading ridge (Parece Vela Rift), Philippine Sea, reveal the development of a high-temperature ductile shear zone associated with <span class="hlt">hydrothermal</span> metamorphism in the lower crust. The deformed gabbroic rocks are petrographically classified into mylonites and an ultramylonite, and are characterized by porphyroclastic textures consisting mainly of coarse plagioclase and clinopyroxene/amphibole porphyroclasts in a fine-grained matrix. Plagioclase crystallographic-preferred orientations vary from (010)[100] and (001)[100] patterns in the mylonites to a weak (001)[100] pattern in the some mylonites and ultramylonite, suggesting a change in the deformation mechanism from dislocation creep to grain-size-sensitive creep with increasing intensity of deformation. The chemical composition of matrix plagioclase is generally more sodic than that of porphyroclasts. Secondary amphibole is ubiquitous, consisting mainly of pargasite and magnesiohornblende (brown hornblende) and actinolite (green hornblende). The mineral assemblage is consistent with the <span class="hlt">hydrothermal</span> metamorphic reaction: clinopyroxene + calcic plagioclase + fluid → amphibole + sodic plagioclase. Compared with deformed gabbroic rocks from the breakaway and termination areas of the Godzilla Megamullion, the samples record ductile shearing under high temperature conditions, possibly related to the development of the Godzilla Megamullion, although <span class="hlt">hydrothermal</span> activity in the medial area appears to have been less intense than in both the breakaway and termination areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008GMS...178..259S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008GMS...178..259S&link_type=ABSTRACT"><span id="translatedtitle">Processes and interactions in macrofaunal assemblages at <span class="hlt">hydrothermal</span> vents: A modeling perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shea, Katriona; Metaxas, Anna; Young, Curtis R.; Fisher, Charles R.</p> <p></p> <p>Our understanding of the biological assemblages at <span class="hlt">hydrothermal</span> vents is growing rapidly, in part facilitated by the coupling of experimental and observational methods with theoretical modeling efforts. We review theoretical approaches in four main areas and link them to empirical studies of the biology of <span class="hlt">hydrothermal</span> vent systems. First, we describe models of dispersal of vent organisms within and among vent <span class="hlt">sites</span>. These models fall broadly into two categories: those based on larval biology and currents that predict dispersal capabilities from a source, and those using genetic data to address historical genetic links between populations. Then we discuss models for individual and population growth at a location and give examples from work in a biologically similar deep-sea environment: cold seeps. Third, we address how these two aspects can be integrated using models that couple dispersal and demography. Last, we summarize existing modeling approaches for community succession in other types of habitats, and outline the conceptual models and the sorts of data that currently exist for <span class="hlt">hydrothermal</span> vent communities. Throughout, we also examine the use of models in improving experimental design.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17148377','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17148377"><span id="translatedtitle">Occurrence and recent long-distance dispersal of deep-sea <span class="hlt">hydrothermal</span> vent shrimps.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tokuda, Gaku; Yamada, Akinori; Nakano, Kazuma; Arita, Nao; Yamasaki, Hideo</p> <p>2006-06-22</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents and methane seeps are extreme environments that have a high concentration of hydrogen sulphide. However, abundant unique invertebrates including shrimps of the family Bresiliidae have been found in such environments. The bresiliid shrimps are believed to have radiated in the Miocene (less than 20 Myr); however, the period when and the mechanisms by which they dispersed across the <span class="hlt">hydrothermal</span> vents and cold seeps in oceans worldwide have not been clarified. In the present study, we collected the deep-sea blind shrimp Alvinocaris longirostris from the <span class="hlt">hydrothermal</span> vent <span class="hlt">site</span> in the Okinawa Trough and carried out the first investigation of the 18S rRNA gene of a bresiliid shrimp. The phylogenetic analysis revealed that the bresiliid shrimp is situated at an intermediate lineage within the infraorder Caridea and shows monophyly with palaemonid shrimps, which live in shallow sea and freshwater. Furthermore, the mitochondrial cytochrome oxidase I (COI) gene sequences were analysed to determine the phylogenetic relationship with known bresiliid shrimps. A. longirostris of the Okinawa Trough had two haplotypes of the COI gene, one of which was identical to the Alvinocaris sp. of the cold seeps in Sagami Bay. These results indicate that a long-distance dispersal of A. longirostris occurred possibly within the last 100,000 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12571592','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12571592"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> recharge and discharge across 50 km guided by seamounts on a young ridge flank.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fisher, A T; Davis, E E; Hutnak, M; Spiess, V; Zühlsdorff, L; Cherkaoui, A; Christiansen, L; Edwards, K; Macdonald, R; Villinger, H; Mottl, M J; Wheat, C G; Becker, K</p> <p>2003-02-01</p> <p><span class="hlt">Hydrothermal</span> circulation within the sea floor, through lithosphere older than one million years (Myr), is responsible for 30% of the energy released from plate cooling, and for 70% of the global heat flow anomaly (the difference between observed thermal output and that predicted by conductive cooling models). <span class="hlt">Hydrothermal</span> fluids remove significant amounts of heat from the oceanic lithosphere for plates typically up to about 65 Myr old. But in view of the relatively impermeable sediments that cover most ridge flanks, it has been difficult to explain how these fluids transport heat from the crust to the ocean. Here we present results of swath mapping, heat flow, geochemistry and seismic surveys from the young eastern flank of the Juan de Fuca ridge, which show that isolated basement outcrops penetrating through thick sediments guide <span class="hlt">hydrothermal</span> discharge and recharge between <span class="hlt">sites</span> separated by more than 50 km. Our analyses reveal distinct thermal patterns at the sea floor adjacent to recharging and discharging outcrops. We find that such a circulation through basement outcrops can be sustained in a setting of pressure differences and crustal properties as reported in independent observations and modelling studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27147438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27147438"><span id="translatedtitle">Antimicrobial Activity of Marine Bacterial Symbionts Retrieved from Shallow Water <span class="hlt">Hydrothermal</span> Vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eythorsdottir, Arnheidur; Omarsdottir, Sesselja; Einarsson, Hjorleifur</p> <p>2016-06-01</p> <p>Marine sponges and other sessile macro-organisms were collected at a shallow water <span class="hlt">hydrothermal</span> <span class="hlt">site</span> in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the <span class="hlt">hydrothermal</span> vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður <span class="hlt">hydrothermal</span> vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6668952','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6668952"><span id="translatedtitle">Significant role of climatic trends on <span class="hlt">hydrothermal</span> activity Coso Hot Springs, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lofgren, B.E. )</p> <p>1990-05-01</p> <p>The <span class="hlt">hydrothermal</span> features of Coso Hot Springs have attracted visitors for 130 yr and scientific investigators for two decades. In 1978, anticipating effects of major geothermal developments nearby, the Naval Weapons Center (NWC) initiated a comprehensive monitoring program at a dozen <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in the Coso Hot Springs area. Nine years of monitoring preceded power production in the nearby Coso geothermal field in July 1987. During this period, steam was rising from numerous vents and gently boiling mud pots. Local rainfall caused increased boiling activity in several mud pots, with some overflowing during wet periods. Then in August 1988, a year after geothermal power production began major changes in hot spring activity commenced. Small mud pots and steamers started to grow and coalesce. In March 1989, mud-pot activity became more violent. Many buried wells failed causing surface activity in other areas to diminish. During ensuing months, large mud cones developed and much of the steam and boiling water occurred in a few major pots. Because the abrupt changes in <span class="hlt">hydrothermal</span> activity followed so closely after nearby geothermal production began, the obvious cause has been attributed to geothermal developments. Studies of NWC baseline monitoring data indicate, however, that no effects of geothermal developments have been felt in the hot springs area. Rainfall and barometric effects account for most of the fluctuations in records of the past decade. Early accounts and field evidence suggest similar changes have occurred in the past.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMOS42A..04W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMOS42A..04W"><span id="translatedtitle">Physical properties and constraints of <span class="hlt">hydrothermal</span> plumes on the Gakkel Ridge during AGAVE 2007</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winsor, P.; Liljebladh, B.; Edmonds, H. N.; Stranne, C.; Nakamura, K.; Reves-Sohn, R. A.; Tupper, G.; Upchurch, L.</p> <p>2007-12-01</p> <p>The unique hydrographic characteristics of the Arctic Ocean have important implications for the dynamical behavior of <span class="hlt">hydrothermal</span> plumes. Some of the main issues include the weak density stratification of the deep bottom layer, topographical effects from a deep axial valley, and high-latitude tides. We address these issues using analytical and numerical models, and comparing the results to hydrographic water column plume data acquired during the Arctic Gakkel Vents Expedition (AGAVE) from July 1 to August 10, 2007. A total of 36 CTD casts were conducted from the icebreaker Oden at two main <span class="hlt">sites</span> (85N 7E and 85N 85E), where different modes of <span class="hlt">hydrothermal</span> circulation appear to generate different kinds of water column plumes. Several plume signals of varying thickness and rise height above the bottom were observed, which implies that several seafloor sources with distinct discharge characteristics were active during the surveys. We use our models to constrain the character of the seafloor sources, and discuss observational strategies for future field work aimed at locating and mapping <span class="hlt">hydrothermal</span> sources in the deep Arctic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22233630','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22233630"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> vent fields and chemosynthetic biota on the world's deepest seafloor spreading centre.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Connelly, Douglas P; Copley, Jonathan T; Murton, Bramley J; Stansfield, Kate; Tyler, Paul A; German, Christopher R; Van Dover, Cindy L; Amon, Diva; Furlong, Maaten; Grindlay, Nancy; Hayman, Nicholas; Hühnerbach, Veit; Judge, Maria; Le Bas, Tim; McPhail, Stephen; Meier, Alexandra; Nakamura, Ko-Ichi; Nye, Verity; Pebody, Miles; Pedersen, Rolf B; Plouviez, Sophie; Sands, Carla; Searle, Roger C; Stevenson, Peter; Taws, Sarah; Wilcox, Sally</p> <p>2012-01-10</p> <p>The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on <span class="hlt">hydrothermal</span> venting, and the biogeography of vent fauna. Here we report the discovery of two <span class="hlt">hydrothermal</span> vent fields on the Mid-Cayman spreading centre. The Von Damm Vent Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature venting in this off-axis setting suggests that the global incidence of vent fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe Vent Field emits copper-enriched fluids and a buoyant plume that rises 1,100 m, consistent with >400 °C venting from the world's deepest known <span class="hlt">hydrothermal</span> system. At both <span class="hlt">sites</span>, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26485717','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26485717"><span id="translatedtitle">Zonation of Microbial Communities by a <span class="hlt">Hydrothermal</span> Mound in the Atlantis II Deep (the Red Sea).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yong; Li, Jiang Tao; He, Li Sheng; Yang, Bo; Gao, Zhao Ming; Cao, Hui Luo; Batang, Zenon; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan</p> <p>2015-01-01</p> <p>In deep-sea geothermal rift zones, the dispersal of <span class="hlt">hydrothermal</span> fluids of moderately-high temperatures typically forms subseafloor mounds. Major mineral components of the crust covering the mound are barite and metal sulfides. As a result of the continental rifting along the Red Sea, metalliferous sediments accumulate on the seafloor of the Atlantis II Deep. In the present study, a barite crust was identified in a sediment core from the Atlantis II Deep, indicating the formation of a <span class="hlt">hydrothermal</span> mound at the sampling <span class="hlt">site</span>. Here, we examined how such a dense barite crust could affect the local environment and the distribution of microbial inhabitants. Our results demonstrate distinctive features of mineral components and microbial communities in the sediment layers separated by the barite crust. Within the mound, archaea accounted for 65% of the community. In contrast, the sediments above the barite boundary were overwhelmed by bacteria. The composition of microbial communities under the mound was similar to that in the sediments of the nearby Discovery Deep and marine cold seeps. This work reveals the zonation of microbial communities after the formation of the <span class="hlt">hydrothermal</span> mound in the subsurface sediments of the rift basin. PMID:26485717</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21835277','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21835277"><span id="translatedtitle">2-D difference gel electrophoresis approach to assess protein expression profiles in Bathymodiolus azoricus from Mid-Atlantic Ridge <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Company, Rui; Antúnez, Oreto; Bebianno, Maria João; Cajaraville, Miren P; Torreblanca, Amparo</p> <p>2011-11-18</p> <p><span class="hlt">Hydrothermal</span> vent mussels Bathymodiolus azoricus are naturally exposed to toxic chemical species originated directly from vent chimneys. The amount of toxic elements varies significantly among vent <span class="hlt">sites</span> along the Mid-Atlantic Ridge and B. azoricus must be able to adapt to changes in <span class="hlt">hydrothermal</span> fluid composition, temperature and pressure. The aim of this work was to study changes in the proteome in the "gill-bacteria complex" of mussels B. azoricus from three <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> with distinct environmental characteristics using 2-D Fluorescence Difference Gel Electrophoresis (2-D DIGE). Results showed that 31 proteins had different expression profiles among vent <span class="hlt">sites</span> and both cluster and principal component analysis confirm a clear separation of mussels between <span class="hlt">sites</span>. This suggests the existence of specific parameters grouping individuals from the same <span class="hlt">hydrothermal</span> <span class="hlt">site</span>. Protein spots of the more abundant differentially expressed proteins were excised, digested with trypsin and identified by mass spectrometry. All identified proteins (actin, ubiquinone, S-adenosylhomocysteine hydrolase, cysteine peptidases, chaperonin and catalase) have been related previously with oxidative stress conditions and are known to be affected by ROS inducing stressors, including metals. Results point out to specific adaptations at the proteome level of B. azoricus depending on the level of toxicants present in their environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.H13C0991Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.H13C0991Y"><span id="translatedtitle">Reactive transport modeling of <span class="hlt">hydrothermal</span> circulation in oceanic crust: effect of anhydrite precipitation on the dynamics of submarine <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, J.</p> <p>2009-12-01</p> <p><span class="hlt">Hydrothermal</span> fluid circulation represents an extremely efficient mechanism for the exchange of heat and matter between seawater and oceanic crust. Precipitation and dissolution of minerals associated with <span class="hlt">hydrothermal</span> flow at ridge axes can alter the crustal porosity and permeability and hence influence the dynamics of <span class="hlt">hydrothermal</span> systems. In this study, a fully coupled fluid flow, heat transfer and reactive mass transport model was developed using TOUGHREACT to evaluate the role of mineral precipitation and dissolution on the evolution of <span class="hlt">hydrothermal</span> flow systems, with a particular attention focused on anhydrite precipitation upon heating of seawater in recharge zones and the resultant change in the crustal porosity and permeability. A series of numerical case studies were carried out to assess the effect of temperature and aqueous phase inflow concentrations on the reactive geochemical system. The impact of chemically induced porosity and permeability changes on the dynamics of <span class="hlt">hydrothermal</span> systems was also addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26925032','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26925032"><span id="translatedtitle">The Guaymas Basin Hiking Guide to <span class="hlt">Hydrothermal</span> Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface <span class="hlt">Hydrothermal</span> Circulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teske, Andreas; de Beer, Dirk; McKay, Luke J; Tivey, Margaret K; Biddle, Jennifer F; Hoer, Daniel; Lloyd, Karen G; Lever, Mark A; Røy, Hans; Albert, Daniel B; Mendlovitz, Howard P; MacGregor, Barbara J</p> <p>2016-01-01</p> <p>The <span class="hlt">hydrothermal</span> mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface <span class="hlt">hydrothermal</span> circulation patterns. In this overview, we document the most frequently visited features of this <span class="hlt">hydrothermal</span> area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and <span class="hlt">hydrothermal</span> sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these <span class="hlt">hydrothermal</span> features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4757712','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4757712"><span id="translatedtitle">The Guaymas Basin Hiking Guide to <span class="hlt">Hydrothermal</span> Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface <span class="hlt">Hydrothermal</span> Circulation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Teske, Andreas; de Beer, Dirk; McKay, Luke J.; Tivey, Margaret K.; Biddle, Jennifer F.; Hoer, Daniel; Lloyd, Karen G.; Lever, Mark A.; Røy, Hans; Albert, Daniel B.; Mendlovitz, Howard P.; MacGregor, Barbara J.</p> <p>2016-01-01</p> <p>The <span class="hlt">hydrothermal</span> mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface <span class="hlt">hydrothermal</span> circulation patterns. In this overview, we document the most frequently visited features of this <span class="hlt">hydrothermal</span> area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and <span class="hlt">hydrothermal</span> sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these <span class="hlt">hydrothermal</span> features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region. PMID:26925032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26925032','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26925032"><span id="translatedtitle">The Guaymas Basin Hiking Guide to <span class="hlt">Hydrothermal</span> Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface <span class="hlt">Hydrothermal</span> Circulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teske, Andreas; de Beer, Dirk; McKay, Luke J; Tivey, Margaret K; Biddle, Jennifer F; Hoer, Daniel; Lloyd, Karen G; Lever, Mark A; Røy, Hans; Albert, Daniel B; Mendlovitz, Howard P; MacGregor, Barbara J</p> <p>2016-01-01</p> <p>The <span class="hlt">hydrothermal</span> mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface <span class="hlt">hydrothermal</span> circulation patterns. In this overview, we document the most frequently visited features of this <span class="hlt">hydrothermal</span> area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and <span class="hlt">hydrothermal</span> sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these <span class="hlt">hydrothermal</span> features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region. PMID:26925032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003JGRB..108.2377H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003JGRB..108.2377H&link_type=ABSTRACT"><span id="translatedtitle">A fluorescein tracer release experiment in the <span class="hlt">hydrothermally</span> active crater of Vailulu'u volcano, Samoa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hart, S. R.; Staudigel, H.; Workman, R.; Koppers, A. A. P.; Girard, A. P.</p> <p>2003-08-01</p> <p>On 3 April 2001, a 20 kg point source of fluorescein dye was released 30 m above the bottom of the active summit caldera of Vailulu'u submarine volcano, Samoa. Vailulu'u crater is 2000 m wide and at water depths of 600-1000 m, with the bottom 200 m completely enclosed; it thus provides an ideal <span class="hlt">site</span> to study the hydrodynamics of an active <span class="hlt">hydrothermal</span> system. The magmatically driven <span class="hlt">hydrothermal</span> system in the crater is currently exporting massive amounts of particulates, manganese, and helium. The dispersal of the dye was tracked for 4 days with a fluorimeter in tow-yo mode from the U.S. Coast Guard icebreaker Polar Sea. Lateral dispersion of the dye ranged from 80 to 500 m d-1; vertical dispersion had two components: a diapycnal diffusivity component averaging 21 cm2 s-1, and an advective component averaging 0.025 cm s-1. These measurements constrain the mass export of water from the crater during this period to be 8-1.3+4.6 × 107 m3 d-1, which leads to a "turnover" time for water in the crater of ˜3.2 days. Coupled with temperature data from CTD profiles and Mn analyses of water samples, the power output from the crater is 610-100+350 MW, and the manganese export flux is ˜240 kg d-1. The Mn/Heat ratio of 4.7 ng J-1 is significantly lower than ratios characteristic of hot smokers and diffuse <span class="hlt">hydrothermal</span> flows on mid-ocean ridges and points to phase separation processes in this relatively shallow <span class="hlt">hydrothermal</span> system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1058H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1058H"><span id="translatedtitle">Chemistry of <span class="hlt">Hydrothermal</span> Plumes at 159°E on the Australian-Antarctic Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hahm, D.; Baker, E. T.; Rhee, T. S.; Lupton, J. E.; Resing, J. A.; Park, S. H.</p> <p>2014-12-01</p> <p>The Australian-Antarctic Ridge (AAR) is one of the largest unexplored regions of the global mid-ocean ridge system. In the present contribution, we present the geochemistry of the <span class="hlt">hydrothermal</span> plumes over the KR1, an AAR segment at 159ºE and 62ºS. In 2011, we collected 48 Miniature Autonomous Plume Recorder profiles, measuring optical back scatter and oxidation-reduction potential, and identified the area between 158.5 and 159ºE as the densest concentration of active <span class="hlt">hydrothermal</span> <span class="hlt">sites</span>. In order to further characterize the chemistry of the <span class="hlt">hydrothermal</span> plumes over the area, named 'Mujin', we conducted intensive vertical and tow-yo CTD casts in 2013. The maximum concentrations of the chemical tracers 3He, CH4, H2, and dissolved Mn, were 7.47 fmol/kg, 19.6 nmol/kg, 8.8 nmol/kg, 94.3 nmol/L, respectively. The CH4/3He (1 -10) and CH4/Mn (0.01 - 0.2) ratios were significantly lower than many ultra-mafic hosted systems, which are often found in slow spreading ridges. The lower ratios are consistent with a basaltic-hosted system, typical of the intermediate spreading rate of 6.8 cm/yr of KR1. Additionally, some of the plume samples collected around 158.6 and 158.8ºE exhibited slightly higher ratios of H2/3He than the others. Assuming that H2 is produced from the reduction of water by reduced iron compounds in the rock, the higher ratios suggest that those plumes are supported by a younger <span class="hlt">hydrothermal</span> system, which may have experienced a recent eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=201505','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=201505"><span id="translatedtitle">Thermophilic Sulfate Reduction in <span class="hlt">Hydrothermal</span> Sediment of Lake Tanganyika, East Africa</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Elsgaard, Lars; Prieur, Daniel; Mukwaya, Gashagaza M.; Jørgensen, Bo B.</p> <p>1994-01-01</p> <p>In environments with temperatures above 60°C, thermophilic prokaryotes are the only metabolically active life-forms. By using the 35SO42- tracer technique, we studied the activity of sulfate-reducing microorganisms (SRM) in hot sediment from a <span class="hlt">hydrothermal</span> vent <span class="hlt">site</span> in the northern part of freshwater Lake Tanganyika (East Africa). Incubation of slurry samples at 8 to 90°C demonstrated meso- and thermophilic sulfate reduction with optimum temperatures of 34 to 45°C and 56 to 65°C, respectively, and with an upper temperature limit of 80°C. Sulfate reduction was stimulated at all temperatures by the addition of short-chain fatty acids and benzoate or complex substrates (yeast extract and peptone). A time course experiment showed that linear thermophilic sulfate consumption occurred after a lag phase (12 h) and indicated the presence of a large population of SRM in the <span class="hlt">hydrothermal</span> sediment. Thermophilic sulfate reduction had a pH optimum of about 7 and was completely inhibited at pH 8.8 to 9.2. SRM could be enriched from <span class="hlt">hydrothermal</span> chimney and sediment samples at 60 and 75°C. In lactate-grown enrichments, sulfide production occurred at up to 70 and 75°C, with optima at 63 and 71°C, respectively. Several sporulating thermophilic enrichments were morphologically similar to Desulfotomaculum spp. Dissimilatory sulfate reduction in the studied <span class="hlt">hydrothermal</span> area of Lake Tanganyika apparently has an upper temperature limit of 80°C. PMID:16349249</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/890518','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/890518"><span id="translatedtitle">Deep Borehole Measurements for Characterizing the Magma/<span class="hlt">Hydrothermal</span> System at Long Valley Caldera, CA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carrrigan, Charles R.</p> <p>1989-03-21</p> <p>The Magma Energy Program of the Geothermal Technology Division is scheduled to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California in 1989. The drilling <span class="hlt">site</span> is near the center of the caldera which is associated with numerous shallow (5-7 km) geophysical anomalies. This deep well will present an unparalleled opportunity to test and validate geophysical techniques for locating magma as well as a test of the theory that magma is still present at drillable depths within the central portion of the caldera. If, indeed, drilling indicates magma, the geothermal community will then be afforded the unique possibility of examining the coupling between magmatic and <span class="hlt">hydrothermal</span> regimes in a major volcanic system. Goals of planned seismic experiments that involve the well include the investigation of local crustal structure down to depths of 10 km as well as the determination of mechanisms for local seismicity and deformation. Borehole electrical and electromagnetic surveys will increase the volume and depth of rock investigated by the well through consideration of the conductive structure of the <span class="hlt">hydrothermal</span> and underlying regimes. Currently active processes involving magma injection will be studied through observation of changes in pore pressure and strain. Measurements of in situ stress from recovered cores and hydraulic fracture tests will be used in conjunction with uplift data to determine those models for magmatic injection and inflation that are most applicable. Finally, studies of the thermal regime will be directed toward elucidating the coupling between the magmatic source region and the more shallow <span class="hlt">hydrothermal</span> system in the caldera fill. To achieve this will require careful logging of borehole fluid temperature and chemistry. In addition, studies of rock/fluid interactions through core and fluid samples will allow physical characterization of the transition zone between <span class="hlt">hydrothermal</span> and magmatic regimes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V32A0959O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V32A0959O"><span id="translatedtitle">Study of <span class="hlt">Hydrothermal</span> Particulate Matter from a Shallow Venting System, offshore Nayarit, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortega-Osorio, A.; Prol-Ledesma, R. M.; Reyes, A. G.; Rubio-Ramos, M. A.; Torres-Vera, M. A.</p> <p>2001-12-01</p> <p>A shallow (30 ft) <span class="hlt">hydrothermal</span> <span class="hlt">site</span> named ``Cora'' (after the indigenous people thereby) was surveyed and sampled throughout direct observation with SCUBA diving during November 25 to December 4, 2000. A total of 10 dives were conducted in order to obtain representative samples from an 85oC fluid source of approximately 10 cm in diameter. Inherent difficulties to the sampling, such as poor visibility and strong bottom currents were overcome and samples of <span class="hlt">hydrothermal</span> fluid, gas, rocks, and particulate matter were collected directly from the vent. Water samples and <span class="hlt">hydrothermal</span> fluid were taken with a homemade 1 l cylindrical bottles of two lines by flushing in from the bottom for about ten minutes until total displacement of the seawater; similar procedure was carried out for gas samples. Particulate matter was collected with 0.4mm polycarbonate membrane filters and preserved in a desiccators at a fridge temperature until analysis onshore. Preliminary description of the rock samples suggest that pyritization is the main mineralisation process. Filters containing <span class="hlt">hydrothermal</span> particulate matter were surveyed under the scanning electron microscope in order to identify the nature (inorganic and organic), as well as the chemistry of the particles. SEM examination revealed the presence of particles of different kind that suggests high degree of mixing and re-suspension: Planctonic organisms and organic matter appeared to be abundant; 25 micron particles of different carbonate faces and inorganic particles of silicates were also recognized. Distinctive euhedral colloidal grains were identified as the resulting process of precipitation from the solution. Microanalysis of iron and sulfur content of 10 micron particles indicate a very likely sulphide mineral face (greigite); 8 micron cinnabar particles are consistent with the mineralization conditions, observed as well in the inner walls of the vent. Analyses of dissolved and particulate trace metals are still ongoing at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1050D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1050D"><span id="translatedtitle">Application of AUVs in the Exploration for and Characterization of Arc Volcano Seafloor <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Ronde, C. E. J.; Walker, S. L.; Caratori Tontini, F.; Baker, E. T.; Embley, R. W.; Yoerger, D.</p> <p>2014-12-01</p> <p>The application of Autonomous Underwater Vehicles (AUVs) in the search for, and characterization of, seafloor <span class="hlt">hydrothermal</span> systems associated with arc volcanoes has provided important information at a scale relevant to the study of these systems. That is, 1-2 m resolution bathymetric mapping of the seafloor, when combined with high-resolution magnetic and water column measurements, enables the discharge of <span class="hlt">hydrothermal</span> vent fluids to be coupled with geological and structural features, and inferred upflow zones. Optimum altitude for the AUVs is ~70 m ensuring high resolution coverage of the area, maximum exposure to <span class="hlt">hydrothermal</span> venting, and efficency of survey. The Brothers caldera and Clark cone volcanoes of the Kermadec arc have been surveyed by ABE and Sentry. At Brothers, bathymetric mapping shows complex features on the caldera walls including embayment's, ridges extending orthogonal to the walls and the location of a dominant ring fault. Water column measurements made by light scattering, temperature, ORP and pH sensors confirmed the location of the known vent fields on the NW caldera wall and atop the two cones, and discovered a new field on the West caldera wall. Evidence for diffuse discharge was also seen on the rim of the NW caldera wall; conversely, there was little evidence for discharge over an inferred ancient vent <span class="hlt">site</span> on the SE caldera wall. Magnetic measurements show a strong correlation between the boundaries of vent fields determined by water column measurements and observed from manned submersible and towed camera surveys, and donut-shaped zones of magnetic 'lows' that are focused along ring faults. A magnetic low was also observed to cover the SE caldera <span class="hlt">site</span>. Similar surveys over the NW edifice of Clark volcano also show a strong correlation between active <span class="hlt">hydrothermal</span> venting and magnetic lows. Here, the survey revealed a pattern resembling Swiss cheese of magnetic lows, indicating more widespread permeability. Moreover, the magnetic survey</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B13C0509B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B13C0509B"><span id="translatedtitle">Investigating the effect of <span class="hlt">hydrothermal</span> conditions on the subvent biosphere of the Okinawa backarc basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandt, L. D.; House, C. H.; Nunoura, T.; Yanagawa, K.</p> <p>2013-12-01</p> <p>IODP Expedition 331 to the Okinawa backarc basin provided an opportunity to study an interesting subset of the ocean floor -- the subsurface environment surrounding an active <span class="hlt">hydrothermal</span> vent. The subsurface sediments of the Iheya North Field within the mid-Okinawa trough are affected by high temperature fluids. In addition, the Okinawa backarc basin is situated on a continental margin. This particular environment has a unique set of conditions for investigating the vertical variability in microbial communities with depth as conditions become increasingly restrictive. IODP Expedition 331 <span class="hlt">Site</span> C0014, located 450 m east of the active vent, has a surface temperature of 5°C and has no evidence of <span class="hlt">hydrothermal</span> alteration. Temperature increases with depth at an estimated rate of 3°C/m. Below a depth of ~10 mbsf, the sedimentary sequence is <span class="hlt">hydrothermally</span> altered to a pale, gray clay with alteration products illite and montmorillonite. Thus, <span class="hlt">Site</span> C0014 represents an ideal location to characterize whether 1) the microbial community structure shifts from non-<span class="hlt">hydrothermal</span> margin microorganisms toward a more temperature-adapted group of microorganisms, or 2) repeating clades represented throughout the sediment column are seemingly adapting to the increasingly extreme conditions. DNA from sediments (0-44 mbsf) was extracted using a modified protocol from the MoBio PowerSoil DNA Isolation kit. Primers were designed to amplify the V6-V9 region of the 16S rRNA gene. Select samples were sequenced with the Roche 454 FLX sequencer at The Pennsylvania State University. The amplicon data suggest that the subvent biosphere resides in the top 12-14 meters below seafloor (mbsf). The archaeal sequences abruptly disappear beyond the 14 mbsf horizon. The phylum Euryarchaeota, dominated by Deep Sea <span class="hlt">Hydrothermal</span> Vent Group 6 (DHVEG-6) and ANME-1, are present throughout the top 14 meters. However, there is an increasingly stronger signal of non-Euryarchaeota clades Marine Crenarchaeotic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.B33A1018S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.B33A1018S"><span id="translatedtitle">Fate of liquid CO2 discharged from the <span class="hlt">hydrothermal</span> area in the Okinawa Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shitashima, K.; Maeda, Y.</p> <p>2005-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> systems are suitable for the on-<span class="hlt">site</span> field analysis of a high CO2 environment in the ocean. <span class="hlt">Hydrothermal</span> fluids are highly enriched in CO2 and show lower pH (about pH2-3) relative to seawater. The observation of the <span class="hlt">hydrothermal</span> CO2 would provide the opportunity for understanding the physic-chemical behavior and diffusion process of CO2 in the ocean. Furthermore, the information on the <span class="hlt">hydrothermal</span> ecosystem in the high CO2 environment is important for an environment impact assessment of the CO2 ocean sequestration. The observation of behavior of natural CO2 droplets (8-10?, 0.5ml) was carried out in the deep-sea <span class="hlt">hydrothermal</span> system at the Okinawa Trough. The natural CO2 droplet contains CO2 of 95-98%, H2S of 2-3% and other gas species. The rising CO2 droplets were tracked by an ROV, and depth, temperature, salinity, pH and pCO2 in seawater near the CO2 droplets were measured during their ascent by using CTD and in-situ pH/pCO2 sensor. The behavior of the rising CO2 droplets was observed with an HDTV camera on an ROV. Mapping survey (400m X 400m, 3 layers) of low pH distribution was performed on the natural CO2 venting area by the grid navigation of the ROV that installed a pH/pCO2 sensor. The droplet size and the rise rate of CO2 droplets decreased during their ascent in water column (from 1470m to 900m depth). The CO2 droplets dissolved gradually and became small CO2 clathrate while rising, and the rising clathrate materials were found to disappear at 918m depth (552m above the bottom). Although the pH just above the sea floor CO2 vents showed pH 5, the pH depression in seawater surrounding the rising CO2 droplets was not observed. The results of pH mapping survey showed only localized pH depression at the CO2 venting <span class="hlt">site</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMOS43A0989S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMOS43A0989S"><span id="translatedtitle">Macrofauna of shallow <span class="hlt">hydrothermal</span> vents on the Arctic Mid-Ocean Ridge at 71N</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schander, C.; Rapp, H. T.; Pedersen, R. B.</p> <p>2007-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents are usually associated with a highly specialized fauna and since their discovery in 1977, more than 400 species of animals have been described. Specialized vent fauna includes various animal phyla, but the most conspicuous and well known are annelids, mollusks and crustaceans. We have investigated the fauna collected around newly discovered <span class="hlt">hydrothermal</span> vents on the Mohns Ridge north of Jan Mayen. The venting fields are located at 71°N and the venting takes place within two main areas separated by 5 km. The shallowest vent area is at 500-550 m water depth and is located at the base of a normal fault. This vent field stretches approximately 1 km along the strike of the fault, and it is composed of 10-20 major vent <span class="hlt">sites</span> each with multiple chimney constructions discharging up to 260°C hot fluids. A large area of diffuse, low- temperature venting occurs in the area surrounding the high-temperature field. Here, partly microbial mediated iron-oxide-hydroxide deposits are abundant. The <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> do not show any high abundance of specialized <span class="hlt">hydrothermal</span> vent fauna. Single groups (i.e. Porifera and Mollusca) have a few representatives but groups otherwise common in <span class="hlt">hydrothermal</span> vent areas (e.g. vestimentifera, Alvinellid worms, mussels, clams, galathaeid and brachyuran crabs) are absent. Up until now slightly more than 200 species have been identified from the vent area. The macrofauna found in the vent area is, with few exceptions, an assortment of bathyal species known in the area. One endemic, yet undescribed, species of mollusc has been found so far, an gastropod related to Alvania incognita Warén, 1996 and A. angularis Warén, 1996 (Rissoidae), two species originally described from pieces of sunken wood north and south of Iceland. It is by far the most numerous mollusc species at the vents and was found on smokers, in the bacterial mats, and on the ferric deposits. A single specimen of an undescribed tanaidacean has also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V52A..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V52A..01S"><span id="translatedtitle">Ultramafic-hosted <span class="hlt">Hydrothermal</span> Systems at Mid-Ocean Ridges: Serpentinization, Chloritization and Geochemical Controls on Mass-Transfer Processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seyfried, W. E.; Pester, N. J.; Ding, K.</p> <p>2012-12-01</p> <p>Recent studies of seafloor <span class="hlt">hydrothermal</span> systems associated with the slow spreading Mid-Atlantic Ridge have provided a wealth of information on the complex interplay between tectonic and magmatic processes that ultimately govern the chemical and physical evolution of these systems. The Lost City <span class="hlt">hydrothermal</span> field (LCHF)(30°N) and the Rainbow <span class="hlt">hydrothermal</span> system (36°N), for example, provide contrasting styles of heat and mass transfer that result in very different constraints on the composition of <span class="hlt">hydrothermal</span> fluids. <span class="hlt">Hydrothermal</span> fluids were sampled and analyzed during a series of ROV (Jason II) supported dives in 2008 to these and related vent <span class="hlt">sites</span> along the northern MAR. In addition to deployment of conventional vent fluid sampling devices, in-situ chemical sensor systems were also used to better constrain pH and redox reactions. The general characteristics of the Lost City <span class="hlt">hydrothermal</span> field, which is offset approximately 15km from the MAR owing to tectonic effects imposed by the emplacement of the Atlantis Massif, have been extensively reviewed in recent years. Vent fluids issuing from this peridotite-hosted system reveal temperatures of approximately 90-100°C, high concentrations of dissolved hydrogen and methane, and pH measured (25°C) values that exceed 10. The relatively low vent fluid temperatures notwithstanding, phase equilibria constraints imposed by dissolved Ca and sulfate suggest temperatures of approximately 200°C at depth, below the seafloor. New data for dissolved silica indicate a <span class="hlt">hydrothermal</span> "root zone" lacking brucite, but where fluid chemistry and pH is buffered by serpentine-diopside-fluid equilibria. Consistent with previously published strontium and boron isotope measurements, data reported here for trace alkali elements (Cs, Rb, Li) indicate high fluid/rock mass ratios. Variably low dissolved Fe concentrations are broadly consistent with constraints imposed by magnetite-fluid equilibria at the high measured dissolved H2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1817495B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1817495B&link_type=ABSTRACT"><span id="translatedtitle">Entropy Production in Convective <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boersing, Nele; Wellmann, Florian; Niederau, Jan</p> <p>2016-04-01</p> <p>Exploring <span class="hlt">hydrothermal</span> reservoirs requires reliable estimates of subsurface temperatures to delineate favorable locations of boreholes. It is therefore of fundamental and practical importance to understand the thermodynamic behavior of the system in order to predict its performance with numerical studies. To this end, the thermodynamic measure of entropy production is considered as a useful abstraction tool to characterize the convective state of a system since it accounts for dissipative heat processes and gives insight into the system's average behavior in a statistical sense. Solving the underlying conservation principles of a convective <span class="hlt">hydrothermal</span> system is sensitive to initial conditions and boundary conditions which in turn are prone to uncertain knowledge in subsurface parameters. There exist multiple numerical solutions to the mathematical description of a convective system and the prediction becomes even more challenging as the vigor of convection increases. Thus, the variety of possible modes contained in such highly non-linear problems needs to be quantified. A synthetic study is carried out to simulate fluid flow and heat transfer in a finite porous layer heated from below. Various two-dimensional models are created such that their corresponding Rayleigh numbers lie in a range from the sub-critical linear to the supercritical non-linear regime, that is purely conductive to convection-dominated systems. Entropy production is found to describe the transient evolution of convective processes fairly well and can be used to identify thermodynamic equilibrium. Additionally, varying the aspect ratio for each Rayleigh number shows that the variety of realized convection modes increases with both larger aspect ratio and higher Rayleigh number. This phenomenon is also reflected by an enlarged spread of entropy production for the realized modes. Consequently, the Rayleigh number can be correlated to the magnitude of entropy production. In cases of moderate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V23B0614G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V23B0614G"><span id="translatedtitle">The Sasquatch <span class="hlt">Hydrothermal</span> Field: Linkages Between Seismic Activity, <span class="hlt">Hydrothermal</span> Flow, and Geology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Glickson, D. A.; Kelley, D. S.; Delaney, J. R.</p> <p>2006-12-01</p> <p>The Sasquatch <span class="hlt">Hydrothermal</span> Field is the most northern known vent field along the central Endeavour Segment of the Juan de Fuca Ridge, located 6 km north of the Main Endeavour Field (MEF) near 47° 59.8'N, 129° 4.0'W. It was discovered in 2000, after two large earthquake swarms in June 1999 and January 2000 caused increased venting temperatures in the MEF and significant changes in volatile composition along the entire axis [Johnson et al., 2000; Lilley et al., 2003; Proskurowski et al., 2004]. From 2004-2006, Sasquatch and the surrounding axial valley were comprehensively mapped with SM2000 multibeam sonar system and Imagenex scanning sonar at a resolution of 1-5 m. These data were combined with visual imagery from Alvin and ROV dives to define the eruptive, <span class="hlt">hydrothermal</span>, and tectonic characteristics of the field and distal areas. Based on multibeam sonar results, bathymetric relief of the segment near Sasquatch is subdued. The broad axial valley is split by a central high that rises 30-40 m above the surrounding seafloor. Simple pattern analysis of the valley shows two fundamentally different regions, distinguished by low and high local variance. Areas of low variance correspond to a collapse/drainback landscape characterized by ropy sheet flow, basalt pillars, and bathtub rings capped by intact and drained lobate flows. Areas of high variance generally correspond to three types of ridge structures: 1) faulted basalt ridges composed of truncated pillow basalt, rare massive flows, and widespread pillow talus; 2) constructional basalt ridges composed of intact pillow flow fronts; and 3) extinct sulfide ridges covered by varying amounts of sulfide talus and oxidized <span class="hlt">hydrothermal</span> sediment. Sasquatch is located in a depression among truncated pillow ridges, and is comprised of ~10, 1-6 m high, fragile sulfide chimneys that vent fluids up to 289°C. The active field extends only ~25 x 25 m, although a linear, N-S trending ridge of nearly continuous extinct sulfide</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22325568','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22325568"><span id="translatedtitle">New digestive symbiosis in the <span class="hlt">hydrothermal</span> vent amphipoda Ventiella sulfuris.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Corbari, Laure; Durand, Lucile; Cambon-Bonavita, Marie-Anne; Gaill, Françoise; Compère, Philippe</p> <p>2012-02-01</p> <p>Ventiella sulfuris Barnard and Ingram, 1990 is the most abundant amphipod species inhabiting the Eastern Pacific Rise (EPR 9°N) vent fields. This vent-endemic species is frequently encountered near colonies of Pompeii worms Alvinella pompejana. V. sulfuris specimens were collected during the oceanographic cruise LADDER II at the Bio9 (9°50.3'N, 2508m depth) <span class="hlt">hydrothermal</span> vent <span class="hlt">site</span>. Main objectives were to highlight the occurrence of bacterial symbiosis in V. sulfuris and to hypothesise their implications in nutrition. Observations in light and electron microscopy (SEM, TEM) showed that the outer body surface and appendages are free of microorganisms. In contrast, the digestive system revealed two major microbial communities settled in the midgut and in the hindgut. Gut contents showed bacterial traces together with abundant fragments of Alvinellid cuticle and setae, from A. pompejana, suggesting that V. sulfuris could directly feed on Alvinellids and/or on their bacterial epibionts. Molecular analyses based on the 16S rRNA genes revealed the diversity of bacterial communities in the digestive system, of which, the Epsilonproteobacteria phylum, could be considered as one of the major bacterial group. Hypotheses were proposed on their symbiotic features and their implications in V. sulfuris nutrition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10135851','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10135851"><span id="translatedtitle">Destruction of nitrates, organics, and ferrocyanides by <span class="hlt">hydrothermal</span> processing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robinson, J.M.; Foy, B.R.; Dell`Orco, P.C.; Anderson, G.; Archuleta, F.; Atencio, J.; Breshears, D.; Brewer, R.; Eaton, H.; McFarland, R.; McInroy, R.; Reynolds, T.; Sedillo, M.; Wilmanns, E.; Buelow, S.J.</p> <p>1993-03-01</p> <p>This work targets the remediation of the aqueous mixed wastes stored in the underground tanks at the Department of Energy <span class="hlt">site</span> in Hanford, Washington via <span class="hlt">hydrothermal</span> processing. The feasibility of destroying the nitrate, organic, and ferrocyanide components of the wastes under supercritical and near critical conditions (623 {degree}K to 873{degree}K, 22.1 MPa to 103.4 MPa) is addressed. A novel method was developed for determining the solubility of nitrate salts in supercritical water solutions at pressures ranging from 24.8 MPa to 30.3 MPa (3600 psi to 4400 psi) and temperatures from 723 {degree}K to 798 {degree}K. Sodium nitrate solubilities ranged from 293 mg/kg at 24.8 MPa and 798 {degree}K to 1963 mg/kg at 30.3 MPa and 723{degree}K. Solubility was found to vary directly with pressure, and inversely with temperature. An empirical relationship was developed for the estimation of sodium nitrate solubility at water densities between 0.08 and 0.16 kg/L and temperatures between 723{degree}K and 798{degree}K. A small volume batch reactor equipped with optical diagnostics was used to monitor the phase behavior of a diluted variant of a tank 101-SY simulant. Preliminary results suggest that a single phase is formed at 83 MPa at 773 {degree}K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6546693','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6546693"><span id="translatedtitle">Destruction of nitrates, organics, and ferrocyanides by <span class="hlt">hydrothermal</span> processing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robinson, J.M.; Foy, B.R.; Dell'Orco, P.C.; Anderson, G.; Archuleta, F.; Atencio, J.; Breshears, D.; Brewer, R.; Eaton, H.; McFarland, R.; McInroy, R.; Reynolds, T.; Sedillo, M.; Wilmanns, E.; Buelow, S.J.</p> <p>1993-01-01</p> <p>This work targets the remediation of the aqueous mixed wastes stored in the underground tanks at the Department of Energy <span class="hlt">site</span> in Hanford, Washington via <span class="hlt">hydrothermal</span> processing. The feasibility of destroying the nitrate, organic, and ferrocyanide components of the wastes under supercritical and near critical conditions (623 [degree]K to 873[degree]K, 22.1 MPa to 103.4 MPa) is addressed. A novel method was developed for determining the solubility of nitrate salts in supercritical water solutions at pressures ranging from 24.8 MPa to 30.3 MPa (3600 psi to 4400 psi) and temperatures from 723 [degree]K to 798 [degree]K. Sodium nitrate solubilities ranged from 293 mg/kg at 24.8 MPa and 798 [degree]K to 1963 mg/kg at 30.3 MPa and 723[degree]K. Solubility was found to vary directly with pressure, and inversely with temperature. An empirical relationship was developed for the estimation of sodium nitrate solubility at water densities between 0.08 and 0.16 kg/L and temperatures between 723[degree]K and 798[degree]K. A small volume batch reactor equipped with optical diagnostics was used to monitor the phase behavior of a diluted variant of a tank 101-SY simulant. Preliminary results suggest that a single phase is formed at 83 MPa at 773 [degree]K.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.V72A1299S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V72A1299S"><span id="translatedtitle">Geochemistry of <span class="hlt">hydrothermal</span> plume in the Suiyo Seamount Caldera.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shitashima, K.; Maeda, Y.</p> <p>2002-12-01</p> <p>Chemical compounds of the hot basalt origin are discharged into the deep ocean via <span class="hlt">hydrothermal</span> plume by the deep-sea <span class="hlt">hydrothermal</span> activity. The <span class="hlt">hydrothermal</span> plume is widely diffused to the ocean by mixing with ambient seawater. Chemical reactions and interactions with microorganisms in the diffusion process of the <span class="hlt">hydrothermal</span> plume are important to comprehend the oceanic geochemical cycles. Recently, it has been clarified that the variation of <span class="hlt">hydrothermal</span> activity is greatly controlled in the tidal current. Not only geochemical observation but also physical observation, such as water current measurement, are necessary for the understanding of the deep-sea <span class="hlt">hydrothermal</span> systems including the behavior of <span class="hlt">hydrothermal</span> plume. In order to observe the diffusion process of <span class="hlt">hydrothermal</span> plumes, sampling and chemical mapping of the <span class="hlt">hydrothermal</span> plume and measurement of water current were carried out at the Suiyo Seamount Caldera during research cruises under the ?Archaean Park? project funded by MEXT. The three-dimensional acoustic current meters were moored at the height of 13m and 125m above the bottom in the Suiyo Seamount Caldera. At the 13m height, average water current speed and current direction were 10.46 cm/second and 228.1 degrees, respectively, and maximum water current speed was over 40.46 cm/second. On the other hand, average water current speed and current direction at the 125m height were 3.87 cm/second and 57.8 degrees, respectively. The strong water current of the southwest direction in 24 hours periods existed near bottom of the caldera. In addition, downward current and water temperature depreciation were observed, when there was the strong current in 24 hours periods. These results suggest that the low-temperature ocean water around the Suiyo Seamount flows toward the bottom of caldera periodically. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles and the in-situ pH sensor were installed on the ROV or manned submersible. The <span class="hlt">hydrothermal</span> plume</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010NatGe...3..252T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010NatGe...3..252T"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> contribution to the oceanic dissolved iron inventory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tagliabue, Alessandro; Bopp, Laurent; Dutay, Jean-Claude; Bowie, Andrew R.; Chever, Fanny; Jean-Baptiste, Philippe; Bucciarelli, Eva; Lannuzel, Delphine; Remenyi, Tomas; Sarthou, Géraldine; Aumont, Olivier; Gehlen, Marion; Jeandel, Catherine</p> <p>2010-04-01</p> <p>Iron limits phytoplankton growth and hence the biological carbon pump in the Southern Ocean. Models assessing the impacts of iron on the global carbon cycle generally rely on dust input and sediment resuspension as the predominant sources. Although it was previously thought that most iron from deep-ocean <span class="hlt">hydrothermal</span> activity was inaccessible to phytoplankton because of the formation of particulates, it has been suggested that iron from <span class="hlt">hydrothermal</span> activity may be an important source of oceanic dissolved iron. Here we use a global ocean model to assess the impacts of an annual dissolved iron flux of approximately 9×108mol, as estimated from regional observations of <span class="hlt">hydrothermal</span> activity, on the dissolved iron inventory of the world's oceans. We find the response to the input of <span class="hlt">hydrothermal</span> dissolved iron is greatest in the Southern Hemisphere oceans. In particular, observations of the distribution of dissolved iron in the Southern Ocean (Chever et al., manuscript in preparation; Bowie et al., manuscript in preparation) can be replicated in our simulations only when our estimated iron flux from <span class="hlt">hydrothermal</span> sources is included. As the <span class="hlt">hydrothermal</span> flux of iron is relatively constant over millennial timescales, we propose that <span class="hlt">hydrothermal</span> activity can buffer the oceanic dissolved iron inventory against shorter-term fluctuations in dust deposition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3211500','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3211500"><span id="translatedtitle">Tuning photoluminescence of organic rubrene nanoparticles through a <span class="hlt">hydrothermal</span> process</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2011-01-01</p> <p>Light-emitting 5,6,11,12-tetraphenylnaphthacene (rubrene) nanoparticles (NPs) prepared by a reprecipitation method were treated <span class="hlt">hydrothermally</span>. The diameters of <span class="hlt">hydrothermally</span> treated rubrene NPs were changed from 100 nm to 2 μm, depending on <span class="hlt">hydrothermal</span> temperature. Photoluminescence (PL) characteristics of rubrene NPs varied with <span class="hlt">hydrothermal</span> temperatures. Luminescence of pristine rubrene NPs was yellow-orange, and it changed to blue as the <span class="hlt">hydrothermal</span> temperature increased to 180°C. The light-emitting color distribution of the NPs was confirmed using confocal laser spectrum microscope. As the <span class="hlt">hydrothermal</span> temperature increased from 110°C to 160°C, the blue light emission at 464 to approximately 516 nm from filtered-down NPs was enhanced by H-type aggregation. Filtered-up rubrene NPs treated at 170°C and 180°C exhibited blue luminescence due to the decrease of intermolecular excimer densities with the rapid increase in size. Variations in PL of <span class="hlt">hydrothermally</span> treated rubrene NPs resulted from different size distributions of the NPs. PMID:21711925</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V31B4738I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V31B4738I"><span id="translatedtitle">Refining the Subseafloor Circulation Model of the Middle Valley <span class="hlt">Hydrothermal</span> System Using Fluid Geochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inderbitzen, K. E.; Wheat, C. G.; Baker, P. A.; Fisher, A. T.</p> <p>2014-12-01</p> <p>Currently, fluid circulation patterns and the evolution of rock/fluid compositions as circulation occurs in subseafloor <span class="hlt">hydrothermal</span> systems are poorly constrained. Sedimented spreading centers provide a unique opportunity to study subsurface flow because sediment acts as an insulating blanket that traps heat from the cooling magma body and limits: (a) potential flow paths for seawater to recharge the aquifer in permeable upper basaltic basement and (b) points of altered fluid egress. This also allows for a range of thermal and geochemical gradients to exist near the sediment-water interface. Models of fluid circulation patterns in this type of hydrologic setting have been generated (eg. Stein and Fisher, 2001); however fluid chemistry datasets have not previously been used to test the model's viability. We address this issue by integrating the existing circulation model with fluid compositional data collected from sediment pore waters and high temperature <span class="hlt">hydrothermal</span> vents located in Middle Valley on the Juan de Fuca Ridge. Middle Valley hosts a variety of hydrologic regimes: including areas of fluid recharge (<span class="hlt">Site</span> 855), active venting (<span class="hlt">Site</span> 858/1036; Dead Dog vent field), recent venting (<span class="hlt">Site</span> 856/1035; Bent Hill Massive Sulfide deposit) and a section of heavily sedimented basement located between recharge and discharge <span class="hlt">sites</span> (<span class="hlt">Site</span> 857). We will present new results based on thermal and geochemical data from the area of active venting (<span class="hlt">Sites</span> 858 and 1036), that was collected during Ocean Drilling Program Legs 139 and 169 and a subsequent heat flow/gravity coring effort. These results illuminate fine scale controls on secondary recharge and fluid flow within the sediment section at <span class="hlt">Site</span> 858/1036. The current status of high temperature vents in this area (based on observations made in July, 2014) will also be outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1731e0140K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1731e0140K"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of vanadium pentoxide nanowires</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, J. Santhosh; Thangadurai, P.</p> <p>2016-05-01</p> <p>Nanowires of V2O5 were prepared via <span class="hlt">hydrothermal</span> route using NH4VO3 as precursor in the presence of sulfuric acid at 120°C for 24 h. This synthesis process is free of any templates and reducing agents. Thermal analysis showed a phase change at 350°C and the samples were annealed at 500°C. The XRD analysis showed the monoclinic phase for the as-prepared and orthorhombic phase of V2O5 when annealed at 500°C. Characteristic Raman peaks also expressed the same structural features. Microstructure analysis by SEM showed the nanowire structure of V2O5 with thickness in the range of 20-50 nm and length in micrometers. The possible mechanisms of formation of the nanowires were schematically explained based on the layered structure of V2O5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27467200','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27467200"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Gelation of Aqueous Cellulose Nanocrystal Suspensions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lewis, Lev; Derakhshandeh, Maziar; Hatzikiriakos, Savvas G; Hamad, Wadood Y; MacLachlan, Mark J</p> <p>2016-08-01</p> <p>We report the facile preparation of gels from the <span class="hlt">hydrothermal</span> treatment of suspensions of cellulose nanocrystals (CNCs). The properties of the hydrogels have been investigated by rheology, electron microscopy, and spectroscopy with respect to variation in the temperature, time, and CNC concentration used in preparation. Desulfation of the CNCs at high temperature appears to be responsible for the gelation of the CNCs, giving highly porous networks. The viscosity and storage modulus of the gels was shown to increase when samples were prepared at higher treatment temperature. Considering the wide natural abundance and biocompatibility of CNCs, this simple, green approach to CNC-based hydrogels is attractive for producing materials that can be used in drug delivery, insulation, and as tissue scaffolds. PMID:27467200</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014633','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014633"><span id="translatedtitle">CONCEPTUAL MODELS FOR THE LASSEN <span class="hlt">HYDROTHERMAL</span> SYSTEM.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ingebritsen, S.E.; Sorey, M.L.</p> <p>1987-01-01</p> <p>The Lassen <span class="hlt">hydrothermal</span> system, like a number of other systems in regions of moderate to great topographic relief, includes steam-heated features at higher elevations and high-chloride springs at lower elevations, connected to and fed by a single circulation system at depth. Two conceptual models for such systems are presented. They are similar in several ways: however, there are basic differences in terms of the nature and extent of vapor-dominated conditions beneath the steam-heated features. For some Lassen-like systems, these differences could have environmental and economic implications. Available data do not make it possible to establish a single preferred model for the Lassen system, and the actual system is complex enough that both models may apply to different parts of the system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080047210','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080047210"><span id="translatedtitle">Deep-Sea <span class="hlt">Hydrothermal</span>-Vent Sampler</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Behar, Alberto E.; Venkateswaran, Kasthur; Matthews, Jaret B.</p> <p>2008-01-01</p> <p>An apparatus is being developed for sampling water for signs of microbial life in an ocean <span class="hlt">hydrothermal</span> vent at a depth of as much as 6.5 km. Heretofore, evidence of microbial life in deep-sea <span class="hlt">hydrothermal</span> vents has been elusive and difficult to validate. Because of the extreme conditions in these environments (high pressures and temperatures often in excess of 300 C), deep-sea <span class="hlt">hydrothermal</span>- vent samplers must be robust. Because of the presumed low density of biomass of these environments, samplers must be capable of collecting water samples of significant volume. It is also essential to prevent contamination of samples by microbes entrained from surrounding waters. Prior to the development of the present apparatus, no sampling device was capable of satisfying these requirements. The apparatus (see figure) includes an intake equipped with a temperature probe, plus several other temperature probes located away from the intake. The readings from the temperature probes are utilized in conjunction with readings from flowmeters to determine the position of the intake relative to the <span class="hlt">hydrothermal</span> plume and, thereby, to position the intake to sample directly from the plume. Because it is necessary to collect large samples of water in order to obtain sufficient microbial biomass but it is not practical to retain all the water from the samples, four filter arrays are used to concentrate the microbial biomass (which is assumed to consist of particles larger than 0.2 m) into smaller volumes. The apparatus can collect multiple samples per dive and is designed to process a total volume of 10 L of vent fluid, of which most passes through the filters, leaving a total possibly-microbe-containing sample volume of 200 mL remaining in filters. A rigid titanium nose at the intake is used for cooling the sample water before it enters a flexible inlet hose connected to a pump. As the water passes through the titanium nose, it must be cooled to a temperature that is above a mineral</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5752591','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5752591"><span id="translatedtitle">Methane and radioactive isotopes in submarine <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, K.R.</p> <p>1983-01-01</p> <p>This thesis consists of two parts: 1) methane and 2) radioactive isotopes, especially radon, in submarine <span class="hlt">hydrothermal</span> systems. Both parts deal with the use of these gases as tracers for mapping <span class="hlt">hydrothermal</span> vents at sea, and with their relationships to other sensitive tracers such as helium, manganese, and temperature. <span class="hlt">Hydrothermal</span> methane was used as a real-time tracer for locating new submarine <span class="hlt">hydrothermal</span> systems along spreading axes, discovering new <span class="hlt">hydrothermal</span> systems at two locations in Pacific Ocean: 1) 20/sup 0/S on East Pacific Rise, and 2) Mariana Trough Back-arc Basin. Methane shows good correlations with helium-3 and temperature with similar ratios in various <span class="hlt">hydrothermal</span> systems, 3 to 42 x 10/sup 6/ for the methane to helium-3 ratio, and 3 to 19 ..mu.. cc/kg/sup 0/C for the methane to temperature anomaly. These similar ratios from different areas provide evidence for chemical homogeneity of submarine <span class="hlt">hydrothermal</span> waters. A good correlation between methane and manganese appears to be associated only with high-temperature <span class="hlt">hydrothermal</span> systems. Radioisotopes in the vent waters of 21/sup 0/N high-temperature <span class="hlt">hydrothermal</span> system have end-member concentrations of 7.5 to 40 dpm/kg for Ra-226, 360 dpm/kg for Rn 222, 62 dpm/kg for Pb-210, and 19 dpm/kg for Po-210. The radon activity for this system is one order of magnitude lower, and the Pb-210 activity is one order or magnitude higher, than those a the low temperature Galapagos system. All these observations suggest that the high radon, and low Pb-210 activity observed in Galapagos system may originate from the extensive subsurface mixing and water-rock interaction in this system (direct injection of radon and scavenging of Pb-210).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.B13B0463C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.B13B0463C&link_type=ABSTRACT"><span id="translatedtitle">Microbial Activity and Volatile Fluxes in Seafloor <span class="hlt">Hydrothermal</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Corrigan, R. S.; Lowell, R. P.</p> <p>2013-12-01</p> <p>Understanding geographically and biologically the production or utilization of volatile chemical species such as CO2, CH4, and H2 is crucial not only for understanding <span class="hlt">hydrothermal</span> processes but also for understanding life processes in the oceanic crust. To estimate the microbial effect on the transport of these volatiles, we consider a double-loop single pass model as shown in Figure 1 to estimate the mass fluxes shown. We then use a simple mixing formulation: C4Q4 = C3 (Q1 -Q3)+ C2Q2, where C2 is the concentration of the chemical in seawater, C3 is the average concentration of the chemical in high temperature focused flow, C4 is the expected concentration of the chemical as a result of mixing, and the relevant mass flows are as shown in Figure 1. Finally, we compare the calculated values of CO2, CH4, and H2 in diffuse flow fluids to those observed. The required data are available for both the Main Endeavour Field on the Juan de Fuca Ridge and the East Pacific Rise 9°50' N systems. In both cases we find that, although individual diffuse flow <span class="hlt">sites</span> have observed concentrations of some elements that are greater than average, the average concentration of these volatiles is smaller in all cases than the concentration that would be expected from simple mixing. This indicates that subsurface microbes are net utilizers of these chemical constituents at the Main Endeavour Field and at EPR 9°50' N on the vent field scale. Figure 1. Schematic of a 'double-loop' single-pass model above a convecting, crystallizing, replenished AMC (not to scale). Heat transfer from the vigorously convecting, cooling, and replenished AMC across the conductive boundary layer δ drives the overlying <span class="hlt">hydrothermal</span> system. The deep circulation represented by mass flux Q1 and black smoker temperature T3 induces shallow circulation noted by Q2. Some black smoker fluid mixes with seawater resulting in diffuse discharge Q4, T4, while the direct black smoker mass flux with temperature T3 is reduced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15802678','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15802678"><span id="translatedtitle">Influence of environmental conditions on early development of the <span class="hlt">hydrothermal</span> vent polychaete Alvinella pompejana.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pradillon, Florence; Le Bris, Nadine; Shillito, Bruce; Young, Craig M; Gaill, Françoise</p> <p>2005-04-01</p> <p>Dispersal and colonisation processes at deep-sea vents are still not fully understood, essentially because early life stages of vent species remain unknown. The polychaete worm Alvinella pompejana forms colonies on chimney walls at East Pacific Rise vent <span class="hlt">sites</span> where the temperature can frequently exceed 20 degrees C. In vitro studies in pressure vessels showed that the early embryos tolerate temperatures in a lower range (10-14 degrees C), suggesting that they would have to escape the colony to develop. Pressure vessels offer the advantage that each parameter can be independently controlled, but they do not simulate the more complex and dynamic conditions naturally encountered at vent <span class="hlt">sites</span>. Accordingly, in addition to incubations in pressure vessels, we incubated embryos directly at a vent <span class="hlt">site</span>, in different habitats along a gradient of <span class="hlt">hydrothermal</span> influence. Embryos incubated on an adult A. pompejana colony where temperature and H(2)S concentrations were relatively high showed a very low survival rate and did not develop, whereas embryos incubated in a Riftia pachyptila clump environment with a lower <span class="hlt">hydrothermal</span> signature, or at the base of the chimney where the influence of the <span class="hlt">hydrothermal</span> activity was very weak, survived well and developed. Although the average temperature recorded in the A. pompejana colony was within the range tolerated by embryos (13 degrees C), frequent peaks above 20 degrees C were recorded. Estimated sulphide concentration at this <span class="hlt">site</span> reached 200 mumol l(-1). Punctuated exposure to both high temperature and elevated sulphide levels probably explain the low survival of embryos within the A. pompejana colony. The in situ experiments further support the idea that embryos require conditions with moderate <span class="hlt">hydrothermal</span> influence not generally found within an adult colony. However, as much more benign physicochemical conditions can be found within a few tens of cm of adult colonies, embryos do not necessarily have to leave their vent of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022773','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022773"><span id="translatedtitle">Permeability reduction in granite under <span class="hlt">hydrothermal</span> conditions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morrow, C.A.; Moore, Diane E.; Lockner, D.A.</p> <p>2001-01-01</p> <p>The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under <span class="hlt">hydrothermal</span> conditions. In this study, permeability measurements were conducted on intact, fractured, and gouge-bearing Westerly granite at an effective pressure of 50 MPa and at temperatures from 150?? to 500??C, simulating conditions in the earthquake-generating portions of fault zones. Pore fluids were cycled back and forth under a 2 MPa pressure differential for periods of up to 40 days. Permeability of the granite decreased with time t, following the exponential relation k = c(10-rt). For intact samples run between 250?? and 500??C the time constant for permeability decrease r was proportional to temperature and ranged between 0.001 and 0.1 days-1 (i.e., between 0.4 and 40 decades year-1 loss of permeability). Values of r for the lower-temperature experiments differed little from the 250??C runs. In contrast, prefractured samples showed higher rates of permeability decrease at a given temperature. The surfaces of the fractured samples showed evidence of dissolution and mineral growth that increased in abundance with both temperature and time. The experimentally grown mineral assemblages varied with temperature and were consistent with a rock-dominated <span class="hlt">hydrothermal</span> system. As such mineral deposits progressively seal the fractured samples, their rates of permeability decrease approach the rates for intact rocks at the same temperature. These results place constraints on models of precipitation sealing and suggest that fault rocks may seal at a rate consistent with earthquake recurrence intervals of typical fault zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.632F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.632F"><span id="translatedtitle">Peptide synthesis under Enceladus <span class="hlt">hydrothermal</span> condition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujishima, Kosuke; Takano, Yoshinori; Takai, Ken; Takahagi, Wataru; Adachi, Keito; Shibuya, Takazo; Tomita, Masaru</p> <p>2016-07-01</p> <p>Enceladus is one of the moons of Saturn, and it has been known to harbor interior ocean beneath the icy crust. The mass spectrometry data obtained by Cassini spacecraft indicates the presence of salty, and most likely alkaline ocean containing various organic compounds. While geochemical and other radiation related processes for in situ production of organics remain elusive, thermally unaltered carbonaceous chondrites, consisting the main body of Enceladus are known to be enriched with organic matters potentially including the building blocks of life (e.g., amino acids and amino acid precursors). Assuming that abiotic amino acids exist in the Enceladus alkaline seawater, we hypothesized that water-rock interaction may contribute to condensation of localized amino acids leading to peptide formation. In order to test this hypothesis, we have developed the Enceladus <span class="hlt">hydrothermal</span> reactor based on the chemical constraints obtained through previous experimental and theoretical studies. We have added six different amino acids and introduced a thermal fluctuation system simulating the periodic tidal heating of the interior chondritic core. Total, eight sea water samples were obtained over the course of 147 days of experiment. While detection of peptide using Capillary Electrophoresis Time-of-Flight Mass Spectrometry (CE-TOF/MS) is still at the preliminary stage, so far pH monitoring and H2 and CO2 Gas Chromatography Mass Spectrometry (GC-MS) data clearly indicated the occurrence of serpentinization/carbonation reaction. Here, we discuss the interaction between aqueous alteration reactions and thermal cycling processes for the role of abiotic peptide formation under the Enceladus <span class="hlt">hydrothermal</span> condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP11A..07F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP11A..07F"><span id="translatedtitle">Absolute Magnetization Distribution on Back-arc Spreading Axis Hosting <span class="hlt">Hydrothermal</span> Vents; Insight from Shinkai 6500 Magnetic Survey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, M.; Okino, K.; Honsho, C.; Mochizuki, N.; Szitkar, F.; Dyment, J.</p> <p>2013-12-01</p> <p>Near-bottom magnetic profiling using submersible, deep-tow, Remotely Operated Vehicle (ROV) and Autonomous Underwater Vehicle (AUV) make possible to conduct high-resolution surveys and depict detailed magnetic features reflecting, for instance, the presence of fresh lavas or <span class="hlt">hydrothermal</span> alteration, or geomagnetic paleo-intensity variations. We conducted near-bottom three component magnetic measurements onboard submersible Shinkai 6500 in the Southern Mariana Trough, where five active <span class="hlt">hydrothermal</span> vent fields (Snail, Yamanaka, Archean, Pica, and Urashima <span class="hlt">sites</span>) have been found in both on- and off-axis areas of the active back-arc spreading center, to detect signals from <span class="hlt">hydrothermally</span> altered rock and to distinguish old and new submarine lava flows. Fourteen dives were carried out at an altitude of 1-40 m during the R/V Yokosuka YK10-10 and YK10-11 cruises in 2010. We carefully corrected the effect of the induced and permanent magnetizations of the submersible by applying the correction method for the shipboard three-component magnetometer measurement modified for deep-sea measurement, and subtracted the IGRF values from the corrected data to obtain geomagnetic vector anomalies along the dive tracks. We then calculated the synthetic magnetic vector field produced by seafloor, assumed to be uniformly magnetized, using three dimensional forward modeling. Finally, values of the absolute magnetizations were estimated by using a linear transfer function in the Fourier domain from the observed and synthetic magnetic anomalies. The distribution of estimated absolute magnetization generally shows low values around the five <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span>. This result is consistent with the equivalent magnetization distribution obtained from previous AUV survey data. The areas of low magnetization are also consistent with <span class="hlt">hydrothermal</span> deposits identified in video records. These results suggest that low magnetic signals are due to <span class="hlt">hydrothermal</span> alteration zones where host rocks are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13A1696Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1696Y"><span id="translatedtitle">Structural and functional diversity of microbial communities beneath the <span class="hlt">hydrothermal</span> vent at the Iheya North field of the Mid-Okinawa Trough (IODP Expedition 331)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yanagawa, K.; Nunoura, T.; Kawagucci, S.; Hirai, M.; Sunamura, M.; Breuker, A.; Brandt, L.; House, C. H.; McAllister, S. M.; Moyer, C. L.; Takai, K.</p> <p>2012-12-01</p> <p>Complex and diverse microbial communities in deep-sea <span class="hlt">hydrothermal</span> fluids are apparently different from those in ambient seawater, some of which are predicted to migrate along <span class="hlt">hydrothermal</span> vein from "subvent biosphere". Subseafloor environment just beneath active <span class="hlt">hydrothermal</span> vent has been expected to be one of the most conceivable habitats for metabolically active and diverse microbial community. We conducted the scientific ocean drilling (IODP Expedition 331) for the Iheya North <span class="hlt">hydrothermal</span> field in the Mid-Okinawa Trough in Sept. 2010, and collected core samples from the subseafloor biosphere beneath the <span class="hlt">hydrothermal</span> vent. IODP <span class="hlt">Site</span> C0014 was located 450 m east off the main <span class="hlt">hydrothermal</span> vent. Temperature exceeded the limit of life at the depth of approximately 40 m below the seafloor. Both microscopy and quantitative PCR analyses successfully detected microbial populations in the shallower zone above 15 mbsf. However, the cultivation attempts of (hyper-)thermophiles were unsuccessful all over the depth. Culture-independent molecular biological experiments showed that microbial community composition distinctly changed with depth, possibly because of physicochemical conditions such as methane, sulfate and temperature. Microbial activities of methanogenesis and anaerobic methane oxidation were in accordance with the geochemical profiles of methane and sulfate. These results indicated the presence of functionally active subseafloor microbial communities but those were different from expected members in subvent biosphere. <span class="hlt">Site</span> C0017 located 1.6 km east off the <span class="hlt">hydrothermal</span> vent is a potential seawater recharge zone of the <span class="hlt">hydrothermal</span> system, where seawater penetrates into the oceanic crust. The lithostratigraphy consists of characteristic coarse angular pumiceous gravel, lying above and below hemipelagic mud, in which high permeability may allow entrainment of seawater. As is the case with sedimentary subsurface environments, uncultivated archaeal groups were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B13A0172B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B13A0172B"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Mineral Deposits From a Young (0.1Ma) Abyssal Hill on the Flank of the Fast-Spreading East Pacific Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benjamin, S. B.; Haymon, R. M.</p> <p>2004-12-01</p> <p>It has been estimated from heat flow measurements that at least 40% of the total <span class="hlt">hydrothermal</span> heat lost from oceanic lithosphere is removed from 0.1-5 Ma abyssal hill terrain on mid-ocean ridge flanks. Despite the large magnitude of estimated <span class="hlt">hydrothermal</span> heat loss from young abyssal hills, little is known about characteristics of <span class="hlt">hydrothermal</span> vents and mineral deposits in this setting. This study describes the first abyssal hill <span class="hlt">hydrothermal</span> samples to be collected on the flank of a fast-spreading ridge. The mineral deposits were discovered at "Tevnia <span class="hlt">Site</span>" on the axis-facing fault scarp of an abyssal hill, located on ˜0.1 Ma lithosphere ˜5 km east of the East Pacific Rise (EPR) axis at 10\\deg 20'N. Observations of Galatheid crabs, "dandelion" siphonophores, and colonies of dead, yet still intact, Tevnia worm tubes at this <span class="hlt">site</span> during Alvin dives in 1994 suggests relatively recent <span class="hlt">hydrothermal</span> activity. The deposits are friable <span class="hlt">hydrothermal</span> precipitates incorporating volcanic clasts brecciated at both the micro and macro scales. The petrographic sequence of brecciation, alteration, and cementation exhibited by the samples suggests that they formed from many pulses of <span class="hlt">hydrothermal</span> venting interspersed with, and perhaps triggered by, repeated tectonic events as the abyssal hill was uplifted and moved off-axis (see also Haymon et al., this session). Observed minerals include x-ray amorphous opaline silica and Fe-oxide phases, crystalline Mn-oxides (birnessite and todorokite), an irregularly stratified mixed layer nontronite-celadonite, and residual calcite in sediment-derived microfossils incorporated into the breccia matrix. This mineral assemblage suggests that the deposits precipitated from moderately low-temperature (<140\\deg C) fluids, enriched in K, Fe, Si, and Mn, with a near-neutral pH. The presence of tubeworm casings at the <span class="hlt">site</span> is evidence that the <span class="hlt">hydrothermal</span> fluids carried H2S, however no metal sulfide phases were identified in the samples. Although</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5719973','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5719973"><span id="translatedtitle">Metals and isotopes in Juan de Fuca Ridge <span class="hlt">hydrothermal</span> fluids and their associated solid materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hinkley, T.K.; Tatsumoto, M.</p> <p>1987-10-10</p> <p>The /sup 87/Sr//sup 86/Sr ratio of the <span class="hlt">hydrothermal</span> solution (HTS) (0.7034) is larger than that of basalt (0.7025) at the southern vent field of the Juan de Fuca Ridge (SJFR). Both the Sr isotopic ratio for HTS and the water/rock interaction ratio lie between those at two <span class="hlt">sites</span> farther south on the East Pacific Rise, 13 /sup 0/N and 21 /sup 0/N. These parameters may be closely related to subsurface temperatures and rates of magma ascent and to extent of faulting and surface areas of the frameworks of the <span class="hlt">hydrothermal</span> systems. For these three Pacific Ocean <span class="hlt">sites</span> there is no steady geographical progression of these measured parameters, nor of reported spreading rate, with increasing latitude northward. Pb and Nd isotopic measurements are uniform for all samples from the SJFR, ranging only from 18.43 to 18.58 for /sup 206/Pb//sup 204/Pb (fluids and associated solids) and centering near 0.5131 for /sup 143/Nd//sup 144/Nd (only fluids measured). Values for basalts and sulfides from the <span class="hlt">site</span> have similar values. Relatively high /sup 206/Pb//sup 204/Pb values at the SJFR suggest the potential for the existence of an anomalous radiogenic heat source in the underlying mantle material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26375668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26375668"><span id="translatedtitle">Microbial diversity in deep-sea sediments from the Menez Gwen <span class="hlt">hydrothermal</span> vent system of the Mid-Atlantic Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cerqueira, Teresa; Pinho, Diogo; Egas, Conceição; Froufe, Hugo; Altermark, Bjørn; Candeias, Carla; Santos, Ricardo S; Bettencourt, Raul</p> <p>2015-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> sediments are known to support remarkably diverse microbial consortia. Cultureindependent sequence-based technologies have extensively been used to disclose the associated microbial diversity as most of the microorganisms inhabiting these ecosystems remain uncultured. Here we provide the first description of the microbial community diversity found on sediments from Menez Gwen vent system. We compared <span class="hlt">hydrothermally</span> influenced sediments, retrieved from an active vent chimney at 812 m depth, with non-<span class="hlt">hydrothermally</span> influenced sediments, from a 1400 m depth bathyal plain. Considering the enriched methane and sulfur composition of Menez Gwen vent fluids, and the sediment physicochemical properties in each sampled area, we hypothesized that the <span class="hlt">site</span>-associated microbes would be different. To address this question, taxonomic profiles of bacterial, archaeal and micro-eukaryotic representatives were studied by rRNA gene tag pyrosequencing. Communities were shown to be significantly different and segregated by sediment geograp