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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. Hydrothermal Alteration in the Logatchev Hydrothermal Field: Implications From Secondary Mineral Assemblages and Mineral Chemistry

    NASA Astrophysics Data System (ADS)

    Lackschewitz, K. S.; Augustin, N.; Devey, C. W.; Eisenhauer, A.; Garbe-Schoenberg, D.; James, R.

    2005-12-01

    We present new data on secondary mineral assemblages, clay and whole rock chemistry and clay mineral strontium and lithium isotopic compositions of altered rocks and sediments from the active, ultramafic-hosted Logatchev hydrothermal field reflecting various alteration conditions (e.g. fluid mixing, water-rock interaction). The altered ultramafic rocks are mainly consist of lizardite, chrysotile whereas magnetite and pyrite are minor minerals. Chlorite, chlorite-smectite mixed-layer (e.g., corrensite), smectite and talc are additional common phases in the clay fraction of most of these samples.Iron-hydroxides and iron sulfides are the main components of the hydrothermal crusts, with some amounts of pyroxene, chlorite, illite and pyrite. The hydrothermal sediments beneath the crusts are characterized by quartz, smectite and chlorite as main minerals. Analyses of clay separates representing a variety of alteration styles demonstrates that significant and characteristic changes in the bulk rock chemical composition are associated with various alteration conditions. The elements Cr, Cu, Pb and U appears to have a general enrichment in the lizardite and chlorite concentrates in comparison to a depleted mantle. 87Sr/86Sr ratios of clay concentrates vary between 0.7083 and 0.7096 suggesting that the clays either formed as a result of seawater alteration or hydrothermal alteration with various portions of seawater. The strontium isotopic ratio of a chlorite sample from hydrothermal sediments beneath the hydrothermal crust is much lower than the isotopic data reported for the lizardites suggesting precipitation from fluid with lower seawater content. The Li isotopic composition (δ7Li) of the clay separates varies between -5.4 and +6.4‰. Thus, the clays are enriched in 6Li relative to both seawater (~31‰) and hydrothermal vent fluids from the Logatchev field (~6‰) suggesting that 6Li is preferentially retained in alteration products. When considered together with the

  4. Long term ocean bottom pressure monitoring in the Logatchev Hydrothermal Field - indications for tremor, earthquakes, uplift and subsidence

    NASA Astrophysics Data System (ADS)

    Gennerich, H.-H.; Villinger, H.

    2009-04-01

    The mid oceanic spreading axes are centers of recent ore generation, accommodate little known chemotropic biological communities, 90 per cent of the global volcanism and contribute 25 per cent of the heat released from the earth. But little is known about these systems because their location in the depth of the oceans and much less about their changes in time. Target of a joint multidisciplinary approach to learn more about the temporal variations of a hydrothermal field has been the Logatchev Hydrothermal Field (LHF) at the Mid Atlantic Ridge in the framework of the SPP1144 of the German Research Foundation. It was chosen because of its high representativity with its moderate spreading rate, the mixture of basaltic and mantle rocks in the subsurface and its pronounced bathymetric relief. In the Logatchev Hydrothermal Field (LHF) hydrothermal activity is observed at several distinct sites. Focussed high-temperature outlets at black smokers were found as well as diffuse warm water outflow. Four locations in the LHF were equipped with instruments, to monitor physical parameters for about one year. At "OBP-site" an ocean-bottom-pressure-meter (OBP) and an ocean-bottom-tilt-meter (OBT) were installed, monitoring water pressure, temperature as well as the sea floor inclination. At "Mooring-site" a sensor chain scanned the temperatures of the bottom water every 6 minutes in 1 m intervals, from the sea floor to 25 m vertically above. The adjoining mussel fields Quest and Irina2 were instrumented with 12 temperature loggers each, registering the temperatures. In this poster data of the long term ocean bottom pressure monitoring are presented and discussed in context with temperature data regarding their meaning for tectonic processes. Earthquakes and very low frequency tremor activity are recognized. Temperature monitoring and CTD measurements help to separate sea floor uplift and subsidence from oceanographic signals.

  5. 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

  6. 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

  7. Calcium isotope (δ 44/40Ca) fractionation along hydrothermal pathways, Logatchev field (Mid-Atlantic Ridge, 14°45'N)

    NASA Astrophysics Data System (ADS)

    Amini, Marghaleray; Eisenhauer, Anton; Böhm, Florian; Fietzke, Jan; Bach, Wolfgang; Garbe-Schönberg, Dieter; Rosner, Martin; Bock, Barbara; Lackschewitz, Klas S.; Hauff, Folkmar

    2008-08-01

    We investigate the Logatchev Hydrothermal Field at the Mid-Atlantic Ridge, 14°45'N to constrain the calcium isotope hydrothermal flux into the ocean. During the transformation of seawater to a hydrothermal solution, the Ca concentration of pristine seawater ([Ca] SW) increases from about 10 mM to about 32 mM in the hydrothermal fluid endmember ([Ca] HydEnd) and thereby adopts a δ 44/40Ca HydEnd of -0.95 ± 0.07‰ relative to seawater (SW) and a 87Sr/ 86Sr isotope ratio of 0.7034(4). We demonstrate that δ 44/40Ca HydEnd is higher than that of the bedrock at the Logatchev field. From mass balance calculations, we deduce a δ 44/40Ca of -1.17 ± 0.04‰ (SW) for the host-rocks in the reaction zone and -1.45 ± 0.05‰ (SW) for the isotopic composition of the entire hydrothermal cell of the Logatchev field. The values are isotopically lighter than the currently assumed δ 44/40Ca for Bulk Earth of -0.92 ± 0.18‰ (SW) [Skulan J., DePaolo D. J. and Owens T. L. (1997) Biological control of calcium isotopic abundances in the global calcium cycle. Geochim. Cosmochim. Acta61,(12) 2505-2510] and challenge previous assumptions of no Ca isotope fractionation between hydrothermal fluid and the oceanic crust [Zhu P. and Macdougall J. D. (1998) Calcium isotopes in the marine environment and the oceanic calcium cycle. Geochim. Cosmochim. Acta62,(10) 1691-1698; Schmitt A. -D., Chabeaux F. and Stille P. (2003) The calcium riverine and hydrothermal isotopic fluxes and the oceanic calcium mass balance. Earth Planet. Sci. Lett. 6731, 1-16]. Here we propose that Ca isotope fractionation along the fluid flow pathway of the Logatchev field occurs during the precipitation of anhydrite. Two anhydrite samples from the Logatchev Hydrothermal Field show an average fractionation of about Δ 44/40Ca = -0.5‰ relative to their assumed parental solutions. Ca isotope ratios in aragonites from carbonate veins from ODP drill cores indicate aragonite precipitation directly from seawater at low

  8. In situ measurements of hydrogen sulfide, oxygen, and temperature in diffuse fluids of an ultramafic-hosted hydrothermal vent field (Logatchev, 14°45‧N, Mid-Atlantic Ridge): Implications for chemosymbiotic bathymodiolin mussels

    NASA Astrophysics Data System (ADS)

    Zielinski, Frank U.; Gennerich, Hans-Hermann; Borowski, Christian; WenzhöFer, Frank; Dubilier, Nicole

    2011-09-01

    The Logatchev hydrothermal vent field (14°45'N, Mid-Atlantic Ridge) is located in a ridge segment characterized by mantle-derived ultramafic outcrops. Compared to basalt-hosted vents, Logatchev high-temperature fluids are relatively low in sulfide indicating that the diffuse, low-temperature fluids of this vent field may not contain sufficient sulfide concentrations to support a chemosymbiotic invertebrate community. However, the high abundances of bathymodiolin mussels with bacterial symbionts related to free-living sulfur-oxidizing bacteria suggested that bioavailable sulfide is present at Logatchev. To clarify, if diffuse fluids above mussel beds of Bathymodiolus puteoserpentis provide the reductants and oxidants needed by their symbionts for aerobic sulfide oxidation, in situ microsensor measurements of dissolved hydrogen sulfide and oxygen were combined with simultaneous temperature measurements. High temporal fluctuations of all three parameters were measured above the mussel beds. H2S and O2 coexisted with mean concentrations between 9 and 31 μM (H2S) and 216 and 228 μM (O2). Temperature maxima (≤7.4°C) were generally concurrent with H2S maxima (≤156 μM) and O2 minima (≥142 μM). Long-term measurements for 250 days using temperature as a proxy for oxygen and sulfide concentrations indicated that the mussels were neither oxygen limited nor sulfide limited. Our in situ measurements at Logatchev indicate that sulfide may also be bioavailable in diffuse fluids from other ultramafic-hosted vents along slow and ultraslow spreading ridges.

  9. 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

  10. 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.

  11. 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.

  12. Identifying Martian Hydrothermal Sites: Geological Investigation Utilizing Multiple Datasets

    NASA Technical Reports Server (NTRS)

    Dohm, J. M.; Baker, V. R.; Anderson, R. C.; Scott, D. H.; Rice, J. W., Jr.; Hare, T. M.

    2000-01-01

    Comprehensive geological investigations of martian landscapes that may have been modified by magmatic-driven hydrothermal activity, utilizing multiple datasets, will yield prime target sites for future hydrological, mineralogical, and biological investigations.

  13. Hydrothermal Fluxes at the Turtle Pits Vent Site, southern MAR

    NASA Astrophysics Data System (ADS)

    Köhler, J.; Walter, M.; Mertens, C.; Sültenfuß, J.; Rhein, M.

    2009-04-01

    The Turtle Pits vent fields are located in a north-south orientated rift valley at the Mid-Atlantic Ridge (MAR) near 5oS. The site consists of three known hydrothermal fields: Turtle Pits, Comfortless Cove, and Red Lion. Data collected during a Meteor cruise in May 2006 and a L' Atalante cruise in January 2008 are used to calculate the total emission of volume, heat, and helium of the site. The data sets consist of vertical profiles and towed transsects of temperature, salinity, and turbidity, as well as direct velocity measurements with a lowered acoustic Doppler current profiler (LADCP) and water samples for Helium isotope analysis. Vent fluid samples for noble gas analysis where taken with an ROV. The particle plume is confined to the rift valley since the depth of the valley exceeds the rise height of the plume. Therefore the fluxes of heat and volume can be estimated from the helium fluxes at the vent sites in comparison with the horizontal helium transport in the valley. The comparison of the 3He concentration measured south of the hydrothermal vents with the 3He signal north of the hydrothermal vents suggests a rather strong northward flow. This is confirmed by the tide corrected velocities observed with the LADCP during the Meteor cruise. The northward volume transport has been calculated using the local bathymetry and tide corrected velocities from the Meteor cruise. In combination with the 3He concentrations and an average 3He end member concentration a flux of 900 l/s is estimated, which corresponds to a heat flux of 450 MW. The rise height of the particle plume estimated from the turbidity data combined with the known background stratification yields an estimate of the total flux of the hydrothermal vents which is one order of magnitude lower.

  14. What causes low magnetization at basalt-hosted hydrothermal sites? Insights from inactive site Krasnov (MAR 16°38'N)

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    magnetic surveys acquired near the seafloor show that active basalt-hosted hydrothermal sites are associated with zones of lower magnetization. This observation may reflect the thermal demagnetization of a hot hydrothermal zone, the alteration of basalt affected by hydrothermal circulation, and/or the presence of thick, nonmagnetic hydrothermal deposits. In order to discriminate among these inferences, we acquired vector magnetic data 50 m above inactive hydrothermal site Krasnov using the Remotely Operated Vehicle (ROV) Victor. This deep hydrothermal site, located 7 km east of the Mid-Atlantic Ridge (MAR) axis at 16°38'N, is dissected by major normal faults and shows no evidence of recent hydrothermal activity. It is therefore a perfect target for investigating the magnetic signature of an inactive basalt-hosted hydrothermal site. Krasnov exhibits a strong negative magnetic anomaly, which implies that the lower magnetization observed at basalt-hosted hydrothermal sites is not a transient effect associated with hydrothermal activity, but remains after activity ceases. Thermal demagnetization plays only a secondary role, if any, in the observed magnetic low. Forward models suggest that both the nonmagnetic hydrothermal deposits and an altered zone of demagnetized basalt are required to account for the observed magnetic low. The permanence of this magnetic signature makes it a useful tool to explore midocean ridges and detect inactive hydrothermal sites.

  15. Discovery of new hydrothermal vent sites in Bransfield Strait, Antarctica

    NASA Astrophysics Data System (ADS)

    Klinkhammer, G. P.; Chin, C. S.; Keller, R. A.; Dählmann, A.; Sahling, H.; Sarthou, G.; Petersen, S.; Smith, F.; Wilson, C.

    2001-12-01

    We carried out a search for hydrothermal vents in the Central Basin of Bransfield Strait, Antarctica. The ZAPS (zero angle photon spectrometer) chemical sensor and instrument package (Oregon State University), OFOS (ocean-floor observation system) camera sled and TVG (TV-grab) (GEOMAR) were used to explore the water column and underlying seafloor. These operations were supplemented with a series of dredges. Hydrothermal plumes over Hook Ridge at the eastern end of the basin are confined to the E ridge crest and SE flank. The plumes are complex and sometimes contain two turbidity maxima one widespread feature centered at 1150 m and a smaller, more localized but broad maximum at 600-800 m. We traced the source of the shallower plume to a sunken crater near the ridge crest using sensors on the ZAPS instrument package. Subsequently two TV-grabs from the crater brought back hot, soupy sediment (42-49°C) overlain by hard, siliceous crusts and underlain by a thick layer of volcanic ash. We also recovered chimney fragments whose texture and mineralogy indicate venting temperatures in excess of 250°C. Native sulfur and Fe-sulfides occur in fractures and porous layers in sediment from throughout the area. Pore water data from the crater site are consistent with venting into a thin sediment layer and indicate phase separation of fluids beneath Hook Ridge. The source of the deeper plumes at Hook Ridge has yet to be located. We also explored a series of three parallel volcanic ridges west of Hook Ridge called Three Sisters. We detected water column anomalies indicative of venting with the ZAPS package and recovered hydrothermal barites and sulfides from Middle Sister. We spent considerable time photographing Middle Sister and Hook Ridge but did not identify classic vent fauna at either location. We either missed small areas with our photography or typical MOR vent fauna are absent at these sites.

  16. 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

  17. Ambient light emission from hydrothermal vents on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    White, Sheri N.; Chave, Alan D.; Reynolds, George T.; Van Dover, Cindy L.

    2002-08-01

    A spectral imaging camera was used to observe light emission from high-temperature, deep-sea vents at three hydrothermal sites on the Mid-Atlantic Ridge (MAR): Logatchev, Snake Pit, and Lucky Strike. Ambient light measured at these sites is similar to that observed at sites along the East Pacific Rise and the Juan de Fuca Ridge, with components from both thermal and non-thermal sources. The shrimp species Rimicaris exoculata, which is found on the MAR but not in the Eastern Pacific, possesses a unique photoreceptor capable of detecting low light levels. It is not yet known if R. exoculata ``sees'' vent light. However, since the characteristics of vent light appear to be unrelated to geographical location, the exclusion of R. exoculata from the Eastern Pacific is probably unrelated to differences in ambient light conditions.

  18. Characteristics and source of inorganic and organic compounds in the sediments from two hydrothermal fields of the Central Indian and Mid-Atlantic Ridges

    NASA Astrophysics Data System (ADS)

    Peng, Xiaotong; Li, Jiwei; Zhou, Huaiyang; Wu, Zijun; Li, Jiangtao; Chen, Shun; Yao, Huiqiang

    2011-05-01

    A combined inorganic and organic geochemical study was carried out on sediments collected from the Kairei hydrothermal field on the Central Indian Ridge (CIR) and the Logatchev hydrothermal field on the Mid Atlantic Ridge (MAR). Analysis of the major and trace elements as well as the minerals shows that the Kairei hydrothermal sediments are formed by the mixing of silica-rich hydrothermal fluids with Mg-rich seawaters, but the Logatchev sediments are associated with pelagic carbonate oozes containing some precipitates derived from hydrothermal plume fall-out. The rare earth element (REE) patterns of Kairei sediments show a character of light REE (LREE) enrichment and positive Eu anomaly, whereas two of the three Logatchev sediment samples lack positive Eu anomaly and have negative Ce anomaly. Patterns of aliphatic hydrocarbon fractions in the sediments from both hydrothermal fields exhibit high relative concentrations of volatile resolved components, smooth n-alkane distributions and high concentrations of the isoprenoids pristane and phytane. The composition of organic matter and C isotope composition of individual n-alkanes indicate that they come from marine photosynthetic autotrophs and hydrothermal organisms, as well as terrestrial inputs in the Kairei and the Logatchev hydrothermal fields. Several parameters of organic geochemistry, used for assessing the maturity of bitumen, are well correlated with one another. In general, these parameters indicate that the Kairei sediments are more mature than the Logatchev sediments. The relationship between the inorganic parameters (REE/Fe and Eu/Eu ∗) and the organic parameter (bitumen maturity) might reflect changes of the hydrothermal influence on the sediments. The results of this study provide an insight into the variation of inorganic and organic geochemistry in deep-sea hydrothermal systems.

  19. Comparative assessment of five potential sites for hydrothermal magma systems: geochemistry

    SciTech Connect

    White, A.F.

    1980-08-01

    A brief discussion is given of the geochemical objectives and questions that must be addressed in such an evaluation. A summary of the currently published literature that is pertinent in answering these questions is presented for each of the five areas: The Geysers-Clear Lake region, Long Valley, Rio Grand Rift, Roosevelt Hot Springs, and the Salton Trough. The major geochemical processes associated with proposed hydrothermal sites are categorized into three groups for presentation: geochemistry of magma and associated volcanic rocks, geochemistry of hydrothermal solutions, and geochemistry of hydrothermal alteration. (MHR)

  20. 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

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2000-07-01

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Warrego Valles and Other Candidate Sites of Local Hydrothermal Activity Within The Thaumasia Region, Mars

    NASA Technical Reports Server (NTRS)

    Dohm, J. M.; Tanaka, K. L.; Lias, J. H.; Hare, T. M.; Anderson, R. C.; Gulick, V. C.

    1998-01-01

    We have previously demonstrated for the Thaumasia region of Mars that: (1) valley formation peaked during the Noachian and declined substantially during the Hesperian and Amazonian Periods and (2) valleys, many of which form networking systems, largely occur near volcanoes, highly faulted terrains, and large impact craters of similar age, thus suggesting hydrothermal activity. In Tanaka et al, the various hypotheses for valley formation on Mars are presented, and a geologic explanation for valley erosion in the Thaumasia region is given that "best fits" the region's geographic and geologic datasets. That comprehensive GIS-based investigation suggests that hydrothermal and seismic activity were the primary causes of valley formation in the Thaumasia region; the data make widespread precipitation less likely as a major factor in valley formation, except perhaps during the Early Noachian, for which much of the geologic record has been destroyed. Based on the reconstruction of the stratigraphic, tectonic, volcanic, and erosional histories and the close association of valleys in time and space with Noachian to Early Hesperian volcanoes and rift systems and Hesperian to Early Amazonian impact craters less than 50 km in diameter, we propose 13 sites of hydrothermal activity within the Thaumasia region; these are the best examples of valleys associated with these geologic features, but there are other less pronounced correlations elsewhere in the region.

  13. 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

  14. Hydrocarbons in surface sediments from a Guaymas Basin hydrothermal vent site. Technical report

    SciTech Connect

    Bazylinski, D.A.; Farrington, J.W.; Jannasch, H.W.

    1988-01-01

    Petroleum-like materials found at the Guaymas Basin hydrothermal vent site (Gulf of California) are derived from pyrolysis of organic matter. Two characteristics surface sediment cores differing in temperature profiles and other parameters were collected by DSV ALVIN, sectioned, and analyzed for hydrocarbons. The quantitative and qualitative composition of alkanes, steranes, diasteranes, and triterpanes differed between these cores as well as within sections of the same core. These differences, apparent for scales of tens of centimeters, are related to interactive physical, chemical, and microbial processes as well as the influence of multiple sources for the petroleum.

  15. 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.

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

    PubMed

    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

  17. 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

  18. Mantle to hydrothermal vent sites of the Southern Mariana Trough back-arc Basin: Results from the Taiga Project

    NASA Astrophysics Data System (ADS)

    Seama, N.; Okino, K.; Nogi, Y.; Sato, T.; Matsuno, T.; Yoshikawa, S.; Mochizuki, N.; Shinohara, M.

    2012-12-01

    The southern Mariana Trough back-arc basin shows an EPR type axial relief in morphology and constant low mantle Bouguer anomaly along the spreading axis (Kitada et al., 2006), suggesting abundance of magma supply, even though the full spreading rate of 40 km/Myr is categorized as slow spreading. Further, five hydrothermal vent sites exist within 5 km near the spreading axis at 13 N; two sites on the spreading axis, one site at the eastern foot of the axial high, and two sites on an off-axis knoll. We selected this area as one of three integrated target sites for the Taiga Project, and we conducted series of JAMSTEC research cruises for four different types of geophysical surveys, together with dive observation and samplings by the submersible Shinkai6500. The geophysical surveys consists of 1) a marine magnetotelluric (MT) survey of a 130 km length transect across the spreading axis using 10 ocean bottom electro-magnetometers, 2) a 15 km scale seismic reflection/refraction survey and seismicity observation using 9 ocean bottom seismometers (OBS), 3) near-bottom acoustic and magnetic mapping around all the hydrothermal sites using the AUV Urashima, and 4) a magnetometric resistivity (MMR) survey around the on-axis hydrothermal sites. Two-dimensional electrical resistivity structure of the upper mantle from the MT analysis shows highly asymmetry, which may be affected by hydration driven by water release from the subducting slab; that may result in abundant magma supply to support EPR type axial morphology. Three months OBS observation shows that the seismicity near the hydrothermal vent sites is very low, suggesting that hydrothermal activities are not related to tectonic stress. Moreover, the morphology of the mound and knoll near the three off-axis hydrothermal sites shows undeformed features without any faults, suggesting that their formation is closely related to an off-axis magma upwelling system rather than fault systems. The two on-axis hydrothermal sites

  19. Food Web Structure at South Su, Solwara 1 and Solwara 8 Hydrothermal Vent Sites (Manus Basin)

    NASA Astrophysics Data System (ADS)

    Honig, D. L.; Hsing, P.; Jones, R.; Schultz, T.; Sobel, A.; Thaler, A.; van Dover, C. L.

    2008-12-01

    A robust understanding of food webs in chemoautotrophically based hydrothermal vent ecosystems requires quantifying the input of local bacterial chemoautoptrophic production vs. photosynthetically derived debris from surface waters. As an initial step towards this goal for vent communities in Papua New Guinea's Manus Basin, we use isotopic ratios of carbon, nitrogen and sulfur to describe trophic relations among 17 invertebrate genera collected in July 2008 at the Solwara 1, Solwara 8 and South Su hydrothermal vent beds. Prior stable isotope work by Erickson, Macko and Van Dover (unpublished) at Manus Basin vent sites suggests that we will see relatively depleted ä13C and ä15N values for the primary consumers Ifremeria, Alviniconcha and Olgasolaris compared to secondary consumers like the mobile, scavenging genera Munidopsis, Austinograea, Alvinocaris and Chorocaris, sessile suspension feeders of the genera Eochinolasmus and Vulcanolepas, and the predatory sponge Abyssocladia. We further hypothesize that mobile fauna will exhibit greater within-genus variance of ä13C, ä15N and ä34S values than sessile genera due to mobile organisms' ability to forage for photosynthetically derived detritus.

  20. Deep-Sea Investigations on Hydrothermal Site Rainbow (MAR 36°14 N)

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Fouquet, Y.; Gente, P.; Ildefonse, B.; Thibaud, R.; Hoise, E.; Bissessur, D.; Yatheesh, V.; Scientific Party, M.

    2008-12-01

    Hydrothermal site Rainbow, one of the few known site on an ultramafic basement, is an exceptional target for the multidisciplinary study of hydrothermal phenomena. It is one of the two targets of the MoMAR (Monitoring the Mid Atlantic Ridge) project patronized by InterRidge, and is the focus of an IODP drilling project. What makes this site exceptional is the abundance of natural hydrogen, methane, and iron, an element which plays a major role in active processes, down to the scale of molecules. During Cruise MomarDream (25 Aug. - 15 Sept. 2008), R/V L'Atalante and ROV Victor spent 3 weeks on site Rainbow to carry out detailed investigation of this unique area. The goals of the cruise were, first, to study the role of iron in the geological, hydrological, and biological processes, and second, to identify potential drilling targets. Beyond the requirement of a "zero state" for the repeated observations and in fine the site monitoring in the framework of the MOMAR project, the completion of an exhaustive inventory of the biological populations is needed for the sake of preservation of a fragile environment. Multibeam bathymetry and magnetics have been collected by ROV Victor 50 m above the seafloor on a 4 km × 3 km wide box centered on the site and covering about 25% of the Rainbow Massif. Similarly, multibeam bathymetry, magnetics, and high resolution photographs have been acquired 10 m above the seafloor on a 650 m × 500 m box centered on the site, and on a 300 m × 300 m box centered on a field of dead clams. A nearly full coverage was obtained in these boxes. Direct geological exploration was also carried out and allowed the collection of rock samples, complemented by an intensive dredge program when the ROV was onboard. A large part of the cruise was devoted to biological studies sensu lato, including the collection of fluids dedicated to the study of abiotic organic molecules and metagenomics, the collection of sulfide for microbiological investigations, in

  1. 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

  2. Diversity of prokaryotic community at a shallow marine hydrothermal site elucidated by Illumina sequencing technology.

    PubMed

    Lentini, Valeria; Gugliandolo, Concetta; Bunk, Boyke; Overmann, Jörg; Maugeri, Teresa L

    2014-10-01

    To investigate the prokaryotic community structure and composition in an active hydrothermal site, named Black Point, off Panarea Island (Eolian Islands, Italy), we examined sediment and fluid samples, differing in temperature, by a massive parallel sequencing (Illumina) technique targeting the V3 region of the 16S rRNA gene. The used technique enabled us to detect a greater prokaryotic diversity than that until now observed and to reveal also microorganisms occurring at very low abundance (≤0.01 %). Most of sequences were assigned to Bacteria while Archaea were a minor component of the microbial community in both low- and high-temperature samples. Proteobacteria (mainly consisting of Alpha-, Gamma-, and Epsilonproteobacteria) dominated among all samples followed by Actinobacteria and Bacteroidetes. Analyzed DNA obtained from samples taken at different temperatures indicated the presence of members of different dominant genera. The main differences were observed between sediment samples where Rhodovulum and Thiohalospira prevailed at high temperature, while Thalassomonas and Sulfurimonas at low temperature. Chlorobium, Acinetobacter, Sulfurimonas, and Brevundimonas were abundant in both low- and high-temperature fluid samples. Euryarchaeota dominated the archaeal community in all samples. Classes of Euryarchaeota embracing hyperthermophilic members (Thermococci and Thermoplasmata) and of Crenarchaeota (Thermoprotei) were more abundant in high-temperature samples. A great number of sequences referred to Bacteria and Archaea still remained unaffiliated, indicating that Black Point site represents a rich source of so-far uncharted prokaryotic diversity. PMID:24849732

  3. Microbial utilization of naturally occurring hydrocarbons at the Guaymas Basin hydrothermal vent site

    SciTech Connect

    Bazylinski, D.A.; Wirsen, C.O.; Jannasch, H.W. )

    1989-11-01

    The Guaymas Basin (Gulf of California; depth, 2,000 m) is a site of hydrothermal activity in which petroliferous materials is formed by thermal alteration of deposited planktonic and terrestrial organic matter. We investigated certain components of these naturally occurring hydrocarbons as potential carbon sources for a specific microflora at these deep-sea vent sites. Respiratory conversion of (1-{sup 14}C)hexadecane and (1(4,5,8)-{sup 14}C)naphthalene to {sup 14}CO{sub 2} was observed at 4{degree}C and 25{degree}C, and some was observed at 55{degree}C, but none was observed at 80{degree}C. Bacterial isolates were capable of growing on both substrates as the sole carbon source. All isolates were aerobic and mesophilic with respect to growth on hydrocarbons but also grew at low temperatures (4 to 5{degree}C). These results correlate well with previous geochemical analyses, indicating microbial hydrocarbon degradation, and show that at least some of the thermally produced hydrocarbons at Guaymas Basin are significant carbon sources to vent microbiota.

  4. 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.

  5. Time-variation of hydrothermal discharge at selected sites in the western United States: implications for monitoring

    NASA Astrophysics Data System (ADS)

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

    2001-11-01

    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 anticipation 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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)

  10. Multidimensional Field Mapping of Gaseous C-H-O-S Species in Hydrothermal Systems: Distinguishing Potential Sites for Hydrocarbon Generation

    NASA Astrophysics Data System (ADS)

    Schwandner, F. M.; Dunn, E. E.; Shock, E. L.

    2005-12-01

    Organic compounds in hydrothermal gas emissions have been documented since the mid-1800's, yet their origin is still a matter of some debate. Thermal alteration such as maturation and cracking can produce thermogenic hydrocarbons from pre-existing organic matter in hydrothermal systems. Gas-phase radical reactions and catalytic hydrogenation reactions of CO2 and CO to methane and higher hydrocarbons have also been suggested as being responsible for observations of organic compounds in hydrothermal emissions. Recently published data indicated that some organic signatures in volcanic-hydrothermal systems cannot be explained by pre-existing organic matter alone, and more representative analyses are now required to shed light on this question. Choosing a representative site within a hydrothermal field for sampling is in itself a complicated task, and heterogeneities can be easily missed. Spatial analysis of the distribution of C-O-H-S species in the gas phase can potentially indicate possible sites of increased hydrocarbon generation potentials via the catalytic hydrogenation pathway. This approach offers the advantage of providing information in the field that can be used to judge appropriate sampling locations prior to the more complex and costly standard organic analyses of gaseous emissions. A portable multi-sensor system with electrochemical and infrared sensors can in a short time provide large spatial data sets that yield potential target areas for selectively sampling organic compounds. Statistical methods, including probability tests and spatial correlation of concentrations and fluxes of selected species, can be applied later to yield information on the number of populations as well as genetic relationships between different populations. This approach was tested at three acid-sulfate sites in Yellowstone National Park, USA. The chosen sites were the Greater Obsidian Pool area (GOPA, Mud Volcanoes hot spring group), the Sylvan Springs area, and the Washburn

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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. PMID:24893665

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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

  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. The NeMO Explorer Web Site: Interactive Exploration of a Recent Submarine Eruption and Hydrothermal Vents, Axial Volcano, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Weiland, C.; Chadwick, W. W.; Embley, R. W.

    2001-12-01

    To help visualize the submarine volcanic landscape at NOAA's New Millennium Observatory (NeMO), we have created the NeMO Explorer web site: http://www.pmel.noaa.gov/vents/nemo/explorer.html. This web site takes visitors a mile down beneath the ocean surface to explore Axial Seamount, an active submarine volcano 300 miles off the Oregon coast. We use virtual reality to put visitors in a photorealistic 3-D model of the seafloor that lets them view hydrothermal vents and fresh lava flows as if they were really on the seafloor. At each of six virtual sites there is an animated tour and a 360o panorama in which users can view the volcanic landscape and see biological communities within a spatially accurate context. From the six sites there are hyperlinks to 50 video clips taken by a remotely operated vehicle. Each virtual site concentrates on a different topic, including the dynamics of the 1998 eruption at Axial volcano (Rumbleometer), high-temperature hydrothermal vents (CASM and ASHES), diffuse hydrothermal venting (Marker33), subsurface microbial blooms (The Pit), and the boundary between old and new lavas (Castle vent). In addition to exploring the region geographically, visitors can also explore the web site via geological concepts. The concepts gallery lets you quickly find information about mid-ocean ridges, hydrothermal vents, vent fauna, lava morphology, and more. Of particular interest is an animation of the January 1998 eruption, which shows the rapid inflation (by over 3 m) and draining of the sheet flow. For more info see Fox et al., Nature, v.412, p.727, 2001. This project was funded by NOAA's High Performance Computing and Communication (HPCC) and Vents Programs. Our goal is to present a representative portion of the vast collection of NOAA's multimedia imagery to the public in a way that is easy to use and understand. These data are particularly challenging to present because of their high data rates and low contextual information. The 3-D models create

  14. 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

  15. Discovery and drilling of on- and off-axis hydrothermal sites in backarc spreading center of southern Mariana Trough, Western Pacific

    NASA Astrophysics Data System (ADS)

    Urabe, T.; Ishibashi, J.; Maruyama, A.; Marumo, K.; Seama, N.; Utsumi, M.

    2004-12-01

    The Mariana Trough is an actively spreading backarc basin that is located along the eastern margin of Philippine Sea Plate. GPS monitoring indicates that the rate of spreading is about 45 mm/yr in the southern section (Kato et al., 2003). No transform fault offsets exist despite significant changes in the trend of the spreading center. Fryer et al. (1998) pointed out the close proximity of submarine arc volcanoes to the spreading center and tectonic fabric that is at a high angle to the trend of the spreading center on the eastern flank. Three hydrothermal sites were discovered along such tectonic lineament in southern Mariana Trough (12o55-57'N, 143o37-39'E). On-axis site (so-called Fryer site, depth: 2,850 m) consists of a hydrothermal mound about 20 m in diameter that develops on pillow lava of a segment center of the spreading axis. The segment is characterized by highly variable rock composition (up to 68% SiO2). Repeated temperature measurements revealed rapid cooling of the hydrothermal system from 240oC in April 2003, through 112oC in October 2003 to 69oC in March 2004. On the other hand, two off-axis sites seem to have longevity of life: The Archaean site which locates about 2 km off-axis on the eastern (arc side) skirt is characterized by its huge sulfide spire; 50 m in height and 20 m in diameter. It is composed of pyrite, chalcopyrite and sphalerite, and is emanating hydrothermal fluids up to 220oC. In the third site (Pika site), active black smokers (max. temp. = 330oC), numerous dead chimneys and sulfide mounds were found on a basaltic seamount about 5 km off-axis. These lines of evidence support the idea of Fryer et al. (1998) that the backarc magma is replenished by arc/off-axis magma along the tectonic lineation. The first and third sites been drilled and cased using a tethered, submarine rock-drill system BMS (Benthic Multi-coring System) on-board the R/V Hakurei-Maru # 2 as a part of Archaean Park Project*. Rocks from two holes (7.5 m and 4.1 m

  16. 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

  17. 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

  18. Analysis of microbial community structures within the core recovered at hydrothermal site of Suiyo seamount, Izu-Bonin Arc, Western Pacific

    NASA Astrophysics Data System (ADS)

    Nakagawa, T.; Maruyama, A.; Urabe, T.; Fukui, M.

    2002-12-01

    Microbial communities in a core obtained from hydrothermal site of Suiyo seamount, Izu-Bonin Arc, Western Pacific (140 38'E, 28 34'N; -1391 m), were characterized using PCR-denaturing gradient gel electrophoresis (DGGE) analysis based on the 16S rRNA gene. The core (APSK05) was collected with the tethered marine rock-drill so called 'BMS' to approach the Subvent Biosphere directly below the seafloor. The depth of the bore hole was 6.6 m, and the length of recovered core was 3.6 m. The hydrothermal fluid with temperature 304?C came out of the hole at the 4.4 m depth of the hole. This phenomenon suggests that the hydrothermal fluid came out in the result of the perforation of cap rock sealed by clay. The subcore APSK05-2-1 (pumicite) from the surface of the bore hole, APSK05-2-2 (clay with fine sulfide crystals) from the ca. 1 m depth of the bore hole, APSK05-3-2 (clay stone) from the ca. 3 m depth of the bore hole, and APSK05-5-2 (dacite with very fine pyrite) from the ca. 5 m depth of the bore hole were fractured with the vise, respectively. The eubacterial 16S rRNA gene fragments were obtained in the core from 0 to 3.4 m of core length by PCR amplification using the specific primer set. The PCR-DGGE analysis showed the bacterial bands affiliated with alpha, beta, gamma-Proteobacteria, and Firmicutes. A part of the bacterial bands was related to the microbe clones retrieved from the terrestrial hot springs. This result suggests that the core above the cap rock kept the temperature suited for moderate thermophilic microbes.

  19. 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.

  20. Proteomic tracking of hydrothermal Maillard and redox modification in lactoferrin and β-lactoglobulin: Location of lactosylation, carboxymethylation, and oxidation sites.

    PubMed

    Dyer, Jolon M; Clerens, Stefan; Grosvenor, Anita; Thomas, Ancy; Callaghan, Chris; Deb-Choudhury, Santanu; Haines, Stephen

    2016-05-01

    Lactoferrin and β-lactoglobulin are important protein components of mammalian milk. Maillard reactions, as well as redox chemistry, are of particular interest for dairy products because they are known to occur during common processing steps, notably heating procedures such as pasteurization. Using a redox proteomics approach, we characterized AA residue side-chain modification across a range of heating times and with or without the specific addition of lactose, to both map the key modification sites within these proteins and evaluate their sensitivity to process-induced modification. Heating in the presence of lactose resulted in significant Maillard modification (both lactosylation and carboxymethylation) to both bovine lactoferrin and β-lactoglobulin. Notably, Lys47, a key residue in the bioactive peptide lactoferricin, was particularly susceptible to modification. Lactoferrin appeared to be fairly robust to hydrothermal treatment, with relatively low levels of oxidative modification observed. In contrast, β-lactoglobulin was susceptible to significant oxidative modification under hydrothermal treatment, with the range and type of modifications observed suggesting compromised nutritional value. These results have important implications for processing applications in dairy foods where retention of biological function and optimal protein quality is desired. PMID:26923048

  1. 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

  2. Hydrothermal alteration products of gabbros help accommodate exhumation-related deformation in mantle-derived ultramafics exposed at the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Picazo, S.; Cannat, M.; Escartin, J.; Gibert, B.; Delacour, A.; Silantyev, S.

    2011-12-01

    Outcrops of deeply-derived ultramafic rocks and gabbros are widespread along slow spreading ridges but the rheology and dynamics of the exhumation faults and of their uplifted footwalls are still poorly known. Previous studies of samples collected within meters of exposed exhumation fault surfaces in the Atlantic have shown that a gabbroic component was added to the primarily ultramafic material in the fault zone, allowing for the growth of abundant amphibole, chlorite and talc. The nature of this component (altered magmatic intrusions or metasomatic hydrothermal fluids) could not, however, be ascertained in the pervasively sheared fault material. In this abstract we report on a set of 474 samples collected at the Mid-Atlantic Ridge (MAR) during the Serpentine cruise (2007; RV Pourquoi Pas? PI Y. Fouquet) next to the ultramafic-hosted Ashadze (13°N) and Logatchev (14°45'N) vent fields. Most of these 474 samples are weakly to moderately deformed and are interpreted as representing the upper few hundred meters below their respective exhumation fault zone, rather than the fault zone itself. The large number of samples, and their overall moderate degree of deformation gives us a chance to propose a semi-statistical study of plastic, brittle-plastic and brittle deformation in ultramafic rocks next to a MAR exhumation system, in relation with the magmatic and hydrothermal history. Our primary finding is that significant brittle-plastic deformation systematically involves amphibole±chlorite±talc-bearing ultramafic lithologies. Serpentine is commonly present in these deformed assemblages, but we did not find serpentine-only shear zones. Amphibole (in successive generations ranging from hornblende to tremolite) and chlorite occur in veins, many of which also contain zircon and some relict plagioclase, indicating a magmatic origin. Relicts of primary peridotite minerals in the most amphibole-rich samples indicate that magmatic injection followed on an episode of

  3. 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

  4. 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

  5. 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

  6. Hydrothermal Processes

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly back to the seafloor where they are expelled into the overlying water column. Seafloor hydrothermal circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine hydrothermal venting and their accompanying chemosynthetically based communities in the late 1970s remains one of the most exciting discoveries in modern science. The existence of some form of hydrothermal circulation had been predicted almost as soon as the significance of ridges themselves was first recognized, with the emergence of plate tectonic theory. Magma wells up from the Earth's interior along "spreading centers" or "MORs" to produce fresh ocean crust at a rate of ˜20 km3 yr-1, forming new seafloor at a rate of ˜3.3 km2 yr-1 (Parsons, 1981; White et al., 1992). The young oceanic lithosphere formed in this way cools as it moves away from the ridge crest. Although much of this cooling occurs by upward conduction of heat through the lithosphere, early heat-flow studies quickly established that a significant proportion of the total heat flux must also occur via some additional convective process (Figure 1), i.e., through circulation of cold seawater within the upper ocean crust (Anderson and Silbeck, 1981). (2K)Figure 1. Oceanic heat flow versus age of ocean crust. Data from the Pacific, Atlantic, and Indian oceans, averaged over 2 Ma intervals (circles) depart from the theoretical cooling curve (solid line) indicating convective cooling of young ocean crust by circulating seawater

  7. 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.

  8. 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.

  9. 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

  10. Hydrothermal processes in partially serpentinized peridotites from Costa Rica: evidence from native copper and complex sulfide assemblages

    NASA Astrophysics Data System (ADS)

    Schwarzenbach, Esther M.; Gazel, Esteban; Caddick, Mark J.

    2014-11-01

    Native metals and metal alloys are common in serpentinized ultramafic rocks, generally representing the redox and sulfur conditions during serpentinization. Variably serpentinized peridotites from the Santa Elena Ophiolite in Costa Rica contain an unusual assemblage of Cu-bearing sulfides and native copper. The opaque mineral assemblage consists of pentlandite, magnetite, awaruite, pyrrhotite, heazlewoodite, violarite, smythite and copper-bearing sulfides (Cu-pentlandite, sugakiite [Cu(Fe,Ni)8S8], samaniite [Cu2(Fe,Ni)7S8], chalcopyrite, chalcocite, bornite and cubanite), native copper and copper-iron-nickel alloys. Using detailed mineralogical examination, electron microprobe analyses, bulk rock major and trace element geochemistry, and thermodynamic calculations, we discuss two models to explain the formation of the Cu-bearing mineral assemblages: (1) they formed through desulfurization of primary sulfides due to highly reducing and sulfur-depleted conditions during serpentinization or (2) they formed through interaction with a Cu-bearing, higher temperature fluid (350-400 °C) postdating serpentinization, similar to processes in active high-temperature peridotite-hosted hydrothermal systems such as Rainbow and Logatchev. As mass balance calculations cannot entirely explain the extent of the native copper by desulfurization of primary sulfides, we propose that the native copper and Cu sulfides formed by local addition of a hydrothermal fluid that likely interacted with adjacent mafic sequences. We suggest that the peridotites today exposed on Santa Elena preserve the lower section of an ancient hydrothermal system, where conditions were highly reducing and water-rock ratios very low. Thus, the preserved mineral textures and assemblages give a unique insight into hydrothermal processes occurring at depth in peridotite-hosted hydrothermal systems.

  11. 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.

  12. Use of Various Rock Physics Models Combined with a Rock Physics Database to Better Characterize Velocity Dispersion Effects in Potential Enhanced Oil Recovery, Carbon Sequestration and Hydrothermal Sites

    NASA Astrophysics Data System (ADS)

    Purcell, C. C.; Mur, A. J.; Delany, D.; Haljasmaa, I. V.; Soong, Y.; Harbert, W.

    2011-12-01

    The exploration of velocity differences in various fluid saturated rock types under reservoir conditions should prove to be useful in seismic monitoring of sequestration and hydrothermal sites. Different saturation values, along with mixtures of other common pore fluids could help delineate various areas of a CO2 flood or enhanced geothermal pressurization, in addition to estimating a minimum saturation amount needed to be seen in seismic surveys. We also explore the effects of varying parameters on the saturated velocities, including porosity, bulk frame composition, pressure, temperature, different pore filling phases, fluid mixtures, and compliant porosity. A software toolkit is currently in development that would allow exploration of these parameters to be easily achieved and visualized. Fluid substitution using Gassmann's equation (Gassmann [1]) is an important tool in the analysis of velocity dispersion in saturated rocks. Mavko and Jizba [2] created a model of squirt dispersion for elastic wave velocities at ultrasonic frequencies that predicts total dispersion for fluid filled rocks. Gurevich et al. [3] extend the Mavko-Jizba expressions to low fluid bulk modulus situations, such as gas filled rocks. These equations are typically used to calculate velocities of rocks filled with typical pore filling phases such as brine or gas. Purcell et al. [4] compared these equations to CO2 saturated limestone samples at reservoir pressures and temperatures. This paper compares the accuracy of these equations over various pressures and temperature ranges for a variety of rock types. Dry rock ultrasonic lab measurements of velocity have been made for carbonate, sandstone, rhyolite and coal and incorporated into a rock physics database. In addition, waveforms for each measurement have been used to estimate Q. Measurements were made between 2.3 and 50 MPa with generally a minimum of 40 measurements per sample completed. Various saturating phases, including supercritical CO

  13. 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/cgi-bin/nph-data_query?bibcode=2012AGUFMOS51D1896R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS51D1896R&link_type=ABSTRACT"><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('http://adsabs.harvard.edu/abs/2015EGUGA..1711977A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711977A"><span id="translatedtitle">Control of fault geometry and permeability contrast on fault-related <span class="hlt">hydrothermal</span> fluid flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andersen, Christine; Rüpke, Lars; Hasenclever, Jörg; Grevemeyer, Ingo; Petersen, Sven</p> <p>2015-04-01</p> <p>High-temperature black smoker systems along slow-spreading ridges such as the Mid-Atlantic Ridge (MAR) are frequently related to tectonic fault zones and therefore are commonly found off axis. While preferential flow of hot fluids along highly permeable, fractured rocks seems intuitive, such efficient flow leads to the entrainment of cold ambient seawater resulting in a drastic decrease in vent temperatures. This temperature drop is difficult to reconcile with high-temperature black smoker activity observed at outcropping fault zones. In our recent study we aim to resolve this apparent contradiction by combining newly acquired seismological data (Grevemeyer et al., 2013) from the high-temperature, off-axis <span class="hlt">Logatchev</span> 1 <span class="hlt">hydrothermal</span> field (LHF1) along the MAR with 2D <span class="hlt">hydrothermal</span> flow modeling. The seismic data shows intense off-axis seismicity with focal mechanisms suggesting a fault zone dipping from LHF1 toward the ridge axis. In order to explain fault-related high-temperature <span class="hlt">hydrothermal</span> discharge as observed at LHF1, our simulations predict that fault zones need to be just permeable and wide enough to capture and redirect <span class="hlt">hydrothermal</span> plumes rising from depth but, because they are not isolated conduits, must not be too wide or permeable in order to prevent cooling through mixing with ambient colder fluids. The two controlling parameters fault width and permeability contrast between fault and surrounding rock can be expressed as a single term, the relative transmissibility of the fault zone, which is defined by the product of the two. Low relative fault transmissibility leads to plumes that cross the fault and vent above the heat source rather than at the fault termination at the seafloor. High relative fault transmissibility leads to significantly lower vent exit temperatures than those observed at black smoker systems. Our findings further illustrate the intrinsic relationship between permeability, mass flux and upflow temperature: the higher the permeability</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="http://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=20010020499&hterms=characteristics+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcharacteristics%2Blife','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010020499&hterms=characteristics+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcharacteristics%2Blife"><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://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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeCoA.159...16W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeCoA.159...16W&link_type=ABSTRACT"><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://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> </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://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/2004AGUFM.V41B1379M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V41B1379M"><span id="translatedtitle">Molecular ecological analysis of the distribution and diversity of sulfate-reducing prokaryotes and microbes in deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> of the Suiyo Seamount, Izu-Bonin Arc, and the Mariana Arc-Backarc, Western Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maruyama, A.; Nakagawa, T.; Hase, Y.; Ishibashi, J.; Yamanaka, T.; Morimoto, Y.; Kimura, H.; Urabe, T.; Fukui, M.</p> <p>2004-12-01</p> <p>The present study describes the distribution and diversity of sulfate-reducing prokaryotes from the deep-sea <span class="hlt">hydrothermal</span> vent field at the Suiyo Seamount, Izu-Bonin Arc, and the Mariana Arc-Backarc Western Pacific. We used a PCR-based metabolic molecular ecology approach that targets a conserved region of subunit A and B of the dissimilatory sulfite reductase (DSR) gene and subunit A of the adenosine-5'-phosphosulfate (APS) reductase gene. The DSR genes were obtained from microbes that grew in catheter-type in situ growth chamber deployed for three days on a vent, and from the effluent water of drilled holes at 5 degree C and natural vent fluids at 7 degree C in the Suiyo. The DSR clones were not closely related to cultivated species or environmental clones. Similarly, novel APS clones were obtained from the mat developed at <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in the Mariana. Moreover, samples of microbial communities from the Suiyo were examined using PCR-denaturing gradient gel electrophoresis (DGGE) analysis based on the 16S rRNA gene. The sequence analysis of 16S rRNA gene fragments obtained from the vent-catheter after a three-day incubation revealed the occurrence of bacterial DGGE bands affiliated with the Aquificae, gamma-, and epsilon-Proteobacteria as well as the occurrence of archaeal phylotypes affiliated with the Thermococcales and of a unique Archaeon sequence clustered with Nanoarchaeota. The DGGE bands obtained from drilled holes and natural vent fluids from 7 to 300 degree C were affiliated with the delta-Proteobacteria, genus Thiomicrospira and Pelodictyon. The dominant DGGE bands retrieved from the effluent water of casing pipes at 3 and 4 degree C were closely related to phylotypes obtained from the Arctic Ocean. Our results suggest the presence of microorganisms corresponding to a unique DSR and APS lineage not detected previously from other geothermal environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13B1728P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13B1728P"><span id="translatedtitle">Comparing the deformation and <span class="hlt">hydrothermal</span> alteration record of tectonic exhumation of mantle-derived ultramafic rocks from the Mid-Atlantic Ridge and from Ocean Continent Transitions (Central Alps and Western Iberia Margin)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Picazo, S. M.; Cannat, M.; Manatschal, G.</p> <p>2012-12-01</p> <p>The exhumation of mantle-derived rocks is widespread at slow and ultraslow Mid-Ocean Ridges and at the Ocean-Continent Transition (OCT) of rifted continental margins. It occurs along large offset normal faults also called detachment faults. Thermo-mechanical models indicate that significant strain softening of the fault rocks in the footwall is required in order to produce such large fault offsets. Our work focuses on actual deformation textures, and the associated mineralogy in ultramafic rocks sampled in the upper levels of the footwall next to the exhumation fault at two contrasted exhumation settings: the Mid-Atlantic Ridge (MAR) at lat. 13°N and 15°N (next to the Ashadze and <span class="hlt">Logatchev</span> vent <span class="hlt">sites</span>); and two OCT examples, the Totalp relict of a paleo-Tethys OCT exposed in SE Switzerland, and the Iberian distal margin (ODP Leg 173 <span class="hlt">Site</span> 1070). These two settings differ by a number of characteristics, most notably the nature of the exhumed mantle (sub-continental mantle at OCTs, oceanic mantle at the ridge) and the extent of magmatic activity during exhumation (extensive magmatism at the MAR, few magmatic rocks at OCTs). Our comparative approach aims at identifying possible differences in the deformation processes during exhumation. We show that in both settings the ultramafic rocks in the upper levels of the footwall next to the detachment fault undergo a series of plastic to semi-brittle and brittle deformations. In samples from OCT settings, we find a cataclasites to gouges-sequence that affects the serpentinized peridotites. It involves a component of plastic deformation of serpentine following pronounced brittle grain-size reduction responsible for matrix-supported gouges formation in the most highly strained intervals. In this case the rheology of serpentine therefore controls the detachment fault. A similar sequence of serpentinite cataclasites and gouges is found in a few samples at one of the studied MAR locations, but in most samples from the MAR we find</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PEPS....1....5N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PEPS....1....5N"><span id="translatedtitle">Theoretical constraints of physical and chemical properties of <span class="hlt">hydrothermal</span> fluids on variations in chemolithotrophic microbial communities 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>Nakamura, Kentaro; Takai, Ken</p> <p>2014-12-01</p> <p>In the past few decades, chemosynthetic ecosystems at deep-sea <span class="hlt">hydrothermal</span> vents have received attention as plausible analogues to the early ecosystems of Earth, as well as to extraterrestrial ecosystems. These ecosystems are sustained by chemical energy obtained from inorganic redox substances (e.g., H2S, CO2, H2, CH4, and O2) in <span class="hlt">hydrothermal</span> fluids and ambient seawater. The chemical and isotope compositions of the <span class="hlt">hydrothermal</span> fluid are, in turn, controlled by subseafloor physical and chemical processes, including fluid-rock interactions, phase separation and partitioning of fluids, and precipitation of minerals. We hypothesized that specific physicochemical principles describe the linkages among the living ecosystems, <span class="hlt">hydrothermal</span> fluids, and geological background in deep-sea <span class="hlt">hydrothermal</span> systems. We estimated the metabolic energy potentially available for productivity by chemolithotrophic microorganisms at various <span class="hlt">hydrothermal</span> vent fields. We used a geochemical model based on <span class="hlt">hydrothermal</span> fluid chemistry data compiled from 89 globally distributed <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span>. The model estimates were compared to the observed variability in extant microbial communities in seafloor <span class="hlt">hydrothermal</span> environments. Our calculations clearly show that representative chemolithotrophic metabolisms (e.g., thiotrophic, hydrogenotrophic, and methanotrophic) respond differently to geological and geochemical variations in the <span class="hlt">hydrothermal</span> systems. Nearly all of the deep-sea <span class="hlt">hydrothermal</span> systems provide abundant energy for organisms with aerobic thiotrophic metabolisms; observed variations in the H2S concentrations among the <span class="hlt">hydrothermal</span> fluids had little effect on the energetics of thiotrophic metabolism. Thus, these organisms form the base of the chemosynthetic microbial community in global deep-sea <span class="hlt">hydrothermal</span> environments. In contrast, variations in H2 concentrations in <span class="hlt">hydrothermal</span> fluids significantly impact organisms with aerobic and anaerobic hydrogenotrophic metabolisms</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1167674','SCIGOV-STC'); 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/scitech">SciTech Connect</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/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://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=34533&keyword=hydrothermal&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=62234007&CFTOKEN=60056246','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=34533&keyword=hydrothermal&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=62234007&CFTOKEN=60056246"><span id="translatedtitle">COMBUSTION OF <span class="hlt">HYDROTHERMALLY</span> TREATED COALS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The report gives results of an evaluation of: (1) the relationship of the combustion characteristics of <span class="hlt">hydrothermally</span> treated (HTT) coals to environmental emissions, boiler design, and interchangeability of solid fuels produced by the <span class="hlt">Hydrothermal</span> Coal Process (HCP) with raw coa...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6501742','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6501742"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> pretreatment of coal</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Loo, Bock; Ross, D.S.</p> <p>1990-08-14</p> <p>We are examining the effects on composition and behavior of Argonne-supplied Wyodak coal under both thermal (no added water/N{sub 2}) and <span class="hlt">hydrothermal</span> (liquid water/N{sub 2}) conditions at 350{degree}C for periods of 30 min and 5 hr, with emphasis during this period on the longer treatment. Field ionization mass spectrometry (FIMS) of the untreated, thermally treated, and <span class="hlt">hydrothermally</span> treated coals is conducted at conditions where the samples are heated from ambient to 500{degree}C at 2.5{degree}/min. In the 5 hr work the volatilities of the coals are 24%, 16%, and 25% respectively. Solvent swelling studies with the recovered coals do not demonstrate the expected lower degree of crosslinking in the <span class="hlt">hydrothermal</span> case. Both the thermal and <span class="hlt">hydrothermal</span> treatments yield products with a decreased swelling ratio, but the ratio for the product from the aqueous treatment is slightly lower than that from thermal treatment. At present we cannot reconcile this result with our other data. 4 refs., 6 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V13B2850J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V13B2850J"><span id="translatedtitle">The <span class="hlt">Hydrothermal</span> System at the Grand Canyon of the Yellowstone River: Exposed and Hidden</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jaworowski, C.; Heasler, H. P.; Susong, D. D.; Neale, C. M.; Sivarajan, S.; Masih, A.</p> <p>2012-12-01</p> <p>Combining calibrated and corrected night-time, airborne thermal infrared imaging with field information from the 2008 drilling of the Canyon borehole strainmeter (B206) in Yellowstone National Park emphasizes the extensive nature of Yellowstone's <span class="hlt">hydrothermal</span> system. Both studies contributed to an understanding of the vertical and horizontal flow of heat and fluids through the bedrock in this area. Night-time, airborne thermal infrared imagery, corrected for emissivity and atmosphere clearly shows north-trending faults and fractures transmitting heat and fluids through the rhyolitic bedrock and into the overlying glacial sediments near the Canyon borehole. Along the Grand Canyon of the Yellowstone, the Clear Lake <span class="hlt">hydrothermal</span> area is an example of <span class="hlt">hydrothermal</span> alteration at the ground surface. The numerous <span class="hlt">hydrothermal</span> features exposed in the nearby Grand Canyon of the Yellowstone River and its <span class="hlt">hydrothermally</span> altered walls are clear evidence of the exposed <span class="hlt">hydrothermal</span> system. The bedrock geology, geologic processes, and <span class="hlt">hydrothermal</span> activity combined to form the dramatic Grand Canyon of the Yellowstone. The night-time thermal infrared imagery provides a new view of this exposed <span class="hlt">hydrothermal</span> system for scientists and visitors. Scientists and Yellowstone Park managers carefully <span class="hlt">sited</span> the Canyon borehole strainmeter in a green, grassy meadow to insure successful completion of the borehole in a non-<span class="hlt">hydrothermal</span> area. The closest <span class="hlt">hydrothermal</span> feature to the drilling <span class="hlt">site</span> was about 2.5 km to the east. Although excellent exposures of <span class="hlt">hydrothermal</span> altered bedrock are present about 1.5 km east at the Lower Falls and the Grand Canyon of the Yellowstone River, the connection between exposed <span class="hlt">hydrothermal</span> areas and the borehole <span class="hlt">site</span> was not obvious. After drilling through 9 m of brown-gray muds and 113 m of rock, a bottom hole temperature of 81.2 degrees Celsius precluded drilling the hole any deeper than 122 m. The post-drilling data collected from B206 and the airborne</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/2015EGUGA..1713267R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1713267R"><span id="translatedtitle">Energetics of <span class="hlt">hydrothermal</span> convection in heterogeneous ocean crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruepke, Lars; Hasenclever, Joerg; Andersen, Christine</p> <p>2015-04-01</p> <p>Recent advances in <span class="hlt">hydrothermal</span> flow modeling have revealed the key thermodynamic and fluid-dynamic controls on <span class="hlt">hydrothermal</span> convection and vent temperatures at oceanic spreading centers. The observed upper limit to black smoker vent temperatures of approx. 400°C can be explained by the thermodynamic properties of water (Jupp and Schultz, 2000). Likewise, 3D models of <span class="hlt">hydrothermal</span> flow at fast-spreading ridges show cylindrical upwellings with closely interwoven recharge flow (Coumou et al., 2008, Hasenclever et al., 2014). While these studies provide a robust theoretical basis for <span class="hlt">hydrothermal</span> flow observations at fast-spreading ridges, the situation at slow-spreading ridges is different. The slow-spreading Mid-Atlantic Ridge produces highly heterogeneous crust along its tectonic and magmatic segments with significant permeability contrasts across structural and lithological interfaces. The sub-seafloor permeability structure has a strong control on vent field location such that off-axis <span class="hlt">hydrothermal</span> systems are apparently consistently located at outcropping fault zones. We have recently shown that preferential flow along high-permeability conduits inevitably leads to the entrainment of cold ambient seawater (Andersen et al., 2014), which causes a temperature drop that is difficult to reconcile with fault-related high-temperature venting. A fundamental question is therefore how <span class="hlt">hydrothermal</span> fluids can maintain their high temperature while flowing kilometers from a driving heat source through highly heterogeneous crust to a vent <span class="hlt">site</span> at the seafloor? We address this question by exploring the energetics of <span class="hlt">hydrothermal</span> convection in heterogeneous ocean crust using 2D and 3D flow simulations. In our analysis we focus on the energy balance of rising <span class="hlt">hydrothermal</span> plumes and on mixing processes at permeability boundaries, with the aim to establish a more robust theoretical framework for <span class="hlt">hydrothermal</span> flow through highly heterogeneous seafloor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22A..07S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22A..07S&link_type=ABSTRACT"><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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AGUFM.P31G..02R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AGUFM.P31G..02R&link_type=ABSTRACT"><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://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://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> </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/2015AGUFM.V13C3152C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3152C"><span id="translatedtitle">Baseline <span class="hlt">Hydrothermal</span> Monitoring Data from Cascade Range Volcanoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crankshaw, I. M.; Ingebritsen, S.; Randolph-Flagg, N. G.; Newman, A. C.; Evans, W.; Spicer, K. R.; Ledingham, G.</p> <p>2015-12-01</p> <p>Since 2009 the U.S. Geological Survey has systematically monitored <span class="hlt">hydrothermal</span> behavior at selected Cascade Range volcanoes in order to define baseline <span class="hlt">hydrothermal</span> and geochemical conditions. Gas and water data have been collected at 25 monitoring <span class="hlt">sites</span> on 10 of the highest-risk volcanoes in the Cascade Range. These <span class="hlt">sites</span> include 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. The monitoring data are intended to (1) be suitable for comparison with other continuous geophysical monitoring data and (2) provide baseline data that will be useful during future episodes of volcanic unrest. <span class="hlt">Site</span> records consist mainly of hourly temperature and (or) <span class="hlt">hydrothermal</span> solute flux data spanning multiple years. Many of the <span class="hlt">hydrothermal</span> time series data show considerable variability during quiescent periods, including diurnal, seasonal, and inter-annual variability. Having established baseline conditions, we are reducing our monitoring frequency, and data are being archived and analyzed with a view to providing useful and succinct summaries of baseline behavior during quiescent periods. The <span class="hlt">hydrothermal</span> response to recent (November 2014 to present) unrest at Lassen Volcanic Center demonstrates the utility of long-term background data, which has made it straightforward to isolate symptoms of unrest.</p> </li> <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('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, III; 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('http://adsabs.harvard.edu/abs/2011AGUFMOS11C..05B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMOS11C..05B"><span id="translatedtitle">Temporal monitoring and quantification of <span class="hlt">hydrothermal</span> activity from photomosaics and 3D video reconstruction: The Lucky Strike <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>Barreyre, T.; Escartin, J.; Cannat, M.; Garcia, R. A.</p> <p>2011-12-01</p> <p>Seafloor imagery provides detailed and accurate constrain on the distribution, geometry, and nature of <span class="hlt">hydrothermal</span> outflow, and its links to the ecosystems that they sustain. Repeated surveys allow us to evaluate the temporal variability of these systems. Geo-referenced and co-registered photomosaics of the Lucky Strike <span class="hlt">hydrothermal</span> field (Mid Atlantic Ridge, 37°N), derived from >60,000 seafloor images acquired in 1996, 2006, 2008 and 2009, using deep-towed and ROV vehicles. Newly-developed image processing techniques, specifically tailored to generate giga-mosaics in the underwater environment, include correction of illumination artifacts and removal of the edges between individual images so as to obtain a continuous and single mosaic image over a surface of up ~800x800 m and with a pixel resolution of 5-10 mm. Photomosaicing is complemented by 3D-reconstruction of <span class="hlt">hydrothermal</span> edifices from video imagery, with the mapping of image texture over the 3D model surface. These image and video data can also be directly linked with high-resolution microbathymetry acquired near-bottom acoustic systems. Preliminary analysis of these mosaics reveals the distribution of low-temperature <span class="hlt">hydrothermal</span> outflow, recognizable owing to its association with bacterial mats and <span class="hlt">hydrothermal</span> deposits easily identifiable in the imagery. These low-temperature venting areas, often associated with high-temperature <span class="hlt">hydrothermal</span> vents, are irregularly distributed throughout the <span class="hlt">site</span>, defining clusters. In detail, the outflow geometry is largely controlled by the nature of the substrate (e.g., cracks and fissures, diffuse flow patches, existing <span class="hlt">hydrothermal</span> constructs). The spatial relationships between the high- and diffuse venting as revealed by the imagery provide constraints on the shallow plumbing structure throughout the <span class="hlt">site</span>.. Imagery provides constraints on temporal variability at two time-scales. First, we can identify changes in the distribution and presence of actively venting</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://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., III; 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/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/cgi-bin/nph-data_query?bibcode=2016GGG....17..375D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GGG....17..375D&link_type=ABSTRACT"><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/2013AGUFM.B13B0470Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B13B0470Y"><span id="translatedtitle">Probing <span class="hlt">Hydrothermal</span> Organic Reaction Mechanisms with <span class="hlt">Hydrothermal</span> Photochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Z.; Gould, I.; Shock, E.</p> <p>2013-12-01</p> <p>In most <span class="hlt">hydrothermal</span> organic experiments the emphasis is on reaction product distributions and kinetic measurements, with mechanistic information or the direct evidence of proposed reaction intermediates rare or lacking. We believe that greater mechanistic insight will yield greater predictive power. Previously, we studied the reactions of a model ketone, dibenzylketone (DBK) in aqueous media at 300°C and 700 bars for durations up to several days [1], and found that many of the reaction products arise from coupling of benzyl and related radicals generated through homolytic bond cleavage of DBK. In the present work, we find that in situ photochemical generation of the radicals can provide independent evidence for radical intermediates in the <span class="hlt">hydrothermal</span> reaction of DBK, yielding valuable insights into the thermal reactions. <span class="hlt">Hydrothermal</span> photochemical experiments of DBK were conducted in water in sealed fused silica glass tubes at 300°C and 86 bars under UV irradiation for minutes. The short timescale of the experiments allows the primary radical coupling products of DBK to be generated and identified, and their follow-up reactions to be monitored directly. The primary <span class="hlt">hydrothermal</span> photolysis products include toluene, bibenzyl, a three-benzene-ring product (with isomers), and two four-benzene-ring products (with isomers), which represent a much simpler version of the products obtained through thermal reactions under similar conversions. Most of the observed photolysis products were identical to the ones in the thermal reactions, and those not observed in thermal reactions were found to be the short-lived precursors of the thermal products. As an example, the transformation of one four-ring product to the other was attained and monitored by experiments in which <span class="hlt">hydrothermal</span> photolysis of DBK was followed by thermolysis at 300°C for a further few hours. The transformation steps included dehydration and isomerization, which were known to be thermodynamically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Geo....21..499T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Geo....21..499T"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> vents in Lake Tanganyika, East African, Rift system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tiercelin, Jean-Jacques; Pflumio, Catherine; Castrec, Maryse; Boulégue, Jacques; Gente, Pascal; Rolet, Joël; Coussement, Christophe; Stetter, Karl O.; Huber, Robert; Buku, Sony; Mifundu, Wafula</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 °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 NaHCO3-enriched fluid similar to the NaHCO3 thermal fluids from lakes Magadi and Bogoria in the eastern branch off 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 off 219 and 179 °C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa</em> mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130 °N normal-dextral faults that intersect the north- south major rift trend. The source 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.</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/2001AGUFMOS11A0347L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFMOS11A0347L"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Alteration in the PACMANUS <span class="hlt">Hydrothermal</span> Field: Implications From Secondary Mineral Assemblages and Mineral Chemistry, OPD Leg 193</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lackschewitz, K. S.; Kummetz, M.; Kummetz, M.; Ackermand, D.; Botz, R.; Devey, C. W.; Singer, A.; Stoffers, P.</p> <p>2001-12-01</p> <p>Leg 193 of the Ocean Drilling Program investigated the subsurface nature of the active PACMANUS <span class="hlt">hydrothermal</span> field in the Manus backarc basin near Papua New Guinea. Drilling in different areas on the felsic neovolcanic Pual Ridge, including the high-temperature black smoker complex of Roman Ruins and the low-temperature Snowcap <span class="hlt">site</span> with diffusive discharge yielded a complex alteration history with a regional primary alteration being overprinted by a secondary mineralogy. The intense <span class="hlt">hydrothermal</span> alteration at both <span class="hlt">sites</span> shows significant differences in the secondary mineralogy. At Roman Ruins, the upper 25 m of <span class="hlt">hydrothermally</span> altered rocks are characterized by a rapid change from secondary cristobalite to quartz, implying a high temperature gradient. From 10 to 120 mbsf the clay mineralogy is dominated by illite and chlorite. The chlorite formation temperature calculated from oxygen isotope data lies at 250° C in 116 mbsf which is similar to the present fluid outflow temperatures of 240-250° C (Douville et al., 1999, Geochim. Cosmochim. Acta, 63, 627-643). Drilling in the Snowcap field recovered evidence for several stages of <span class="hlt">hydrothermal</span> alteration. Between 50 and 150 mbsf, cristobalite and chlorite are the most abundant alteration minerals while <span class="hlt">hydrothermal</span> pyrophyllite becomes abundant in some places At 67 mbsf, the isotopic composition of pyrophyllite gives a temperature for ist formation at 260° C whereas at 77 and 116 mbsf the pyrophyllite displays the highest temperatures of formation (>300° C). These temperatures are close to the maximum measured borehole temperatures of 313° C. The appearance of assemblages of chlorite, chlorite-vermiculite, chlorite-vermiculite-smectite and illite-smectite as well as the local development of corrensite below 150 mbsf suggests that the alteration at Snowcap may be more complex than that beneath Roman Ruins. Detailed geochemical studies of the authigenic clay mineral phases will provide further insights into the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.B14E..06A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.B14E..06A&link_type=ABSTRACT"><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://adsabs.harvard.edu/abs/2015GGG....16.3716S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.3716S"><span id="translatedtitle">Fluid circulation and carbonate vein precipitation in the footwall of an oceanic core complex, Ocean Drilling Program <span class="hlt">Site</span> 175, 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>Schroeder, Tim; Bach, Wolfgang; Jöns, Niels; Jöns, Svenja; Monien, Patrick; Klügel, Andreas</p> <p>2015-10-01</p> <p>Carbonate veins recovered from the mafic/ultramafic footwall of an oceanic detachment fault on the Mid-Atlantic Ridge record multiple episodes of fluid movement through the detachment and secondary faults. High-temperature (˜75-175°C) calcite veins with elevated REE contents and strong positive Eu-anomalies record the mixing of up-welling <span class="hlt">hydrothermal</span> fluids with infiltrating seawater. Carbonate precipitation is most prominent in olivine-rich troctolite, which also display a much higher degree of greenschist and sub-greenschist alteration relative to gabbro and diabase. Low-temperature calcite and aragonite veins likely precipitated from oxidizing seawater that infiltrated the detachment fault and/or within secondary faults late or post footwall denudation. Oxygen and carbon isotopes lie on a mixing line between seawater and <span class="hlt">Logatchev</span>-like <span class="hlt">hydrothermal</span> fluids, but precipitation temperatures are cooler than would be expected for isenthalpic mixing, suggesting conductive cooling during upward flow. There is no depth dependence of vein precipitation temperature, indicating effective cooling of the footwall via seawater infiltration through fault zones. One sample contains textural evidence of low-temperature, seawater-signature veins being cut by high-temperature, <span class="hlt">hydrothermal</span>-signature veins. This indicates temporal variability in the fluid mixing, possibly caused by deformation-induced porosity changes or dike intrusion. The strong correlation between carbonate precipitation and olivine-rich troctolites suggests that the presence of unaltered olivine is a key requirement for carbonate precipitation from seawater and <span class="hlt">hydrothermal</span> fluids. Our results also suggest that calcite-talc alteration of troctolites may be a more efficient CO2 trap than serpentinized peridotite.</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://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/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/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/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://ntrs.nasa.gov/search.jsp?R=20040065880&hterms=hydrothermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dhydrothermal','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040065880&hterms=hydrothermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dhydrothermal"><span id="translatedtitle">Starting Conditions for <span class="hlt">Hydrothermal</span> Systems Underneath Martian Craters: Hydrocode Modeling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pierazzo, E.; Artemieva, N. A.; Ivanov, B. A.</p> <p>2004-01-01</p> <p>Mars is the most Earth-like of the Solar System s planets, and the first place to look for any sign of present or past extraterrestrial life. Its surface shows many features indicative of the presence of surface and sub-surface water, while impact cratering and volcanism have provided temporary and local surface heat sources throughout Mars geologic history. Impact craters are widely used ubiquitous indicators for the presence of sub-surface water or ice on Mars. In particular, the presence of significant amounts of ground ice or water would cause impact-induced <span class="hlt">hydrothermal</span> alteration at Martian impact <span class="hlt">sites</span>. The realization that <span class="hlt">hydrothermal</span> systems are possible <span class="hlt">sites</span> for the origin and early evolution of life on Earth has given rise to the hypothesis that <span class="hlt">hydrothermal</span> systems may have had the same role on Mars. Rough estimates of the heat generated in impact events have been based on scaling relations, or thermal data based on terrestrial impacts on crystalline basements. Preliminary studies also suggest that melt sheets and target uplift are equally important heat sources for the development of a <span class="hlt">hydrothermal</span> system, while its lifetime depends on the volume and cooling rate of the heat source, as well as the permeability of the host rocks. We present initial results of two-dimensional (2D) and three-dimensional (3D) simulations of impacts on Mars aimed at constraining the initial conditions for modeling the onset and evolution of a <span class="hlt">hydrothermal</span> system on the red planet. Simulations of the early stages of impact cratering provide an estimate of the amount of shock melting and the pressure-temperature distribution in the target caused by various impacts on the Martian surface. Modeling of the late stage of crater collapse is necessary to characterize the final thermal state of the target, including crater uplift, and distribution of the heated target material (including the melt pool) and hot ejecta around the crater.</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('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://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/2014PNAS..11116654F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PNAS..11116654F"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitzsimmons, Jessica N.; Boyle, Edward A.; Jenkins, William J.</p> <p>2014-11-01</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).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=321305','PMC'); return false;" href="http://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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015E%26PSL.431..173E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015E%26PSL.431..173E&link_type=ABSTRACT"><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> <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/1995GMS....91..369L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995GMS....91..369L"><span id="translatedtitle">Chemical and biochemical transformations in <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>Lilley, Marvin D.; Feely, Richard A.; Trefry, John H.</p> <p></p> <p><span class="hlt">Hydrothermal</span> plumes integrate the heat and mass flux originating at seafloor <span class="hlt">hydrothermal</span> vents thereby providing both a means of detecting <span class="hlt">hydrothermal</span> activity and estimating <span class="hlt">hydrothermal</span> fluxes. Many chemical species are introduced into the deep sea via <span class="hlt">hydrothermal</span> plumes (Figure 1) in concentrations many orders of magnitude higher than that existing in background seawater (e.g. H2, CH4 3He, Mn, Fe) while others are scavenged from seawater by <span class="hlt">hydrothermal</span> particles (e.g. PO4-3, V, As, rare earth elements, Th). Dilution by entrainment of background seawater in the buoyant portion of the plume is very rapid (see chapters by Lupton and McDuff, this volume) such that the <span class="hlt">hydrothermal</span> component in the near-field portion of the neutrally buoyant plume represents only about 0.01% of the mixture. Nevertheless, chemical tracers such as 3He, CH4, and Mn are widely utilized in addition to temperature, salinity, and light transmission anomalies to detect <span class="hlt">hydrothermal</span> venting and to draw inferences about the nature of the underlying geochemistry of the <span class="hlt">hydrothermal</span> system. Many other chemical tracers can be utilized during plume studies to provide additional information about the nature of the venting. These include particles, H2, Al, and radioisotopes, among others.</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/cgi-bin/nph-data_query?bibcode=2009AGUFM.T23A1880N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFM.T23A1880N&link_type=ABSTRACT"><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/2001AGUFM.T52A0923M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.T52A0923M"><span id="translatedtitle">First Survey For Submarine <span class="hlt">Hydrothermal</span> Vents In NE Sulawesi, Indonesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McConachy, T.; Binns, R.; Permana, H.</p> <p>2001-12-01</p> <p>The IASSHA-2001 cruise (Indonesia-Australia Survey for Submarine <span class="hlt">Hydrothermal</span> Activity) was successfully conducted from June 1 to June 29 on board Baruna Jaya VIII. Preliminary results are reported of the first expedition to locate and study submarine <span class="hlt">hydrothermal</span> activity in north east Sulawesi. Leg A focussed on Tomini Bay, a virtually unexplored Neogene sedimentary basin. Its objective was to test whether modern sediment-hosted <span class="hlt">hydrothermal</span> activity occurred on the sea floor. The results of new bathymetric mapping, sediment coring and CTD/transmissometer hydrocasts negate the likely presence in central Tomini Bay of large-scale modern analogues of <span class="hlt">hydrothermal</span> massive sulfide environments involving <span class="hlt">hydrothermal</span> venting of basinal or magma-derived fluids into reduced sediments. It is possible that the "heat engine" required to drive circulation of basinal and <span class="hlt">hydrothermal</span> fluids is today too weak. Surveys around Colo volcano indicate that it may be in its final stage of evolution. Leg B studied the arc and behind-arc sectors of the Sangihe volcanic island chain extending northwards from Quaternary volcanoes on the northeastern tip of Sulawesi's North Arm, near Manado. West of the main active chain and extending northwards from Manado there is a subparallel ridge surmounted by a number of high (>2000 m) seamounts of uncertain age. Fifteen relatively high-standing submarine edifices were crossed during this leg, of which nine were tested for <span class="hlt">hydrothermal</span> activity by hydrocast and dredging. Eight <span class="hlt">sites</span> were known from previous bathymetric surveys, and seven are new discoveries made by narrow-beam or multibeam echo sounding. Two submarine edifices at least 1000 m high were discovered in the strait immediately north of Awu volcano on Sangihe Island. One, with crest at 206 m, is surrounded by a circular platform 300m deep which we infer to be a foundered fringing reef to a formerly emergent island. The other, lacking such a platform, appears relatively young and may be</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> </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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4491839','PMC'); return false;" href="http://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="http://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://adsabs.harvard.edu/abs/2015NatCo...6E7567W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatCo...6E7567W"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winslow, Dustin M.; Fisher, Andrew T.</p> <p>2015-06-01</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.</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/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/2010AGUFMOS33F..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS33F..05M"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Vents at 5000m on the Mid-Cayman Rise: The Deepest and Hottest <span class="hlt">Hydrothermal</span> Systems Yet Discovered!</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murton, B. J.; Connelly, D. P.; Copley, J. T.; Stansfield, K. L.; Tyler, P. A.; Cruise Jc044 Sceintific Party</p> <p>2010-12-01</p> <p>This contribution describes the geological setting of <span class="hlt">hydrothermal</span> activity within the Mid- Cayman Rise (MCR) using data acquired during cruise JC044 (MAR-APR 2010) from the deep-towed sidescan sonar TOBI, AUV Autosub6000 and the ROTV HyBIS. The 110 km-long Mid- Cayman Rise (MCR), located within Caribbean Sea, is the deepest spreading centre known, reaching over 6000m. Hence it poses an end-member of extreme depth for <span class="hlt">hydrothermal</span> circulation. Accretion of new volcanic crust is focused within two ridge segments, to the north and south of a centrally located massif of peridotite and gabbro. Following earlier indications of <span class="hlt">hydrothermal</span> plumes (German et al., in 2009), we discovered two high-temperature <span class="hlt">hydrothermal</span> system: one at a depth of 5000m in the neovolcanic zone of the northern segment, and another at 2300m on the flanks of the MCR. These <span class="hlt">sites</span> show contrasting styles of fluid venting, mineralisation, geological setting and host rock interaction. At 5000m-depth, the ultra-deep vent <span class="hlt">site</span> forms the deepest <span class="hlt">hydrothermal</span> system known. Venting is focused at the western side of a 100m diameter, 30m high mound, while inactive sulphides extend eastwards for at least 800m. Fluids discharge from clusters of chimneys whose location is related to basement faults. Changes in salinity in the venting fluids indicate discharge of a low salinity phase and a brine phase. At 500bar, this is definitive evidence for supercritical fluid emission. We also found the sulphide mineralization to be copper-rich, giving a characteristic green hue to many of the deposits, probably a result of the super-critical state of the vent fluids. A prominent axial volcanic ridge nearby indicates a robust magma supply to the northern MCR segment. Thus it is likely the ultra-deep vent <span class="hlt">site</span> derives its thermal energy from magmatic sources, similar to those thought to underlie other slow-spreading ridge volcanic-hosted vent <span class="hlt">sites</span> (e.g. Broken Spur: MAR). The shallower (2300m) MCR <span class="hlt">hydrothermal</span> vent</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> <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.osti.gov/scitech/biblio/6419211','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6419211"><span id="translatedtitle">Major off-axis <span class="hlt">hydrothermal</span> activity on the northern Gorda Ridge</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rona, P.A. ); Denlinger, R.P. ); Fisk, M.R.; Howard, K.J.; Taghon, G.L. ); Klitgord, K.D. ); McClain, J.S. ); McMurray, G.R. ); Wiltshire, J.C. )</p> <p>1990-06-01</p> <p>The first <span class="hlt">hydrothermal</span> field on the northern Gorda Ridge, the Sea Cliff <span class="hlt">hydrothermal</span> field, was discovered and geologic controls of <span class="hlt">hydrothermal</span> activity in the rift valley were investigated on a dive series using the DSV Sea Cliff. The Sea Cliff <span class="hlt">hydrothermal</span> field was discovered where predicted at the intersection of axis-oblique and axis-parallel faults at the south end of a linear ridge at mid-depth (2700 m) on on the east wall. Preliminary mapping and sampling of the field reveal: a setting nested on nearly sediment-free fault blocks 300 m above the rift valley floor 2.6 km from the axis; a spectrum of venting types from seeps to black smokers; high conductive heat flow estimated to be equivalent to the convective flux of multiple black smokers through areas of the sea floor sealed by a caprock of clastic breccia primarily derived from basalt with siliceous cement and barite pore fillings; and a vent biota with Juan de Fuca Ridge affinities. These findings demonstrate the importance of off-axis <span class="hlt">hydrothermal</span> activity and the role of the intersection of tectonic lineations in controlling <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> at sea-floor spreading centers.</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="http://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('http://adsabs.harvard.edu/abs/1996E%26PSL.142..261G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996E%26PSL.142..261G"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> plumes at the Rodriguez triple junction, 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>Gamo, Toshitaka; Nakayama, Eiichiro; Shitashima, Kiminori; Isshiki, Kenji; Obata, Hajime; Okamura, Kei; Kanayama, Shinji; Oomori, Tamotsu; Koizumi, Takayuki; Matsumoto, Satoshi; Hasumoto, Hiroshi</p> <p>1996-07-01</p> <p>Water column anomalies of light transmission, Mn, Fe, Al and CH 4 concentrations were searched in the central, southeastern and southwestern Indian Ridge segments centered on the Rodriguez Triple Junction (RTJ) (˜25°32'S, ˜70°02'E), for the purpose of locating <span class="hlt">hydrothermally</span> active areas, in July to August 1993. We found an active zone in the central Indian Ridge segment (25°18-20'S) approximately 12 miles north of the RTJ, where significant <span class="hlt">hydrothermal</span> plumes were observed at 2,200-2,400 m depth. Intensive tow-yo observations using a CTD rosette multi-sampling system equipped with a transmissometer revealed that the plumes show temporal as well as spatial variations. Discrete water samples within the plumes were enriched in Mn, Fe, and CH 4, with maximum concentrations of 9.8 n M, 40.2 n M and 3.3 n M, respectively. Judging from the spatial and chemical characteristics of the plumes, especially from transmission anomalies and C/H 4Mn ratios, we speculate that the <span class="hlt">hydrothermal</span> venting <span class="hlt">site</span> might be not in the rift valley but on the eastern off-axis zone, several miles distant from the rift valley.</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('http://www.osti.gov/scitech/biblio/22309020','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22309020"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis and characterization of zirconia based catalysts</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Caillot, T. Salama, Z.; Chanut, N.; Cadete Santos Aires, F.J.; Bennici, S.; Auroux, A.</p> <p>2013-07-15</p> <p>In this work, three equimolar mixed oxides ZrO{sub 2}/CeO{sub 2}, ZrO{sub 2}/TiO{sub 2}, ZrO{sub 2}/La{sub 2}O{sub 3} and a reference ZrO{sub 2} have been synthesized by <span class="hlt">hydrothermal</span> method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH{sub 3} and SO{sub 2} probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, <span class="hlt">hydrothermal</span> synthesis leads to catalysts with higher surface area and with better acid–base properties than classical coprecipitation method. Both Lewis and Brønsted acid <span class="hlt">sites</span> are present on the surface of the mixed oxides. Compared to the other samples, the ZrO{sub 2}/TiO{sub 2} material appears to be the best candidate for further application in acid–base catalysis. - Graphical abstract: Mesoporous amorphous phase with a high surface area of titania zirconia mixed oxide obtained by <span class="hlt">hydrothermal</span> preparation. - Highlights: • Three zirconia based catalysts and a reference were prepared by <span class="hlt">hydrothermal</span> synthesis. • Mixed oxides present larger surface areas than the reference ZrO{sub 2}. • ZrO{sub 2}/TiO{sub 2} catalyst presents a mesoporous structure with high surface area. • ZrO{sub 2}/TiO{sub 2} catalyst presents simultaneously strong acidic and basic properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3250503','PMC'); return false;" href="http://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://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> </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('http://adsabs.harvard.edu/abs/2014RvGeo..52..375H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RvGeo..52..375H"><span id="translatedtitle">Dynamics of the Yellowstone <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>Hurwitz, Shaul; Lowenstern, Jacob B.</p> <p>2014-09-01</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://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://www.osti.gov/scitech/biblio/932419','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/932419"><span id="translatedtitle">Catalytic <span class="hlt">Hydrothermal</span> Gasification 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>2008-05-06</p> <p>A recent development in biomass gasification is the use of a pressurized water processing environment in order that drying of the biomass can be avoided. This paper reviews the research undertaken developing this new option for biomass gasification. This review does not cover wet oxidation or near-atmospheric-pressure steam-gasification of biomass. Laboratory research on <span class="hlt">hydrothermal</span> gasification of biomass focusing on the use of catalysts is reviewed here, and a companion review focuses on non-catalytic processing. Research includes liquid-phase, sub-critical processing as well as super-critical water processing. The use of heterogeneous catalysts in such a system allows effective operation at lower temperatures, and the issues around the use of catalysts are presented. This review attempts to show the potential of this new processing concept by comparing the various options under development and the results of the research.</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('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://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="http://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://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('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://www.ncbi.nlm.nih.gov/pubmed/9408952','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9408952"><span id="translatedtitle">Primary structure of the common polypeptide chain b from the multi-hemoglobin system of the <span class="hlt">hydrothermal</span> vent tube worm Riftia pachyptila: an insight on the sulfide binding-<span class="hlt">site</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zal, F; Suzuki, T; Kawasaki, Y; Childress, J J; Lallier, F H; Toulmond, A</p> <p>1997-12-01</p> <p>The deep-sea tube worm Riftia pachyptila Jones possesses a multi-hemoglobin system with three different extracellular Hbs: two dissolved in the vascular blood, V1 (ca. 3,500 kDa) and V2 (ca. 400 kDa), and one in the coelomic fluid, C1 (ca. 400 kDa). V1 Hb consists of four heme-containing, globin chains (b-e) and four linker chains (L1-L4). V2 and C1 Hbs are exclusively built from globin chains, six for V2 (a-f) and five for C1 (a-e). The complete amino acid sequence of the isolated monomeric globin chain b, common to all Riftia Hbs, has been determined by automated Edman degradation sequencing of the peptides derived by digestion with trypsin, chymotrypsin, thermolysin, and CNBr. This polypeptide chain is composed of 144 amino acid residues, providing a M(r) of 16, 135.0 Da. Moreover, the primary sequence of chain b revealed 3 Cys residues at position 4, 75, and 134. Cys-4 and Cys-134 are located at positions where an intra-chain disulfide bridge is formed in all annelid, vestimentiferan, or pogonophoran chains, but Cys-75 is located at a unique position only found in three globin chains belonging to Lamellibrachia and Oligobrachia, a vestimentiferan and a pogonophoran. In both groups, Hbs can bind sulfide reversibly to fuel the chemosynthetic process of the symbiotic bacteria they harbor. Sulfide-binding experiments performed on purified Hb fractions (i.e., V1, V2, and C1 Hbs) suggest that free Cys residues on globin chains, and the numerous Cys found in linker chains, as determined previously by ESI-MS, may be the sulfide binding-<span class="hlt">sites</span>. Blocking the free Cys by N-ethylmaleimide, we confirmed that free cysteines were involved in sulfide-binding but did not account for the whole sulfide-binding capacity of V1 Hb. Furthermore, a phylogenetic tree was constructed from 18 globin-like chains of annelid, vestimentiferan, and pogonophoran extracellular Hbs to clarify the systematic position of tubeworms. Riftia chain b clearly belongs to the "strain A" family with 30 to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13B1746S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13B1746S"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Activity Along Multiple Ridge Segments of the Northern Central Indian Ridge, 8°-17°S</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Son, J.; Kim, J.; Pak, S.; Son, S.; Moon, J.; Baker, E. T.</p> <p>2012-12-01</p> <p>We report the first systematic <span class="hlt">hydrothermal</span> plume surveys conducted on the northern Central Indian Ridge (CIR, 8°-17°S), a slow spreading ridge with rates between ~35 and 40 mm/yr, during the CIR research program of KORDI between 2009 and 2011. Using a combined CTD/Miniature Autonomous Plume Recorder (MAPR) package we occupied 208 vertical casts and 82 tows along seven segments of the CIR totaling ~700 km of ridge length to estimate the frequency of <span class="hlt">hydrothermal</span> activity on this slow-spreading ridge. Evidence for <span class="hlt">hydrothermal</span> activity was found on each of the seven segments, with most plumes found between 3000 and 3500 m. Using only stations within the rift valley, the estimated value of plume incidence (ph=0.19) coincides with the global trend between the spatial density of <span class="hlt">hydrothermal</span> plumes and full-spreading rate (an indicator of magmatic budget). However, there are also indications of possible discharge from <span class="hlt">hydrothermal</span> activity or serpentinization from the ridge flanks (possible ocean core complexes), as has been observed along the Mid-Atlantic Ridge. For example, some <span class="hlt">sites</span> show methane anomalies unaccompanied by any optical anomaly. Our preliminary results support the increasing role of tectonic control on <span class="hlt">hydrothermal</span> activity as spreading rates decrease. Further examination of the plume signals, combined with chemical composition of sampled water and geological data, will provide valuable insights into <span class="hlt">hydrothermal</span> activity on slow spreading ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1112090D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1112090D"><span id="translatedtitle">The relationships between volcanism, tectonism and <span class="hlt">hydrothermal</span> activity on the Mid-Atlantic Ridge south of the equator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Devey, C. W.; German, C. R.; Haase, K. M.; Lackschewitz, K. S.; Melchert, B.; Connelly, D.; Parson, L. M.</p> <p>2009-04-01</p> <p>Using data from the complete bathymetric and side-scan (TOBI) coverage of the Mid-Atlantic Ridge 2-14 °S collected since 2004 in conjunction with the results of extensive prospecting for <span class="hlt">hydrothermal</span> systems in this area we attempt to formulate a general model for the interplay between volcanism, tectonics and <span class="hlt">hydrothermalism</span> on a slow-spreading ridge. The model defines three basic types of ridge morphology with specific <span class="hlt">hydrothermal</span> characteristics: (a) A deep, tectonically-dominated rift valley where <span class="hlt">hydrothermalism</span> is seldom associated with volcanism and much more likely confined to long-lived bounding faults (b) a shallower, segment-centre bulge where a combination of repeated magmatic activity and tectonism results in repeated, possibly temporally overlapping periods of <span class="hlt">hydrothermal</span> activity on the ridge axis and (c) a very shallow, inflated axis beneath which temperatures in all but the uppermost crust are so high that deformation is ductile, inhibiting the formation of high-porosity deep fractures and severely depressing <span class="hlt">hydrothermal</span> circulation. This model is used together with predicted bathymetry to provide forecasts of the best places to look for <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in the remaining unexplored regions of the South Atlantic</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/2006AGUFM.V13A0637H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V13A0637H"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Manganese Mineralization Near the Samoan Hotspot</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hein, J. R.; Staudigel, H.; Koppers, A.; Hart, S. R.; Dunham, R.</p> <p>2006-12-01</p> <p>The thickest beds of <span class="hlt">hydrothermal</span> manganese oxides recovered to date from the global ocean were collected from a volcanic cone in the south Pacific. In April 2005, samples were dredged aboard the R.V. Kilo Moana from a volcanic cone on the lower flank of Tulaga seamount (about 2,700 m water depth; 14° 39.222' S; 170° 1.730' W), located 115 km SW of Vailulu'u, the volcanically and <span class="hlt">hydrothermally</span> active center of the Samoan hotspot. Additional <span class="hlt">hydrothermal</span> manganese samples were collected off Ofu Island (dredge Alia 107), 72 km to the WSW of Vailulu'u. Manganese-oxide beds up to 9 cm thick are composed of birnessite and 10 Å manganates. Some layers consist of Mn-oxide columnar structures 4 cm long and 1 cm wide, which have not been described previously. The mean Mn and Fe contents of 18 samples are 51 weight percent and 0.76 weight percent, respectively. Elevated concentrations of Li (mean 0.11 wt. percent) are indicators of a <span class="hlt">hydrothermal</span> origin, and distinguishes these samples, along with the high Mn and low Fe contents, from hydrogenetic Fe-Mn crusts. Other enriched elements include Ba (mean 0.14 percent), Cu (249 ppm), Mo (451 ppm), Ni (400 ppm), Zn (394 ppm), V (214 ppm), and W (132 ppm). Chondrite-normalized REE patterns show large negative Ce anomalies and LREE enrichments, both characteristic of <span class="hlt">hydrothermal</span> Mn deposits. Small negative Eu anomalies are not typical of <span class="hlt">hydrothermal</span> deposits and can be explained either by the absence of leaching of plagioclase by the <span class="hlt">hydrothermal</span> fluids or by the precipitation of Eu-rich minerals, such as barite and anhydrite, at depth. The high base-metal contents indicate that sulfides are not forming deeper in the <span class="hlt">hydrothermal</span> system or that such deposits are being leached by the ascending fluids. Textures of the thickest Mn deposits indicate that the Mn oxides formed below the seabed from ascending fluids during multiple phases of waxing and waning <span class="hlt">hydrothermal</span> pulses. The deposits were later exposed at the seafloor by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.V43B2880G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.V43B2880G&link_type=ABSTRACT"><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('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://adsabs.harvard.edu/abs/2007EOSTr..88...53C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007EOSTr..88...53C"><span id="translatedtitle">Hazards From <span class="hlt">Hydrothermally</span> Sealed Volcanic Conduits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christenson, Bruce W.; Werner, Cynthia A.; Reyes, Agnes G.; Sherburn, Steve; Scott, Bradley J.; Miller, Craig; Rosenburg, Michael J.; Hurst, Anthony W.; Britten, Karen A.</p> <p>2007-01-01</p> <p>The 17 March 2006 eruption from Raoul Island (Kermadec arc, north of New Zealand) is interpreted as a magmatic-<span class="hlt">hydrothermal</span> event triggered by shaking associated with a swarm of local earthquakes. The eruption, which tragically claimed the life of New Zealand Department of Conservation Ranger Mark Kearney, occurred without significant volcanic seismicity or any of the precursory responses the volcanic <span class="hlt">hydrothermal</span> system exhibited prior to a similarly sized eruption in 1964.</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> </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.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://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/cgi-bin/nph-data_query?bibcode=2016EGUGA..1816742H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1816742H&link_type=ABSTRACT"><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/cgi-bin/nph-data_query?bibcode=2009DSRII..56.1577E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009DSRII..56.1577E&link_type=ABSTRACT"><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=seawater+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dseawater%2Bchemistry','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950037876&hterms=seawater+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dseawater%2Bchemistry"><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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23647923','PUBMED'); return false;" href="http://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="http://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. PMID:23647923</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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JVGR..314..156S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JVGR..314..156S&link_type=ABSTRACT"><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://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/2015NatGe...8..856H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatGe...8..856H"><span id="translatedtitle">Efficient removal of recalcitrant deep-ocean dissolved organic matter 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>Hawkes, Jeffrey A.; Rossel, Pamela E.; Stubbins, Aron; Butterfield, David; Connelly, Douglas P.; Achterberg, Eric P.; Koschinsky, Andrea; Chavagnac, Valérie; Hansen, Christian T.; Bach, Wolfgang; Dittmar, Thorsten</p> <p>2015-11-01</p> <p>Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood. Hot <span class="hlt">hydrothermal</span> circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent <span class="hlt">sites</span> in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through <span class="hlt">hydrothermal</span> systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through <span class="hlt">hydrothermal</span> vents with fluid temperatures of 212-401 °C. In laboratory experiments, where we heated samples to 380 °C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural <span class="hlt">hydrothermal</span> systems, and that its maximum lifetime is constrained by the timescale of <span class="hlt">hydrothermal</span> cycling, at about 40 million years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AsBio...1...71N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AsBio...1...71N"><span id="translatedtitle">Location and Sampling of Aqueous and <span class="hlt">Hydrothermal</span> Deposits in Martian Impact Craters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newsom, Horton E.; Hagerty, Justin J.; Thorsos, Ivan E.</p> <p>2001-03-01</p> <p>Do large craters on Mars represent <span class="hlt">sites</span> that contain aqueous and <span class="hlt">hydrothermal</span> deposits that provide clues to astrobiological processes? Are these materials available for sampling in large craters? Several lines of evidence strongly support the exploration of large impact craters to study deposits important for astrobiology. The great depth of impact craters, up to several kilometers relative to the surrounding terrain, can allow the breaching of local aquifers, providing a source of water for lakes and <span class="hlt">hydrothermal</span> systems. Craters can also be filled with water from outflow channels and valley networks to form large lakes with accompanying sedimentation. Impact melt and uplifted basement heat sources in craters >50 km in diameter should be sufficient to drive substantial <span class="hlt">hydrothermal</span> activity and keep crater lakes from freezing for thousands of years, even under cold climatic conditions. Fluid flow in <span class="hlt">hydrothermal</span> systems is focused at the edges of large planar impact melt sheets, suggesting that the edge of the melt sheets will have experienced substantial <span class="hlt">hydrothermal</span> alteration and mineral deposition. <span class="hlt">Hydrothermal</span> deposits, fine-grained lacustrine sediments, and playa evaporite deposits may preserve evidence for biogeochemical processes that occurred in the aquifers and craters. Therefore, large craters may represent giant Petri dishes for culturing preexisting life on Mars and promoting biogeochemical processes. Landing <span class="hlt">sites</span> must be identified in craters where access to the buried lacustrine sediments and impact melt deposits is provided by processes such as erosion from outflow channels, faulting, aeolian erosion, or excavation by later superimposed cratering events. Very recent gully formation and small impacts within craters may allow surface sampling of organic materials exposed only recently to the harsh oxidizing surface environment.</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/2008AGUFM.B51D0428F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.B51D0428F"><span id="translatedtitle">Diversity of Archaeal Consortia in an Arsenic-Rich <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>Franks, M.; Bennett, P.; Omelon, C.; Engel, A.</p> <p>2008-12-01</p> <p>Characterizing microbial communities within their geochemical environment is essential to understanding microbial distribution and microbial adaptations to extreme physical and chemical conditions. The <span class="hlt">hydrothermal</span> waters at El Tatio geyser field demonstrate extreme conditions, with water at local boiling (85°C), arsenic concentrations at 0.5 mM, and inorganic carbon concentrations as low as 0.02mM. Yet many of El Tatio's hundred plus <span class="hlt">hydrothermal</span> features are associated with extensive microbial mat communities. Recent work has shown phylogenetic variation in the communities that correlates to variations in water chemistry between features. MPN analysis indicates variations in metabolic function between <span class="hlt">hydrothermal</span> features, such as the ability of the community to fix nitrogen, and the presence of methanogens within the community. Methanogenic archaea, which are typical of <span class="hlt">hydrothermal</span> environments, are found in very few of the sampled <span class="hlt">hydrothermal</span> features at El Tatio. MPN enumeration shows that nonspecific microbial mat samples from <span class="hlt">sites</span> with dissolved methane contain 106 cells of methanogenic archaea per gram while non-specific samples from <span class="hlt">sites</span> lacking dissolved methane contain 100 cells per gram or less. An acetylene assay showed evidence for nitrogen fixation in a sample associated with methanogenesis, but microbial transformation of acetylene to ethylene did not occur in non-methanogenic <span class="hlt">sites</span>. More specific sampling of microbial mats indicates that methanogenic archaea are dominated by microorganisms within the genus Methanospirillum and Methanobrevibacter. These microbes are associated with a number of unclassified archaea in the class Thermoplasmata Halobacteriales, and unclassifiec Crenarchaeota. In addition, preliminary results include an unclassified Thaumarchaeota clone, a member of the recently proposed third archaeal phylum Thaumarchaeota. Nonspecific microbial mat sample from a non- methanogenic <span class="hlt">site</span> included only Crenarchaeal clones within the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012GGG....13.AF04L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012GGG....13.AF04L&link_type=ABSTRACT"><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/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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFM.B32B..02P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFM.B32B..02P&link_type=ABSTRACT"><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/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> </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://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://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://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> <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://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/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/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://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://ntrs.nasa.gov/search.jsp?R=20040141979&hterms=lipid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dlipid','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040141979&hterms=lipid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dlipid"><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://www.ncbi.nlm.nih.gov/pubmed/21497436','PUBMED'); return false;" href="http://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="http://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. PMID:21497436</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/2015ApSS..357.1911J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApSS..357.1911J"><span id="translatedtitle"><span class="hlt">Hydrothermally</span> reduced graphene oxide as a supercapacitor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johra, Fatima Tuz; Jung, Woo-Gwang</p> <p>2015-12-01</p> <p>The supercapacitance behavior of <span class="hlt">hydrothermally</span> reduced graphene oxide (RGO) was investigated for the first time. The capacitive behavior of RGO was characterized by using cyclic voltammetry and galvanostatic charge-discharge methods. The specific capacitance of <span class="hlt">hydrothermally</span> reduced RGO at 1 A/g was 367 F/g in 1 M H2SO4 electrolyte, which was higher than that of RGO synthesized via the hydrazine reduction method. The RGO-modified glassy carbon electrode showed excellent stability. After 1000 cycles, the supercapacitance was 107.7% of that achieved in the 1st cycle, which suggests that RGO has excellent electrochemical stability as a supercapacitor electrode material. The energy density of <span class="hlt">hydrothermal</span> RGO reached 44.4 W h/kg at a power density of 40 kW/kg.</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/1995CoMP..122..134B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995CoMP..122..134B"><span id="translatedtitle">Mechanisms of Mg-phyllosilicate formation in a <span class="hlt">hydrothermal</span> system at a sedimented ridge (Middle Valley, Juan de Fuca)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buatier, M. D.; Früh-Green, Gretchen L.; Karpoff, A. M.</p> <p>1995-11-01</p> <p>We present results of a detailed mineralogical and geochemical study of the progressive <span class="hlt">hydrothermal</span> alteration of clastic sediments recovered at ODP <span class="hlt">Site</span> 858 in an area of active <span class="hlt">hydrothermal</span> venting at the sedimented, axial rift valley of Middle Valley (northern Juan de Fuca Ridge). These results allow a characterization of newly formed phyllosilicates and provide constraints on the mechanisms of clay formation and controls of mineral reactions on the chemical and isotopic composition of <span class="hlt">hydrothermal</span> fluids. <span class="hlt">Hydrothermal</span> alteration at <span class="hlt">Site</span> 858 is characterized by a progressive change in phyllosilicate assemblages with depth. In the immediate vent area, at Hole 858B, detrital layers are intercalated with pure <span class="hlt">hydrothermal</span> precipitates at the top of the section, with a predominance of <span class="hlt">hydrothermal</span> phases at depth. Sequentially downhole in Hole 858B, the clay fraction of the pure <span class="hlt">hydrothermal</span> layers changes from smectite to corrensite to swelling chlorite and finally to chlorite. In three pure <span class="hlt">hydrothermal</span> layers in the deepest part of Hole 858B, the clay minerals coexist with neoformed quartz. Neoformed and detrital components are clearly distinguished on the basis of morphology, as seen by SEM and TEM, and by their chemical and stable isotope compositions. Corrensite is characterized by a 24 Å stacking sequence and high Si- and Mg-contents, with Fe/(Fe+Mg) ratio of ≈0.08. We propose that corrensite is a unique, possibly metastable, mineralogical phase and was precipitated directly from seawater-dominated <span class="hlt">hydrothermal</span> fluids. <span class="hlt">Hydrothermal</span> chlorite in Hole 858B has a stacking sequence of 14 Å with Fe/(Fe+Mg) ratios of ≈0.35. The chemistry and structure of swelling chlorite suggest that it is a corrensite/chlorite mixed-layer phase. The mineralogical zonation in Hole 858B is accompanied by a systematic decrease in δ18O, reflecting both the high thermal gradients that prevail at <span class="hlt">Site</span> 858 and extensive sediment-fluid interaction. Precipitation of the Mg</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V21A4712L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V21A4712L"><span id="translatedtitle">Mapping Ground Temperature and Radiant <span class="hlt">Hydrothermal</span> Heat Flux on Mammoth Mountain, CA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lewis, A. J.; Lewicki, J. L.; Hilley, G. E.</p> <p>2014-12-01</p> <p>Quantifying the spatial and temporal variability of ground temperatures and <span class="hlt">hydrothermal</span> heat fluxes in volcanic and geothermal systems is important for monitoring volcanic activity, monitoring the impacts of geothermal development, and assessing resources. We used ground based thermal infrared (TIR) imaging combined with Structure-from-Motion (SfM) photogrammetry to produce high-resolution (cm scale) DEMs over which images of ground temperature and radiant <span class="hlt">hydrothermal</span> heat flux were draped. We apply this methodology to two <span class="hlt">hydrothermal</span> areas (Mammoth Mountain and South Side fumaroles) on Mammoth Mountain, CA, allowing us to image the detailed topography, map the thermal features at each area and assess the spatial relationships between the two efficiently and at high resolution. Mammoth Mountain is a lava-dome complex located on the southwestern rim of Long Valley caldera, CA. Unrest at Mammoth Mountain is currently manifested by seismic swarms, ground deformation, elevated 3He/4He ratios in gases at the Mammoth Mountain fumarole, and large changes in diffuse magmatic CO2 emissions from the five tree kill areas on the volcano flanks. We augment the extensive dataset collected at this <span class="hlt">site</span> over the previous decades by quantifying ground temperatures and <span class="hlt">hydrothermal</span> heat fluxes at the Mammoth Mountain and South Side fumarole <span class="hlt">sites</span>. This was accomplished using a hand-held FLIR T650sc camera that simultaneously acquires visible and TIR images of the study <span class="hlt">site</span>. Daytime and nighttime co-located visible and TIR images were acquired over each study area, and image processing was used to orthorectify and mosaic visible and TIR images, calculate radiant <span class="hlt">hydrothermal</span> heat fluxes, construct 3D imagery of ground surface, overlay maps of ground temperatures and heat fluxes, and establish spatial relationships between topography and heat flow.</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_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://www.ncbi.nlm.nih.gov/pubmed/25244359','PUBMED'); return false;" href="http://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="http://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. PMID:25244359</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016MinDe.tmp...36B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016MinDe.tmp...36B&link_type=ABSTRACT"><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://adsabs.harvard.edu/abs/2013JSSCh.203...79C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSSCh.203...79C"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis and characterization of zirconia based catalysts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caillot, T.; Salama, Z.; Chanut, N.; Cadete Santos Aires, F. J.; Bennici, S.; Auroux, A.</p> <p>2013-07-01</p> <p>In this work, three equimolar mixed oxides ZrO2/CeO2, ZrO2/TiO2, ZrO2/La2O3 and a reference ZrO2 have been synthesized by <span class="hlt">hydrothermal</span> method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH3 and SO2 probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, <span class="hlt">hydrothermal</span> synthesis leads to catalysts with higher surface area and with better acid-base properties than classical coprecipitation method. Both Lewis and Brønsted acid <span class="hlt">sites</span> are present on the surface of the mixed oxides. Compared to the other samples, the ZrO2/TiO2 material appears to be the best candidate for further application in acid-base catalysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5259842','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5259842"><span id="translatedtitle">Sulfur gas geochemical detection of <span class="hlt">hydrothermal</span> systems. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rouse, G.E.</p> <p>1984-01-01</p> <p>The purpose of this investigation was to determine whether a system of exploration using sulfur gases was capable of detecting convecting <span class="hlt">hydrothermal</span> systems. Three surveying techniques were used at the Roosevelt Hot Springs KGRA in Utah. These were (a) a sniffing technique, capable of instantaneous determinations of sulfur gas concentration, (b) an accumulator technique, capable of integrating the sulfur gas emanations over a 30 day interval, and (c) a method of analyzing the soils for vaporous sulfur compounds. Because of limitations in the sniffer technique, only a limited amount of surveying was done with this method. The accumulator and soil sampling techniques were conducted on a 1000 foot grid at Roosevelt Hot Springs, and each sample <span class="hlt">site</span> was visited three times during the spring of 1980. Thus, three soil samples and two accumulator samples were collected at each <span class="hlt">site</span>. The results are shown as averages of three soil and two accumulator determinations of sulfur gas concentrations at each <span class="hlt">site</span>. Soil surveys and accumulator surveys were conducted at two additional KGRA's which were chosen based on the state of knowledge of these <span class="hlt">hydrothermal</span> systems and upon their differences from Roosevelt Hot Springs in an effort to show that the exploration methods would be effective in detecting geothermal reservoirs in general. The results at Roosevelt Hot Springs, Utah show that each of the three surveying methods was capable of detecting sulfur gas anomalies which can be interpreted to be related to the source at depth, based on resistivity mapping of that source, and also correlatable with major structural features of the area which are thought to be controlling the geometry of the geothermal reservoir. The results of the surveys at Roosevelt did not indicate that either the soil sampling technique or the accumulator technique was superior to the other.</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/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://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://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/abs/2003EAEJA....14416R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....14416R"><span id="translatedtitle">Chicxulub: testing for post-impact <span class="hlt">hydrothermal</span> inputs into the Tertiary ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rowe, A.; Wilkinson, J.; Morgan, J.</p> <p>2003-04-01</p> <p>Large terrestrial impacts produce intense fracturing of the crust and large melt sheets, providing ideal conditions for extensive <span class="hlt">hydrothermal</span> circulation. In marine settings, such as Chicxulub, there is the potential for downward penetration of cold seawater, heating by the thermal anomaly at the impact <span class="hlt">site</span> and leaching of metals, prior to buoyancy driven flow back to the surface. There, fluids may undergo venting into the water column. A large proportion of the metals in such vent fluids precipitate close to the <span class="hlt">site</span> of discharge; however, a proportion of the fluid is dispersed as a <span class="hlt">hydrothermal</span> plume. Dissolved and particulate materials (in particular manganese and iron oxyhydroxides) can be carried for several hundreds of kilometers, before falling out to form metal-rich sediments. A series of Tertiary core samples has been obtained from the International Continental Drilling Program at Chicxulub (CSDP). These comprise fine-grained cream coloured carbonate sediments with fine laminations. Transmitted light and cathodoluminescence petrography have been used to carry out a preliminary characterization of the samples. Multi-element analysis has also been undertaken by ICP-AES. Samples were reduced to powder and digested using a nitric-perchloric-hydrofluoric acid attack. Rare earth elements (REE) have been analysed by ICP-MS and solutions were prepared using a modified nitric-perchloric-hydrofluoric acid attack. Geochemical analyses have been carried out to test for characteristic signals of <span class="hlt">hydrothermal</span> input, such as enrichments in Mn, Fe, Cu, Zn, Pb, Mg, Ba, Co, Cr and Ni. The REE are scavenged from seawater onto iron oxide surfaces in the plume; hence anomalous REE concentrations are also indicative of <span class="hlt">hydrothermal</span> addition. Furthermore, the type of anomaly can differentiate between sediments proximal (+ve Eu) distal (-ve Ce) to the vent <span class="hlt">site</span>. The stratigraphic extent of any anomalies can be used to constrain the duration of any post-impact circulation. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1052E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1052E"><span id="translatedtitle">Extensive <span class="hlt">hydrothermal</span> activity in the NE Lau basin revealed by ROV dives</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.; Resing, J. A.; Tebo, B.; Baker, E. T.; Butterfield, D. A.; Chadwick, B.; Davis, R.; de Ronde, C. E. J.; Lilley, M. D.; Lupton, J. E.; Merle, S. G.; Rubin, K. H.; Shank, T. M.; Walker, S. L.; Arculus, R. J.; Bobbitt, A. M.; Buck, N. J.; Caratori Tontini, F.; Crowhurst, P. V.; Mitchell, E.; Olson, E. J.; Ratmeyer, V.; Richards, S.; Roe, K. K.; Kenner-Chavis, P.; Martinez-Lyons, A.; Sheehan, C.; Brian, R.</p> <p>2014-12-01</p> <p>Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These <span class="hlt">sites</span>, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing <span class="hlt">site</span> on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/<span class="hlt">hydrothermal</span> activity in the NE Lau Basin. Chemosynthetic ecosystems at these <span class="hlt">sites</span> range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing <span class="hlt">sites</span> to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the <span class="hlt">hydrothermal</span> systems in this area provides an intriguing template to study the interaction of <span class="hlt">hydrothermal</span> fluid chemistry, chemosynthetic habitats and their geologic underpinning</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V21C2738E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V21C2738E"><span id="translatedtitle">Hyperactive <span class="hlt">hydrothermal</span> activity in the NE Lau basin revealed by ROV dives</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.; Resing, J. A.; Tebo, B.; Baker, E. T.; Butterfield, D. A.; Chadwick, B.; Davis, R.; de Ronde, C. E.; Lilley, M. D.; Lupton, J. E.; Merle, S. G.; Rubin, K. H.; Shank, T. M.; Walker, S. L.; Arculus, R. J.; Bobbitt, A. M.; Buck, N.; Caratori Tontini, F.; Crowhurst, P. V.; Mitchell, E.; Olson, E. J.; Ratmeyer, V.; Richards, S.; Roe, K. K.; Keener, P.; Martinez Lyons, A.; Sheehan, C.; Brian, R.</p> <p>2013-12-01</p> <p>Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These <span class="hlt">sites</span>, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing <span class="hlt">site</span> on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/<span class="hlt">hydrothermal</span> activity in the NE Lau Basin. Chemosynthetic ecosystems at these <span class="hlt">sites</span> range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing <span class="hlt">sites</span> to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the <span class="hlt">hydrothermal</span> systems in this area provides an intriguing template to study the interaction of <span class="hlt">hydrothermal</span> fluid chemistry, chemosynthetic habitats and their geologic underpinning</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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeCoA.173...64J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeCoA.173...64J&link_type=ABSTRACT"><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://www.osti.gov/scitech/servlets/purl/231670','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/231670"><span id="translatedtitle">Garnet phosphors prepared via <span class="hlt">hydrothermal</span> synthesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Phillips, M.L.F.; Walko, R.J.; Shea, L.E.</p> <p>1996-05-01</p> <p>This project studied <span class="hlt">hydrothermal</span> synthesis as a route to producing green-emitting cathodoluminescent phosphorus isostructural with yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, or YAG). Aqueous precipitation of Y, Gd, Al, Ga, and Tb salts produced amorphous gels, which were heated with water at 600 C and 3,200 bar to produce crystalline YAG:Tb, Y{sub 3}Ga{sub 5}O{sub 12}:Tb, Y{sub 3}Al{sub 3}Ga{sub 2}O{sub 12}:Tb, and Gd{sub 3}Ga{sub 5}O{sub 12}:Tb powders. Process parameters were identified that yielded submicron YAG:Tb and Y{sub 3}Ga{sub 5}O{sub 12}:Tb powders without grinding. Cathodoluminescent efficiencies were measured as functions of power density at 600 V, using both the <span class="hlt">hydrothermal</span> garnets and identical phosphor compositions synthesized at high temperatures. Saturation behavior was independent of synthetic technique, however, the <span class="hlt">hydrothermal</span> phosphorus were less susceptible to damage (irreversible efficiency loss) at very high power densities (up to 0.1 W/cm{sup 2}). The fine grain sizes available with <span class="hlt">hydrothermal</span> synthesis make it an attractive method for preparing garnet phosphorus for field emission, projection, and head-up displays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11539585','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11539585"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> systems and the emergence of life.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shock, E L</p> <p>1994-03-01</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. PMID:11539585</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SolE....6.1131G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SolE....6.1131G"><span id="translatedtitle">The <span class="hlt">hydrothermal</span> power of oceanic lithosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grose, C. J.; Afonso, J. C.</p> <p>2015-10-01</p> <p>We have estimated the power of ventilated <span class="hlt">hydrothermal</span> heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of axial <span class="hlt">hydrothermal</span> circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than most previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (< 1 My old) is about 50 % of the total, significantly higher than previous estimates. These new estimates originate from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (a thermal blanketing effect yielding lower heat flow) and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated <span class="hlt">hydrothermal</span> circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of ventilated <span class="hlt">hydrothermal</span> power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and the convective mantle.</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://ntrs.nasa.gov/search.jsp?R=20010091026&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DSulfur','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010091026&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DSulfur"><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> </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/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://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="http://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://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="http://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://ntrs.nasa.gov/search.jsp?R=20040065937&hterms=deep+vent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddeep%2Bvent','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040065937&hterms=deep+vent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddeep%2Bvent"><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('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="http://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://adsabs.harvard.edu/abs/2010E%26PSL.299..310B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010E%26PSL.299..310B"><span id="translatedtitle">Rare earth elements in mussel shells of the Mytilidae family as tracers for hidden and fossil high-temperature <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>Bau, Michael; Balan, Simona; Schmidt, Katja; Koschinsky, Andrea</p> <p>2010-11-01</p> <p>Bathymodiolus mussels of the Mytilidae family live in ecological niches at marine vent <span class="hlt">sites</span> where <span class="hlt">hydrothermal</span> fluids discharge at the seafloor and mix with ambient seawater. We report the first concentration data for rare earth elements and yttrium (REY) of Bathymodiolus shells and of low-temperature diffuse <span class="hlt">hydrothermal</span> fluids venting in their respective habitat at three <span class="hlt">hydrothermal</span> vent fields along the Mid-Atlantic Ridge (MAR) and for littoral Mytilus edulis shells from the western North Atlantic, Dingle Bay, Ireland, and from the southern North Sea, German Bight, Germany. Similar to high-temperature <span class="hlt">hydrothermal</span> solutions expelled in the respective area, the low-temperature diffuse fluids from the <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> display positive Eu anomalies. These indicate that the fluids carry a component previously involved in high-temperature water-rock interaction, as decoupling of Eu from neighbouring REY requires temperatures above about 200 °C. While the Bathymodiolus shells from the <span class="hlt">hydrothermal</span> vent fields reflect these positive Eu anomalies, the littoral M. edulis shells studied for comparison, do not show Eu anomalies, consistent with the lack of any high-temperature <span class="hlt">hydrothermal</span> activity in their coastal environments. Shells of mussels of the Mytilidae family, such as Bathymodiolus and M. edulis, therefore, are archives whose REY distribution can be used as a proxy for the Eu anomaly of the waters in which the mussels grew. Although the Ca carbonate of a mussel shell is precipitated from the extrapallial fluid of the mussel and not directly from seawater, the Eu/Eu* ratio of seawater is not significantly modified under the low-temperature conditions prevailing during vital processes and biomineralization. This allows one to use the positive Eu anomalies in the REY distribution patterns of Bathymodiolus shells as a tracer for hidden or fossil high-temperature <span class="hlt">hydrothermal</span> systems where other indicators of high-temperature <span class="hlt">hydrothermalism</span> are not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864048','PMC'); return false;" href="http://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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013NatSR...3E3487I&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013NatSR...3E3487I&link_type=ABSTRACT"><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('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="http://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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3695286','PMC'); return false;" href="http://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://adsabs.harvard.edu/abs/2015GGG....16.2762E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.2762E"><span id="translatedtitle">Particle dynamics in the rising plume at Piccard <span class="hlt">Hydrothermal</span> Field, Mid-Cayman Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Estapa, M. L.; Breier, J. A.; German, C. R.</p> <p>2015-09-01</p> <p>Processes active in rising <span class="hlt">hydrothermal</span> plumes, such as precipitation, particle aggregation, and biological growth, affect particle size distributions and can exert important influences on the biogeochemical impact of submarine venting of iron to the oceans and their sediments. However, observations to date of particle size distribution within these systems are both limited and conflicting. In a novel buoyant <span class="hlt">hydrothermal</span> plume study at the recently discovered high-temperature (398°C) Piccard <span class="hlt">Hydrothermal</span> Field, Mid-Cayman Rise, we report optical measurements of particle size distributions (PSDs). We describe the plume PSD in terms of a simple, power-law model commonly used in studies of upper and coastal ocean particle dynamics. Observed PSD slopes, derived from spectral beam attenuation and laser diffraction measurements, are among the highest found to date anywhere in the ocean and ranged from 2.9 to 8.5. Beam attenuation at 650 nm ranged from near zero to a rarely observed maximum of 192 m-1 at 3.5 m above the vent. We did not find large (>100 μm) particles that would settle rapidly to the sediments. Instead, beam attenuation was well-correlated to total iron, suggesting the first-order importance of particle dilution, rather than precipitation or dissolution, in the rising plume at Piccard. Our observations at Piccard caution against the assumption of rapid deposition of <span class="hlt">hydrothermal</span>, particulate metal fluxes, and illustrate the need for more particle size and composition measurements across a broader range of <span class="hlt">sites</span>, globally.</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('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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.B13C0630H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.B13C0630H&link_type=ABSTRACT"><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/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/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> <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://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> </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.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/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://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://adsabs.harvard.edu/abs/2002AGUFM.T11C1265R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.T11C1265R"><span id="translatedtitle">Using <span class="hlt">Hydrothermal</span> Plumes and Their Chemical Composition to Identify and Understand <span class="hlt">Hydrothermal</span> Activity at Explorer Ridge</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.; Lebon, G.; Baker, E.; Walker, S.; Nakamura, K.; Silvers, B.</p> <p>2002-12-01</p> <p>During June and July, 2002, an extensive survey of the <span class="hlt">hydrothermal</span> systems of the Explorer Ridge was made aboard the R/V Thomas Thompson. This survey employed hydrocasts and the Autonomous Benthic Explorer (ABE) to locate and map <span class="hlt">hydrothermal</span> vent fields. A total of 28 hydrocasts (17 verticals and 11 tow-yos) were used to search for <span class="hlt">hydrothermal</span> activity from 49.5°N to 50.3°N on the Explorer Ridge. During the hydrocasts continuous measurements were made of conductivity, temperature, pressure, light backscatter, eH, Fe, Mn, and pH. Discrete samples were collected for total dissolved Fe and Mn, methane, pH, total CO2, and particulate matter. Most of the strong <span class="hlt">hydrothermal</span> venting was near the Magic Mountain area of the Explorer Ridge at ~49.76° N, 130.26° W, where strong particulate backscatter signals (~0.130 NTUs) and moderate temperature anomalies (~ 0.05 °C) were detected. The particulate matter causing the backscatter was made up primarily of volatile particulate sulfur (PS) with little to no <span class="hlt">hydrothermal</span> PFe. PS:PFe ratios exceeded 25 in the areas of most intense venting, . These PFe and PS data suggest that the <span class="hlt">hydrothermal</span> Fe, if any, is deposited as sulfide minerals beneath the sea floor and that S is far in excess of Fe in the <span class="hlt">hydrothermal</span> fluids. In the most intense plumes,total dissolvable Fe and Mn were between 20 and 30 nM, pH anomalies exceeded 0.025 pH units (indicating an increase of ~10uM CO2), and methane reached 16nM. These results suggest that the fluids exiting the sea floor are metal-poor and moderately gas-rich.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMNS33A..02N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMNS33A..02N&link_type=ABSTRACT"><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/2007AGUFM.V31C0596I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V31C0596I"><span id="translatedtitle">Pyrite Recrystallization Experiments With Circulating <span class="hlt">Hydrothermal</span> Solution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Isobe, H.; Abe, A.; Tanaka, K.</p> <p>2007-12-01</p> <p>Pyrite is one of the most common sulfide minerals found in <span class="hlt">hydrothermal</span> deposits and sea-floor sediments from <span class="hlt">hydrothermal</span> fumaroles. <span class="hlt">Hydrothermal</span> fluid flow plays an important role in crystallization of sulfide minerals. In this study, we tried to reproduce pyrite crystallization with one-way flowing <span class="hlt">hydrothermal</span> fluid. We designed a circuit circulating <span class="hlt">hydrothermal</span> fluid by thermal convection. A rectangular circuit (42.6 cm by 17.3 cm) of SUS316 pressure tubes with 5 mm in inner diameter was used as a reaction vessel. In the circuit, pyrite dissolves to acidic fluid in upstream region. Then, pyrite will crystallize again in downstream region as temperature decreases. The rectangular plane was held to be 20 degrees inclination to generate thermal convection. One of the long sides of the rectangular was heated by an electric furnace. Starting materials were put in a tube to be heated. Upper half, approximately 20 cm, of the tube was filled with quartz sand. Next quarter was filled with equivalent mass mixture of quartz sand and powdered pyrite crystals. The lowest quarter was filled with mixture of quartz sand, pyrite, anhydrite and sulfur, those mass are equivalent. The solution was a mixture of 0.5mol/l HCl and 3.0mol/l NaCl. Maximum temperature was controlled to approximately 350°C at the center of the heated tube. Experimental durations were up to 9 days. Fluid pressure increased to approximately 6 MPa as heating. After the experiments, the run products were fixed with resin in a sample tube, and vertical sections were observed by SEM. In the run products, pyrite dissolved at the lower part of the starting material. In the upper half of the sample tube, pyrite crystals precipitated on quartz surface. Crystallization density depends on temperature gradient of the fluid. Predominant morphology of the pyrite crystals consists (100) plains. Tiny framboidal aggregates and crystals with (210) plains also occur. In the run products of longer than 3 days run durations</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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4036102','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4036102"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> phase transformation of hematite to magnetite</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>2014-01-01</p> <p>Different phases of iron oxide were obtained by <span class="hlt">hydrothermal</span> treatment of ferric solution at 200°C with the addition of either KOH, ethylenediamine (EDA), or KOH and EDA into the reaction system. As usually observed, the α-Fe2O3 hexagonal plates and hexagonal bipyramids were obtained for reaction with KOH and EDA, respectively. When both KOH and EDA were added into the reaction system, we observed an interesting phase transformation from α-Fe2O3 to Fe3O4 at low-temperature <span class="hlt">hydrothermal</span> conditions. The phase transformation involves the formation of α-Fe2O3 hexagonal plates, the dissolution of the α-Fe2O3 hexagonal plates, the reduction of Fe3+ to Fe2+, and the nucleation and growth of new Fe3O4 polyhedral particles. PMID:24940172</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/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/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://www.osti.gov/scitech/biblio/85441','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/85441"><span id="translatedtitle">Effluent from diffuse <span class="hlt">hydrothermal</span> venting. 1: A simple model of plumes from diffuse <span class="hlt">hydrothermal</span> sources</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Trivett, D.A.</p> <p>1994-09-01</p> <p>This paper focuses on modeling the fate of effluent from diffuse seafloor <span class="hlt">hydrothermal</span> activity after it has been vented into the water column. The model was formulated using a number of simplifying assumptions which permit direct application of this model to field measurements. I have limited the configurations to those where the <span class="hlt">hydrothermal</span> outflow velocities are smaller than horizontal current. I assume that the entrainment of ambient seawater into the plume is constant over the length of the plume. This permits formulation of a first-order relation for the rise height and dilution in a diffuse <span class="hlt">hydrothermal</span> plume as a function of downstream distance. The analytic model is compared with a simple laboratory simulation of the <span class="hlt">hydrothermal</span> flow. The results suggest that diffuse <span class="hlt">hydrothermal</span> effluent will penetrate to a height in the water column that is proportional to the overall dimension of the diffuse vent patch, multiplied by a dimensionless plume intensity parameter. I also ahow relations for plume dilution which will be compared with field data in part 2 of this work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040173290&hterms=34S%2f32S+ratios+water&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D34S%252F32S%2Bratios%2Bwater','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040173290&hterms=34S%2f32S+ratios+water&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D34S%252F32S%2Bratios%2Bwater"><span id="translatedtitle">Stable light isotope biogeochemistry of <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>Des Marais, D. J.</p> <p>1996-01-01</p> <p>The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of <span class="hlt">hydrothermal</span> systems. <span class="hlt">Hydrothermal</span> alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of <span class="hlt">hydrothermal</span> fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at <span class="hlt">hydrothermal</span> temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9243011','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9243011"><span id="translatedtitle">Stable light isotope biogeochemistry of <span class="hlt">hydrothermal</span> systems.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Des Marais, D J</p> <p>1996-01-01</p> <p>The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of <span class="hlt">hydrothermal</span> systems. <span class="hlt">Hydrothermal</span> alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of <span class="hlt">hydrothermal</span> fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at <span class="hlt">hydrothermal</span> temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2. PMID:9243011</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.ncbi.nlm.nih.gov/pubmed/25150971','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25150971"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> carbonization of poly(vinyl chloride).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poerschmann, J; Weiner, B; Woszidlo, S; Koehler, R; Kopinke, F-D</p> <p>2015-01-01</p> <p>Poly(vinyl chloride) (PVC) was subjected to <span class="hlt">hydrothermal</span> carbonization in subcritical water at 180-260 °C. Dehydrochlorination increased with increasing reaction temperature. The release of chlorine was almost quantitative above ∼235 °C. The fraction of organic carbon (OC) recovered in the hydrochar decreased with increasing operating temperature from 93% at 180 °C to 75% at 250 °C. A wide array of polycyclic aromatic hydrocarbons (PAHs) could be detected in the aqueous phase, but their combined concentration amounted to only ∼140 μg g(-1) PVC-substrate at 240 °C. A pathway for the formation of cyclic hydrocarbons and O-functionalized organics was proposed. Chlorinated hydrocarbons including chlorophenols could only be identified at trace levels (low ppb). Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) could not be detected. The sorption potential of the hydrochar turned out to be very low, in particular for polar organic pollutants. Our results provide strong evidence that <span class="hlt">hydrothermal</span> carbonization of household organic wastes which can be tied to co-discarded PVC-plastic residues is environmentally sound regarding the formation of toxic organic products. Following these findings, <span class="hlt">hydrothermal</span> treatment of PVC-waste beyond operating temperatures of ∼235 °C to allow complete release of organic chlorine should be further pursued. PMID:25150971</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('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://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="http://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://www.ncbi.nlm.nih.gov/pubmed/25867636','PUBMED'); return false;" href="http://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="http://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. PMID:25867636</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://www.osti.gov/scitech/biblio/51567','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/51567"><span id="translatedtitle">Hydroxyapatite ceramics from <span class="hlt">hydrothermally</span> prepared powders</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lin, C.H.; Huang, C.W.; Chang, S.C.</p> <p>1994-12-31</p> <p>Hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}(OH)) is an effective material for artificial human bone production. Hydroxyapatite powders were <span class="hlt">hydrothermally</span> produced in this work by reacting Ca(OH){sub 2} with Na{sub 3}PO{sub 4}{center_dot}12H{sub 2}O in an autoclave at various temperature and for various times. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50 nm, as well as independent of reaction time. The hydroxyapatite powders were compacted and sintered at various temperatures for 2 hrs. The density, grain size, and hardness of the hydroxyapatite ceramics were measured and compared with those of the hydroxyapatite ceramics produced by the powders from the commercial source. The hydroxyapatite ceramics from the <span class="hlt">hydrothermal</span> powders were found to have a higher density, smaller grain size, and higher hardness. After the hydroxyapatite ceramics were dipped in a simulated biological body liquid for 10 days, the density and hardness of the hydroxyapatite ceramics from the <span class="hlt">hydrothermal</span> powders were less deteriorated than those of the hydroxyapatite ceramics from the commercial powder.</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://adsabs.harvard.edu/abs/2012JSSCh.189...32S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSSCh.189...32S"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis map of bismuth titanates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sardar, Kripasindhu; Walton, Richard I.</p> <p>2012-05-01</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 NaBiO3·2H2O and anatase TiO2 in concentrated NaOH solution at 240 °C is shown to produce perovskite and sillenite phases Na0.5Bi0.5TiO3 and Bi12TiO20, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi1.43Ti2O6(OH)0.29(H2O)0.66 is formed. The use of a mixture of HNO3 and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi4Ti3O12. 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 LIII-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.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H51B1187B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H51B1187B"><span id="translatedtitle">Mg Isotope Fractionation During <span class="hlt">Hydrothermal</span> Ultramafic Rock Alteration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beinlich, A.; Mavromatis, V.; Austrheim, H.; Oelkers, E. H.</p> <p>2013-12-01</p> <p>Both riverine and ocean waters are enriched in 24Mg compared to the homogenous chondritic Mg isotopic composition of the Earth's mantle requiring a fractionation step that is generally attributed to low temperature continental crust weathering [1,2,3]. Here we present new observations on the Mg isotope fractionation during <span class="hlt">hydrothermal</span> alteration of ultramafic rocks from three different localities in Norway, the Linnajavri Ultramafic Complex (LUC), the Feragen Ultramafic Body (FUB), and the Solund Sedimentary Basin (SSB). Mineral separates of coexisting olivine and serpentine from serpentinized peridotite samples from the FUB and SSB exhibit invariant Mg isotope ratios suggesting that serpentinization does not fractionate Mg isotopes. In contrast, antigorite carbonation at the LUC resulted in significant inter-mineral Mg isotope fractionation among the antigorite, magnesite, and talc. The carbonation of the natural samples is constrained by O isotope thermometry at ~275 °C [4] and hence closes the temperature gap between previous investigations of the natural distribution of Mg isotopes during surface weathering and magmatic processes. Textures, mass-balance, and reaction path considerations indicate that antigorite carbonation conserved Mg and Si. The precursor antigorite has an isotopic composition of δ26Mg (DSM3)=-0.11×0.05 ‰, whereas the talc is enriched in 26Mg with mean δ26Mg=0.17×0.08 ‰ and the magnesite is depleted in 26Mg with mean δ26Mg=-0.95×0.15 ‰. This <span class="hlt">hydrothermal</span> fractionation has significant implications for the Mg isotopic compositions of natural surface waters. Our results suggest that carbonation reactions beneath off-axis low temperature <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> may exert an important control on the Mg isotope ratio in ocean water. As carbonate minerals dissolve significantly faster than silicate minerals [5,6], the chemical weathering of carbonated ultramafic and by analogy mafic rocks on the continents will yield isotopically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B21B0892W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B21B0892W"><span id="translatedtitle">Organic Acids as Hetrotrophic Energy Sources 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>Windman, T. O.; Zolotova, N.; Shock, E.</p> <p>2004-12-01</p> <p>Many thermophilic microbes are heterotrophs, but little is known about the organic compounds present in <span class="hlt">hydrothermal</span> ecosystems. More is known about what these organisms will metabolize in lab experiments than what they do metabolize in nature. In an effort to bridge this gap, we have begun to incorporate organic analyses into ongoing research on Yellowstone <span class="hlt">hydrothermal</span> ecosystems. After filtering at least a liter of hot spring water to minimize contamination, samples were collected into sixty-milliliter serum vials containing ultra-pure phosphoric acid, sodium hydroxide, or benzalkonium chloride. Approximately 80 <span class="hlt">sites</span> were sampled spanning temperatures from 60 to 90°C and pH values from 2 to 9. Analytical data for organic acid anions (including formate, acetate, lactate, and succinate) were obtained by ion chromatography. Preliminary results indicate that concentrations of organic acids anions range from 5 to 300 ppb. These results can be used with other field and lab data (sulfate, sulfide, nitrate, ammonia, bicarbonate, pH, hydrogen) in thermodynamic calculations to evaluate the amounts of energy available in heterotrophic reactions. Preliminary results of such calculations show that sulfate reduction to sulfide coupled to succinate oxidation to bicarbonate yields about 6 kcal per mole of electrons transferred. When formate oxidation to bicarbonate or hydrogen oxidation to water is coupled to sulfate reduction there is less energy available by approximately a factor of two. A comparison with nitrate reduction to ammonia involving succinate and/or formate oxidation reveals several similarities. Using formate to reduce nitrate can yield about as much energy as nitrate reduction with hydrogen (typically 12 to 14 kcal per mole of electrons transferred), but using succinate can yield more than twice as much energy. In fact, reduction of nitrate with succinate can provide more energy than any of the inorganic nitrate reduction reactions involving sulfur, iron</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.V53D..07R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.V53D..07R"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Plume Geochemistry along the East Lau Spreading Center</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. A.; Baker, E.; Martinez, F.; Buck, N.; Walker, S.; Seewald, J.; Proskurowski, G.; Lupton, J.; Wheat, G.</p> <p>2008-12-01</p> <p>In 2004 and 2008, we conducted extensive surveys of <span class="hlt">hydrothermal</span> plumes along the East Lau Spreading Center (ELSC) in the Lau Back Arc Basin. The survey in 2008 is the most comprehensive plume survey conducted on any ridge to date. It covered 100 km2 by towing the 120 kHz side scan sonar and associated sensors from 19.9 to 21° S at 1 km intervals extending 5km on each side of the ridge crest. This part of the survey encompassed the known vent fields, Tow Cam, ABE, and Kila Moana. A fourth major vent field north of ABE was also identified. Near the ABE vent field survey lines were done at 0.5km intervals. The Valu Fa Ridge from 21.9 to 22.4°S was also surveyed using 7 lines at 0.7km spacing. The side scan sonar was towed ~ 100m above the sea floor with plume sensing instruments on the towline, clump weight, sonar, and on a line extended below the clump weight. Plume sensors included the Vents In Situ Analyzer, optical backscatter, Oxidation Reduction Potential, and CTD. Vertical and towed hydrocasts were located in areas of interest to collect sea water samples for chemical characterization of the plumes. While the surveys indicate that robust (high temperature) venting was restricted to an area within 1km of the ridge axis, there was some limited evidence of lower temperature venting further form the axis. The plume data from the sensors and discrete samples will be used to chemically characterize the <span class="hlt">hydrothermal</span> plumes found along the ELSC. Emphasis will be placed on known vent fields and the North ABE field. 3He and Mn in the plumes will be compared to vent fluid data at the known <span class="hlt">sites</span>. Although the N. ABE field appears to be the largest of the vent fields in this region, vent fluids from it have not yet been collected. The plumes above N. ABE have the most elevated levels of 3He and Mn of all of the plumes sampled along the ELSC and Valu Fa Ridges. This vent field is located closer to the transitions between andesitic rocks in the south and basaltic rocks in</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('http://www.ncbi.nlm.nih.gov/pubmed/25108489','PUBMED'); return false;" href="http://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="http://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. PMID:25108489</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210070Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210070Z"><span id="translatedtitle">Taal volcanic <span class="hlt">hydrothermal</span> system (Philippines) inferred by electromagnetic and other geophysical methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zlotnicki, Jacques; Toutain, Jean Paul; Sasai, Yoichi; Villacorte, Egardo; Bernard, Alain; Fauquet, Frederic; Nagao, Toshiyatsu</p> <p>2010-05-01</p> <p>On volcanoes which display <span class="hlt">hydrothermal</span>/magmatic unrests, Electromagnetic (EM) methods can be combined with geochemical (GC) and thermal methods. The integration of these methods allows to image in detail <span class="hlt">hydrothermal</span> systems, to find out possible scenarios of volcanic unrest, and to monitor the on-going activity with knowledge on the sources of heat, gas and fluid transfers. Since the 1990's the volcano shows recurrent periods of seismic activity, ground deformation, <span class="hlt">hydrothermal</span> activity, and surface activity (geysers). Combined EM and GC methods noticeably contribute to map in detail the <span class="hlt">hydrothermal</span> system and to analyse the sources of the activity: - Total magnetic field mapping evidences demagnetised zones over the two main areas forming the <span class="hlt">hydrothermal</span> system (in the northern part of Main crater (MC)). These low magnetized areas are ascribed to thermal sources located at some hundreds metres of depth, - Self-potential surveys, delineate the contours of the fluids-heat transfer, and the northern and southern structural discontinuities enclosing the <span class="hlt">hydrothermal</span> system, - Ground temperature gradient measurements evidence the distinctive heat transfer modes, from low fluxes related to soil temperature dominated by solar input to extremely high temperature gradients of 1200 °C m-1 or to more related to magmatic fluids. - Ground temperature and surface temperature of central acidic lake calculated by Thermal Aster imaging highlight the location of the most active ground fissures, outcrops and diffuse areas. Higher and larger anomalies are observed in the northern part of MC. A rough estimation of the thermal discharge in the northern part of the volcano gives 17 MW. - CO2 concentrations and fluxes from soil supply inform on fluids origin and on local processes operating along active fractures. Much higher carbon dioxide fluxes at MC <span class="hlt">sites</span> confirm that the source of Taal activity is presently located in the northern part of the crater. - Heat and fluids release</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..1616710Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..1616710Y&link_type=ABSTRACT"><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/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/cgi-bin/nph-data_query?bibcode=2016JVGR..314..142W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JVGR..314..142W&link_type=ABSTRACT"><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/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.1124T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.1124T&link_type=ABSTRACT"><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://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/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://adsabs.harvard.edu/abs/2006AGUFM.B31B1093L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B31B1093L"><span id="translatedtitle">U and Th Concentration and Isotopic Composition of <span class="hlt">Hydrothermal</span> Fluids at 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>Ludwig, K. A.; Shen, C.; Cheng, H.; Edwards, R.; Kelley, D. S.; Butterfield, D. A.</p> <p>2006-12-01</p> <p>Uranium and Th concentration and isotopic composition of <span class="hlt">hydrothermal</span> fluids at the Lost City <span class="hlt">Hydrothermal</span> Field (LCHF) were determined using multi-collector inductively coupled plasma mass spectrometry (MC-ICP- MS). The LCHF is an off-axis, serpentinite-hosted <span class="hlt">hydrothermal</span> system located at 30°N near the Mid- Atlantic Ridge. Carbonate chimneys reaching 60 m in height vent alkaline (pH~10), calcium-rich fluids at 40- 91°C and the towers are home to dense microbial communities. Vent fluid and seawater U and Th concentration and isotopic composition data provide critical information for constraining U-Th chimney ages. The increased sensitivity (1-2%) of MC-ICP-MS combined with an Aridus nebulization system allows the precise measurement of small quantities of sample (~150 ml) with low concentrations (<<1ng/g) of U and Th. In this study, we have developed MC-ICP-MS techniques to measure the U and Th concentration and isotopic composition (234U, 238U, 230Th, and 232Th) of eight <span class="hlt">hydrothermal</span> fluid samples. Endmember fluids with ~1mmol/kg Mg have ~0.02 ng/g U, confirming that end-member fluids contain near-zero values of both Mg and U. Thorium concentrations of fluids are close to deep seawater values. U and Th isotopic compositions are reported at the permil level. These data may provide new insights into the role of serpentinite-hosted <span class="hlt">hydrothermal</span> systems in the budgets of U and Th in the ocean. Techniques presented in this study may be applied to other <span class="hlt">hydrothermal</span> and seep environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MatSP..31...52T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MatSP..31...52T"><span id="translatedtitle">Extraction of edingtonite from a natural zeolite under <span class="hlt">hydrothermal</span> conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tutti, F.; Kamyab, S. M.; Barghi, M. A.; Badiei, A.</p> <p>2013-01-01</p> <p>In the present study, edingtonite has been extracted from natural zeolite clinoptilolite by simulating the natural <span class="hlt">hydrothermal</span> conditions in the laboratory, under the influence of solutions with different concentrations of Ba+2 and Na+, varying from 0.5 to 2.8 mol/L, at 150 °C. In this work, the essential <span class="hlt">hydrothermal</span> conditions have been provided by <span class="hlt">hydrothermal</span> autoclaves. The natural and laboratory prepared samples were characterized by XRD, XRF and SEM methods.</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="http://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> </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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4406493','PMC'); return false;" href="http://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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.B13A0164P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.B13A0164P&link_type=ABSTRACT"><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://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://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=crystalline+silica&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dcrystalline%2Bsilica','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830034360&hterms=crystalline+silica&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dcrystalline%2Bsilica"><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/cgi-bin/nph-data_query?bibcode=2010AGUFMOS11D..06G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMOS11D..06G&link_type=ABSTRACT"><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/2011AGUFMOS11B1488T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMOS11B1488T"><span id="translatedtitle">First <span class="hlt">hydrothermal</span> active vent discovered on the Galapagos Microplate</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.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party</p> <p>2011-12-01</p> <p>The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and <span class="hlt">hydrothermal</span> vent community were firstly confirmed on the GSC. Lots of <span class="hlt">hydrothermal</span> fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new <span class="hlt">hydrothermal</span> fields were confirmed. One is named 'Precious Stone Mountain', which is the first <span class="hlt">hydrothermal</span> field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' <span class="hlt">hydrothermal</span> field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. <span class="hlt">Hydrothermal</span> fluids emitting from the fissures and <span class="hlt">hydrothermal</span> fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. <span class="hlt">Hydrothermal</span> fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' <span class="hlt">hydrothermal</span> field. The result indicates that seafloor materials around the <span class="hlt">hydrothermal</span> field can be characterized into three types, such as the fresh lava, <span class="hlt">hydrothermal</span> sediment, and altered rock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22348625','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22348625"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> synthesis of hexagonal magnesium hydroxide nanoflakes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, Qiang; Li, Chunhong; Guo, Ming; Sun, Lingna; Hu, Changwen</p> <p>2014-03-01</p> <p>Graphical abstract: Hexagonal Mg(OH){sub 2} nanoflakes were synthesized via <span class="hlt">hydrothermal</span> method in the presence of PEG-20,000. Results show that PEG-20,000 plays an important role in the formation of this kind of nanostructure. The SAED patterns taken from the different positions on a single hexagonal Mg(OH){sub 2} nanoflake yielded different crystalline structures. The structure of the nanoflakes are polycrystalline and the probable formation mechanism of Mg(OH){sub 2} nanoflakes is discussed. - Highlights: • Hexagonal Mg(OH){sub 2} nanoflakes were synthesized via <span class="hlt">hydrothermal</span> method. • PEG-20,000 plays an important role in the formation of hexagonal nanostructure. • Mg(OH){sub 2} nanoflakes show different crystalline structures at different positions. • The probable formation mechanism of hexagonal Mg(OH){sub 2} nanoflakes was reported. - Abstract: Hexagonal magnesium hydroxide (Mg(OH){sub 2}) nanoflakes were successfully synthesized via <span class="hlt">hydrothermal</span> method in the presence of the surfactant polyethylene glycol 20,000 (PEG-20,000). Results show that PEG-20,000 plays an important role in the formation of this kind of nanostructure. The composition, morphologies and structure of the Mg(OH){sub 2} nanoflakes were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The SAED patterns taken from the different positions on a single hexagonal Mg(OH){sub 2} nanoflake show different crystalline structures. The structure of the nanoflakes are polycrystalline and the probable formation mechanism of Mg(OH){sub 2} nanoflakes is discussed. Brunauer–Emmett–Teller (BET) analysis were performed to investigate the porous structure and surface area of the as-obtained nanoflakes.</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://adsabs.harvard.edu/abs/2004AGUFM.B13A0213S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B13A0213S"><span id="translatedtitle">Abiotic Organic Chemistry 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>Simoneit, B. R.; Rushdi, A. I.</p> <p>2004-12-01</p> <p>Abiotic organic chemistry in <span class="hlt">hydrothermal</span> systems is of interest to biologists, geochemists and oceanographers. This chemistry consists of thermal alteration of organic matter and minor prebiotic synthesis of organic compounds. Thermal alteration has been extensively documented to yield petroleum and heavy bitumen products from contemporary organic detritus. Carbon dioxide, carbon monoxide, ammonia and sulfur species have been used as precursors in prebiotic synthesis experiments to organic compounds. These inorganic species are common components of hot spring gases and marine <span class="hlt">hydrothermal</span> systems. It is of interest to further test their reactivities in reductive aqueous thermolysis. We have synthesized organic compounds (lipids) in aqueous solutions of oxalic acid, and with carbon disulfide or ammonium bicarbonate at temperatures from 175-400° C. The synthetic lipids from oxalic acid solutions consisted of n-alkanols, n-alkanoic acids, n-alkyl formates, n-alkanones, n-alkenes and n-alkanes, typically to C30 with no carbon number preferences. The products from CS2 in acidic aqueous solutions yielded cyclic thioalkanes, alkyl polysulfides, and thioesters with other numerous minor compounds. The synthesis products from oxalic acid and ammonium bicarbonate solutions were homologous series of n-alkyl amides, n-alkyl amines, n-alkanes and n-alkanoic acids, also to C30 with no carbon number predominance. Condensation (dehydration) reactions also occur under elevated temperatures in aqueous medium as tested by model reactions to form amide, ester and nitrile bonds. It is concluded that the abiotic formation of aliphatic lipids, condensation products (amides, esters, nitriles, and CS2 derivatives (alkyl polysulfides, cyclic polysulfides) is possible under <span class="hlt">hydrothermal</span> conditions and warrants further studies.</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://adsabs.harvard.edu/abs/2014AGUFM.H33B0803T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H33B0803T"><span id="translatedtitle">Porosity evolution in Icelandic <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>Thien, B.; Kosakowski, G.; Kulik, D. A.</p> <p>2014-12-01</p> <p>Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced <span class="hlt">hydrothermal</span> systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems, grant number CRSII2_141843/1) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. These are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. These shallow plutons increase the geothermal gradient and trigger the circulation of <span class="hlt">hydrothermal</span> waters with a steam cap forming at shallow depth. Field observations suggest that active and fossil Icelandic <span class="hlt">hydrothermal</span> systems are built from a superposition of completely altered and completely unaltered layers. With help of 1D and 2D reactive transport models (OpenGeoSys-GEM code), we investigate the reasons for this finding, by studying the mineralogical evolution of protoliths with different initial porosities at different temperatures and pressures, different leaching water composition and gas content, and different porosity geometries (i.e. porous medium versus fractured medium). From this study, we believe that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are key factors to explain the different alteration extents observed in field studies. We also discuss how precipitation and dissolution kinetics can influence the alteration time scales.</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/2012AGUFMOS13A1706T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13A1706T"><span id="translatedtitle">U-Th and ESR dating of drilled cores from a giant <span class="hlt">hydrothermal</span> mounds in South Mariana</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takamasa, A.; Nakai, S.; Sato, F.; Toyoda, S.; Ishibashi, J.</p> <p>2012-12-01</p> <p>The time scale for <span class="hlt">hydrothermal</span> activity is an important factor controlling the size of <span class="hlt">hydrothermal</span> ore deposits and the evolution of chemosynthesis-based communities in a submarine <span class="hlt">hydrothermal</span> system. We determined the age of <span class="hlt">hydrothermal</span> deposits samples, both collected samples by submersible and drilled core samples from South Mariana Trough. Samples were collected from four <span class="hlt">hydrothermal</span> <span class="hlt">sites</span>, Snail (near the spreading axis), Archean ( 1.5km from the axis), Pika ( 4.9km from the axis) and Urashima ( 4.9km from the axis). 230Th-234U radioactive disequilibrium dating was applied to <span class="hlt">hydrothermal</span> sufide minerals consisting of pyrite and sphalerite while electron spin resonance (ESR) dating was applied to barite. For 230Th-234U radioactive disequilibrium dating, we carried out magnetic separation for bulk samples, then we digested samples with nitric acid. U and Th were purified by two-step column separations, and isotopic compositions of spiked and unspiked U and Th were measured by a MC-ICP-MS. Analytical methods for ESR age determination were described in a companion abstract by Toyoda et al. We found that the magnetic fractions had significantly higher U/Th ratios, which enabled 230Th-234U age determinations as precise as ±2% (2σ). This probably reflects that pyrite enriched in magnetic fractions has high U/Th ration. In a sulfide crust sample collected from Archean <span class="hlt">site</span>, the 230Th-234U ages of the sulfide minerals (0.3-2.2 ka) were compared with ESR ages of barites separated from 12 subsamples of the same sulfide crust. ESR ages (0.27 - 1.7 ka) show a spatial pattern broadly resembling that observed in 230Th-234U dating method. While there are some significant offsets, these results illustrate the potential of the two methods for use in provide information on evolution history of a <span class="hlt">hydrothermal</span> system. Samples from Pika, Archean and Snail <span class="hlt">sites</span> yield from 0.5 to ~9 ka, from 0.1 to 3 ka and < ~90 a, respectively. The oldest ages from each <span class="hlt">site</span> are correlated</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/12004120','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/12004120"><span id="translatedtitle">Merging genomes with geochemistry in <span class="hlt">hydrothermal</span> ecosystems.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reysenbach, Anna-Louise; Shock, Everett</p> <p>2002-05-10</p> <p>Thermophilic microbial inhabitants of active seafloor and continental hot springs populate the deepest branches of the universal phylogenetic tree, making <span class="hlt">hydrothermal</span> ecosystems the most ancient continuously inhabited ecosystems on Earth. Geochemical consequences of hot water-rock interactions render these environments habitable and supply a diverse array of energy sources. Clues to the strategies for how life thrives in these dynamic ecosystems are beginning to be elucidated through a confluence of biogeochemistry, microbiology, ecology, molecular biology, and genomics. These efforts have the potential to reveal how ecosystems originate, the extent of the subsurface biosphere, and the driving forces of evolution. PMID:12004120</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> </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('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/2010AGUFM.T13B2187R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T13B2187R"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> Activity and its Chemical Characteristics in the NE Lau Basin</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. A.; Lilley, M. D.; Baker, E. T.; Lupton, J. E.; Embley, R. W.; Buck, N.; Walker, S. L.; Olson, E. J.; Dziak, R. P.; Baumberger, T.</p> <p>2010-12-01</p> <p>The NE Lau Basin is a magmatically robust area with an abundance of <span class="hlt">hydrothermal</span> activity. We conducted exploratory research to the NE Lau Basin during three cruises to the area in November 2008, May 2009, and May 2010. We have found an unusual density of <span class="hlt">hydrothermal</span> activity in the area bounded by the NE Lau Spreading Center (NELSC) and the Tongan Magmatic arc. Aside from the magmatic activity at the NELSC and the Tonga Arc, this area includes a area of crustal extension, where nine elongate volcanoes (The Matas) lie in a 25km arc extending into the Tonga trench with the summits from ˜1200m to ˜ 2700m depth and a large volcanic feature (Volcano “O”) which is characterized by a caldera >10km diameter with an emergent dome in its SE quadrant. Finally, the basin bounded by the Matas, the NELSC, and Volcano “O” contain many large lava flows with elevated acoustic backscatter suggesting a relatively young age. During the cruise in 2008, two ongoing eruptions were encountered in the region, one at the NELSC and another at W Mata volcano. These eruptions were later confirmed using the Jason II submersible in 2009. W Mata has been continuously erupting over the course of our observations. In addition to the eruption on the NELSC, <span class="hlt">hydrothermal</span> activity was also observed at Maka and Tafu volcanoes, which are south and north of the eruptive area respectively. Observations of <span class="hlt">hydrothermal</span> activity at two <span class="hlt">sites</span> were made within the caldera at Volcano “O” and on the volcanic arc at two depths on Niua Volcano. The cruise in May 2010, revealed dense <span class="hlt">hydrothermal</span> activity along the Mata chain where eight of the nine Mata volcanoes were <span class="hlt">hydrothermally</span> active, including W Mata. <span class="hlt">Hydrothermal</span> activity in this region is very sulfur rich as documented by large amounts of elemental sulfur at “O”, Niua, and seven of the Matas (elemental sulfur is inferred from light scatter and particulate matter color; analyses are pending), by acidic magmatic volatiles at”O” and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T23F2661B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T23F2661B"><span id="translatedtitle">Two <span class="hlt">hydrothermal</span> fields at the southern Central Indian Ridge (CIR) - structural and magnetic investigations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bartsch, C.; Barckhausen, U.</p> <p>2013-12-01</p> <p>With the research cruises INDEX in the years 2011 and 2012 we investigated the active ridge system of the southern Central Indian Ridge (CIR) in the Indian Ocean at the Rodriguez Triple Junction (RTJ) in terms of <span class="hlt">hydrothermal</span> activities. Based on the analysis of structural/bathymetric and magnetic data we found indicators for the activity of <span class="hlt">hydrothermal</span> vent <span class="hlt">sites</span> which are related to the geometry of the ridge and the magma chambers. The CIR represents a typical slow spreading rift axis which strikes approximately north-south with an average spreading rate of 4.7 cm/a. An analysis of the spreading velocities from NW to SE illustrates a slight decrease from 4.7 cm/a to 4.5 cm/a at the RTJ. From 21°S to 25°30'S the ridge consists of six sections separated by discontinuities and one transform fault. The rift valley shows an asymmetric behaviour with steep slopes in the east and shallower slopes in the western part. The position of the center of magnetic Anomaly 1 is in some cases influenced by structural features like an overlapping spreading center and bending, along axis updoming, and an oceanic core complex. Furthermore, the spreading velocities show local changes near prominent structural features like the Knorr seamount. In this particular case, recent spreading was almost entirely confined to the western flank of the CIR. While the Knorr seamount blocks spreading in eastern direction. In general, in the mapped area a discrepancy between the center of magnetic Anomaly 1 and the bathymetric expression of the spreading center can be noticed in many places. In the northwestern part of the working area the active spreading axis lies west of the center of magnetic Anomaly 1, whereas in the southeastern part indications for a recent ridge jump to the east are observed. Such tectonic activities in combination with magmatic events are indicators for <span class="hlt">hydrothermal</span> activity. In terms of structural geology normal faults and detachment faults represent pathways for the</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://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/cgi-bin/nph-data_query?bibcode=2015AGUFMOS43A2033H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMOS43A2033H&link_type=ABSTRACT"><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.B13B0475S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B13B0475S"><span id="translatedtitle">Bacterial and Archaeal Community Dynamics at CO2-RICH Shallow-Sea <span class="hlt">Hydrothermal</span> Vents (panarea, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schubotz, F.; Huang, C.; Meyerdierks, A.; Amend, J.; Price, R. E.; Amann, R.; Hinrichs, K.; Summons, R. E.</p> <p>2013-12-01</p> <p>Shallow marine <span class="hlt">hydrothermal</span> vents are highly dynamic systems with unique habitats that can support both chemosynthetic and photosynthetic communities at steep temperature and geochemical gradients. Here, we present a combined organic geochemical and microbiological approach to describe the microbial community composition and their metabolism at the CO2-rich shallow <span class="hlt">hydrothermal</span> vents off Panarea Island, in Sicily. We investigated two contrasting <span class="hlt">hydrothermal</span> environments: Hot Lake, a depression filled with <span class="hlt">hydrothermal</span> fluids diffusing gradually out of the seafloor, with temperatures ranging from 40 to 70°C, and Blackpoint, a <span class="hlt">site</span> with vigorous venting of <span class="hlt">hydrothermal</span> gasses and fluids with temperatures as high as 135°C. At Hot Lake, Bacteria dominate the microbial community composition in the sediments. 16S rRNA clone libraries revealed Bacteriodetes-, Epsilonproteobacteria- and Deltaproteobacteria-related sequences as the most abundant members. Bacterial intact polar membrane lipids (IPLs) were dominated by the non-phosphorous containing ornithine lipids throughout all depths, indicating an important role of this aminolipid at elevated temperatures and/or low pH. At Hot Lake, archaeal IPLs were comprised mainly of glycosidic tetraethers and increased up to 20% of total IPLs with increasing temperature and depth. At the same <span class="hlt">site</span>, archaeal 16S rRNA clone libraries were mainly comprised of Euryarchaea-affiliated sequences; crenarchaeotal sequences were only found in deeper sediment layers with temperatures of ca. 70°C. In contrast to Hot Lake, Archaea dominated sediments at the much hotter <span class="hlt">site</span> at Blackpoint. Here, novel methylated H-shaped archaeal tetraethers, with multiple sugars as head groups, were the most abundant membrane lipids. Reports on these lipids in cultures are very limited, but their abundant occurrence at elevated temperatures suggests an important role in membrane homeostastis in thermophilic Archaea. Stable carbon isotope values of -35‰ to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040173291&hterms=history+microbiology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dhistory%2Bmicrobiology','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040173291&hterms=history+microbiology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dhistory%2Bmicrobiology"><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://adsabs.harvard.edu/abs/2002AGUFM.V72A1282O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V72A1282O"><span id="translatedtitle">Euryhaline Halophilic Microorganisms From the Suiyo Seamount <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>Okamoto, T.; Kimura, H.; Maruyama, A.; Naganuma, T.</p> <p>2002-12-01</p> <p>The euryhaline halophilic microorganisms grow in a wide salinity range from <3% NaCl (seawater equivalent) to >15% NaCl or to even saturation (about 30% NaCl). A number of euryhaline halophiles have been found in a wide range of habitats from oceanic and terrestrial regimes, from deep-sea vents and seeps, and from Antarctic sea ice and terrains. We have isolated the euryhaline strains independently from a Mid-Atlantic Ridge vent fluids and Antarctic terrains are closely related species of the genus Halomonas. Some euryhaline halophiles maintain intracellular osmotic balance by controlling the concentration of compatible solute such as ectoine. This compatible solute not only stabilizes the proteins from denaturation caused by high salt concentration but also serves as a protectant against stresses such as heating, freezing and drying. The sub-seafloor structure of a <span class="hlt">hydrothermal</span> vent is highly complicated with mosaic heterogeneity of physicochemical parameters such as temperature and salinity. This premise led us to the hypothesis that some euryhaline halophiles including Halomonas species well adapt to a wide salinity-ranged habitat in the sub-vent. To test this hypothesis, isolation and characterization of euryhaline halophiles from the Suiyo Seamount <span class="hlt">hydrothermal</span> vents were conducted the drill-cored rock samples from the <span class="hlt">sites</span> APSK-02, 03, and 07 and the filter-trapped fluid particle samples from the <span class="hlt">sites</span> APSK-01 and 05 were used. For initial cultivation, a heterotrophic bacterial medium of 15% NaCl was used. The samples was added to the medium and incubated under both aerobic and anaerobic conditions at room temperature. A total of 5 euryhaline halophilic strains were obtained and phylogenetically characterized: two strains (both related to Marinobacter) from APSK-02 core section 2; one strain (related to H. meridiana) from APSK-07 core section 3; and two strains (related to H. meridiana and H. variabilis) from APSK-01 trapped particles. In addition, some</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/2015JVGR..303...16L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JVGR..303...16L"><span id="translatedtitle">Integrated thermal infrared imaging and structure-from-motion photogrammetry 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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lewis, A.; Hilley, G. E.; Lewicki, J. L.</p> <p>2015-09-01</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 °C 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://pubs.er.usgs.gov/publication/70157314','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157314"><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://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('http://www.ncbi.nlm.nih.gov/pubmed/24709539','PUBMED'); return false;" href="http://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="http://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. PMID:24709539</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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3751430','PMC'); return false;" href="http://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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/375912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/375912"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> reactions 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>1995-12-31</p> <p>The emphasis of the work done has been to determine the reactivities of two ashes believed to be representative of those generated. A bituminous ash and a lignitic ash have been investigated. The reactions of these ashes undergo when subjected to mild <span class="hlt">hydrothermal</span> conditions were explored. The nature of the reactions which the ashes undergo when alkaline activators, calcium hydroxide and calcium sulfate are present was also investigated. It was determined that calcium silicate hydrate, calcium aluminate hydrate, and the calcium sulfoaluminate hydrate ettringite form under these conditions. It appears 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSO{sub 4}{center_dot}32H{sub 2}O (ettringite) formation needs to be considered in ashes which contain significant amounts of sulfate. Therefore the stability region for ettringite was established. It was also determined that calcium silicate hydrate, exhibiting a high internal surface area, will readily form with <span class="hlt">hydrothermal</span> treatment between 50{degrees} and 100{degrees}C. This phase is likely to have a significant capacity to take up heavy metals and oxyanions and this ability is being explored.</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://www.osti.gov/scitech/biblio/6874777','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6874777"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> system at Newberry Volcano, Oregon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sammel, E.A.; Ingebritsen, S.E.; Mariner, R.H.</p> <p>1988-09-10</p> <p>Results of recent geological and geophysical studies at Newberry Volcano have been incorporated into conceptual and numerical models of a magma-based <span class="hlt">hydrothermal</span> system. Numerical simulations begin with emplacement of a small magma body, the presumed source of silicic eruptions at Newberry that began about 10,000 B.P., into a thermal regime representing 100,000 years of cooling of a large underlying intrusion. Simulated flow patterns and thermal histories for three sets of hypothetical permeability values are compatible with data from four geothermal drill holes on the volcano. Meteoric recharge cools the caldera-fill deposits, but thermal water moving up a central conduit representing a permeable volcanic vent produces temperatures close to those observed in drill holes within the caldera. Meteoric recharge from the caldera moves down the flanks and creates a near-isothermal zone that extends several hundred meters below the water table, producing temperature profiles similar to those observed in drill holes on the flanks. The temperatures observed in drill holes on the flanks are not influenced by the postulated Holocene magma body. The elevated temperature gradients measured in the lower portions of these holes may be related to the cumulative effect of older intrusions. The models also indicate that meteoric recharge to the deep <span class="hlt">hydrothermal</span> system probably originates within or near the caldera. Relatively low fluid velocities at depth suggest that at least a significant fraction of the thermal fluid may be very old.</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('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="http://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="http://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://www.ncbi.nlm.nih.gov/pubmed/20975681','PUBMED'); return false;" href="http://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="http://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>2010-01-01</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. PMID:20975681</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="http://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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20099811','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20099811"><span id="translatedtitle">Deep-sea <span class="hlt">hydrothermal</span> vents: potential hot spots for natural products discovery?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thornburg, Christopher C; Zabriskie, T Mark; McPhail, Kerry L</p> <p>2010-03-26</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents are among the most extreme and dynamic environments on Earth. However, islands of highly dense and biologically diverse communities exist in the immediate vicinity of <span class="hlt">hydrothermal</span> vent flows, in stark contrast to the surrounding bare seafloor. These communities comprise organisms with distinct metabolisms based on chemosynthesis and growth rates comparable to those from shallow water tropical environments, which have been rich sources of biologically active natural products. The geological setting and geochemical nature of deep-sea vents that impact the biogeography of vent organisms, chemosynthesis, and the known biological and metabolic diversity of Eukarya, Bacteria, and Archaea, including the handful of natural products isolated to date from deep-sea vent organisms, are considered here in an assessment of deep-sea <span class="hlt">hydrothermal</span> vents as potential hot spots for natural products investigations. Of critical importance too are the logistics of collecting deep vent organisms, opportunities for re-collection considering the stability and longevity of vent <span class="hlt">sites</span>, and the ability to culture natural product-producing deep vent organisms in the laboratory. New cost-effective technologies in deep-sea research and more advanced molecular techniques aimed at screening a more inclusive genetic assembly are poised to accelerate natural product discoveries from these microbial diversity hot spots. PMID:20099811</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('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="http://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/19362761','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19362761"><span id="translatedtitle">High levels of natural radioactivity in biota from deep-sea <span class="hlt">hydrothermal</span> vents: a preliminary communication.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Charmasson, Sabine; Sarradin, Pierre-Marie; Le Faouder, Antoine; Agarande, Michèle; Loyen, Jeanne; Desbruyères, Daniel</p> <p>2009-06-01</p> <p><span class="hlt">Hydrothermal</span> deep-sea vent fauna is naturally exposed to a peculiar environment enriched in potentially toxic species such as sulphides, heavy metals and natural radionuclides. It is now well established that some of the organisms present in such an environment accumulate metals during their lifespan. Though only few radionuclide measurements are available, it seems likely that <span class="hlt">hydrothermal</span> vent communities are exposed to high natural radiation doses. Various archived biological samples collected on the East Pacific Rise and the Mid-Atlantic Ridge in 1996, 2001 and 2002 were analysed by ICP-MS in order to determine their uranium contents ((238)U, (235)U and (234)U). In addition (210)Po-Pb were determined in 2 samples collected in 2002. Vent organisms are characterized by high U, and Po-Pb levels compared to what is generally encountered in organisms from outside <span class="hlt">hydrothermal</span> vent ecosystems. Though the number of data is low, the results reveal various trends in relation to the <span class="hlt">site</span>, the location within the mixing zone and/or the organisms' trophic regime. PMID:19362761</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://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('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4613831','PMC'); return false;" href="http://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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015SciDr..20...51J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015SciDr..20...51J&link_type=ABSTRACT"><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://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://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="http://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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4757712','PMC'); return false;" href="http://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="http://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/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('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> </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/cgi-bin/nph-data_query?bibcode=2014AGUFMOS53C1058H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMOS53C1058H&link_type=ABSTRACT"><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://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/cgi-bin/nph-data_query?bibcode=2012AGUFM.V52A..01S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFM.V52A..01S&link_type=ABSTRACT"><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/abs/2009EGUGA..11.5563I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.5563I"><span id="translatedtitle">Feedbacks of Rock Hydration on <span class="hlt">Hydrothermal</span> Convection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iyer, K.; Ruepke, L.</p> <p>2009-04-01</p> <p>Hydration of the oceanic lithosphere is an important process which alters both the chemical and physical properties of the affected lithologies. Although <span class="hlt">hydrothermal</span> convection has been extensively researched, little work has been done on the effects of hydration reactions occurring during convection. One of the most important reactions occurring in the oceanic lithosphere is serpentinization of ultramafic rocks. We present a numerical solution for <span class="hlt">hydrothermal</span> circulation which explores the feedbacks generated during serpentinization of mantle rocks. The model is two dimensional and uses the FEM approach. Three coupled, time-dependent equations are solved: the first equation is mass conserving and is based on Darcy flow. The second equation describes heat transport and accounts for advective and diffusive heat transfer as well as latent heat effects. The final equation describes the serpentinization rate of olivine in ultramafic rocks (Emmanuel and Berkowitz, 2006) and is derived from experimental results (Martin and Fyfe, 1970). Serpentinization is a fluid-consuming process and manifests itself as a sink term in the Darcy flow equation. The exothermic heat of reaction is added as a source term in the heat transport equation. Moreover, serpentinization is associated with a large positive volume change. This large volume change may decrease the porosity of the rock but can also increase permeability by deformation. The rate of serpentinization used in the model is, therefore, also coupled to the porosity and permeability. We investigate the role of hydration in a box model using thermodynamically constrained fluid properties where the lower part is composed of reactive mantle rocks. The effects of serpentinization on the temperatures of the venting fluids and variations in flow pathways are explored. Furthermore, the model is also used in a mid-ocean ridge setting and the amount and depth of serpentinization, in addition to the above mentioned effects, is also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817495B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817495B"><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/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://www.osti.gov/scitech/biblio/6342991','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6342991"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> activity in the Lau back arc basin: Plumes and hot fluids chemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Charlou, J.L.; Donval, J.P.; Caprais, M.P.; Fouquet, Y. ); Erzinger, J. ); Von Stackelberg, U. )</p> <p>1990-06-01</p> <p>During the French-German cruise Nautile(April-May 1989), 22 dives have been completed to understand the processes of seafloor arc formation associated with <span class="hlt">hydrothermal</span> circulation along the volcanic Valu FA ridge. The CTD recordings, obtained in real time inside the Nautile, show the narrow relation between the geological structure and the temperature anomalies. The anomalies' amplitude and intensity permit the precise localization of hot <span class="hlt">hydrothermal</span> discharges (Vai Lili <span class="hlt">site</span>), diffuse (Hine Hina field) and nonperceptible inputs. Buoyant plumes producing entrainment and vertical transport up to 200 m above the seafloor are clearly identified with high CH{sub 4} (up to 4.4 {mu}l/L) and Mn (up to 90 {mu}mol/Kg) concentrations. For the first time, black smokers (240{degree} to 334{degree}C) were collected in a back arc environment. The samples (more than 90% pure <span class="hlt">hydrothermal</span> fluid) have end member pH (1.8), among the lowest ever measured in oceanic <span class="hlt">hydrothermal</span> fluids. The calculated end-member concentrations are enriched for Cl(0.65-0.75 mol/kg), Na (0.52-0.58 mol/Kg), Ca (30 mmol/Kg), K (55-67 mmol/Kg), Sr (123 {mu}mol/Kg), Rb (72-92 {mu}mol/kg), Li (690 {mu}mol/Kg). Compared with other <span class="hlt">hydrothermal</span> waters, Si is slightly depleted (12-14 mmol/Kg), Fe (1.12.5 mmol/Kg), Mn (5.8-6.9 mmol/Kg), Cu (16-43 {mu}mol/Kg), Zn (1.2- 3 mmol/Kg) concentrations are high. The Vai Lili <span class="hlt">site</span> fluid concentrations in B (twice seawater), Ba (up to 40 {mu}mol/Kg), Zn (up to 3 mmol/Kg), Pb (up to 7 {mu}mol/kg). As (up to 11 {mu}mol/Kg) as well as the molar Cs/Rb and Fe/Mn ratios of respectively 0.024 and 0.2 are unexpected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.140...20C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140...20C"><span id="translatedtitle">Rare earth elements as indicators of <span class="hlt">hydrothermal</span> processes within the East Scotia subduction zone system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cole, Catherine S.; James, Rachael H.; Connelly, Douglas P.; Hathorne, Ed C.</p> <p>2014-09-01</p> <p>The East Scotia subduction zone, located in the Atlantic sector of the Southern Ocean, hosts a number of <span class="hlt">hydrothermal</span> <span class="hlt">sites</span> in both back-arc and island-arc settings. High temperature (>348 °C) ‘black smoker’ vents have been sampled at three locations along segments E2 and E9 of the East Scotia back-arc spreading ridge, as well as ‘white smoker’ (<212 °C) and diffuse (<28 °C) <span class="hlt">hydrothermal</span> fluids from within the caldera of the Kemp submarine volcano. The composition of the endmember fluids (Mg = 0 mmol/kg) is markedly different, with pH ranging from <1 to 3.4, [Cl-] from ∼90 to 536 mM, [H2S] from 6.7 to ∼200 mM and [F-] from 35 to ∼1000 μM. All of the vent <span class="hlt">sites</span> are basalt- to basaltic andesite-hosted, providing an ideal opportunity for investigating the geochemical controls on rare earth element (REE) behaviour. Endmember <span class="hlt">hydrothermal</span> fluids from E2 and E9 have total REE concentrations ranging from 7.3 to 123 nmol/kg, and chondrite-normalised distribution patterns are either light REE-enriched (LaCN/YbCN = 12.8-30.0) with a positive europium anomaly (EuCN/Eu∗CN = 3.45-59.5), or mid REE-enriched (LaCN/NdCN = 0.61) with a negative Eu anomaly (EuCN/Eu∗CN = 0.59). By contrast, fluids from the Kemp Caldera have almost flat REE patterns (LaCN/YbCN = 2.1-2.2; EuCN/Eu∗CN = 1.2-2.2). We demonstrate that the REE geochemistry of fluids from the East Scotia back-arc spreading ridge is variably influenced by ion exchange with host minerals, phase separation, competitive complexation with ligands, and anhydrite deposition, whereas fluids from the Kemp submarine volcano are also affected by the injection of magmatic volatiles which enhances the solubility of all the REEs. We also show that the REE patterns of anhydrite deposits from Kemp differ from those of the present-day fluids, potentially providing critical information about the nature of <span class="hlt">hydrothermal</span> activity in the past, where access to <span class="hlt">hydrothermal</span> fluids is precluded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AGUFMOS43A0989S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AGUFMOS43A0989S&link_type=ABSTRACT"><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/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/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('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://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://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://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="http://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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AIPC.1731e0140K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AIPC.1731e0140K&link_type=ABSTRACT"><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://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://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://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> </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('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/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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E.632F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E.632F&link_type=ABSTRACT"><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://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://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="http://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://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/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://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/2012AGUFMOS22A..05N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS22A..05N"><span id="translatedtitle">Potential biomass in deep-sea <span class="hlt">hydrothermal</span> vent ecosystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, K.; Takai, K.</p> <p>2012-12-01</p> <p>Since the first discovery of black smoker vents hosting chemosynthetic macrofaunal communities (Spiess et al., 1980), submarine <span class="hlt">hydrothermal</span> systems and associated biota have attracted interest of many researchers (e.g., Humphris et al., 1995; Van Dover, 2000; Wilcock et al., 2004). In the past couple of decades, particular attention has been paid to chemolithoautotrophic microorganisms that sustain the <span class="hlt">hydrothermal</span> vent-endemic animal communities as the primary producer. This type of microorganisms obtains energy from inorganic substances (e.g., sulfur, hydrogen, and methane) derived from <span class="hlt">hydrothermal</span> vent fluids, and is often considered as an important modern analogue to the early ecosystems of the Earth as well as the extraterrestrial life in other planets and moons (e.g., Jannasch and Mottl, 1985; Nealson et al., 2005; Takai et al., 2006). Even today, however, the size of this type of chemosynthetic deep-sea <span class="hlt">hydrothermal</span> vent ecosystem is largely unknown. Here, we present geophysical and geochemical constraints on potential biomass in the deep-sea <span class="hlt">hydrothermal</span> vent ecosystem. The estimation of the potential biomass in the deep-sea <span class="hlt">hydrothermal</span> vent ecosystem is based on <span class="hlt">hydrothermal</span> fluid flux calculated from heat flux (Elderfield and Schltz, 1996), maximum chemical energy available from metabolic reactions during mixing between <span class="hlt">hydrothermal</span> vent fluids and seawater (McCollom, 2007), and maintenance energy requirements of the chemolithoautotrophic microorganisms (Hoehler, 2004). The result shows that the most of metabolic energy sustaining the deep-sea <span class="hlt">hydrothermal</span> vent ecosystem is produced by oxidation reaction of reduced sulfur, although some parts of the energy are derived from hydrogenotrophic and methanotrophic reactions. The overall total of the potential biomass in deep-sea <span class="hlt">hydrothermal</span> vent ecosystem is calculated to be much smaller than that in terrestrial ecosystems including terrestrial plants. The big difference in biomass between the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EPSC....8..679L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EPSC....8..679L"><span id="translatedtitle">Pyrrhotite catalyzes the synthesis of uracil under <span class="hlt">hydrothermal</span> conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>López Ibáñez de Aldecoa, A.; Menor-Salván, C.</p> <p>2013-09-01</p> <p>The hypothesis of a prebiotic origin for metabolic cycles in <span class="hlt">hydrothermal</span> systems gained interest during last years. The experimental approach to support this hypothesis was oriented mainly to the formation of organic molecules in iron sulfide mineral surfaces from inorganic precursors. In this work, we explore the behavior of previously formed, prebiotically plausible organic molecules in iron sulfide rich, low temperature <span class="hlt">hydrothermal</span> environments. Using urea as a starting point, we found that uracil and other nitrogen heterocycles could be synthesized using water-urea solution as precursor in a packed pyrrhotite bed reactor, simulating <span class="hlt">hydrothermal</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5901696','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5901696"><span id="translatedtitle">Predicting fluoride and chloride concentrations of <span class="hlt">hydrothermal</span> fluids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhu, Chen )</p> <p>1992-01-01</p> <p>A new method of predicting F and Cl concentrations of <span class="hlt">hydrothermal</span> fluids has been developed, which can be used to study water-rock interactions in a variety of <span class="hlt">hydrothermal</span>, metamorphic, and magnetic processes. This method is based on a comprehensive assessment of thermodynamic partitioning of F-Cl-OH between minerals and <span class="hlt">hydrothermal</span> fluids. The calculation method is explained. Fluid compositions obtained by applying this method to amphibolites from Hunts Brook Fault Zone, Connecticut, and to Santa Rita porphyry copper deposits, New Mexico, are similar to results obtained by metasomatism modeling and from fluid inclusion studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMOS21A1471M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMOS21A1471M&link_type=ABSTRACT"><span id="translatedtitle">Observation of <span class="hlt">hydrothermal</span> flows with acoustic video camera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mochizuki, M.; Asada, A.; Tamaki, K.; Scientific Team Of Yk09-13 Leg 1</p> <p>2010-12-01</p> <p>To evaluate <span class="hlt">hydrothermal</span> discharging and its diffusion process along the ocean ridge is necessary for understanding balance of mass and flux in the ocean, ecosystem around <span class="hlt">hydrothermal</span> fields and so on. However, it has been difficult for us to measure <span class="hlt">hydrothermal</span> activities without disturbance caused by observation platform ( submersible, ROV, AUV ). We wanted to have some observational method to observe <span class="hlt">hydrothermal</span> discharging behavior as it was. DIDSON (Dual-Frequency IDentification SONar) is acoustic lens-based sonar. It has sufficiently high resolution and rapid refresh rate that it can substitute for optical system in turbid or dark water where optical systems fail. DIDSON operates at two frequencies, 1.8MHz or 1.1MHz, and forms 96 beams spaced 0.3° apart or 48 beams spaced 0.6° apart respectively. It images out to 12m at 1.8MHz and 40m at 1.1MHz. The transmit and receive beams are formed with acoustic lenses with rectangular apertures and made of polymethylpentene plastic and FC-70 liquid. This physical beam forming allows DIDSON to consume only 30W of power. DIDSON updates its image between 20 to 1 frames/s depending on the operating frequency and the maximum range imaged. It communicates its host using Ethernet. Institute of Industrial Science, University of Tokyo ( IIS ) has understood DIDSON’s superior performance and tried to find new method for utilization of it. The observation systems that IIS has ever developed based on DIDSON are waterside surveillance system, automatic measurement system for fish length, automatic system for fish counting, diagnosis system for deterioration of underwater structure and so on. A next challenge is to develop an observation method based on DIDSON for <span class="hlt">hydrothermal</span> discharging from seafloor vent. We expected DIDSON to reveal whole image of <span class="hlt">hydrothermal</span> plume as well as detail inside the plume. In October 2009, we conducted seafloor reconnaissance using a manned deep-sea submersible Shinkai6500 in Central Indian</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023707','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023707"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> minerals and microstructures in the Silangkitang geothermal field along the Great Sumatran fault zone, Sumatra, Indonesia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Moore, Diane E.; Hickman, S.; Lockner, D.A.; Dobson, P.F.</p> <p>2001-01-01</p> <p>Detailed study of core samples of silicic tuff recovered from three geothermal wells along the strike-slip Great Sumatran fault zone near Silangkitang, North Sumatra, supports a model for enhanced <span class="hlt">hydrothermal</span> circulation adjacent to this major plate-boundary fault. Two wells (A and C) were drilled nearly vertically ??1 km southwest of the eastern (i.e., the principal) fault trace, and the third, directional well (B) was drilled eastward from the <span class="hlt">site</span> of well A to within ??100 m of the principal fault trace. The examined core samples come from depths of 1650-2120 m at measured well temperatures of 180-320 ??C. The samples collected near the principal fault trace have the highest temperatures, the largest amount of secondary pore space that correlates with high secondary permeability, and the most extensive <span class="hlt">hydrothermal</span> mineral development. Secondary permeability and the degree of <span class="hlt">hydrothermal</span> alteration decrease toward the southwestern margin of the fault zone. These features indicate episodic, localized flow of hot, possibly CO2-rich fluids within the fault zone. The microstructure populations identified in the core samples correlate to the subsidiary fault patterns typical of strike-slip faults. The geothermal reservoir appears to be centered on the fault zone, with the principal fault strands and adjoining, highly fractured and <span class="hlt">hydrothermally</span> altered rock serving as the main conduits for vertical fluid flow and advective heat transport from deeper magmatic sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26375668','PUBMED'); return false;" href="http://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="http://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 geographical area. Specific mesophilic, thermophilic and hyperthermophilic archaeal (e.g., Archaeoglobus, ANME-1) and bacterial (e.g., Caldithrix, Thermodesulfobacteria) taxa were highly abundant near the vent chimney. In contrast, bathyal-associated members affiliated to more ubiquitous phylogroups from deep-ocean sediments (e.g., Thaumarchaeota MGI, Gamma- and Alphaproteobacteria). This study provides a broader picture of the biological diversity and microbial biogeography, and represents a preliminary approach to the microbial ecology associated with the deep-sea sediments from the Menez Gwen <span class="hlt">hydrothermal</span> vent field. PMID:26375668</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010GeoOD..52..800M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010GeoOD..52..800M&link_type=ABSTRACT"><span id="translatedtitle">Noble-metal mineralization in the Semenov-2 <span class="hlt">hydrothermal</span> field (13°31'N), 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>Melekestseva, I. Yu.; Kotlyarov, V. A.; Khvorov, P. V.; Ivanov, V. N.; Beltenev, V. E.; Dobretsova, I. G.</p> <p>2010-12-01</p> <p>The porous fine-grained to microcrystalline copper-zinc ore of the Semenov-2 <span class="hlt">hydrothermal</span> field, a <span class="hlt">site</span> in the Semenov <span class="hlt">hydrothermal</span> cluster discovered in 2007 (13°31'N, MAR), is anomalously enriched in Au (22-188 ppm) and Ag (127-1787 ppm). Chalcopyrite, isocubanite, würtzite, and opal are major minerals; sphalerite, marcasite, pyrite, and covellite are auxiliary; and galena, pyrrhotite, native gold, silver telluride, barite, and aragonite are sporadic. Gold containing 0.31 to 23.07 wt % Ag occurs as up to 9-μm-sized subhedral, dendritelike, and elongated grains mostly hosted in opal and less frequently in sphalerite and in pores within isocubanite-chalcopyrite aggregate. An elongated grain (2 × 4 μm in size) of the Ag-Te phase was found in a pore. So far only basalts have been dredged from the Semenov-2 field, but anomalous gold and silver concentrations suggest the influence of ultramafic rocks; the latter were found 1.5 km westward, in the Semenov-1 <span class="hlt">hydrothermal</span> field. Mineral assemblage and morphology of gold particles indicate its primary origin in contrast to the <span class="hlt">hydrothermal</span> fields hosted in basalts, where gold is a product of remobilization. Zonal gold grains, found on oceanic floor for the first time, are characterized by low Ag content in the cores and high Ag content in the outer rims, reflecting variation in formation conditions.</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('http://www.ncbi.nlm.nih.gov/pubmed/26154881','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26154881"><span id="translatedtitle">RNA Oligomerization in Laboratory Analogues of Alkaline <span class="hlt">Hydrothermal</span> Vent Systems.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burcar, Bradley T; Barge, Laura M; Trail, Dustin; Watson, E Bruce; Russell, Michael J; McGown, Linda B</p> <p>2015-07-01</p> <p>Discovering pathways leading to long-chain RNA formation under feasible prebiotic conditions is an essential step toward demonstrating the viability of the RNA World hypothesis. Intensive research efforts have provided evidence of RNA oligomerization by using circular ribonucleotides, imidazole-activated ribonucleotides with montmorillonite catalyst, and ribonucleotides in the presence of lipids. Additionally, mineral surfaces such as borates, apatite, and calcite have been shown to catalyze the formation of small organic compounds from inorganic precursors (Cleaves, 2008 ), pointing to possible geological <span class="hlt">sites</span> for the origins of life. Indeed, the catalytic properties of these particular minerals provide compelling evidence for alkaline <span class="hlt">hydrothermal</span> vents as a potential <span class="hlt">site</span> for the origins of life since, at these vents, large metal-rich chimney structures can form that have been shown to be energetically favorable to diverse forms of life. Here, we test the ability of iron- and sulfur-rich chimneys to support RNA oligomerization reactions using imidazole-activated and non-activated ribonucleotides. The chimneys were synthesized in the laboratory in aqueous "ocean" solutions under conditions consistent with current understanding of early Earth. Effects of elemental composition, pH, inclusion of catalytic montmorillonite clay, doping of chimneys with small organic compounds, and in situ ribonucleotide activation on RNA polymerization were investigated. These experiments, under certain conditions, showed successful dimerization by using unmodified ribonucleotides, with the generation of RNA oligomers up to 4 units in length when imidazole-activated ribonucleotides were used instead. Elemental analysis of the chimney precipitates and the reaction solutions showed that most of the metal cations that were determined were preferentially partitioned into the chimneys. PMID:26154881</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2031H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2031H"><span id="translatedtitle">Microbial Response to High Temperature <span class="hlt">Hydrothermal</span> Forcing: AISICS Vent (Lucky Strike, 37°N, MAR) and Prokaryote Community as Example.</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.; Chavagnac, V.; Degboe, J.; Destrigneville, C.; Boulart, C.; Lesongeur, F.; Castillo, A.; Goodfroy, A.</p> <p>2015-12-01</p> <p>To study the <span class="hlt">hydrothermal</span> forcing on microbial colonization, and impacts on the oceanic crust alteration, an integrated study was led at the Tour Eiffel <span class="hlt">hydrothermal</span> <span class="hlt">site</span> (Lucky Strike <span class="hlt">hydrothermal</span> field, 37°N, MAR). We benefited from an annual survey between 2009 and 2011 of temperatures, along with sampling of focused and diffused fluids for chemical analysis, and chimney sampling and samples from microbial colonization experiments analyzed for prokaryotic composition and rock alteration study. The chemical composition of the fluids show an important increase in the CO2 concentration at the Eiffel Tower <span class="hlt">site</span> between 2009 and 2010 followed by a decrease between 2010 and 2011. In 2011, several fluid samples show an important depletion in Si, suggesting that some Si was removed by interaction with the stockwork before emission. Our observations, regarding the previous studies of chemical fluid affected by a magmatic event lead us to suppose that a magmatic/tectonic event occurred under the Lucky Strike <span class="hlt">hydrothermal</span> field between 2009 and 2010. The results of the prokaryotic communities' analysis show that a shift occurred in the dominant microbial metabolisms present in the colonizer retrieved in 2010 and the one retrieved in 2011. Archaeal communities shifted from chemolithoautotropic sulfite/thiosulfate reducers-dominated in 2010 to ammonia oxidizers-dominated in 2011. The bacterial communities also undergo a shift, from a community with diversified metabolisms in 2010 to a community strongly dominated by chemolithoautotrophic sulfide or hydrogen oxidation in 2011. Moreover, in terms of ecological preferendum, the Archaeal communities shifted from thermophilic-dominated to mesophilic-dominated. The present study underline the influence of modifications in gases compositions of <span class="hlt">hydrothermal</span> fluids subsequently to a degassing of the magma chamber and their impact on the microbial communities living in the vicinity of <span class="hlt">hydrothermal</span> vents at the Eiffel Tower <span class="hlt">site</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.449..186B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.449..186B"><span id="translatedtitle">How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of <span class="hlt">hydrothermal</span> discharge locations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, Edward T.; Resing, Joseph A.; Haymon, Rachel M.; Tunnicliffe, Verena; Lavelle, J. William; Martinez, Fernando; Ferrini, Vicki; Walker, Sharon L.; Nakamura, Koichi</p> <p>2016-09-01</p> <p>Decades of exploration for venting <span class="hlt">sites</span> along spreading ridge crests have produced global datasets that yield estimated mean <span class="hlt">site</span> spacings of ∼ 12- 220 km. This conclusion demands that <span class="hlt">sites</span> where <span class="hlt">hydrothermal</span> fluid leaks from the seafloor are improbably rare along the 66 000 km global ridge system, despite the high bulk permeability of ridge crest axes. However, to date, exploration methods have neither reliably detected plumes from isolated low-temperature, particle-poor, diffuse sources, nor differentiated individual, closely spaced (clustered within a few kilometers) <span class="hlt">sites</span> of any kind. Here we describe a much lower mean discharge spacing of 3-20 km, revealed by towing real-time oxidation-reduction-potential and optical sensors continuously along four fast- and intermediate-rate (>55 mm/yr) spreading ridge sections totaling 1470 km length. This closer spacing reflects both discovery of isolated <span class="hlt">sites</span> discharging particle-poor plumes (25% of all <span class="hlt">sites</span>) and improved discrimination (at a spatial resolution of ∼1 km) among clustered discrete and diffuse sources. Consequently, the number of active vent <span class="hlt">sites</span> on fast- and intermediate-rate spreading ridges may be at least a factor of 3-6 higher than now presumed. This increase provides new quantitative constraints for models of seafloor processes such as dispersal of fauna among seafloor and crustal chemosynthetic habitats, biogeochemical impacts of diffuse venting, and spatial patterns of <span class="hlt">hydrothermal</span> discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.449..186B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.449..186B&link_type=ABSTRACT"><span id="translatedtitle">How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of <span class="hlt">hydrothermal</span> discharge locations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, Edward T.; Resing, Joseph A.; Haymon, Rachel M.; Tunnicliffe, Verena; Lavelle, J. William; Martinez, Fernando; Ferrini, Vicki; Walker, Sharon L.; Nakamura, Koichi</p> <p>2016-09-01</p> <p>Decades of exploration for venting <span class="hlt">sites</span> along spreading ridge crests have produced global datasets that yield estimated mean <span class="hlt">site</span> spacings of ∼ 12- 220 km. This conclusion demands that <span class="hlt">sites</span> where <span class="hlt">hydrothermal</span> fluid leaks from the seafloor are improbably rare along the 66 000 km global ridge system, despite the high bulk permeability of ridge crest axes. However, to date, exploration methods have neither reliably detected plumes from isolated low-temperature, particle-poor, diffuse sources, nor differentiated individual, closely spaced (clustered within a few kilometers) <span class="hlt">sites</span> of any kind. Here we describe a much lower mean discharge spacing of 3-20 km, revealed by towing real-time oxidation-reduction-potential and optical sensors continuously along four fast- and intermediate-rate (>55 mm/yr) spreading ridge sections totaling 1470 km length. This closer spacing reflects both discovery of isolated <span class="hlt">sites</span> discharging particle-poor plumes (25% of all <span class="hlt">sites</span>) and improved discrimination (at a spatial resolution of ∼1 km) among clustered discrete and diffuse sources. Consequently, the number of active vent <span class="hlt">sites</span> on fast- and intermediate-rate spreading ridges may be at least a factor of 3-6 higher than now presumed. This increase provides new quantitative constraints for models of seafloor processes such as dispersal of fauna among seafloor and crustal chemosynthetic habitats, biogeochemical impacts of diffuse venting, and spatial patterns of <span class="hlt">hydrothermal</span> discharge.</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://www.ncbi.nlm.nih.gov/pubmed/11962668','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11962668"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> modification of titanium surface in calcium solutions.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hamad, Kenichi; Kon, Masayuki; Hanawa, Takao; Yokoyama, Ken'ichi; Miyamoto, Youji; Asaoka, Kenzo</p> <p>2002-05-01</p> <p><span class="hlt">Hydrothermal</span> modification of a titanium surface in calcium solutions was performed. The apatite precipitation on the modified surface in Hanks' solution, as a simulated body fluid, was evaluated and the surface microstructure changes after the modification were characterized by thin-film X-ray diffractometry (TF-XRD) and X-ray photoelectron spectroscopy (XPS). <span class="hlt">Hydrothermal</span> modification in CaO solution enhanced the precipitation of apatite on the titanium surface. High pH, high pressure and high temperature of the CaO solution increased the thickness of the surface-modified layer and enhanced the synthesis of calcium titanate which possibly promoted the precipitation of apatite in Hanks' solution. <span class="hlt">Hydrothermal</span> modification in CaCl2 solution, on the other hand, showed reverse effects. The modification of titanium in CaO solution with <span class="hlt">hydrothermal</span> treatment is expected to result in excellent osteointegration and can be easily performed by using an autoclave, a clinical apparatus widely used. PMID:11962668</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1165327','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1165327"><span id="translatedtitle">Whole Algae <span class="hlt">Hydrothermal</span> Liquefaction: 2014 State of Technology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jones, Susanne B.; Zhu, Yunhua; Snowden-Swan, Lesley J.; Anderson, Daniel; Hallen, Richard T.; Schmidt, Andrew J.; Albrecht, Karl O.; Elliott, Douglas C.</p> <p>2014-07-30</p> <p>This report describes the base case yields and operating conditions for converting whole microalgae via <span class="hlt">hydrothermal</span> liquefaction and upgrading to liquid fuels. This serves as the basis against which future technical improvements will be measured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5911393','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5911393"><span id="translatedtitle">Direct use of <span class="hlt">hydrothermal</span> energy: a review of environmental aspects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>O'Banion, K.; Layton, D.</p> <p>1981-08-28</p> <p>The potential environmental impacts of the exploration, development, and production of <span class="hlt">hydrothermal</span> geothermal energy for direct use applications are reviewed and evaluated. Mitigation strategies and research and development needs are included. (MHR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020046438&hterms=hydrothermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhydrothermal','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020046438&hterms=hydrothermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhydrothermal"><span id="translatedtitle">Impact-induced <span class="hlt">Hydrothermal</span> Systems and Mineral Deposition on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thorsos, I. E.; Newsom, H. E.; Davies, A. G.</p> <p>2002-01-01</p> <p>Modeling of <span class="hlt">hydrothermal</span> circulation at impact craters on Mars to determine system duration and potential mineral deposition in the context of Mars exploration. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19166335','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19166335"><span id="translatedtitle">Physicochemical properties of <span class="hlt">hydrothermally</span> treated hemicellulose from oil palm frond.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fazilah, Ariffin; Azemi, Mohamed N Mohd; Karim, Alias A; Norakma, Mohd N</p> <p>2009-02-25</p> <p>Hemicelluloses from oil palm frond (OPF) were extracted using 3 M potassium hydroxide (KOH) for 4 h at 40 degrees C with stirring at 400 rpm to obtain hemicelluloses A and B. The total yield of the hemicellulose isolated from OPF was 33% (dry weight). Both hemicelluloses A and B were then subjected to <span class="hlt">hydrothermal</span> treatment at 121 degrees C and 1.03 x 10(5) Pa for 10, 30, and 50 min. Physicochemical characterizations of <span class="hlt">hydrothermally</span> treated hemicelluloses, such as Klason lignin content and reducing sugar content, were performed to study the effect of autohydrolysis processing on OPF-derived hemicelluloses. It was shown that Klason lignin content in hemicellulose A was higher than that in hemicellulose B and decreased after <span class="hlt">hydrothermal</span> treatment. <span class="hlt">Hydrothermal</span> treatment enhanced the solubility of hemicelluloses, which reflects their higher reducing sugar content. Monosaccharide analysis using HPLC showed that xylose was the predominant monosaccharide for both hemicelluloses A and B. PMID:19166335</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS41C1740M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS41C1740M"><span id="translatedtitle">Development of acoustic observation method for seafloor <span class="hlt">hydrothermal</span> flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mochizuki, M.; Tamura, H.; Asada, A.; Kinoshita, M.; Tamaki, K.</p> <p>2012-12-01</p> <p>In October 2009, we conducted seafloor reconnaissance using a manned deep-sea submersible Shinkai6500 in Central Indian Ridge 18-20deg.S, where <span class="hlt">hydrothermal</span> plume signatures were previously perceived. Acoustic video camera "DIDSON" was equipped on the top of Shinkai6500 in order to get acoustic video images of <span class="hlt">hydrothermal</span> plumes. The acoustic video images of the <span class="hlt">hydrothermal</span> plumes had been captured in three of seven dives. We could identify shadings inside the acoustic video images of the <span class="hlt">hydrothermal</span> plumes. Silhouettes of the <span class="hlt">hydrothermal</span> plumes varied from second to second, and the shadings inside them also varied. These variations corresponded to internal structures and flows of the plumes. DIDSON (Dual-Frequency IDentification SONar) is acoustic lens-based sonar. It has sufficiently high resolution and rapid refresh rate that it can substitute for optical system in turbid or dark water where optical systems fail. Ins. of Industrial Science, University of Tokyo has understood DIDSON's superior performance and tried to develop a new observation method based on DIDSON for <span class="hlt">hydrothermal</span> discharging from seafloor vent. We expected DIDSON to reveal whole image of <span class="hlt">hydrothermal</span> plume as well as detail inside the plume. The proposed method to observe and measure <span class="hlt">hydrothermal</span> flow is the one to utilize a sheet-like acoustic beam. Scanning with concentrated acoustic beam gives distances to the edges of the <span class="hlt">hydrothermal</span> flows. And then, the shapes of the flows can be identified even in low and zero visibility conditions. Tank experiment was conducted. The purposes of this experiment were to make an attempt at proposed method to delineate underwater <span class="hlt">hydrothermal</span> flows and to understand relationships among acoustic video image, flow rate and water temperature. Water was heated in the hot tub and pumped to the water tank through the silicon tube. We observed water flows discharging from the tip of the tube with DIDSON. Flow rate had been controlled and temperatures of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..1615842B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..1615842B&link_type=ABSTRACT"><span id="translatedtitle">Geochemistry driven trends in microbial diversity and function across a temperature transect of a shallow water <span class="hlt">hydrothermal</span> system off Milos (Greece)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bühring, Solveig I.; Amend, Jan P.; Gómez Sáez, Gonzalo V.; Häusler, Stefan; Hinrichs, Kai-Uwe; Pichler, Thomas; Pop Ristova, Petra; Price, Roy E.; Santi, Ioulia; Sollich, Miriam</p> <p>2014-05-01</p> <p>The shallow water <span class="hlt">hydrothermal</span> vents off Milos Island, Greece, discharge hot, slightly acidic, reduced fluids into colder, slightly alkaline, oxygenated seawater. Gradients in temperature, pH, and geochemistry are established as the two fluids mix, leading to the formation of various microbial microniches. In contrast to deep-sea <span class="hlt">hydrothermal</span> systems, the availability of sun light allows for a combination of photo- and chemotrophic carbon fixation. Despite the comparably easy accessibility of shallow water <span class="hlt">hydrothermal</span> systems, little is known about their microbial diversity and functioning. We present data from a shallow <span class="hlt">hydrothermal</span> system off Milos Island, one of the most <span class="hlt">hydrothermally</span> active regions in the Mediterranean Sea. The physico-chemical changes from ambient seafloor to <span class="hlt">hydrothermal</span> area were investigated and documented by in situ microsensor profiling of temperature, pH, total reduced sulfur and dissolved oxygen alongside porewater geochemistry. The spatial microbial diversity was determined using a combination of gene- and lipid-based approaches, whereas microbial functioning was assessed by stable isotope probing experiments targeting lipid biomarkers. In situ microprofiles indicated an extreme environment with steep gradients, offering a variety of microniches for metabolically diverse microbial communities. We sampled a transect along a <span class="hlt">hydrothermal</span> patch, following an increase in sediment surface temperature from background to 90°C, including five sampling points up to 20 cm sediment depth. Investigation of the bacterial diversity using ARISA revealed differences in the community structure along the geochemical gradients, with the least similarity between the ambient and highly <span class="hlt">hydrothermally</span> impacted <span class="hlt">sites</span>. Furthermore, using multivariate statistical analyses it was shown that variations in the community structure could be attributed to differences in the sediment geochemistry and especially the sulfide content, and only indirectly to shifts in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B13A0173H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B13A0173H"><span id="translatedtitle">Evidence for Pulsed <span class="hlt">Hydrothermal</span> Venting from Young Abyssal Hills on the EPR Flank Suggests Frequent Seismic Pumping of Ridge Flank Fluid Flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haymon, R. M.; MacDonald, K. C.; Benjamin, S. B.; Ehrhardt, C. J.</p> <p>2004-12-01</p> <p>Although measured heat flow suggests that 40-50% of oceanic <span class="hlt">hydrothermal</span> heat and fluid flux is from young (0.1-5 Ma) abyssal hill terrain on MOR flanks, <span class="hlt">hydrothermal</span> vents in this setting rarely have been found. On the EPR flanks, seafloor evidence of venting from abyssal hills has been discovered recently at two <span class="hlt">sites</span>: on ˜0.1 Ma seafloor at 10° 20'N, 103° 33.2'W ("Tevnia <span class="hlt">Site</span>") and on ˜0.5 Ma seafloor at 9° 27'N, 104° 32.3'W ("Macrobes <span class="hlt">Site</span>"). Manifestations of venting at these <span class="hlt">sites</span> 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 "blow-outs." <span class="hlt">Hydrothermal</span> deposits recovered at the ˜0.1 Ma "Tevnia <span class="hlt">Site</span>" are fault breccias that record many episodes of brecciation followed by <span class="hlt">hydrothermal</span> cementation (Benjamin et al., this session). Tubeworm casings, live crabs, and "dandelions" observed at this <span class="hlt">site</span> indicate that the most recent episode of venting was active during, or shortly before, this <span class="hlt">site</span> was visited with Alvin in 1994. To create the 200 m-high axis-facing fault scarp at Tevnia <span class="hlt">Site</span> in 100,000 years, an average uplift rate of at least 2 cm/y is required. Since off-axis earthquakes located on abyssal hill fault scarps typically are <M5, it is likely that each episode of slip has small vertical displacement (a few cm). Therefore fault slippage must repeat on a decadal timescale to match the observed rate of hill uplift, probably breaking open the fault scarp and rejuvenating <span class="hlt">hydrothermal</span> flow on a very frequent basis. In addition, close proximity to Clipperton Transform may subject Tevnia <span class="hlt">Site</span> to frequent M5-M6 seismic events with strong ground shaking and hydraulic pressure pulses capable of breaking open subseafloor pathways clogged with fragile minerals. We hypothesize that the multiple brecciation/cementation events recorded in the Tevnia <span class="hlt">Site</span> samples, and biological evidence for recent venting at the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS42A..07Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS42A..07Z"><span id="translatedtitle">Shallow water submarine <span class="hlt">hydrothermal</span> activity - A case study in the assessment of ocean acidification and fertilization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, J.; Yoshida, K.; Hagiwara, T.; Nagao, K.; Kusakabe, M.; Wang, B.; Chen, C. A.</p> <p>2012-12-01</p> <p>Most natural Shallow Water submarine <span class="hlt">Hydrothermal</span> activates (SWH) along coastlines are related to <span class="hlt">hydrothermal</span> eruptions involving heating of groundwater with the volcanic gas. These SWHs supply nutrients such as phosphorus and micro nutrients like iron to the euphotic zone, contributing to the overall natural fertility and primary productivity of coastal waters. However, SWHs also have a negative effect, dispersing toxic materials such as mercury and arsenic, and affecting the acidification of the surrounding waters. In this study, we evaluate the impact of "iron supply" and "ocean acidification" on the primary production in a coastal marine environment, at a SWH area discovered off Gueshandao Island, northeast Taiwan. In the past three years, expeditions were conducted and observations made around this SWH <span class="hlt">site</span>. Divers, small boats and a research vessel (R/V OR1, Ocean University National Taiwan) were used to survey successively larger areas around the <span class="hlt">site</span>. Some of the results obtained are as follows. <span class="hlt">Hydrothermal</span> vents are located in a hilly terrain rich with hot spring water with gas erupting intermittently. There are two types of vents, roughly divided by color, yellow hot spring water with higher temperature >110 degC ejected from sulfur chimneys of various sizes, and colorless water with lower temperature ~80 degC ejected directly from the crevices of the andesitic bedrock. Natural sulfur solidifying in the mouth of a small chimney was captured by a video camera, and explosions were also observed at intervals of a few minutes. Sediment, sand and particles of sulfur were deposited on the sides to a radius of about 50 m condensing around the chimney. The bottom type changes from sand/particles to outcrop/rock away from the vents. Moreover, gas samples were collected from the vents; the ratios of gas concentrations (N2/Ar) and isotopic composition of noble gas (3He/4He) suggest that these volcanic gases are mantle-derived. <span class="hlt">Hydrothermal</span> fluid with high p</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JGR....98.1813S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JGR....98.1813S"><span id="translatedtitle">Comment on 'Consequences of phase separation on the distribution of <span class="hlt">hydrothermal</span> fluids at ASHES vent field, axial volcano, Juan de Fuca ridge' by Christopher G. Fox</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scholl, M. A.; Ingebritsen, S. E.; Essaid, H. I.</p> <p>1993-02-01</p> <p>Fox (1990), in order to explain observations during the Axial Seamount <span class="hlt">Hydrothermal</span> Emissions Study (ASHES), proposed a conceptual model for a two-phase subsea <span class="hlt">hydrothermal</span> system in which steam controlled flow patterns by blocking liquid flow. An attempt is made here to demonstrate with a very general model that relative permeability contrasts by themselves do not cause spatial isolation of phases in steam/liquid water systems and that density segregation, independent of relative permeability effects, should not be ruled out as an explanation for the observations at the ASHES <span class="hlt">site</span>. Fox replies that density segregation is probably not the only mechanism at work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20023282','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20023282"><span id="translatedtitle">Methods to enhance the characteristics of <span class="hlt">hydrothermally</span> prepared slurry fuels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Anderson, C.M.; Musich, M.A.; Mann, M.D.; DeWall, R.A.; Richter, J.J.; Potas, T.A.; Willson, W.G.</p> <p>2000-04-25</p> <p>Methods are disclosed for enhancing the flow behavior and stability of <span class="hlt">hydrothermally</span> treated slurry fuels. A mechanical high-shear dispersion and homogenization device is used to shear the slurry fuel. Other improvements include blending the carbonaceous material with a form of coal to reduce or eliminate the flocculation of the slurry, and maintaining the temperature of the <span class="hlt">hydrothermal</span> treatment between approximately 300 to 350 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25195592','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25195592"><span id="translatedtitle"><span class="hlt">Hydrothermal</span> fabrication of three-dimensional secondary battery anodes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jinyun; Zhang, Hui Gang; Wang, Junjie; Cho, Jiung; Pikul, James H; Epstein, Eric S; Huang, Xingjiu; Liu, Jinhuai; King, William P; Braun, Paul V</p> <p>2014-11-01</p> <p>A generalized <span class="hlt">hydrothermal</span> strategy for fabricating three-dimensional (3D) battery electrodes is presented. The <span class="hlt">hydrothermal</span> growth deposits electrochemically active nanomaterials uniformly throughout the complex 3D mesostructure of the scaffold. Ni inverse opals coated with SnO2 nanoparticles or Co3O4 nanoplatelets, and SiO2 inverse opals coated with Fe3O4 are fabricated, all of which show attractive properties including good capacity retention and C-rate performances. PMID:25195592</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21156305','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21156305"><span id="translatedtitle">Novel technology for <span class="hlt">hydrothermal</span> treatment of NPP evaporator concentrates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Avramenko, Valentin; Dobrzhansky, Vitaly; Marinin, Dmitry; Sergienko, Valentin; Shmatko, Sergey</p> <p>2007-07-01</p> <p>A novel technology was developed for treatment of evaporator concentrates produced as a result of operation of evaporation devices comprising the main component of special water purification systems of nuclear power plants (NPP). The developed technology includes a <span class="hlt">hydrothermal</span> (T=250-300 deg. C and P=80-120 bar) processing of evaporator concentrates in oxidation medium in order to destruct stable organic complexes of cobalt radionuclides and remove these radionuclides by oxide materials formed during such a processing. The cesium radionuclides contained in evaporator concentrates are removed by a conventional method-through application of one of the developed composite sorbents with ferrocyanides of transition metals used as active agents. Extensive laboratory studies of the processes occurring in evaporator concentrates under <span class="hlt">hydrothermal</span> conditions were performed. It was shown that <span class="hlt">hydrothermal</span> oxidation of evaporator concentrates has a number of advantages as compared to traditional oxidation methods (ozonization, photo-catalytic, electrochemical and plasma oxidation). A laboratory installation was built for the flow-type <span class="hlt">hydrothermal</span> oxidation of NPP evaporator concentrates. The obtained experimental results showed good prospects for the developed method application. On the basis of the results obtained, a pilot installation of productivity up to 15 l/hour was developed and built in order to work out the technology of evaporator concentrates <span class="hlt">hydrothermal</span> treatment. The pilot tests of the <span class="hlt">hydrothermal</span> technology for evaporator concentrates <span class="hlt">hydrothermal</span> treatment were performed for 6 months in 2006 at the 1. reactor unit of the Novovoronezhskaya NPP (Voronezh Region, Russia). Optimal technological regimes were determined, and estimations of the economic soundness of the technology were made. The advantages of the presented technology in terms of management of concentrated liquid radioactive wastes (LRW) at nuclear cycle facilities, as compared to other methods</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6254717','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6254717"><span id="translatedtitle">Enhanced heat transfer in partially-saturated <span class="hlt">hydrothermal</span> systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bixler, N.E.; Carrigan, C.R.</p> <p>1986-01-01</p> <p>The role of capillarity is potentially important for determining heat transfer in <span class="hlt">hydrothermal</span> regions. Capillarity allows mixing of phases in liquid/vapor systems and results in enhanced two-phase convection. Comparisons involving a numerical model with capillarity and analytical models without indicate that heat transfer can be enhanced by about an order of magnitude. Whether capillarity can be important for a particular <span class="hlt">hydrothermal</span> region will depend on the nature of mineral precipitation as well as pore and fracture size distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DPS....4650008N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DPS....4650008N"><span id="translatedtitle">Core Cracking and <span class="hlt">Hydrothermal</span> Circulation Profoundly Affect Ceres' Geophysical Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neveu, Marc; Desch, Steven J.; Castillo-Rogez, Julie C.</p> <p>2014-11-01</p> <p>The dwarf planet (1)Ceres is about to be visited by the Dawn spacecraft [1]. In addition to a recent report of water vapor emission [2], observations and models of Ceres suggest that its evolution was shaped by interactions between liquid water and silicate rock [3,4].<span class="hlt">Hydrothermal</span> processes in a heated core require both fractured rock and liquid. Using a new core cracking model coupled to a thermal evolution code [5], we find volumes of fractured rock always large enough for significant interaction to occur. Therefore, liquid persistence is key. It is