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Sample records for endeavour hydrothermal system

  1. Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system

    SciTech Connect

    Brown, T A; Proskurowski, G; Lilley, M D

    2004-01-07

    Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.

  2. Geology of a vigorous hydrothermal system on the Endeavour segment, Juan de Fuca Ridge

    SciTech Connect

    Delaney, J.R.; Robigou, V.; McDuff, R.E. ); Tivey, M.K. )

    1992-12-10

    A high-precision, high-resolution geologic map explicitly documents relationships between tectonic features and large steep-sided, sulfide-sulfate-silica deposits in the vigorously venting Endeavour hydrothermal field near the northern end of the Juan de Fuca Ridge. Location of the most massive sulfide structures appears to be controlled by intersections of ridge-parallel normal faults and other fracture-fissure sets that trend oblique to, and perpendicular to the overall structural fabric of the axial valley. As presently mapped, the field is about 200 by 400 m on a side and contains at least 15 large (> 1,000 m[sup 3]) sulfide edifices and many tens of smaller, commonly inactive, sulfide structures. The larger sulfide structures are also the most vigorously venting features in the field; they are commonly more than 30 m in diameter and up to 20 m in height. Maximum venting temperatures of 375[degrees]C are associated with the smaller structures in the northern portion of the field are consistently 20[degrees]-30[degrees]C lower. Hydrothermal output from individual active sulfide features varies from no flow in the lower third of the edifice to vigorous output from fracture-controlled black smoker activity near the top of the structures. Two types of diffuse venting in the Endeavour field include a lower temperature 8[degrees]-15[degrees]C output through colonies of large tubeworms and 25[degrees]-50[degrees]C vent fluid that seems to percolate through the tops of overhanging flanges. The large size and steep-walled nature of these structures evidently results from sustained venting in a mature hydrothermal system, coupled with dual mineral depositional mechanisms involving vertical growth by accumulation of chimney sulfide debris and lateral growth by means of flange development.

  3. Geology and hydrothermal evolution of the Mothra Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Glickson, Deborah A.; Kelley, Deborah S.; Delaney, John R.

    2007-06-01

    Detailed characterization of the Mothra Hydrothermal Field, the most southern and spatially extensive field on the Endeavour Segment of the Juan de Fuca Ridge, provides new insights into its geologic and hydrothermal development. Meter-scale bathymetry, side-scan sonar imagery, and direct dive observations show that Mothra is composed of six actively venting sulfide clusters spaced 40-200 m apart. Chimneys within each cluster have similar morphology and venting characteristics, and all clusters host a combination of active and extinct sulfide structures. Black smoker chimneys venting fluids above 300°C are rare, while more common lower-temperature, diffusely venting chimneys support dense colonies of macrofauna and bacterial mat. Hydrothermal sediment and extinct sulfide debris cover 10-15 m of the seafloor surrounding each vent cluster, obscuring the underlying basaltic substrate of light to moderately sedimented pillow, lobate, sheet, and chaotic flows, basalt talus, and collapse terrain. Extinct sulfide chimneys and debris between the clusters indicate that hydrothermal flow was once more widespread and that it has shifted spatially over time. The most prominent structural features in the axial valley at Mothra are regional (020°) trending faults and fissures and north-south trending collapse basins. The location of actively venting clusters within the field is controlled by (1) localization of fluid upflow along the western boundary fault zone, and diversion of these fluids by antithetic faults to feed vent clusters near the western valley wall, and (2) tapping of residual magmatic heat in the central part of the axial valley, which drives flow beneath vent clusters directly adjacent to the collapse basins 70-90 m east of the western valley wall. These processes form the basis for a model of axial valley and hydrothermal system development at Mothra, in which the field is initiated by an eruptive-diking episode and sustained through intense microseismicity

  4. Time-series measurement of hydrothermal heat flux at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Xu, Guangyu; Jackson, Darrell R.; Bemis, Karen G.; Rona, Peter A.

    2014-10-01

    Continuous time-series observations are key to understanding the temporal evolution of a seafloor hydrothermal system and its interplay with thermal and chemical processes in the ocean and Earth interior. In this paper, we present a 26-month time series of the heat flux driving a hydrothermal plume on the Endeavour Segment of the Juan de Fuca Ridge obtained using the Cabled Observatory Vent Imaging Sonar (COVIS). Since 2010, COVIS has been connected to the North East Pacific Time-series Underwater Networked Experiment (NEPTUNE) observatory that provides power and real-time data transmission. The heat flux time series has a mean value of 18.10 MW and a standard deviation of 6.44 MW. The time series has no significant global trend, suggesting the hydrothermal heat source remained steady during the observation period. The steadiness of the hydrothermal heat source coincides with reduced seismic activity at Endeavour observed in the seismic data recorded by an ocean bottom seismometer from 2011 to 2013. Furthermore, first-order estimation of heat flux based on the temperature measurements made by the Benthic and Resistivity Sensors (BARS) at a neighboring vent also supports the steadiness of the hydrothermal heat source.

  5. High-resolution near-bottom vector magnetic anomalies over Raven Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Tivey, Maurice A.; Johnson, H. Paul; Salmi, Marie S.; Hutnak, Michael

    2014-10-01

    High-resolution, near-bottom vector magnetic data were collected by remotely operated vehicle Jason over the Raven hydrothermal 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 site using innovative thermal blanket technology to map the heat flux and crustal fluid pathways around a solitary hydrothermal vent field. Raven hydrothermal activity is presently located along the western axial valley wall, while additional inactive hydrothermal 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 hydrothermal 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 hydrothermal alteration. A general NW to SE trend in reduced magnetization across the Raven area correlates closely with the distribution of hydrothermal 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 hydrothermally altered zone directly beneath the Raven site is approximately 15 × 106 m3 in volume.

  6. Distribution of Particulates in Hydrothermal Plumes of the Endeavour Axial Valley: Preliminary Results from the Sea Breeze Project

    NASA Astrophysics Data System (ADS)

    Nassif, T. H.; McDuff, R. E.; Robigou, V.; Stahr, F.

    2004-12-01

    Hydrothermal vent plumes provide zones for chemical reactions between vent fluids and seawater, potential habitats for anaerobic bacteria and zooplankton, and a probable mechanism for the dispersal of vent larvae. Within the Endeavour Integrated Study Site are five known vent fields situated along the axial valley of the Endeavour Segment of the Juan de Fuca Ridge (N.E. Pacific Ocean). Each of these fields has a particle rich neutrally buoyant plume above it almost constantly, a common characteristic of vent systems worldwide. The purpose of this study was to determine 1) how plume particle distribution varies along the Endeavour segment axial valley; 2) whether a correlation exists between vent activity and particle density in the surrounding water, and 3) if the peak signals in backscatter and light transmission fall within a consistent range of potential density values along the axial valley. Light transmission and backscatter data were collected from vertically oscillating CTD casts at 21 stations along the axial valley covering the fields of Mothra, Main Endeavour, High Rise, Salty Dawg, and Sasquatch during the Sea Breeze - REVEL 2004 seagoing program. Plume particle density within ocean water was measured using a Wetlabs transmissometer and a Seapoint turbidity sensor. Preliminary results indicate a positive correlation between "black smoker" activity and signal strength in backscatter and light transmission. Main Endeavour and High Rise, known to exhibit the most rigorous hydrothermal activity, show correspondingly high amplitude signals in both backscatter and light transmission. Predicted diurnal currents seem to effect lateral plume particle movement away from vent sources, greatly impacting the particle density in surrounding areas. Peak signals in backscatter and light transmission occur in less dense water moving northward from Mothra to Salty Dawg.

  7. Heat flux measured acoustically at Grotto Vent, a hydrothermal vent cluster on the Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2013-12-01

    Over the past several decades, quantifying the heat output has been a unanimous focus of studies at hydrothermal vent fields discovered around the global ocean. Despite their importance, direct measurements of hydrothermal heat flux are very limited due to the remoteness of most vent sites and the complexity of hydrothermal 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 hydrothermal system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://sites.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 hydrothermal 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 hydrothermal 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 hydrothermal plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).

  8. Hydrothermal sulfide accumulation along the Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Jamieson, J. W.; Clague, D. A.; Hannington, M. D.

    2014-06-01

    Hydrothermal sulfide deposits that form on the seafloor are often located by the detection of hydrothermal plumes in the water column, followed by exploration with deep-towed cameras, side-scan sonar imaging, and finally by visual surveys using remotely-operated vehicle or occupied submersible. Hydrothermal plume detection, however, is ineffective for finding hydrothermally-inactive sulfide deposits, which may represent a significant amount of the total sulfide accumulation on the seafloor, even in hydrothermally active settings. Here, we present results from recent high-resolution, autonomous underwater vehicle-based mapping of the hydrothermally-active Endeavour Segment of the Juan de Fuca Ridge, in the Northeast Pacific Ocean. Analysis of the ridge bathymetry resulted in the location of 581 individual sulfide deposits along 24 km of ridge length. Hydrothermal deposits were distinguished from volcanic and tectonic features based on the characteristics of their surface morphology, such as shape and slope angles. Volume calculations for each deposit results in a total volume of 372,500 m3 of hydrothermal sulfide-sulfate-silica material, for an equivalent mass of ∼1.2 Mt of hydrothermal material on the seafloor within the ridge's axial valley, assuming a density of 3.1 g/cm3. Much of this total volume is from previously undocumented inactive deposits outside the main active vent fields. Based on minimum ages of sulfide deposition, the deposits accumulated at a maximum rate of ∼400 t/yr, with a depositional efficiency (proportion of hydrothermal material that accumulates on the seafloor to the total amount hydrothermally mobilized and transported to the seafloor) of ∼5%. The calculated sulfide tonnage represents a four-fold increase over previous sulfide estimates for the Endeavour Segment that were based largely on accumulations from within the active fields. These results suggest that recent global seafloor sulfide resource estimates, which were based mostly

  9. Recent Investigation of In-Situ pH in Hydrothermal Vent Fluids at Main Endeavour Field (MEF) and ASHES Vent Field (ASHES): Implications for Dynamic Changes in Subseafloor Hydrothermal System

    NASA Astrophysics Data System (ADS)

    Ding, K.; Seyfried, W. E., Jr.; Tan, C.; Schaen, A. T.; Luhmann, A. J.

    2014-12-01

    In-situ pH is among the key factors affecting chemical reactions involved with fluid-rock interaction and metal transport in hydrothermal systems. A small variation in pH will often result in a large difference in dissolved metal concentrations. For instance, at 400oC, a decrease of ~0.15 pH unit will cause dissolved Fe concentration to double in fluid coexisting with a Fe-bearing mineral assemblage. This parameter also offers us an opportunity to better understand processes controlling the temporal evolution of hydrothermal vent fluid chemistry at mid-ocean ridges. During our recent cruise AT 26-17 with newly upgraded DSV2 Alvin, in-situ measurements of pH were carried out along with gas-tight sampling of vent fluids. Our efforts were focused at MEF and ASHES on the Juan de Fuca Ridge. These hydrothermal systems have been shown to be particularly responsive to subseafloor seismic and magmatic events. The measured fluid temperature was approximately 333˚C and 300˚C at Dante vent orifice of MEF and Inferno vent orifice of ASHES, respectively. The corresponding measured in-situ pH values for both vents are: 4.94 and 4.88, respectively. Dissolved gases and other species were also measured from gas-tight fluid samples providing a means of comparison with the in-situ data. As we have known the earthquake and magmatic activity often places the system at higher temperature and more reducing conditions in connection with a new evolutionary cycle. Comparing these relatively low in-situ pH values with those measured in the past, especially with the ones obtained at MEF in 1999 after an intense swarm of earthquakes, we see the system trending towards more acidic conditions along with decreasing temperature and dissolved H2 and H2S. Taking an example from Dante vent site, in-situ pH value of 5.15 was recorded with a measured temperature of 363oC two month after the event in 1999, which gives 0.2 pH unit greater than the more recent data. Measured dissolved H2 and H2S

  10. Ascending and descending particle flux from hydrothermal plumes at Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Cowen, James P.; Bertram, Miriam A.; Wakeham, Stuart G.; Thomson, Richard E.; William Lavelle, J.; Baker, Edward T.; Feely, Richard A.

    2001-04-01

    Bio-acoustic surveys and associated zooplankton net tows have documented anomalously high concentrations of zooplankton within a 100 m layer above the hydrothermal plumes at Endeavour Segment, Juan de Fuca Ridge. These and other data suggest that congregating epi-plume zooplankton are exploiting a food substrate associated with the hydrothermal plume. Ascending, organic-rich particles could provide a connection. Consequently, two paired sequentially sampling ascending and descending particle flux traps and a current meter were deployed on each of three moorings from July 1994 to May 1995. Mooring sites included an on-axis site (OAS; 47°57.0'N, 129°05.7'W) near the main Endeavour vent field, a "down-current" site 3 km west of the main vent field (WS), and a third background station 43 km northeast of the vent field (ES). Significant ascending and descending particle fluxes were measured at all sites and depths. Lipid analyses indicated that ascending POC was derived from mid-depth and deep zooplankton whereas descending POC also contained a component of photosynthetically derived products from the sea surface. Highest ascending POC fluxes were found at the hydrothermal plume-swept sites (OAS and WS). The limited data available, however, precludes an unequivocal conclusion that hydrothermal processes contribute to the ascending flux of organic carbon at each site. Highest ascending to descending POC flux ratios were also found at WS. Observed trends in POC, PMn/PTi, and PFe/PTi clearly support a hydrothermal component to the descending flux at the plume-swept WS site (no descending data was recovered at OAS) but not at the background ES site. Alternative explanations for ascending particle data are discussed. First-order calculations for the organic carbon input (5-22 mg C m -2 d -1) required to sustain observed epi-plume zooplankton anomalies at Endeavour are comparable both to measured total POC flux to epi-plume depths (2-5 mg C m -2 d -1: combined hydrothermal

  11. Precipitation and growth of barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    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

    2016-01-01

    Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, barite (BaSO4) is unique because it requires the direct mixing of Ba-rich hydrothermal 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 hydrothermal 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 hydrothermal 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 hydrothermal 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% hydrothermal 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% hydrothermal 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 hydrothermal fluid. Fluid inclusions within barite indicate formation temperatures of between ∼120 °C and 240 °C during

  12. Magnetite formation from ferrihydrite by hyperthermophilic archaea from Endeavour Segment, Juan de Fuca Ridge hydrothermal vent chimneys.

    PubMed

    Lin, T Jennifer; Breves, E A; Dyar, M D; Ver Eecke, H C; Jamieson, J W; Holden, J F

    2014-05-01

    Hyperthermophilic iron reducers are common in hydrothermal chimneys found along the Endeavour Segment in the northeastern Pacific Ocean based on culture-dependent estimates. However, information on the availability of Fe(III) (oxyhydr) oxides within these chimneys, the types of Fe(III) (oxyhydr) oxides utilized by the organisms, rates and environmental constraints of hyperthermophilic iron reduction, and mineral end products is needed to determine their biogeochemical significance and are addressed in this study. Thin-section petrography on the interior of a hydrothermal chimney from the Dante edifice at Endeavour showed a thin coat of Fe(III) (oxyhydr) oxide associated with amorphous silica on the exposed outer surfaces of pyrrhotite, sphalerite, and chalcopyrite in pore spaces, along with anhydrite precipitation in the pores that is indicative of seawater ingress. The iron sulfide minerals were likely oxidized to Fe(III) (oxyhydr) oxide with increasing pH and Eh due to cooling and seawater exposure, providing reactants for bioreduction. Culture-dependent estimates of hyperthermophilic iron reducer abundances in this sample were 1740 and 10 cells per gram (dry weight) of material from the outer surface and the marcasite-sphalerite-rich interior, respectively. Two hyperthermophilic iron reducers, Hyperthermus sp. Ro04 and Pyrodictium sp. Su06, were isolated from other active hydrothermal chimneys on the Endeavour Segment. Strain Ro04 is a neutrophilic (pH opt 7-8) heterotroph, while strain Su06 is a mildly acidophilic (pH opt 5), hydrogenotrophic autotroph, both with optimal growth temperatures of 90-92 °C. Mössbauer spectroscopy of the iron oxides before and after growth demonstrated that both organisms form nanophase (<12 nm) magnetite [Fe3 O4 ] from laboratory-synthesized ferrihydrite [Fe10 O14 (OH)2 ] with no detectable mineral intermediates. They produced up to 40 mm Fe(2+) in a growth-dependent manner, while all abiotic and biotic controls produced <3 mm Fe

  13. Evolution of the Mothra Hydrothermal Field, Endeavour Segment of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Glickson, D.; Kelley, D. S.; Delaney, J.

    2005-12-01

    The Mothra Hydrothermal Field (MHF) is a 600 m long, high-temperature hydrothermal field. It is located 2.7 km south of the Main Endeavour Field at the southern end of the central Endeavour Segment. Mothra is the most areally extensive field along the Endeavour Segment, composed of six active sulfide clusters that are 40-200 m apart. Each cluster contains rare black smokers (venting up to 319°C), numerous diffusely venting chimneys, and abundant extinct chimneys and sulfide talus. From north to south, these clusters include Cauldron, Twin Peaks, Faulty Towers, Crab Basin, Cuchalainn, and Stonehenge. As part of the Endeavour Integrated Study Site (ISS), the MHF is a site of intensive interdisciplinary studies focused on linkages among geology, geochemistry, fluid chemistry, seismology, and microbiology. Axial valley geology at MHF is structurally complex, consisting of lightly fissured flows that abut the walls and surround a core of extensively fissured, collapsed terrain. Fissure abundance and distribution indicates that tectonism has been the dominant process controlling growth of the axial graben. Past magmatic activity is shown by the 200 m long chain of collapse basins between Crab Basin and Stonehenge, which may have held at least ~7500 m3 of lava. Assuming a flow thickness of 0.5 m, this amount of lava could cover over half the valley floor during a single volcanic event. At a local scale, MHF clusters vary in size, activity, and underlying geology. They range in size from 400-1600 m2 and consist of isolated chimneys and/or coalesced cockscomb arrays atop ramps of sulfide talus. In the northern part of the field, Cauldron, Twin Peaks, Faulty Towers, and Crab Basin are located near the western valley wall, bounded by basalt talus and a combination of collapsed sheet flows, intermixed lobate and sulfide, disrupted terrain, and isolated pillow ridges. The southern clusters, Cuchalainn and Stonehenge, are associated with collapse basins in the central valley

  14. Hydrothermal flow at Main Endeavour Field imaged and measured with Cable Operated Vent Imaging Sonar

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Bemis, K. G.; Xu, G.; Jackson, D. R.; Jones, C. D.

    2011-12-01

    Initial acoustic monitoring of hydrothermal flow in the Main Endeavour Field (MEF) captures the spatial distribution of diffuse and focused discharge and shows potential for flux determinations. Our Cabled Observatory Vent Imaging Sonar (COVIS) was connected to the NEPTUNE Canada Endeavour Observatory in September 2010. Using a customized Reson 7125 multi-beam sonar, COVIS acquired a 29 day time series of black smoker plume and associated diffuse hydrothermal flow from Grotto, a 30 m diameter vent cluster in the MEF, Juan de Fuca Ridge. Detection of the spatial patterns of diffuse flow utilizes phase decorrelation of the acoustic signal (200kHz) by buoyancy-driven turbulence (acoustic scintillation) to produce a time series of maps. Substantial fluctuation in the detected diffuse flow area (0.1 - 18 m^2) was observed over the 29 days of observation, although position remained stable. Acoustic imaging of focused flow (400 kHz) utilizes high volume backscatter (attributed to particles and turbulent sound speed fluctuations) to image in 3D the initial tens of meters of rise of buoyant plumes. Spectral analysis of bending inclination of a strong plume from multiple fast smokers on the NW end of Grotto (north tower) indicates that the dominant modes correspond with the ambient mixed semi-diurnal tide (based on current meter data at a mooring 2.9 km to the north and on a tidal model), with at least one secondary mode attributable to sub-inertial flow related to inflow to the axial valley. A weaker plume from several slower smokers is present on the NE end of Grotto. On first analysis, the bending inclination of the weaker plume appears to be affected by the stronger plume. Quantification of flow velocity and volume flux of plumes begins with measuring the Doppler phase shift through plume cross-sections beginning at 5 m above source vents where discharge merges. The volume flux measurements enable calculation of entrainment coefficients, which prior work on the same

  15. Aqueous Volatiles in Hydrothermal fluids from the Main Endeavour Vent Field: Temporal Variability Following Earthquake Activity

    NASA Astrophysics Data System (ADS)

    Seewald, J. S.; Cruse, A. M.; Saccocia, P. J.

    2001-12-01

    Volatile species play a critical role in a broad spectrum of physical, chemical, and biological processes associated with hydrothermal circulation at oceanic spreading centers. Earthquake activity at the Main Endeavour vent field, northern Juan de Fuca Ridge in June 1999 [1] provided and opportunity to assess factors that regulate the flux of volatile species from the oceanic crust to the water column following a rapid change in subsurface reaction zone conditions. High temperature vent fluids were collected in gas-tight samplers at the Main Endeavour field in September 1999, approximately four months after the earthquakes, and again in July 2000, and were analyzed for the abundance of aqueous volatile and non-volatile species. Measured concentrations of aqueous H2, H2S, and CO2 increased substantially in September 1999 relative to pre-earthquake values [2,3], and subsequently decreased in July 2000, while aqueous Cl concentrations initially decreased in 1999 and subsequently increased in 2000. Concentrations of Cl in all fluids were depleted relative to seawater values. Aqueous CH4 and NH3 concentrations decreased in both the 1999 and 2000 samples relative to pre- earthquake values. Variations in Cl concentration of Endeavour fluids reflect varying degrees of phase separation under near critical temperature and pressure conditions. Because volatile species efficiently partition into the vapor phase, variations in their abundance as a function of Cl concentration can be used to constrain conditions of phase separation and fluid-rock interaction. For example, concentrations of volatile species that are not readily incorporated into minerals (CH4 and NH3) correlated weakly with Cl suggesting phase separation was occurring under supercritical conditions after the earthquake activity. In contrast, compositional data for fluids prior to the earthquakes indicate a strong negative correlation between these species and Cl suggesting phase separation under subcritical

  16. Advanced Seismic Studies of the Endeavour Ridge: Understanding the Interplay among Magmatic, Hydrothermal, and Tectonic Processes at Mid-Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Arnoux, G. M.; VanderBeek, B. P.; Morgan, J. V.; Hooft, E. E. E.; Toomey, D. R.; Wilcock, W. S. D.; Warner, M.

    2014-12-01

    At mid-ocean ridges magmatic, hydrothermal, and tectonic processes are linked. Understanding their interactions requires mapping magmatic systems and tectonic structures, as well as their relationship to hydrothermal circulation. Three-dimensional seismic images of the crust can be used to infer the size, shape, and location of magma reservoirs, in addition to the structure of the thermal boundary layer that connects magmatic and hydrothermal processes. Travel time tomography has often been used to study these processes, however, the spatial resolution of travel time tomography is limited. Three-dimensional full waveform inversion (FWI) is a state-of-the art seismic method developed for use in the oil industry to obtain high-resolution models of the velocity structure. The primary advantage of FWI is that it has the potential to resolve subsurface structures on the order of half the seismic wavelength—a significant improvement on conventional travel time tomography. Here, we apply anisotropic FWI to data collected on the Endeavour segment of the Juan de Fuca Ridge. Starting models for anisotropic P-wave velocity were obtained by travel time tomography [Weekly et al., 2014]. During FWI, the isotropic velocity model is updated and anisotropy is held constant. We have recovered low-velocity zones approximately 2-3 km beneath the ridge axis that likely correspond to a segmented magma-rich body and are in concert with those previously resolved using multi-channel seismic reflection methods. The segmented crustal magma body underlies all five known high-temperature hydrothermal vent fields along the Endeavour segment. A high-velocity zone, shallower than the observed low-velocity zones, underlies the southernmost hydrothermal vent field. This may be indicative of waning hydrothermal activity in which minerals are crystallizing beneath the vent field. Our FWI study of the Endeavour Ridge will provide the most detailed three-dimensional images of the crustal structure to

  17. Age, Episodicity and Migration of Hydrothermal Activity within the Axial Valley, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Jamieson, J. W.; Hannington, M. D.; Kelley, D. S.; Clague, D. A.; Holden, J. F.; Tivey, M. K.; Delaney, J. R.

    2011-12-01

    Hydrothermal sulfide deposits record the history of high-temperature venting along the Endeavour Segment. Active venting is currently located within five discreet vent fields, with minor diffuse venting occurring between the fields. However, inactive and/or extinct sulfide structures are found throughout the entire axial valley of the ridge segment, suggesting that hydrothermal activity has been more vigorous in the past or focused venting has migrated with time. Here, we present age constraints from U-series dating of 44 sulfide samples collected by manned submersible from between the Mothra Field in the south to Sasquatch in the north. Samples are dated using 226Ra/Ba ratios from hydrothermal barite that precipitates along with the sulfide minerals. Most samples have been collected from within or near the active vent fields. Fifteen samples from the Main Endeavour Field (MEF) show a spectrum of ages from present to 2,430 years old, indicating that this field has been continuously active for at least ~2,400 years. MEF appears to be oldest currently active field. This minimum value for the age of hydrothermal activity also provides a minimum age of the axial valley itself. Ages from thirteen samples from the High-Rise Field indicate continuous venting for at least the past ~1,250 years. These age data are used in conjunction with age constraints of the volcanic flows to develop an integrated volcanic, hydrothermal and tectonic history of the Endeavour Segment. The total volume of hydrothermal sulfide within the axial valley, determined from high-resolution bathymetry, is used in conjunction with the age constraints of the sulfide material to determine the mass accumulation rates of sulfide along the Endeavour Segment. These data can be used to calibrate the efficiency of sulfide deposition from the hydrothermal vents, and provide a time-integrated history of heat, fluid and chemical fluxes at the ridge-segment scale. The comparison of time-integrated rates with

  18. Modeling mid-ocean ridge hydrothermal response to earthquakes, tides, and ocean currents: a case study at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Xu, G.; Bemis, K. G.

    2014-12-01

    Seafloor hydrothermal systems feature intricate interconnections among oceanic, geological, hydrothermal, 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 site of the NEPTUNE observatory, makes it a perfect place to study the response of a seafloor hydrothermal 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 hydrothermal 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 hydrothermal sub-seafloor circulation elucidates the potential mechanisms underlying hydrothermal response to local earthquakes. Second, we observe significant tidal oscillations in the venting temperature time series recorded by BARS and the acoustic imaging of hydrothermal plumes by COVIS, which is evidence for hydrothermal 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

  19. Microearthquakes beneath the Hydrothermal Vent Fields on the Endeavour Segment of the Juan de Fuca Ridge: Results from the Keck Seismic/Hydrothermal Observatory

    NASA Astrophysics Data System (ADS)

    Bowman, D.; Parker, J.; Wilcock, W.; Hooft, E.; Barclay, A.; Toomey, D.; McGill, P.; Stakes, D.; Schmidt, C.; Patel, H.

    2005-12-01

    The W.M. Keck Foundation is supporting the operation of a small seismic network in the vicinity of the hydrothermal vent fields on the central portion of the Endeavour Segment of the Juan de Fuca Ridge. This is part of a program to conduct prototype seafloor observatory experiments to monitor the relationships between episodic deformation, fluid venting and microbial productivity at oceanic plate boundaries. The Endeavour seismic network was installed in the summer of 2003 and comprises seven GEOSense three-component short-period corehole seismometers and one buried Guralp CMG-1T broadband seismometer. A preliminary analysis of the first year of data was undertaken as part of an undergraduate research apprenticeship class taught at the University of Washington's Friday Harbor Laboratories and additional analysis has since been completed by two of the apprentices and by two IRIS undergraduate interns. Over 12,000 earthquakes were located along the ridge-axis of the Endeavour, of which ~3,000 occur within or near the network and appear to be associated with the hydrothermal systems. The levels of seismicity are strongly correlated with the intensity of venting with particularly high rates of seismicity beneath the Main and High Rise Fields and substantially lower rates to the north beneath the relatively inactive Salty Dawg and Sasquatch fields. We have used both HYPOINVERSE and a grid search algorithm to investigate the distribution of focal depths assuming a variety of one-dimensional velocity models. The preliminary results show that the majority of earthquakes occur within a narrow depth range and may represent an intense zone of seismicity within a reaction overlying the axial magma chamber at ~2.5 km depth. However, the mean focal depth is strongly dependent on the relative weights assigned to the S arrivals. We infer from the inspection of residuals that no combination of the P- and S-wave velocity models we have so far investigated are fully consistent with

  20. Temporal and spatial variation in temperature experienced by macrofauna at Main Endeavour hydrothermal vent field

    NASA Astrophysics Data System (ADS)

    Lee, Raymond W.; Robert, Katleen; Matabos, Marjolaine; Bates, Amanda E.; Juniper, S. Kim

    2015-12-01

    A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10-12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays

  1. Dissolved Carbon Species in Diffuse and Focused Flow Hydrothermal Vents at the Main Endeavour Field, Northern Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Foustoukos, D. I.; Seyfried, W. E.; Ding, K.; Pester, N. J.

    2006-12-01

    The magmatic and tectonic event of 1999 had a significant impact on the chemical composition of vent fluids issuing from the Main Endeavour Field (MEF), Juan de Fuca Ridge. Here, we report dissolved concentrations of H2, CO2, CO and C1-C3 alkanes measured in low and high-temperature hydrothermal fluids collected in August 2005 during an RV Atlantis/DSV Alvin expedition at MEF. In comparison with time series data, temperatures of the 2005 vent fluids were slightly lower than those recorded in the aftermaths of the tectonic event of 1999. The possible cooling of the hydrothermal subseafloor reaction zone is consistent with the observed increase in dissolved Cl to pre-1999 values. Converging compositional trends to pre-1999 conditions are also suggested for dissolved CO2 concentrations (~20 mmol/kg) in Puffer, Sully, Bastille and S&M vent fluids. In these focused flow and high-temperature vent fluids, dissolved CO2 is in thermodynamic equilibrium with CO(aq). The systematics of organic species in diffuse flow fluids, however, appears to be closely related to processes occurring within the near-seafloor environment. For example, excess CO(aq) observed in the diffuse flow fluids at Easter Island is attributed to sluggish CO- CO2(aq) equilibria at low temperatures, suggesting hydrothermal circulation of short-residence times. Short-lived hydrothermal circulation is further supported by the nearly identical C1/(C2+C3) ratios between focused and diffuse flow fluids. Furthermore, alkane distribution in the MEF diffuse flow fluids suggests direct mixing between seawater and hydrothermal fluid with minimal biological inputs, in contrast with the greater effect of microbial methanogenesis proposed in other ridge-crest hydrothermal environments. Thus, the coupling of CO2(aq)-CO(aq) redox equilibrium with dissolved carbon species in low- temperature vent fluids could provide a better understanding of the effect of subsurface microbial communities upon the composition of mid

  2. METEORIC-HYDROTHERMAL SYSTEMS.

    USGS Publications Warehouse

    Criss, Robert E.; Taylor, Hugh P.

    1986-01-01

    This paper summarizes the salient characteristics of meteoric-hydrothermal systems, emphasing the isotopic systematics. Discussions of permeable-medium fluid dynamics and the geology and geochemistry of modern geothermal systems are also provided, because they are essential to any understanding of hydrothermal circulation. The main focus of the paper is on regions of ancient meteoric-hydrothermal activity, which give us information about the presently inaccessible, deep-level parts of modern geothermal systems. It is shown oxygen and hydrogen isotopes provide a powerful method to discover and map fossil hydrothermal systems and to investigate diverse associated aspects of rock alteration and ore deposition.

  3. Rhythms and community dynamics of a hydrothermal tubeworm assemblage at main endeavour field - a multidisciplinary deep-sea observatory approach.

    PubMed

    Cuvelier, Daphne; Legendre, Pierre; Laes, Agathe; Sarradin, Pierre-Marie; Sarrazin, Jozée

    2014-01-01

    The NEPTUNE cabled observatory network hosts an ecological module called TEMPO-mini that focuses on hydrothermal vent ecology and time series, granting us real-time access to data originating from the deep sea. In 2011-2012, during TEMPO-mini's first deployment on the NEPTUNE network, the module recorded high-resolution imagery, temperature, iron (Fe) and oxygen on a hydrothermal assemblage at 2186 m depth at Main Endeavour Field (North East Pacific). 23 days of continuous imagery were analysed with an hourly frequency. Community dynamics were analysed in detail for Ridgeia piscesae tubeworms, Polynoidae, Pycnogonida and Buccinidae, documenting faunal variations, natural change and biotic interactions in the filmed tubeworm assemblage as well as links with the local environment. Semi-diurnal and diurnal periods were identified both in fauna and environment, revealing the influence of tidal cycles. Species interactions were described and distribution patterns were indicative of possible microhabitat preference. The importance of high-resolution frequencies (<1 h) to fully comprehend rhythms in fauna and environment was emphasised, as well as the need for the development of automated or semi-automated imagery analysis tools.

  4. Abundance and Distribution of Hydrothermal Chimneys and Mounds on the Endeavour Ridge Determined by 1-m Resolution AUV Multibeam Mapping Surveys

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Caress, D. W.; Thomas, H.; Thompson, D.; Calarco, M.; Holden, J.; Butterfield, D.

    2008-12-01

    High-resolution seafloor mapping surveys were conducted on the Endeavour Ridge using the MBARI AUV D. Allan B. during R/V Atlantis cruise AT15-36. The four surveys had a combined bottom time of about 46 hours, collected data along 238 km of track, and mapped roughly 35 km2 with 200 kHz multibeam bathymetry and 100 kHz chirp sidescan. The bathymetry data have a 1-m lateral resolution and 0.1-m vertical precision. The surveys focused on the axial valley from 48°0.0' to 47°53.1'N or from 4.3 km south of the Mothra vent field to 0.5 km north of the Sasquatch vent field. We also mapped the western flank of the ridge between the Mothra and High Rise vent fields. The AUV is navigated using an inertial navigation system (INS) aided by Doppler Velocity Log (DVL) estimates of velocity over bottom. For these deep-water surveys, the initial AUV location derives from USBL fixes communicated to the vehicle by acoustic modem. Cross-correlation of bathymetric features in overlapping or crossing swaths allowed solution for an optimal navigation model that is internally self-consistent and accurate to the bathymetric resolution of 1 m. The surveys imaged over 800 individual chimney or hydrothermal mound structures, roughly 20% from the five main vent fields. Chimney structures occur along the entire axial valley but are less common near the southern end of the survey. In addition, chimneys occur along faults and on fault slivers bounding the deepest part of the axial valley to the east and west and to the crest on the west side of the axis. The tallest structure, at 28 m, was located at the High Rise field just south of Godzilla vent. Many of the chimneys previously mapped at Mothra were below our detection levels or combined in single pixels, so the number of chimneys identified is clearly a minimum number with many smaller deposits and chimneys excluded from our count. A hydrothermal mound 135 m in diameter and 60 m tall occurs off-axis about 2 km SSW of the Mothra vent field

  5. Comparison of Magma Residence, Magma Ascent and Magma-Hydrothermal Interaction at EPR 9°N and Endeavour Segment

    NASA Astrophysics Data System (ADS)

    Michael, P. J.; Gill, J. B.; Ramos, F. C.

    2010-12-01

    the axis, as seen in the 2005-6 flow where CO2 decreases and bubble size increases away from the eruptive vent [3]. CO2 contents of Endeavour glasses are lower in general than EPR 9°N glasses despite their deeper AMC [4], suggesting that they had more time to exsolve. Highest values are lower than the CO2 content corresponding to the AMC roof, while lowest values are in equilibrium with their seafloor depths. Either the lavas took longer to ascend from depth or they flowed longer at the surface, or both. Young off-axis lavas on Endeavour have low CO2 that cannot be ascribed to post-eruptive flow away from the axis, because they occur outside an enclosed axial valley. The comparison of the CO2 and Cl data from the two ridges does not support a simple interpretation in which fast-rising magmas are less likely to interact with hydrothermally altered crust. [1] leRoux et al. (2003) EPSL 251, 209-231. [2] Michael & Schilling (1989) GCA 53, 3131-3143. [3] Michael et al. (2008) Fall AGU #V21B-2106. [4] vanArk et al., (2007) JGR 112, doi:10.1029/2005JB004210;

  6. Rapid variations in fluid chemistry constrain hydrothermal phase separation at the Main Endeavour Field

    NASA Astrophysics Data System (ADS)

    Love, Brooke; Lilley, Marvin; Butterfield, David; Olson, Eric; Larson, Benjamin

    2017-02-01

    Previous work at the Main Endeavour Field (MEF) has shown that chloride concentration in high-temperature vent fluids has not exceeded 510 mmol/kg (94% of seawater), which is consistent with brine condensation and loss at depth, followed by upward flow of a vapor phase toward the seafloor. Magmatic and seismic events have been shown to affect fluid temperature and composition and these effects help narrow the possibilities for sub-surface processes. However, chloride-temperature data alone are insufficient to determine details of phase separation in the upflow zone. Here we use variation in chloride and gas content in a set of fluid samples collected over several days from one sulfide chimney structure in the MEF to constrain processes of mixing and phase separation. The combination of gas (primarily magmatic CO2 and seawater-derived Ar) and chloride data, indicate that neither variation in the amount of brine lost, nor mixing of the vapor phase produced at depth with variable quantities of (i) brine or (ii) altered gas rich seawater that has not undergone phase separation, can explain the co-variation of gas and chloride content. The gas-chloride data require additional phase separation of the ascending vapor-like fluid. Mixing and gas partitioning calculations show that near-critical temperature and pressure conditions can produce the fluid compositions observed at Sully vent as a vapor-liquid conjugate pair or as vapor-liquid pair with some remixing, and that the gas partition coefficients implied agree with theoretically predicted values.Plain Language SummaryWhen the chemistry of fluids from deep sea hot springs changes over a short time span, it allows us to narrow down the conditions and processes that created those fluids. This gives us a better idea what is happening under the seafloor where the water is interacting with hot rocks and minerals, boiling, and taking on the character it will have when it emerges at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.minsocam.org/MSA/AmMin/TOC/2016/index.html?issue_number=02','USGSPUBS'); return false;" href="http://www.minsocam.org/MSA/AmMin/TOC/2016/index.html?issue_number=02"><span>The Lassen <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ingebritsen, Steven E.; Bergfeld, Deborah; Clor, Laura; Evans, William C.</p> <p>2016-01-01</p> <p>The active Lassen <span class="hlt">hydrothermal</span> <span class="hlt">system</span> includes a central vapor-dominated zone or zones beneath the Lassen highlands underlain by ~240 °C high-chloride waters that discharge at lower elevations. It is the best-exposed and largest <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in the Cascade Range, discharging 41 ± 10 kg/s of steam (~115 MW) and 23 ± 2 kg/s of high-chloride waters (~27 MW). The Lassen <span class="hlt">system</span> accounts for a full 1/3 of the total high-temperature <span class="hlt">hydrothermal</span> heat discharge in the U.S. Cascades (140/400 MW). <span class="hlt">Hydrothermal</span> heat discharge of ~140 MW can be supported by crystallization and cooling of silicic magma at a rate of ~2400 km3/Ma, and the ongoing rates of heat and magmatic CO2 discharge are broadly consistent with a petrologic model for basalt-driven magmatic evolution. The clustering of observed seismicity at ~4–5 km depth may define zones of thermal cracking where the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> mines heat from near-plastic rock. If so, the combined areal extent of the primary heat-transfer zones is ~5 km2, the average conductive heat flux over that area is >25 W/m2, and the conductive-boundary length <50 m. Observational records of <span class="hlt">hydrothermal</span> discharge are likely too short to document long-term transients, whether they are intrinsic to the <span class="hlt">system</span> or owe to various geologic events such as the eruption of Lassen Peak at 27 ka, deglaciation beginning ~18 ka, the eruptions of Chaos Crags at 1.1 ka, or the minor 1914–1917 eruption at the summit of Lassen Peak. However, there is a rich record of intermittent <span class="hlt">hydrothermal</span> measurement over the past several decades and more-frequent measurement 2009–present. These data reveal sensitivity to climate and weather conditions, seasonal variability that owes to interaction with the shallow hydrologic <span class="hlt">system</span>, and a transient 1.5- to twofold increase in high-chloride discharge in response to an earthquake swarm in mid-November 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B13C0479H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B13C0479H"><span>Microbial and Mineral Descriptions of the Interior Habitable Zones of Active <span class="hlt">Hydrothermal</span> Chimneys from the <span class="hlt">Endeavour</span> 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>Holden, J. F.; Lin, T.; Ver Eecke, H. C.; Breves, E.; Dyar, M. D.; Jamieson, J. W.; Hannington, M. D.; Butterfield, D. A.; Bishop, J. L.; Lane, M. D.</p> <p>2013-12-01</p> <p> hyperthermophilic iron reducers in this sample were 1,740 and 10 cells/gram (dry weight) of material from scrapings of the outer surface and the soft, marcasite-sphalerite-rich interior region, respectively. Two hyperthermophilic iron reducers, Hyperthermus sp. Ro04 and Pyrodictium sp. Su06, were isolated from other active <span class="hlt">hydrothermal</span> chimneys on the <span class="hlt">Endeavour</span> Segment. Strain Ro04 is a neutrophilic (pHopt 7-8) heterotroph while strain Su06 is a mildly acidophilic (pHopt 5), hydrogenotrophic autotroph. Mössbauer spectroscopy of the iron oxides before and after growth demonstrated that both organisms form nanophase (<12 nm) magnetite [Fe3O4] from ferrihydrite [Fe(OH)3] with no detectable mineral intermediates. Both organisms grew optimally at 90-92°C with growth yields of 0.5-5×1012 cells/mol Fe2+ and Fe2+ production rates between 0.03-0.54 pmol Fe2+/cell/h. They produced up to 40 mM Fe2+ in a growth-dependent manner while all abiotic controls produced < 3 mM Fe2+. Electron micrographs show that the cells form aggregates with iron oxide particles during growth. Hyperthermophilic iron reducers may be common in mildly reducing, iron-rich <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> where iron oxides are formed at hyperthermophile growth temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17..300L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17..300L"><span>Linkages between mineralogy, fluid chemistry, and microbial communities within <span class="hlt">hydrothermal</span> chimneys from the <span class="hlt">Endeavour</span> 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>Lin, T. J.; Ver Eecke, H. C.; Breves, E. A.; Dyar, M. D.; Jamieson, J. W.; Hannington, M. D.; Dahle, H.; Bishop, J. L.; Lane, M. D.; Butterfield, D. A.; Kelley, D. S.; Lilley, M. D.; Baross, J. A.; Holden, J. F.</p> <p>2016-02-01</p> <p>Rock and fluid samples were collected from three <span class="hlt">hydrothermal</span> chimneys at the <span class="hlt">Endeavour</span> Segment, Juan de Fuca Ridge to evaluate linkages among mineralogy, fluid chemistry, and microbial community composition within the chimneys. Mössbauer, midinfrared thermal emission, and visible-near infrared spectroscopies were utilized for the first time to characterize vent mineralogy, in addition to thin-section petrography, X-ray diffraction, and elemental analyses. A 282°C venting chimney from the Bastille edifice was composed primarily of sulfide minerals such as chalcopyrite, marcasite, and sphalerite. In contrast, samples from a 300°C venting chimney from the Dante edifice and a 321°C venting chimney from the Hot Harold edifice contained a high abundance of the sulfate mineral anhydrite. Geochemical modeling of mixed vent fluids suggested the oxic-anoxic transition zone was above 100°C at all three vents, and that the thermodynamic energy available for autotrophic microbial redox reactions favored aerobic sulfide and methane oxidation. As predicted, microbes within the Dante and Hot Harold chimneys were most closely related to mesophilic and thermophilic aerobes of the Betaproteobacteria and Gammaproteobacteria and sulfide-oxidizing autotrophic Epsilonproteobacteria. However, most of the microbes within the Bastille chimney were most closely related to mesophilic and thermophilic anaerobes of the Deltaproteobacteria, especially sulfate reducers, and anaerobic hyperthermophilic archaea. The predominance of anaerobes in the Bastille chimney indicated that other environmental factors promote anoxic conditions. Possibilities include the maturity or fluid flow characteristics of the chimney, abiotic Fe2+ and S2- oxidation in the vent fluids, or O2 depletion by aerobic respiration on the chimney outer wall.</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>Cody <span class="hlt">hydrothermal</span> <span class="hlt">system</span></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 <span class="hlt">system</span>. That <span class="hlt">system</span> 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> <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A1996H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A1996H"><span>Monitoring Change on <span class="hlt">Hydrothermal</span> Edifices by Photogrammetric Time Series: Case Studies from the <span class="hlt">Endeavour</span> 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>Heesemann, M.; Kwasnitschka, T.; Kelley, D. S.; Mihaly, S. F.</p> <p>2015-12-01</p> <p>High-resolution photogrammetric surveys derived from ROV or AUV imagery yield seafloor geometry at centimeter resolution with full color texture while modeling overhangs and crevasses, generating vastly more detailed terrain models compared to most acoustic methods. The models furthermore serve as geographic reference frames for localized studies. Repetitive surveys consequently facilitate the precise, quantitative study of edifice buildup and erosion as well as the development of the biological habitat. We compare data gathered by the Ocean Networks Canada maintenance cruises with earlier surveys at two sites (Mothra, Main <span class="hlt">Endeavour</span> Field) along the <span class="hlt">Endeavour</span> Segment of the Juan de Fuca Ridge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.V31D0661R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.V31D0661R"><span>En Echelon <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ryan, M. P.; Carr, P. M.; Daniels, D. L.; Sutphin, D. M.</p> <p>2005-12-01</p> <p>En echelon <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> develop within the porous rocks that surround, in three-dimensions, their distinctive plan-form and cross-sectional basaltic intrusion geometry. Examples that span several (self-similar) spatial scales include the en echelon off-set area of the East Rift Zone of Kilauea Volcano, Hawaii; the Northeast Rift Zone of Mauna Loa Volcano; the intrusive-eruptive fissures of the Krafla Central Volcano, Northeast Iceland; the ensemble of the three Icelandic central volcanoes Theistarekir-Krafla-Fremrinamur; major segments of the East Pacific Rise and the Mid-Atlantic Ridge; and several paleo-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of the Mesozoic basins of eastern North America, including the Culpeper Basin. An en echelon <span class="hlt">hydrothermal</span> <span class="hlt">system</span> comprises two or more en echelon--arranged magma-filled fractures enclosed in a fluid-saturated porous matrix. Blocks of country rock between individual offset fracture segments are similarly porous and fluid-saturated. In 3-D, the <span class="hlt">system</span> resembles the fan blades of a turbine rotor, with blades (dikes) emanating from a deep "master" fracture and turning smoothly in response to the local variations in the least compressive regional stress component. The primary geometric, hydrologic and thermal attributes of the <span class="hlt">system</span> (on a horizontal plane) include dike thickness, dike-to-dike offset and overlap, the (initial) intrusion temperature, duration of magma flow, dike widths and lengths, the mean seepage velocity of regional subsurface aqueous fluid flow, and the mean flow azimuth in relationship to the plan-form geometry of the en echelon array. Finite element single phase models in horizontal cross-section have been developed for dike widths of 100 m, dike lengths of 1,500 m, overlaps of 500 m, dike-to-dike offsets of 500 m, intrusion temperatures of 1,200 C, horizontal seepage fluxes imposed at the sides of ~ 1,000 g cm-2 yr-1, and a matrix permeability of 10-14 m2. The regional flow field has been parameterized in dike</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T31A0488D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T31A0488D"><span>In-situ Chemistry of <span class="hlt">Hydrothermal</span> Fluids from Black Smokers in Main <span class="hlt">Endeavour</span> Field, 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>Ding, K.; Seyfried, W. E.; Zhang, Z.; Foustoukos, D.; Pester, N. J.</p> <p>2005-12-01</p> <p>After an off-axis earthquake swarm in 1999, dramatic changes were observed in vent fluids of Main <span class="hlt">Endeavour</span> Field, Juan de Fuca Ridge. Three month latter, we also recorded this sudden variation using a high temperature in-situ chemical sensor. The results at that time indicated some of the vent temperatures as high as 374°C. This change was also characterized by relatively high in-situ pH, high dissolved H2, and H2S concentrations in the fluids that were in excess of 5, 0.7 mmol/kg and 20 mmol/kg respectively. In order to further track time dependent changes over the past 6 years, we revisited Main <span class="hlt">Endeavour</span> Field during the recent AT 11-31 cruise in Aug.~Sept. 2005. The high temperature chemical sensor was again used on selected dives with DSV Alvin to conduct in-situ measurements of pH, dissolved H2 and H2S concentrations along with temperatures. The data were obtained in a real time mode of 3 seconds per-reading from a series of measurements at high temperature conditions in the depth of 2200 m. Conventional gas-tight samples were also collected for verification and further study. In this study, Puffer, Sully and Bastille black smoker vent sites were specifically investigated owing to the high fluid temperatures that characterize these vents in comparison with other vents in the area. The measured temperatures for these vents were 362°C, 358°C, and 361°C respectively, which were generally about 20~30°C higher than the others currently in the area, but approximately 10°C lower than the highest temperatures measured in the aftermath of the 1999 seismic-magmatic event. Although the drops in vent temperatures were not substantial, the measured in-situ chemistry showed large departures from previous reported data. The in-situ pH values in these vents ranged from 4.43 to 4.89, in comparison with values above 5 in 1999. This difference may be linked directly to the decrease in temperature. The measured in-situ dissolved H2 and H2S concentrations were 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4014580','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4014580"><span>Rhythms and Community Dynamics of a <span class="hlt">Hydrothermal</span> Tubeworm Assemblage at Main <span class="hlt">Endeavour</span> Field – A Multidisciplinary Deep-Sea Observatory Approach</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cuvelier, Daphne; Legendre, Pierre; Laes, Agathe; Sarradin, Pierre-Marie; Sarrazin, Jozée</p> <p>2014-01-01</p> <p>The NEPTUNE cabled observatory network hosts an ecological module called TEMPO-mini that focuses on <span class="hlt">hydrothermal</span> vent ecology and time series, granting us real-time access to data originating from the deep sea. In 2011–2012, during TEMPO-mini’s first deployment on the NEPTUNE network, the module recorded high-resolution imagery, temperature, iron (Fe) and oxygen on a <span class="hlt">hydrothermal</span> assemblage at 2186 m depth at Main <span class="hlt">Endeavour</span> Field (North East Pacific). 23 days of continuous imagery were analysed with an hourly frequency. Community dynamics were analysed in detail for Ridgeia piscesae tubeworms, Polynoidae, Pycnogonida and Buccinidae, documenting faunal variations, natural change and biotic interactions in the filmed tubeworm assemblage as well as links with the local environment. Semi-diurnal and diurnal periods were identified both in fauna and environment, revealing the influence of tidal cycles. Species interactions were described and distribution patterns were indicative of possible microhabitat preference. The importance of high-resolution frequencies (<1 h) to fully comprehend rhythms in fauna and environment was emphasised, as well as the need for the development of automated or semi-automated imagery analysis tools. PMID:24810603</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B12A0752V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B12A0752V"><span>Seismic Structure of the <span class="hlt">Endeavour</span> Segment, Juan de Fuca Ridge: Correlations of Crustal Magma Chamber Properties With Seismicity, Faulting, and <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>van Ark, E. M.; Detrick, R. S.; Canales, J. P.; Carbotte, S. M.; Diebold, J. B.; Harding, A.; Kent, G.; Nedimovic, M. R.; Wilcock, W. S.</p> <p>2003-12-01</p> <p>Multichannel seismic reflection data collected in July 2002 at the RIDGE2000 Integrated Studies Site at the <span class="hlt">Endeavour</span> segment, Juan de Fuca Ridge show a high-amplitude, mid-crustal reflector underlying all of the known <span class="hlt">hydrothermal</span> vent fields at this segment. This reflector, which has been identified with a crustal magma body [Detrick et al., 2002], is found at a two-way travel time of 0.85-1.5 s (1.9-4.0 km) below the seafloor and extends approximately 25 km along axis although it is only 1-2 km wide on the cross-axis lines. The reflector is shallowest (2.5 km depth on the along-axis line) beneath the central, elevated part of the <span class="hlt">Endeavour</span> segment and deepens toward the segment ends, with a maximum depth of 4 km. The cross axis lines show the mid-crustal reflector dipping from 9 to 50? to the east with the shallowest depths under the ridge axis and greater depths under the eastern flank of the ridge. The amplitude-offset behavior of this mid-crustal axial reflector is consistent with a negative impedance contrast, indicating the presence of melt or a crystallizing mush. We have constructed partial offset stacks at 2-3 km offset to examine the variation of melt-mush content of the axial magma chamber along axis. We see a decrease in P-wave amplitudes with increasing offset for the mid-crustal reflector beneath the Mothra and Main <span class="hlt">Endeavour</span> vent fields and between the Salty Dawg and Sasquatch vent fields, indicating the presence of a melt-rich body. Beneath the High Rise, Salty Dawg, and Sasquatch vent fields P-wave amplitudes vary little with offset suggesting the presence of a more mush-rich magma chamber. Hypocenters of well-located microseismicity in this region [Wilcock et al., 2002] have been projected onto the along-axis and cross-axis seismic lines, revealing that most axial earthquakes are concentrated in a depth range of 1.5 - 2.7 km, just above the axial magma chamber. In general, seismicity is distributed diffusely within this zone indicating thermal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70170389','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70170389"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> and volcano geochemistry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fournier, R.O.</p> <p>2007-01-01</p> <p>The upward intrusion of magma from deeper to shallower levels beneath volcanoes obviously plays an important role in their surface deformation. This chapter will examine less obvious roles that <span class="hlt">hydrothermal</span> processes might play in volcanic deformation. Emphasis will be placed on the effect that the transition from brittle to plastic behavior of rocks is likely to have on magma degassing and <span class="hlt">hydrothermal</span> processes, and on the likely chemical variations in brine and gas compositions that occur as a result of movement of aqueous-rich fluids from plastic into brittle rock at different depths. To a great extent, the model of <span class="hlt">hydrothermal</span> processes in sub-volcanic <span class="hlt">systems</span> that is presented here is inferential, based in part on information obtained from deep drilling for geothermal resources, and in part on the study of ore deposits that are thought to have formed in volcanic and shallow plutonic environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23401293','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23401293"><span>Free-living bacterial communities associated with tubeworm (Ridgeia piscesae) aggregations in contrasting diffuse flow <span class="hlt">hydrothermal</span> vent habitats at the Main <span class="hlt">Endeavour</span> Field, Juan de Fuca Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Forget, Nathalie L; Kim Juniper, S</p> <p>2013-04-01</p> <p>We systematically studied free-living bacterial diversity within aggregations of the vestimentiferan tubeworm Ridgeia piscesae sampled from two contrasting flow regimes (High Flow and Low Flow) in the <span class="hlt">Endeavour</span> <span class="hlt">Hydrothermal</span> Vents Marine Protected Area (MPA) on the Juan de Fuca Ridge (Northeast Pacific). Eight samples of particulate detritus were recovered from paired tubeworm grabs from four vent sites. Most sequences (454 tag and Sanger methods) were affiliated to the Epsilonproteobacteria, and the sulfur-oxidizing genus Sulfurovum was dominant in all samples. Gammaproteobacteria were also detected, mainly in Low Flow sequence libraries, and were affiliated with known methanotrophs and decomposers. The cooccurrence of sulfur reducers from the Deltaproteobacteria and the Epsilonproteobacteria suggests internal sulfur cycling within these habitats. Other phyla detected included Bacteroidetes, Actinobacteria, Chloroflexi, Firmicutes, Planctomycetes, Verrucomicrobia, and Deinococcus-Thermus. Statistically significant relationships between sequence library composition and habitat type suggest a predictable pattern for High Flow and Low Flow environments. Most sequences significantly more represented in High Flow libraries were related to sulfur and hydrogen oxidizers, while mainly heterotrophic groups were more represented in Low Flow libraries. Differences in temperature, available energy for metabolism, and stability between High Flow and Low Flow habitats potentially explain their distinct bacterial communities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3633350','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3633350"><span>Free-living bacterial communities associated with tubeworm (Ridgeia piscesae) aggregations in contrasting diffuse flow <span class="hlt">hydrothermal</span> vent habitats at the Main <span class="hlt">Endeavour</span> Field, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Forget, Nathalie L; Kim Juniper, S</p> <p>2013-01-01</p> <p>We systematically studied free-living bacterial diversity within aggregations of the vestimentiferan tubeworm Ridgeia piscesae sampled from two contrasting flow regimes (High Flow and Low Flow) in the <span class="hlt">Endeavour</span> <span class="hlt">Hydrothermal</span> Vents Marine Protected Area (MPA) on the Juan de Fuca Ridge (Northeast Pacific). Eight samples of particulate detritus were recovered from paired tubeworm grabs from four vent sites. Most sequences (454 tag and Sanger methods) were affiliated to the Epsilonproteobacteria, and the sulfur-oxidizing genus Sulfurovum was dominant in all samples. Gammaproteobacteria were also detected, mainly in Low Flow sequence libraries, and were affiliated with known methanotrophs and decomposers. The cooccurrence of sulfur reducers from the Deltaproteobacteria and the Epsilonproteobacteria suggests internal sulfur cycling within these habitats. Other phyla detected included Bacteroidetes, Actinobacteria, Chloroflexi, Firmicutes, Planctomycetes, Verrucomicrobia, and Deinococcus–Thermus. Statistically significant relationships between sequence library composition and habitat type suggest a predictable pattern for High Flow and Low Flow environments. Most sequences significantly more represented in High Flow libraries were related to sulfur and hydrogen oxidizers, while mainly heterotrophic groups were more represented in Low Flow libraries. Differences in temperature, available energy for metabolism, and stability between High Flow and Low Flow habitats potentially explain their distinct bacterial communities. PMID:23401293</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><span class="hlt">Hydrothermal</span> processes above the Yellowstone magma chamber: Large <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and large <span class="hlt">hydrothermal</span> explosions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, L.A.; Shanks, W.C. Pat; Pierce, K.L.</p> <p>2009-01-01</p> <p> and vein-fi lling; and (5) areal dimensions of many large <span class="hlt">hydrothermal</span> explosion craters in Yellowstone are similar to those of its active geyser basins and thermal areas. For Yellowstone, our knowledge of <span class="hlt">hydrothermal</span> craters and ejecta is generally limited to after the Yellowstone Plateau emerged from beneath a late Pleistocene icecap that was roughly a kilometer thick. Large <span class="hlt">hydrothermal</span> explosions may have occurred earlier as indicated by multiple episodes of cementation and brecciation commonly observed in <span class="hlt">hydrothermal</span> ejecta clasts. Critical components for large, explosive <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> include a watersaturated <span class="hlt">system</span> at or near boiling temperatures and an interconnected <span class="hlt">system</span> of well-developed joints and fractures along which <span class="hlt">hydrothermal</span> fluids flow. Active deformation of the Yellowstone caldera, active faulting and moderate local seismicity, high heat flow, rapid changes in climate, and regional stresses are factors that have strong infl uences on the type of <span class="hlt">hydrothermal</span> <span class="hlt">system</span> developed. Ascending <span class="hlt">hydrothermal</span> fluids flow along fractures that have developed in response to active caldera deformation and along edges of low-permeability rhyolitic lava flows. Alteration of the area affected, self-sealing leading to development of a caprock for the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, and dissolution of silica-rich rocks are additional factors that may constrain the distribution and development of <span class="hlt">hydrothermal</span> fields. A partial lowpermeability layer that acts as a cap to the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> may produce some over-pressurization, thought to be small in most <span class="hlt">systems</span>. Any abrupt drop in pressure initiates steam fl ashing and is rapidly transmitted through interconnected fractures that result in a series of multiple large-scale explosions contributing to the excavation of a larger explosion crater. Similarities between the size and dimensions of large <span class="hlt">hydrothermal</span> explosion craters and thermal fields in Yellowstone may indicate that catastrophic events which result in l</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990JGR....9519235K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990JGR....9519235K"><span>Spatial and temporal evolution of magmatic <span class="hlt">systems</span> beneath the <span class="hlt">endeavour</span> segment, Juan de Fuca Ridge: Tectonic and petrologic constraints</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karsten, Jill L.; Delaney, John R.; Rhodes, J. Michael; Liias, Raimo A.</p> <p>1990-11-01</p> <p>Major and trace element data for a suite of lavas from fifty-six dredges and ALVEN dives on the ridge axis and adjacent abyssal hills have been used to investigate the geometry and evolution of magmatic <span class="hlt">systems</span> beneath the <span class="hlt">Endeavour</span> Segment, Juan de Fuca Ridge. The morphology of the <span class="hlt">Endeavour</span> Segment between the northward propagating Cobb Offset and the recently formed (<0.2 m.y.) <span class="hlt">Endeavour</span> Offset is dominated by a shallow, rifted, elongate crestal volcano (<span class="hlt">Endeavour</span> Ridge) that deepens along-strike into a broad, deep basin at each offset. A set of ridges, interpreted to be previous crestal volcanoes rifted apart by spreading, flank the <span class="hlt">Endeavour</span> Ridge and chronicle the "dueling" propagator history of the Cobb Offset The tectonic evidence strongly suggests that a large portion of the <span class="hlt">Endeavour</span> Segment may be a failing rift segment at this time. Lavas from the current axis of the <span class="hlt">Endeavour</span> Segment are moderately fractionated (MgO: 6-8.5 wt %) and have generally higher SiO2, Al2O3, Na2O, and K2O, and lower FeO* man lavas from south of the Cobb Offset (SOCO lavas). Incompatible trace element abundances and ratios indicate the <span class="hlt">Endeavour</span> lavas are primarily enriched E-MORBs and T-MORBs (e.g., Zr/Nb: 7-24; Zr/Y: 2.5-5.9; and Ba/TiO2: 6-64), in contrast with the SOCO lavas, which are more depleted in character. Thus, the 30-km wide Cobb Offset appears to mark a major geochemical boundary beneath the Juan de Fuca Ridge. In contrast with the <span class="hlt">Endeavour</span> Segment axial lavas, samples from adjacent abyssal hills are more similar to the SOCO lavas in their major and trace element characteristics. These observations suggest that the parental magmas of the <span class="hlt">Endeavour</span> Segment exhibit temporal variability, with more enriched material arriving only recently beneath the ridge axis. Pronounced compositional variability is observed at small spatial scales within the <span class="hlt">Endeavour</span> Segment axial lavas, which does not correlate with axial morphology. This variability is interpreted to reflect</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_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</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><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_2 --> <div id="page_3" 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_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</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="41"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA11837&hterms=annotations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dannotations','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA11837&hterms=annotations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dannotations"><span><span class="hlt">Endeavour</span> Crater in Context</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2009-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/> The largest crater in this mosaic of images taken by the Context Camera on NASA's Mars Reconnaissance Orbiter is <span class="hlt">Endeavour</span> Crater, which is 22 kilometers (14 miles) in diameter. <p/> The team operating NASA's Mars Exploration Rover Opportunity in the Meridiani Planum region of Mars chose to drive the rover toward <span class="hlt">Endeavour</span> after Opportunity ascended out of smaller Victoria Crater in August 2008. <p/> Opportunity caught its first glimpse of <span class="hlt">Endeavour</span>'s rim on March 7, 2008, during the 1,820th Martian day, or sol, of the rover's mission on Mars. The rover was about 12 kilometers (7 miles) from the closest point of the crater. <p/> Annotations on Figure 1 show vectors from Opportunity's position on that date toward the portions of the rim seen in images that Opportunity's panoramic camera (Pancam) took from the Sol 1820 location. In addition to three portions of <span class="hlt">Endeavour</span>'s rim, the rim of a smaller, more distant crater, Iazu, appears faintly on the horizon in the Pancam images. <p/> NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space <span class="hlt">Systems</span>, Denver, is the prime contractor for the project and built the spacecraft. Malin Space Science <span class="hlt">Systems</span>, San Diego, provided and operates the Context Camera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS41C1835Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS41C1835Y"><span>Boron isotope systematics of <span class="hlt">hydrothermal</span> fluids from submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamaoka, K.; Hong, E.; Ishikawa, T.; Gamo, T.; Kawahata, H.</p> <p>2013-12-01</p> <p>Boron is highly mobile in submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and useful to trace the process of water-rock reaction. In this study, we measured the boron content and isotopic composition of vent fluids collected from arc-backarc <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the western Pacific. In sediment-starved <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> (Manus Basin, Suiyo Seamount, and Mariana Trough), the boron content and isotopic composition of vent fluids are dependent on type of host rock. The end member fluids from MORB-like basalt-hosted Vienna Woods in the Manus Basin showed low boron content and high δ11B value (0.53 mM, 29.8‰), while dacite-hosted PACMANUS and the Suiyo Seamount showed high boron contents and low δ11B values (1.45 and 1.52 mM, 13.6 and 18.5‰, respectively). The Alice Springs and Forecast Vent field in the Mariana Trough showed values intermediate between them (0.72 and 0.63 mM, 19.9 and 24.0‰, respectively), reflecting reaction of seawater and basalt influenced by slab material. In phase separated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> (North Fiji Basin), boron content and isotopic composition of vent fluids (0.44-0.56 mM, 34.5-35.9‰) were similar to those in the Vienna Woods. Considering little fractionation of boron and boron isotope during phase separation demonstrated by the previous experimental studies, it is suggested that the host rock in the North Fiji Basin is MORB-like basalt. In sediment-hosted <span class="hlt">hydrothermal</span> <span class="hlt">system</span> (Okinawa Trough), the reaction with boron-enriched sediment following seawater-rock reaction resulted in significantly high boron contents and low δ11B values of vent fluids (4.4-5.9 mM, 1.5-2.6‰). The water-sediment ratio was estimated to be ~2. In spite of the different geological settings, the end member fuids from all vent fields are enriched in B relative to seawater (0.41 mM, 39.6‰) and the δ11B values are inversely propotional to the boron concentrations. It suggests that boron isotopic composition of vent fluid predominantly depends on the amount of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/895893','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/895893"><span>What Defines a Separate <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></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> <span class="hlt">systems</span> 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> <span class="hlt">system</span> 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> <span class="hlt">systems</span> can be hydrologically interconnected at shallower levels''.</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>Dynamics of the Yellowstone <span class="hlt">hydrothermal</span> <span class="hlt">system</span></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> <span class="hlt">system</span> 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> <span class="hlt">system</span> 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> <span class="hlt">system</span>. Specific advances include more refined geophysical images of the magmatic <span class="hlt">system</span>, 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://hdl.handle.net/2060/19930004270','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930004270"><span>Chemical environments of submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span>. 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> <span class="hlt">systems</span>. However, in the submarine <span class="hlt">systems</span> 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 <span class="hlt">systems</span> 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> <span class="hlt">systems</span>, assemble a description of the fundamental physical and chemical attributes of these <span class="hlt">systems</span>, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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/2004AGUFMOS51D..02L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFMOS51D..02L"><span>Volatiles in <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span>: Then and Now</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lilley, M. D.</p> <p>2004-12-01</p> <p>Jack Diamond was one of the principal investigators on the original proposal to dive on the Galapagos <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Jack participated on the cruise and, along with his graduate student (Richard Cobbler), made the first measurements of radon in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Louis I. Gordon and the author were also participants on this cruise and we made measurements of methane and hydrogen. In the ensuing 27 years much has been learned about volatiles in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. For example, we have learned that phase separation and water/rock reactions play major roles in the volatile composition of <span class="hlt">hydrothermal</span> fluids and that temporal variability is the rule rather than the exception. A summary of progress in this field will be given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMOS12A..04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMOS12A..04H"><span>Parameterization of and Brine Storage in MOR <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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> <span class="hlt">systems</span> 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 <span class="hlt">system</span>, δ. Of the more than 300 known <span class="hlt">systems</span>, 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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> at oceanic spreading centers undergo phase separation, yielding a low chlorinity vapor and a high salinity brine. Some <span class="hlt">systems</span> such as the Main <span class="hlt">Endeavour</span> Field on the Juan de Fuca Ridge and the 9°50’N sites 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> <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>Geothermal reservoirs in <span class="hlt">hydrothermal</span> convection <span class="hlt">systems</span></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 <span class="hlt">systems</span> 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 <span class="hlt">system</span> 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 <span class="hlt">system</span>. 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/abs/2012AGUFMOS51B1867F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS51B1867F"><span>Characterization of Magma-Driven <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> 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> <span class="hlt">systems</span> involves complex water-rock chemical reactions and phase separation. Numerical modeling of reactive transport in multi-component, multiphase <span class="hlt">systems</span> is required to obtain a full understanding of the characteristics and evolution of <span class="hlt">hydrothermal</span> vent <span class="hlt">systems</span>. 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 <span class="hlt">system</span>, magma replenishment rate, and residence time in the discharge zone. All of these key subsurface characteristics are known for fewer than 10 sites out of 300 known <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. The principal limitations of this approach stem from the uncertainty in heat output and vent field area. For <span class="hlt">systems</span> 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 <span class="hlt">Endeavour</span> 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('https://ntrs.nasa.gov/search.jsp?R=19950057138&hterms=synthesis+ammonia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsynthesis%2Bammonia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950057138&hterms=synthesis+ammonia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsynthesis%2Bammonia"><span>Thermodynamics of Strecker synthesis in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span> on the early Earth may have been the sites 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> <span class="hlt">systems</span> provide important clues for determining the potential of these and other <span class="hlt">systems</span> as sites for the emergence of life.</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>Peptide synthesis in early earth <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span> will enhance peptide chain elongation. It is anticipated that the abundant <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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://adsabs.harvard.edu/abs/2015AGUFMOS43A1993B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A1993B"><span>COVIS Detects Interconnections Between Atmospheric, Oceanic and Geologic <span class="hlt">systems</span> at a Deep Sea <span class="hlt">Hydrothermal</span> Vent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bemis, K. G.; Xu, G.; Lee, R.</p> <p>2015-12-01</p> <p>COVIS (Cabled Observatory Vent Imaging Sonar) is an innovative sonar <span class="hlt">system</span> designed to quantitatively monitor focused and diffuse flows from deep-sea <span class="hlt">hydrothermal</span> vent clusters. From 9/2010 to 9/2015, COVIS was connected to the NEPTUNE observatory at Grotto vent in the Main <span class="hlt">Endeavour</span> Field, JdFR. COVIS monitored plumes and diffuse discharge by transmitting high-frequency (200-400 kHz), pulsed acoustic waves and recording the backscattered signals to yield time series of plume heat and volume transports, plume bending, and diffuse flow area. Temporal variations indicate the rate of <span class="hlt">hydrothermal</span> plume mixing with the ambient seawater increases with the magnitude of ocean currents. Such current-driven entrainment links the dynamics of a deep-sea <span class="hlt">hydrothermal</span> plume with oceanic and atmospheric processes. We estimate the direction and relative amplitude of the local bottom currents from the bending angles of the plumes. A comparison with currents from an ADCP (~80 m south of Grotto) reveals significant complexity in the mean bottom flow structure within a <span class="hlt">hydrothermal</span> vent field. Diffuse flow area, temperature, and faunal densities vary periodically reflecting some combination of tidal pressure and current interactions. The heat transport time series suggests the heat source driving the plume remained relatively steady for 41 months. Local seismic data reveals that increased heat transport in 2000 followed seismic events in 1999 and 2000 and the steady heat flux from 10/2011 to 2/2015 coincided with quiescent seismicity. Such a correlation points to the close linkage of a seafloor <span class="hlt">hydrothermal</span> <span class="hlt">system</span> with geological processes. These findings demonstrate the intimate interconnections of seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> with processes spanning the Earth's interior to the sea surface. Further, they (and the time-series acquired by COVIS) testify to the effectiveness and robustness of employing an acoustic-imaging sonar for long-term monitoring of a seafloor <span class="hlt">hydrothermal</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040089658&hterms=Nucleotide+Sequence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNucleotide%2BSequence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040089658&hterms=Nucleotide+Sequence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNucleotide%2BSequence"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V14C..03T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V14C..03T"><span>Overview of Results from the <span class="hlt">Endeavour</span> Seismic Tomography Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toomey, D. R.; Hooft, E. E.; Wilcock, W. S.; Weekly, R. T.; Wells, A. E.; Soule, D. C.</p> <p>2011-12-01</p> <p>We report on our continuing analyses of a multi-scale seismic tomography experiment of the <span class="hlt">Endeavour</span> segment of the Juan de Fuca Ridge. In August 2009 we deployed 68 four-component ocean bottom seismometers (OBSs) at 64 sites throughout a 90x50 km2 area to record seismic energy from 5567 shots of the 36-element, 6600 in.3 airgun array of the R/V Marcus G. Langseth. The experimental geometry utilized 3 nested scales and was designed to image (1) crustal thickness variations within 25 km of the axial high (0 to 900 kyr); (2) the map view heterogeneity and anisotropy of the topmost mantle beneath the spreading axis; (3) the three-dimensional structure of the crustal magmatic <span class="hlt">system</span> and (4) the detailed three-dimensional, shallow crustal thermal structure beneath the <span class="hlt">Endeavour</span> vent fields. The 90-km-long <span class="hlt">Endeavour</span> segment lies between the Cobb and <span class="hlt">Endeavour</span> overlapping spreading centers (OSCs), which are converging and thus shortening the <span class="hlt">Endeavour</span> segment. Previous seismic reflection studies indicate that the central <span class="hlt">Endeavour</span> segment is on a 40-km-wide plateau of greater crustal thickness that is interpreted to have developed when the ridge overrode the mantle melt anomaly associated with the Heckle seamount chain. The central <span class="hlt">Endeavour</span> is also underlain by an axial magma chamber (AMC) reflector that is shallowest and most prominent beneath the <span class="hlt">hydrothermal</span> fields. Geophysical studies of <span class="hlt">Endeavour</span> thus permit investigation of the competing effects of tectonic, magmatic and <span class="hlt">hydrothermal</span> processes on crustal structure and architecture. Ongoing analyses include tomographic inversion of first-arriving P waves that sample the upper- and mid-crustal regions, characterization of off-axis magma bodies via travel time and amplitude anomalies of crustal phases, estimation of regional-scale crustal thickness variations from analysis of PmP arrivals and imaging of mantle structure using Pn to constrain mantle flow and melt distribution [Weekly et al.; Wells et al.; Soule et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://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="https://ntrs.nasa.gov/search.jsp?R=20010091026&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DSulfur"><span>The Biogeochemistry of Sulfur in <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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> <span class="hlt">systems</span>. 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> <span class="hlt">systems</span>. 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 <span class="hlt">systems</span> at 100 C. Alanine formation from propanethiol is also a favorable reaction. On the other hand, the calculated equilibrium log activities of cysteine and serine from propanethiol are -21 and -19, respectively, at 100 C. These results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18163874','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18163874"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> in small ocean planets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael</p> <p>2007-12-01</p> <p>We examine means for driving <span class="hlt">hydrothermal</span> activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of <span class="hlt">hydrothermal</span> <span class="hlt">system</span>-for example, high or low temperature <span class="hlt">system</span> or chemically driven <span class="hlt">system</span>. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of <span class="hlt">hydrothermal</span> activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive <span class="hlt">hydrothermal</span> fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive <span class="hlt">hydrothermal</span> circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T31A0483G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T31A0483G"><span><span class="hlt">Endeavour</span> basalt geology and petrology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gill, J. B.; Stakes, J.; Ramos, F.; Michael, P.; Stakes, D.</p> <p>2005-12-01</p> <p>We report major and trace element and isotope data from 250 basalt samples recently collected by submersible from the axial valley and flanks of the <span class="hlt">Endeavour</span> segment of the Juan de Fuca Ridge. Off-axis volcanism is abundant on both flanks which are mirror images of one another geologically. Axial valley walls up to 1 km off axis appear to be steps of in tact but variably fractured sheet, lobate, and hackly lava flows similar to the youngest lavas seen in collapse features in the axis. Coverage by pillow terrane increases with distance off axis and coverage becomes complete after 1 km. The similarity of the two flanks suggests that the currently asymmetric axial magma chamber (van Ark et al., 2004) may be shorter-lived than the off-axis volcanism. MgO contents range from 6.0-8.5% and generally are lower on the flanks consistent with consistently cooler chamber edges there. La/Yb ratios vary 3-fold within 100 m in the axial valley, with normalized La/Sm = 0.8-2.5 in contrast to constant Sr and Nd isotopes. However, Th/U and 230Th/232Th ratios vary only slightly in the axial valley, which may enable dating of off-axis samples. H2O/Ce is less than 170, typical of values throughout much of the Pacific. Variations in depth and degree of melting, and in source composition, are implied. At times, these heterogeneities escaped homogenization in axial magma chambers. Cl concentrations and Cl/K ratios are surprisingly low considering the active <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in close proximity and the potential for brine incorporation into the magma chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812226T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812226T"><span>Anhydrite precipitation in seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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.</p> <p>2016-04-01</p> <p>The composition and metal concentration of <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of <span class="hlt">hydrothermal</span> circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864048','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864048"><span>Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> <span class="hlt">system</span></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 <span class="hlt">system</span>, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">system</span>. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with impact structures can support colonization by microbial life. PMID:24336641</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24336641','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24336641"><span>Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan</p> <p>2013-12-16</p> <p>Impacts are common geologic features on the terrestrial planets throughout the solar <span class="hlt">system</span>, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">system</span>. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with impact structures can support colonization by microbial life.</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_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" 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_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</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="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatSR...3E3487I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatSR...3E3487I"><span>Fungal colonization of an Ordovician impact-induced <span class="hlt">hydrothermal</span> <span class="hlt">system</span></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 <span class="hlt">system</span>, and on at least Earth and Mars impacts have induced <span class="hlt">hydrothermal</span> convection. Impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> have been suggested to possess the same life supporting capability as <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">system</span>. Our results from the Lockne impact structure show that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with impact structures can support colonization by microbial life.</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>Numerical simulation of magmatic <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span> entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these <span class="hlt">systems</span> 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 <span class="hlt">system</span>, more realistic treatment of material heterogeneity in space and time, realistic description of large-scale relative permeability behavior, and intercode benchmarking comparisons. Copyright 2010 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9243011','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9243011"><span>Stable light isotope biogeochemistry of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://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> <span class="hlt">systems</span>. <span class="hlt">Hydrothermal</span> alteration of the 18O/16O and D/H values of minerals can be used to detect fossil <span class="hlt">systems</span> 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://adsabs.harvard.edu/abs/2015EGUGA..17.6314D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6314D"><span>Modelling magmatic gas scrubbing in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span>, 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 <span class="hlt">system</span> (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> <span class="hlt">systems</span></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>Porosity evolution in Icelandic <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span>, 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 <span class="hlt">systems</span>, 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 <span class="hlt">systems</span>. These are typically high enthalphy <span class="hlt">systems</span> 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> <span class="hlt">systems</span> 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://pubs.er.usgs.gov/publication/70014633','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014633"><span>CONCEPTUAL MODELS FOR THE LASSEN <span class="hlt">HYDROTHERMAL</span> <span class="hlt">SYSTEM</span>.</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> <span class="hlt">system</span>, like a number of other <span class="hlt">systems</span> 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 <span class="hlt">system</span> at depth. Two conceptual models for such <span class="hlt">systems</span> 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 <span class="hlt">systems</span>, these differences could have environmental and economic implications. Available data do not make it possible to establish a single preferred model for the Lassen <span class="hlt">system</span>, and the actual <span class="hlt">system</span> is complex enough that both models may apply to different parts of the <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=FyPMLAK-MdQ','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=FyPMLAK-MdQ"><span><span class="hlt">Endeavour</span>'s Final Voyage</span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>After nearly two decades of achievements in space, <span class="hlt">Endeavour</span> makes one last reach for the stars on its 25th and final mission, STS-134. This webcast examines the mission to come and explores the st...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=MSFC-9262853&hterms=japanese+women&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Djapanese%2Bwomen','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-9262853&hterms=japanese+women&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Djapanese%2Bwomen"><span>Space Shuttle <span class="hlt">Endeavour</span> launch</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>A smooth countdown culminated in a picture-perfect launch as the Space Shuttle <span class="hlt">Endeavour</span> (STS-47) climbed skyward atop a ladder of billowing smoke. Primary payload for the plarned seven-day flight was Spacelab-J science laboratory. The second flight of <span class="hlt">Endeavour</span> marks a number of historic firsts: the first space flight of an African-American woman, the first Japanese citizen to fly on a Space Shuttle, and the first married couple to fly in space.</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>Abiotic Organic Chemistry in <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span>.</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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span>. 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://adsabs.harvard.edu/abs/2016GeoRL..4312027P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..4312027P"><span>Geophysical imaging of shallow degassing in a Yellowstone <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pasquet, S.; Holbrook, W. S.; Carr, B. J.; Sims, K. W. W.</p> <p>2016-12-01</p> <p>The Yellowstone Plateau Volcanic Field, which hosts over 10,000 thermal features, is the world's largest active continental <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, yet very little is known about the shallow "plumbing" <span class="hlt">system</span> connecting <span class="hlt">hydrothermal</span> reservoirs to surface features. Here we present the results of geophysical investigations of shallow <span class="hlt">hydrothermal</span> degassing in Yellowstone. We measured electrical resistivity, compressional-wave velocity from refraction data, and shear wave velocity from surface-wave analysis to image shallow <span class="hlt">hydrothermal</span> degassing to depths of 15-30 m. We find that resistivity helps identify fluid pathways and that Poisson's ratio shows good sensitivity to saturation variations, highlighting gas-saturated areas and the local water table. Porosity and saturation predicted from rock physics modeling provide critical insight to estimate the fluid phase separation depth and understand the structure of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Finally, our results show that Poisson's ratio can effectively discriminate gas- from water-saturated zones in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</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>Entropy Production in Convective <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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 <span class="hlt">system</span> 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 <span class="hlt">system</span> since it accounts for dissipative heat processes and gives insight into the <span class="hlt">system</span>'s average behavior in a statistical sense. Solving the underlying conservation principles of a convective <span class="hlt">hydrothermal</span> <span class="hlt">system</span> 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 <span class="hlt">system</span> 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 <span class="hlt">systems</span>. 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://pubs.er.usgs.gov/publication/70023395','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023395"><span>Stable isotopes in seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: Vent fluids, <span class="hlt">hydrothermal</span> deposits, <span class="hlt">hydrothermal</span> alteration, and microbial processes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Shanks, Wayne C.</p> <p>2001-01-01</p> <p>The recognition of abundant and widespread <span class="hlt">hydrothermal</span> activity and associated unique life-forms on the ocean floor is one of the great scientific discoveries of the latter half of the twentieth century. Studies of seafloor <span class="hlt">hydrothermal</span> processes have led to revolutions in understanding fluid convection and the cooling of the ocean crust, the chemical and isotopic mass balance of the oceans, the origin of stratiform and statabound massive-sulfide ore-deposits, the origin of greenstones and serpentinites, and the potential importance of the subseafloor biosphere. Stable isotope geochemistry has been a critical and definitive tool from the very beginning of the modern era of seafloor exploration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9243009','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9243009"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> as environments for the emergence of life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shock, E L</p> <p>1996-01-01</p> <p>Analysis of the chemical disequilibrium provided by the mixing of <span class="hlt">hydrothermal</span> fluids and seawater in present-day <span class="hlt">systems</span> 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> <span class="hlt">systems</span> because it depends only on catalysis of thermodynamically favourable, exergonic reactions. It follows that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may be the most favourable environments for life on Earth. This fact makes <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> on the early Earth would correspond to the presence of liquid water. Evidence that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span>. 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> <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040173291&hterms=Emergence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DEmergence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040173291&hterms=Emergence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DEmergence"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">systems</span> 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> <span class="hlt">systems</span> because it depends only on catalysis of thermodynamically favourable, exergonic reactions. It follows that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may be the most favourable environments for life on Earth. This fact makes <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> on the early Earth would correspond to the presence of liquid water. Evidence that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span>. 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> <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005DSRI...52.1515O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005DSRI...52.1515O"><span>High abundances of viruses in a deep-sea <span class="hlt">hydrothermal</span> vent <span class="hlt">system</span> indicates viral mediated microbial mortality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortmann, Alice C.; Suttle, Curtis A.</p> <p>2005-08-01</p> <p>Little is known about the distribution and abundance of viruses at deep-sea <span class="hlt">hydrothermal</span> vents. Based on estimates made using epifluorescence microscopy and the dye YoPro-1, much higher viral abundances were observed at active <span class="hlt">hydrothermal</span> vents than in the surrounding deep sea. This indicates that viral production was occurring and that viruses were a source of microbial mortality. Samples collected from three actively venting sites (Clam Bed, S&M and Salut) within the <span class="hlt">Endeavour</span> Ridge <span class="hlt">system</span> off the west coast of North America had viral abundances ranging from 1.45×10 5 to 9.90×10 7 ml -1, while the abundances of prokaryotes ranged from 1.30×10 5 to 4.46×10 6 ml -1. The abundances of viruses and prokaryotes in samples collected along the neutrally buoyant plume associated with the Main <span class="hlt">Endeavour</span> Field were lower than at actively venting sites, with a mean of 5.3×10 5 prokaryotes ml -1 (s.d. 2.9×10 5, n=64) and 3.50×10 6 viruses ml -1 (s.d. 1.89×10 6, n=64), but were higher than non-plume samples (2.7×10 5 prokaryotes ml -1, s.d. 5.0×10 4, n=15 and 2.94×10 6 viruses ml -1, s.d. 1.08×10 6, n=15). Prokaryotic and viral abundances in non-<span class="hlt">hydrothermal</span> regions were as much as 10-fold higher than found in previous studies, in which sample fixation likely resulted in underestimates. This suggests that viral infection may be a greater source of prokaryotic mortality throughout the deep sea than previously recognized. Overall, our results indicate that virus-mediated mortality of prokaryotes at these <span class="hlt">hydrothermal</span>-vent environments is significant and may reduce energy flow to higher trophic levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5752591','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5752591"><span>Methane and radioactive isotopes in submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span>. 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> <span class="hlt">systems</span> along spreading axes, discovering new <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span>, 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> <span class="hlt">systems</span>. Radioisotopes in the vent waters of 21/sup 0/N high-temperature <span class="hlt">hydrothermal</span> <span class="hlt">system</span> 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 <span class="hlt">system</span> is one order of magnitude lower, and the Pb-210 activity is one order or magnitude higher, than those a the low temperature Galapagos <span class="hlt">system</span>. All these observations suggest that the high radon, and low Pb-210 activity observed in Galapagos <span class="hlt">system</span> may originate from the extensive subsurface mixing and water-rock interaction in this <span class="hlt">system</span> (direct injection of radon and scavenging of Pb-210).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=3F4u5iFIISg','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=3F4u5iFIISg"><span>Space Shuttle <span class="hlt">Endeavour</span> Heads West</span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>NASA's Shuttle Carrier Aircraft, a modified 747, flew retired shuttle <span class="hlt">Endeavour</span> from Kennedy Space Center in Florida to Houston on Sept. 19, 2012, to complete the first leg of <span class="hlt">Endeavour</span>'s trip to L...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DSRII.121...41S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DSRII.121...41S"><span>Thermal response of mid-ocean ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to perturbations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, Shreya; Lowell, Robert P.</p> <p>2015-11-01</p> <p>Mid-ocean ridges are subject to episodic disturbances in the form of magmatic intrusions and earthquakes. Following these events, the temperature of associated <span class="hlt">hydrothermal</span> vent fluids is observed to increase within a few days. In this paper, we aim to understand the rapid thermal response of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to such disturbances. We construct a classic single-pass numerical model and use the examples of the 1995 and 1999 non-eruptive events at East Pacific Rise (EPR) 9°50‧N and Main <span class="hlt">Endeavour</span> Field (MEF), respectively. We model both the thermal effects of dikes and permeability changes that might be attributed to diking and/or earthquake swarms. We find that the rapid response of vent temperatures results from steep thermal gradients close to the surface. When the perturbations are accompanied by an increase in permeability, the response on the surface is further enhanced. For EPR9°50‧N, the observed ~7 °C rise can be obtained for a ~50% increase in permeability in the diking zone. The mass flow rate increases as a result of change in permeability deeper in the <span class="hlt">system</span>, and, therefore, the amount of hot fluid in the diffused flow also increases. Using a thermal energy balance, we show that the ~10 °C increase in diffuse flow temperatures recorded for MEF after the 1999 event may result from a 3-4 times increase in permeability. The rapid thermal response of the <span class="hlt">system</span> resulting from a change in permeability also occurs for cases in which there is no additional heat input, indicating that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may respond similarly to purely seismic and non-eruptive magmatic events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H33B0793S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H33B0793S"><span>The Thermal Response of Mid-Ocean Ridge <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> to Perturbations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, S.; Lowell, R. P.</p> <p>2014-12-01</p> <p>Mid-ocean ridges are subject to episodic disturbances in the form of magmatic intrusions and earthquakes. Following these events, the temperature of associated <span class="hlt">hydrothermal</span> vent fluids is observed to increase within a few days. In this paper, we aim to understand the rapid thermal response of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to such disturbances. We construct a classic single-pass numerical model and use the examples of the 1995 and 1999 non-eruptive events at East Pacific Rise 9⁰50' N and Main <span class="hlt">Endeavour</span> Field, respectively. We model both the thermal effects of dikes and permeability changes that might be attributed to diking and/or earthquake swarms. We find that the rapid response of vent temperatures results from steep thermal gradients close to the surface. When the perturbations are accompanied by an increase in permeability, the response on the surface is enhanced further. For East Pacific Rise 9⁰50' N, the observed ~7°C rise can be obtained for a ~ 50% increase in permeability in the diking zone. The mass flow rate increases as a result of change in permeability deeper in the <span class="hlt">system</span>, and, therefore, the amount of hot fluid in the diffused flow also increases. Using a thermal energy balance, we show that the ~ 10 ⁰C increase in diffuse flow temperatures recorded for MEF after the 1999 event may result from a 3-4 times increase in permeability. The rapid thermal response of the <span class="hlt">system</span> resulting from a change in permeability also occurs for cases in which there is no additional heat input, indicating that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may respond similarly to purely seismic and non-eruptive magmatic events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5111&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5111&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss"><span><span class="hlt">Endeavour</span> after RSS rollback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>After rollback of the Rotating Service Structure, Space Shuttle <span class="hlt">Endeavour</span> shines under spotlights. At the top of the external tank is the Gaseous Oxygen Vent Arm and its vent hood, known as the '''beanie cap.''' The hood is raised to clear the external tank 2.5 minutes before launch. <span class="hlt">Endeavour</span> is targeted for launch Nov. 30 at about 10:06 p.m. EST on mission STS-97. In the background, the sky prepares for dawn. The mission to the International Space Station carries the P6 Integrated Truss Segment containing solar arrays and batteries that will be temporarily installed to the Unity connecting module by the Z1 truss, recently delivered to and installed on the Station on mission STS-92. The two solar arrays are each more than 100 feet long. They will capture energy from the sun and convert it to power for the Station. Two spacewalks will be required to install the solar array connections.</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_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" 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_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> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930034008&hterms=Submarines&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSubmarines','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930034008&hterms=Submarines&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSubmarines"><span>Chemical environments of submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. [supporting abiogenetic theory</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>The paper synthesizes diverse information about the inorganic geochemistry of submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, provides a description of the fundamental physical and chemical properties of these <span class="hlt">systems</span>, and examines the implications of high-temperature, fluid-driven processes for organic synthesis. Emphasis is on a few general features, i.e., pressure, temperature, oxidation states, fluid composition, and mineral alteration, because these features will control whether organic synthesis can occur in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12891356','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12891356"><span>Constrained circulation at <span class="hlt">Endeavour</span> ridge facilitates colonization by vent larvae.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thomson, Richard E; Mihály, Steven F; Rabinovich, Alexander B; McDuff, Russell E; Veirs, Scott R; Stahr, Frederick R</p> <p>2003-07-31</p> <p>Understanding how larvae from extant <span class="hlt">hydrothermal</span> vent fields colonize neighbouring regions of the mid-ocean ridge <span class="hlt">system</span> remains a major challenge in oceanic research. Among the factors considered important in the recruitment of deep-sea larvae are metabolic lifespan, the connectivity of the seafloor topography, and the characteristics of the currents. Here we use current velocity measurements from <span class="hlt">Endeavour</span> ridge to examine the role of topographically constrained circulation on larval transport along-ridge. We show that the dominant tidal and wind-generated currents in the region are strongly attenuated within the rift valley that splits the ridge crest, and that <span class="hlt">hydrothermal</span> plumes rising from vent fields in the valley drive a steady near-bottom inflow within the valley. Extrapolation of these findings suggests that the suppression of oscillatory currents within rift valleys of mid-ocean ridges shields larvae from cross-axis dispersal into the inhospitable deep ocean. This effect, augmented by plume-driven circulation within rift valleys having active <span class="hlt">hydrothermal</span> venting, helps retain larvae near their source. Larvae are then exported preferentially down-ridge during regional flow events that intermittently over-ride the currents within the valley.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Icar..224..347O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Icar..224..347O"><span>Impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on Earth and Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Osinski, Gordon R.; Tornabene, Livio L.; Banerjee, Neil R.; Cockell, Charles S.; Flemming, Roberta; Izawa, Matthew R. M.; McCutcheon, Jenine; Parnell, John; Preston, Louisa J.; Pickersgill, Annemarie E.; Pontefract, Alexandra; Sapers, Haley M.; Southam, Gordon</p> <p>2013-06-01</p> <p>It has long been suggested that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> might have provided habitats for the origin and evolution of early life on Earth, and possibly other planets such as Mars. In this contribution we show that most impact events that result in the formation of complex impact craters (i.e., >2-4 and >5-10 km diameter on Earth and Mars, respectively) are potentially capable of generating a <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Consideration of the impact cratering record on Earth suggests that the presence of an impact crater lake is critical for determining the longevity and size of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. We show that there are six main locations within and around impact craters on Earth where impact-generated <span class="hlt">hydrothermal</span> deposits can form: (1) crater-fill impact melt rocks and melt-bearing breccias; (2) interior of central uplifts; (3) outer margin of central uplifts; (4) impact ejecta deposits; (5) crater rim region; and (6) post-impact crater lake sediments. We suggest that these six locations are applicable to Mars as well. Evidence for impact-generated <span class="hlt">hydrothermal</span> alteration ranges from discrete vugs and veins to pervasive alteration depending on the setting and nature of the <span class="hlt">system</span>. A variety of <span class="hlt">hydrothermal</span> minerals have been documented in terrestrial impact structures and these can be grouped into three broad categories: (1) <span class="hlt">hydrothermally</span>-altered target-rock assemblages; (2) primary <span class="hlt">hydrothermal</span> minerals precipitated from solutions; and (3) secondary assemblages formed by the alteration of primary <span class="hlt">hydrothermal</span> minerals. Target lithology and the origin of the <span class="hlt">hydrothermal</span> fluids strongly influences the <span class="hlt">hydrothermal</span> mineral assemblages formed in these post-impact <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. There is a growing body of evidence for impact-generated <span class="hlt">hydrothermal</span> activity on Mars; although further detailed studies using high-resolution imagery and multispectral information are required. Such studies have only been done in detail for a handful of martian craters. The best example so</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6254717','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6254717"><span>Enhanced heat transfer in partially-saturated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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 <span class="hlt">systems</span> 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/2014PEPS....1....5N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PEPS....1....5N"><span>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> <span class="hlt">systems</span></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> <span class="hlt">systems</span>. 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 sites. 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> <span class="hlt">systems</span>. Nearly all of the deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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/895920','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/895920"><span>Fractionation of Boron Isotopes in Icelandic <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Aggarwal, J.K.; Palmer, M.R.</p> <p>1995-01-01</p> <p>Boron isotope ratios have been determined in a variety of different geothermal waters from <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> across Iceland. Isotope ratios from the high temperature meteoric water recharged <span class="hlt">systems</span> reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal <span class="hlt">systems</span> exhibit more positive {delta}{sup 11}B values than the meteoric water recharged geothermal <span class="hlt">systems</span>. Water/rock ratios can be assessed from boron isotope ratios in the saline <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Low temperature <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> also exhibit more positive {delta}{sup 11}B than the high temperature <span class="hlt">systems</span>, indicating fractionation of boron due to adsorption of the lighter isotope onto secondary minerals. Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5112&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5112&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss"><span><span class="hlt">Endeavour</span> after RSS rollback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>After rollback of the Rotating Service Structure, Space Shuttle <span class="hlt">Endeavour</span> is spotlighted against the still-black sky of pre-dawn. At the top of the external tank is the Gaseous Oxygen Vent Arm and its vent hood, known as the '''beanie cap.''' The hood is raised to clear the external tank 2.5 minutes before launch. <span class="hlt">Endeavour</span> is targeted for launch Nov. 30 at about 10:06 p.m. EST on mission STS-97. In the background, the sky prepares for dawn. The mission to the International Space Station carries the P6 Integrated Truss Segment containing solar arrays and batteries that will be temporarily installed to the Unity connecting module by the Z1 truss, recently delivered to and installed on the Station on mission STS-92. The two solar arrays are each more than 100 feet long. They will capture energy from the sun and convert it to power for the Station. Two spacewalks will be required to install the solar array connections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS22A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS22A..07S"><span>Microbiological production and ecological flux of northwestern subduction <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">system</span> 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 sites in Okinawa trough, 3 sites in Ogasawara arc, and 6 sites 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 <span class="hlt">system</span> 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> <span class="hlt">systems</span> in Okinawa trough. Microbial quantitative and spatial distribution analyses of each plume site 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.youtube.com/watch?v=hWsg3FgE-Ds','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=hWsg3FgE-Ds"><span>STS-134 Tribute to <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>STS-134 Commander Mark Kelly pays tribute to space shuttle <span class="hlt">Endeavour</span> and the spacecraft's contribution to human spaceflight. Mission specialists Andrew Feustel, Mike Fincke, Roberto Vittori, Greg C...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3133S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3133S"><span>Heat and mass transfer in volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, S. W.</p> <p>2015-12-01</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> re-distribute heat and mass derived from subsurface magma bodies over large temporal and spatial scales. Numerical models of fluid flow and heat transfer provide a quantitative basis for understanding the thermo-hydrological structure and transient behavior of volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. At the brittle-ductile transition around a magma body, the rate of conductive heat transfer from the impermeable intrusion is balanced by the rate of advective heat transfer by the fluid. Using the Complex <span class="hlt">Systems</span> Modeling Platform (CSMP++) to model fluid flow up to near-magmatic conditions, we examine the effect of geologic factors such as host rock permeability, magma emplacement depth, the temperature conditions of the brittle-ductile transition, and rock/magma thermal conductivity on the rates of heat and mass transfer around magma bodies. Additionally, we investigate the role of these factors on the thermo-hydrological structure of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, including patterns of phase separation, gravity-driven phase segregation, and fluid mixing. Passive tracers are included in the fluid flow models to simulate the input of magmatic volatiles into <span class="hlt">hydrothermal</span> fluids and their fractionation between the liquid and vapor phases. Ultimately, we compare our model results against measured heat and gas fluxes from volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to help inform the interpreation of these measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5113&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5113&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss"><span><span class="hlt">Endeavour</span> after RSS rollback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>A rising sun illuminates the coastal waters beyond Space Shuttle <span class="hlt">Endeavour</span>, poised for launch on Nov. 30 at about 10:06 p.m. EST on mission STS-97. On the left, extending toward the orbiter, is the orbiter access arm. The mission to the International Space Station carries the P6 Integrated Truss Segment containing solar arrays and batteries that will be temporarily installed to the Unity connecting module by the Z1 truss, recently delivered to and installed on the Station on mission STS-92. The two solar arrays are each more than 100 feet long. They will capture energy from the sun and convert it to power for the Station. Two spacewalks will be required to install the solar array connections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950057137&hterms=Calorie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCalorie','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950057137&hterms=Calorie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCalorie"><span>Geochemical constraints on chemolithoautotrophic reactions in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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.; Mccollom, Thomas; Schulte, Mithell D.</p> <p>1995-01-01</p> <p>Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of reduced <span class="hlt">hydrothermal</span> fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O <span class="hlt">system</span> together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of <span class="hlt">hydrothermal</span> fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from <span class="hlt">hydrothermal</span> fluids represents about 200,000 calories of chemical energy for metabolic <span class="hlt">systems</span> able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of <span class="hlt">hydrothermal</span> fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995OLEB...25..141S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995OLEB...25..141S"><span>Geochemical constraints on chemolithoautotrophic reactions in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shock, Everett L.; McCollom, Thomas; Schulte, Mitchell D.</p> <p>1995-06-01</p> <p>Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of redeuced <span class="hlt">hydrothermal</span> fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O <span class="hlt">system</span> together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of <span class="hlt">hydrothermal</span> fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from <span class="hlt">hydrothermal</span> fluids represents about 200,000 calories of chemical energy for metabolic <span class="hlt">systems</span> able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of <span class="hlt">hydrothermal</span> fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.1660B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.1660B"><span>Poroelastic response of mid-ocean ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to ocean tidal loading: Implications for shallow permeability structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barreyre, Thibaut; Sohn, Robert A.</p> <p>2016-02-01</p> <p>We use the time delay between tidal loading and exit-fluid temperature response for <span class="hlt">hydrothermal</span> vents to model the poroelastic behavior and shallow upflow zone (SUZ) effective permeability structure of three mid-ocean ridge (MOR) sites with different spreading rates. <span class="hlt">Hydrothermal</span> vents at Lucky Strike field exhibit relatively small phase lags corresponding to high SUZ effective permeabilities of ≥ ~10-10 m2, with variations that we interpret as resulting from differences in the extrusive layer thickness. By contrast, vents at East Pacific Rise site exhibit relatively large phase lags corresponding to low SUZ effective permeabilities of ≤ ~10-13 m2. Vents at Main <span class="hlt">Endeavour</span> field exhibit both high and low phase lags, suggestive of a transitional behavior. Our results demonstrate that tidal forcing perturbs <span class="hlt">hydrothermal</span> flow across the global MOR <span class="hlt">system</span>, even in places where the tidal amplitude is very low, and that the flow response can be used to constrain variations in SUZ permeability structure beneath individual vent fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MarGR.tmp....1S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MarGR.tmp....1S"><span>The potential <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> unexplored in the Southwest Indian Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suo, Yanhui; Li, Sanzhong; Li, Xiyao; Zhang, Zhen; Ding, Dong</p> <p>2017-01-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents possess complex ecosystems and abundant metallic mineral deposits valuable to human being. On-axial vents along tectonic plate boundaries have achieved prominent results and obtained huge resources, while nearly 90% of the global mid-ocean ridge and the majority of the off-axial vents buried by thick oceanic sediments within plates remain as relatively undiscovered domains. Based on previous detailed investigations, <span class="hlt">hydrothermal</span> vents have been mapped along five sections along the Southwest Indian Ridge (SWIR) with different bathymetry, spreading rates, and gravity features, two at the western end (10°-16°E Section B and 16°-25°E Section C) and three at the eastern end (49°-52°E Section D, 52°-61°E Section E and 61°-70°E Section F). <span class="hlt">Hydrothermal</span> vents along the Sections B, C, E and F with thin oceanic crust are hosted by ultramafic rocks under tectonic-controlled magmatic-starved settings, and <span class="hlt">hydrothermal</span> vents along the Section D are associated with exceed magmatism. Limited coverage of investigations is provided along the 35°-47°E SWIR (between Marion and Indomed fracture zones) and a lot of research has been done around the Bouvet Island, while no <span class="hlt">hydrothermal</span> vents has been reported. Analyzing bathymetry, gravity and geochemical data, magmatism settings are favourable for the occurrence of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> along these two sections. An off-axial <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in the southern flank of the SWIR that exhibits ultra-thin oceanic crust associated with an oceanic continental transition is postulated to exist along the 100-Ma slow-spreading isochron in the Enderby Basin. A discrete, denser enriched or less depleted mantle beneath the Antarctic Plate is an alternative explanation for the large scale thin oceanic crust concentrated on the southern flank of the SWIR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9243021','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9243021"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> on Mars: an assessment of present evidence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Farmer, J D</p> <p>1996-01-01</p> <p><span class="hlt">Hydrothermal</span> processes have been suggested to explain a number of observations for Mars, including D/H ratios of water extracted from Martian meteorites, as a means for removing CO2 from the Martian atmosphere and sequestering it in the crust as carbonates, and as a possible origin for iron oxide-rich spectral units on the floors of some rifted basins (chasmata). There are numerous examples of Martian channels formed by discharges of subsurface water near potential magmatic heat sources, and <span class="hlt">hydrothermal</span> processes have also been proposed as a mechanism for aquifer recharge needed to sustain long term erosion of sapping channels. The following geological settings have been identified as targets for ancient <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on Mars: channels located along the margins of impact crater melt sheets and on the slopes of ancient volcanoes; chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice; and the floors of calderas and rifted basins (e.g. chasmata). On Earth, such geological environments are often a locus for <span class="hlt">hydrothermal</span> mineralization. But we presently lack the mineralogical information needed for a definitive evaluation of hypotheses. A preferred tool for identifying minerals by remote sensing methods on Earth is high spatial resolution, hyperspectral, near-infrared spectroscopy, a technique that has been extensively developed by mineral explorationists. Future efforts to explore Mars for ancient <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> would benefit from the application of methods developed by the mining industry to look for similar deposits on Earth. But Earth-based exploration models must be adapted to account for the large differences in the climatic and geological history of Mars. For example, it is likely that the early surface environment of Mars was cool, perhaps consistently below freezing, with the shallow portions of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> being dominated by magma-cryosphere interactions. Given the smaller</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040173286&hterms=climatic+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dclimatic%2Bfloors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040173286&hterms=climatic+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dclimatic%2Bfloors"><span><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> on Mars: an assessment of present evidence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farmer, J. D.</p> <p>1996-01-01</p> <p><span class="hlt">Hydrothermal</span> processes have been suggested to explain a number of observations for Mars, including D/H ratios of water extracted from Martian meteorites, as a means for removing CO2 from the Martian atmosphere and sequestering it in the crust as carbonates, and as a possible origin for iron oxide-rich spectral units on the floors of some rifted basins (chasmata). There are numerous examples of Martian channels formed by discharges of subsurface water near potential magmatic heat sources, and <span class="hlt">hydrothermal</span> processes have also been proposed as a mechanism for aquifer recharge needed to sustain long term erosion of sapping channels. The following geological settings have been identified as targets for ancient <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on Mars: channels located along the margins of impact crater melt sheets and on the slopes of ancient volcanoes; chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice; and the floors of calderas and rifted basins (e.g. chasmata). On Earth, such geological environments are often a locus for <span class="hlt">hydrothermal</span> mineralization. But we presently lack the mineralogical information needed for a definitive evaluation of hypotheses. A preferred tool for identifying minerals by remote sensing methods on Earth is high spatial resolution, hyperspectral, near-infrared spectroscopy, a technique that has been extensively developed by mineral explorationists. Future efforts to explore Mars for ancient <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> would benefit from the application of methods developed by the mining industry to look for similar deposits on Earth. But Earth-based exploration models must be adapted to account for the large differences in the climatic and geological history of Mars. For example, it is likely that the early surface environment of Mars was cool, perhaps consistently below freezing, with the shallow portions of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> being dominated by magma-cryosphere interactions. Given the smaller</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B13A0200P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B13A0200P"><span>The Use of Stable Hydrogen Isotopes as a Geothermometer in <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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.; Lilley, M. D.; Früh-Green, G. L.; Olson, E. J.; Kelley, D. S.</p> <p>2004-12-01</p> <p>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 <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">hydrothermal</span> vent localities including Lost City, Middle Valley, <span class="hlt">Endeavour</span>, 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 <span class="hlt">system</span> is robust in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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 <span class="hlt">system</span> methane-hydrogen-water. Geochimica et Cosmochimica Acta, 1995. 59(24): p. 5209-5217.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040065880&hterms=Starting&qs=N%3D0%26Ntk%3DTitle%26Ntx%3Dmode%2Bmatchall%26Ntt%3DStarting','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040065880&hterms=Starting&qs=N%3D0%26Ntk%3DTitle%26Ntx%3Dmode%2Bmatchall%26Ntt%3DStarting"><span>Starting Conditions for <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> 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 <span class="hlt">System</span> 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 sites. The realization that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are possible sites for the origin and early evolution of life on Earth has given rise to the hypothesis that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">system</span>, 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> <span class="hlt">system</span> 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://adsabs.harvard.edu/abs/2016DPS....4832301C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4832301C"><span>Catalytic Diversity in Alkaline <span class="hlt">Hydrothermal</span> Vent <span class="hlt">Systems</span> on Ocean Worlds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik</p> <p>2016-10-01</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> formed by serpentinization can create moderate-temperature, alkaline <span class="hlt">systems</span> and it is possible that this type of vent could exist on icy worlds such as Europa which have water-rock interfaces. It has been proposed that some prebiotic chemistry responsible for the emergence of life on Earth and possibly other wet and icy worlds could occur as a result ofredox potential and pH gradients in submarine alkaline <span class="hlt">hydrothermal</span> vents (Russell et al., 2014). <span class="hlt">Hydrothermal</span> chimneys formed in laboratory simulations of alkaline vents under early Earth conditions have precipitate membranes that contain minerals such as iron sulfides, which are hypothesized to catalyze reduction of CO2 (Yamaguchi et al. 2014, Roldan et al. 2014) leading to further organic synthesis. This CO2 reduction process may be affected by other trace components in the chimney, e.g. nickel or organic molecules. We have conducted experiments to investigate catalytic properties of iron and iron-nickel sulfides containing organic dopants in slightly acidic ocean simulants relevant to early Earth or possibly ocean worlds. We find that the electrochemical properties of the chimney as well as the morphology/chemistry of the precipitate are affected by the concentration and type of organics present. These results imply that synthesis of organics in water-rock <span class="hlt">systems</span> on ocean worlds may lead to <span class="hlt">hydrothermal</span> precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent <span class="hlt">systems</span>.Therefore, further understanding on the electroactive roles of various organic species within <span class="hlt">hydrothermal</span> chimneys will have important implications for habitability as well as prebiotic chemistry. This work is funded by NASA Astrobiology Institute JPL Icy Worlds Team and a NAI Director's Discretionary Fund award.Yamaguchi A. et al. (2014) Electrochimica Acta, 141, 311-318.Russell, M. J. et al. (2014), Astrobiology, 14, 308-43.Roldan, A. (2014) Chem. Comm. 51</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://pubs.er.usgs.gov/publication/70017870','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017870"><span>Dynamic behavior of Kilauea Volcano and its relation to <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and geothermal energy</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kauhikaua, Jim; Moore, R.B.; ,</p> <p>1993-01-01</p> <p>Exploitation of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on active basaltic volcanoes poses some unique questions about the role of volcanism and <span class="hlt">hydrothermal</span> <span class="hlt">system</span> evolution. Volcanic activity creates and maintains <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> while earthquakes create permeable fractures that, at least temporarily, enhance circulation. Magma and water, possibly <span class="hlt">hydrothermal</span> water, can interact violently to produce explosive eruptions. Finally, we speculate on whether volcanic behavior can be affected by high rates of heat extraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21C1517M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21C1517M"><span>Monitoring <span class="hlt">Endeavour</span> vent field deep-sea ecosystem dynamics through NEPTUNE Canada seafloor observatory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matabos, M.; NC Endeavour Science Team</p> <p>2010-12-01</p> <p>Mid-ocean ridges are dynamic <span class="hlt">systems</span> where the complex linkages between geological, biological, chemical, and physical processes are not yet well understood. Indeed, the poor accessibility to the marine environment has greatly limited our understanding of deep-sea ecosystems. Undersea cabled observatories offer the power and bandwidth required to conduct long-term and high-resolution time-series observations of the seafloor. Investigations of mid-ocean ridge <span class="hlt">hydrothermal</span> ecosystem require interdisciplinary studies to better understand the dynamics of vent communities and the physico-chemical forces that influence them. NEPTUNE Canada (NC) regional observatory is located in the Northeast Pacific, off Vancouver Island (BC, Canada), and spans ecological environments from the beach to the abyss. In September-October 2010, NC will be instrumenting its 5th node, including deployment of a multi-disciplinary suite of instruments in two vent fields on the <span class="hlt">Endeavour</span> Segment of the Juan de Fuca Ridge. These include a digital camera, an imaging sonar for vent plumes and flow characteristics (i.e. COVIS), temperature resistivity probes, a water sampler and seismometers. In 2011, the TEMPO-mini, a new custom-designed camera and sensor package created by IFREMER for real-time monitoring of <span class="hlt">hydrothermal</span> faunal assemblages and their ecosystems (Sarrazin et al. 2007), and a microbial incubator, will added to the network in the Main <span class="hlt">Endeavour</span> and Mothra vent fields. This multidisciplinary approach will involve a scientific community from different institutions and countries. Significant experience aids in this installation. For example, video <span class="hlt">systems</span> connected to VENUS and NC have led to the development of new experimental protocols for time-series observations using seafloor cameras, including sampling design, camera calibration and image analysis methodologies (see communication by Aron et al. and Robert et al.). Similarly, autonomous deployment of many of the planned instruments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004EOSTr..85...37E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004EOSTr..85...37E"><span>Explorations of Mariana Arc Volcanoes Reveal New <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Embley, R. W.; Baker, E. T.; Chadwick, W. W., Jr.; Lupton, J. E.; Resing, J. A.; Massoth, G. J.; Nakamura, K.</p> <p>2004-01-01</p> <p>Some 20,000 km of volcanic arcs, roughly one-third the length of the global mid-ocean ridge (MOR) <span class="hlt">system</span>, rim the western Pacific Ocean. Compared to 25 years of <span class="hlt">hydrothermal</span> investigations along MORs, exploration of similar activity on the estimated ~600 submarine arc volcanoes is only beginning [Ishibashi and Urabe, 1995; De Ronde et al., 2003]. To help alleviate this under-sampling, the R/V T. G. Thompson was used in early 2003 (9 February to 5 March) to conduct the first complete survey of <span class="hlt">hydrothermal</span> activity along 1200 km of the Mariana intra-oceanic volcanic arc. This region includes both the Territory of Guam and the Commonwealth of the Northern Mariana Islands. The expedition mapped over 50 submarine volcanoes with stunning new clarity (Figures 1 and 2) and found active <span class="hlt">hydrothermal</span> discharge at 12 sites, including the southern back-arc site. This includes eight new sites along the arc (West Rota, Northwest Rota, E. Diamante, Zealandia Bank, Maug Caldera, Ahyi, Daikoku, and Northwest Eifuku) and four sites of previously known <span class="hlt">hydrothermal</span> activity (Seamount X, Esmeralda, Kasuga 2, and Nikko) (Figures 1 and 2). The mapping also fortuitously provided a ``before'' image of the submarine flanks of Anatahan Island, which had its first historical eruption on 10 May 2003 (Figures 1 and 3).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V22D..05R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V22D..05R"><span>Selenium Isotopes as Biosignatures in Seafloor <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rouxel, O.; Ludden, J.; Fouquet, Y.</p> <p>2001-12-01</p> <p>Chemically similar to sulphur, Se occurs as +6, +4, 0 and -2 valences in a variety of organic compounds and geological settings. This makes the study of Se stable isotope ratios a potential indicator of geological and biological processes. Se isotopes were first determined in the early 60's (Krouse and Thode, 1962; Rashid et al., 1978) using gas-source MS and recently by N-TIMS (Herbel et al., 2000; Johnson et al., 1999) using the double spike technique. The previous results showed that the 82Se/76Se ratio vary by as much as 15‰ and indicate that abiotic and bacterial reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Our isotopic analyses of Se were performed using a continuous flow hydride generation <span class="hlt">system</span> coupled to a Micromass MC-ICP-MS after chemical purification. The estimated external precision of the 82Se/76Se isotope ratio is 0.25‰ (2σ ) for a quantity of Se per analysis as low as 50 ng and the data are reported relative to our internal standards (MERCK elemental standard solution). In this study we have used Se isotopes in conjunction with S isotopes to provide additional constraints on the fractionation processes in seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Several fields were studied along the Mid Atlantic Ridge and include the Lucky Strike field where the setting is in a caldera <span class="hlt">system</span> with abundant low-permeability layers of cemented breccia which result in fluid cooling and mixing below the <span class="hlt">hydrothermal</span> vents. Based on vent structures, mineral abundance, and geochemistry, two types of <span class="hlt">hydrothermal</span> deposits were identified: (1) high-T vents with δ 34S between 1.5 and 4.5‰ and Se values up to 2000 ppm; (2) low-T vents where pyrite and marcasite generally have lower δ 34S values (down to -1.0‰ ) and low concentration of Se (<50ppm). Se-depletion in low temperature <span class="hlt">hydrothermal</span> deposits is interpreted as a result of subsurface precipitation of sulfides (scavenging Se from the fluid) during the conductive cooling of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5698254','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5698254"><span>The <span class="hlt">hydrothermal</span>-convection <span class="hlt">systems</span> of Kilauea: An historical perspective</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moore, R.B. . Federal Center); Kauahikaua, J.P. . Hawaiian Volcano Observatory)</p> <p>1993-08-01</p> <p>Kilauea is one of only two basaltic volcanoes in the world where geothermal power has been produced commercially. Little is known about the origin, size and longevity of its <span class="hlt">hydrothermal</span>-convection <span class="hlt">systems</span>. The authors review the history of scientific studies aimed at understanding these <span class="hlt">systems</span> and describe their commercial development. Geothermal energy is a controversial issue in Hawaii, partly because of hydrogen sulfide emissions and concerns about protection of rain forests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017437','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017437"><span>The <span class="hlt">hydrothermal</span>-convection <span class="hlt">systems</span> of kilauea: an historical perspective</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, R.B.; Kauahikaua, J.P.</p> <p>1993-01-01</p> <p>Kilauea is one of only two basaltic volcanoes in the world where geothermal power has been produced commercially. Little is known about the origin, size and longevity of its <span class="hlt">hydrothermal</span>-convection <span class="hlt">systems</span>. We review the history of scientific studies aimed at understanding these <span class="hlt">systems</span> and describe their commercial development. Geothermal energy is a controversial issue in Hawai'i, partly because of hydrogen sulfide emissions and concerns about protection of rain forests. ?? 1993.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1981/0915/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1981/0915/report.pdf"><span>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in southern Grass Valley, Pershing County, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Welch, Alan H.; Sorey, M.L.; Olmsted, F.H.</p> <p>1981-01-01</p> <p>Southern Grass Valley is typical extensional basin in the Basin and Range province. Leach Hot Springs, in the southern part of the valley, represents the discharge end of an active <span class="hlt">hydrothermal</span> flow <span class="hlt">system</span> with an estimated deep aquifer temperature of 163-173C. This report discusses results of geologic, hydrologic, geophysical and geochemical investigations used in an attempt to construct an internally consistent model of the <span class="hlt">system</span>. (USGS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5119283','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5119283"><span><span class="hlt">Hydrothermal</span> <span class="hlt">system</span> in Southern Grass Valley, Pershing County, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Welch, A.H.; Sorey, M.L.; Olmsted, F.H.</p> <p>1981-01-01</p> <p>Southern Grass Valley is a fairly typical extensional basin in the Basin and Range province. Leach Hot Springs, in the southern part of the valley, represents the discharge end of an active <span class="hlt">hydrothermal</span> flow <span class="hlt">system</span> with an estimated deep aquifer temperature of 163 to 176/sup 0/C. Results of geologic, hydrologic, geophysical and geochemical investigations are discussed in an attempt to construct an internally consistent model of the <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/889386','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/889386"><span>Instabilities during liquid migration into superheated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fitzgerald, Shaun D.; Woods, Andrew W.</p> <p>1995-01-26</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> typically consist of hot permeable rock which contains either liquid or liquid and saturated steam within the voids. These <span class="hlt">systems</span> vent fluids at the surface through hot springs, fumaroles, mud pools, steaming ground and geysers. They are simultaneously recharged as meteoric water percolates through the surrounding rock or through the active injection of water at various geothermal reservoirs. In a number of geothermal reservoirs from which significant amounts of hot fluid have been extracted and passed through turbines, superheated regions of vapor have developed. As liquid migrates through a superheated region of a <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, some of the liquid vaporizes at a migrating liquid-vapor interface. Using simple physical arguments, and analogue laboratory experiments we show that, under the influence of gravity, the liquid-vapor interface may become unstable and break up into fingers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JVGR..329...30B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JVGR..329...30B"><span>Geophysical image of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Merapi volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Byrdina, S.; Friedel, S.; Vandemeulebrouck, J.; Budi-Santoso, A.; Suhari; Suryanto, W.; Rizal, M. H.; Winata, E.; Kusdaryanto</p> <p>2017-01-01</p> <p>We present an image of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Merapi volcano based on results from electrical resistivity tomography (ERT), self-potential, and CO2 flux mappings. The ERT models identify two distinct low-resistivity bodies interpreted as two parts of a probably interconnected <span class="hlt">hydrothermal</span> <span class="hlt">system</span>: at the base of the south flank and in the summit area. In the summit area, a sharp resistivity contrast at ancient crater rim Pasar-Bubar separates a conductive <span class="hlt">hydrothermal</span> <span class="hlt">system</span> (20-50 Ω m) from the resistive andesite lava flows and pyroclastic deposits (2000-50,000 Ω m). The existence of preferential fluid circulation along this ancient crater rim is also evidenced by self-potential data. The significative diffuse CO2 degassing (with a median value of 400 g m-2 d-1) is observed in a narrow vicinity of the active crater rim and close to the ancient rim of Pasar-Bubar. The total CO2 degassing across the accessible summital area with a surface of 1.4 ṡ 105 m2 is around 20 t d-1. Before the 2010 eruption, Toutain et al. (2009) estimated a higher value of the total diffuse degassing from the summit area (about 200-230 t d-1). This drop in the diffuse degassing from the summit area can be related to the decrease in the magmatic activity, to the change of the summit morphology, to the approximations used by Toutain et al. (2009), or, more likely, to a combination of these factors. On the south flank of Merapi, the resistivity model shows spectacular stratification. While surficial recent andesite lava flows are characterized by resistivity exceeding 100,000 Ω m, resistivity as low as 10 Ω m has been encountered at a depth of 200 m at the base of the south flank and was interpreted as a presence of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. No evidence of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is found on the basis of the north flank at the same depth. This asymmetry might be caused by the asymmetry of the heat supply source of Merapi whose activity is moving south or/and to the asymmetry in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B13E..05R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B13E..05R"><span>Geochemical Constraints on Archaeal Diversity in the Vulcano <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rogers, K. L.; Amend, J. P.</p> <p>2006-12-01</p> <p>The shallow marine <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Vulcano, Italy hosts a wide diversity of cultured thermophilic Archaea, including Palaeococcus helgesonii, Archaeoglobus fulgidus, and Pyrococcus furiosus, to name a few. However, recent studies have revealed a plethora of uncultured archaeal lineages in the Vulcano <span class="hlt">system</span>. For example, a 16S rRNA gene survey of an onshore geothermal well identified a diverse archaeal community including deeply-branching uncultured Crenarchaeota, Korarchaeota, and Euryarchaeota. Additionally, culture-independent hybridization techniques suggested that Archaea account for nearly half of the microbial community in the Vulcano <span class="hlt">system</span>. Furthermore, geochemical characterization of fluids revealed numerous lithotrophic and heterotrophic exergonic reactions that could support as yet uncultured organisms. Archaeal diversity throughout the Vulcano <span class="hlt">hydrothermal</span> <span class="hlt">system</span> was investigated using 16S rRNA gene surveys at five submarine vents and an onshore sediment seep. Overall, archaeal diversity was higher (10 groups) at submarine vents with moderate temperatures (59°C) compared with higher temperature (94°C) vents (4 groups). Archaeal communities at the moderately thermal vents were dominated by Thermococcales and also contained Archaeoglobales, Thermoproteales, and uncultured archaea among the Korarchaeota, Marine Group I, and the Deep-sea <span class="hlt">Hydrothermal</span> Vent Euryarchaeota (DHVE). Fluid composition also affects the microbial community structure. At two high-temperature sites variations in archaeal diversity can be attributed to differences in iron and hydrogen concentrations, and pH. Comparing sites with similar temperature and pH conditions suggests that the presence of Desulfurococcales is limited to sites at which metabolic energy yields exceed 10 kJ per mole of electrons transferred. The Vulcano <span class="hlt">hydrothermal</span> <span class="hlt">system</span> hosts diverse archaeal communities, containing both cultured and uncultured species, whose distribution appears to be constrained by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS41C1832S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS41C1832S"><span>Modeling of Perturbations in Mid-Ocean <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, S.; Lowell, R. P.</p> <p>2013-12-01</p> <p>Mid-ocean ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are complex fluid circulation <span class="hlt">systems</span> straddling the locations of formation of oceanic crust. Due to the dynamic nature of the crust building process, these <span class="hlt">systems</span> are episodically subject to magmatic and seismic perturbations. Magma may be emplaced deep or shallow in the oceanic crust thereby changing the thermal structure and permeability of the <span class="hlt">system</span>. Such events would enhance <span class="hlt">hydrothermal</span> venting resulting in an increase in vent temperature and heat output along with a decrease in vent salinity in a phase separating <span class="hlt">system</span>. Event plumes, which may be associated with dike intrusions into the shallow crust, are an important class of such perturbations. In this case, the formation of low salinity vapor may add to the thermal buoyancy flux and allow the plume to rise rapidly to a considerable height above the seafloor. Additionally, seismic or tectonic disturbances may occur both deep and shallow in the crust, changing the fluid-flow structure in the <span class="hlt">system</span>. Upon knowledge of a major magmatic or seismotectonic event, temporary surveillance at the respective mid ocean ridge site is often increased as a result of rapid response cruises. One of the most common observations made after such events is the temperature of vent fluids, which is then correlated to time of observed activity and used to estimate the residence time of fluids in the <span class="hlt">system</span>. However, our numerical results indicate that for deep-seated perturbations, surface salinity may show quicker response than temperature. This result serves as our motivation to seek better understanding of propagation mechanism of perturbations through <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. We construct analytical models for fluid flow, heat and salt transfer in both single cracks and through porous media to investigate how perturbations affect both heat and salt transfer to the surface. Our preliminary results for simplified fluid circulation <span class="hlt">systems</span> tend to support the results from numerical modeling</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012947','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012947"><span>YELLOWSTONE MAGMATIC-<span class="hlt">HYDROTHERMAL</span> <span class="hlt">SYSTEM</span>, 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>Fournier, R.O.; Pitt, A.M.; ,</p> <p>1985-01-01</p> <p>At Yellowstone National Park, the deep permeability and fluid circulation are probably controlled and maintained by repeated brittle fracture of rocks in response to local and regional stress. Focal depths of earthquakes beneath the Yellowstone caldera suggest that the transition from brittle fracture to quasi-plastic flow takes place at about 3 to 4 km. The maximum temperature likely to be attained by the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is 350 to 450 degree C, the convective thermal output is about 5. 5 multiplied by 10**9 watts, and the minimum average thermal flux is about 1800 mW/m**2 throughout 2,500 km**2. The average thermal gradient between the heat source and the convecting <span class="hlt">hydrothermal</span> <span class="hlt">system</span> must be at least 700 to 1000 degree C/km. Crystallization and partial cooling of about 0. 082 km**3 of basalt or 0. 10 km**3 of rhyolite annually could furnish the heat discharged in the hot-spring <span class="hlt">system</span>. The Yellowstone magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> as a whole appears to be cooling down, in spite of a relatively large rate of inflation of the Yellowstone caldera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987JVGR...32..287G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JVGR...32..287G"><span>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of the Calabozos caldera, central Chilean Andes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grunder, Anita L.; Thompson, J. Michael; Hildreth, W.</p> <p>1987-07-01</p> <p>Active thermal springs associated with the late Pleistocene Calabozos caldera complex occur in two groups: the Colorado group which issues along structures related to caldera collapse and resurgence, and the Puesto Calabozos group, a nearby cluster that is chemically distinct and probably unrelated to the Colorado springs. Most of the Colorado group can be related to a hypothetical parent water containing ˜400 ppm Cl at ˜250°C by dilution with ≥50% of cold meteoric water. The thermal springs in the most deeply eroded part of the caldera were derived from the same parent water by boiling. The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> has probably been active for at least as long as 300,000 years, based on geologic evidence and calculations of paleo-heat flow. There is no evidence for economic mineralization at shallow depth. The Calabozos <span class="hlt">hydrothermal</span> <span class="hlt">system</span> would be an attractive geothermal prospect were its location not so remote.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015215','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015215"><span>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of the Calabozos caldera, central Chilean Andes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grunder, A.L.; Thompson, J.M.; Hildreth, W.</p> <p>1987-01-01</p> <p>Active thermal springs associated with the late Pleistocene Calabozos caldera complex occur in two groups: the Colorado group which issues along structures related to caldera collapse and resurgence, and the Puesto Calabozos group, a nearby cluster that is chemically distinct and probably unrelated to the Colorado springs. Most of the Colorado group can be related to a hypothetical parent water containing ???400 ppm Cl at ???250??C by dilution with ???50% of cold meteoric water. The thermal springs in the most deeply eroded part of the caldera were derived from the same parent water by boiling. The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> has probably been active for at least as long as 300,000 years, based on geologic evidence and calculations of paleo-heat flow. There is no evidence for economic mineralization at shallow depth. The Calabozos <span class="hlt">hydrothermal</span> <span class="hlt">system</span> would be an attractive geothermal prospect were its location not so remote. ?? 1987.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/495688','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/495688"><span>Flow and permeability structure of the Beowawe, Nevada <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Faulder, D.D.; Johnson, S.D.; Benoit, W.R.</p> <p>1997-05-01</p> <p>A review of past geologic, geochemical, hydrological, pressure transient, and reservoir engineering studies of Beowawe suggests a different picture of the reservoir than previously presented. The Beowawe <span class="hlt">hydrothermal</span> contains buoyant thermal fluid dynamically balanced with overlying cold water, as shown by repeated temperature surveys and well test results. Thermal fluid upwells from the west of the currently developed reservoir at the intersection of the Malpais Fault and an older structural feature associated with mid-Miocene rifting. A tongue of thermal fluid rises to the east up the high permeability Malpais Fault, discharges at the Geysers area, and is in intimate contact with overlying cooler water. The permeability structure is closely related to the structural setting, with the permeability of the shallow <span class="hlt">hydrothermal</span> <span class="hlt">system</span> ranging from 500 to 1,000 D-ft, while the deeper <span class="hlt">system</span> ranges from 200 to 400 D-ft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/543373','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/543373"><span><span class="hlt">Hydrothermal</span> vents is Lake Tanganyika, East African Rift <span class="hlt">system</span></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 <span class="hlt">system</span>. 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 site. 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 sites. 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 <span class="hlt">systems</span>, 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> <span class="hlt">systems</span> 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('https://www.ncbi.nlm.nih.gov/pubmed/27131783','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27131783"><span>Candidate gene prioritization with <span class="hlt">Endeavour</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tranchevent, Léon-Charles; Ardeshirdavani, Amin; ElShal, Sarah; Alcaide, Daniel; Aerts, Jan; Auboeuf, Didier; Moreau, Yves</p> <p>2016-07-08</p> <p>Genomic studies and high-throughput experiments often produce large lists of candidate genes among which only a small fraction are truly relevant to the disease, phenotype or biological process of interest. Gene prioritization tackles this problem by ranking candidate genes by profiling candidates across multiple genomic data sources and integrating this heterogeneous information into a global ranking. We describe an extended version of our gene prioritization method, <span class="hlt">Endeavour</span>, now available for six species and integrating 75 data sources. The performance (Area Under the Curve) of <span class="hlt">Endeavour</span> on cross-validation benchmarks using 'gold standard' gene sets varies from 88% (for human phenotypes) to 95% (for worm gene function). In addition, we have also validated our approach using a time-stamped benchmark derived from the Human Phenotype Ontology, which provides a setting close to prospective validation. With this benchmark, using 3854 novel gene-phenotype associations, we observe a performance of 82%. Altogether, our results indicate that this extended version of <span class="hlt">Endeavour</span> efficiently prioritizes candidate genes. The <span class="hlt">Endeavour</span> web server is freely available at https://<span class="hlt">endeavour</span>.esat.kuleuven.be/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1129&hterms=Progress+Optics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DProgress%2BOptics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1129&hterms=Progress+Optics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DProgress%2BOptics"><span>STS-113 <span class="hlt">Endeavour</span> processing with fiber-optic camera</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- With the engines removed from <span class="hlt">Endeavour</span>, the inside of <span class="hlt">Endeavour</span> is exposed. At left center, Scott Minnick, with United Space Alliance, operates a fiber-optic camera inside the flow line. Other USA team members, right, watching the progress on a screen in front, are Gerry Kathka (with controls), Mike Fore and Peggy Ritchie. The inspection is the result of small cracks being discovered on the LH2 Main Propulsion <span class="hlt">System</span> (MPS) flow liners in other orbiters. <span class="hlt">Endeavour</span> is next scheduled to fly on mission STS-113.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002910','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002910"><span>Degradation of <span class="hlt">Endeavour</span> Crater, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, J. A.; Crumpler, L. S.; Parker, T. J.; Golombek, M. P.; Wilson, S. A.; Mittlefehldt, D. W.</p> <p>2015-01-01</p> <p>The Opportunity rover has traversed portions of two western rim segments of <span class="hlt">Endeavour</span>, a 22 km-diameter crater in Meridiani Planum, for the past three years. The resultant data enables the evaluation of the geologic expression and degradation state of the crater. <span class="hlt">Endeavour</span> is Noa-chian-aged, complex in morphology, and originally may have appeared broadly similar to the more pristine 20.5 km-diameter Santa Fe complex crater in Lunae Palus (19.5degN, 312.0degE). By contrast, <span class="hlt">Endeavour</span> is considerably subdued and largely buried by younger sulfate-rich plains. Exposed rim segments dubbed Cape York (CY) and Solander Point/Murray Ridge/Pillinger Point (MR) located approximately1500 m to the south reveal breccias interpreted as remnants of the ejecta deposit, dubbed the Shoemaker Formation. At CY, the Shoemaker Formation overlies the pre-impact rocks, dubbed the Matijevic Formation.</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/2005AGUFM.V21B0601J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.V21B0601J"><span>Reconstruction of Ancestral <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> on Mount Rainier Using <span class="hlt">Hydrothermally</span> Altered Rocks in Holocene Debris Flows and Tephras</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>John, D. A.; Breit, G. N.; Sisson, T. W.; Vallance, J. W.; Rye, R. O.</p> <p>2005-12-01</p> <p> geophysical data, as well as analog fossil <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in volcanoes elsewhere, constrain <span class="hlt">hydrothermal</span> alteration geometry on the pre-Osceola-collapse edifice of Mount Rainier. Relatively narrow zones of acid magmatic-<span class="hlt">hydrothermal</span> alteration in the central core of the volcano grade to more widely distributed smectite-pyrite alteration farther out on the upper flanks, capped by steam-heated alteration with a large component of alteration resulting from condensation of fumarolic vapor above the water table. Alteration was polygenetic in zones formed episodically, and was strongly controlled by fluxes of heat and magmatic fluid and by local permeability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1171957-aqueous-geochemistry-thermopolis-hydrothermal-system-southern-bighorn-basin-wyoming','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1171957-aqueous-geochemistry-thermopolis-hydrothermal-system-southern-bighorn-basin-wyoming"><span>Aqueous geochemistry of the Thermopolis <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, southern Bighorn Basin, Wyoming, U.S.A.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Kaszuba, John P.; Sims, Kenneth W.W.; Pluda, Allison R.</p> <p>2014-06-01</p> <p>The Thermopolis <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is located in the southern portion of the Bighorn Basin, in and around the town of Thermopolis, Wyoming. It is the largest <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in Wyoming outside of Yellowstone National Park. The <span class="hlt">system</span> includes hot springs, travertine deposits, and thermal wells; published models for the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> propose the Owl Creek Mountains as the recharge zone, simple conductive heating at depth, and resurfacing of thermal waters up the Thermopolis Anticline.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561896','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561896"><span>Lithium isotope traces magmatic fluid in a seafloor <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Dan; Hou, Zengqian; Zhao, Yue; Hou, Kejun; Yang, Zhiming; Tian, Shihong; Fu, Qiang</p> <p>2015-01-01</p> <p>Lithium isotopic compositions of fluid inclusions and hosted gangue quartz from a giant volcanogenic massive sulfide deposit in China provide robust evidence for inputting of magmatic fluids into a Triassic submarine <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. The δ7Li results vary from +4.5‰ to +13.8‰ for fluid inclusions and from +6.7‰ to +21.0‰ for the hosted gangue quartz(9 gangue quartz samples containing primary fluid inclusions). These data confirm the temperature-dependent Li isotopic fractionation between <span class="hlt">hydrothermal</span> quartz and fluid (i.e., Δδ7Liquartz-fluid = –8.9382 × (1000/T) + 22.22(R2 = 0.98; 175 °C–340 °C)), which suggests that the fluid inclusions are in equilibrium with their hosted quartz, thus allowing to determine the composition of the fluids by using δ7Liquartz data. Accordingly, we estimate that the ore-forming fluids have a δ7Li range from −0.7‰ to +18.4‰ at temperatures of 175–340 °C. This δ7Li range, together with Li–O modeling , suggest that magmatic fluid played a significant role in the ore formation. This study demonstrates that Li isotope can be effectively used to trace magmatic fluids in a seafloor <span class="hlt">hydrothermal</span> <span class="hlt">system</span> and has the potential to monitor fluid mixing and ore-forming process. PMID:26347051</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>The <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> 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> <span class="hlt">system</span>. 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> <span class="hlt">system</span>. 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> <span class="hlt">system</span> for scientists and visitors. Scientists and Yellowstone Park managers carefully sited 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 site 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 site 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('https://www.osti.gov/scitech/biblio/1007864','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1007864"><span>Mechanisms of iron oxide transformation in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Otake, Tsubasa; Wesolowski, David J; Anovitz, Lawrence {Larry} M</p> <p>2010-11-01</p> <p>Coexistence of magnetite and hematite in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> has often been used to constrain the redox potential of fluids, assuming that the redox equilibrium is attained among all minerals and aqueous species. However, as temperature decreases, disequilibrium mineral assemblages may occur due to the slow kinetics of reaction involving the minerals and fluids. In this study, we conducted a series of experiments in which hematite or magnetite was reacted with an acidic solution under H{sub 2}-rich <span class="hlt">hydrothermal</span> conditions (T = 100-250 C, P{sub H{sub 2}} = 0.05-5 MPa) to investigate the kinetics of redox and non-redox transformations between hematite and magnetite, and the mechanisms of iron oxide transformation under <span class="hlt">hydrothermal</span> conditions. The formation of euhedral crystals of hematite in 150 and 200 C experiments, in which magnetite was used as the starting material, indicates that non-redox transformation of magnetite to hematite occurred within 24 h. The chemical composition of the experimental solutions was controlled by the non-redox transformation between magnetite and hematite throughout the experiments. While solution compositions were controlled by the non-redox transformation in the first 3 days in a 250 C experiment, reductive dissolution of magnetite became important after 5 days and affected the solution chemistry. At 100 C, the presence of maghemite was indicated in the first 7 days. Based on these results, equilibrium constants of non-redox transformation between magnetite and hematite and those of non-redox transformation between magnetite and maghemite were calculated. Our results suggest that the redox transformation of hematite to magnetite occurs in the following steps: (1) reductive dissolution of hematite to Fe{sub (aq)}{sup 2+} and (2) non-redox transformation of hematite and Fe{sub (aq)}{sup 2+} to magnetite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1021991','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1021991"><span>Mechanisms of iron oxide transformations in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Otake, Tsubasa; Wesolowski, David J; Anovitz, Lawrence {Larry} M; Allard Jr, Lawrence Frederick; Ohmoto, Hiroshi</p> <p>2010-01-01</p> <p>Coexistence of magnetite and hematite in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> has often been used to constrain the redox potential of fluids, assuming that the redox equilibrium is attained among all minerals and aqueous species. However, as temperature decreases, disequilibrium mineral assemblages may occur due to the slow kinetics of reaction involving the minerals and fluids. In this study, we conducted a series of experiments in which hematite or magnetite was reacted with an acidic solution under H2-rich <span class="hlt">hydrothermal</span> conditions (T = 100 250 C,) to investigate the kinetics of redox and non-redox transformations between hematite and magnetite, and the mechanisms of iron oxide transformation under <span class="hlt">hydrothermal</span> conditions. The formation of euhedral crystals of hematite in 150 and 200 C experiments, in which magnetite was used as the starting material, indicates that non-redox transformation of magnetite to hematite occurred within 24 h. The chemical composition of the experimental solutions was controlled by the non-redox transformation between magnetite and hematite throughout the experiments. While solution compositions were controlled by the non-redox transformation in the first 3 days in a 250 C experiment, reductive dissolution of magnetite became important after 5 days and affected the solution chemistry. At 100 C, the presence of maghemite was indicated in the first 7 days. Based on these results, equilibrium constants of non-redox transformation between magnetite and hematite and those of non-redox transformation between magnetite and maghemite were calculated. Our results suggest that the redox transformation of hematite to magnetite occurs in the following steps: (1) reductive dissolution of hematite to and (2) non-redox transformation of hematite and to magnetite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/840686','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/840686"><span>Products of an Artificially Induced <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> 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 Site 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> <span class="hlt">system</span> 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 site. 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://www.osti.gov/scitech/servlets/purl/6110416','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6110416"><span>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in central Twin Falls County, Idaho</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lewis, R.E.; Young, H.W.</p> <p>1989-01-01</p> <p>This report describes the results of a study to define the areal extent and thickness of the <span class="hlt">hydrothermal</span> reservoir in Twin Falls County and to propose a generalized conceptual model of the <span class="hlt">system</span>. Specific objectives of the study, done in cooperation with the Idaho Department of Water Resources, were to evaluate the existing resource as to its volume, temperature, pressure, and water chemistry, and to determine the effects of present development on the resource. The study was limited to Twin Falls County. Some geologic, geochemical, and hydrologic data for the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> were available from earlier studies. However, information about the subsurface at depths greater than 1000 feet was sparse. One well for which data were available was drilled to 2525 feet; several others were drilled to depths between 1200 and 2200 feet. Direct-current electrical resistivity soundings conducted during the summer of 1985 as part of the study provided valuable information about the subsurface at depths less than about 6000 feet. Interpretation of computer-generated subsurface profiles constructed from the soundings provided the basis for determining the thickness of the Idavada Volcanics over much of the study area. 42 refs., 9 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P33A4027G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P33A4027G"><span>Degradation of <span class="hlt">Endeavour</span> crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grant, J. A., III; Crumpler, L. S.; Parker, T. J.; Golombek, M. P.</p> <p>2014-12-01</p> <p>The Opportunity rover is traversing the western rim segments of the 22 km diameter <span class="hlt">Endeavour</span> crater in Meridiani Planum, with resultant data enabling evaluation of the craters's degradation state. The crater is Noachian in age, complex in morphology, and largely buried by younger sulfate-rich rocks. Nevertheless, exposed rim segments dubbed Cape York (CY) and Solander Point/Murray Ridge (S/M) ~1500 m to the south reveal breccias interpreted as remnants of the ejecta deposit (Shoemaker Formation or SF) that at CY overlie the pre-impact country rocks (Matijevic Formation or MF). At CY, relief is ~10 m and consists of 6-7 m of SF over at least several m of MF. By contrast, the MF/SF contact is not visible at S/M despite outcrops some 20 m below and 60 m above the elevation of the contact at CY. This implies some structural offset between the rim segments and suggests up to 70 m section is preserved at S/M. The lack of information about the orientation of the SF at S/M makes the true thickness difficult to establish, though it appears to be 10's of m more than at CY. Comparison to similar sized, fresh, complex craters on Mars and the Moon suggests there was originally 100-200 m of ejecta at <span class="hlt">Endeavour</span>'s rim. Ejecta comprise only 20-25% of the rim relief around lunar craters of similar size, thereby implying an original rim height of up to 500-1000 m at <span class="hlt">Endeavour</span>. If accurate, then ~400-800 m of the rim remains buried; the higher end of this range is close to the 800-900 m section interpreted elsewhere. If 200 m ejecta were present, then CY and S/M experienced ~190 m and over 100 m erosional lowering, respectively. If 100 m ejecta were present then rim lowering was ~90 m and 10's of m, respectively. Such differences between rim segments likely relate to changing efficiency of responsible processes and/or varying characteristics of the rocks and indicate portions of <span class="hlt">Endeavour</span> crater experienced significant degradation. A paucity of exposed debris shed from SF and MT</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15066838','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15066838"><span>Spatial distribution of marine crenarchaeota group I in the vicinity of deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takai, Ken; Oida, Hanako; Suzuki, Yohey; Hirayama, Hisako; Nakagawa, Satoshi; Nunoura, Takuro; Inagaki, Fumio; Nealson, Kenneth H; Horikoshi, Koki</p> <p>2004-04-01</p> <p>Distribution profiles of marine crenarchaeota group I in the vicinity of deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> were mapped with culture-independent molecular techniques. Planktonic samples were obtained from the waters surrounding two geographically and geologically distinct <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, and the abundance of marine crenarchaeota group I was examined by 16S ribosomal DNA clone analysis, quantitative PCR, and whole-cell fluorescence in situ hybridization. A much higher proportion of marine crenarchaeota group I within the microbial community was detected in deep-sea <span class="hlt">hydrothermal</span> environments than in normal deep and surface seawaters. The highest proportion was always obtained from the ambient seawater adjacent to <span class="hlt">hydrothermal</span> emissions and chimneys but not from the <span class="hlt">hydrothermal</span> plumes. These profiles were markedly different from the profiles of epsilon-Proteobacteria, which are abundant in the low temperatures of deep-sea <span class="hlt">hydrothermal</span> environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811039H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811039H"><span>Tracing Origin of sulfur in <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Eastern Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hsu, Hsiao-Yuan; You, Chen-Feng; Chung, Chuan-Hsiung; Aggarwal, Suresh Kumar</p> <p>2016-04-01</p> <p>Multiple sulfur isotope results and sulfate concentrations are reported for different <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in many countries. However, Taiwan is a seismically active country with plenty of hot spring resources, but only a few studies discuss about sulfur isotopes of them. No exhaustive study has been done to explain the high concentration and origin of sulfur in <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Taiwan, and chemical reaction between sulfide and sulfate. The true sulfur speciation in geothermal waters is difficult to preserve in samples for laboratory analysis. However, isotopic analysis is possible for the two species SO42- and S2O32-, together. Analysis of other species was also carried out for a possible study to understand the inter-conversion mechanism of sulfur species, and transport of other elements in aquifers, along with sulfur cycling in <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Taiwan. Fifteen samples, hot spring (5) and river water (10) were collected from East Taiwan and 5 hot spring samples were also collected from Japan for comparison. The samples were pre-concentrated and subjected to separation with anion exchange resin AGI-X8 and isotopic analysis with MC-ICPMS. The anions and cations were determined by Ion chromatography and ICP-OES, respectively. Samples from western Japan have been defined as Na-Cl type ground water and originate from 'fossil seawater' entrapped in the formations. The K/Cl and SO4/Cl ratios in hot spring water samples lie into a range between rain water and sea water. The Br/Cl ratios in hot spring water samples were close to that of sea water line, and could be distinguished from river water samples. Trace elements Li and B were high in hot spring samples from eastern Taiwan. This can be due to strong weathering in groundwater <span class="hlt">system</span>. δ34S values in most of the hot spring samples were in the range between 15.74-24.87 ‰ which is close to δ34S in seawater(+21). However, δ34S in samples from Zhiben (Taiwan) and Kurama (Japan) were -1.50‰ and -3.17 </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>Microbial Geochemistry in Shallow-Sea <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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> <span class="hlt">systems</span> are far more ubiquitous than generally recognized. Approximately 50-60 <span class="hlt">systems</span> 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 <span class="hlt">systems</span>, 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 <span class="hlt">systems</span> are often overlooked study sites. We will discuss their particular features that afford unique opportunities in microbial geochemistry. Two of the better studied examples are at Vulcano Island (Italy) and Ambitle Island (Papua New Guinea). The vents and sediment seeps at Vulcano are the "type locality" for numerous cultured hyperthermophiles, including the bacteria Aquifex and Thermotoga, the crenarchaeon Pyrodictium, and the Euryarchaeota Archaeoglobus and Pyrococcus. Isotope-labeled incubation experiments of heated sediments and an array of culturing studies have shown that simple organic compounds are predominantly fermented or anaerobically respired with sulfate. 16S rRNA gene surveys, together with fluorescent in situ hybridization studies, demonstrated the dominance of key thermophilic bacteria and archaea (e.g., Aquificales, Thermotogales, Thermococcales, Archaeoglobales) in the sediments and the presence of a broad spectrum of mostly uncultured crenarchaeota in several vent waters, sediment samples, and geothermal wells. Thermodynamic modeling quantified potential energy yields from aerobic and anaerobic respiration reactions and fermentation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70047182','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70047182"><span>Ancient impact and aqueous processes at <span class="hlt">Endeavour</span> Crater, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Squyres, S. W.; Arvidson, R. E.; Bell, J.F.; Calef, F.J.; Clark, B. C.; Cohen, B. A.; Crumpler, L.A.; de Souza, P. A.; Farrand, W. H.; Gellert, Ralf; Grant, J.; Herkenhoff, K. E.; Hurowitz, J.A.; Johnson, J. R.; Jolliff, B.L.; Knoll, A.H.; Li, R.; McLennan, S.M.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T.J.; Paulsen, G.; Rice, M.S.; Ruff, S.W.; Schröder, C.; Yen, A. S.; Zacny, K.</p> <p>2012-01-01</p> <p>The rover Opportunity has investigated the rim of <span class="hlt">Endeavour</span> Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at similar-sized craters on Earth. Highly localized zinc enrichments in some breccia materials suggest <span class="hlt">hydrothermal</span> alteration of rim deposits. Gypsum-rich veins cut sedimentary rocks adjacent to the crater rim. The gypsum was precipitated from low-temperature aqueous fluids flowing upward from the ancient materials of the rim, leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate-rich sandstones of the Meridiani region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22556248','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22556248"><span>Ancient impact and aqueous processes at <span class="hlt">Endeavour</span> Crater, Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Squyres, S W; Arvidson, R E; Bell, J F; Calef, F; Clark, B C; Cohen, B A; Crumpler, L A; de Souza, P A; Farrand, W H; Gellert, R; Grant, J; Herkenhoff, K E; Hurowitz, J A; Johnson, J R; Jolliff, B L; Knoll, A H; Li, R; McLennan, S M; Ming, D W; Mittlefehldt, D W; Parker, T J; Paulsen, G; Rice, M S; Ruff, S W; Schröder, C; Yen, A S; Zacny, K</p> <p>2012-05-04</p> <p>The rover Opportunity has investigated the rim of <span class="hlt">Endeavour</span> Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at similar-sized craters on Earth. Highly localized zinc enrichments in some breccia materials suggest <span class="hlt">hydrothermal</span> alteration of rim deposits. Gypsum-rich veins cut sedimentary rocks adjacent to the crater rim. The gypsum was precipitated from low-temperature aqueous fluids flowing upward from the ancient materials of the rim, leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate-rich sandstones of the Meridiani region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Sci...336..570S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Sci...336..570S"><span>Ancient Impact and Aqueous Processes at <span class="hlt">Endeavour</span> Crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Squyres, S. W.; Arvidson, R. E.; Bell, J. F.; Calef, F.; Clark, B. C.; Cohen, B. A.; Crumpler, L. A.; de Souza, P. A.; Farrand, W. H.; Gellert, R.; Grant, J.; Herkenhoff, K. E.; Hurowitz, J. A.; Johnson, J. R.; Jolliff, B. L.; Knoll, A. H.; Li, R.; McLennan, S. M.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T. J.; Paulsen, G.; Rice, M. S.; Ruff, S. W.; Schröder, C.; Yen, A. S.; Zacny, K.</p> <p>2012-05-01</p> <p>The rover Opportunity has investigated the rim of <span class="hlt">Endeavour</span> Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at similar-sized craters on Earth. Highly localized zinc enrichments in some breccia materials suggest <span class="hlt">hydrothermal</span> alteration of rim deposits. Gypsum-rich veins cut sedimentary rocks adjacent to the crater rim. The gypsum was precipitated from low-temperature aqueous fluids flowing upward from the ancient materials of the rim, leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate-rich sandstones of the Meridiani region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70186946','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70186946"><span>Heat flux from magmatic <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> related to availability of fluid recharge</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Harvey, M. C.; Rowland, J.V.; Chiodini, G.; Rissmann, C.F.; Bloomberg, S.; Hernandez, P.A.; Mazot, A.; Viveiros, F.; Werner, Cynthia A.</p> <p>2015-01-01</p> <p>Magmatic <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are of increasing interest as a renewable energy source. Surface heat flux indicates <span class="hlt">system</span> resource potential, and can be inferred from soil CO2 flux measurements and fumarole gas chemistry. Here we compile and reanalyze results from previous CO2 flux surveys worldwide to compare heat flux from a variety of magma-<span class="hlt">hydrothermal</span> areas. We infer that availability of water to recharge magmatic <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is correlated with heat flux. Recharge availability is in turn governed by permeability, structure, lithology, rainfall, topography, and perhaps unsurprisingly, proximity to a large supply of water such as the ocean. The relationship between recharge and heat flux interpreted by this study is consistent with recent numerical modeling that relates <span class="hlt">hydrothermal</span> <span class="hlt">system</span> heat output to rainfall catchment area. This result highlights the importance of recharge as a consideration when evaluating <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> for electricity generation, and the utility of CO2 flux as a resource evaluation tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MinDe..50..281S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MinDe..50..281S"><span>Mo isotope fractionation during <span class="hlt">hydrothermal</span> evolution of porphyry Cu <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan</p> <p>2015-03-01</p> <p>We present Mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the Kerman region, Iran. The data provide new insights into controlling processes on Mo isotope fractionation during the <span class="hlt">hydrothermal</span> evolution of porphyry <span class="hlt">systems</span>. The Mo isotope compositions of 27 molybdenite samples show wide variations in δ97Mo ranging from -0.37 to +0.92 ‰. The data reveal that molybdenites in the early and transitional stages of mineralization (preferentially 2H polytypes; δ97Mo mean = 0.35 ‰) have higher δ97Mo values than late stage (mainly 3R polytypes; δ97Mo mean = 0.02 ‰) molybdenites. This trend suggests that fractionation of Mo isotopes occurred in high-temperature stages of mineralization and that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> generally evolve towards precipitation of molybdenite with lower δ97Mo values. Taking into account the genetic models proposed for porphyry Cu deposits along with the temperature-dependent fractionation of Mo isotope ratios, it is proposed that large variations of Mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore-forming fluid phases with different density, pH, and ƒO2 properties (i.e., brine and vapor). The fractionation of Mo isotopes during fluid boiling and Rayleigh distillation processes likely dominates the Mo isotope budget of the remaining ore-forming fluids for the late stage of mineralization. The lower δ97Mo values in the late stage of mineralization can be explained by depletion of the late ore-forming <span class="hlt">hydrothermal</span> solutions in 97Mo, as these fluids have moved to considerable distance from the source. Finally, the relationship observed between MoS2 polytypes (2H and 3R) and their Mo isotopic compositions can be explained by the molecular vibration theory, in which heavier isotopes are preferentially partitioned into denser primary 2H MoS2 crystals.</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>Modeling of the fault-controlled <span class="hlt">hydrothermal</span> ore-forming <span class="hlt">systems</span></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 site 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 <span class="hlt">system</span>, confirm this concept. The influence of the fluid flow focusing on the heat and mass transfer in a single-pass advective <span class="hlt">system</span> 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 <span class="hlt">system</span> 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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> is instructive for the analysis of transport processes in man-made <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> that could develop in geologic high-level nuclear waste repositories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T31A0489T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T31A0489T"><span>Heat Flux From the <span class="hlt">Endeavour</span> Segment of the 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>Thompson, W. J.; McDuff, R. E.; Stahr, F. R.; Yoerger, D. R.; Jakuba, M.</p> <p>2005-12-01</p> <p>The very essence of a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is transfer of heat by a convecting fluid, yet the flux of heat remains a poorly known quantity. Past studies of heat flux consisted primarily of point measurements of temperature and fluid flow at individual vent sites and inventories of the neutrally buoyant plume above the field. In 2000 the Flow Mow project used the Autonomous Benthic Explorer (ABE) to determine heat flux from Main <span class="hlt">Endeavour</span> Field (MEF) on the Juan de Fuca Ridge by intersecting the stems of rising buoyant plumes. ABE carries instruments to measure conductivity, temperature and depth, and a MAVS current meter to determine the vertical velocity of the fluid, after correcting for vehicle motion. Complementary work on horizontal fluxes suggests that the vertical flux measured by ABE includes both the primary high buoyancy focused "smoker" sources and also entrained diffuse flow. In 2004, ABE was again used to determine heat flux not only from MEF, but also from the other four fields in the <span class="hlt">Endeavour</span> Segment RIDGE 2000 Integrated Study Site. In this four year interval the flux of heat from MEF has declined by approximately a factor of two. The High Rise vent field has the greatest heat flux, followed by MEF, then Mothra, Salty Dawg and Sasquatch (of order 500, 300, 100, 50 MW respectively; heat flux at Sasquatch was below detection).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H21E1176Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H21E1176Z"><span>Compartmentalized Fluid Flow In The Nevado Del Ruiz Volcano <span class="hlt">Hydrothermal</span> <span class="hlt">System(S</span>)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zuluaga, C. A.; Mejia, E.</p> <p>2011-12-01</p> <p>Combination of several extensive and compressive fault/fracture <span class="hlt">systems</span> with different lithologic units compartmentalized the <span class="hlt">hydrothermal</span> <span class="hlt">system(s</span>) in the vicinity of the Nevado del Ruiz volcano. Three main fault/fracture <span class="hlt">systems</span> are observed in the Ruiz volcano area, a N10°-20°E <span class="hlt">system</span> (San Jerónimo and Palestina faults), a N40°-60°W <span class="hlt">system</span> (Villamaría-Termales, San Ramón, Nereidas, Río Claro, San Eugenio and Campoalegrito faults), and a N60°-80°E <span class="hlt">system</span> (Santa Rosa fault). The NW trend <span class="hlt">system</span> act as the main path for fluid circulation, location of faults and fractures belonging to this <span class="hlt">system</span> and their intersections with other fault <span class="hlt">systems</span> and/or with lithologic contacts control hot springs location. The observed fault location and hot spring location pattern allow to subdivide the <span class="hlt">hydrothermal</span> <span class="hlt">system(s</span>) in at least five blocks. In the southernmost block, hot springs are mostly located in one of the four quadrants originated by fault intersections suggesting that there is a compartmentalization into higher and lower permeability quadrants. It is still unknown if all blocks belong to the same <span class="hlt">hydrothermal</span> <span class="hlt">system</span> or if there is more than one <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_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('https://pubs.usgs.gov/pp/1044a/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/1044a/report.pdf"><span>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Long Valley Caldera, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sorey, M.L.; Lewis, Robert Edward; Olmsted, F.H.</p> <p>1978-01-01</p> <p>Long Valley caldera, an elliptical depression covering 450 km 2 on the eastern front of the Sierra Nevada in east-central California, contains a hot-water convection <span class="hlt">system</span> with numerous hot springs and measured and estimated aquifer temperatures at depths of 180?C to 280?C. In this study we have synthesized the results of previous geologic, geophysical, geochemical, and hydrologic investigations of the Long Valley area to develop a generalized conceptual and mathematical model which describes the gross features of heat and fluid flow in the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Cenozoic volcanism in the Long Valley region began about 3.2 m.y. (million years) ago and has continued intermittently until the present time. The major event that resulted in the formation of the Long Valley caldera took place about 0.7 m.y. ago with the eruption of 600 km 3 or more of Bishop Tuff of Pleistocene age, a rhyolitic ash flow, and subsequent collapse of the roof of the magma chamber along one or more steeply inclined ring fractures. Subsequent intracaldera volcanism and uplift of the west-central part of the caldera floor formed a subcircular resurgent dome about 10 km in diameter surrounded by a moat containing rhyolitic, rhyodacitic, and basaltic rocks ranging in age from 0.5 to 0.05 m.y. On the basis of gravity and seismic studies, we estimate an aver- age thickness of fill of 2.4 km above the precaldera granitic and metamorphic basement rocks. A continuous layer of densely welded Bishop Tuff overlies the basement rocks, with an average thickness of 1.4 km; the fill above the welded Bishop Tuff consists of intercalated volcanic flows and tuffs and fluvial and lacustrine deposits. Assuming the average grain density of the fill is between 2.45 and 2.65 g/cm 3 , we calculate the average bulk porosity of the total fill as from 0.11 to 0.21. Comparison of published values of porosity of the welded Bishop Tuff exposed southeast of the caldera with calculated values indicates average bulk porosity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P41A3881M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P41A3881M"><span>Aqueous Alteration of <span class="hlt">Endeavour</span> Crater Rim Apron Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ming, D. W.; Mittlefehldt, D. W.; Gellert, R.; Clark, B. C.; Morris, R. V.; Yen, A. S.; Arvidson, R. E.; Crumpler, L. S.; Farrand, W. H.; Grant, J. A., III; Jolliff, B. L.; Parker, T. J.; Peretyazhko, T.</p> <p>2014-12-01</p> <p>Mars Exploration Rover Opportunity is exploring Noachian age rocks of the rim of 22 km diameter <span class="hlt">Endeavour</span> crater. Overlying the pre-impact lithologies and rim breccias is a thin apron of fine-grained sediments, the Grasberg fm, forming annuli on the lower slopes of rim segments. Hesperian Burns fm sandstones overly the Grasberg fm. Grasberg rocks have major element compositions that are distinct from Burns fm sandstones, especially when comparing interior compositions exposed by the Rock Abrasion Tool. Grasberg rocks are also different from <span class="hlt">Endeavour</span> rim breccias, but have general compositional similarities to them. Grasberg sediments are plausibly fine-grained materials derived from the impact breccias. Veins of CaSO4 transect Grasberg fm rocks demonstrating post-formation aqueous alteration. Minor/trace elements show variations consistent with mobilization by aqueous fluids. Grasberg fm rocks have low Mn and high Fe/Mn ratios compared to the other lithologies. Manganese likely was mobilized and removed from the Grasberg host rock by redox reactions. We posit that Fe2+ from acidic solutions associated with formation of the Burns sulfate-rich sandstones acted as an electron donor to reduce more oxidized Mn to Mn2+. The Fe contents of Grasberg rocks are slightly higher than in other rocks suggesting precipitation of Fe phases in Grasberg materials. Pancam spectra show that Grasberg rocks have a higher fraction of ferric oxide minerals than other <span class="hlt">Endeavour</span> rim rocks. Solutions transported Mn2+ into the <span class="hlt">Endeavour</span> rim materials and oxidized and/or precipitated it in them. Grasberg has higher contents of the mobile elements K, Zn, Cl, and Br compared to the rim materials. Similar enrichments of mobile elements were measured by the Spirit APXS on West Spur and around Home Plate in Gusev crater. Enhancements in these elements are attributed to interactions of <span class="hlt">hydrothermal</span> acidic fluids with the host rocks. Interactions of fluids with the Grasberg fm postdate the genesis</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140013102','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140013102"><span>Aqueous Alteration of <span class="hlt">Endeavour</span> Crater Rim Apron Rocks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mittlefehldt, David W.; Ming, Douglas W.; Gellert, Ralf; Clark, Benton C.; Morris, Richard V.; Yen, Albert S.; Arvidson, Raymond E.; Crumpler, Larry S.; Farrand, William H.; Grant, John A.; Jolliff, Bradley L.; Parker, Timothy J.; Peretyazhko, Tanya</p> <p>2014-01-01</p> <p>Mars Exploration Rover Opportunity is exploring Noachian age rocks of the rim of 22 km diameter <span class="hlt">Endeavour</span> crater. Overlying the pre-impact lithologies and rim breccias is a thin apron of fine-grained sediments, the Grasberg fm, forming annuli on the lower slopes of rim segments. Hesperian Burns fm sandstones overly the Grasberg fm. Grasberg rocks have major element compositions that are distinct from Burns fm sandstones, especially when comparing interior compositions exposed by the Rock Abrasion Tool. Grasberg rocks are also different from <span class="hlt">Endeavour</span> rim breccias, but have general compositional similarities to them. Grasberg sediments are plausibly fine-grained materials derived from the impact breccias. Veins of CaSO4 transect Grasberg fm rocks demonstrating post-formation aqueous alteration. Minor/trace elements show variations consistent with mobilization by aqueous fluids. Grasberg fm rocks have low Mn and high Fe/Mn ratios compared to the other lithologies. Manganese likely was mobilized and removed from the Grasberg host rock by redox reactions. We posit that Fe2+ from acidic solutions associated with formation of the Burns sulfate-rich sandstones acted as an electron donor to reduce more oxidized Mn to Mn2+. The Fe contents of Grasberg rocks are slightly higher than in other rocks suggesting precipitation of Fe phases in Grasberg materials. Pancam spectra show that Grasberg rocks have a higher fraction of ferric oxide minerals than other <span class="hlt">Endeavour</span> rim rocks. Solutions transported Mn2+ into the <span class="hlt">Endeavour</span> rim materials and oxidized and/or precipitated it in them. Grasberg has higher contents of the mobile elements K, Zn, Cl, and Br compared to the rim materials. Similar enrichments of mobile elements were measured by the Spirit APXS on West Spur and around Home Plate in Gusev crater. Enhancements in these elements are attributed to interactions of <span class="hlt">hydrothermal</span> acidic fluids with the host rocks. Interactions of fluids with the Grasberg fm postdate the genesis</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012989','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012989"><span>QUANTITATIVE ANALYSIS OF THE LASSEN <span class="hlt">HYDROTHERMAL</span> <span class="hlt">SYSTEM</span>, NORTH CENTRAL CALIFORNIA.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ingebritsen, S.E.; Sorey, M.L.</p> <p>1985-01-01</p> <p>Our conceptual model of the Lassen <span class="hlt">system</span> is termed a liquid-dominated <span class="hlt">hydrothermal</span> <span class="hlt">system</span> with a parasitic vapor-dominated zone. The essential feature of this model is that steam and steam-heated discharge at relatively high altitudes in Lassen Volcanic National Park (LVNP) and liquid discharge with high chloride concentrations at relatively low altitudes outside LVNP are both fed by an upflow of high-enthalpy two-phase fluid within the Park. Liquid flows laterally away from the upflow area toward the areas of high-chloride discharge, and steam rises through a vapor-dominated zone to feed the steam and steam-heated features. Numerical simulations show that several conditions are necessary for the development of this type of <span class="hlt">system</span>, including (1) large-scale topographic relief; (2) an initial period of convective heating within an upflow zone followed by (3) a change in hydrologic or geologic conditions that initiates drainage of liquid from portions of the upflow zone; and (4) low-permeability barriers that inhibit the movement of cold water into the vapor zone. Refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017404','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017404"><span>Geophysical characteristics of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of Kilauea volcano, Hawaii</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kauahikaua, J.</p> <p>1993-01-01</p> <p>Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data give more definition to the rift structures by allowing separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper cast rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'c fault <span class="hlt">system</span>. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). The dynamics of Kilauea eruptions are responsible for both the source of heat and the fracture permeability of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Magma supply estimates are used to calculate the rate of heat input to Kilauea's <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Heat flows of 370-820 mW/m2 are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. Heat must be dissipated by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28273951','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28273951"><span>Vein networks in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> provide constraints for the monitoring of active volcanoes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cucci, Luigi; Di Luccio, Francesca; Esposito, Alessandra; Ventura, Guido</p> <p>2017-12-01</p> <p>Vein networks affect the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of many volcanoes, and variations in their arrangement may precede <span class="hlt">hydrothermal</span> and volcanic eruptions. However, the long-term evolution of vein networks is often unknown because data are lacking. We analyze two gypsum-filled vein networks affecting the <span class="hlt">hydrothermal</span> field of the active Lipari volcanic Island (Italy) to reconstruct the dynamics of the <span class="hlt">hydrothermal</span> processes. The older network (E1) consists of sub-vertical, N-S striking veins; the younger network (E2) consists of veins without a preferred strike and dip. E2 veins have larger aperture/length, fracture density, dilatancy, and finite extension than E1. The fluid overpressure of E2 is larger than that of E1 veins, whereas the hydraulic conductance is lower. The larger number of fracture intersections in E2 slows down the fluid movement, and favors fluid interference effects and pressurization. Depths of the E1 and E2 <span class="hlt">hydrothermal</span> sources are 0.8 km and 4.6 km, respectively. The decrease in the fluid flux, depth of the <span class="hlt">hydrothermal</span> source, and the pressurization increase in E2 are likely associated to a magma reservoir. The decrease of fluid discharge in <span class="hlt">hydrothermal</span> fields may reflect pressurization at depth potentially preceding <span class="hlt">hydrothermal</span> explosions. This has significant implications for the long-term monitoring strategy of volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023045','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023045"><span>Carbon dioxide in magmas and implications for <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lowenstern, J. B.</p> <p>2001-01-01</p> <p>This review focuses on the solubility, origin, abundance, and degassing of carbon dioxide (CO2) in magma-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, with applications for those workers interested in intrusion-related deposits of gold and other metals. The solubility of CO2 increases with pressure and magma alkalinity. Its solubility is low relative to that of H2O, so that fluids exsolved deep in the crust tend to have high CO2/H2O compared with fluids evolved closer to the surface. Similarly, CO2/H2O will typically decrease during progressive decompression- or crystallization-induced degassing. The temperature dependence of solubility is a function of the speciation of CO2, which dissolves in molecular form in rhyolites (retrograde temperature solubility), but exists as dissolved carbonate groups in basalts (prograde). Magnesite and dolomite are stable under a relatively wide range of mantle conditions, but melt just above the solidus, thereby contributing CO2 to mantle magmas. Graphite, diamond, and a free CO2-bearing fluid may be the primary carbon-bearing phases in other mantle source regions. Growing evidence suggests that most CO2 is contributed to arc magmas via recycling of subducted oceanic crust and its overlying sediment blanket. Additional carbon can be added to magmas during magma-wallrock interactions in the crust. Studies of fluid and melt inclusions from intrusive and extrusive igneous rocks yield ample evidence that many magmas are vapor saturated as deep as the mid crust (10-15 km) and that CO2 is an appreciable part of the exsolved vapor. Such is the case in both basaltic and some silicic magmas. Under most conditions, the presence of a CO2-bearing vapor does not hinder, and in fact may promote, the ascent and eruption of the host magma. Carbonic fluids are poorly miscible with aqueous fluids, particularly at high temperature and low pressure, so that the presence of CO2 can induce immiscibility both within the magmatic volatile phase and in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/60580','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/60580"><span>Contact zones and <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> as analogues to repository conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wollenberg, H.A.; Flexser, S.</p> <p>1984-10-01</p> <p>Radioactive waste isolation efforts in the US are currently focused on examining basalt, tuff, salt, and crystalline rock as candidate rock types to encompass waste repositories. As analogues to near-field conditions, the distributions of radio- and trace-elements have been examined across contacts between these rocks and dikes and stocks that have intruded them. The intensive study of the Stripa quartz monzonite has also offered the opportunity to observe the distribution of uranium and its daughters in groundwater and its relationship to U associated with fracture-filling and alteration minerals. Investigations of intrusive contact zones to date have included (1) a tertiary stock into Precambrian gneiss, (2) a stock into ash flow tuff, (3) a rhyodacite dike into Columbia River basalt, and (4) a kimberlite dike into salt. With respect to temperature and pressure, these contact zones may be considered "worst-case scenario" analogues. Results indicate that there has been no appreciable migration of radioelements from the more radioactive intrusives into the less radioactive country rocks, either in response to the intrusions or in the fracture-controlled hydrological <span class="hlt">systems</span> that developed following emplacement. In many cases, the radioelements are locked up in accessory minerals, suggesting that artificial analogues to these would make ideal waste forms. Emphasis should now shift to examination of active <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, studying the distribution of key elements in water, fractures, and alteration minerals under pressure and temperature conditions most similar to those expected in the near-field environment of a repository. 14 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.V41B1394K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V41B1394K"><span>Microbial Community in the <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> 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>Kato, S.; Itahashi, S.; Kakegawa, T.; Utsumi, M.; Maruyama, A.; Ishibashi, J.; Marumo, K.; Urabe, T.; Yamagishi, A.</p> <p>2004-12-01</p> <p>There is unique ecosystem around deep-sea <span class="hlt">hydrothermal</span> area. Living organisms are supported by chemical free energy provided by the <span class="hlt">hydrothermal</span> water. The ecosystem is expected to be similar to those in early stage of life history on the earth, when photosynthetic organisms have not emerged. In this study, we have analyzed the microbial diversity in the <span class="hlt">hydrothermal</span> area at southern Mariana trough. In the "Archaean Park Project" supported by special Coordination Fund, four holes were bored and cased by titanium pipes near <span class="hlt">hydrothermal</span> vents in the southern Mariana trough in 2004. <span class="hlt">Hydrothermal</span> fluids were collected from these cased holes and natural vents in this area. Microbial cells were collected by filtering the <span class="hlt">hydrothermal</span> fluid in situ or in the mother sip. Filters were stored at -80C and used for DNA extraction. Chimneys at this area was also collected and stored at -80C. The filters and chimney samples were crushed and DNA was extracted. DNA samples were used for amplification of 16S rDNA fragments by PCR using archaea specific primers and universal primers. The PCR fragments were cloned and sequenced. These PCR clones of different samples will be compared. We will extend our knowledge about microbiological diversity at Southern Mariana trough to compare the results obtained at other area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6630994','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6630994"><span>Particulate DNA in smoker fluids: Evidence for existence of microbial populations in hot <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Straube, W.L.; Colwell, R.R. Univ. of Maryland, Baltimore ); Deming, J.W.; Baross, J.A. ); Somerville, C.C. )</p> <p>1990-05-01</p> <p>As part of an interdisciplinary study of <span class="hlt">hydrothermal</span> vents on the <span class="hlt">Endeavour</span> Segment of the Juan de Fuca Ridge, we used the submersible ALVIN to collect 57 fluid samples from 17 different hot vents (smokers and flanges) and their environs for the purpose of extracting particulate DNA. Particulate material concentrated from these samples was lysed enzymatically (enz) and by a combination of enzyme and French press treatment (fp). Concentrations of partially purified DNA recovered from these lysates were determined spectrofluorometrically. Ambient seawater surrounding the vents was found to contain low DNA concentrations, 0.18 to 0.32 ng of DNA per ml, while low-temperature vent samples yielded significantly higher concentrations of 0.37 to 2.12 ng of DNA per ml. Although DNA recovery values from superheated (210 to 345{degree}C) flange samples were not significantly different from ambient seawater values, most of the superheated (174 to 357{degree}C) smoker fluid samples contained particulate DNA in concentrations too high to be attributable to entrained seawater. Detailed sampling at one smoker site demonstrated not only the existence of significant levels of particulate DNA in the superheated smoker fluids but also the presence of an elevated microbial population in the buoyant plume 20 to 100 m above the smoker. These results underscore the heterogeneity of smoker environments within a given <span class="hlt">hydrothermal</span> vent fluid and indicate that microorganisms exist in some superheated fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010012139&hterms=Docker&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DDocker','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010012139&hterms=Docker&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DDocker"><span>STS-49 <span class="hlt">Endeavour</span>/Intelsat Briefing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>Lak Virdee of Intelsat, summarizes Intelsat's role in the STS-49 <span class="hlt">Endeavour</span> mission. He discusses the reboost hardware, giving details on the capture arm and docker adapter assembly. He describes the rendezvous between Intelsat and the <span class="hlt">Endeavour</span> Orbiter. Mr. Virdee then answers questions from the press.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS067%28S%29007&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS067%28S%29007&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ds"><span>Liftoff of STS-67 Space Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1995-01-01</p> <p>Carrying a crew of seven and a complement of astronomic experiments, the Space Shuttle <span class="hlt">Endeavour</span> embarks on NASA's longest Shuttle flight to date. <span class="hlt">Endeavour</span>'s liftoff from Launch Pad 39A occurred at 1:38:13 a.m. (EST), March 2, 1995.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS067%28S%29005&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS067%28S%29005&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ds"><span>Liftoff of STS-67 Space Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1995-01-01</p> <p>Carrying a crew of seven and a compliment of astronomic experiments, the Space Shuttle <span class="hlt">Endeavour</span> embarks on NASA's longest Shuttle flight to date. <span class="hlt">Endeavour</span>'s liftoff from Launch Pad 39A occurred at 1:38:13 a.m. (EST), March 2, 1995.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS067%28S%29003&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS067%28S%29003&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ds"><span>Launch of STS-67 Space Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1995-01-01</p> <p>Carrying a crew of seven and a complement of astronomic experiments, the Space Shuttle <span class="hlt">Endeavour</span> embarks on NASA's longest shuttle flight to date. <span class="hlt">Endeavour</span>'s liftoff from Launch Pad 39A occurred at 1:38:13 a.m. (EST), March 2, 1995. In this view the fence line near the launch pad is evident in the foreground.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29036&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29036&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds"><span>Liftoff of STS-59 Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p>The liftoff of the Space Shuttle <span class="hlt">Endeavour</span> is backdropped against a dawn sky at the Kennedy Space Center (KSC). The morning sky allows for a contrasting backdrop for the diamond shock effect of the thrust from <span class="hlt">Endeavour</span>'s main engines. Trees outline the lower portion of the view. Liftoff occurred at 7:05 a.m., April 9, 1994.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JGRB..110.2212V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JGRB..110.2212V"><span>Analogue modeling of instabilities in crater lake <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vandemeulebrouck, Jean; Stemmelen, Didier; Hurst, Tony; Grangeon, Jacques</p> <p>2005-02-01</p> <p>We carried out analogue experiments on two-phase boiling <span class="hlt">systems</span>, using a porous vertical cylinder, saturated with water. The base of the cylinder was heated, and the top was cooled, as in a natural <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Previous work had shown that once the two-phase zone reached a certain level, thermal instabilities would develop. We made measurements of the acoustic energy related to boiling, and we found that high levels of acoustic noise were associated with the part of the cycle in which there was upward water movement. We repeated our experiments with a cooling water tank at the top of the <span class="hlt">system</span>, representing a crater lake. This showed that periodic thermal instabilities still developed in this situation. We then compared our analogue measurements to two natural <span class="hlt">systems</span> known to exhibit periodic behavior. There is good agreement between the thermal and acoustic cycling seen in our model and the observations made at Inferno Crater Lake in the Waimangu Geothermal area, New Zealand, whose level cycles by nearly 10 m, with a typical period of 38 days. Particularly notable is how in both <span class="hlt">systems</span> high levels of acoustic noise are associated with rising water level. The much larger Ruapehu Crater Lake, also in New Zealand, cycled with a period of several months to a year for over a decade prior to the 1995 eruption. Strong acoustic and seismic energy usually occurred just before the lake temperature started to rise. This suggests a slightly different model, in which the increasing two-phase flow zone triggers more general convection once it reaches the base of the lake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1890497','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1890497"><span>Extreme accumulation of nucleotides in simulated <span class="hlt">hydrothermal</span> pore <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Baaske, Philipp; Weinert, Franz M.; Duhr, Stefan; Lemke, Kono H.; Russell, Michael J.; Braun, Dieter</p> <p>2007-01-01</p> <p>We simulate molecular transport in elongated <span class="hlt">hydrothermal</span> pore <span class="hlt">systems</span> influenced by a thermal gradient. We find extreme accumulation of molecules in a wide variety of plugged pores. The mechanism is able to provide highly concentrated single nucleotides, suitable for operations of an RNA world at the origin of life. It is driven solely by the thermal gradient across a pore. On the one hand, the fluid is shuttled by thermal convection along the pore, whereas on the other hand, the molecules drift across the pore, driven by thermodiffusion. As a result, millimeter-sized pores accumulate even single nucleotides more than 108-fold into micrometer-sized regions. The enhanced concentration of molecules is found in the bulk water near the closed bottom end of the pore. Because the accumulation depends exponentially on the pore length and temperature difference, it is considerably robust with respect to changes in the cleft geometry and the molecular dimensions. Whereas thin pores can concentrate only long polynucleotides, thicker pores accumulate short and long polynucleotides equally well and allow various molecular compositions. This setting also provides a temperature oscillation, shown previously to exponentially replicate DNA in the protein-assisted PCR. Our results indicate that, for life to evolve, complicated active membrane transport is not required for the initial steps. We find that interlinked mineral pores in a thermal gradient provide a compelling high-concentration starting point for the molecular evolution of life. PMID:17494767</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T51D2614Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T51D2614Y"><span>Role of tectonic and volcanic activity in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at the southern Mariana Trough: detailed bathymetric characteristics of the <span class="hlt">hydrothermal</span> sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshikawa, S.; Okino, K.; Asada, M.; Nogi, Y.; Mochizuki, N.; Nakamura, K.</p> <p>2012-12-01</p> <p>We present the detailed bathymetric characterization of field-scale geological features associated with <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the southern Mariana Trough near 12°57'N, 143°37'E, using near-bottom swath mapping data collected by the autonomous underwater vehicle (AUV) Urashima during cruise YK09-08 and dive observation data acquired by the submersible Shinkai6500 during cruise YK10-11. In the study area, two of the <span class="hlt">hydrothermal</span> sites are located on the active backarc spreading axis (the Snail and Yamanaka sites), one is located at the eastern foot of the axial high (the Archean site), and two are located on an off-axis knoll about 5 km from the spreading axis (the Pika and Urashima sites). We examined 1) the nature of' tectonic and volcanic controls on the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, and 2) the relationship between geomorphological characteristics and <span class="hlt">hydrothermal</span> activity based on the survey results (Yoshikawa et al., 2012). The two on-axis <span class="hlt">hydrothermal</span> sites are possibly locally developed on a 4th order spreading segment, in association with diking events (on the basis of comparisons with previously studied cases on the East Pacific Rise). The three off-axis sites (the Archean, Urashima, and Pika sites) appear to represent locations of sustained <span class="hlt">hydrothermal</span> activity that has created relatively large-scale <span class="hlt">hydrothermal</span> features compared with those in the on-axis area. The formation of off-axis <span class="hlt">hydrothermal</span> sites is likely to be closely related to an off-axis magma upwelling <span class="hlt">system</span>, as evidenced by the absence of fault <span class="hlt">systems</span> and the undeformed morphology of the mound and knoll. The three off-axis <span class="hlt">hydrothermal</span> sites are composed mainly of breccia assemblages that probably originated from <span class="hlt">hydrothermal</span> activity with black smoker venting. These areas are characterized by numerous ridge lines (height, mainly 1-6 m), conical mounds (height: < 100 m, diameter: < 300 m), and bumpy seabed. Most of the ridge lines have formed as a result of collapse of the seafloor. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010LPICo1538.5636P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010LPICo1538.5636P"><span>Terrestrial Iron Hot Springs as Analogs for Ancient Martian <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parenteau, M. N.; Farmer, J. D.; Jahnke, L. L.; Cady, S. L.</p> <p>2010-04-01</p> <p>We have been studying a subaerial terrestrial iron hot spring as an potential analog for <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on Mars. In this multidisciplinary study, we have characterized the aqueous geochemistry, mineralogy, and microbial biosignatures at Chocolate Pots hot springs.</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>Near-Seafloor Magnetic Exploration of Submarine <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> 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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> 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 sites as well as being a tool for the discovery of previously unknown <span class="hlt">hydrothermal</span> sites. Significant differences exist between the magnetic expressions of <span class="hlt">hydrothermal</span> sites 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 sites.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B13A0179B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B13A0179B"><span>Current Research at the <span class="hlt">Endeavour</span> Ridge 2000 Integrated Studies Site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Butterfield, D. A.; Kelley, D. S.; Ridge 2000 Community, R.</p> <p>2004-12-01</p> <p> investigations at MEF, Mothra, Sasquatch, and Middle Valley, collecting fluid, particle, and animal samples for culture and phylogenetic analysis. al Tiburon continued in late August/September with detailed petrological sampling. A Keck-sponsored al Thompson/ROPOS cruise in September continued work on chemical/physical sensor deployments and time-series chemical and microbial sampling. A graduate student workshop at Friday Harbor beginning October 2004 will analyze the first year of data from the seismic network and begin to correlate seismic activity with <span class="hlt">hydrothermal</span> activity. The <span class="hlt">Endeavour</span> ISS is still in a phase of data collection and sensor development, but moving toward data integration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/472054','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/472054"><span><span class="hlt">Hydrothermal</span> model of the Momotombo geothermal <span class="hlt">system</span>, Nicaragua</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Verma, M.P.; Martinez, E.; Sanchez, M.; Miranda, K.</p> <p>1996-12-31</p> <p>The Momotombo geothermal field is situated on the northern shore of Lake Managua at the foot of the active Momotombo volcano. The field has been producing electricity since 1983 and has an installed capacity of 70 MWe. The results of geological, geochemical and geophysical studies have been reported in various internal reports. The isotopic studies were funded by the International Atomic Energy Agency (IAEA), Vienna to develop a <span class="hlt">hydrothermal</span> model of the geothermal <span class="hlt">system</span>. The chemical and stable isotopic data ({delta}{sup 18}O and {delta}D) of the geothermal fluid suggest that the seasonal variation in the production characteristics of the wells is related to the rapid infiltration of local precipitation into the reservoir. The annual average composition of Na{sup +}, K{sup +} and Mg{sup 2+} plotted on the Na-K-Mg triangular diagram presented by Giggenbach (1988) to identify the state of rock-water interaction in geothermal reservoirs, shows that the fluids of almost every well are shifting towards chemically immature water due to reservoir exploitation. This effect is prominent in wells Mt-2, Mt-12, Mt-22 and Mt-27. The local groundwaters including surface water from Lake Managua have much lower tritium concentrations than some of the geothermal well fluids, which have about 6 T.U. The high-tritium wells are located along a fault inferred from a thermal anomaly. The tritium concentration is also higher in fluids from wells close to the lake. This could indicate that older local precipitation waters are stored in a deep layer within the lake and that they are infiltrating into the geothermal reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/889656','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/889656"><span><span class="hlt">Hydrothermal</span> model of the Momotombo geothermal <span class="hlt">system</span>, Nicaragua</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Verma, M.P.; Martinez, E.; Sanchez, M.; Miranda, K.; Gerardo, J.Y.; Araguas, L.</p> <p>1996-01-24</p> <p>The Momotombo geotherinal field is situated on the northern shore of Lake Managua at the foot of the active Momotombo volcano. The field has been producing electricity since 1983 and has an installed capacity of 70 MWe. The results of geological, geochemical and geophysical studies have been reported in various internal reports. The isotopic studies were funded by the International Atomic Energy Agency (IAEA), Vienna to develop a <span class="hlt">hydrothermal</span> model of the geothermal <span class="hlt">system</span>. The chemical and stable isotopic data (δ<sup>18</sup>O and δD) of the geothermal fluid suggest that the seasonal variation in the production characteristics of the wells is related to the rapid infiltration of local precipitation into the reservoir. The annual average composition of Na<sup>+</sup>, K<sup>+</sup> and Mg<sup>2+</sup> plotted on the Na- K-Mg triangular diagram presented by Giggenbach (1988) to identify the state of rock-water interaction in geothermal reservoirs, shows that the fluids of almost every well are shifting towards chemically immature water due to resenroir exploitation. This effect is prominent in wells Mt-2. Mt-12, Mt-22 and Mt-27. The local groundwaters including surface water from Lake Managua have much lower tritium concentrations than sonic of the geothermal well fluids, which have about 6 T.U. The high-tritium wells are located along a fault inferred froin a thermal anomaly. The tritium concentration is also higher in fluids from wells close to the lake. This could indicate that older local precipitation waters are stored in a deep layer within the lake and that they are infiltrating into the geothermal reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Geo....21..113J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Geo....21..113J"><span>Zonation patterns of skarn garnets: Records of <span class="hlt">hydrothermal</span> <span class="hlt">system</span> evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jamtveit, Bjørn; Wogelius, Roy A.; Fraser, Donald G.</p> <p>1993-02-01</p> <p>Chemically zoned skarn garnets provide a continuous record of <span class="hlt">hydrothermal</span> processes in lower Paleozoic sedimentary rocks within the contact aureole around the Drammen granite in the Oslo rift, southern Norway. Major and trace element zonation profiles, the latter obtained using a scanning high-resolution proton microprobe, reveal early infiltration-controlled growth of relatively grossular rich garnets, the major and trace elements compositions being buffered by local mineral dissolution. Subsequent rapid, epitaxial growth of andradite-rich garnet on grossular-rich cores marks the onset of vigorous and focused fluid flow along high-permeability zones. During this later stage, the <span class="hlt">hydrothermal</span> fluid composition was to a large extent externally controlled, and the andradite precipitating from these fluids was characterized by high As and W contents. The zonation patterns of the andradite-rich garnets record at least five intermittent growth periods, with rapid andradite precipitation from fluid batches with high f</em>O2, and progressively decreasing As and W contents. Thin layers, poor in Fe, As, and W, but relatively high in Al and Mn, represent periods of slow growth rates between the major pulses of <span class="hlt">hydrothermal</span> fluids. The marked rimward decrease in the As and W contents of the garnets may reflect influx of meteoric waters or exhaustion of these elements in the <span class="hlt">hydrothermal</span> fluid reservoir caused by boiling-controlled distillation processes at depth.</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>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 <span class="hlt">Endeavour</span> Segment of the Juan de Fuca Ridge, located 6 km north of the Main <span class="hlt">Endeavour</span> 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 <span class="hlt">system</span> and Imagenex scanning sonar at a resolution of 1-5 m. These data were combined with visual imagery from Alvin and ROV dives to define the eruptive, <span class="hlt">hydrothermal</span>, and tectonic characteristics of the field and distal areas. Based on multibeam sonar results, bathymetric relief of the segment near Sasquatch is subdued. The broad axial valley is split by a central high that rises 30-40 m above the surrounding seafloor. Simple pattern analysis of the valley shows two fundamentally different regions, distinguished by low and high local variance. Areas of low variance correspond to a collapse/drainback landscape characterized by ropy sheet flow, basalt pillars, and bathtub rings capped by intact and drained lobate flows. Areas of high variance generally correspond to three types of ridge structures: 1) faulted basalt ridges composed of truncated pillow basalt, rare massive flows, and widespread pillow talus; 2) constructional basalt ridges composed of intact pillow flow fronts; and 3) extinct sulfide ridges covered by varying amounts of sulfide talus and oxidized <span class="hlt">hydrothermal</span> sediment. Sasquatch is located in a depression among truncated pillow ridges, and is comprised of ~10, 1-6 m high, fragile sulfide chimneys that vent fluids up to 289°C. The active field extends only ~25 x 25 m, although a linear, N-S trending ridge of nearly continuous extinct sulfide</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22970260','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22970260"><span>Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi</p> <p>2012-01-01</p> <p>To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea <span class="hlt">hydrothermal</span> vent <span class="hlt">systems</span> off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white <span class="hlt">hydrothermal</span> vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different <span class="hlt">hydrothermal</span> plumes. The bacterial and archaeal communities from the white <span class="hlt">hydrothermal</span> plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow <span class="hlt">hydrothermal</span> plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4)) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4) was less tied to microbial processes in this shallow-sea <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. We speculated that mixing between <span class="hlt">hydrothermal</span> fluids and the sea or meteoric water leads to distinctly different CH(4) concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> off the coast of NE Taiwan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=aGeZixp264E','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=aGeZixp264E"><span><span class="hlt">Endeavour</span> Mated to SCA Time-Lapse</span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>At the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, space shuttle <span class="hlt">Endeavour</span> is mounted atop NASA's Shuttle Carrier Aircraft, or SCA, in preparation for its ferry flight to Ca...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=Vhxj4fegSA4','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=Vhxj4fegSA4"><span><span class="hlt">Endeavour</span> Begins Ferry Flight to LA</span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>Space shuttle <span class="hlt">Endeavour</span> and the Shuttle Carrier Aircraft took off Wednesday morning, Sept. 19, from NASA's Kennedy Space Center in Florida to begin the first leg of a mission to deliver the retired...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=9WlakQkH2wk','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=9WlakQkH2wk"><span>Shuttle <span class="hlt">Endeavour</span> Flyover of Los Angeles Landmarks</span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>Space shuttle <span class="hlt">Endeavour</span> atop NASA's Shuttle Carrier Aircraft flew over many Los Angeles area landmarks on its final ferry flight Sept. 21, 2012, including the Coliseum, the Hollywood Sign, Griffith...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813062W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813062W"><span>Geologic and hydrologic controls on the economic potential of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with upper crustal plutons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weis, Philipp; Driesner, Thomas; Scott, Samuel; Lecumberri-Sanchez, Pilar</p> <p>2016-04-01</p> <p>Heat and mass transport in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with upper crustal magmatic intrusions can result in resources with large economic potential (Kesler, 1994). Active <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> can form high-enthalpy geothermal reservoirs with the possibility for renewable energy production. Fossil continental or submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may have formed ore deposits at variable crustal depths, which can be mined near today's surface with an economic profit. In both cases, only the right combination of first-order geologic and hydrologic controls may lead to the formation of a significant resource. To foster exploration for these <span class="hlt">hydrothermal</span> georesources, we need to improve our understanding of subsurface fluxes of mass and energy by combining numerical process modelling, observations at both active and fossil <span class="hlt">systems</span>, as well as knowledge of fluid and rock properties and their interactions in natural <span class="hlt">systems</span>. The presentation will highlight the role of non-linear fluid properties, phase separation, salt precipitation, fluid mixing, permeability structure, hydraulic fracturing and the transition from brittle to ductile rock behavior as major geologic and hydrologic controls on the formation of high-enthalpy and supercritical geothermal resources (Scott et al., 2015), and magmatic-<span class="hlt">hydrothermal</span> mineral resources, such as porphyry copper, massive sulfide and epithermal gold deposits (Lecumberri-Sanchez et al., 2015; Weis, 2015). References: Kesler, S. E., 1994: Mineral Resources, economics and the environment, New York, McMillan, 391. Lecumberri-Sanchez, P., Steele-MacInnis, M., Weis, P., Driesner, T., Bodnar, R.J. (2015): Salt precipitation in magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> associated with upper crustal plutons. Geology, v. 43, p. 1063-1066, doi:10.1130/G37163.1 Scott, S., Driesner, T., Weis, P. (2015): Geologic controls on supercritical geothermal resources above magmatic intrusions. Nature Communications, 6:7837 doi: 10.1038/ncomms8837 Weis, P. (2015): The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52..351S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52..351S"><span>Evidence for a spatially extensive <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Ries impact structure, Germany</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sapers, H. M.; Osinski, G. R.; Flemming, R. L.; Buitenhuis, E.; Banerjee, N. R.; Tornabene, L. L.; Blain, S.; Hainge, J.</p> <p>2017-02-01</p> <p>The 15 Ma, 26 km diameter Ries impact structure in south-central Germany was one of the first terrestrial impact structures where evidence of impact-associated <span class="hlt">hydrothermal</span> alteration was recognized. Previous studies suggested that pervasive, high-temperature <span class="hlt">hydrothermal</span> activity was restricted to the area within the "inner ring" (i.e., the crater-fill impactite units). Here we present mineralogical evidence for localized <span class="hlt">hydrothermal</span> activity in the ejecta beyond the crater rim in two previously unstudied settings: a pervasively altered lens of suevite ejecta directly overlying the Bunte Breccia at the Aumühle quarry; and suevite ejecta at depth overlain by 20 m of lacustrine sediments sampled by the Wörnitzostheim 1965 drill core. A comprehensive set of X-ray diffraction analyses indicates five distinct alteration regimes (1) surficial ambient weathering characterized by smectite and a minor illitic component; (2) locally restricted <span class="hlt">hydrothermal</span> activity characterized by an illitic component and minor smectite; (3) <span class="hlt">hydrothermal</span> activity at depth characterized by smectite, a minor illitic component, and calcite; (4) <span class="hlt">hydrothermal</span> activity at depth characterized by smectite, a minor illitic component, calcite, zeolites, and clinochlore; and (5) pervasive <span class="hlt">hydrothermal</span> activity at depth characterized by smectite, a minor illitic component, and minor clinochlore. These data spatially extend the Ries postimpact <span class="hlt">hydrothermal</span> <span class="hlt">system</span> suggesting a much more extensive, complex, and dynamic <span class="hlt">system</span> than previously thought. Constraining the mineralogical alteration regimes at the Ries impact structure may also further our understanding of impact-associated phyllosilicate formation on Mars with implications for climate models and habitability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JVGR..160...23M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JVGR..160...23M"><span>Textural and mineralogical changes associated with the incipient <span class="hlt">hydrothermal</span> alteration of glassy dacite at the submarine PACMANUS <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, eastern 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>Monecke, T.; Giorgetti, G.; Scholtysek, O.; Kleeberg, R.; Götze, J.; Hannington, M. D.; Petersen, S.</p> <p>2007-02-01</p> <p>Variably altered dacite from the PACMANUS vent field in the eastern Manus back-arc basin, Papua New Guinea, was studied to determine the textural and mineralogical characteristics of <span class="hlt">hydrothermal</span> alteration taking place in the immediate subsurface of this modern seafloor <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Detailed textural investigations show that fluid flow through the glassy dacite has been strongly controlled by the primary volcanic textures. Quench fractures and networks of interconnected perlitic cracks linking vesicles provided pathways for <span class="hlt">hydrothermal</span> fluids flowing up to the seafloor. <span class="hlt">Hydrothermal</span> alteration along these pathways resulted in the formation of pseudoclastic textures. Textural evidence suggests that alteration of the glassy dacite has not been sustained. The samples have been affected by incipient <span class="hlt">hydrothermal</span> alteration that is typically not preserved in ancient volcanic-rock-hosted massive sulfide deposits. Interaction of the glassy dacite with <span class="hlt">hydrothermal</span> fluids primarily resulted in the conversion of volcanic glass to dioctahedral smectite. Only minor amounts of trioctahedral smectite were formed. Destruction of the volcanic glass and the formation of smectite caused pronounced changes in the chemistry of the dacite samples, in particular a decrease in the SiO 2 whole-rock content and the Na 2O/K 2O ratio. The two alkali elements behaved differently during <span class="hlt">hydrothermal</span> alteration due to preferential incorporation of K into the interlayer position of the newly formed dioctahedral smectite. Smectite formation occurred under rock-dominated conditions although the addition of Mg was required to form trioctahedral smectite from the silicic volcanic glass. Primary plagioclase was resistant to <span class="hlt">hydrothermal</span> alteration highlighting the fact that the destruction of volcanic glass and feldspar are not necessarily contemporaneous in massive sulfide forming <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Incipient alteration of the glassy dacite close to the seafloor occurred at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6614I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6614I"><span>Hydrogeological structure of a seafloor <span class="hlt">hydrothermal</span> <span class="hlt">system</span> related to backarc rifting in a continental margin setting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishibashi, Jun-ichiro</p> <p>2016-04-01</p> <p>Seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the Okinawa Trough backarc basin are considered as related to backarc rifting in a continental margin setting. Since the seafloor is dominantly covered with felsic volcaniclastic material and/or terrigenous sediment, <span class="hlt">hydrothermal</span> circulation is expected to be distributed within sediment layers of significantly high porosity. Deep drilling through an active <span class="hlt">hydrothermal</span> field at the Iheya North Knoll in the middle Okinawa Trough during IODP Expedition 331 provided a unique opportunity to directly access the subseafloor. While sedimentation along the slopes of the knoll was dominated by volcanic clasts of tubular pumice, intense <span class="hlt">hydrothermal</span> alteration was recognized in the vicinity of the <span class="hlt">hydrothermal</span> center even at very shallow depths. Detailed mineralogical and geochemical studies of <span class="hlt">hydrothermal</span> clay minerals in the altered sediment suggest that the prevalent alteration is attributed to laterally extensive fluid intrusion and occupation within the sediment layer. Onboard measurements of physical properties of the obtained sediment revealed drastic changes of the porosity caused by <span class="hlt">hydrothermal</span> interactions. While unaltered sediment showed porosity higher than 70%, the porosity drastically decreased in the layer of anhydrite formation. On the other hand, the porosity remained high (~50%) in the layer of only chlorite alteration. Cap rock formation caused by anhydrite precipitation would inhibit the ascent of high temperature fluids to the seafloor. Moreover, an interbedded nature of pelagic mud units and matrix-free pumice deposits may prompt formation of a tightly layered architecture of aquifers and aquicludes. This sediment architecture should be highly conducive to lateral flow pseudo-parallel to the surface topography. Occurrence of sphalerite-rich sulfides was recognized as associated with detrital and altered sediment, suggesting mineralization related to subsurface chemical processes. Moreover, the vertical profiles of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22928928','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22928928"><span>Microbial community structure across fluid gradients in the Juan de Fuca Ridge <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, Rika E; Beltrán, Mónica Torres; Hallam, Steven J; Baross, John A</p> <p>2013-02-01</p> <p>Physical and chemical gradients are dominant factors in shaping <span class="hlt">hydrothermal</span> vent microbial ecology, where archaeal and bacterial habitats encompass a range between hot, reduced <span class="hlt">hydrothermal</span> fluid and cold, oxidized seawater. To determine the impact of these fluid gradients on microbial communities inhabiting these <span class="hlt">systems</span>, we surveyed bacterial and archaeal community structure among and between <span class="hlt">hydrothermal</span> plumes, diffuse flow fluids, and background seawater in several <span class="hlt">hydrothermal</span> vent sites on the Juan de Fuca Ridge using 16S rRNA gene diversity screening (clone libraries and terminal restriction length polymorphisms) and quantitative polymerase chain reaction methods. Community structure was similar between <span class="hlt">hydrothermal</span> plumes and background seawater, where a number of taxa usually associated with low-oxygen zones were observed, whereas high-temperature diffuse fluids exhibited a distinct phylogenetic profile. SUP05 and Arctic96BD-19 sulfur-oxidizing bacteria were prevalent in all three mixing regimes where they exhibited overlapping but not identical abundance patterns. Taken together, these results indicate conserved patterns of redox-driven niche partitioning between <span class="hlt">hydrothermal</span> mixing regimes and microbial communities associated with sinking particles and oxygen-deficient waters. Moreover, the prevalence of SUP05 and Arctic96BD-19 in plume and diffuse flow fluids indicates a more cosmopolitan role for these groups in the ecology and biogeochemistry of the dark ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21C1526C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21C1526C"><span>Investigation of Icelandic rift zones reveals systematic changes in <span class="hlt">hydrothermal</span> outflow in concert with seismic and magmatic events: Implications for investigation of Mid-Ocean Ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Curewitz, D.; Karson, J. A.</p> <p>2010-12-01</p> <p>Co-registration of several generations of geological data was carried out for <span class="hlt">hydrothermal</span> fields along active rift zones of the Iceland plate boundary zone. Significant short- and long-term changes in vent locations, flow rates and styles, and fluid characteristics over short periods take place in concert with recorded earthquakes, dike intrusions, and fissure eruptions. Higher resolution, more detailed analysis of the Icelandic <span class="hlt">hydrothermal</span> sites will inform investigation of similar data from mid-ocean ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> along the RIDGE 2000 focus sites. Initial results from the Hengill and Krafla geothermal areas covering a time-span of nearly 40 years at ~10 year intervals reveal limited changes in the surface expression of fault populations, with the exception of local fault and fracture <span class="hlt">systems</span>. The location and population density of individual vents and groups of vents underwent significant changes over the same time period, with either vents shifting location, or new vents opening and old vents closing. Registration of changes in vent fluid temperatures, vent field ground temperatures, fluid flow rates, and vent eruptive styles reveal changes in <span class="hlt">hydrothermal</span> flow systematics in concert with the observed changes in vent location and vent population density. Significant local seismic and volcanological events (earthquakes, earthquake swarms, dike intrusions, eruptions, inflation/deflation) that are potential triggers for the observed changes take place in intervening years between production of successive maps. Changes in modeled stress intensities and local fracture/fault density and geometry associated with these tectono-magmatic events correspond well to inferred locations of increased or decreased shallow permeability thought to control <span class="hlt">hydrothermal</span> outflow behavior. Recent seismic events are strongly linked to well-mapped changes in fracture/fault population and <span class="hlt">hydrothermal</span> flow behavior in the Hveragerdi region, near Hengill, and provide higher</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GGG....14.2084J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GGG....14.2084J"><span>Sulfide geochronology along the <span class="hlt">Endeavour</span> Segment of the 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 W.; Hannington, Mark D.; Clague, David A.; Kelley, Deborah S.; Delaney, John R.; Holden, James F.; Tivey, Margaret K.; Kimpe, Linda E.</p> <p>2013-07-01</p> <p>Forty-nine <span class="hlt">hydrothermal</span> sulfide-sulfate rock samples from the <span class="hlt">Endeavour</span> Segment of the Juan de Fuca Ridge, northeastern Pacific Ocean, were dated by measuring the decay of 226Ra (half-life of 1600 years) in <span class="hlt">hydrothermal</span> barite to provide a history of <span class="hlt">hydrothermal</span> venting at the site over the past 6000 years. This dating method is effective for samples ranging in age from ˜200 to 20,000 years old and effectively bridges an age gap between shorter- and longer-lived U-series dating techniques for <span class="hlt">hydrothermal</span> deposits. Results show that <span class="hlt">hydrothermal</span> venting at the active High Rise, Sasquatch, and Main <span class="hlt">Endeavour</span> fields began at least 850, 1450, and 2300 years ago, respectively. Barite ages of other inactive deposits on the axial valley floor are between ˜1200 and ˜2200 years old, indicating past widespread <span class="hlt">hydrothermal</span> venting outside of the currently active vent fields. Samples from the half-graben on the eastern slope of the axial valley range in age from ˜1700 to ˜2925 years, and a single sample from outside the axial valley, near the westernmost valley fault scarp is ˜5850 ± 205 years old. The spatial relationship between <span class="hlt">hydrothermal</span> venting and normal faulting suggests a temporal relationship, with progressive younging of sulfide deposits from the edges of the axial valley toward the center of the rift. These relationships are consistent with the inward migration of normal faulting toward the center of the valley over time and a minimum age of onset of <span class="hlt">hydrothermal</span> activity in this region of 5850 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3130K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3130K"><span>Volcano-<span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> of the Central and Northern Kuril Island Arc - a Review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalacheva, E.; Taran, Y.; Voloshina, E.; Ptashinsky, L.</p> <p>2015-12-01</p> <p>More than 20 active volcanoes with historical eruptions are known on 17 islands composing the Central and Northern part of the Kurilian Arc. Six islands - Paramushir, Shiashkotan, Rasshua, Ushishir, Ketoy and Simushir - are characterized by <span class="hlt">hydrothermal</span> activity, complementary to the fumarolic activity in their craters. There are several types of volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on the islands. At Paramushir, Shiashkotan and Ketoy the thermal manifestations are acidic to ultra-acidic water discharges associated with <span class="hlt">hydrothermal</span> aquifers inside volcano edifices and formed as the result of the absorption of magmatic gases by ground waters. A closest known analogue of such activity is Satsuma-Iwojima volcano-island at the Ryukyu Arc. Another type of <span class="hlt">hydrothermal</span> activity are wide spread coastal hot springs (Shiashkotan, Rasshua), situated as a rule within tide zones and formed by mixing of the heated seawater with cold groundwater or, in opposite, by mixing of the steam- or conductively heated groundwater with seawater. This type of thermal manifestation is similar to that reported for other volcanic islands of the world (Satsuma Iwojima, Monserrat, Ischia, Socorro). Ushishir volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> is formed by the absorption of magmatic gases by seawater. Only Ketoy Island hosts a permanent acidic crater lake. At Ebeko volcano (Paramushir) rapidly disappearing small acidic lakes (formed after phreatic eruptions) have been reported. The main <span class="hlt">hydrothermal</span> manifestation of Simushir is the Zavaritsky caldera lake with numerous coastal thermal springs and weak steam vents. The last time measured temperatures of fumaroles at the islands are: >500ºC at Pallas Peak (Ketoy), 480ºC at Kuntamintar volcano (Shiashkotan), variable and fast changing temperatures from 120º C to 500ºC at Ebeko volcano (Paramushir), 150ºC in the Rasshua crater, and > 300ºC in the Chirpoy crater (Black Brothers islands). The magmatic and rock-forming solute output by the Kurilian volcano-<span class="hlt">hydrothermal</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010IJAsB...9..137L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010IJAsB...9..137L"><span>Putative fossil life in a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of the Dellen impact structure, Sweden</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lindgren, Paula; Ivarsson, Magnus; Neubeck, Anna; Broman, Curt; Henkel, Herbert; Holm, Nils G.</p> <p>2010-07-01</p> <p>Impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are commonly proposed as good candidates for hosting primitive life on early Earth and Mars. However, evidence of fossil microbial colonization in impact-generated <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is rarely reported in the literature. Here we present the occurrence of putative fossil microorganisms in a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of the 89 Ma Dellen impact structure, Sweden. We found the putative fossilized microorganisms hosted in a fine-grained matrix of <span class="hlt">hydrothermal</span> alteration minerals set in interlinked fractures of an impact breccia. The putative fossils appear as semi-straight to twirled filaments, with a thickness of 1-2 μm, and a length between 10 and 100 μm. They have an internal structure with segmentation, and branching of filaments occurs frequently. Their composition varies between an outer and an inner layer of a filament, where the inner layer is more iron rich. Our results indicate that <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in impact craters could potentially be capable of supporting microbial life. This could have played an important role for the evolution of life on early Earth and Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.190...35G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.190...35G"><span>Molecular evidence for abiotic sulfurization of dissolved organic matter in marine shallow <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gomez-Saez, Gonzalo V.; Niggemann, Jutta; Dittmar, Thorsten; Pohlabeln, Anika M.; Lang, Susan Q.; Noowong, Ann; Pichler, Thomas; Wörmer, Lars; Bühring, Solveig I.</p> <p>2016-10-01</p> <p>Shallow submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are extreme environments with strong redox gradients at the interface of hot, reduced fluids and cold, oxygenated seawater. <span class="hlt">Hydrothermal</span> fluids are often depleted in sulfate when compared to surrounding seawater and can contain high concentrations of hydrogen sulfide (H2S). It is well known that sulfur in its various oxidation states plays an important role in processing and transformation of organic matter. However, the formation and the reactivity of dissolved organic sulfur (DOS) in the water column at <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are so far not well understood. We investigated DOS dynamics and its relation to the physicochemical environment by studying the molecular composition of dissolved organic matter (DOM) in three contrasting shallow <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> off Milos (Eastern Mediterranean), Dominica (Caribbean Sea) and Iceland (North Atlantic). We used ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the DOM on a molecular level. The molecular information was complemented with general geochemical data, quantitative dissolved organic carbon (DOC) and DOS analyses as well as isotopic measurements (δ2H, δ18O and F14C). In contrast to the predominantly meteoric fluids from Dominica and Iceland, <span class="hlt">hydrothermal</span> fluids from Milos were mainly fed by recirculating seawater. The <span class="hlt">hydrothermal</span> fluids from Milos were enriched in H2S and DOS, as indicated by high DOS/DOC ratios and by the fact that >90% of all assigned DOM formulas that were exclusively present in the fluids contained sulfur. In all three <span class="hlt">systems</span>, DOS from <span class="hlt">hydrothermal</span> fluids had on average lower O/C ratios (0.26-0.34) than surrounding surface seawater DOS (0.45-0.52), suggesting shallow <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> as a source of reduced DOS, which will likely get oxidized upon contact with oxygenated seawater. Evaluation of hypothetical sulfurization reactions suggests DOM reduction and sulfurization during seawater</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B22B..02A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B22B..02A"><span>Evolutionary strategies of cells and viruses in deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> revealed through comparative metagenomics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anderson, R.; Sogin, M. L.; Baross, J. A.</p> <p>2013-12-01</p> <p>The deep-sea <span class="hlt">hydrothermal</span> vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these <span class="hlt">systems</span> must also withstand these environmental extremes, and a high proportion of viruses in these <span class="hlt">systems</span> are lysogenic. Comparative analysis of a cellular and viral metagenome from a diffuse flow <span class="hlt">hydrothermal</span> vent has provided insights into the evolutionary strategies of both cells and viruses in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. We detected numerous mobile elements in the viral and cellular gene pools as well as a large number of prophage in the cellular fraction. We show that the <span class="hlt">hydrothermal</span> vent viral gene pool is relatively enriched in genes related to energy metabolism, a feature that is unique to the <span class="hlt">hydrothermal</span> vent viral gene pool compared to viral gene pools from other environments, indicating a potential for integrated prophage to enhance host metabolic flexibility. We also detected stronger purifying selection in the viral versus cellular gene pool, indicating selection pressures that promote prolonged viral integration in the host. Our results support the hypothesis that viruses enhance host genomic plasticity and adaptability in this extreme and dynamic environment. Finally, we will discuss general implications of this work for understanding the viral impact on biogeochemical cycles and evolutionary trajectories of microbial populations in the deep subsurface biosphere.</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://www.osti.gov/scitech/servlets/purl/887500','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/887500"><span>Conceptual geologic model and native state model of the Roosevelt Hot Springs <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Faulder, D.D.</p> <p>1991-01-01</p> <p>A conceptual geologic model of the Roosevelt Hot Springs <span class="hlt">hydrothermal</span> <span class="hlt">system</span> was developed by a review of the available literature. The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> consists of a meteoric recharge area in the Mineral Mountains, fluid circulation paths to depth, a heat source, and an outflow plume. A conceptual model based on the available data can be simulated in the native state using parameters that fall within observed ranges. The model temperatures, recharge rates, and fluid travel times are sensitive to the permeability in the Mineral Mountains. The simulation results suggests the presence of a magma chamber at depth as the likely heat source. A two-dimensional study of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> can be used to establish boundary conditions for further study of the geothermal reservoir.</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><span class="hlt">Hydrothermal</span> industrialization electric-power <span class="hlt">systems</span> 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 sites. (MHR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2261E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2261E"><span>Exploring an active <span class="hlt">hydrothermal</span> <span class="hlt">system</span> - An analogue study from the Swiss Alps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Egli, Daniel; Herwegh, Marco; Berger, Alfons; Baron, Ludovic</p> <p>2016-04-01</p> <p>Understanding the detailed flow paths in <span class="hlt">hydrothermal</span> reservoirs is crucial for successful exploration of naturally porous and permeable rock masses for energy production. However, due to the common inaccessibility of active <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of suitable depth, e.g. in the northern Alpine foreland of the European Alps, direct observations are normally impossible and the knowledge about such <span class="hlt">systems</span> is still insufficient. For that reason, a known fault-bound <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in the crystalline basement of the Aar Massif serves as an analogue for potential geothermal reservoirs in the deep crystalline subsurface of the northern Alpine foreland. During summer 2015, a 125 m hole has been drilled across this active <span class="hlt">hydrothermal</span> zone on the Grimsel Pass for in-situ characterization of its structural, petrophysical, mechanical as well as geophysical parameters. With this information, this project aims at improving the knowledge of natural <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> as a potentially exploitable energy source. The investigated <span class="hlt">system</span> is characterized by a central breccia zone surrounded by different types of cataclasites and localized high strain zones. The surrounding includes different altered and deformed granitoid host rocks. In this study, we focus on the ductile and brittle deformation (shear zones, fractures, joints) that provides the main fluid pathways. Their spatial distribution around a central water-bearing breccia zone as well as their continuity and permeability provide constraints on the water flow paths in such structurally controlled <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. The aim will be the connection of detailed structural data with petrophysical parameters such as porosities and permeabilities. The drillcore shows the high variability of deformation structures and related fluid pathways at different scales (millimeter-decameter) demonstrating the urgent need for an improved understanding of the link between mechanical evolution, associated deformation structures as well</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS059-05-007&hterms=red+shift&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dred%2Bshift','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS059-05-007&hterms=red+shift&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dred%2Bshift"><span>STS-59 red shift crew on <span class="hlt">Endeavour</span>'s middeck</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p>On <span class="hlt">Endeavour</span>'s middeck, the three sts-59 red shift crew members begin to organize what was believed to be among the longest mail messages in recent Shuttle history. With the picture held vertically, Astronaut Sidney M. Gutierrez, mission commander, is in upper right. Also seen are Astronauts Linda M. Godwin, payload commander, and Kevin P. Chilton, pilot. Though early Shuttle flights could brag of longer teleprinted messages, this Thermal Printing <span class="hlt">System</span>'s (TIPS) message from the ground competes with those of recent Shuttle flights.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994Geo....22...75W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994Geo....22...75W"><span>Mineralogy at the magma-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> interface in andesite volcanoes, 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>Wood, C. Peter</p> <p>1994-01-01</p> <p>Ejecta from phreatomagmatic eruptions of Ruapehu and White Island andesite volcanoes in New Zealand provide insight into the mineralogical reactions that occur when magma invades a vent-hosted <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. At the surface and in ejected blocks from shallow depths, <span class="hlt">hydrothermal</span> alteration mineralogies are dominated by silica polymorphs, anhydrite, natroalunite, and pyrite. Blocks from greater depths are composed mainly of cristobalite, anhydrite, halite, and magnetite. Where altered material was heated to magmatic temperatures, thermal decomposition reactions produced mullite, wollastonite, and indialite. Some ejected breccias contain osumilite, cordierite, sanidine, and hypersthene, indicative of reactions occurring near the osumilite-cordierite phase boundary at >800 °C and water pressure <0.2 kbar. Hedenbergite, wollastonite, andradite, and magnetite are found in rare skarn fragments, possibly formed by metasomatism of silica-poor, sulfate-rich <span class="hlt">hydrothermal</span> deposits. High- temperature parageneses of these types have not been reported before in shallow, acidic volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. However, they may be typical of the magma- <span class="hlt">hydrothermal</span> contact zone at many andesite volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/624049','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/624049"><span>CO{sub 2} supply from deep-sea <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></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> <span class="hlt">systems</span> are aimed as an on-site 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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> to the ocean may be significant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8069L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8069L"><span>Application of Hyperspectral Methods in <span class="hlt">Hydrothermal</span> Mineral <span class="hlt">System</span> Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laukamp, Carsten; Cudahy, Thomas; Gessner, Klaus; Haest, Maarten; Cacetta, Mike; Rodger, Andrew; Jones, Mal; Thomas, Matilda</p> <p>2010-05-01</p> <p> hyperspectral mineral mapping of contaminating, carbonate- or clay-rich zones helped to better constrain the ore zones and the genesis of the mineral <span class="hlt">system</span>. Airborne hyperspectral data covering about 2500 km2 were obtained from the Eastern Goldfields Superterrane (Yilgarn Craton, Western Australia), which is highly prospective for Archean Au as well as komatiite associated Fe-Ni sulphide mineralisation. In this project hyperspectral airborne data allowed not only the remote mapping of mafic and ultramafic rocks, which are among the main host rocks for Archean Au deposits in the study area, but also the remote mapping of <span class="hlt">hydrothermal</span> alteration patterns and various geochemical signatures related to the structurally controlled Au mineralisation down to a 4.5 m pixel size. We can reconstruct fluid pathways and their intersections with steep physicochemical gradients, where Au deposition presumably took place, by combining hyperspectral remote sensing with hyperspectral drill core data in 3D mineral maps. White mica mineral maps as well as mineral maps based on the abundance and composition of MgOH and FeOH bearing silicates are the main products for a semi-quantitative assessment of the key alteration minerals in this project. In the southern Selwyn Range, Mount Isa Inlier, Queensland, hyperspectral mineral maps, such as "ferric oxide abundance", "white mica abundance" and "white mica composition", were integrated with geophysical datasets (total magnetic intensity, ternary radiometric imagery). The integration of the datasets enabled us to construct a comprehensive fluid flow model contributing to our understanding of iron-oxide Cu-Au deposits in this region, identifying the source, pathway and depositional sites, which are in good accordance with known deposits. 3D mineral maps derived from hyperspectral methods can distinctly improve our understanding of mineral <span class="hlt">systems</span>. The advantages of hyperspectral techniques over conventional exploration methods include: (1) the fast and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=MSFC-9264290&hterms=japanese+women&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Djapanese%2Bwomen','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-9264290&hterms=japanese+women&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Djapanese%2Bwomen"><span>Space Shuttle Orbiter <span class="hlt">Endeavour</span> STS-47 Launch</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>A smooth countdown culminated in a picture-perfect launch as the Space Shuttle Orbiter <span class="hlt">Endeavour</span> (STS-47) climbed skyward atop a ladder of billowing smoke on September 12, 1992. The primary payload for the plarned seven-day flight was the Spacelab-J science laboratory. The second flight of <span class="hlt">Endeavour</span> marks a number of historic firsts: the first space flight of an African-American woman, the first Japanese citizen to fly on a Space Shuttle, and the first married couple to fly in space.</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>Organic Acids as Hetrotrophic Energy Sources in <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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 sites 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/2014EGUGA..1615834R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615834R"><span>Propidium Monoazide-based Method for Identifying Phylogenetic Association of Necromass Near <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramírez, Gustavo; Edwards, Katrina</p> <p>2014-05-01</p> <p>Black Smoker <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are geologically driven <span class="hlt">systems</span> located near subduction zones and spreading centers associated with plate margins. The high temperature and low pH of fluids that are often associated with basalt-hosted <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> select for unique microbial communities primarily comprised of prokaryotes capable of S and Fe cycling. High temperature fluids, where temperatures exceed 300° C, are likely to have a lethal effect on transient deep water planktonic communities and, over long temporal scales, may influence the molecular composition of pelleted necromass aggregates near the chimney <span class="hlt">system</span>. We have developed a method for discriminative sequencing permitting intra vs. extracellular 16S rDNA sequencing to reveal community differences between biologically-relevant and necromass-associated DNA. This method has only recently been applied to marine environments and, here, we propose its use as relevant tool for studying the molecular ecology of high temperature <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, as physical drivers of massive transient community die offs and associated detrital 16S rDNA community shifts. Ultimately, we aim to understand the fraction of 16S rDNA communities that do not represent living taxa, or the information-containing fraction of total necromass pool, to better frame ecological hypotheses regarding environmental biogeochemical cycling in <span class="hlt">hydrothermal</span> <span class="hlt">system</span> environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V21D..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V21D..04S"><span>Radiogenic Isotope Constraints on Fluid Sources in the Yellowstone <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, S. R.; Sims, K. W. W.; Role, A.; Shock, E.; Boyd, E. S.</p> <p>2015-12-01</p> <p>For decades, researchers in Yellowstone National Park (YNP) have used major and trace element and light stable isotope geochemistry to evaluate fluid sources and geochemical reactions in the Yellowstone <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. However, the results can be affected by mixing, boiling and vapor-phase separation. We present new strontium (Sr), neodymium (Nd), and lead (Pb) isotopic data from <span class="hlt">hydrothermal</span> waters and fumarole condensates that allow us to evaluate fluid sources independent of near-surface mixing and boiling. Our sample set was selected to explore the range of fluid compositions found in the Yellowstone <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, including waters/fluids that are thought to be exclusively meteoric, exclusively from the deep <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, and those which are a mixture of these end members and/or that have been influenced by various <span class="hlt">hydrothermal</span> processes such as boiling or gas/water interaction. We have identified at least three isotopic endmembers that persist in various features throughout the YNP <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. The first endmember has relatively unradiogenic Pb with Sr, Nd, and Pb isotopic compositions that are consistent with Yellowstone basalts and rhyolites. This endmember is typified by low pH features. We interpret this fluid as surface water and shallow groundwater that has interacted with volcanic rocks associated with the YNP magmatic <span class="hlt">system</span>, with the acidity derived from oxidation of volcanic gases. The second endmember has relatively radiogenic Pb, radiogenic Sr, and unradiogenic Nd. This endmember is typified by neutral pH features and near neutral fumarole condensates. We interpret this endmember to represent the hypothesized deep <span class="hlt">hydrothermal</span> reservoir that interacts with and reflects the isotopic composition of the host rock. The third endmember contains radiogenic Pb, unradiogenic Nd, and unradiogenic Sr. We observe this endmember in neutral features, which are interpreted as <span class="hlt">hydrothermal</span> waters (shallow, deep, or mixtures) that have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=MSFC-0302390&hterms=MBS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMBS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-0302390&hterms=MBS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMBS"><span>STS-111 Onboard Photo of <span class="hlt">Endeavour</span> Docking With PMA-2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>The STS-111 mission, the 14th Shuttle mission to visit the International Space Station (ISS), was launched on June 5, 2002 aboard the Space Shuttle Orbiter <span class="hlt">Endeavour</span>. On board were the STS-111 and Expedition Five crew members. Astronauts Kerneth D. Cockrell, commander; Paul S. Lockhart, pilot, and mission specialists Franklin R. Chang-Diaz and Philippe Perrin were the STS-111 crew members. Expedition Five crew members included Cosmonaut Valeri G. Korzun, commander, Astronaut Peggy A. Whitson and Cosmonaut Sergei Y. Treschev, flight engineers. Three space walks enabled the STS-111 crew to accomplish mission objectives: The delivery and installation of the Mobile Remote Servicer Base <span class="hlt">System</span> (MBS), an important part of the Station's Mobile Servicing <span class="hlt">System</span> that allows the robotic arm to travel the length of the Station, which is necessary for future construction tasks; the replacement of a wrist roll joint on the Station's robotic arm; and the task of unloading supplies and science experiments from the Leonardo multipurpose Logistics Module, which made its third trip to the orbital outpost. In this photograph, the Space Shuttle <span class="hlt">Endeavour</span>, back dropped by the blackness of space, is docked to the pressurized Mating Adapter (PMA-2) at the forward end of the Destiny Laboratory on the ISS. <span class="hlt">Endeavour</span>'s robotic arm is in full view as it is stretched out with the S0 (S-zero) Truss at its end.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=MSFC-0302391&hterms=MBS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMBS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-0302391&hterms=MBS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMBS"><span>STS-111 Onboard Photo of <span class="hlt">Endeavour</span> Docking With PMA-2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>The STS-111 mission, the 14th Shuttle mission to visit the International Space Station (ISS), was launched on June 5, 2002 aboard the Space Shuttle Orbiter <span class="hlt">Endeavour</span>. On board were the STS-111 and Expedition Five crew members. Astronauts Kerneth D. Cockrell, commander; Paul S. Lockhart, pilot, and mission specialists Franklin R. Chang-Diaz and Philippe Perrin were the STS-111 crew members. Expedition Five crew members included Cosmonaut Valeri G. Korzun, commander, Astronaut Peggy A. Whitson and Cosmonaut Sergei Y. Treschev, flight engineers. Three space walks enabled the STS-111 crew to accomplish the delivery and installation of the Mobile Remote Servicer Base <span class="hlt">System</span> (MBS), an important part of the Station's Mobile Servicing <span class="hlt">System</span> that allows the robotic arm to travel the length of the Station, which is necessary for future construction tasks; the replacement of a wrist roll joint on the Station's robotic arm; and the task of unloading supplies and science experiments from the Leonardo multipurpose Logistics Module, which made its third trip to the orbital outpost. In this photograph, the Space Shuttle <span class="hlt">Endeavour</span>, back dropped by the blackness of space, is docked to the pressurized Mating Adapter (PMA-2) at the forward end of the Destiny Laboratory on the ISS. A portion of the Canadarm2 is visible on the right and <span class="hlt">Endeavour</span>'s robotic arm is in full view as it is stretched out with the S0 (S-zero) Truss at its end.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70041332','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70041332"><span>Identifying bubble collapse in a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> using hiddden Markov models</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dawson, Phillip B.; Benitez, M.C.; Lowenstern, Jacob B.; Chouet, Bernard A.</p> <p>2012-01-01</p> <p>Beginning in July 2003 and lasting through September 2003, the Norris Geyser Basin in Yellowstone National Park exhibited an unusual increase in ground temperature and <span class="hlt">hydrothermal</span> activity. Using hidden Markov model theory, we identify over five million high-frequency (>15 Hz) seismic events observed at a temporary seismic station deployed in the basin in response to the increase in <span class="hlt">hydrothermal</span> activity. The source of these seismic events is constrained to within ~100 m of the station, and produced ~3500–5500 events per hour with mean durations of ~0.35–0.45 s. The seismic event rate, air temperature, hydrologic temperatures, and surficial water flow of the geyser basin exhibited a marked diurnal pattern that was closely associated with solar thermal radiance. We interpret the source of the seismicity to be due to the collapse of small steam bubbles in the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, with the rate of collapse being controlled by surficial temperatures and daytime evaporation rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1281062','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1281062"><span><span class="hlt">System</span> and process for efficient separation of biocrudes and water in a <span class="hlt">hydrothermal</span> liquefaction <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Oyler, James R.; Rotness, Jr, Leslie J.; Schmidt, Andrew J.; Zacher, Alan H.</p> <p>2016-08-02</p> <p>A <span class="hlt">system</span> and process are described for clean separation of biocrudes and water by-products from <span class="hlt">hydrothermal</span> liquefaction (HTL) product mixtures of organic and biomass-containing feedstocks at elevated temperatures and pressures. Inorganic compound solids are removed prior to separation of biocrude and water by-product fractions to minimize formation of emulsions that impede separation. Separation may be performed at higher temperatures that reduce heat loss and need to cool product mixtures to ambient. The present invention thus achieves separation efficiencies not achieved in conventional HTL processing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29034&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29034&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds"><span>Liftoff of STS-59 Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p>The liftoff of the Space Shuttle <span class="hlt">Endeavour</span> is backdropped against a dawn sky at the Kennedy Space Center (KSC). Trees and water from a nearby marsh outline the lower portion of the view. Liftoff occurred at 7:05 a.m., April 9, 1994.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29066&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29066&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds"><span>Liftoff of STS-59 Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p>The liftoff of the Space Shuttle <span class="hlt">Endeavour</span> is backdropped against clouds at the Kennedy Space Center (KSC). Liftoff occurred at 7:05 a.m., April 9, 1994. The air-to-air view was photographed from the Shuttle Training Aircraft (STA) piloted by astronaut Robert L. Gibson.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JVGR..189..172M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JVGR..189..172M"><span><span class="hlt">Hydrothermal</span> alteration in the Reykjanes geothermal <span class="hlt">system</span>: Insights from Iceland deep drilling program well RN-17</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marks, Naomi; Schiffman, Peter; Zierenberg, Robert A.; Franzson, Hjalti; Fridleifsson, Gudmundur Ó.</p> <p>2010-01-01</p> <p>The Reykjanes geothermal <span class="hlt">system</span> is a seawater-recharged <span class="hlt">hydrothermal</span> <span class="hlt">system</span> that appears to be analogous to seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in terms of host rock type and low water/rock alteration. The similarities make the Reykjanes <span class="hlt">system</span> a useful proxy for seafloor vents. At some time during the Pleistocene, the <span class="hlt">system</span> was dominated by meteoric water recharge, and fluid composition at Reykjanes has evolved through time as a result of changing proportions of meteoric water influx as well as differing pressure and temperature conditions. The purpose of this study is to characterize secondary mineralization, degree of metasomatic alteration, and bulk composition of cuttings from well RN-17 from the Reykjanes geothermal <span class="hlt">system</span>. The basaltic host rock includes hyaloclastite, breccia, tuff, extrusive basalt, diabase, as well as a marine sedimentary sequence. The progressive <span class="hlt">hydrothermal</span> alteration sequence observed with increasing depth results from reaction of geothermal fluids with the basaltic host rock. An assemblage of greenschist facies alteration minerals, including actinolite, prehnite, epidote and garnet, occurs at depths as shallow as 350 m; these minerals are commonly found in Icelandic geothermal <span class="hlt">systems</span> at temperatures above 250 °C (Bird and Spieler, 2004). This requires hydrostatic pressures that exceed the present-day depth to boiling point curve, and therefore must record alteration at higher fluid pressures, perhaps as a result of Pleistocene glaciation. Major, minor, and trace element profiles of the cuttings indicate transitional MORB to OIB composition with limited metasomatic shifts in easily mobilized elements. Changes in MgO, K 2O and loss on ignition indicate that metasomatism is strongly correlated with protolith properties. The textures of alteration minerals reveal alteration style to be strongly dependent on protolith as well. Hyaloclastites are intensely altered with calc-silicate alteration assemblages comprising calcic <span class="hlt">hydrothermal</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MinDe..52..383B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MinDe..52..383B"><span>A Palaeoproterozoic multi-stage <span class="hlt">hydrothermal</span> alteration <span class="hlt">system</span> 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>2017-03-01</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 site 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 <span class="hlt">system</span> 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/2016MinDe.tmp...36B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MinDe.tmp...36B"><span>A Palaeoproterozoic multi-stage <span class="hlt">hydrothermal</span> alteration <span class="hlt">system</span> 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 site 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 <span class="hlt">system</span> 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> </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://hdl.handle.net/2060/20080013258','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080013258"><span>Detection of Abiotic Methane in Terrestrial Continental <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span>: Implications for Methane on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.</p> <p>2008-01-01</p> <p>The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in <span class="hlt">hydrothermal</span> fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1512385H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1512385H"><span>Numerical 3D models support two distinct <span class="hlt">hydrothermal</span> circulation <span class="hlt">systems</span> 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; Theissen-Krah, Sonja; Rüpke, Lars</p> <p>2013-04-01</p> <p>We present 3D numerical calculations of <span class="hlt">hydrothermal</span> fluid flow at fast spreading ridges. The setup of the 3D models is based our previous 2D studies, in which we have coupled numerical models for crustal accretion and <span class="hlt">hydrothermal</span> fluid flow. One result of these calculations is a crustal permeability field that leads to a thermal structure in the crust that matches seismic tomography data of the East Pacific Rise (EPR). The 1000°C isotherm obtained from the 2D results is now used as the lower boundary of the 3D model domain, while the upper boundary is a smoothed bathymetry of the EPR. The same permeability field as in the 2D models is used, with the highest permeability at the ridge axis and a decrease with both depth and distance to the ridge. Permeability is also reduced linearly between 600 and 1000°C. Using a newly developed parallel finite element code written in Matlab that solves for thermal evolution, fluid pressure and Darcy flow, we simulate the flow patterns of <span class="hlt">hydrothermal</span> circulation in a segment of 5000m along-axis, 10000m across-axis and up to 5000m depth. We observe two distinct <span class="hlt">hydrothermal</span> circulation <span class="hlt">systems</span>: An on-axis <span class="hlt">system</span> forming a series of vents with a spacing ranging from 100 to 500m that is recharged by nearby (100-200m) downflows on both sides of the ridge axis. Simultaneously a second <span class="hlt">system</span> with much broader extensions both laterally and vertically exists off-axis. It is recharged by fluids intruding between 1500m to 5000m off-axis and sampling both upper and lower crust. These fluids are channeled in the deepest and hottest regions with high permeability and migrate up-slope following the 600°C isotherm until reaching the edge of the melt lens. Depending on the width of the melt lens these off-axis fluids either merge with the on-axis <span class="hlt">hydrothermal</span> <span class="hlt">system</span> or form separate vents. We observe separate off-axis vent fields if the magma lens half-width exceeds 1000m and confluence of both <span class="hlt">systems</span> for half-widths smaller than 500m. For</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11539452','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11539452"><span>Aqueous high-temperature and high-pressure organic geochemistry of <span class="hlt">hydrothermal</span> vent <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simoneit, B R</p> <p>1993-01-01</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> associated with oceanic spreading centers are now recognized as relatively common phenomena, and the organic chemical alterations occurring there are rapid and efficient. In the marine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at water depths > 1.5 km, the conditions driving chemical reactions are high temperatures (up to >400 degrees C), confining pressures (>150 bar), and other parameters such as pH, Eh, and mineralogy in an aqueous open flow medium. Continental <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may also be of interest, as, for example, in failed or dormant rifts and regions around piercement volcanoes. Organic matter alteration by reductive reactions to petroleum hydrocarbons occurs in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> over a wide temperature window (approximately 60 to >400 degrees C), under elevated pressure, and in a brief geological time (years to hundreds of years). The products are rapidly moved as bulk phase or in fluids from the regions at higher temperatures to areas at lower temperatures, where the high molecular weight material separates from the bulk. These conditions are conducive to organic chemistry which yields concurrent products by primarily reduction (due to mineral buffering), oxidation (high thermal stress), and synthesis reactions. This chemistry is just beginning to be elucidated by the geochemical community, but there are various industrial applications which provide useful preliminary insight. Therefore, the behavior of organic matter (inclusive of methane to high molecular weight compounds > C40) in warm to supercritical water needs to be characterized to understand the implications of this novel phenomenon in geological and geochemical processes, and the chemistry occurring over the full temperature spectrum of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is of relevance to origins of life research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.398..113A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.398..113A"><span>Microbial sulfate reduction within the Iheya North subseafloor <span class="hlt">hydrothermal</span> <span class="hlt">system</span> constrained by quadruple sulfur isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aoyama, Shinnosuke; Nishizawa, Manabu; Takai, Ken; Ueno, Yuichiro</p> <p>2014-07-01</p> <p>Subseafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> may host spatially extended and numerically abundant microbial communities sustained by sulfate reduction as one of the important terminal electron accepting metabolisms. In order to estimate microbial sulfate reduction in a subseafloor <span class="hlt">hydrothermal</span> regime, we analyzed sulfur isotopes (S32/S33/S34/S36) of pore-water sulfate and mineralized sulfide in the upper 100 m of sedimentary sequences at the Iheya North <span class="hlt">hydrothermal</span> field in the Okinawa Trough recovered in Integrated Ocean Drilling Program Expedition 331 (IODP Exp 331). On the basis of the pore water chemistry and temperature profiles, the subseafloor environment is divided into three hydrogeologic units. In the topmost Unit-1, relatively fresh seawater is recharged, and the bottommost Unit-3 is characterized by predominance of endmember-like high-temperature <span class="hlt">hydrothermal</span> fluid (>300 °C) underlying the impermeable cap rock layers. Intermediate Unit-2 is subject to mixing between the <span class="hlt">hydrothermal</span> fluid and seawater. The δ34S values of sulfate in the Unit-2 mixing zone were found to be more 34S-enriched than the values expected from simple mixing model of seawater sulfate in the Unit-1 with the <span class="hlt">hydrothermal</span> fluid in the Unit-3. The observed SSO434-enrichment and sulfate concentration [SO2-4]-depletion suggest sulfate reduction is taking place below the seafloor. Based on our model calculation, the isotope discrimination (ε34) is estimated to be -21‰. This large isotope discrimination together with slight Δ33S‧ enrichment and Δ36S‧ depletion reveals that sulfate reduction is caused by microbial processes but not by thermochemical processes. In addition, our numerical simulation points out that sulfate may be reduced prior to presently undergoing mixing with high-temperature fluid, probably within the seawater recharge zone. Despite the abundant input of <span class="hlt">hydrothermal</span> H2S, mineralized sulfide below 10 m seafloor (mbsf) shows characteristic sulfur isotopic signatures that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25575309','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25575309"><span>Energy landscapes shape microbial communities in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on the Arctic Mid-Ocean Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dahle, Håkon; Økland, Ingeborg; Thorseth, Ingunn H; Pederesen, Rolf B; Steen, Ida H</p> <p>2015-07-01</p> <p>Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> through an investigation of two geochemically different basalt-hosted <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on the Arctic Mid-Ocean Ridge: the Soria Moria Vent field (SMVF) and the Loki's Castle Vent Field (LCVF). Chemical energy landscapes were evaluated through modelling of the Gibbs energy from selected redox reactions under different mixing ratios between seawater and <span class="hlt">hydrothermal</span> fluids. Our models indicate that the sediment-influenced LCVF has a much higher potential for both anaerobic and aerobic methane oxidation, as well as aerobic ammonium and hydrogen oxidation, than the SMVF. The modelled energy landscapes were used to develop microbial community composition models, which were compared with community compositions in environmental samples inside or on the exterior of <span class="hlt">hydrothermal</span> chimneys, as assessed by pyrosequencing of partial 16S rRNA genes. We show that modelled microbial communities based solely on thermodynamic considerations can have a high predictive power and provide a framework for analyses of the link between energy availability and microbial community composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4478700','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4478700"><span>Energy landscapes shape microbial communities in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on the Arctic Mid-Ocean Ridge</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dahle, Håkon; Økland, Ingeborg; Thorseth, Ingunn H; Pederesen, Rolf B; Steen, Ida H</p> <p>2015-01-01</p> <p>Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> through an investigation of two geochemically different basalt-hosted <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on the Arctic Mid-Ocean Ridge: the Soria Moria Vent field (SMVF) and the Loki's Castle Vent Field (LCVF). Chemical energy landscapes were evaluated through modelling of the Gibbs energy from selected redox reactions under different mixing ratios between seawater and <span class="hlt">hydrothermal</span> fluids. Our models indicate that the sediment-influenced LCVF has a much higher potential for both anaerobic and aerobic methane oxidation, as well as aerobic ammonium and hydrogen oxidation, than the SMVF. The modelled energy landscapes were used to develop microbial community composition models, which were compared with community compositions in environmental samples inside or on the exterior of <span class="hlt">hydrothermal</span> chimneys, as assessed by pyrosequencing of partial 16S rRNA genes. We show that modelled microbial communities based solely on thermodynamic considerations can have a high predictive power and provide a framework for analyses of the link between energy availability and microbial community composition. PMID:25575309</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21C1518K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21C1518K"><span>Heat and chemical flux variability within the Main <span class="hlt">Endeavour</span> Field, Juan de Fuca Ridge, from 2000, 2004</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kellogg, J. P.; McDuff, R. E.; Hautala, S. L.; Stahr, F.</p> <p>2010-12-01</p> <p>The Main <span class="hlt">Endeavour</span> Field (MEF) has had a split personality since it was discovered. The southern half of the field is regularly observed to be hotter and fresher than the northern half. Differences lessened after the 1999 earthquake event, but the thermal and chemical gradient remains. We examine CTD and MAVS current meter data collected during surveys, designed to intersect the rising <span class="hlt">hydrothermal</span> plume, conducted with the Autonomous Benthic Explorer (ABE) in 2000 and 2004. By taking subsets of the data over known clusters of structures within the field, we attribute fractional contributions to the whole field heat and salt fluxes. Preliminary findings indicate that North MEF contributes ~90% and ~100% of the heat from MEF in 2000 and 2004 respectively. It is clear from this that the majority of the MEF buoyancy flux is from North MEF even though the source fluids from South MEF are estimated to be initially more buoyant than those from North MEF. Within North MEF, ~2/3 of the heat comes from the Grotto, Dante, Lobo sulfide cluster and ~1/4 from the Hulk and Crypto cluster. These data, for the intra-field spatial scales of heat and salt flux, may allow us to infer mechanisms capable of altering the porous network of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1975/0056/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1975/0056/report.pdf"><span>Preliminary hydrogeologic appraisal of selected <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in northern and central Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Olmsted, F.H.; Glancy, P.A.; Harrill, J.R.; Rush, F.E.; Van Denburgh, A.S.</p> <p>1975-01-01</p> <p>Several <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in northern and central Nevada were explored in a hydrogeologic reconnaissance. The <span class="hlt">systems</span> studied comprise those at Stillwater and Soda Lakes-Upsal Hogback in the Carson Desert, Gerlach, Fly Ranch-Granite Range, and Double Hot Springs in the Black Rock Desert, Brady's Hot Springs, Leach Hot Springs in Grass Valley, Buffalo Valley Hot Springs, and Sulphur Hot Springs in Ruby Valley. The investigation focused on (1) delineating of areas of high heat flow associated with rising thermal ground water, (2) determining the nature of the discharge parts of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, (3) estimating heat discharge from the <span class="hlt">systems</span>, (4) estimating water discharge from the <span class="hlt">systems</span>, (5) obtaining rough estimates of, conductive heat flow outside areas of <span class="hlt">hydrothermal</span> discharge, and (6) evaluating several investigative techniques that would yield the required information quickly and at relatively low cost. The most useful techniques were shallow test drilling to obtain geologic, hydraulic, and thermal data and hydrogeologic mapping of the discharge areas. The <span class="hlt">systems</span> studied are in the north-central part of the Basin and Range province. Exposed volcanic rocks of latest Tertiary and Quaternary age are chiefly basaltic. Basaltic terranes are generally regarded as less favorable for geothermal resources than terranes that contain large volumes of young volcanic mocks of felsic to intermediate composition. Most of the known <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are associated with Basin and Range faults which are caused by crustal extension across the province. An area of high heat flow centered at Battle Mountain and possibly other areas of high heat flow may be related to crustal heat sources. However, some of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> studied appear to be related to deep circulation of meteoric water in areas of 'normal' regional heat flow rather than to shallow-crustal heat sources. Discharge temperatures of thermal springs in the region range from slightly above mean</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3139K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3139K"><span>Delineating Spatial Patterns in the Yellowstone <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> using Geothermometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>King, J.; Hurwitz, S.; Lowenstern, J. B.</p> <p>2015-12-01</p> <p>Yellowstone National Park is unmatched with regard to its quantity of active <span class="hlt">hydrothermal</span> features. Origins of thermal waters in its geyser basins have been traced to mixing of a deep parent water with meteoric waters in shallow local reservoirs (Fournier, 1989). A mineral-solution equilibrium model was developed to calculate water-rock chemical re-equilibration temperatures in these shallow reservoirs. We use the GeoT program, which uses water composition data as input to calculate saturation indices of selected minerals; the "best-clustering" minerals are then statistically determined to infer reservoir temperatures (Spycher et al., 2013). We develop the method using water composition data from Heart Lake Geyser Basin (HLGB), for which both chemical and isotopic geothermometers predict a reservoir water temperature of 205°C ± 10°C (Lowenstern et al., 2012), and minerals found in drill cores in Yellowstone's geyser basins. We test the model for sensitivity to major element composition, pH, Total Inorganic Carbon (TIC) and selected minerals to optimize model parameters. Calculated temperatures are most accurate at pH values below 9.0, and closely match the equilibrium saturation indices of quartz, stilbite, microcline, and albite. The model is optimized with a TIC concentration that is consistent with the mass of diffuse CO2 flux in HLGB (Lowenstern et al., 2012). We then use water compositions from other thermal basins in Yellowstone in search of spatial variations in reservoir temperatures. We then compare the calculated temperatures with various SiO2 and cation geothermometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26154881','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26154881"><span>RNA Oligomerization in Laboratory Analogues of Alkaline <span class="hlt">Hydrothermal</span> Vent <span class="hlt">Systems</span>.</span></a></p> <p><a target="_blank" href="https://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 sites 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 site 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150019437','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150019437"><span>The Degradational History of <span class="hlt">Endeavour</span> Crater, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, J. A.; Parker, T. J.; Crumpler, L. S.; Wilson, S. A.; Golombek, M. P.; Mittlefehldt, D. W.</p> <p>2015-01-01</p> <p><span class="hlt">Endeavour</span> crater (2.28 deg S, 354.77 deg E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in Meridiani Planum. The degradation state of the crater has been studied using Mars Reconnaissance Orbiter and Opportunity rover data. Exposed rim segments rise approximately 10 m to approximately 100 m above the level of the embaying Burns Formation and the crater is 200-500 m deep with the southern interior wall exposing over approximately 300 m relief. Both pre-impact rocks (Matijevic Formation) and <span class="hlt">Endeavour</span> impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker crops out (up to approximately 140 m) along the rim segment from Murray Ridge to Cape Tribulation. Study of pristine complex craters Bopolu and Tooting, and morphometry of other martian complex craters, enables us to approximate <span class="hlt">Endeavour</span>'s pristine form. The original rim likely averaged 410 m (+/-)200 m in elevation and a 250-275 m section of ejecta ((+/-)50-60 m) would have composed a significant fraction of the rim height. The original crater depth was likely between 1.5 km and 2.2 km. Comparison between the predicted original and current form of <span class="hlt">Endeavour</span> suggests approximately 100-200 m rim lowering that removed most ejecta in some locales (e.g., Cape York) while thick sections remain elsewhere (e.g., Cape Tribulation). Almost complete removal of ejecta at Cape York and minimal observable offset across fractures indicates current differences in rim relief are not solely due to original rim relief. Rim segments are embayed by approximately 100-200 m thickness of plains rocks outside the crater, but thicker deposits lie inside the crater. Ventifact textures confirm ongoing eolian erosion with the overall extent difficult to estimate. Analogy with degraded Noachian-aged craters south of <span class="hlt">Endeavour</span>, however, suggests fluvial erosion dominated rim degradation in the Noachian and was likely followed by approximately 10s of meters modification by alternate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B12A0747B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B12A0747B"><span><span class="hlt">Endeavour</span> Segment, Juan de Fuca Ridge, Integrated Studies Site (ISS) Update and Opportunities</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Butterfield, D.; Ridge Community</p> <p>2003-12-01</p> <p>The Ridge 2000 (R2K) Integrated Studies bull's eye on the Juan de Fuca Ridge is focused on the Main <span class="hlt">Endeavour</span> <span class="hlt">hydrothermal</span> field, located on the central portion of the <span class="hlt">Endeavour</span> Segment. This vent field is one of the most vigorously venting <span class="hlt">systems</span> along the global mid-ocean ridge spreading network, hosting at least 18 large sulfide structures that contains more than100 smokers. Prior to a magmatic event in 2000 some of the edifices had been venting 380C, volatile-rich fluids with extremely low chlorinities for a decade. In addition to the Main <span class="hlt">Endeavour</span> Field there are four other known high temperature vent fields spaced approximately 2 kilometers apart along the segment (with hints of more) and abundant areas of diffuse flow, both nearby and distal to the high temperature venting. Diffuse flow from the structures and from a variety of basaltic-hosted sites provides rich habitats abundant with microbial and macrofaunal communities. There are well-developed gradients in volatile concentrations along axis that may reflect influence from a sedimentary source to the north, and high chlorinity fluids vent from the most southern (Mothra) and northern fields (Sasquatch). Twenty years of research have laid a firm base for the 5-year plans of R2K at this site, which include examining the response of this segment to perturbations induced by tectonic and magmatic events, identification of the reservoirs, fluxes, and feedbacks of mass and energy at this site, and predictive modeling coupled with field observations. Since designation as an IS site, high-resolution bathymetric mapping (EM300) and an extensive multi-channel seismic survey have been conducted along the entire segment. Smaller focused areas have also been mapped at meter resolution by SM2000 sonar. Intense field programs in 2003 established the first in-situ seismic array along a mid-ocean ridge, which includes installation of a buried broadband seismometer and 7 short-period seismometers emplaced within basaltic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024124','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024124"><span>Helium and carbon gas geochemistry of pore fluids from the sediment-rich <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in Escanaba Trough</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ishibashi, J.-I.; Sato, M.; Sano, Y.; Wakita, H.; Gamo, T.; Shanks, Wayne C.</p> <p>2002-01-01</p> <p>Ocean Drilling Program (ODP) Leg 169, which was conducted in 1996 provided an opportunity to study the gas geochemistry in the deeper part of the sediment-rich <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in Escanaba Trough. Gas void samples obtained from the core liner were analyzed and their results were compared with analytical data of vent fluid samples collected by a submersible dive program in 1988. The gas geochemistry of the pore fluids consisted mostly of a <span class="hlt">hydrothermal</span> component and was basically the same as that of the vent fluids. The He isotope ratios (R/RA = 5.6-6.6) indicated a significant mantle He contribution and the C isotopic compositions of the hydrocarbons [??13C(CH4) = -43???, ??13C(C2H6) = -20???] were characterized as a thermogenic origin caused by <span class="hlt">hydrothermal</span> activity. On the other hand, the pore fluids in sedimentary layers away from the <span class="hlt">hydrothermal</span> fields showed profiles which reflected lateral migration of the <span class="hlt">hydrothermal</span> hydrocarbons and abundant biogenic CH4. Helium and C isotope systematics were shown to represent a <span class="hlt">hydrothermal</span> component and useful as indicators for their distribution beneath the seafloor. Similarities in He and hydrocarbon signatures to that of the Escanaba Trough <span class="hlt">hydrothermal</span> <span class="hlt">system</span> were found in some terrestrial natural gases, which suggested that seafloor <span class="hlt">hydrothermal</span> activity in sediment-rich environments would be one of the possible petroleum hydrocarbon generation scenarios in unconventional geological settings. ?? 2002 Elsevier Science Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986JGR....91.1867H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986JGR....91.1867H"><span><span class="hlt">Hydrothermal</span> alteration in the Baca Geothermal <span class="hlt">System</span>, Redondo Dome, Valles Caldera, New Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hulen, Jeffrey B.; Nielson, Dennis L.</p> <p>1986-02-01</p> <p>Thermal fluids circulating in the active <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of the resurgent Redondo dome of the Valles caldera have interacted with their diverse host rocks to produce well-zoned alteration assemblages, which not only help locate permeable fluid channels but also provide insight into the <span class="hlt">system</span>'s thermal history. The alteration shows that fluid flow has been confined principally to steeply dipping normal faults and subsidiary fractures as well as thin stratigraphic aquifers. Permeability along many of these channels has been reduced or locally eliminated by <span class="hlt">hydrothermal</span> self-sealing. Alteration from the surface through the base of the Miocene Paliza Canyon Formation is of three distinctive types: argillic, propylitic, and phyllic. Argillic alteration forms a blanket above the deep water table in formerly permeable nonwelded tuffs. Beneath the argillic zone, pervasive propylitic alteration is weakly developed in felsic host rocks but locally intense in deep intermediate composition volcanics. Strong phyllic alteration is commonly but not invariably associated with major active thermal fluid channels. Phyllic zones yielding no fluid were clearly once permeable but now are <span class="hlt">hydrothermally</span> sealed. High-temperature alteration phases at Baca are presently found at much lower temperatures. We suggest either that isotherms have collapsed due to gradual cooling of the <span class="hlt">system</span>, that they have retreated without overall heat loss due to uplift of the Redondo dome, that the <span class="hlt">system</span> has shifted laterally, or that it has contracted due to a drop in the water table. The deepest Well (B-12, 3423 m) in the dome may have penetrated through the base of the active <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Below a depth of 2440 m in this well, <span class="hlt">hydrothermal</span> veining largely disappears, and the rocks resemble those developed by isochemical thermal metamorphism. The transition is reflected by temperature logs, which show a conductive thermal gradient below 2440 m. This depth may mark the dome's neutral plane</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616710Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616710Y"><span>Dynamic drivers of a shallow-water <span class="hlt">hydrothermal</span> vent ecogeochemical <span class="hlt">system</span> (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>Shallow-water <span class="hlt">hydrothermal</span> vents share many characteristics with their deep-sea analogs. However, despite ease of access, much less is known about the dynamics of these <span class="hlt">systems</span>. Here, we report on the spatial and temporal chemical variability of a shallow-water vent <span class="hlt">system</span> at Paleochori Bay, Milos Island, Greece, and on the bacterial and archaeal diversity of associated sandy sediments. Our multi-analyte voltammetric profiles of dissolved O2 and <span class="hlt">hydrothermal</span> tracers (e.g. Fe2+, FeSaq, Mn2+) on sediment cores taken along a transect in <span class="hlt">hydrothermally</span> affected sediments indicate three different areas: the central vent area (highest temperature) with a deeper penetration of oxygen into the sediment, and a lack of dissolved Fe2+ and Mn2+; a middle area (0.5 m away) rich in dissolved Fe2+ and Mn2+ (exceeding 2 mM) and high free sulfide with potential for microbial sulfide oxidation as suggested by the presence of white mats at the sediment surface; and, finally, an outer rim area (1-1.5 m away) with lower concentrations of Fe2+ and Mn2+ and higher signals of FeSaq, indicating an aged <span class="hlt">hydrothermal</span> fluid contribution. In addition, high-frequency temperature series and continuous in situ H2S measurements with voltammetric sensors over a 6-day time period at a distance 0.5 m away from the vent center showed substantial temporal variability in temperature (32 to 46 ºC ) and total sulfide (488 to 1329 µM) in the upper sediment layer. Analysis of these data suggests that tides, winds, and abrupt geodynamic events generate intermittent mixing conditions lasting for several hours to days. Despite substantial variability, the concentration of sulfide available for chemoautotrophic microbes remained high. These findings are consistent with the predominance of Epsilonproteobacteria in the <span class="hlt">hydrothermally</span> influenced sediments Diversity and metagenomic analyses on sediments and biofilm collected along a transect from the center to the outer rim of the vent provide further insights on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..173..217F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..173..217F"><span>Chemical transport in geothermal <span class="hlt">systems</span> in Iceland: Evidence from <span class="hlt">hydrothermal</span> alteration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franzson, Hjalti; Zierenberg, Robert; Schiffman, Peter</p> <p>2008-06-01</p> <p>This study focuses on the chemical changes in basaltic rocks in fossil low- and high-temperature <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in Iceland. The method used takes into account the amount of dilution caused by vesicle and vein fillings in the rocks. The amount of dilution allows a calculation of the primary concentration of the immobile element Zr, and by multiplying the composition of the altered rock by the ratio of Zr (protolith)/Zr (altered rock) one can compute the mass addition caused by the dilution of the void fillings, and also make a direct comparison with the likely protoliths from the same areas. The samples were divided into three groups; two from Tertiary fossil high-temperature <span class="hlt">systems</span> (Hafnarfjall, Geitafell), and the third group from a low temperature, zeolite-altered plateau basalt succession. The results show that <span class="hlt">hydrothermally</span> altered rocks are enriched in Si, Al, Fe, Mg and Mn, and that Na, K and Ca are mobile but show either depletion or enrichment. The elements that are immobile include Zr, Y, Nb and probably Ti. The two high-temperature <span class="hlt">systems</span> show quite similar chemical alteration trends, an observation which may apply to Icelandic fresh water high-temperature <span class="hlt">systems</span> in general. The geochemical data show that the major changes in the altered rocks from Icelandic geothermal <span class="hlt">systems</span> may be attributed to addition of elements during deposition of pore-filling alteration minerals. A comparison with seawater-dominated basalt-hosted <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> shows much greater mass flux within the seawater <span class="hlt">systems</span>, even though both <span class="hlt">systems</span> have similar alteration assemblages. The secondary mineral assemblages seem to be controlled predominantly by the thermal stability of the alteration phases and secondarily by the composition of the <span class="hlt">hydrothermal</span> fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70073974','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70073974"><span>Ancient aqueous environments at <span class="hlt">Endeavour</span> crater, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Arvidson, R. E.; Squyres, S. W.; Bell, J.F.; Catalano, J.G.; Clark, B. C.; Crumpler, L.S.; de Souza, P.A.; Fairén, A.G.; Farrand, W. H.; Fox, V.K.; Gellert, Ralf; Ghosh, A.; Golombeck, M.P.; Grotzinger, J.P.; Guinness, E.A.; Herkenhoff, Kenneth E.; Jolliff, B.L.; Knoll, A.H.; Li, R.; McLennan, S.M.; Ming, D. W.; Mittlefehldt, D. W.; Moore, Johnnie N.; Morris, R.V.; Murchie, S.L.; Parker, T.J.; Paulsen, G.; Rice, J.W.; Ruff, S.W.; Smith, M.D.; Wolff, M.J.</p> <p>2014-01-01</p> <p>Opportunity has investigated in detail rocks on the rim of the Noachian age <span class="hlt">Endeavour</span> crater, where orbital spectral reflectance signatures indicate the presence of Fe+3-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the <span class="hlt">Endeavour</span> impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24458648','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24458648"><span>Ancient aqueous environments at <span class="hlt">Endeavour</span> crater, Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arvidson, R E; Squyres, S W; Bell, J F; Catalano, J G; Clark, B C; Crumpler, L S; de Souza, P A; Fairén, A G; Farrand, W H; Fox, V K; Gellert, R; Ghosh, A; Golombek, M P; Grotzinger, J P; Guinness, E A; Herkenhoff, K E; Jolliff, B L; Knoll, A H; Li, R; McLennan, S M; Ming, D W; Mittlefehldt, D W; Moore, J M; Morris, R V; Murchie, S L; Parker, T J; Paulsen, G; Rice, J W; Ruff, S W; Smith, M D; Wolff, M J</p> <p>2014-01-24</p> <p>Opportunity has investigated in detail rocks on the rim of the Noachian age <span class="hlt">Endeavour</span> crater, where orbital spectral reflectance signatures indicate the presence of Fe(+3)-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the <span class="hlt">Endeavour</span> impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1775&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1775&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss"><span>STS-97 <span class="hlt">Endeavour</span> after RSS rollback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>Against a cloudless blue sky, Space Shuttle <span class="hlt">Endeavour</span> stands ready for launch after the rollback of the Rotating Service Structure, at left. <span class="hlt">Endeavour</span> is targeted for launch tonight at about 10:06 p.m. EST on mission STS-97 to the International Space Station. The orbiter carries the P6 Integrated Truss Segment containing solar arrays that will be temporarily installed to the Unity connecting module by the Z1 truss, recently delivered to and installed on the Station on mission STS-92. The two solar arrays are each more than 100 feet long. They will capture energy from the sun and convert it to power for the Station. Two spacewalks will be required to install the solar array connections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20140013897&hterms=rice&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Drice','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20140013897&hterms=rice&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Drice"><span>Ancient Aqueous Environments at <span class="hlt">Endeavour</span> Crater, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arvidson, R. E.; Squyres, S. W.; Bell, J. F.; Catalano, J. G.; Clark, B. C.; Crumpler, L. S.; de Souza, P. A.; Fairen, A. G.; Farrand, W. H.; Fox, V. K.; Gellert, R.; Ghosh, A.; Golombek, M. P.; Grotzinger, J. P.; Guinness, E. A.; Herkenhoff, K. E.; Jolliff, B. L.; Knoll, A. H.; Li, R.; McLennan, S. M.; Ming, D. W.; Mittlefehldt, D. W.; Moore, J. M.; Morris, R. V.; Murchie, S. L.; Parker, T. J.; Paulsen, G.; Rice, J. W.; Ruff, S. W.; Smith, M. D.; Wolff, M. J.</p> <p>2014-01-01</p> <p>Opportunity has investigated in detail rocks on the rim of the Noachian age <span class="hlt">Endeavour</span> crater, where orbital spectral reflectance signatures indicate the presence of Fe(+3)-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the <span class="hlt">Endeavour</span> impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Sci...343G.386A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Sci...343G.386A"><span>Ancient Aqueous Environments at <span class="hlt">Endeavour</span> Crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arvidson, R. E.; Squyres, S. W.; Bell, J. F.; Catalano, J. G.; Clark, B. C.; Crumpler, L. S.; de Souza, P. A.; Fairén, A. G.; Farrand, W. H.; Fox, V. K.; Gellert, R.; Ghosh, A.; Golombek, M. P.; Grotzinger, J. P.; Guinness, E. A.; Herkenhoff, K. E.; Jolliff, B. L.; Knoll, A. H.; Li, R.; McLennan, S. M.; Ming, D. W.; Mittlefehldt, D. W.; Moore, J. M.; Morris, R. V.; Murchie, S. L.; Parker, T. J.; Paulsen, G.; Rice, J. W.; Ruff, S. W.; Smith, M. D.; Wolff, M. J.</p> <p>2014-01-01</p> <p>Opportunity has investigated in detail rocks on the rim of the Noachian age <span class="hlt">Endeavour</span> crater, where orbital spectral reflectance signatures indicate the presence of Fe+3-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the <span class="hlt">Endeavour</span> impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-96PC-0706&hterms=PAMs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPAMs','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-96PC-0706&hterms=PAMs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPAMs"><span>STS-77 <span class="hlt">Endeavour</span> Launch (side view closeup)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1996-01-01</p> <p>A flawless countdown culminates with an on-time liftoff as the Space Shuttle <span class="hlt">Endeavour</span> lights up the morning sky. <span class="hlt">Endeavour</span> was launched on Mission STS-77 from Pad 39B at 6:30:00 a.m. EDT, May 19. The fourth Shuttle mission of 1996 is devoted to the continuing effort to help open the commercial space frontier. Heading up the six-member crew is Commander John H. Casper. Curtis L. Brown Jr. is the pilot and there are four mission specialists on board: Daniel W. Bursch, Mario Runco Jr., Andrew S. W. Thomas and Marc Garneau, who represents the Canadian Space Agency. During the approximately 10-day mission, the astronauts will perform a variety of payload activities, including microgravity research aboard the SPACEHAB-4 module, deployment and retrieval of the Spartan 207 carrying the Inflatable Antenna Experiment (IAE) and deployment and rendezvous with the Passive Aerodynamically-Stabilized Magnetically-Damped Satellite (PAMS).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-96PC-0707&hterms=PAMs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPAMs','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-96PC-0707&hterms=PAMs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPAMs"><span>STS-77 <span class="hlt">Endeavour</span> Launch (below SRB closeup)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1996-01-01</p> <p>A flawless countdown culminates with an on-time liftoff as the Space Shuttle <span class="hlt">Endeavour</span> lights up the morning sky. <span class="hlt">Endeavour</span> was launched on Mission STS-77 from Pad 39B at 6:30:00 a.m. EDT, May 19. The fourth Shuttle mission of 1996 is devoted to the continuing effort to help open the commercial space frontier. Heading up the six-member crew is Commander John H. Casper. Curtis L. Brown Jr. is the pilot and there are four mission specialists on board: Daniel W. Bursch, Mario Runco Jr., Andrew S. W. Thomas and Marc Garneau, who represents the Canadian Space Agency. During the approximately 10-day mission, the astronauts will perform a variety of payload activities, including microgravity research aboard the SPACEHAB-4 module, deployment and retrieval of the Spartan 207 carrying the Inflatable Antenna Experiment (IAE) and deployment and rendezvous with the Passive Aerodynamically-Stabilized Magnetically-Damped Satellite (PAMS).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.B31A0955A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.B31A0955A"><span>Microbial arsenic oxidation in a shallow marine <span class="hlt">hydrothermal</span> vent <span class="hlt">system</span></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.; Meyer-Dombard, D. R.; Pichler, T.; Price, R.; Herndon, E.; Hsia, N.</p> <p>2005-12-01</p> <p>The toxic effects of arsenic are well documented, but this Group V element can also serve as an energy source to a diverse group of microorganisms. Most of the attention has been on arsenate (AsV) reduction, but the focus is shifting to include arsenite (AsIII) oxidation and subsequent immobilization through coprecipitation with iron (oxy)hydroxides. The shallow marine <span class="hlt">hydrothermal</span> fluids near Ambitle Island, Papua New Guinea are characterized by arsenite concentrations of up to 1,000 μg/L. Directly proximal to the vent orifices, arsenate coprecipitates with 2-line ferrihydrite, coating rocks and corals in red and green biofilms up to 1 cm thick. DNA extracted from these coatings was amplified with archaeal- and bacterial-specific primers, and the 16S rRNA gene was sequenced. Both biofilm samples revealed archaeal communities exclusively composed of uncultured Crenarchaea. The bacterial members are primarily gamma Proteobacteria and Planctomycetes in the red biofilm, but 60% of the community in the green biofilm affiliate with the alpha Proteobacteria and candidate group OP11; there is minimal overlap in bacterial phylotypes between the two coatings. Slurries from these coatings were also used to inoculate geochemically designed growth media supplemented with various redox couples, including aerobic and anaerobic As(III) oxidation. On a medium targeting anaerobic, chemolithoautotrophic arsenic oxidation coupled to ferric iron reduction at 50 °C, predominantly rod-shaped organisms (~5×105 cells/ml) were enriched. In contrast, on an aerobic arsenic oxidation medium, coccoid-shaped organisms (~3×106 cells/ml) were enriched. The respective thermophilic microbial communities may be taking advantage of overall metabolisms represented by H3AsO3(aq) + 2FeOOH(s) + 3H+ = H2AsO4- + 2Fe2+ + 3H2O (1) and H3AsO3(aq) + 1/2O2(aq) = H2AsO4- + H+. (2) To date, no arsenite oxidizers are known to use ferric iron as a terminal electron acceptor (reaction 1). However, this</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>Dynamic typology of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: 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> <span class="hlt">systems</span> relies on recognition of (i) <span class="hlt">hydrothermal</span> fluid source, (ii) fluid migration pathways, and (iii) deposition site 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 site), 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 <span class="hlt">system</span> 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 site, (ii) magnitude of disequilibrium at inflow to the mineralization site, which is related to physico-chemical gradient between the fluid source and the mineralization site, and (iii) chemical redistribution (dispersion) within the mineralization site. We introduce quantitative mass-transport descriptors - Péclet and Damköhler II numbers - to introduce division into dispersion-dominated, advection-dominated and reaction-constrained <span class="hlt">systems</span>. Dispersive <span class="hlt">systems</span> are characterized by lateral solute redistribution, driven by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993xmm..pres...53.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993xmm..pres...53."><span><span class="hlt">Endeavour</span> returns from Hubble servicing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>1993-12-01</p> <p>During the hour-long descent from space ESA astronaut Claude Nicollier helped mission commander Dick Covey and pilot Ken Bowersox monitor the shuttle's cockpit displays. During their 11-day mission the astronauts fitted the telescope with corrective optics and a new set of European solar panels. If all goes according to plan the observatory will be restored to very nearly its original capability. The first images from the rejuvenated telescope should be released in about 6-8 weeks. ESA had a major role in this mission. In addition to providing the solar arrays, the European Space Agency helped NASA test the Costar corrective optics <span class="hlt">system</span>. ESA astronaut Claude Nicollier operated the shuttle's robot arm throughout the complex spacewalks to service the telescope and during the crucial capture and release phases. "This was a particularly important international mission from the standpoint of our Swiss and European Space Agency crew member Claude Nicollier, who played an incredibly important part in the repair of the Hubble Space Telescope", mission commander Dick told Swiss Minister of Internal Affairs Mrs Ruth Dreifuss, during a VIP telephone call on Sunday morning. "If there was an unsung hero of this mission it would be Claude and his arm because without them we could not have worked the way we did and been as successful as we were".</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000027618&hterms=fur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dfur','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000027618&hterms=fur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dfur"><span>STS-99 / <span class="hlt">Endeavour</span> Mission Overview</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>The primary objective of the STS-99 mission was to complete high resolution mapping of large sections of the Earth's surface using the Shuttle Radar Topography Mission (SRTM). This radar <span class="hlt">system</span> will produce unrivaled 3-D images of the Earth's Surface. This videotape presents a mission overview press briefing. The panel members are Dr. Ghassem Asrar, NASA Associate Administrator Earth Sciences; General James C. King, Director National Imagery and Mapping Agency (NIMA); Professor Achim Bachem, Member of the Executive Board, Deutschen Zentrum fur Luft- und Raumfahrt (DLR), the German National Aerospace Research Center; and Professor Sergio Deiulio, President of the Italian Space Agency. Dr. Asrar opened with a summary of the history of Earth Observations from space, relating the SRTM to this history. This mission, due to cost and complexity, required partnership with other agencies and nations, and the active participation of the astronauts. General King spoke to the expectations of NIMA, and the use of the Synthetic Aperture Radar to produce the high resolution topographic images. Dr. Achim Bachem spoke about the international cooperation that this mission required, and some of the commercial applications and companies that will use this data. Dr Deiulio spoke of future plans to improve knowledge of the Earth using satellites. Questions from the press concerned use of the information for military actions, the reason for the restriction on access to the higher resolution data, the mechanism to acquire that data for scientific research, and the cost sharing from the mission's partners. There was also discussion about the mission's length.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29109&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS059%28S%29109&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ds"><span>Liftoff of STS-59 Shuttle <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p>The Space Shuttle <span class="hlt">Endeavour</span> heads for its sixth mission in space. Liftoff occurred at 7:05 a.m., April 9, 1994. This photograph was taken by Karen Dillon of San Jose, California, who observed the liftoff from the NASA causeway. It shows the orbiter as a bright spot at the top of a trail of smoke, with the water from a nearby marsh in the foreground.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP13A1136C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP13A1136C"><span>Magnetic mapping of submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at Marsili and Palinuro volcanoes from deep-towed magnetometer data</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.; Bortoluzzi, G.; Carmisciano, C.; Cocchi, L.; de Ronde, C. E.; Ligi, M.; Muccini, F.</p> <p>2013-12-01</p> <p>We collected near-bottom magnetic data at Marsili and Palinuro volcanoes in the Southern Tyrrhenian Sea, by adding a magnetometer to a deep-towed sidescan sonar. Equivalent magnetization maps obtained by inversion of the recorded magnetic anomalies are analyzed to map alteration zones related to <span class="hlt">hydrothermal</span> processes and are correlated with water-column and seafloor observations of <span class="hlt">hydrothermal</span> activity. At Marsili volcano, we found a large elliptical area of low magnetization, confirming the existence of a large <span class="hlt">hydrothermal</span> <span class="hlt">system</span> located in proximity of the top cone, above the magma chamber. Palinuro volcano is characterized by <span class="hlt">hydrothermal</span> venting located along the caldera walls, where the corresponding ring faults may provide preferred pathways for the upflow of the <span class="hlt">hydrothermal</span> fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..325...15S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..325...15S"><span>Resistivity structure and geochemistry of the Jigokudani Valley <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, Mt. Tateyama, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seki, Kaori; Kanda, Wataru; Tanbo, Toshiya; Ohba, Takeshi; Ogawa, Yasuo; Takakura, Shinichi; Nogami, Kenji; Ushioda, Masashi; Suzuki, Atsushi; Saito, Zenshiro; Matsunaga, Yasuo</p> <p>2016-10-01</p> <p>This study clarifies the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Jigokudani Valley near Mt. Tateyama volcano in Japan by using a combination of audio-frequency magnetotelluric (AMT) survey and hot-spring water analysis in order to assess the potential of future phreatic eruptions in the area. Repeated phreatic eruptions in the area about 40,000 years ago produced the current valley morphology, which is now an active solfatara field dotted with hot springs and fumaroles indicative of a well-developed <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. The three-dimensional (3D) resistivity structure of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> was modeled by using the results of an AMT survey conducted at 25 locations across the valley in 2013-2014. The model suggests the presence of a near-surface highly conductive layer of < 50 m in thickness across the entire valley, which is interpreted as a cap rock layer. Immediately below the cap rock is a relatively resistive body interpreted as a gas reservoir. Field measurements of temperature, pH, and electrical conductivity (EC) were taken at various hot springs across the valley, and 12 samples of hot-spring waters were analyzed for major ion chemistry and H2O isotopic ratios. All hot-spring waters had low pH and could be categorized into three types on the basis of the Cl-/SO 42 - concentration ratio, with all falling largely on a mixing line between magmatic fluids and local meteoric water (LMW). The geochemical analysis suggests that the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> includes a two-phase zone of vapor-liquid. A comparison of the resistivity structure and the geochemically inferred structure suggests that a <span class="hlt">hydrothermal</span> reservoir is present at a depth of approximately 500 m, from which hot-spring water differentiates into the three observed types. The two-phase zone appears to be located immediately beneath the cap rock structure. These findings suggest that the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Jigokudani Valley exhibits a number of factors that could trigger a future phreatic eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3129T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3129T"><span>Geochemistry of the Koshelev Volcano-<span class="hlt">Hydrothermal</span> <span class="hlt">System</span>, Southern Kamchatka, Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taran, Y.; Kalacheva, E.</p> <p>2015-12-01</p> <p>Koshelev is the southernmost volcano of the Kamchatkan volcanic front where magmatic plumbing <span class="hlt">systems</span> of the Kamchatkan subduction zone cross a thick layer of the oil-gas-bearing Neogene sedimentary strata of Western Kamchatka. The volcanic massive hosts a powerful <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, which has been drilled in early 1980s. Deep wells tapped a hot (ca. 300ºC) saline solution (up to 40 g/L of Cl), whereas the upper part of the <span class="hlt">system</span> is a typical steam cap with temperature close to 240ºC. Two <span class="hlt">hydrothermal</span> fields of the volcano (Upper and Lower) discharge saturated or super-heated (up to 150ºC) steam and are characterized by numerous hot pools and low flow-rate springs of steam-heated waters enriched in boron and ammonia. There is also a small lateral group of warm Na-Ca-Cl-SO4 springs (40ºC). We report here our data and review the literature geochemical data on the chemical and isotopic composition of waters and <span class="hlt">hydrothermal</span> vapours of the Koshelev <span class="hlt">system</span>. Data on the gas composition include He and C isotopes, as well as the chemical and isotopic composition of light hydrocarbons. Water geochemistry includes literature data on water isotopes of the deep brine and trace elements and REE of steam-heated waters. A conceptual model of the <span class="hlt">system</span> is presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/491864','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/491864"><span>Field-based tests of geochemical modeling codes: New Zealand <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.</p> <p>1993-12-01</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/60846','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/60846"><span>Field-based tests of geochemical modeling codes using New Zealand <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.</p> <p>1994-06-01</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/347708','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/347708"><span>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> associated with the Kilauea East Rift Zone, Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thomas, D.M.; Conrad, M.E.</p> <p>1997-12-31</p> <p>During the last twenty years drilling and fluid production on the Kilauea East Rift Zone (KERZ) has shown that an active <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is associated with much of the rift. Well logging and fluid geochemistry indicate that reservoir temperatures exceed 360 C but are highly variable. Although neither well testing nor pressure decline data have clearly demonstrated the lateral limits of the reservoir, divergent fluid compositions over short distances suggest that the larger <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is strongly compartmentalized across the rift zone. The chemical compositions of production fluids indicate that recharge is derived from ocean water and meteoric recharge and isotopic data suggest that the latter may be derived from subsurface inflow from the flanks of Mauna Loa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/815537','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/815537"><span>Using toughreact to model reactive fluid flow and geochemical transport in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten</p> <p>2003-07-31</p> <p>The interaction between <span class="hlt">hydrothermal</span> fluids and the rocks through which they migrate alters the earlier formed primary minerals and leads to the formation of secondary minerals, resulting in changes in the physical and chemical properties of the <span class="hlt">system</span>. We have developed a comprehensive numerical simulator, TOUGHREACT, which considers nonisothermal multi-component chemical transport in both liquid and gas phases. A variety of subsurface thermo-physical-chemical processes is considered under a wide range of conditions of pressure, temperature, water saturation, and ionic strength. The code can be applied to problems in fundamental analysis of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and in the exploration of geothermal reservoirs including chemical evolution, mineral alteration, mineral scaling, changes of porosity and permeability, and mineral recovery from geothermal fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018464','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018464"><span>Hydrogen isotope systematics of phase separation in submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: Experimental calibration and theoretical models</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Berndt, M.E.; Seal, R.R.; Shanks, Wayne C.; Seyfried, W.E.</p> <p>1996-01-01</p> <p>Hydrogen isotope fractionation factors were measured for coexisting brines and vapors formed by phase separation of NaCl/H2O fluids at temperatures ranging from 399-450??C and pressures from 277-397 bars. It was found that brines are depleted in D compared to coexisting vapors at all conditions studied. The magnitude of hydrogen isotope fractionation is dependent on the relative amounts of Cl in the two phases and can be empirically correlated to pressure using the following relationship: 1000 ln ??(vap-brine) = 2.54(??0.83) + 2.87(??0.69) x log (??P), where ??(vap-brine) is the fractionation factor and ??P is a pressure term representing distance from the critical curve in the NaCl/H2O <span class="hlt">system</span>. The effect of phase separation on hydrogen isotope distribution in subseafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> depends on a number of factors, including whether phase separation is induced by heating at depth or by decompression of <span class="hlt">hydrothermal</span> fluids ascending to the seafloor. Phase separation in most subseafloor <span class="hlt">systems</span> appears to be a simple process driven by heating of seawater to conditions within the two-phase region, followed by segregation and entrainment of brine or vapor into a seawater dominated <span class="hlt">system</span>. Resulting vent fluids exhibit large ranges in Cl concentration with no measurable effect on ??D. Possible exceptions to this include <span class="hlt">hydrothermal</span> fluids venting at Axial and 9??N on the East Pacific Rise. High ??D values of low Cl fluids venting at Axial are consistent with phase separation taking place at relatively shallow levels in the oceanic crust while negative ??D values in some low Cl fluids venting at 9??N suggest involvement of a magmatic fluid component or phase separation of D-depleted brines derived during previous <span class="hlt">hydrothermal</span> activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714343J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714343J"><span>Seismic tomography and dynamics of geothermal and natural <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the south of Bandung, Indonesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jousset, Philippe; Sule, Rachmat; Diningrat, Wahyuddin; Syahbana, Devy; Schuck, Nicole; Akbar, Fanini; Kusnadi, Yosep; Hendryana, Andri; Nugraha, Andri; Ryannugroho, Riskiray; Jaya, Makki; Erbas, Kemal; Bruhn, David; Pratomo, Bambang</p> <p>2015-04-01</p> <p>The structure and the dynamics of geothermal reservoirs and <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> allows us to better assess geothermal resources in the south of Bandung. A large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and <span class="hlt">hydrothermal</span> processes in this area. We deployed a geophysical network around geothermal areas starting with a network of 30 seismic stations including high-dynamic broadband Güralp and Trillium sensors (0.008 - 100 Hz) and 4 short-period (1 Hz) sensors from October 2012 to December 2013. We extended the network in June 2013 with 16 short-period seismometers. Finally, we deployed a geodetic network including a continuously recording gravity meter, a GPS station and tilt-meters. We describe the set-up of the seismic and geodetic networks and we discuss observations and results. The earthquakes locations were estimated using a non-linear algorithm, and revealed at least 3 seismic clusters. We perform joint inversion of hypo-center and velocity tomography and we look at seismic focal mechanisms. We develop seismic ambient noise tomography. We discuss the resulting seismic pattern within the area and relate the structure to the distribution of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. We aim at searching possible structural and dynamical links between different <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. In addition, we discuss possible dynamical implications of this complex volcanic <span class="hlt">systems</span> from temporal variations of inferred parameters. The integration of those results allows us achieving a better understanding of the structures and the dynamics of those geothermal reservoirs. This approach contributes to the sustainable and optimal exploitation of the geothermal resource in Indonesia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T31A0490K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T31A0490K"><span>Repeat Hydrography at the <span class="hlt">Endeavour</span> Integrated Study Site, 2004 - 2005</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kellogg, J. P.; McDuff, R. E.; Thomson, R. E.; Stahr, F. R.</p> <p>2005-12-01</p> <p>Significant differences exist between hydrographic transects made in 2004 and 2005 at the <span class="hlt">Endeavour</span> Segment Integrated Study Site on the Juan de Fuca Ridge. Sections that describe the conditions above the segment utilize twenty-one nearly uniformly spaced hydrographic stations from south of Mothra to north of the Sasquatch <span class="hlt">hydrothermal</span> vent fields. Criteria used in choosing station locations included depth, ~500 m spacing from other stations, and being centrally located in the valley. The resulting sections allow for rapid evaluation of the characteristics of the neutrally buoyant plume over each of the vent fields. Preliminary results indicate heat content over the northern vent fields, Salty Dawg and Sasquatch, significantly increased between the summers of 2004 and 2005. In 2004, the plumes over these vent fields were barely discernable while in 2005 prominent plumes existed with potential temperature anomalies over 0.1°C. Vent data being obtained by other RIDGE 2000 and UW Keck investigators will help constrain the underlying causes of these changes. Isopycnals in the 2005 sections are also elevated along the entire length of the transect by approximately 50 m or more. The potential temperature anomaly section from 2005 is indicative of a thicker (about 75 m) neutrally buoyant plume and substantially more heat at the north end of the valley. In 2004, the shallowest plume depth was 1900 m contrasted with 1830 m in 2005.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5139708','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5139708"><span>Comparative assessment of five potential sites for <span class="hlt">hydrothermal</span>-magma <span class="hlt">systems</span>: energy transport</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hardee, H.C.</p> <p>1980-09-01</p> <p>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 <span class="hlt">hydrothermal</span>-magma <span class="hlt">system</span>, 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-<span class="hlt">hydrothermal</span> transport <span class="hlt">system</span>: the magma zone, the <span class="hlt">hydrothermal</span> 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 <span class="hlt">systems</span>. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.441...26F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.441...26F"><span>Origin of magnetic highs at ultramafic hosted <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: Insights from the Yokoniwa site of Central 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>Fujii, Masakazu; Okino, Kyoko; Sato, Taichi; Sato, Hiroshi; Nakamura, Kentaro</p> <p>2016-05-01</p> <p>High-resolution vector magnetic measurements were performed on an inactive ultramafic-hosted <span class="hlt">hydrothermal</span> vent field, called Yokoniwa <span class="hlt">Hydrothermal</span> 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 <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> sites of the Mid-Atlantic Ridge. The results of rock magnetic analysis on seafloor rock samples (including basalt, dolerite, gabbro, serpentinized peridotite, and <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, strongly magnetized magnetite and pyrrhotite form during the progression of <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Furthermore, the results highlight the use of near-seafloor magnetic field measurements as a powerful tool for detecting and characterizing seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4117188','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4117188"><span>Biosphere frontiers of subsurface life in the sedimented <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Guaymas Basin</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; Callaghan, Amy V.; LaRowe, Douglas E.</p> <p>2014-01-01</p> <p>Temperature is one of the key constraints on the spatial extent, physiological and phylogenetic diversity, and biogeochemical function of subsurface life. A model <span class="hlt">system</span> to explore these interrelationships should offer a suitable range of geochemical regimes, carbon substrates and temperature gradients under which microbial life can generate energy and sustain itself. In this theory and hypothesis article, we make the case for the <span class="hlt">hydrothermally</span> heated sediments of Guaymas Basin in the Gulf of California as a suitable model <span class="hlt">system</span> where extensive temperature and geochemical gradients create distinct niches for active microbial populations in the <span class="hlt">hydrothermally</span> influenced sedimentary subsurface that in turn intercept and process <span class="hlt">hydrothermally</span> generated carbon sources. We synthesize the evidence for high-temperature microbial methane cycling and sulfate reduction at Guaymas Basin – with an eye on sulfate-dependent oxidation of abundant alkanes – and demonstrate the energetic feasibility of these latter types of deep subsurface life in previously drilled Guaymas Basin locations of Deep-Sea Drilling Project 64. PMID:25132832</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.V41B1389T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V41B1389T"><span><span class="hlt">Hydrothermal</span> circulation <span class="hlt">system</span> in the central Mariana illustrated by Magnetometoric Resistivity experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tada, N.; Seama, N.; Goto, T.; Kido, M.</p> <p>2004-12-01</p> <p><span class="hlt">Hydrothermal</span> vent fields are known to exist on the spreading axis, where sea water penetrates into the crust and upwells through the <span class="hlt">hydrothermal</span> vents. Understanding of the <span class="hlt">hydrothermal</span> circulation <span class="hlt">system</span> is extremely important to reveal the cooling process of the oceanic crust. The thermal structure beneath the <span class="hlt">hydrothermal</span> vent reflects the extent of underground activity and the convection scale of the hot water. Temperature in the crust can be estimated from the electrical conductivity because the conductivity depends on the water volume, the salinity concentration and the temperature of the sea water in the crust. The Alice Spring Field (18 o12.9'N, 144 o42.5'E and 3600m deep), on the spreading axis in the central Mariana Back-Arc Basin, is a suitable site for this purpose. <span class="hlt">Hydrothermal</span> vent in this field was firstly discovered by Alvin in 1987 (Hawkins et al., 1990). Shinkai6500 also confirmed the <span class="hlt">hydrothermal</span> activity in 1992 and 1996 (Gamou et al., 1994; Fujikura et al., 1997). In November, 2002, we conducted Magnetometric Resistivity (MMR) survey using R/V Kairei, JAMSTEC in this field. In the MMR method, controlled electric current was applied from a pair of electrodes; one is just beneath the sea surface and the other is close to the seafloor. To record electoromagnetic responses of the crust to the inputed current, we deployed six ocean bottom electromagnetometers (OBEMs), which can measure 3-components of magnetic and electric fields simultaneously. Measurements were conducted at 34 sites around the field, each of which consists of 30 minutes stacking for repeated current signals to keep better S/N ratio. Apparent resistivity is given by a function of amplitudes of magnetic field variation and source-receiver distance. We recovered the data from four OBEMs (two were on the spreading axis and other two were off axis). The plot of magnetic amplitudes to source-receiver distances shows different trend between OBEMs on-axis and off-axis. Therefore, we</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/890518','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/890518"><span>Deep Borehole Measurements for Characterizing the Magma/<span class="hlt">Hydrothermal</span> <span class="hlt">System</span> 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 site 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 <span class="hlt">system</span>. 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> <span class="hlt">system</span> in the caldera fill. To achieve this will require careful logging of borehole fluid temperature and chemistry. In addition, studies of rock/fluid interactions through core and fluid samples will allow physical characterization of the transition zone between <span class="hlt">hydrothermal</span> and magmatic regimes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1776&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1776&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss"><span>STS-97 <span class="hlt">Endeavour</span> after RSS rollback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>After rollback of the Rotating Service Structure (at left), Space Shuttle <span class="hlt">Endeavour</span> stands ready for launch targeted for 10:06 p.m. EST tonight on mission STS-97 to the International Space Station. The orbiter carries the P6 Integrated Truss Segment containing solar arrays that will be temporarily installed to the Unity connecting module by the Z1 truss, recently delivered to and installed on the Station on mission STS-92. The two solar arrays are each more than 100 feet long. They will capture energy from the sun and convert it to power for the Station. Two spacewalks will be required to install the solar array connections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Icar..280...22G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Icar..280...22G"><span>The degradational history of <span class="hlt">Endeavour</span> crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grant, J. A.; Parker, T. J.; Crumpler, L. S.; Wilson, S. A.; Golombek, M. P.; Mittlefehldt, D. W.</p> <p>2016-12-01</p> <p><span class="hlt">Endeavour</span> crater (2.28°S, 354.77°E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in southern Meridiani Planum. The degradation state of the crater has been studied using orbital data from the Mars Reconnaissance Orbiter and in situ data from the Opportunity rover. Multiple exposed crater rim segments range in elevation from ∼10 m to over 100 m above the level of the embaying Burns Formation. The crater is 200-500 m deep and the interior wall exposes over ∼300 m of relief around the southern half of the crater. Slopes of 6-16% flank the exterior of the largest western rim segment. On the west side of the crater, both pre-impact rocks (Matijevic Formation) and <span class="hlt">Endeavour</span> impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker Formation (up to ∼140 m section) outcrops at Cape Tribulation. Study of similar sized pristine craters Bopolu and Tooting (with complex morphology) and use of metrics for describing the morphometry of martian craters suggest the original rim of <span class="hlt">Endeavour</span> averaged 410 m in elevation, but relief varied about ±200 m around the circumference. A 250-275 m section of ejecta (±50-60 m) would have comprised a significant fraction of the rim height. The original crater was likely 1.5-2.2 km deep and may have had a central peak (no obvious evidence is present) between 200 and 500 m high. Comparison between the predicted original and current form of <span class="hlt">Endeavour</span> suggests 100-200 m of rim degradation ranging from nearly complete ejecta removal in some locations to preservation of a thick ejecta section in others. Differences in rim relief are at least partially due to degradation and not just original rim relief and (or) due to offsets along rim faults. Most degradation occurred prior to deposition of the Burns Formation which is ∼200 m thick outside the crater, but likely thicker inside the crater. Aeolian stripping of the Burns Formation continues today via prevailing winds and lesser mass</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-95PC-1032&hterms=1032&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D1032','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-95PC-1032&hterms=1032&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D1032"><span>STS-69 crew outside <span class="hlt">Endeavour</span> during TCDT</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1995-01-01</p> <p>STS-69 crew members wear broad smiles as they pose for a group photograph outside the crew hatch of the Space Shuttle <span class="hlt">Endeavour</span>. The crew is participating in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for the launch targetd for Aug. 5. From left, are Mission Commander David M. Walker; Mission Specialists Michael L. Gernhardt and James H. Newman; Payload Commander James S. Voss and Pilot Kenneth D. Cockrell. Primary objectives of the mission are the deployment, retrieval and operation of the Wake Shield Facility (WSF) satellite on its second flight and the SPARTAN-201 spacecraft which is making its third flight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5419S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5419S"><span>Post-impact <span class="hlt">hydrothermal</span> <span class="hlt">system</span> geochemistry and mineralogy: Rochechouart impact structure, France.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simpson, Sarah</p> <p>2014-05-01</p> <p>Hypervelocity impacts generate extreme temperatures and pressures in target rocks and may permanently alter them. The process of cratering is at the forefront of research involving the study of the evolution and origin of life, both on Mars and Earth, as conditions may be favourable for <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to form. Of the 170 known impact structures on Earth, over one-third are known to contain fossil <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> [1]. The introduction of water to a <span class="hlt">system</span>, when coupled with even small amounts of heat, has the potential to completely alter the target or host rock geochemistry. Often, the mineral assemblages produced in these environments are unique, and are useful indicators of post-impact conditions. The Rochechouart impact structure in South-Central France is dated to 201 ± 2 Ma into a primarily granitic target [2]. Much of the original morphological features have been eroded and very little of the allochthonous impactites remain. This has, however, allowed researchers to study the shock effects on the lower and central areas of the structure, as well as any subsequent <span class="hlt">hydrothermal</span> activity. Previous work has focused on detailed classification of the target and autochthonous and allochthonous impactites [3, 4], identification of the projectile [5], and dating the structure using Ar-isotope techniques [2]. Authors have also noted geochemical evidence of K-metasomatism, which is pronounced throughout all lithologies as enrichment in K2O and depletion in CaO and Na2O [3, 4, 5]. This indicates a pervasive <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, whose effects throughout the structure have yet to be studied in detail, particularly in those parts at and below the transient floor. The purpose of this study is to classify the mineralogical and geochemical effects of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Samples were collected via permission from the Réserve Naturelle de l'Astroblème de Rochechouart-Chassenon [6]. Sample selection was based on the presence of secondary mineralization in hand</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V52B..06G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V52B..06G"><span><span class="hlt">Hydrothermal</span> REE and Zr Ore Forming Processes in Peralkaline Granitic <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gysi, A. P.</p> <p>2015-12-01</p> <p>Anorogenic peralkaline igneous <span class="hlt">systems</span> display extreme enrichment of REE and Zr with a <span class="hlt">hydrothermal</span> overprint leading to post-magmatic metal mobilization. Strange Lake in Canada, for example, is a mid-Proterozoic peralkaline granitic intrusion and host to a world-class REE-Zr deposit with >50 Mt ore (>1.5 wt.% REE and >3 wt.% Zr). In contrast to porphyry <span class="hlt">systems</span>, peralkaline <span class="hlt">systems</span> are poorly understood and <span class="hlt">hydrothermal</span> metal mobilization models are only in the early stage of their development. This is partly due to the paucity of thermodynamic data for REE-bearing minerals and aqueous species, and the complexity of the <span class="hlt">hydrothermal</span> fluids (enrichment of F, P and Cl), which make it difficult to develop thermodynamic models of metal partitioning. This study aims to show the link between alteration stages and metal mobilization using Strange Lake as a natural laboratory and combine these observations with numerical modeling. Four types of alteration were recognized at Strange Lake: i) alkali (i.e. K and Na) metasomatism related to interaction with NaCl-bearing orthomagmatic fluids, ii) acidic alteration by HCl-HF-bearing fluids originating from the pegmatites followed by iii) aegirinization of the border of the pegmatites and surrounding granites and by iv) pervasive Ca-F-metasomatism. The acidic alteration accounts for most of the <span class="hlt">hydrothermal</span> metal mobilization in and outward from the pegmatites, whereas the Ca-F-metasomatism led to metal deposition and resulted from interaction of an acidic F-rich fluid with a Ca-bearing fluid. Numerical simulations of fluid-rock reactions with saline HCl-HF-bearing fluids at 400 °C to 250 °C indicate that temperature, availability of F/Cl and pH limit the mobility of Zr and REE. Fluids with pH <2 led to the formation of quartz and fluorite in the core of the pegmatites and to an increase in the stability of REE chloride species favorable for REE mobilization. The mobilization of Zr was favored at low temperature with the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V32B..06C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V32B..06C"><span><span class="hlt">Hydrothermal</span> mineralogy and fluid inclusions chemistry to understand the roots of active geothermal <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chambefort, I. S.; Dilles, J. H.; Heinrich, C.</p> <p>2013-12-01</p> <p>An integrated study to link magmatic textures, magmatic mineral compositions, <span class="hlt">hydrothermal</span> alteration zoning, <span class="hlt">hydrothermal</span> mineral chemistry, and fluid inclusion compositions has been undertaken to link an intrusive complex and its degassing alteration halo with their surface equivalent in an active geothermal <span class="hlt">system</span>. Ngatamariki geothermal <span class="hlt">system</span>, New Zealand, presents a unique feature in the Taupo Volcanic Zone (TVZ). Drilling intercepted an intrusive complex with a high temperature alteration halo similarly to what is observed in magmatic-derived ore deposits. Thus it presents the perfect opportunity to study the magmatic-<span class="hlt">hydrothermal</span> transition of the TVZ by characterizing the nature of the deep magmatic fluids link to the heat source of the world known geothermal fields. The record of magmatic-<span class="hlt">hydrothermal</span> fluid-rock interactions preserved at Ngatamariki may be analogous of processes presently occurring at depth beneath TVZ geothermal <span class="hlt">systems</span>. The intrusive complex consists of over 5 km3 of tonalite, diorite, basalt and aplitic dykes. Evidence of undercooling subsolidus magmatic textures such as myrmekite and skeletal overgrowth are commonly observed and often linked to volatile loss. The fluids released during the crystallization of the intrusive complex are interpreted to be at the origin of the surrounding high temperature alteration halo. Advanced argillic to potassic alteration and high temperature acidic assemblage is associated with high-temperature quartz veining at depth and vuggy silica at the paleo-surface. Major element compositions of the white micas associated with the high temperature halo show a transition from, muscovite to phengite, muscovitic illite away from the intrusion, with a transition to pyrophyllite and/ or topaz, and andalusite characteristic of more acidic conditions. Abundant high-density (up to 59 wt% NaCl eq and homogenization temperatures of 550 degree Celsius and above) coexist with low-density vapor fluid inclusions. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JIEIB..98...35J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JIEIB..98...35J"><span>Group Search Optimization for Fixed Head <span class="hlt">Hydrothermal</span> Power <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jena, Chitralekha; Basu, Mousumi</p> <p>2017-02-01</p> <p>This paper presents group search optimization for optimal scheduling of thermal plants in coordination with fixed head hydro units. Numerical results for two test <span class="hlt">systems</span> have been presented to demonstrate the performance of the proposed method. Results obtained from the proposed group search optimization method have been compared with those obtained from differential evolution and evolutionary programming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012514','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012514"><span>A review of numerical simulation of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mercer, J.W.; Faust, C.R.</p> <p>1979-01-01</p> <p>Many advances in simulating single and two-phase fluid flow and heat transport in porous media have recently been made in conjunction with geothermal energy research. These numerical models reproduce <span class="hlt">system</span> thermal and pressure behaviour and can be used for other heat-transport problems, such as high-level radioactive waste disposal and heat-storage projects. -Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JIEIB.tmp....3J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JIEIB.tmp....3J"><span>Group Search Optimization for Fixed Head <span class="hlt">Hydrothermal</span> Power <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jena, Chitralekha; Basu, Mousumi</p> <p>2016-05-01</p> <p>This paper presents group search optimization for optimal scheduling of thermal plants in coordination with fixed head hydro units. Numerical results for two test <span class="hlt">systems</span> have been presented to demonstrate the performance of the proposed method. Results obtained from the proposed group search optimization method have been compared with those obtained from differential evolution and evolutionary programming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V53A1745J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V53A1745J"><span>Fossil Magmatic-<span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> in Pleistocene Brokeoff Volcano, Lassen Volcanic National Park, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>John, D. A.; Breit, G. N.; Lee, R. G.; Dilles, J. H.; Muffler, L. P.; Clynne, M. A.</p> <p>2006-12-01</p> <p>The mineralogy, distribution, and isotopic composition of altered rocks exposed in the core of Brokeoff Volcano are attributed to two fossil magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> that are partly masked by younger alteration related to modern hot springs. Brokeoff Volcano was a large andesitic volcano (~600 to 400 ka) that preceded formation of Lassen Peak and the Lassen dome field. The two centers of fossil <span class="hlt">hydrothermal</span> activity are about 1 km apart and are identified here as the Brokeoff Mountain (BM) and Mt. Diller (MD) <span class="hlt">systems</span>. The BM <span class="hlt">system</span>, centered about 1 km NE of Brokeoff Mountain, covers about 1.5 km2 extending 2.5 km west from Diamond Peak, through Sulphur Works, to west of the ridge between Brokeoff Mountain and Mt. Diller. Alteration affected mostly andesite lavas and breccias of the Mill Canyon sequence (~600-475 ka). Core alteration extends westward and upward from an altered andesite plug exposed west of Sulphur Works. It consists of narrow, west-trending, brecciated vuggy silica ledges as long as 600 m surrounded by zones of variable thickness (<1 to 30 m) composed of alunite, kaolinite, pyrophyllite, dickite, topaz, pyrite, and a range of silica minerals. Farther outward from the advanced argillic alteration are broader zones of propylitic (chlorite-calcite-illite-pyrite) and smectite-pyrite alteration. Initial S-O isotopic data indicate that alunite formed by high-temperature disproportionation of magmatic SO2. The ~3 km2 MD <span class="hlt">system</span>, centered about 1 km SE of Mt. Diller, extends 3 km ESE to near Bumpass Hell. Lavas and breccias of the Mill Canyon sequence and the Mt. Diller sequence (ca. 400 ka) have been <span class="hlt">hydrothermally</span> altered. Although the center of the MD <span class="hlt">system</span> is largely obscured by landslides and by superimposed steam-heated acid leaching related to present-day <span class="hlt">hydrothermal</span> activity, recognized core alteration consists of pyrite-rich quartz-dickite and quartz-kaolinite breccias; pyrite content locally exceeds 50%. Only minor amounts of alunite and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatCo...610150H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatCo...610150H"><span>Talc-dominated seafloor deposits reveal a new class of <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hodgkinson, Matthew R. S.; Webber, Alexander P.; Roberts, Stephen; Mills, Rachel A.; Connelly, Douglas P.; Murton, Bramley J.</p> <p>2015-12-01</p> <p>The Von Damm Vent Field (VDVF) is located on the flanks of the Mid-Cayman Spreading Centre, 13 km west of the axial rift, within a gabbro and peridotite basement. Unlike any other active vent field, <span class="hlt">hydrothermal</span> precipitates at the VDVF comprise 85-90% by volume of the magnesium silicate mineral, talc. <span class="hlt">Hydrothermal</span> fluids vent from a 3-m high, 1-m diameter chimney and other orifices at up to 215 °C with low metal concentrations, intermediate pH (5.8) and high concentrations (667 mmol kg-1) of chloride relative to seawater. Here we show that the VDVF vent fluid is generated by interaction of seawater with a mafic and ultramafic basement which precipitates talc on mixing with seawater. The heat flux at the VDVF is measured at 487+/-101 MW, comparable to the most powerful magma-driven <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> known, and may represent a significant mode of off-axis oceanic crustal cooling not previously recognized or accounted for in global models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032253','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032253"><span>Identifying bubble collapse in a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> using hidden Markov models</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dawson, P.B.; Benitez, M.C.; Lowenstern, J. B.; Chouet, B.A.</p> <p>2012-01-01</p> <p>Beginning in July 2003 and lasting through September 2003, the Norris Geyser Basin in Yellowstone National Park exhibited an unusual increase in ground temperature and <span class="hlt">hydrothermal</span> activity. Using hidden Markov model theory, we identify over five million high-frequency (>15Hz) seismic events observed at a temporary seismic station deployed in the basin in response to the increase in <span class="hlt">hydrothermal</span> activity. The source of these seismic events is constrained to within ???100 m of the station, and produced ???3500-5500 events per hour with mean durations of ???0.35-0.45s. The seismic event rate, air temperature, hydrologic temperatures, and surficial water flow of the geyser basin exhibited a marked diurnal pattern that was closely associated with solar thermal radiance. We interpret the source of the seismicity to be due to the collapse of small steam bubbles in the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, with the rate of collapse being controlled by surficial temperatures and daytime evaporation rates. copyright 2012 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4703833','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4703833"><span>Talc-dominated seafloor deposits reveal a new class of <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hodgkinson, Matthew R. S.; Webber, Alexander P.; Roberts, Stephen; Mills, Rachel A.; Connelly, Douglas P.; Murton, Bramley J.</p> <p>2015-01-01</p> <p>The Von Damm Vent Field (VDVF) is located on the flanks of the Mid-Cayman Spreading Centre, 13 km west of the axial rift, within a gabbro and peridotite basement. Unlike any other active vent field, <span class="hlt">hydrothermal</span> precipitates at the VDVF comprise 85–90% by volume of the magnesium silicate mineral, talc. <span class="hlt">Hydrothermal</span> fluids vent from a 3-m high, 1-m diameter chimney and other orifices at up to 215 °C with low metal concentrations, intermediate pH (5.8) and high concentrations (667 mmol kg−1) of chloride relative to seawater. Here we show that the VDVF vent fluid is generated by interaction of seawater with a mafic and ultramafic basement which precipitates talc on mixing with seawater. The heat flux at the VDVF is measured at 487±101 MW, comparable to the most powerful magma-driven <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> known, and may represent a significant mode of off-axis oceanic crustal cooling not previously recognized or accounted for in global models. PMID:26694142</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26694142','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26694142"><span>Talc-dominated seafloor deposits reveal a new class of <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hodgkinson, Matthew R S; Webber, Alexander P; Roberts, Stephen; Mills, Rachel A; Connelly, Douglas P; Murton, Bramley J</p> <p>2015-12-22</p> <p>The Von Damm Vent Field (VDVF) is located on the flanks of the Mid-Cayman Spreading Centre, 13 km west of the axial rift, within a gabbro and peridotite basement. Unlike any other active vent field, <span class="hlt">hydrothermal</span> precipitates at the VDVF comprise 85-90% by volume of the magnesium silicate mineral, talc. <span class="hlt">Hydrothermal</span> fluids vent from a 3-m high, 1-m diameter chimney and other orifices at up to 215 °C with low metal concentrations, intermediate pH (5.8) and high concentrations (667 mmol kg(-1)) of chloride relative to seawater. Here we show that the VDVF vent fluid is generated by interaction of seawater with a mafic and ultramafic basement which precipitates talc on mixing with seawater. The heat flux at the VDVF is measured at 487±101 MW, comparable to the most powerful magma-driven <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> known, and may represent a significant mode of off-axis oceanic crustal cooling not previously recognized or accounted for in global models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003TrGeo...6..181G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003TrGeo...6..181G"><span><span class="hlt">Hydrothermal</span> Processes</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.; von Damm, K. L.</p> <p>2003-12-01</p> <p>What is <span class="hlt">Hydrothermal</span> Circulation?<span class="hlt">Hydrothermal</span> circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) <span class="hlt">system</span>. 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 <span class="hlt">hydrothermal</span> circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930034010&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dorganic%2Bsynthesis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930034010&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dorganic%2Bsynthesis"><span><span class="hlt">Hydrothermal</span> organic synthesis experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, Everett L.</p> <p>1992-01-01</p> <p>Ways in which heat is useful in organic synthesis experiments are described, and experiments on the <span class="hlt">hydrothermal</span> destruction and synthesis of organic compounds are discussed. It is pointed out that, if heat can overcome kinetic barriers to the formation of metastable states from reduced or oxidized starting materials, abiotic synthesis under <span class="hlt">hydrothermal</span> conditions is a distinct possibility. However, carefully controlled experiments which replicate the descriptive variables of natural <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> have not yet been conducted with the aim of testing the hypothesis of <span class="hlt">hydrothermal</span> organic <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H32F..01W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H32F..01W"><span>The Interplay Between Saline Fluid Flow and Dynamic Permeability in Magmatic-<span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weis, P.</p> <p>2014-12-01</p> <p>Magmatic-<span class="hlt">hydrothermal</span> ore deposits document the interplay between saline fluid flow and rock permeability. Numerical simulations of multi-phase flow of variably miscible, compressible H20-NaCl fluids in concert with a dynamic permeability model can reproduce characteristics of porphyry copper and epithermal gold <span class="hlt">systems</span>. This dynamic permeability model incorporates depth-dependent permeability profiles characteristic for tectonically active crust as well as pressure- and temperature-dependent relationships describing hydraulic fracturing and the transition from brittle to ductile rock behavior. In response to focused expulsion of magmatic fluids from a crystallizing upper crustal magma chamber, the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> self-organizes into a hydrological divide, separating an inner part dominated by ascending magmatic fluids under near-lithostatic pressures from a surrounding outer part dominated by convection of colder meteoric fluids under near-hydrostatic pressures. This hydrological divide also provides a mechanism to transport magmatic salt through the crust, and prevents the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> to become "clogged" by precipitation of solid halite due to depressurization of saline, high-temperature magmatic fluids. The same physical processes at similar permeability ranges, crustal depths and flow rates are relevant for a number of active <span class="hlt">systems</span>, including geothermal resources and excess degassing at volcanos. The simulations further suggest that the described mechanism can separate the base of free convection in high-enthalpy geothermal <span class="hlt">systems</span> from the magma chamber as a driving heat source by several kilometers in the vertical direction in tectonic settings with hydrous magmatism. This hydrology would be in contrast to settings with anhydrous magmatism, where the base of the geothermal <span class="hlt">systems</span> may be closer to the magma chamber.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT........18G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT........18G"><span>From Magma Formation to <span class="hlt">Hydrothermal</span> Alteration: an Integrated Study of the Martian Crust Using Thermodynamic Modeling of Geochemical <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Griffith, Laura Lee</p> <p></p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> have undoubtedly occurred on Mars. These <span class="hlt">systems</span> are of interest for a number of reasons. <span class="hlt">Hydrothermal</span> alteration of host rocks can have effects on the atmosphere of the planet, the volatile budget, local hydrologic patterns, the rheology of the rocks, their ability to resist weathering, and even lower the melting temperature of crustal rocks. In addition, there is a connection between <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and the origin of life on earth that raises questions about life on Mars. The approach taken used theoretical geochemical modeling techniques to model hypothetical <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on Mars. The initial phase of the research involved understanding terrestrial <span class="hlt">systems</span> that were used as analogs for Martian <span class="hlt">systems</span>. Compositions of Icelandic host rocks were used as input for extensive modeling calculations. These calculations investigated the roles of initial rock composition, fluid temperature, partial pressure of carbon dioxide in the fluid, water to rock ratio, and oxygen fugacity of the fluid on alteration assemblages. The second phase utilized the data available on the SNC meteorites (they are suspected to come from Mars) as the basis for <span class="hlt">hydrothermal</span> <span class="hlt">system</span> modeling. The focus of this investigation was the variability of alteration assemblages that could be produced from the SNC meteorites. The final investigation broadened the scope of possible substrates for <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> by using theoretical geochemical modeling of igneous processes to produce likely Martial crustal rock compositions from a possible Martial mantle composition. A variety of variables (depth of initial melting, amount of initial melt, cooling rate during ascent, and depth of final emplacement) were examined to determine their effects on compositions of the calculated melts. Several rock compositions produced by the igneous modeling were used as input for <span class="hlt">hydrothermal</span> modeling calculations. These calculations examined possible differences in alteration</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>Application of AUVs in the Exploration for and Characterization of Arc Volcano Seafloor <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></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> <span class="hlt">systems</span> associated with arc volcanoes has provided important information at a scale relevant to the study of these <span class="hlt">systems</span>. 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 site 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 site. 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://pubs.er.usgs.gov/publication/70018270','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018270"><span>Emerald mineralization and metasomatism of amphibolite, khaltaro granitic pegmatite - <span class="hlt">Hydrothermal</span> vein <span class="hlt">system</span>, Haramosh Mountains, Northern Pakistan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Laurs, B.M.; Dilles, J.H.; Snee, L.W.</p> <p>1996-01-01</p> <p> single fluid of magmatic origin with ??18OH2O = 8??? produced the pegmatite-vein <span class="hlt">system</span> and <span class="hlt">hydrothermal</span> alteration at temperatures between 550 and 400??C. The formation of emerald results from introduction of HF-rich magmatic-<span class="hlt">hydrothermal</span> fluids into the amphibolite, which caused hydrogen ion metasomatism and released Cr and Fe into the pegmatite-vein <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V21A3024K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V21A3024K"><span>Porosity estimates of the upper crust in the <span class="hlt">Endeavour</span> segment of the 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>Kim, E.; Toomey, D. R.; Hooft, E. E. E.; Wilcock, W. S. D.; Weekly, R. T.; Lee, S. M.; Kim, Y.</p> <p>2015-12-01</p> <p>We estimate upper crustal porosity variations using the differential effective medium (DEM) theory to interpret the observed seismic velocity variations for the <span class="hlt">Endeavour</span> segment of the Juan de Fuca Ridge, an intermediate spreading center [Weekly et al., 2014]. We use six P-wave vertical velocity profiles averaged within 5 km × 10 km areas to estimate the porosity at depths from 0.4 km to 2 km. The profile regions cover on-axis, east and west flanks of the central <span class="hlt">Endeavour</span> segment and three regions of the segment ends including the <span class="hlt">Endeavour</span>-West Valley (E-WV) and the Cobb overlapping spreading centers (OSCs) and the relict Middle Valley. At the segment center, our calculated porosities on-axis and on the east and west flanks agree well with the apparent bulk porosities measured in Hole 504B at intermediate-spreading Costa Rica Rift [Becker, 1990] and decrease from 5-15% to 2-7% from 0.5 km to 1 km depth and seal by 2 km depth. At all depths, our calculated porosities on the east and west flanks are lower than those on-axis by ~1.3-3%. This indicates the infilling of cracks by mineral precipitation associated with near-axis <span class="hlt">hydrothermal</span> circulation [Newman et al., 2011]. At the segment ends, upper crustal velocities are lower than those in the segment center at depths < 2 km. These lower velocities are attributed to higher porosities (10-20% at 0.4 km decreasing to 3-6% at 2 km depth). This may indicate that fracturing in the OSCs strongly affects porosity at shallow depths. Between 0.7 km and 1 km, porosities estimated in all regions using pore aspect ratios of 0.05, 0.1 and 0.2 are higher than those from Hole 504B indicating that the aspect ratio of cracks may be smaller than 0.05. There also appears to be a spreading rate dependence to upper crustal porosity structure. On-axis at the <span class="hlt">Endeavour</span> segment, the calculated porosities from 0.4 km to 2 km are higher than those at the Lucky Strike segment, a slow spreading center [Seher et al., 2010]. Specifically at 2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17.3835A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17.3835A"><span>Lithium isotopic systematics of submarine vent fluids from arc and back-arc <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the 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>Araoka, Daisuke; Nishio, Yoshiro; Gamo, Toshitaka; Yamaoka, Kyoko; Kawahata, Hodaka</p> <p>2016-10-01</p> <p>The Li concentration and isotopic composition (δ7Li) in submarine vent fluids are important for oceanic Li budget and potentially useful for investigating <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> deep under the seafloor because <span class="hlt">hydrothermal</span> vent fluids are highly enriched in Li relative to seawater. Although Li isotopic geochemistry has been studied at mid-ocean-ridge (MOR) <span class="hlt">hydrothermal</span> sites, in arc and back-arc settings Li isotopic composition has not been systematically investigated. Here we determined the δ7Li and 87Sr/86Sr values of 11 end-member fluids from 5 arc and back-arc <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the western Pacific and examined Li behavior during high-temperature water-rock interactions in different geological settings. In sediment-starved <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> (Manus Basin, Izu-Bonin Arc, Mariana Trough, and North Fiji Basin), the Li concentrations (0.23-1.30 mmol/kg) and δ7Li values (+4.3‰ to +7.2‰) of the end-member fluids are explained mainly by dissolution-precipitation model during high-temperature seawater-rock interactions at steady state. Low Li concentrations are attributable to temperature-related apportioning of Li in rock into the fluid phase and phase separation process. Small variation in Li among MOR sites is probably caused by low-temperature alteration process by diffusive <span class="hlt">hydrothermal</span> fluids under the seafloor. In contrast, the highest Li concentrations (3.40-5.98 mmol/kg) and lowest δ7Li values (+1.6‰ to +2.4‰) of end-member fluids from the Okinawa Trough demonstrate that the Li is predominantly derived from marine sediments. The variation of Li in sediment-hosted sites can be explained by the differences in degree of <span class="hlt">hydrothermal</span> fluid-sediment interactions associated with the thickness of the marine sediment overlying these <span class="hlt">hydrothermal</span> sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5569857','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5569857"><span>Geophysical characteristics of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of Kilauea volcano, Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kauahikaua, J. )</p> <p>1993-08-01</p> <p>Clues to the structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data allow separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper east rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'e fault <span class="hlt">system</span>. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Heat flows of 370--820 mW/m[sup 2] are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. 115 refs., 13 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V11A3057S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V11A3057S"><span>Numerical Modeling of Brine Formation and Serpentinization at the Rainbow <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sekhar, P.; Lowell, R. P.</p> <p>2015-12-01</p> <p>The Rainbow <span class="hlt">hydrothermal</span> field on the Mid Atlantic Ridge is a high-temperature <span class="hlt">hydrothermal</span> <span class="hlt">system</span> hosted in peridotite. The vent fluids are rich in methane and hydrogen suggesting that serpentinization is occurring at depth in the <span class="hlt">system</span>. Vent temperature of ~365°C, salinity of ~4.5 wt%, and heat output of ~500 MW suggest that Rainbow field is driven by a magmatic heat source and that phase separation is occurring at depth. To understand the origin of high salinity in the Rainbow <span class="hlt">hydrothermal</span> fluid, we construct a 2D numerical model of two-phase <span class="hlt">hydrothermal</span> circulation using the numerical simulator FISHES. This code uses the finite volume method to solve the conservation of mass, momentum, energy, and salt equations in a NaCl-H2O fluid. We simulate convection in an open top 2D box at a surface pressure of 23 MPa and seawater temperature of 10oC. The bottom and sides of the box are insulated and impermeable, and a fixed temperature distribution is maintained at the base to ensure phase separation. We first consider a homogeneous model with a permeability of 10-13 m2 and <span class="hlt">system</span> depths of 2 and 1 km, respectively. The brine-derived fluid from the deeper <span class="hlt">system</span> barely exceeds seawater, whereas the shallower <span class="hlt">system</span> produces a short pulse of 9.0 wt% for 5 years. We then consider 1 km deep <span class="hlt">systems</span> with a high permeability discharge zone of 5x10-13 m2 that corresponds to a fault zone, surrounded by recharge zones of 10-13, 10-14 and 10-15 m2, respectively. The model with recharge permeability of 10-14 m2 yields stable plumes that vent brine-derived fluid of 4.2 wt% for 150 years. Using the quasi- steady state of this model as a base, we estimate the rate of serpentinization along the fluid flow paths, and evolution of porosity and permeability. This analysis will indicate the extent to which serpentinization will affect the dynamics of the <span class="hlt">system</span> and will provide insight into methane flux in the Rainbow vent field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9613W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9613W"><span>Laboratory experiments and continuous fluid monitoring at Campi Flegrei to understand pressure transients in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woith, Heiko; Mangiacapra, Annarita; Chiodini, Giovanni; Pilz, Marco; Walter, Thomas</p> <p>2015-04-01</p> <p>The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> beneath Campi Flegrei is strongly affected by sub-surface processes as manifested by the existence of a geothermal "plume" below Solfatara (Bruno et al. 2007), associated with formation of new fumaroles and the spatial pattern of exhalation vents. Within the frame of MED-SUV (The MED-SUV project has received funding from the European Union Seventh Framework Programme (FP7) under Grant agreement no 308665), pressure tansients in the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Campi Flegrei shall be studied using a combination of laboratory experiments and continuous pressure/temperature monitoring at fumaroles, mudpools, hot springs, and geothermal wells. Four groundwater monitoring sites were installed in September 2013: one in the Fangaia mud pool inside Solfatara and three within the geothermal area of Agnano, which is located roughly 3 km to the East of the Solfatara crater. In 2014 additional sensors were installed in Pisciarelli. Autonomous devices are being used to record the water level and water temperature at 10 minute intervals. Records reveal significant changes of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in September 2013 at the Agnano main spring during the night from 23 to 24 September. Both, the water level and the water temperature dropped significantly, confirmed by visual inspection of the spa operators. The pool of the main spring almost emptied and the flow rate was significantly reduced, implying a profound change in the <span class="hlt">system</span>. Similar water level drops occurred in the following months. Gas bubbles are likely to play a major role with respect to spatio-temporal variations in shallow fluid <span class="hlt">systems</span> below Solfatara. Thus, additional to the field measurements we investigate potential bubble-related mechanisms capable to increase fluid pressure. The BubbleLab at GFZ has been setup. We are able to simulate earthquake ground motions with a shaking table, track the size and velocity of rising bubbles via a camera <span class="hlt">system</span>, and quantify transients with a set of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26394465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26394465"><span>[Chemical Potentials of <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> and Formation of Coupled Modular Metabolic Pathways].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marakushev, S A; Belonogova, O V</p> <p>2015-01-01</p> <p>According to Gibbs J.W. the number of independent components is the least number of those chemical constituents, by combining which the compositions of all possible phases in the <span class="hlt">system</span> can be obtained, and at the first stages of development of the primary metabolism of the three-component <span class="hlt">system</span> C-H-O different hydrocarbons and molecular hydrogen were used as an energy source for, it. In the Archean <span class="hlt">hydrothermal</span> conditions under the action of the phosphorus chemical potential the C-H-O <span class="hlt">system</span> was transformed into a four-component <span class="hlt">system</span> C-H-O-P setting up a gluconeogenic <span class="hlt">system</span>, which became the basis of power supply for a protometabolism, and formation of a new cycle of CO2 fixation (reductive pentose phosphate pathway). It is shown that parageneses (association) of certain substances permitted the modular constructions of the central metabolism of the <span class="hlt">system</span> C-H-O-P and the formed modules appear in association with each other in certain physicochemical <span class="hlt">hydrothermal</span> conditions. Malate, oxaloacetate, pyruvate and phosphoenolpyruvate exhibit a turnstile-like mechanism of switching reaction directions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1807&hterms=history+space+rockets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhistory%2Bspace%2Brockets','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1807&hterms=history+space+rockets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhistory%2Bspace%2Brockets"><span>Liftoff of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-97</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>Space Shuttle <span class="hlt">Endeavour</span> rockets off Launch Pad 39B in a perfect, on-time launch. Liftoff of <span class="hlt">Endeavour</span> occurred at 10:06:01 p.m. EST on mission STS-97. <span class="hlt">Endeavour</span> and its five-member crew will deliver U.S. solar arrays to the International Space Station and be the first Shuttle crew to visit the Station'''s first resident crew. The 11-day mission includes three spacewalks. This marks the 101st mission in Space Shuttle history and the 25th night launch. <span class="hlt">Endeavour</span> is expected to land Dec. 11 at 6:19 p.m. EST.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18163870','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18163870"><span>Temporal changes in fluid chemistry and energy profiles in the vulcano island <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rogers, Karyn L; Amend, Jan P; Gurrieri, Sergio</p> <p>2007-12-01</p> <p>In June 2003, the geochemical composition of geothermal fluids was determined at 9 sites in the Vulcano <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, including sediment seeps, geothermal wells, and submarine vents. Compositional data were combined with standard state reaction properties to determine the overall Gibbs free energy (DeltaG(r) ) for 120 potential lithotrophic and heterotrophic reactions. Lithotrophic reactions in the H-O-N-S-C-Fe <span class="hlt">system</span> were considered, and exergonic reactions yielded up to 120 kJ per mole of electrons transferred. The potential for heterotrophy was characterized by energy yields from the complete oxidation of 6 carboxylic acids- formic, acetic, propanoic, lactic, pyruvic, and succinic-with the following redox pairs: O(2)/H(2)O, SO(4) (2)/H(2)S, NO(3) ()/NH(4) (+), S(0)/H(2)S, and Fe(3)O(4)/Fe(2+). Heterotrophic reactions yielded 6-111 kJ/mol e(). Energy yields from both lithotrophic and heterotrophic reactions were highly dependent on the terminal electron acceptor (TEA); reactions with O(2) yielded the most energy, followed by those with NO(3) (), Fe(III), SO(4) (2), and S(0). When only reactions with complete TEA reduction were included, the exergonic lithotrophic reactions followed a similar electron tower. Spatial variability in DeltaG(r) was significant for iron redox reactions, owing largely to the wide range in Fe(2+) and H(+) concentrations. Energy yields were compared to those obtained for samples collected in June 2001. The temporal variations in geochemical composition and energy yields observed in the Vulcano <span class="hlt">hydrothermal</span> <span class="hlt">system</span> between 2001 and 2003 were moderate. The largest differences in DeltaG(r) over the 2 years were from iron redox reactions, due to temporal changes in the Fe(2+) and H(+) concentrations. The observed variations in fluid composition across the Vulcano <span class="hlt">hydrothermal</span> <span class="hlt">system</span> have the potential to influence not only microbial diversity but also the metabolic strategies of the resident microbial communities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017161','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017161"><span>Mass transfer constraints on the chemical evolution of an active <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, Valles caldera, New Mexico</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>White, A.F.; Chuma, N.J.; Goff, F.</p> <p>1992-01-01</p> <p>Partial equilibrium conditions occur between fluids and secondary minerals in the Valles <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, contained principally in the Tertiary rhyolitic Bandelier Tuff. The mass transfer processes are governed by reactive phase compositions, surface areas, water-rock ratios, reaction rates, and fluid residence times. Experimental dissolution of the vitric phase of the tuff was congruent with respect to Cl in the solid and produced reaction rates which obeyed a general Arrhenius release rate between 250 and 300??C. The 18O differences between reacted and unreacted rock and fluids, and mass balances calculations involving Cl in the glass phase, produced comparable water-rock ratios of unity, confirming the importance of irreversible reaction of the vitric tuff. A fluid residence time of approximately 2 ?? 103 years, determined from fluid reservoir volume and discharge rates, is less than 0.2% of the total age of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> and denotes a geochemically and isotopically open <span class="hlt">system</span>. Mass transfer calculations generally replicated observed reservoir pH, Pco2, and PO2 conditions, cation concentrations, and the secondary mineral assemblage between 250 and 300??C. The only extraneous component required to maintain observed calcite saturation and high Pco2 pressures was carbon presumably derived from underlying Paleozoic limestones. Phase rule constraints indicate that Cl was the only incompatible aqueous component not controlled by mineral equilibrium. Concentrations of Cl in the reservoir directly reflect mass transport rates as evidenced by correlations between anomalously high Cl concentrations in the fluids and tuff in the Valles caldera relative to other <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in rhyolitic rocks. ?? 1992.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGP31B..01P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGP31B..01P"><span>Imaging the magmatic and <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of Long Valley Caldera, California with magnetotellurics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peacock, J.; Mangan, M.; McPhee, D.; Ponce, D. A.</p> <p>2015-12-01</p> <p>Long Valley Caldera (LVC) in Eastern California contains active <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, areas of episodic seismicity, and areas of elevated gas emissions, all of which are related to a deeper magmatic <span class="hlt">system</span> that is not well characterized. To better image the Long Valley magmatic <span class="hlt">system</span>, 60 full-tensor broadband magnetotelluric (MT) stations were collected in LVC and modeled in three-dimensions to constrain the subsurface electrical resistivity structure down to 30 km. Three conductive zones are imaged in the preferred resistivity model. The most prominent conductive zone (<7 Ohm-m) is located 5 km beneath the resurgent dome (near the center of Long Valley Caldera), where it elongates in a north-south direction, and has westward connection to the surface close to well 44-16 near Deer Mountan. This conductive zone is interpreted to be an accumulation zone of <span class="hlt">hydrothermal</span> fluids originating from a deeper magmatic source. The shape of the conductive body suggests that the fluids pool under the resurgent dome and migrate westward, upwelling just south of well 44-16 to feed the near surface geothermal <span class="hlt">system</span>. A second conductive zone (<10 Ohm-m) is 4 km southeast of the resurgent dome and 5 km deep and coincident with the seismic swarm of 2014. This is another zone of fluid accumulation, where the source could be the fluid accumulation zone to the west or an independent deeper source. The third conductive anomaly (<10 Ohm-m) is a few kilometers south of the resurgent dome below a depth of 15 km, and collocated with a low p- and s-wave velocity zone, and directly beneath a GPS inflation area, all of which advocate for a magma mush zone of as much as 30% interstitial melt. The preferred resistivity model suggests an accumulation of <span class="hlt">hydrothermal</span> fluids 5 km below the resurgent dome that originates from a deeper magmatic source at 15 km depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V52A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V52A..01C"><span>Source Dynamics of Long-Period Seismicity in Volcanic and <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chouet, B. A.</p> <p>2006-12-01</p> <p>Long-period (LP) seismicity, including individual LP events and tremor, is widely observed in relation to magmatic and <span class="hlt">hydrothermal</span> activities in volcanic areas and is recognized as a precursory phenomenon for eruptive activity. The waveform of the LP event is characterized by simple decaying harmonic oscillations except for a brief interval at the event onset. This characteristic event signature is commonly interpreted as oscillations of a fluid-filled resonator in response to a time-localized excitation. By the same token, tremor may be viewed as oscillations of the same resonator in response to a sustained excitation. Because the properties of the resonator <span class="hlt">system</span> at the source of the LP event can be inferred from the complex frequencies of the decaying harmonic oscillations in the tail of the seismogram, these events are particularly important in the quantification of volcanic and <span class="hlt">hydrothermal</span> processes. The damped oscillations in the LP coda are characterized by two parameters, T and Q, where T is the period of the dominant mode of oscillation, and Q is the quality factor of the oscillatory <span class="hlt">system</span> representing the combined effects of radiation and intrinsic losses. Typical periods observed for LP events are in the range 0.2 - 2 s, while observed Q range from values near 1 to values larger than 100. Waveform inversions of LP signals carried out so far point to a crack geometry at the source of these events. Detailed investigations of the oscillating characteristics of LP sources based on the fluid-filled crack model suggest source dimensions ranging from tens to several hundred meters. Such studies further indicate that dusty gases and bubbly basalt are the most common types of fluids involved at the source of LP events in magmatic <span class="hlt">systems</span>, while misty gases, steam and bubbly water commonly represent LP events of <span class="hlt">hydrothermal</span> origin. Observations carried out in different volcanic settings point to a wide variety of LP excitation mechanisms. At Stromboli</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B11D0717H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B11D0717H"><span>Geophysical Characterization of the Borax Lake <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> in the Alvord Desert, Southeastern Oregon.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hess, S.; Paul, C.; Bradford, J.; Lyle, M.; Clement, W.; Liberty, L.; Myers, R.; Donaldson, P.</p> <p>2003-12-01</p> <p>We are conducting a detailed geophysical characterization of an active <span class="hlt">hydrothermal</span> <span class="hlt">system</span> as part of an interdisciplinary project aiming to study the link between the physical characteristics of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and biota that occupy those <span class="hlt">systems</span>. The Borax Lake <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> (BLHS), consisting of Borax Lake and the surrounding hot springs, is located near the center of the Alvord Basin in southeastern Oregon. As a result of Basin and Range extension, the Alvord Basin is a north-south trending graben bounded by the Steens Mountains to the west and the Trout Creek Mountains to the east. We are using several geophysical techniques to generate both basin-wide and high-resolution local characterizations of the Alvord Basin and the BLHS. To date we have completed two scales of seismic reflection surveys: an east-west trending basin scale survey and a shallow (~10 - 300 m depth) 3D survey of the BLHS. The basin scale seismic survey consists of 11 km of 2D, 60 fold CMP data acquired with a 200 lb accelerated weight drop. We acquired the 3D survey of the BLHS using a 7.62x39 mm SKS rifle and 240 channel recording <span class="hlt">system</span>. The 3D patch covers ~ 90,000 sq. m with a maximum inline offset aperture of 225 m, crossline aperture of 75 m, and 360 degree azimuthal coverage. Additionally, we have completed a regional total-field magnetic survey for a large portion of the Alvord Basin and a 3D transient electromagnetic (TEM) survey of the BLHS. The 3D TEM survey covers the central portion of the 3D seismic survey. Initial results from the regional magnetic and seismic surveys indicate a mid-basin basement high. The basement high appears to correlate with the northeast trending BLHS. Additionally, the cross-basin seismic profile clearly shows that recent deformation has primarily been along an eastward dipping normal fault that bounds the basement high to the east. This suggests that both spatial and temporal characteristics of deformation control <span class="hlt">hydrothermal</span> activity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8179M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8179M"><span>Multifractal spatial organisation in <span class="hlt">hydrothermal</span> gold <span class="hlt">systems</span> of the Archaean Yilgarn craton, Western Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Munro, Mark; Ord, Alison; Hobbs, Bruce</p> <p>2015-04-01</p> <p>A range of factors controls the location of <span class="hlt">hydrothermal</span> alteration and gold mineralisation in the Earth's crust. These include the broad-scale lithospheric architecture, availability of fluid sources, fluid composition and pH, pressure-temperature conditions, microscopic to macroscopic structural development, the distribution of primary lithologies, and the extent of fluid-rock interactions. Consequently, the spatial distribution of alteration and mineralization in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is complex and often considered highly irregular. However, despite this, do they organize themselves in a configuration that can be documented and quantified? Wavelets, mathematical functions representing wave-like oscillations, are commonly used in digital signals analysis. Wavelet-based multifractal analysis involves incrementally scanning a wavelet across the dataset multiple times (varying its scale) and recording its degree of fit to the signal at each interval. This approach (the wavelet transform modulus maxima method) highlights patterns of self-similarity present in the dataset and addresses the range of scales over which these patterns replicate themselves (expressed by their range in 'fractal dimension'). Focusing on seven gold ore bodies in the Archaean Yilgarn craton of Western Australia, this study investigates whether different aspects of <span class="hlt">hydrothermal</span> gold <span class="hlt">systems</span> evolve to organize themselves spatially as multifractals. Four ore bodies were selected from the Sunrise Dam deposit (situated in the Laverton tectonic zone of the Kurnalpi terrane) in addition to the Imperial, Majestic and Salt Creek gold prospects, situated in the Yindarlgooda dome of the Mount Monger goldfield (approximately 40km due east of Kalgoorlie). The Vogue, GQ, Cosmo East and Astro ore bodies at Sunrise Dam were chosen because they exhibit different structural geometries and relationships between gold and associated host-rock alteration styles. Wavelet-based analysis was conducted on 0.5m and 1m</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1912.2083J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1912.2083J"><span>Organic Biomarker Preservation in Silica-Rich <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> with Implications to Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jahnke, L. L.; Parenteau, M. N.; Farmer, J. D.</p> <p>2016-05-01</p> <p>Microbial community structure and preservation of organic matter in siliceous <span class="hlt">hydrothermal</span> environments is a critical issue given the discovery of <span class="hlt">hydrothermal</span> vents and silica on Mars. Here we discuss preservation of cyanobacterial biomarker lipid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.V72A1305G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V72A1305G"><span>Dual-scale <span class="hlt">hydrothermal</span> circulation inferred from detailed heat flow measurements in the Suiyo Seamount <span class="hlt">Hydrothermal</span> <span class="hlt">System</span>, Izu-Bonin Arc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gomado, M.; Kinoshita, M.</p> <p>2002-12-01</p> <p><span class="hlt">Hydrothermal</span> activity within the caldera of Suiyo Seamount was investigated in detail using manned or remotely-operated submersibles, and by deep-tow imagery and seismic surveys. <span class="hlt">Hydrothermal</span> regime in the Suiyo-seamount is characterized by a geochemically uniform fluid, shallow reservoir depth, very permeable seafloor, and venting without creating big chimneys. Detailed heat flow surveys were carried out through four research cruises conducted in 2001-2002. Geothermal probes, called SAHF (Stand-Alone Heat Flow) meter, are 1m in length, and five thermistors are installed at 11-12 cm intervals. Heat flow is highest (> 10 W/m2) within the active area. These values were obtained close to black smokers, thus are affected by the venting or very shallow reservoirs. To the east, heat flow is uniform around 4 W/m2. Since there were no indications of discharge, this area is dominated by thermal conduction, and its heat source would be a <span class="hlt">hydrothermal</span> reservoir capped by some impermeable layer. To the west, we detected very low heat flow values of less than 0.3 W/m2, only several tens of meters away from the active area. A similar heat flow anomaly was detected in the TAG hyudrothermal mound of the Mid-Atlantic Ridge (Becker et al., 1996). We penetrated at 1-2 m away from two isolated active sulfide mounds. At both sites subbottom temperatures were about 40 degC at 10-20 cm depth, then they decreased to about 20 degC at 30-40cm. The temperature reversals suggest a meter-scale <span class="hlt">hydrothermal</span> circulation, where a hot fluid discharges as a branch flow from the main vent to the mound. An impermeable structure of the mound and a permeable sediment surrounding the mound would make this very local circulation possible. We suggest a dual scale <span class="hlt">hydrothermal</span> circulation <span class="hlt">system</span>, one with several meters scale, and the other with few tens of meters scale. The former would be driven by a suction created by discrete venting of high temperature fluid, and the latter is a regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JVGR...56..401K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JVGR...56..401K"><span>Relations of ammonium minerals at several <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the western U.S.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krohn, M. Dennis; Kendall, Carol; Evans, John R.; Fries, Terry L.</p> <p>1993-08-01</p> <p>Ammonium bound to silicate and sulfate minerals has recently been located at several major <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the western U.S. utilizing newly-discovered near-infrared spectral properties. Knowledge of the origin and mineralogic relations of ammonium minerals at known <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is critical for the proper interpretation of remote sensing data and for testing of possible links to mineralization. Submicroscopic analysis of ammonium minerals from two mercury- and gold-bearing hot-springs deposits at Ivanhoe, Nevada and McLaughlin, California shows that the ammonium feldspar, buddingtonite, occurs as fine-grained euhedral crystals coating larger sulfide and quartz crystals. Ammonium feldspar seems to precipitate relatively late in the crystallization sequence and shows evidence for replacement of NH 4 + by K + or other monovalent cations. Some buddingtonite is observed in close association with mercury, but not with gold. Ammonioalunite is found in a variety of isolated crystal forms at both deposits. Nitrogen isotopic values for ammonium-bearing minerals show a 14‰ range in composition, precluding assignment of a specific provenance to the nitrogen. The correlations of nitrogen isotopic values with depth and ammonium content suggest some loss of nitrogen in the oxidizing supergene environment, possibly as a metastable mineral. The high ammonium content in these <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, the close association to mercury, and the small crystal size of the ammonium-bearing minerals all suggest that ammonium may be transported in a late-stage vapor phase or as an organic volatile. Such a process could lead to the formation of a non-carbonaceous organic aureole above a buried geothermal source. The discovery of a 10-km outcrop of ammonium minerals confirms that significant substitution of ammonium in minerals is possible over an extensive area and that remote sensing is a feasible means to detect such aureoles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017337','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017337"><span>Relations of ammonium minerals at several <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the western U.S.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Krohn, M.D.; Kendall, C.; Evans, J.R.; Fries, T.L.</p> <p>1993-01-01</p> <p>Ammonium bound to silicate and sulfate minerals has recently been located at several major <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the western U.S. utilizing newly-discovered near-infrared spectral properties. Knowledge of the origin and mineralogic relations of ammonium minerals at known <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is critical for the proper interpretation of remote sensing data and for testing of possible links to mineralization. Submicroscopic analysis of ammonium minerals from two mercury- and gold-bearing hot-springs deposits at Ivanhoe, Nevada and McLaughlin, California shows that the ammonium feldspar, buddingtonite, occurs as fine-grained euhedral crystals coating larger sulfide and quartz crystals. Ammonium feldspar seems to precipitate relatively late in the crystallization sequence and shows evidence for replacement of NH4+ by K+ or other monovalent cations. Some buddingtonite is observed in close association with mercury, but not with gold. Ammonioalunite is found in a variety of isolated crystal forms at both deposits. Nitrogen isotopic values for ammonium-bearing minerals show a 14??? range in composition, precluding assignment of a specific provenance to the nitrogen. The correlations of nitrogen isotopic values with depth and ammonium content suggest some loss of nitrogen in the oxidizing supergene environment, possibly as a metastable mineral. The high ammonium content in these <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, the close association to mercury, and the small crystal size of the ammonium-bearing minerals all suggest that ammonium may be transported in a late-stage vapor phase or as an organic volatile. Such a process could lead to the formation of a non-carbonaceous organic aureole above a buried geothermal source. The discovery of a 10-km outcrop of ammonium minerals confirms that significant substitution of ammonium in minerals is possible over an extensive area and that remote sensing is a feasible means to detect such aureoles. ?? 1993.</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://adsabs.harvard.edu/abs/2012AGUFM.H13G1444W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.H13G1444W"><span>Implications of Chloride, Boron, and Lithium in <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> of Jamaica, WI</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wishart, D.</p> <p>2012-12-01</p> <p>Chloride (Cl) often termed a "relatively conservative element" served as a very useful tracer (pathfinder element) in fluids from <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> by comparing its concentration to those of select ions in solution. The concentrations of major ions of three thermal spring water samples: Bath hot springs (BTHS and BTHN), Milk River (MKR), Windsor (WS) and a cold spring water sample-Salt River spring (SR) of Jamaica were plotted against the Cl concentration. Results of chemical analyses, graphical analyses, and hydrogeochemical modeling confirmed three water types: Na-Cl-SO4, Na-Cl, and Ca-Na-Cl. Whereas chloride concentrations at MKR, WS and SR strongly indicate the influence of sea water mixing, the concentrations at MKR and SR are spatially related to a major tectonic feature, the South Coast Fault Zone (SCFZ). A principal component analysis (PCA) performed for the water samples showed a direct correlation between the concentrations of chloride and other conservative elements: boron (B), lithium (Li), bromide (Br), strontium (Sr), arsenic (As), and cesium (Cs). Isotope results (δ18O, δ2H, 3H) of the water samples implied minimal shallow mixing with deep circulating thermal fluids at the Bath site and the predominance of mixing with deep-circulating brines at the WS, MKR, and SR sites. Ionic ratios (Cl/B, Br/Cl, Li/B, have provided further interesting results for these <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> including (1) a power series relationship between Li/B and SO4/Cl ratios; (2) the variation of B/Li versus Cl/SO4 concentrations with relatively prolonged water-rock contact time for these waters occurring at depth; and (3) low enthalpy. A discriminant analysis (DA) aided in the delineation of three independent <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> based on processes affecting the chemical compositions of the water samples. Calculated chloride convective heat fluxes range between compared to the boron flux range of 3.41 x 104 - 1.63 x 106 Calories/second.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFMOS41A0443C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFMOS41A0443C"><span>Exploring the Oceans for New <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span>: Collecting Stamps in the New Millenium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collier, R.; Lilley, M.; Cowen, J.</p> <p>2001-12-01</p> <p>Only a few years after helping to sample and characterize the first seafloor <span class="hlt">hydrothermal</span> vents, John Edmond frequently characterized continued vent exploration as "stamp collecting". But in fact, John was an avid explorer who helped expose the workings of the hydrosphere through observation. John showed us through his actions (if not always his words) that exploration, built on a strong scientific foundation, could lead to remarkable insights. The quest for new <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> still continues, often beginning with the characterization of <span class="hlt">hydrothermal</span> plumes in the water column. Although many of the tools and techniques are relatively well developed, the justification for this research and the modes of deployment have changed significantly. This presentation will summarize recent explorations of the Central Indian Ridge and southern East Pacific Rise, showing both the success of the primary goal -- to find new vents -- as well as the added value derived from the study of the <span class="hlt">hydrothermal</span> plumes themselves. In April, 2001, a study using the ROV Jason, deployed from the R/V Knorr (162-12), located and sampled new vent fields on the Central Indian Ridge (Van Dover et al., Science, 14 Sept., 2001). The primary goal of the expedition was to locate and characterize the vent communities as they may represent a unique connection between Atlantic and Pacific communities. The ship sailed with an interdisciplinary team ready to locate the vents and sample the biological community as well as their geological and geochemical environment within a single expedition. A series of nested CTD-transmissometer surveys, coupled with current measurements and chemical analyses for Fe, Mn, CH4, and H2 identified unequivocal <span class="hlt">hydrothermal</span> plumes and led to the discovery of a new vent field, named for John Edmond two weeks after he passed away in Boston. The combined application of physical, optical, and chemical properties allowed us to rapidly locate the vent within one hour of ROV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGP13A1284D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGP13A1284D"><span><span class="hlt">Hydrothermal</span> <span class="hlt">System</span> of the Lastarria Volcano (Central Andes) Imaged by Magnetotellurics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diaz, D.</p> <p>2015-12-01</p> <p>Lazufre volcanic complex, located in the central Andes, is recently undergoing an episode of uplift, conforming one of the most extensive deforming volcanic <span class="hlt">systems</span> worldwide. Recent works have focused on the subsurface of this volcanic <span class="hlt">system</span> at different scales, using surface deformation data, seismic noise tomography and magnetotellurics. Here we image the electrical resistivity structure of the Lastarria volcano, one of the most important features in the Lazufre area, using broadband magnetotelluric data at 30 locations around the volcanic edifice. Results from 3-D modeling show a conductive zone at 6 km depth south of the Lastarria volcano interpreted as a magmatic heat source, which is connected to a shallower conductive area beneath the volcanic edifice and its close vicinity. This shallow highly conductive zone fits with geochemical analysis results of thermal fluid discharges, related to fumaroles present in this area, in terms of depth extent and possible temperatures of fluids, and presents also a good correlation with seismic tomography results. The horizontal extension of this shallow conductive zone, related to the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Lastarria, suggests that it has been draining one of the lagoons in the area (Laguna Azufrera), forming a sulfur rich area which can be observed at the southern side of this lagoon. Joint modeling of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> using magnetotellurics and seismic data is part of the current work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-98PC-0983&hterms=Worms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DWorms','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-98PC-0983&hterms=Worms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DWorms"><span>NASA logo painted on orbiter <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1998-01-01</p> <p>A KSC worker paints the NASA logo on the port wing of the orbiter <span class="hlt">Endeavour</span>, which is scheduled to launch in December for STS-88. The paint is a special pigment that takes 18 hours to dry; the whole process takes approximately two weeks to complete. The NASA logo, termed 'meatball,' was originally designed in the late 1950s. It symbolized NASA's role in aeronautics and space in the early years of the agency. The original design included a white border surrounding it. The border was dropped for the Apollo 7 mission in October 1968, replaced with royal blue to match the background of the emblem. In 1972 the logo was replaced by a simple and contemporary design -- the 'worm' -- which was retired from use last year. NASA reverted to its original logo in celebration of the agency's 40th anniversary in October, and the 'golden age' of America's space program. All the orbiters will bear the new logo.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1777&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1777&hterms=rss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drss"><span>STS-97 <span class="hlt">Endeavour</span> after RSS rollback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>As dawn breaks on the horizon, Space Shuttle <span class="hlt">Endeavour</span> is seen standing ready for launch, targeted for 10:06 p.m. EST tonight on mission STS-97 to the International Space Station. The Rotating Service Structure was rolled back just before dawn. On top of the orange external tank is the Gaseous Oxygen Vent Arm and its vent hood, known as the '''beanie cap.''' The hood is raised to clear the external tank 2.5 minutes before launch. The orbiter carries the P6 Integrated Truss Segment containing solar arrays that will be temporarily installed to the Unity connecting module by the Z1 truss, recently delivered to and installed on the Station on mission STS-92. The two solar arrays are each more than 100 feet long. They will capture energy from the sun and convert it to power for the Station. Two spacewalks will be required to install the solar array connections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-01PP-0828&hterms=Space+race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSpace%2Brace','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-01PP-0828&hterms=Space+race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSpace%2Brace"><span>A perfect liftoff of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-100</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2001-01-01</p> <p>KENNEDY SPACE CENTER, Fla. - Flames from Space Shuttle <span class="hlt">Endeavour</span> light up the clouds as the Shuttle races into space on mission STS-100. Liftoff of <span class="hlt">Endeavour</span> on the ninth flight to the International Space Station occurred at 2:40:42 p.m. EDT. The 11- day mission will deliver and integrate the Spacelab Logistics Pallet/Launch Deployment Assembly, which includes the Space Station Remote Manipulator <span class="hlt">System</span> and the UHF Antenna. The mission includes two planned spacewalks for installation of the SSRMS on the Station. Also onboard is the Multi-Purpose Logistics Module Raffaello, carrying resupply stowage racks and resupply/return stowage platforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-01PP-0829&hterms=Space+race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSpace%2Brace','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-01PP-0829&hterms=Space+race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSpace%2Brace"><span>A perfect liftoff of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-100</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2001-01-01</p> <p>KENNEDY SPACE CENTER, Fla. - Space Shuttle <span class="hlt">Endeavour</span> leaps from Launch Pad 39A amid billows of smoke and steam as it races into space on mission STS-100. Liftoff of <span class="hlt">Endeavour</span> on the ninth flight to the International Space Station occurred at 2:40:42 p.m. EDT. The 11-day mission will deliver and integrate the Spacelab Logistics Pallet/Launch Deployment Assembly, which includes the Space Station Remote Manipulator <span class="hlt">System</span> and the UHF Antenna. The mission includes two planned spacewalks for installation of the SSRMS on the Station. Also onboard is the Multi-Purpose Logistics Module Raffaello, carrying resupply stowage racks and resupply/return stowage platforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JVGR..138..139F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JVGR..138..139F"><span>Miocene fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> associated with a volcanic complex in the Andes of central Chile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fuentes, Francisco; Aguirre, Luis; Vergara, Mario; Valdebenito, Leticia; Fonseca, Eugenia</p> <p>2004-11-01</p> <p>Cenozoic deposits in the Andes of central Chile have been affected by very low-grade burial metamorphism. At about 33°S in the Cuesta de Chacabuco area, approximately 53 km north of Santiago, two Oligocene and Miocene volcanic units form a ca. 1300-m-thick rock pile. The Miocene unit corresponds to a volcanic complex composed of two eroded stratovolcanoes. Secondary mineral assemblages in both units were studied petrographically and using X-ray diffraction and electron microprobe analyses. Most of the igneous minerals are wholly or partially preserved, and the ubiquitous secondary minerals are zeolites and mafic phyllosilicates. The alteration pattern observed is characterized by a lateral zonation in secondary mineralogy related to a lateral increase in temperature but not to stratigraphic depth. The following three zones were established, mainly based on the distribution of zeolites: zone I comprises heulandite, thomsonite, mesolite, stilbite and tri-smectite; zone II contains laumontite, yugawaralite, prehnite, epidote and chlorite; and zone III comprises wairakite, epidote, chlorite, diopside, biotite and titanite. For each zone, the following temperature ranges were estimated: zone I, 100-180 °C; zone II, 180-270 °C; and zone III, 245-310 °C. The alteration episode was characterized by a high Pfluid/ Ptotal ratio (ca. 1.0), although slightly variable, a high geothermal gradient of ca. 160 °C km -1 and fluid pressures below 500 bars. Although temperature was the main control on the mineral zonation, several interrelated parameters, mainly fluid composition, porosity and permeability, were also important. Hot, near neutral to slightly alkaline pH, alkali chloride <span class="hlt">hydrothermal</span> fluids with very low dissolved CO 2 contents deposited the secondary minerals. The alteration pattern is the result of depositing fluids in outflow regions from a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> developed inside a volcanic complex during the Miocene. The <span class="hlt">hydrothermal</span> <span class="hlt">system</span> has been eroded to a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V53E2881U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V53E2881U"><span>Volcanic Seismicity of La Soufrière Volcano (Guadeloupe, FWI): Interaction with <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ucciani, G.; Nercessian, A.; Bouin, M.; Beauducel, F.</p> <p>2012-12-01</p> <p>Our goal of this study is to characterize, spatially and temporally the seismicity of the La Soufrière volcano (Guadeloupe, FWI) and investigate the relationship between this seismicity andthe dynamics of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. We examine a set of 1777 volcanic earthquakes recorded by the permanent seismological monitoring network operated by the Volcanic and Seismological Observatory of Guadeloupe (OVSG-IPGP). This seismicity appears to be generated in a volume located at shallow depths under the volcano (maximum depth is 4km). The Observatory has classified volcanic earthquakes in three large groups: Volcano Tectonic events [VA] (760 events), Nested Volcanic events [VE] (922 events) and Monochromatic Volcanic events [VM] (140 events). We investigate the waveform similarity between earthquakes belonging to the same group by cross-correlation of the P phases. Results show a low similarity rate among earthquakes of the same groupe demonstrating that a refined classification is needed, which is in good agreement with a seismicity generated in a fractured medium by overpressure in the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. For VA and VE group, we use the similarity rates to distribute all events in different clusters by adjusting the selection threshold. With this method we show that both VA and VE events are present in all the clusters , and we conclude that similar seismic sources may generate this two types of events. For VM earthquakes, we observed different coda lengths and spectral features. To identify different clusters, we analyze these events with autoregressive method to determine resonance frequencies and factor Q. Based on results, we can infer that seismic events at La Soufrière volcano are related to two different source mechanisms: (1) fracturation processes of rocks and (2) resonance of cracks or conduits filled with <span class="hlt">hydrothermal</span> fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1978/1003/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1978/1003/report.pdf"><span>Methodology of determining the uncertainty in the accessible geothermal resource base of identified <span class="hlt">hydrothermal</span> convection <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nathenson, Manuel</p> <p>1978-01-01</p> <p>In order to quantify the uncertainty of estimates of the geothermal resource base in identified <span class="hlt">hydrothermal</span> convection <span class="hlt">systems</span>, a methodology is presented for combining estimates with uncertainties for temperature, area, and thickness of a geothermal reservoir into an estimate of the stored energy with uncertainty. Probability density functions for temperature, area, and thickness are assumed to be triangular in form. In order to calculate the probability distribution function for the stored energy in a single <span class="hlt">system</span> or in many <span class="hlt">systems</span>, a computer program for aggregating the input distribution functions using the Monte-Carlo method has been developed. To calculate the probability distribution of stored energy in a single <span class="hlt">system</span>, an analytical expression is also obtained that is useful for calibrating the Monte Carlo approximation. For the probability distributions of stored energy in a single and in many <span class="hlt">systems</span>, the central limit approximation is shown to give results ranging from good to poor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B12B..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B12B..02P"><span>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, <span class="hlt">Endeavour</span>, 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 <span class="hlt">Endeavour</span> 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://pubs.er.usgs.gov/publication/70030295','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030295"><span>Tertiary tilting and dismemberment of the laramide arc and related <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, Sierrita Mountain, Arizona</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Stavast, W.J.A.; Butler, R.P.; Seedorff, E.; Barton, M.D.; Ferguson, C.A.</p> <p>2008-01-01</p> <p>Multiple lines of evidence, including new and published geologic mapping and paleomagnetic and geobarometric determinations, demonstrate that the rocks and large porphyry copper <span class="hlt">systems</span> of the Sierrita Mountains in southern Arizona were dismembered and tilted 50?? to 60?? to the south by Tertiary normal faulting. Repetition of geologic features and geobarometry indicate that the area is segmented into at least three major structural blocks, and the present surface corresponds to oblique sections through the Laramide plutonic-<span class="hlt">hydrothermal</span> complex, ranging in paleodepth from ???1 to ???12 km. These results add to an evolving view of a north-south extensional domain at high angles to much extension in the southern Basin and Range, contrast with earlier interpretations that the Laramide <span class="hlt">systems</span> are largely upright and dismembered by thrust faults, highlight the necessity of restoring Tertiary rotations before interpreting Laramide structural and <span class="hlt">hydrothermal</span> features, and add to the broader understanding of pluton emplacement and evolution of porphyry copper <span class="hlt">systems</span>. ?? 2008 Society of Economic Geologists, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V31D0622L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V31D0622L"><span>Lead Isotopic Compositions of the <span class="hlt">Endeavour</span> Sulfides, 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>Labonte, F.; Hannington, M. D.; Cousens, B. L.; Blenkinsop, J.; Gill, J. B.; Kelley, D. S.; Lilley, M. D.; Delaney, J. R.</p> <p>2006-12-01</p> <p>32 sulfide samples from the main structures of the <span class="hlt">Endeavour</span> vent field, Juan de Fuca Ridge, were analyzed for their Pb isotope composition. The samples were collected from 6 main vent fields between 1985 and 2005 and encompass a strike length of more than 15 km along the ridge crest. The sulfides are typical of black smoker deposits on sediment-starved mid-ocean ridges. Pb isotope compositions of the massive sulfides within the six <span class="hlt">hydrothermal</span> fields vary within narrow ranges, with 206Pb/204Pb = 18.58 18.75, 207Pb/204Pb = 15.45 15.53 and 208Pb/204Pb = 37.84 38.10. A geographic trend is observed, with the lower Pb ratios restricted mostly to the northern part of the segment (Salty Dawg, Sasquatch and High Rise fields), and the higher Pb ratios restricted mostly to the southern part of the segment (Main <span class="hlt">Endeavour</span>, Clam Bed and Mothra fields). Variations within individual fields are much smaller than those between fields, and variation within individual sulfide structures is within the uncertainty of the measurements. Therefore, it is unlikely that the ranges of Pb isotope compositions along the length of the segment reflect remobilization, replacement, and recrystallization of sulfides, as suggested for the observed Pb isotope variability in some large seafloor sulfide deposits. Instead, the differences in isotopic compositions from north to south are interpreted to reflect differences in the source rocks exposed to <span class="hlt">hydrothermal</span> circulation of fluids below the seafloor. Possible sources of the somewhat more radiogenic Pb may be small amounts of buried sediment, either from turbidites or from hemipelagic sediment. This possibility is supported by high concentrations of CH4 and NHC4 found in the high-temperature vent fluids at the Main <span class="hlt">Endeavour</span> Field, which are interpreted to reflect subseafloor interaction between <span class="hlt">hydrothermal</span> fluids and organic material in buried sediments. However, the majority of the samples fall below and are approximately parallel to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21747174','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21747174"><span>Development of micro-flow <span class="hlt">hydrothermal</span> monitoring <span class="hlt">systems</span> and their applications to the origin of life study on Earth.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kawamura, Kunio</p> <p>2011-01-01</p> <p>Continuous extensive studies on thermophilic organisms have suggested that life emerged on <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on primitive Earth. Thus, it is well known that <span class="hlt">hydrothermal</span> reactions are, therefore, very important to study fields deeply related to the origin-of-life study. Furthermore, the importance of <span class="hlt">hydrothermal</span> and solvothermal <span class="hlt">systems</span> is now realized in both fundamental and practical areas. Here, our recent investigations are described for the development of real-time and in situ monitoring <span class="hlt">systems</span> for <span class="hlt">hydrothermal</span> reactions. The <span class="hlt">systems</span> were primarily developed for the origin-of-life study, but it was also applicable to fundamental and practical areas. The present techniques are based on the concept that a sample solution is injected to a narrow tubing flow reactor at high temperatures, where the sample is rapidly heated up in a very short time by exposure at to a high-temperature narrow tubing flow reactor with a very short time scale. This enables millisecond to second time-scale monitoring in real time and/or in situ at temperatures of up to 400°C. By using these techniques, a series of studies on the <span class="hlt">hydrothermal</span> origin-of-life have been successfully carried out.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1009306','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1009306"><span><span class="hlt">Hydrothermal</span> Processing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Elliott, Douglas C.</p> <p>2011-03-11</p> <p>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 <span class="hlt">hydrothermal</span> liquefaction and <span class="hlt">hydrothermal</span> gasification of biomass to fuels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B11J0571L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B11J0571L"><span>Insight from Genomics on Biogeochemical Cycles in a Shallow-Sea <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, G. S.; Amend, J.</p> <p>2015-12-01</p> <p>Shallow-sea <span class="hlt">hydrothermal</span> ecosystems are dynamic, high-energy <span class="hlt">systems</span> influenced by sunlight and geothermal activity. They provide accessible opportunities for investigating thermophilic microbial biogeochemical cycles. In this study, we report biogeochemical data from a shallow-sea <span class="hlt">hydrothermal</span> <span class="hlt">system</span> offshore Paleochori Bay, Milos, Greece, which is characterized by a central vent covered by white microbial mats with <span class="hlt">hydrothermally</span> influenced sediments extending into nearby sea grass area. Geochemical analysis and deep sequencing provide high-resolution information on the geochemical patterns, microbial diversity and metabolic potential in a two-meter transect. The venting fluid is elevated in temperature (~70oC), low in pH (~4), and enriched in reduced species. The geochemical pattern shows that the profile is affected by not only seawater dilution but also microbial regulation. The microbial community in the deepest section of vent core (10-12 cm) is largely dominated by thermophilic archaea, including a methanogen and a recently described Crenarcheon. Mid-core (6-8 cm), the microbial community in the venting area switches to the hydrogen utilizer Aquificae. Near the sediment-water interface, anaerobic Firmicutes and Actinobacteria dominate, both of which are commonly associated with subsurface and <span class="hlt">hydrothermal</span> sites. All other samples are dominated by diverse Proteobacteria. The sulfate profile is strongly correlated with the population size of delta- and episilon-proteobactia. The dramatic decrease in concentrations of As and Mn in pore fluids as a function of distance from the vent suggests that in addition to seawater dilution, microorganisms are likely transforming these and other ions through a combination of detoxification and catabolism. In addition, high concentrations of dissolved Fe are only measurable in the shallow sea grass area, suggesting that iron-transforming microorganisms are controlling Fe mobility, and promoting biomineralization. Taken</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812544B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812544B"><span>Resistivity structure of the Furnas <span class="hlt">hydrothermal</span> <span class="hlt">system</span> (Azores archipelago, Portugal) from AMT and ERT imaging.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Byrdina, Svetlana; Vandemeulebrouck, Jean; Rath, Volker; Silva, Catarina; Hogg, Colin; Kiyan, Duygu; Viveiros, Fatima; Eleuterio, Joana; Gresse, Marceau</p> <p>2016-04-01</p> <p>The Furnas volcanic complex is located in the eastern part of the São Miguel Island and comprises a 5 km × 8 km summit depression filled by two nested calderas with several craters and a lake. Present-day volcanic activity of Furnas volcano is mostly located in the northern part of the caldera, within the Furnas village and north to Furnas Lake, where <span class="hlt">hydrothermal</span> manifestations are mainly fumarolic fields, steam vents, thermal springs, and intense soil diffuse degassing. Considering the Furnas volcano as a whole, the total integrated CO2 efflux is extremely high, with a total amount of CO2 close to 1000 ton per day (Viveiros et al., 2009). We present the first results of an electrical resistivity tomography (ERT), combined with audio-magneto-telluric (AMT) measurements aligned along two profiles inside the caldera. The purpose of this survey is to delimit the extent, the geometry, and the depth of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> and to correlate the deep resistivity structure with high resolution cartography of diffuse CO2 flux (Viveiros et al, 2015). The ERT and AMT methods are complementary in terms of resolution and penetration depth: ERT can image the structural details of shallow <span class="hlt">hydrothermal</span> <span class="hlt">system</span> (down to 100 m in our study) while AMT can image at lower resolution deeper structures at the roots of a volcano (down to 4 km in our study). Our first independent 2D inversions of the ERT-AMT data show a good agreement between the surficial and deeper features. Below the main fumarole area we observe a low resistivity body (less than 1 Ohmm) which corresponds well to the high CO2 flux at the surface and is associated with an extended conductive body at larger depth. These results strongly suggest the presence of <span class="hlt">hydrothermal</span> waters at depth or/and the presence of altered clay-rich material. On a larger scale however, the geometry of the conducting zones differs slightly from what was expected from earlier surface studies, and may not be directly related to fault zones</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1735&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1735&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- Robotic arm experts begin inspection of a scrape on the surface of the honeycomb shell on <span class="hlt">Endeavour</span>'s robotic arm. The scrape occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1738&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1738&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- Robotic arm experts get ready for ultrasound testing on <span class="hlt">Endeavour</span>'s robotic arm. A scrape of the honeycomb shell around the arm occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1739&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1739&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- A piece of the honeycomb shell around <span class="hlt">Endeavour</span>'s robotic arm has been cut to inspect the arm. A scrape of the shell occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</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('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1736&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1736&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- Robotic arm experts begin inspection of a scrape on the surface of the honeycomb shell on <span class="hlt">Endeavour</span>'s robotic arm. The scrape occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22..</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990GeCoA..54.2811P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990GeCoA..54.2811P"><span>The boron isotope systematics of the Yellowstone National Park (Wyoming) <span class="hlt">hydrothermal</span> <span class="hlt">system</span>: A reconnaissance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palmer, M. R.; Sturchio, N. C.</p> <p>1990-10-01</p> <p>Boron concentrations and isotope compositions have been measured in fourteen hot spring waters, two drill hole waters, an unaltered rhyolite flow, and <span class="hlt">hydrothermally</span> altered rhyolite from the geothermal <span class="hlt">system</span> in Yellowstone National Park, Wyoming. The samples are representative of the major thermal areas within the park and span the range of fluid types. For the fluids, the B concentrations range from 0.043-2.69 mM/kg, and the δ11B values range from -9.3 to +4.4%.. There is no relationship between the dissolved B concentrations or isotope compositions with the concentration of any major element (other than Cl) or physical property. Each basin is characterized by a restricted range in B/Cl ratios and δ11B values. Hot spring waters from the Morris Basin, Upper Geyser Basin, Calcite Springs, and Clearwater have δ11B values close to that of unaltered rhyolite (-5.2%.) and are interpreted to have derived their B from this source. Waters from Mammoth Hot Springs, Sheepeater, and Rainbow Springs have lower δ11B values close to -8%.. These lower values may reflect leaching of B from sedimentary rocks outside the Yellowstone caldera, but they are similar to the δ11B value of <span class="hlt">hydrothermally</span> altered rhyolite (-9.7%.). Hence, the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited <span class="hlt">hydrothermal</span> minerals. Cooler springs along the Yellowstone River just outside the park boundary have lower B concentrations and higher δ11B values that may reflect mixing with shallow meteoric water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6026682','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6026682"><span>The boron isotope systematics of the Yellowstone National Park (Wyoming) <span class="hlt">hydrothermal</span> <span class="hlt">system</span>: A reconnaissance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Palmer, M.R. ); Sturchio, N.C. )</p> <p>1990-10-01</p> <p>Boron concentrations and isotope compositions have been measured in fourteen hot spring waters, two drill hole waters, an unaltered rhyolite flow, and <span class="hlt">hydrothermally</span> altered rhyolite from the geothermal <span class="hlt">system</span> in Yellowstone National Park, Wyoming. The samples are representative of the major thermal areas within the park and span the range of fluid types. For the fluids, the B concentrations range from 0.043-2.69 mM/kg, and the {delta}{sup 11}B values range from {minus}9.3 to +4.4{per thousand}. There is no relationship between the dissolved B concentrations or isotope compositions with the concentration of any major element (other than Cl) or physical property. Each basin is characterized by a restricted range in B/Cl ratios and {delta}{sup 11}B values. Hot spring waters from the Norris Basin, Upper Geyser Basin, Calcite Springs, and Clearwater have {delta}{sup 11}B values close to that of unaltered rhyolite ({minus}5.2{per thousand}) and are interpreted to have derived their B from this source. Waters from Mammoth Hot Springs, Sheepeater, and Rainbow Springs have lower {delta}{sup 11}B values close to {minus}8{per thousand}. These lower values may reflect leaching of B from sedimentary rocks outside the Yellowstone caldera, but they are similar to the {delta}{sup 11}B value of <span class="hlt">hydrothermally</span> altered rhyolite ({minus}9.7{per thousand}). Hence, the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited <span class="hlt">hydrothermal</span> minerals. Cooler springs along the Yellowstone River just outside the park boundary have lower B concentrations and higher {delta}{sup 11}B values that may reflect mixing with shallow meteoric water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23375572','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23375572"><span>Calibration of an acoustic <span class="hlt">system</span> for measuring 2-D temperature distribution around <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fan, Wei; Chen, Chen-Tung Arthur; Chen, Ying</p> <p>2013-04-01</p> <p>One of the fundamental purposes of quantitative acoustic surveys of seafloor <span class="hlt">hydrothermal</span> vents is to measure their 2-D temperature distributions. Knowing the <span class="hlt">system</span> latencies and the acoustic center-to-center distances between the underwater transducers in an acoustic tomography <span class="hlt">system</span> is fundamental to the overall accuracy of the temperature reconstruction. However, commercial transducer sources typically do not supply the needed data. Here we present a novel calibration algorithm to automatically determine the <span class="hlt">system</span> latencies and the acoustic center-to-center distances. The possible <span class="hlt">system</span> latency error and the resulting temperature error are derived and analyzed. We have also developed the experimental setup for calibration. To validate the effectiveness of the proposed calibration method, an experimental study was performed on acoustic imaging of underwater temperature fields in Lake Qiezishan, located at Longling County, Yunnan Province, China. Using the calibrated data, the reconstructed temperature distributions closely resemble the actual distributions measured with thermocouples, thus confirming the effectiveness of our algorithm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..171..301P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..171..301P"><span>Evolution of the Vesuvius magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> before the 16 December 1631 eruption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Principe, Claudia; Marini, Luigi</p> <p>2008-04-01</p> <p>In a recently published manuscript [Guidoboni, E., Boschi, E., 2006. Vesuvius before the 1631 eruption, EOS, 87(40), 417 and 423]; [Guidoboni, E. (Ed.), 2006. Pirro Ligorio, Libro di diversi terremoti (1571), volume 28, codex Ja II 15, Archivio di Stato di Torino, Edizione Nazionale delle Opere di Pirro Ligorio, Roma, De Luca, 261 pp], Pirro Ligorio gives a detailed description of the phenomena occurring in the crater area of Vesuvius volcano, in 1570-1571 and previous years. Here, these phenomena are interpreted as the first clearly documented signals of unrest of this volcanic <span class="hlt">system</span> caused by the shallow emplacement of a magma batch and leading to the 1631 eruption. Our interpretation is mainly based on the present understanding of the fluid geochemistry of magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. In this way, it is possible to conclude that: (i) incandescent rocks were present at the surface, with temperatures > 500 °C approximately and (ii) either a magmatic-dominated or a magmatic-<span class="hlt">hydrothermal</span>-type of conceptual geochemical model applies to Vesuvius in 1570-1571 and preceding years. The Ligorio's picture represents the first clear evidence that the magma involved in the 1631 eruption was present under the volcano more than sixty years before the eruption. Moreover, its emplacement produced a series of phenomena which were clearly observed although not understood at that time. A similar phenomenological pattern should be easily detected and correctly interpreted at present or in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3494924','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3494924"><span>Early Solar <span class="hlt">System</span> <span class="hlt">hydrothermal</span> activity in chondritic asteroids on 1–10-year timescales</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dyl, Kathryn A.; Bischoff, Addi; Ziegler, Karen; Young, Edward D.; Wimmer, Karl; Bland, Phil A.</p> <p>2012-01-01</p> <p>Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar <span class="hlt">System</span>. As undifferentiated objects, they also display widespread evidence of water–rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar <span class="hlt">System</span>, and the formation of prebiotic molecules. The timescales of water–rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water–rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from <span class="hlt">hydrothermal</span> conditions. The profiles were modeled at T = 800 °C and P(H2O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa-1Al-1 exchange in a fumarole. The geochemical data are consistent with <span class="hlt">hydrothermal</span> activity on the parent body lasting only 1–10 y. This result has wide-ranging implications for the geological history of chondritic asteroids. PMID:23093668</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23093668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23093668"><span>Early Solar <span class="hlt">System</span> <span class="hlt">hydrothermal</span> activity in chondritic asteroids on 1-10-year timescales.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dyl, Kathryn A; Bischoff, Addi; Ziegler, Karen; Young, Edward D; Wimmer, Karl; Bland, Phil A</p> <p>2012-11-06</p> <p>Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar <span class="hlt">System</span>. As undifferentiated objects, they also display widespread evidence of water-rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar <span class="hlt">System</span>, and the formation of prebiotic molecules. The timescales of water-rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water-rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from <span class="hlt">hydrothermal</span> conditions. The profiles were modeled at T = 800 °C and P(H(2)O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa(-1)Al(-1) exchange in a fumarole. The geochemical data are consistent with <span class="hlt">hydrothermal</span> activity on the parent body lasting only 1-10 y. This result has wide-ranging implications for the geological history of chondritic asteroids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V33C2772M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V33C2772M"><span>Changes in Vegetation Reflect Changes in the Mammoth Mountain and Long Valley Caldera <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murphy, F.; Diefenbach, A. K.; Evans, W.; Hurwitz, S.</p> <p>2013-12-01</p> <p>We examined aerial photographs of the area near Mammoth Lakes, CA taken from 1951 to the present, with the goal of determining if visible changes in vegetation might reflect changes in the upflow of gas or heat through the soil zone. Such changes could be related to magmatic intrusion, the development of geothermal resources, groundwater pumping, earthquakes, or to natural changes in the <span class="hlt">hydrothermal</span> flow <span class="hlt">system</span>. We examined the area near Horseshoe Lake at the southern base of Mammoth Mountain where diffuse emissions of carbon dioxide created extensive tree-kill in the 1990s. Analysis of photographs acquired in 1951 suggests that tree density in this area was lower than its surroundings at the time. Whether the low-density tree cover identified in the photographs indicates some lasting effects of a previous episode of tree mortality needs further investigation. We also examine possible effects of geothermal energy production at Casa Diablo that began operation in 1985 on vegetation along the western part of the resurgent dome of Long Valley Caldera. Previous studies have correlated tree-kill in this area with increased steam upflow from the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EP%26S...68..162T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EP%26S...68..162T"><span>Response of <span class="hlt">hydrothermal</span> <span class="hlt">system</span> to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taira, Taka'aki; Brenguier, Florent</p> <p>2016-10-01</p> <p>Time-lapse monitoring of seismic velocity at volcanic areas can provide unique insight into the property of <span class="hlt">hydrothermal</span> and magmatic fluids and their temporal variability. We established a quasi real-time velocity monitoring <span class="hlt">system</span> by using seismic interferometry with ambient noise to explore the temporal evolution of velocity in the Lassen Volcanic Center, Northern California. Our monitoring <span class="hlt">system</span> finds temporal variability of seismic velocity in response to stress changes imparted by an earthquake and by seasonal environmental changes. Dynamic stress changes from a magnitude 5.7 local earthquake induced a 0.1 % velocity reduction at a depth of about 1 km. The seismic velocity susceptibility defined as ratio of seismic velocity change to dynamic stress change is estimated to be about 0.006 MPa-1, which suggests the Lassen <span class="hlt">hydrothermal</span> <span class="hlt">system</span> is marked by high-pressurized <span class="hlt">hydrothermal</span> fluid. By combining geodetic measurements, our observation shows that the long-term seismic velocity fluctuation closely tracks snow-induced vertical deformation without time delay, which is most consistent with an hydrological load model (either elastic or poroelastic response) in which surface loading drives <span class="hlt">hydrothermal</span> fluid diffusion that leads to an increase of opening of cracks and subsequently reductions of seismic velocity. We infer that heated-<span class="hlt">hydrothermal</span> fluid in a vapor-dominated zone at a depth of 2-4 km range is responsible for the long-term variation in seismic velocity[Figure not available: see fulltext.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016607','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016607"><span><span class="hlt">Hydrothermal</span> ore-forming processes in the light of studies in rock- buffered <span class="hlt">systems</span>: II. Some general geologic applications</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hemley, J.J.; Hunt, J.P.</p> <p>1992-01-01</p> <p>The experimental metal solubilities for rock-buffered <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> provide important insights into the acquisition, transport, and deposition of metals in real <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> that produced base metal ore deposits. Water-rock reactions that determine pH, together with total chloride and changes in temperature and fluid pressure, play significant roles in controlling the solubility of metals and determining where metals are fixed to form ore deposits. Deposition of metals in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> occurs where changes such as cooling, pH increase due to rock alteration, boiling, or fluid mixing cause the aqueous metal concentration to exceed saturation. Metal zoning results from deposition occurring at successive saturation surfaces. Zoning is not a reflection simply of relative solubility but of the manner of intersection of transport concentration paths with those surfaces. Saturation surfaces will tend to migrate outward and inward in prograde and retrograde time, respectively, controlled by either temperature or chemical variables. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B13B0476L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B13B0476L"><span>Microbial heterotrophy coupled to Fe-S-As cycling in a shallow-sea <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, G.; Amend, J.</p> <p>2013-12-01</p> <p>To date, there are only a few known heterotrophic arsenite oxidizers and arsenate reducers. They utilize organic compounds as their carbon source and/or as important electron donors in the transfer arsenic in high temperature environments. Arsenic in <span class="hlt">hydrothermal</span> vent <span class="hlt">systems</span> can be immobilized at low temperatures through (ad)sorption on iron oxide and other iron-bearing minerals. Interactions with sulfur species can also affect the redox state of arsenic species. A better understanding of microbially-catalyzed reactions involving carbon, arsenic, iron and sulfur would provide constraints on the mobility of arsenic in a wide variety of natural and engineered <span class="hlt">systems</span>. The aim of this study is to establish links between microbial distribution and in situ Fe-S-As cycling processes in a shallow-sea <span class="hlt">hydrothermal</span> vent <span class="hlt">system</span>. We investigated three shallow-sea <span class="hlt">hydrothermal</span> vents, Champagne Hot Spring (CHS), Soufriere Spring (SOU) and Portsmouth Spring (PM), located off the western coast of Dominica, Lesser Antilles. CHS and SOU are characterized by moderate temperatures (46oC and 55oC, respectively), and PM is substantially hotter (~90-111 oC). Two sediment cores (one close to and one far from the thermal source) were collected from CHS and from SOU. Porewaters in both background cores had low concentrations of arsenic (mostly As3+, to a lesser extent As5+, DMA, MMA) and ferrous iron. The arsenic concentrations (predominantly As3+) in the CHS high temperature core were 30-90 nM, tracking with dissolved iron. Similar to CHS, the arsenic concentration in the SOU high temperature core was dominated by As3+ and controlled by ferrous iron. However, the arsenic concentration at SOU is comparatively higher, up to 1.9 mM. At the hotter and deeper PM site, highly elevated arsenic levels (1-2.5 mM) were measured, values that are among the highest arsenic concentrations ever reported in a marine <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Several autotrophic and heterotrophic media at two pHs (5.5 and 8</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3161S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3161S"><span>Sub-glacial Origin of the Hot Springs Bay Valley <span class="hlt">hydrothermal</span> <span class="hlt">System</span>, Akutan, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stelling, P. L.; Tobin, B.; Knapp, P.</p> <p>2015-12-01</p> <p>Exploration for geothermal energy in Hot Springs Bay Valley (HSBV) on Akutan Island, Alaska, has revealed a rich <span class="hlt">hydrothermal</span> history, including what appears to be a stage of peak activity during a significant glacial period. Alteration mineralogy observed in 754 m of drill core recovered from the outflow zone is dominated by chlorite and includes minor smectite clays, a suite of zeolite species and several moderately high-temperature <span class="hlt">hydrothermal</span> minerals (epidote/clinozoisite, prehnite, adularia and wairakite). The latter minerals each have minimum formation temperatures exceeding 200 oC, and fluid inclusion results in related calcite crystals indicate temperatures of formation to be as high as 275 oC, some 100 oC hotter than the modern boiling point with depth (BPD) curve at that depth (>62 m). In order to maintain liquid temperatures this high, the pressure during mineralization must have been substantially greater (~680 bar), a pressure change equivalent to erosion of ~280 m of rock (ρ=2.5 g/cm3). Although glacial erosion rates are too low (0.034 mm/yr; Bekele et al., 2003) for this amount of erosion to occur in a single glaciation, glacial melting and ablation are substantially more rapid (~100 mm/yr; Bekele et al., 2003; Person et al., 2012). Thus, a more probable scenario than pure erosion is that peak <span class="hlt">hydrothermal</span> conditions occurred during a large glacial event, with the added pressure from the overlying ice allowing the high temperature minerals to form closer to the ground surface. Subsequent melting of the ice eroded upper tributary valleys and upper levels of the originally smectite-rich alteration assemblage, explaining the paucity of swelling clays in the region. We present mineralogical, fluid inclusion and geochronologic evidence to support these conclusions, and discuss the general implications of sub-glacial <span class="hlt">hydrothermal</span> <span class="hlt">system</span> formation and geothermal resource potential. References: Bekele, E., Rostron, B. and Person, M. (2003) Fluid pressure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008MinDe..43..623H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008MinDe..43..623H"><span>Oxygen isotope mapping of the Archean Sturgeon Lake caldera complex and VMS-related <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, Northwestern Ontario, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holk, Gregory J.; Taylor, Bruce E.; Galley, Alan G.</p> <p>2008-08-01</p> <p>The <span class="hlt">hydrothermal</span> and magmatic evolution of the Sturgeon Lake caldera complex is graphically documented by a regional-scale (525 km2) analysis of oxygen isotopes. Spatial variations in whole-rock oxygen isotope compositions provide a thermal map of the cumulative effects of multiple stages of <span class="hlt">hydrothermal</span> metasomatism before, during, and after volcanogenic massive sulfide (VMS) mineralization. There is a progressive, upward increase in δ18O from less than 2‰ to greater than 15‰ through a 5-km-thick section above the Biedelman Bay subvolcanic intrusive complex. This isotopic trend makes it clear that at least the earlier phases of this intrusive complex were coeval with the overlying VMS-hosting cauldron succession and provided thermal energy to drive a convective <span class="hlt">hydrothermal</span> circulation <span class="hlt">system</span>. The sharp contrast in δ18O values between late stage phases of the Biedelman Bay intrusion and immediate hanging wall strata indicates that the main phase of VMS-related <span class="hlt">hydrothermal</span> activity took place before late-stage resurgence in the cauldron-related magmatic activity. Mineralogical and isotopic evidence indicates the presence of both syn- and postmineralization <span class="hlt">hydrothermal</span> activity defined by the presence of widespread semiconformable and more restricted discordant alteration zones that affect the pre- and syncauldron strata. The semiconformable alteration zones formed during early stages of <span class="hlt">hydrothermal</span> circulation and are defined by widespread silicification and carbonatization in association with relatively high δ18O values. The discordant alteration assemblages, containing Al-silicate minerals with chloritoid and/or Fe-rich carbonate or chlorite, centered on synvolcanic faults represent restricted zones of both seawater inflow and <span class="hlt">hydrothermal</span> fluid upflow. A rapid increase in δ18O values (˜7-9‰) over a short distance (<200 m) suggests marked cooling of <span class="hlt">hydrothermal</span> fluid from ˜350°C to less than 130°C either just before or during discharge onto the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..282...19D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..282...19D"><span>Evolution of a dynamic paleo-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> at Mangatete, Taupo Volcanic Zone, 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>Drake, Bryan D.; Campbell, Kathleen A.; Rowland, Julie V.; Guido, Diego M.; Browne, Patrick R. L.; Rae, Andrew</p> <p>2014-08-01</p> <p>Recent quarrying and active faulting at Mangatete, Taupo Volcanic Zone (TVZ), New Zealand, illuminate a rare spatial and temporal window on a dynamic Late Quaternary geothermal <span class="hlt">system</span>. Detailed geological mapping, stratigraphic logging, AMS 14C dating, and textural and mineralogical analyses were used to construct a complex history of <span class="hlt">hydrothermal</span>, volcanological and tectonic activity from ~ 36 to 2 ka. Extinct, surface <span class="hlt">hydrothermal</span> manifestations occur over a ~ 2 km2 area, and include in situ siliceous sinters distributed on normal fault terraces, an inferred <span class="hlt">hydrothermal</span> eruption breccia (HEB) containing acid-etched sinter blocks, another probable HEB that was bathed in silicifying thermal fluids, and sinter clasts that were entrained in a debris flow associated with a volcanic ash event. Preserved sinter textures typical of near-neutral pH, alkali chloride spring discharge channels, aprons, terraces and affiliated marshes comprise plant-rich, palisade, tufted bubble mat, and domal stromatolitic fabrics. In addition, a packed fragmental sinter facies is shown herein to constitute silicified microbial mats that were broken, transported and deposited as point bar deposits in thermal spring-fed streams. Moreover, four unusual siliceous sinter fabrics-vuggy, globular spongy, scalloped, and arcuate wavy layered-are interpreted to have formed from local acid-sulfate-chloride thermal springs, possibly associated with paleo-fumaroles. The reconstructed history of paleo-<span class="hlt">hydrothermal</span> activity indicates that the oldest sinters (~ 36 ka) at Mangatete developed in alkali chloride hot springs, but then underwent post-depositional alterion/overprinting by acid-sulfate steam condensate and were dismembered, possibly by a <span class="hlt">hydrothermal</span> eruption. Low pH hot-spring discharges forming the unusual, inferred acid sinter fabrics were localized in the same area. A shift in paleo-hydrology is evidenced by unaltered, alkali chloride sinters dated between ~ 22 and 3 ka. A cluster of sinter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5141380','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5141380"><span>Stochastic optimization of a <span class="hlt">hydro-thermal</span> <span class="hlt">system</span> including network constraints</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorenstin, B.G.; Campdonico, N.M.; Costa, J.P.; Pereira, M.V.F. )</p> <p>1992-05-01</p> <p>This paper describes a methodology for the optimal scheduling of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> taking into account multiple hydro reservoir characteristics, inflow stochasticity and transmission network represented by a linearized power flow model. The solution algorithm is based on stochastic dual dynamic programming, which decomposes the multi-stage stochastic problem into several one stage subproblems. Each subproblem corresponds to a linearized optimal power flow with additional constraints represented the hydro reservoir equations and a piecewise linear approximation of the expected future cost function. Each subproblem is solved by a customized network flow/Dual Simplex algorithm which takes advantage of the network characteristics of the hydro reservoirs and of the transmission <span class="hlt">system</span>. The application of the methodology is illustrated in a case study with a Brazilian <span class="hlt">system</span> comprising 44 hydroplants, 11 thermal plants, 463 buses and 834 circuits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5739009','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5739009"><span>Implementation of network flow programming to the <span class="hlt">hydrothermal</span> coordination in an energy management <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chaoan Li; Jap, P.J.; Streiffert, D.L. )</p> <p>1993-08-01</p> <p><span class="hlt">Hydrothermal</span> Coordination (HTC), consisting of hydro optimization and thermal unit commitment, is a major function in a power <span class="hlt">system</span> for allocating its generating resources to achieve the <span class="hlt">system</span>'s maximum economy. This paper is divided into two major parts. In the first part the optimality conditions of an Incremental Network Flow Programming (INFP) is described. In the second part the implementation of INFP in an EMS <span class="hlt">system</span> and its interface with the existing Unit Commitment (UC) software is presented. Some new features are described in detail. The combined HTC and UC package has been delivered to a power utility, Tenaga National Berhad (TNB) in West malaysia. ESCA's internal tests and Factory Acceptance Tests have shown that NFP with a modified Superkilter algorithm is a powerful tool for hydro network flow optimization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27457494','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27457494"><span>Volcano electrical tomography unveils edifice collapse hazard linked to <span class="hlt">hydrothermal</span> <span class="hlt">system</span> structure and dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique</p> <p>2016-07-26</p> <p>Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or mechanical weakening of the volcanic edifice often located above a low-strength detachment plane. The volume of altered rock available for collapse, the dynamics of the <span class="hlt">hydrothermal</span> fluid reservoir and the geometry of incipient collapse failure planes are key parameters for edifice stability analysis and modelling that remain essentially hidden to current volcano monitoring techniques. Here we derive a high-resolution, three-dimensional electrical conductivity model of the La Soufrière de Guadeloupe volcano from extensive electrical tomography data. We identify several highly conductive regions in the lava dome that are associated to fluid saturated host-rock and preferential flow of highly acid hot fluids within the dome. We interpret this model together with the existing wealth of geological and geochemical data on the volcano to demonstrate the influence of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> dynamics on the hazards associated to collapse-prone altered volcanic edifices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..286..303P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..286..303P"><span>Debris flow evolution and the activation of an explosive <span class="hlt">hydrothermal</span> <span class="hlt">system</span>; Te Maari, Tongariro, 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>Procter, J. N.; Cronin, S. J.; Zernack, A. V.; Lube, G.; Stewart, R. B.; Nemeth, K.; Keys, H.</p> <p>2014-10-01</p> <p>Analysis of the pre- and post-eruption topography, together with observations of the avalanche deposition sequence, yields a triggering mechanism for the 6 August 2012 eruption of Upper Te Maari. The avalanche was composed of a wedge of c. 683 000-774 000 m3 of coarse breccia, spatter and clay-rich tuffs and diamictons which slid from the western flanks of the Upper Te Maari Crater, the failure plane is considered to be a <span class="hlt">hydrothermally</span> altered clay layer. This landslide led to a pressure drop of up to 0.5 MPa, enough to generate an explosive eruption from the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> below, which had been activated over the months earlier by additional heat and gas from a shallow intrusion. The landslide transformed after c. 700 m into a clay-rich cohesive debris flow, eroding soils from steep, narrow stretches of channel, before depositing on intermediate broad flatter reaches. After each erosive reach, the debris flow contained greater clay and mud contents and became more mobile. At c. 2 km flow distance, however, the unsaturated flow stopped, due to a lack of excess pore pressure. This volume controlled flow deposited thick, steep sided lobes behind an outer levee, accreting inward and upward to form a series of curved surface ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6240083','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6240083"><span><span class="hlt">Hydrothermal</span> flow regime and magmatic heat source of the Cerro Prieto geothermal <span class="hlt">system</span>, Baja California, Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Elders, W.A.; Bird, D.K.; Schiffman, P.; Williams, A.E.</p> <p>1984-01-01</p> <p>This detailed three-dimensional model of the natural flow regime of the Cerro Prieto geothermal field, before steam production began, is based on patterns of <span class="hlt">hydrothermal</span> mineral zones and light stable isotopic ratios observed in rock samples from more than 50 deep wells, together with temperature gradients, wireline logs and other data. At the level so far penetrated by drilling, this <span class="hlt">hydrothermal</span> <span class="hlt">system</span> was heated by a thermal plume of water close to boiling, inclined at 45/sup 0/, rising from the northeast and discharging to the west. To the east a zone of cold water recharge overlies the inclined thermal plume. Fission track annealing studies show the reservoir reached 170/sup 0/C only 10/sup 4/ years ago. Oxygen isotope exchange data indicate that a 12 km/sup 3/ volume of rock subsequently reacted with three times its volume of water hotter than 200/sup 0/C. Averaged over the duration of the heating event this would require a flow velocity through a typical cross-section of the reservoir of about 6 m/year. The heat in storage in that part of the reservoir hotter than 200/sup 0/C and shallower than 3 km depth is equivalent to that which would be released by the cooling of about 1 or 2 km/sup 3/ of basalt or gabbro magma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4960541','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4960541"><span>Volcano electrical tomography unveils edifice collapse hazard linked to <span class="hlt">hydrothermal</span> <span class="hlt">system</span> structure and dynamics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique</p> <p>2016-01-01</p> <p>Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or mechanical weakening of the volcanic edifice often located above a low-strength detachment plane. The volume of altered rock available for collapse, the dynamics of the <span class="hlt">hydrothermal</span> fluid reservoir and the geometry of incipient collapse failure planes are key parameters for edifice stability analysis and modelling that remain essentially hidden to current volcano monitoring techniques. Here we derive a high-resolution, three-dimensional electrical conductivity model of the La Soufrière de Guadeloupe volcano from extensive electrical tomography data. We identify several highly conductive regions in the lava dome that are associated to fluid saturated host-rock and preferential flow of highly acid hot fluids within the dome. We interpret this model together with the existing wealth of geological and geochemical data on the volcano to demonstrate the influence of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> dynamics on the hazards associated to collapse-prone altered volcanic edifices. PMID:27457494</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://adsabs.harvard.edu/abs/2014EGUGA..16.7791J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.7791J"><span>Geophysical observations at natural and exploited <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in West Java, Indonesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jousset, Philippe; Sule, Rachmat; Diningrat, Wahyuddin; Gassner, Alexandra; Guichard, Sebastien; Kamil Syahbana, Devy; Abkar, Fanani; Ryannugroho, Riskiray; Hendryana, Andri; Kusnadi, Yosep; Nugraha, Andri; Umar, Muksin; Jaya, Makky; Erbas, Kemal</p> <p>2014-05-01</p> <p>We assess geothermal resources from our understanding of the structure and the dynamics of geothermal reservoirs and <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the south of Bandung. The co-existence of a large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and <span class="hlt">hydrothermal</span> processes in this area. We deployed a multidisciplinary geophysical network around geothermal areas in the south of Bandung, West Java, Indonesia. We deployed a network of 30 broadband and 4 short-period (1 Hz) seismic stations with Güralp and Trillium sensors (0.008 - 100 Hz) from October 2012 until December 2013. We extended the network in June 2013 with 16 short-period seismometers. Finally, we deployed a geodetic network including a continuously recording gravity meter, a GPS station, clinometers. We describe the set-up of the seismic and geodetic networks and we discuss first observations and results. As a first estimation of this excellent data set, we performed preliminary location of earthquakes using a non-linear algorithm, which allows us to define at least 3 seismic clusters. We use this first estimate to perform joint inversion tomography of hypocenters and velocity model. We discuss the found seismic pattern within the area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6319993','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6319993"><span>Deep borehole measurements for characterizing the magma/<span class="hlt">hydrothermal</span> <span class="hlt">system</span> at Long Valley Caldera, CA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carrigan, C.R.</p> <p>1989-01-01</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 site 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 <span class="hlt">system</span>. Goals of planned seismic experiments that involve the well include the investigation of local crystal 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. 9 refs., 5 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...629899R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...629899R"><span>Volcano electrical tomography unveils edifice collapse hazard linked to <span class="hlt">hydrothermal</span> <span class="hlt">system</span> structure and dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique</p> <p>2016-07-01</p> <p>Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or mechanical weakening of the volcanic edifice often located above a low-strength detachment plane. The volume of altered rock available for collapse, the dynamics of the <span class="hlt">hydrothermal</span> fluid reservoir and the geometry of incipient collapse failure planes are key parameters for edifice stability analysis and modelling that remain essentially hidden to current volcano monitoring techniques. Here we derive a high-resolution, three-dimensional electrical conductivity model of the La Soufrière de Guadeloupe volcano from extensive electrical tomography data. We identify several highly conductive regions in the lava dome that are associated to fluid saturated host-rock and preferential flow of highly acid hot fluids within the dome. We interpret this model together with the existing wealth of geological and geochemical data on the volcano to demonstrate the influence of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> dynamics on the hazards associated to collapse-prone altered volcanic edifices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V52A..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V52A..01S"><span>Ultramafic-hosted <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> 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> <span class="hlt">systems</span> 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 <span class="hlt">systems</span>. The Lost City <span class="hlt">hydrothermal</span> field (LCHF)(30°N) and the Rainbow <span class="hlt">hydrothermal</span> <span class="hlt">system</span> (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 sites along the northern MAR. In addition to deployment of conventional vent fluid sampling devices, in-situ chemical sensor <span class="hlt">systems</span> 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 <span class="hlt">system</span> 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/2016GeoRL..43.7953P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.7953P"><span>Three-dimensional electrical resistivity model of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in Long Valley Caldera, California, from magnetotellurics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peacock, J. R.; Mangan, M. T.; McPhee, D.; Wannamaker, P. E.</p> <p>2016-08-01</p> <p>Though shallow flow of <span class="hlt">hydrothermal</span> fluids in Long Valley Caldera, California, has been well studied, neither the <span class="hlt">hydrothermal</span> source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic <span class="hlt">system</span> and modeled in 3-D. The preferred electrical resistivity model suggests that the source reservoir is a narrow east-west elongated body 4 km below the west moat. The heat source could be a zone of 2-5% partial melt 8 km below Deer Mountain. Additionally, a collection of hypersaline fluids, not connected to the shallow <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, is found 3 km below the medial graben, which could originate from a zone of 5-10% partial melt 8 km below the south moat. Below Mammoth Mountain is a 3 km thick isolated body containing fluids and gases originating from an 8 km deep zone of 5-10% basaltic partial melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033475','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033475"><span>Diffuse flow <span class="hlt">hydrothermal</span> manganese mineralization along the active Mariana and southern Izu-Bonin arc <span class="hlt">system</span>, western Pacific</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hein, J.R.; Schulz, M.S.; Dunham, R.E.; Stern, R.J.; Bloomer, S.H.</p> <p>2008-01-01</p> <p>Abundant ferromanganese oxides were collected along 1200 km of the active Izu-Bonin-Mariana arc <span class="hlt">system</span>. Chemical compositions and mineralogy show that samples were collected from two deposit types: Fe-Mn crusts of mixed hydrogenetic/<span class="hlt">hydrothermal</span> origin and <span class="hlt">hydrothermal</span> Mn oxide deposits; this paper addresses only the second type. Mn oxides cement volcaniclastic and biogenic sandstone and breccia layers (Mn sandstone) and form discrete dense stratabound layers along bedding planes and within beds (stratabound Mn). The Mn oxide was deposited within coarse-grained sediments from diffuse flow <span class="hlt">systems</span> where precipitation occurred below the seafloor. Deposits were exposed at the seabed by faulting, mass wasting, and erosion. Scanning electron microscopy and microprobe analyses indicate the presence of both amorphous and crystalline 10 ?? and 7 ?? manganate minerals, the fundamental chemical difference being high water contents in the amorphous Mn oxides. Alternation of amorphous and crystalline laminae occurs in many samples, which likely resulted from initial rapid precipitation of amorphous Mn oxides from waxing pulses of <span class="hlt">hydrothermal</span> fluids followed by precipitation of slow forming crystallites during waning stages. The chemical composition is characteristic of a <span class="hlt">hydrothermal</span> origin including strong fractionation between Fe (mean 0.9 wt %) and Mn (mean 48 wt %) for the stratabound Mn, generally low trace metal contents, and very low rare earth element and platinum group element contents. However, Mo, Cd, Zn, Cu, Ni, and Co occur in high concentrations in some samples and may be good indicator elements for proximity to the heat source or to massive sulfide deposits. For the Mn sandstones, Fe (mean-8.4%) and Mn (12.4%) are not significantly fractionated because of high Fe contents in the volcaniclastic material. However, the proportion of <span class="hlt">hydrothermal</span> Fe (nondetrital Fe) to total Fe is remarkably constant (49-58%) for all the sample groups, regardless of the degree of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007MinDe..42..423P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007MinDe..42..423P"><span>PGE fractionation in seafloor <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: examples from mafic- and ultramafic-hosted <span class="hlt">hydrothermal</span> fields at the slow-spreading 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>Pašava, Jan; Vymazalová, Anna; Petersen, Sven</p> <p>2007-04-01</p> <p>The distribution of platinum group elements (PGEs) in massive sulfides and hematite-magnetite±pyrite assemblages from the recently discovered basalt-hosted Turtle Pits <span class="hlt">hydrothermal</span> 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 <span class="hlt">hydrothermal</span> <span class="hlt">system</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013OLEB...43...99C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013OLEB...43...99C"><span>Survivability and Abiotic Reactions of Selected Amino Acids in Different <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> Simulators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chandru, Kuhan; Imai, Eiichi; Kaneko, Takeo; Obayashi, Yumiko; Kobayashi, Kensei</p> <p>2013-04-01</p> <p>We tested the stability and reaction of several amino acids using <span class="hlt">hydrothermal</span> <span class="hlt">system</span> simulators: an autoclave and two kinds of flow reactors at 200-250 °C. This study generally showed that there is a variation in the individual amino acids survivability in the simulators. This is mainly attributed to the following factors; heat time, cold quenching exposure, metal ions and also silica. We observed that, in a rapid heating flow reactor, high aggregation and/or condensation of amino acids could occur even during a heat exposure of 2 min. We also monitored their stability in a reflow-type of simulator for 120 min at 20 min intervals. The non-hydrolyzed and hydrolyzed samples for this <span class="hlt">system</span> showed a similar degradation only in the absence of metal ions.</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>What is the constraint on formation of oil-starved <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> 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> <span class="hlt">systems</span> distribute, occurrence of <span class="hlt">hydrothermal</span> petroleum has not been found. In 2010 IODP Exp. 331 had been performed, and then five sites were drilled at the Iheya North <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. 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> <span class="hlt">system</span> 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> <span class="hlt">systems</span> 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/abs/2008E%26PSL.266..345P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26PSL.266..345P"><span>The effect of sulfur on vapor liquid fractionation of metals in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pokrovski, Gleb S.; Borisova, Anastassia Yu.; Harrichoury, Jean-Claude</p> <p>2008-02-01</p> <p>Despite the growing evidence that the vapor phase, formed through magma degassing and ore fluid boiling, can selectively concentrate and transport metals, the effects of major volatile components like sulfur, chlorine or carbon dioxide on the metal vapor-liquid fractionation and vapor-phase transport under magmatic-<span class="hlt">hydrothermal</span> conditions remain poorly known. We performed systematic experiments to investigate the effect of sulfur ligands on metal vapor-liquid partitioning in model H 2O-S-NaCl-KCl-NaOH <span class="hlt">systems</span> at temperatures from 350 to 500 °C. Results show that at acidic-to-neutral conditions, vapor-liquid equilibrium distribution coefficients, Km = mvapor / mliquid, where m is the mass concentration of the metal in corresponding phase, of metalloids (As, Sb) and base metals (Zn, Fe, Pb, Ag) are in the range 0.1-1.0 and 0.001-0.1, respectively, and are not significantly affected by the presence of geologically common sulfur concentrations, up to 1-3 wt.% S. In contrast, the partitioning of Cu, Au, and Pt into the vapor increases by a factor of 100 in comparison to the S-free water-salt <span class="hlt">system</span>, yielding Km values of 0.5-1.0, 1-10, and 10-20, respectively, due to formation of volatile neutral complexes with H 2S and, possibly, SO 2. In neutral-to-basic <span class="hlt">systems</span>, Zn, Pb, Fe and Ag show 10-100-fold increase of their partition coefficients, whereas Cu, Au and Pt exhibit Km values of up to several orders of magnitude lower, compared to acidic conditions at similar temperature, pressure and sulfur contents. These vapor-liquid distribution patterns result from combined effects of i) formation of volatile species with reduced sulfur ligands in the vapor phase, ii) changes in the metal speciation in the coexisting liquid phase as a function of pH, and iii) solute-solvent interactions in both phases. Our data explain the vapor-liquid fractionation trends for many metals as inferred in coexisting brine and vapor inclusions from magmatic-<span class="hlt">hydrothermal</span> deposits, and provide a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR41B2635C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR41B2635C"><span>Effects of chemical alteration on fracture mechanical properties in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Callahan, O. A.; Eichhubl, P.; Olson, J. E.</p> <p>2015-12-01</p> <p>Fault and fracture networks often control the distribution of fluids and heat in <span class="hlt">hydrothermal</span> and epithermal <span class="hlt">systems</span>, and in related geothermal and mineral resources. Additional chemical influences on conduit evolution are well documented, with dissolution and precipitation of mineral species potentially changing the permeability of fault-facture networks. Less well understood are the impacts of chemical alteration on the mechanical properties governing fracture growth and fracture network geometry. We use double-torsion (DT) load relaxation tests under ambient air conditions to measure the mode-I fracture toughness (KIC) and subcritical fracture growth index (SCI) of variably altered rock samples obtained from outcrop in Dixie Valley, NV. Samples from southern Dixie Valley include 1) weakly altered granite, characterized by minor sericite in plagioclase, albitization and vacuolization of feldspars, and incomplete replacement of biotite with chlorite, and 2) granite from an area of locally intense propylitic alteration with chlorite-calcite-hematite-epidote assemblages. We also evaluated samples of completely silicified gabbro obtained from the Dixie Comstock epithermal gold deposit. In the weakly altered granite KIC and SCI are 1.3 ±0.2 MPam1/2 (n=8) and 59 ±25 (n=29), respectively. In the propylitic assemblage KIC is reduced to 0.6 ±0.1 MPam1/2 (n=11), and the SCI increased to 75 ±36 (n = 33). In both cases, the altered materials have lower fracture toughness and higher SCI than is reported for common geomechanical standards such as Westerly Granite (KIC ~1.7 MPam1/2; SCI ~48). Preliminary analysis of the silicified gabbro shows a significant increase in fracture toughness, 3.6 ±0.4 MPam1/2 (n=2), and SCI, 102 ±45 (n=19), compared to published values for gabbro (2.9 MPam1/2 and SCI = 32). These results suggest that mineralogical and textural changes associated with different alteration assemblages may result in spatially variable rates of fracture</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003MinDe..38..443G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003MinDe..38..443G"><span>Composite synvolcanic intrusions associated with Precambrian VMS-related <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galley, Alan G.</p> <p>2003-06-01</p> <p> trondhjemite phases. The trondhjemite phases contain numerous internal contacts indicating emplacement as composite sills. Common structural features of the composite intrusions include early xenolith phases, abundant small comagmatic dikes, fractures and veins and, in places, columnar jointing. Internal phases may differ greatly in texture from fine- to coarse-grained, aphyric and granophyric through seriate to porphyritic. Mineralogical and isotopic evidence indicates that early phases of each composite intrusion are affected by pervasive to fracture-controlled high-temperature (350-450 °C) alteration reflecting seawater-rock interaction. Trondhjemite phases contain <span class="hlt">hydrothermal</span>-magmatic alteration assemblages within miarolitic cavities, <span class="hlt">hydrothermal</span> breccias and veins. This <span class="hlt">hydrothermal</span>-magmatic alteration may, in part, be inherited from previously altered wall rocks. Two of the four intrusions are host to Cu-Mo-rich intrusive breccias and porphyry-type mineralization which formed as much as 14 Ma after the main subvolcanic magmatic activity. The recognition of these Precambrian, subvolcanic composite intrusions is important for greenfields VMS exploration, as they define the location of thermal corridors within extensional oceanic-arc regimes which have the greatest potential for significant VMS mineralization. The VMS mineralization may occur for 2,000 m above the intrusions. In some cases, VMS mineralization has been truncated or enveloped by late trondhjemite phases of the composite intrusions. Evidence that much of the trondhjemitic magmatism postdates the principal VMS activity is a critical factor when developing heat and fluid flow models for these subseafloor magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V21A4737C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V21A4737C"><span>The Role of Siliceous <span class="hlt">Hydrothermal</span> Breccias in the Genesis of Volcanic Massive Sulphide Deposits - Ancient and Recent <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Costa, I. A.; Barriga, F. J.; Fouquet, Y.</p> <p>2014-12-01</p> <p>Siliceous <span class="hlt">hydrothermal</span> breccias were sampled in two Mid-Atlantic Ridge active sites: Lucky Strike and Menez Gwen. These <span class="hlt">hydrothermal</span> fields are located in the border of the Azorean plateau, southwest of the Azores islands where the alteration processes affecting basaltic rocks are prominent (Costa et al., 2003). The <span class="hlt">hydrothermal</span> breccias are genetically related with the circulation of low temperature <span class="hlt">hydrothermal</span> fluids in diffuse vents. The groundmass of these breccias precipitates from the fluid and consolidates the clastic fragments mostly composed of basalt. The main sources are the surrounding volcanic hills. Breccias are found near <span class="hlt">hydrothermal</span> vents and may play an important role in the protection of subseafloor <span class="hlt">hydrothermal</span> deposits forming an impermeable cap due to the high content in siliceous material. The amorphous silica tends to precipitate when the fluid is conductively cooled as proposed by Fouquet et al. (1998) after Fournier (1983). The process evolves gradually from an initial stage where we have just the fragments and circulating seawater. The ascending <span class="hlt">hydrothermal</span> fluid mixes with seawater, which favours the precipitation of the sulphide components. Sealing of the initially loose fragments begins, the temperature rises below this crust, and the processes of mixing fluid circulation and conductive cooling are simultaneous. At this stage the fluid becomes oversaturated with respect to amorphous silica. This form of silica can precipitate in the open spaces of the porous sulphides and seal the <span class="hlt">system</span>. Normally this can happen at low temperatures. At this stage the <span class="hlt">hydrothermal</span> breccia is formed creating a progressively less permeable, eventually impermeable cap rock at the surface. Once the fluid is trapped under this impermeable layer, conductive cooling is enhanced and mixing with seawater is restricted, making the precipitation of amorphous silica more efficient. Since the first discovery and description of recent mineralized submarine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1808&hterms=watch&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwatch','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1808&hterms=watch&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwatch"><span>STS-113 visitors watch the Space Shuttle <span class="hlt">Endeavour</span> launch</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. - Watching the launch of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-113 are NASA Administrator Sean O'Keefe (left) and Associate Administrator of Public Affairs Glen Mahone. Liftoff occurred ontime at 7:49:47 p.m. EST. The launch is the 19th for <span class="hlt">Endeavour</span>, and the 112th flight in the Shuttle program. Mission STS-113 is the 16th assembly flight to the International Space Station, carrying another structure for the Station, the P1 integrated truss. Also onboard are the Expedition 6 crew, who will replace Expedition 5. <span class="hlt">Endeavour</span> is scheduled to land at KSC after an 11-day journey.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V31B4749K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V31B4749K"><span>Compressional and Shear Wave Structure of the Upper Crust Beneath the <span class="hlt">Endeavour</span> 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>Kim, E.; Toomey, D. R.; Hooft, E. E. E.; Wilcock, W. S. D.; Weekly, R. T.; Lee, S. M.; Kim, Y.</p> <p>2014-12-01</p> <p>We present tomographic images of the compressional (Vp) and shear (Vs) wave velocity structure of the upper crust beneath the <span class="hlt">Endeavour</span> segment of the Juan de Fuca Ridge. This ridge segment is bounded by the <span class="hlt">Endeavour</span> and Cobb overlapping spreading centers (OSCs) to the north and south, respectively. Near the segment center an axial magma chamber (AMC) reflector underlies 5 <span class="hlt">hydrothermal</span> vent fields. Our analysis uses data from the <span class="hlt">Endeavour</span> tomography (ETOMO) experiment. A prior study of the Vp structure indicates that the shallow crust of the <span class="hlt">Endeavour</span> segment is strongly heterogeneous [Weekly et al., 2014]. Beneath the OSCs Vp is anomalously low, indicating tectonic fracturing. Near the segment center, upper crustal Vp is relatively high beneath the <span class="hlt">hydrothermal</span> vent fields, likely due to infilling of porosity by mineral precipitation. Lower velocities are observed immediately above the AMC, reflecting increased fracturing or higher temperatures. Anisotropic tomography reveals large amplitude ridge-parallel seismic anisotropy on-axis (>10%), but decreases in the off-axis direction over 5-10 km. Here we use crustal S-wave phases (Sg) — generated by P-to-S conversions near the seafloor — to better constrain crustal properties. Over half the OBSs in the ETOMO experiment recorded horizontal data on two channels that are of sufficiently high quality that we can orient the geophones using the polarizations of water waves from shots within 12 km. For these OBSs, crustal Sg phases are commonly visible out to ranges of ~20-25 km. We invert the Sg data separately for Vs structure, and also jointly invert Pg and Sg data to constrain the Vp/Vs ratio. Preliminary inversions indicate that Vs and Vp/Vs varies both laterally and vertically. These results imply strong lateral variations in both the physical (e.g., crack density and aspect ratio) and chemical (e.g., hydration) properties of oceanic crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/505161','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/505161"><span>Fluid inclusion and isotopic systematics of an evolving magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moore, J.N.; Gunderson, R.P.</p> <p>1995-10-01</p> <p>The Geysers, California, is the site of a long-lived <span class="hlt">hydrothermal</span> <span class="hlt">system</span> that initially developed 1.5-2 m.y. ago in response to the intrusion of a hypabyssal granitic pluton. Although wells drilled into The Geysers produce only dry steam, fluid inclusion, isotopic, and mineralogic data demonstrate that the present vapor-dominated regime evolved from an earlier and more extensive, liquid-dominated <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Circulation of these early fluids produced veins characterized by tourmaline {+-} biotite {+-} actinolite {+-} clinopyroxene within the pluton and adjacent biotite-rich hornfels, actinolite {+-} ferroaxinite {+-} epidote and epidote {+-} chlorite within the intermediate parts of the thermal <span class="hlt">system</span> and calcite in the outer parts. Potassium feldspar and quartz are present in all assemblages. Pressure-corrected homogenization temperatures and apparent salinities of fluid inclusions trapped in vein minerals range from 440{degrees}C and 44 wt% NaCl equivalent within the hornfels (<600 m from the pluton) to 325{degrees}C and 5 wt% NaCl equivalent at distances of approximately 1500 m from the intrusion. We suggest that the shallow, moderate salinity fluids are connate waters modified by water-rock interactions while the high-salinity fluids are interpreted as magmatic brines. Halite-dissolution temperatures of inclusions in the hornfels and pluton indicate that the magnetic fluids were trapped at lithostatic pressures (300-900 bars). In contrast, homogenization temperatures of the connate fluids suggest trapping under hydrostatic pressures of less than several hundred bars. Whole-rock {delta}{sup 18}O values of samples from The Geysers display systematic variations with respect to depth, location within the field, and grade of alteration. At depths below +610 m relative to mean sea level, the {delta}{sup 18}O values are strongly zoned around a northwest-southeast trending low located near the center of the steam reservoir. 77 refs., 15 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984GeCoA..48..177V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984GeCoA..48..177V"><span>The speciation of mercury in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, with applications to ore deposition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varekamp, Johan C.; Buseck, Peter R.</p> <p>1984-01-01</p> <p>Hg in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is generally thought to be transported as Hg-S complexes. However, the abundance of Hg 0vap, in geothermal emissions suggests that Hg 0eq, is present in the liquid phase of geothermal <span class="hlt">systems</span>. Calculations for reducing fluids (HS - dominant over SO =4) in equilibrium with cinnabar indicate that Hg 0eq, can be quite abundant relative to other species at temperatures above 200°C. Increasing pH and temperature, and decreasing total S, ionic strength, and pO 2 all promote the abundance of Hg 0eq. When a vapor phase develops from a geothermal liquid, Hg partitions strongly into the vapor as Hg 0vap. Vapor transport at shallow level then results in the formation of Hg halos around shallow aquifers as well as in a flux of Hg to the atmosphere. Hg deposition may occur in response to mixing with oxidizing or acidic water, turning Hg 0eq, into Hg ++, with subsequent cinnabar precipitation. When pyrite is the stable Fe-sulfide, cinnabar solubility is at its lowest, so cinnabar + pyrite assemblages are common. Cinnabar + hematite ± pyrite can precipitate from more oxidized or S-poor water. Hg 0liq, can occur as a primary mineral, in coexistence with all common Fe-sulfides and oxides. Cinnabar ± Hg 0liq cannot coexist with pyrrhotite or magnetite at temperatures between 100° and 250°C. Evidence from Hg deposits indicates that many formed from dilute <span class="hlt">hydrothermal</span> fluids in which Hg probably occurred as Hg 0eq. In S-rich <span class="hlt">systems</span>, Hg may occur as Hg-S complexes, and in saline waters it can occur as Hg-Cl complexes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020068','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020068"><span>Rare earth element metasomatism in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: The Willsboro-Lewis wollastonite ores, New York, 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>Whitney, P.R.; Olmsted, J.F.</p> <p>1998-01-01</p> <p>Wollastonite ores and garnet-pyroxene skarns in the Willsboro-Lewis district, New York, USA were formed in a complex <span class="hlt">hydrothermal</span> <span class="hlt">system</span> associated with the emplacement of a large anorthosite pluton. Contact-metamorphic marbles were replaced by wollastonite, garnet, and clinopyroxene during infiltration metasomatism involving large volumes of water of chiefly meteoric origin. Rare earth elements (REE) in these rocks show large departures from the protolith REE distribution, indicative of substantial REE mobility. Three types of chondrite-normalized REE distribution patterns are present. The most common, found in ores and skarns containing andradite-rich garnet, is convex-up in the light REE (LREE) with a maximum at Pr and a positive Eu anomaly. Europium anomalies and Pr/Yb ratios are correlated with X(Ad) in garnet. This pattern (type C) results from uptake of REE from <span class="hlt">hydrothermal</span> fluids by growing crystals of calcsilicate minerals, principally andradite, with amounts of LREE controlled by the difference in ionic radius between Ca++ and REE3+ in garnet X sites. The Eu anomaly results either from prior interaction of the fluids with plagioclase-rich, Eu-positive anorthositic rocks in and near the ore zone, or by enrichment of divalent Eu on growth surfaces of garnet followed by entrapment, or both. Relative enrichment in heavy REE (type H) occurs in ores and skarn where calcsilicates, including grossularitic garnet, in contact-metamorphic marble have been concentrated by dissolution of calcite. In most cases a negative Eu anomaly is inherited from the marble protolith. Skarns containing titanite and apatite exhibit high total REE, relative light REE enrichment, and negative Eu anomalies (type L). These appear to be intrusive igneous rocks (ferrodiorites or anorthositic gabbros) that have been converted to skarn by Ca metasomatism. REE, sequestered in titanite, apatite, and garnet, preserve the approximate REE distribution pattern of the igneous protolith. Post</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/887171','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/887171"><span>Vapliq <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, and the vertical permeability of Los Azufres, Mexico, geothermal reservoir</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Iglesias, Eduardo R.; Arellano, Victor M.</p> <p>1988-01-01</p> <p>We identify a new category of natural <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> intermediate between liquid- and vapor-dominated. This category is characterized by a “vapliq” vertical pressure profile, which is nearly vaporstatic in the shallower portion of the <span class="hlt">system</span>, and nearly boiling-point-for-depth at depth. The prototype of these <span class="hlt">systems</span> is the geothermal field of Los Azufres, Mexico. To explore the thermohydrological conditions conducent to this type of <span class="hlt">system</span>, we propose a 1-D vertical scenario based on generally accepted conceptual models of liquid- and vapor-dominated geothermal reservoirs. We use the corresponding mass and thermal energy transport equations to establish that a necessary condition for the existence of 2-phase <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is that the absolute value of the vertical thermal flux must exceed Q{sub min}, a parameter that depends only on the values of the pressure and of the thermal conductivity at the boiling point of the <span class="hlt">system</span>. The values of Q{sub min} are typically 1-4 times the average terrestrial flux. We also find that geothermal <span class="hlt">systems</span> in which convective heat transport is accomplished by the well-known heat-pipe mechanism can exist only if the corresponding heat flux exceeds Q{sub min} and the permeability at the boiling point of the <span class="hlt">system</span> is smaller than k{sub Bmax}, a parameter that depends only on the values of the pressure and of the thermal conductivity at the boiling point. Typical values of k{sub Bmax} are 1-3 {times} 10{sup -18} m{sup 2}, suggesting a reason for the fact that all vapor-dominated <span class="hlt">systems</span> are associated with very-low matrix permeability formations. Applying these insights, and the mass and heat transport equations to Los Azufres, we conclude that a contrast of 1-3 orders of magnitude exists between the vertical permeability at the boiling point and that corresponding to the vapor-dominated portion of the <span class="hlt">system</span>. We propose that similar permeability contrasts may be responsible for the characteristic composite pressure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18818356','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18818356"><span>The structure and dynamics of mid-ocean ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coumou, D; Driesner, T; Heinrich, C A</p> <p>2008-09-26</p> <p>Sub-seafloor <span class="hlt">hydrothermal</span> convection at mid-ocean ridges transfers 25% of the Earth's heat flux and can form massive sulfide ore deposits. Their three-dimensional (3D) structure and transient dynamics are uncertain. Using 3D numerical simulations, we demonstrated that convection cells self-organize into pipelike upflow zones surrounded by narrow zones of focused and relatively warm downflow. This configuration ensures optimal heat transfer and efficient metal leaching for ore-deposit formation. Simulated fluid-residence times are as short as 3 years. The concentric flow geometry results from nonlinearities in fluid properties, and this may influence the behavior of other fluid-flow <span class="hlt">systems</span> in Earth's crust.</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://www.osti.gov/scitech/servlets/purl/888652','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/888652"><span>The long term observed effect of air and water injection into a fracture <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mario Cesar Suarez Arriaga; Mirna Tello Lopez; Luis de Rio; Hector Gutierrez Puente</p> <p>1992-01-01</p> <p>Injection of atmospheric air mixed with waste reinjection liquid, has been occurring since 1982 at the Los Azufres, Mexico volcanic <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Several chemical and thermodynamical evidences show that air injection into this fractured geothermal field, could be considered as a long term natural tracer test. Nitrogen and Argon separated from the air mixture migrate from reinjection wells to production zones following preferential paths closely related to high permeability conduits. These paths can be detected, looking into the N2 solubility evolution of production wells. The anisotropic nature of the fractured volcanic rock, would demand considerably amounts of artificial tracer in order to be detected at the producing wells, specially when fluid extraction is low. This explains the unsuccessful recovery of the artificial tracer tests performed in past years at Tejamaniles, the southern field's sector. On the other hand, chloride concentrations and other salts, are increasing in the liquid produced by the oldest wells of the sector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/887480','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/887480"><span>The use of air as a natural tracer infractured <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, Los Azufres, Mexico, case study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mario Cesar Sudrez Arriaga; Hector Gutierrez Puente, Josefina Moreno Ochoa</p> <p>1991-01-01</p> <p>Injection of atmospheric air mixed with cold water has been occurring since 1982 at the Los Azufres geothermal field. Several chemical and thermodynamical evidences show that air injection into this fractured <span class="hlt">hydrothermal</span> <span class="hlt">system</span> could be considered as a long term natural tracer test. Nitrogen and Argon separated from the air mixture migrate, under the action of the induced injection-extraction gradient, from reinjection sectors to production zones following preferential paths closely related to high permeability conduits. A coarse numerical estimation of the average permeability tensor existing at Tejamaniles, the southern sector, explains the unsuccessful recovery of the artificial tracer tests performed in past years: the anisotropic nature of the fractured volcanic rock would demand considerably quantities of tracer in order to be detected at the producing wells, especially when fluid extraction was low. At the same time concentrations of calcium, cesium, chloride, potassium, rubidium and sodium, are increasing in the liquid produced by the oldest wells of this field's sector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1977/0060/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1977/0060/report.pdf"><span>A theoretical analysis of fluid flow and energy transport in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Faust, Charles R.; Mercer, James W.</p> <p>1977-01-01</p> <p>A mathematical derivation for fluid flow and energy transport in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is presented. Specifically, the mathematical model describes the three-dimensional flow of both single- and two-phase, single-component water and the transport of heat in porous media. The derivation begins with the point balance equations for mass, momentum, and energy. These equations are then averaged over a finite volume to obtain the macroscopic balance equations for a porous medium. The macroscopic equations are combined by appropriate constitutive relationships to form two similified partial differential equations posed in terms of fluid pressure and enthalpy. A two-dimensional formulation of the simplified equations is also derived by partial integration in the vertical dimension. (Woodard-USGS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5319546','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5319546"><span>A core hole into the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of the Long Valley caldera</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wollenberg, H.; White, A.; Flexser, S.; Sorey, M.; Farrar, C.</p> <p>1987-03-01</p> <p>To investigate the present-day <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, the ''Shady Rest'' hole was continuously cored 715m into the southwestern moat of the Long Valley caldera. The hole intersected 100m of glacial till and 300m of postcaldera rhyolite before entering the welded Bishop Tuff and bottoming in that unit. A sharp temperature rise over the upper 350m, and near-isothermal conditions below reflect the presence of approx.200/sup 0/C water moving through open, calcite-lined fractures in silicified Early Rhyolite and Bishop Tuff. The depth to the Bishop is the shallowest encountered in holes in the caldera, and the temperatures measured are among the hottest observed in wells drilled within the caldera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012NHESS..12.2259R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012NHESS..12.2259R"><span>Multi-parametric investigation of the volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> at Tatun Volcano Group, Northern Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rontogianni, S.; Konstantinou, K. I.; Lin, C.-H.</p> <p>2012-07-01</p> <p>The Tatun Volcano Group (TVG) is located in northern Taiwan near the capital Taipei. In this study we selected and analyzed almost four years (2004-2007) of its seismic activity. The seismic network established around TVG initially consisted of eight three-component seismic stations with this number increasing to twelve by 2007. Local seismicity mainly involved high frequency (HF) earthquakes occurring as isolated events or as part of spasmodic bursts. Mixed and low frequency (LF) events were observed during the same period but more rarely. During the analysis we estimated duration magnitudes for the HF earthquakes and used a probabilistic non-linear method to accurately locate all these events. The complex frequencies of LF events were also analyzed with the Sompi method indicating fluid compositions consistent with a misty or dusty gas. We juxtaposed these results with geochemical/temperature anomalies extracted from fumarole gas and rainfall levels covering a similar period. This comparison is interpreted in the context of a model proposed earlier for the volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> of TVG where fluids and magmatic gases ascend from a magma body that lies at around 7-8 km depth. Most HF earthquakes occur as a response to stresses induced by fluid circulation within a dense network of cracks pervading the upper crust at TVG. The largest (ML ~ 3.1) HF event that occurred on 24 April 2006 at a depth of 5-6 km had source characteristics compatible with that of a tensile crack. It was followed by an enrichment in magmatic components of the fumarole gases as well as a fumarole temperature increase, and provides evidence for ascending fluids from a magma body into the shallow <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. This detailed analysis and previous physical volcanology observations at TVG suggest that the region is volcanically active and that measures to mitigate potential hazards have to be considered by the local authorities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=60PEzue7LXY','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=60PEzue7LXY"><span>Final Ferry Takes SCA-<span class="hlt">Endeavour</span> Over Los Angeles</span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>Space shuttle <span class="hlt">Endeavour</span> atop NASA's Shuttle Carrier Aircraft overflew many landmarks in Los Angeles to conclude its final ferry flight into history on Sept. 21, 2012. Among highlights in this video...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1803&hterms=majestic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmajestic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1803&hterms=majestic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmajestic"><span>Liftoff of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-97</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>As Space Shuttle <span class="hlt">Endeavour</span> rockets off Launch Pad 39B, spewing clouds of smoke and steam, a majestic heron soars over the nearby water and <span class="hlt">Endeavour'''s</span> reflection. Liftoff occurred on time at 10:06:01 p.m. EST. The Shuttle and its five-member crew will deliver U.S. solar arrays to the International Space Station and be the first Shuttle crew to visit the Station'''s first resident crew. The 11-day mission includes three spacewalks. This marks the 101st mission in Space Shuttle history and the 25th night launch. <span class="hlt">Endeavour</span> is expected to land Dec. 11 at 6:19 p.m. EST.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21A1469R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21A1469R"><span>Cameras on the NEPTUNE Canada seafloor observatory: Towards monitoring <span class="hlt">hydrothermal</span> vent ecosystem dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robert, K.; Matabos, M.; Sarrazin, J.; Sarradin, P.; Lee, R. W.; Juniper, K.</p> <p>2010-12-01</p> <p><span class="hlt">Hydrothermal</span> vent environments are among the most dynamic benthic habitats in the ocean. The relative roles of physical and biological factors in shaping vent community structure remain unclear. Undersea cabled observatories offer the power and bandwidth required for high-resolution, time-series study of the dynamics of vent communities and the physico-chemical forces that influence them. The NEPTUNE Canada cabled instrument array at the <span class="hlt">Endeavour</span> <span class="hlt">hydrothermal</span> vents provides a unique laboratory for researchers to conduct long-term, integrated studies of <span class="hlt">hydrothermal</span> vent ecosystem dynamics in relation to environmental variability. Beginning in September-October 2010, NEPTUNE Canada (NC) will be deploying a multi-disciplinary suite of instruments on the <span class="hlt">Endeavour</span> Segment of the Juan de Fuca Ridge. Two camera and sensor <span class="hlt">systems</span> will be used to study ecosystem dynamics in relation to <span class="hlt">hydrothermal</span> discharge. These studies will make use of new experimental protocols for time-series observations that we have been developing since 2008 at other observatory sites connected to the VENUS and NC networks. These protocols include sampling design, camera calibration (i.e. structure, position, light, settings) and image analysis methodologies (see communication by Aron et al.). The camera <span class="hlt">systems</span> to be deployed in the Main <span class="hlt">Endeavour</span> vent field include a Sidus high definition video camera (2010) and the TEMPO-mini <span class="hlt">system</span> (2011), designed by IFREMER (France). Real-time data from three sensors (O2, dissolved Fe, temperature) integrated with the TEMPO-mini <span class="hlt">system</span> will enhance interpretation of imagery. For the first year of observations, a suite of internally recording temperature probes will be strategically placed in the field of view of the Sidus camera. These installations aim at monitoring variations in vent community structure and dynamics (species composition and abundances, interactions within and among species) in response to changes in environmental conditions at different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70168949','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70168949"><span>Context of ancient aqueous environments on Mars from in situ geologic mapping at <span class="hlt">Endeavour</span> Crater</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Crumpler, L.S.; Arvidson, R. E.; Bell, J.; Clark, B. C.; Cohen, B. A.; Farrand, W. H.; Gellert, Ralf; Golombek, M.; Grant, J. A.; Guinness, E.; Herkenhoff, Kenneth E.; Johnson, J. R.; Jolliff, B.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T.; Rice, J. W.; Squyres, S. W.; Sullivan, R.; Yen, A. S.</p> <p>2015-01-01</p> <p>Using the Mars Exploration Rover Opportunity, we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22 km diameter <span class="hlt">Endeavour</span> Crater (Latitude −2°16′33″, Longitude −5°10′51″). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rocks distinguishes four mappable bedrock lithologic units. Three of these rock units predate the surrounding Burns formation sulfate-rich sandstones and one, the Matijevic Formation, represents conditions on early Mars predating the formation of <span class="hlt">Endeavour</span> Crater. The stratigraphy assembled from these observations includes several geologic unconformities. The differences in lithologic units across these unconformities record changes in the character and intensity of the Martian aqueous environment over geologic time. Water circulated through fractures in the oldest rocks over periods long enough that texturally and elementally significant alteration occurred in fracture walls. These oldest pre-<span class="hlt">Endeavour</span> rocks and their network of mineralized and altered fractures were preserved by burial beneath impact ejecta and were subsequently exhumed and exposed. The alteration along joints in the oldest rocks and the mineralized veins and concentrations of trace metals in overlying lithologic units is direct evidence that copious volumes of mineralized and/or <span class="hlt">hydrothermal</span> fluids circulated through the early Martian crust. The wide range in intensity of structural and chemical modification from outcrop to outcrop along the crater rim shows that the ejecta of large (>8 km in diameter) impact craters is complex. These results imply that geologic complexity is to be anticipated in other areas of Mars where cratering has been a fundamental process in the local and regional geology and mineralogy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRE..120..538C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRE..120..538C"><span>Context of ancient aqueous environments on Mars from in situ geologic mapping at <span class="hlt">Endeavour</span> Crater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crumpler, L. S.; Arvidson, R. E.; Bell, J.; Clark, B. C.; Cohen, B. A.; Farrand, W. H.; Gellert, R.; Golombek, M.; Grant, J. A.; Guinness, E.; Herkenhoff, K. E.; Johnson, J. R.; Jolliff, B.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T.; Rice, J. W., Jr.; Squyres, S. W.; Sullivan, R.; Yen, A. S.</p> <p>2015-03-01</p> <p>Using the Mars Exploration Rover Opportunity, we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22 km diameter <span class="hlt">Endeavour</span> Crater (Latitude -2°16'33", Longitude -5°10'51"). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rocks distinguishes four mappable bedrock lithologic units. Three of these rock units predate the surrounding Burns formation sulfate-rich sandstones and one, the Matijevic Formation, represents conditions on early Mars predating the formation of <span class="hlt">Endeavour</span> Crater. The stratigraphy assembled from these observations includes several geologic unconformities. The differences in lithologic units across these unconformities record changes in the character and intensity of the Martian aqueous environment over geologic time. Water circulated through fractures in the oldest rocks over periods long enough that texturally and elementally significant alteration occurred in fracture walls. These oldest pre-<span class="hlt">Endeavour</span> rocks and their network of mineralized and altered fractures were preserved by burial beneath impact ejecta and were subsequently exhumed and exposed. The alteration along joints in the oldest rocks and the mineralized veins and concentrations of trace metals in overlying lithologic units is direct evidence that copious volumes of mineralized and/or <span class="hlt">hydrothermal</span> fluids circulated through the early Martian crust. The wide range in intensity of structural and chemical modification from outcrop to outcrop along the crater rim shows that the ejecta of large (>8 km in diameter) impact craters is complex. These results imply that geologic complexity is to be anticipated in other areas of Mars where cratering has been a fundamental process in the local and regional geology and mineralogy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8264T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8264T"><span>Interaction between <span class="hlt">hydrothermal</span> and magmatic <span class="hlt">systems</span>: modelling of magmatic gas release and ascent at Campi Flegrei (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Todesco, Micol; Afanasyev, Andrey; Montagna, Chiara Paola; Longo, Antonella</p> <p>2016-04-01</p> <p>We model the perturbation of a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> caused by the gas release from sub-surface magma chambers. First, we simulate the evolution of the magmatic <span class="hlt">system</span> composed by two magma reservoirs: a small and shallow chamber, filled with degassed phonolite, connected to a deeper reservoir of gas-rich shoshonite through a vertical dyke. The fluid-dynamics governing the replenishment of the upper chamber is computed with a 2D code solving conservation equations of mass, momentum and energy for a homogeneous multicomponent, multiphase Newtonian mixture, accounting for exsolution and dissolution of volatiles (H2O+CO2). We then assume that the volatiles that accumulate at the top of the upper chamber, escape from the reservoir and enter a steady state <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. The response of the <span class="hlt">hydrothermal</span> circulation is simulated with two multi-phase, multi-component porous media codes (MUFITS and TOUGH2) that describe the propagation of magmatic volatiles toward the surface. We create a simple model of Campi Flegrei <span class="hlt">hydrothermal</span> <span class="hlt">system</span> covering both shallow and deep regions where the temperature exceeds the critical temperature for water. Simulation results suggest that the rate at which volatiles are released from the magma chamber, the permeability distribution and the conditions of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> when degassing takes place can determine very different evolutions: accordingly, carbon dioxide may reach the surface within a time span ranging from weeks to millennia. The simulations indicate also that a single unrest event, associated with volatiles release from the chamber, can result in a periodic behaviour of observable parameters such as gas flux and fumarole composition. Duration of the period is of the order of 10 years, which is comparable with the time span between major unrest events observed at Campi Flegrei.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.B51B0399M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.B51B0399M"><span>Nitrogen cycling in Ophiolite-hosted and Fault-associated <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span>; Spacial and Temporal Variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer-Dombard, D. R.; Gulecal, Y.; Loiacono, S. T.; Cardace, D.; Uzunlar, N.; Temel, M.</p> <p>2011-12-01</p> <p>Gene-targeted analyses have revealed that microbial communities in <span class="hlt">hydrothermal</span> environments can be surprisingly diverse. However, we know shockingly little about basic ecological functions such as carbon and nitrogen cycling, or community shifts over time or with seasons. Previous work has shown that nitrogen cycling in a Yellowstone National Park hot spring, "Bison Pool", and its associated runoff channel functions as a complex <span class="hlt">system</span>. Analysis of nitrogen isotopes and sequencing of metagenomes from multiple locations at "Bison Pool" revealed that nitrogen fixation and denitrification varies across the chemosynthetic/photosynthetic ecotone [1-3], and high temperature activity of nifH genes has been shown for another nearby feature [4]. Other recent studies have explored the diversity of nifH and archaeal amoA genes in various terrestrial <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> [5-8]. Despite these advances, we are still ignorant of changes in N-cycling over time in the same sample location, and in particular during seasonal climate changes. Further, the role of N-cycling in deeply-sourced fluids associated with ophiolites, which represent deep biosphere processes, is unknown. This study will compare evidence of N-cycling in terrestrial <span class="hlt">hydrothermal</span> and ophiolite-hosted springs, focusing on the role of microbes as environmental conditions vary over space and time. Here, we explore the diversity of nifH [nitrogen fixation], amoA [ammonia oxidation], narG, nirKS, and nosZ [denitrification] genes in a variety of <span class="hlt">hydrothermal</span> environments in Yellowstone and Turkey, representing fault-associated and deeply-sourced fluids. Environmental nucleic acids were extracted, and PCR-directed screens reveal the presence or absence of functional genes, indicating genetic capacity for N-cycling. We have examined the transition of genetic diversity and genetic capacity within sediments and biofilms at the chemosynthetic/photosynthetic ecotone in several hot springs spanning ranges of pH and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1741&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1741&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- An ultrasound device is held at the site where the honeycomb shell around <span class="hlt">Endeavour</span>'s robotic arm has been cut to inspect the arm. A scrape of the shell occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1729&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1729&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- Workers in <span class="hlt">Endeavour</span>'s payload bay look at the site of the scrape on the surface of the honeycomb shell on the robotic arm that occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. The site will be cut out and ultrasound testing will be done on the structure underneath. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1728&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1728&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- The site being identified in the photo is the scrape on the surface of the honeycomb shell on <span class="hlt">Endeavour</span>'s robotic arm. The scrape occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. The site will be cut out and ultrasound testing will be done on the structure underneath. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1740&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1740&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- The opening shown here is the site where the honeycomb shell around <span class="hlt">Endeavour</span>'s robotic arm has been cut to inspect the arm. A scrape of the shell occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1730&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1730&hterms=robotic+arm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drobotic%2Barm"><span>Scrape on <span class="hlt">Endeavour</span>'s robotic arm during oxygen leak repairs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. -- One of a team of robotic experts looks at the site of the scrape on the surface of the the robotic arm's honeycomb shell. The scrape occurred while work platforms were being installed to gain access to repair the oxygen leak in <span class="hlt">Endeavour</span>'s mid-body. The site will be cut out and ultrasound testing will be done on the structure underneath. Launch of <span class="hlt">Endeavour</span> on mission STS-113 has been postponed until no earlier than Nov. 22.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010010950&hterms=music&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmusic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010010950&hterms=music&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmusic"><span>Rollout of <span class="hlt">Endeavour</span> at Palmdale, California (Part 1 of 2)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1991-01-01</p> <p>Footage shows the rollout ceremonies for <span class="hlt">Endeavour</span>, including the display of colors, invocation, and speeches by Sam Iacobellis, Executive Vice-President and CEO of Rockwell International, Richard H. Truly, Administrator for NASA, and Senator Jake Garn (Utah). The tape ends during the speech by Senator Garn and continues on part two (Input Processing ID 2000152220, Document ID 20010010951). <span class="hlt">Endeavour</span> rolls out to music provided by the band on-site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V13D..01G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V13D..01G"><span>Crustal magmatism under a <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, and the imprints of assimilation of <span class="hlt">hydrothermally</span> altered protolith: an investigation of geochemical signatures in rhyolitic magmas at Yellowstone caldera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Girard, G.</p> <p>2014-12-01</p> <p>Yellowstone caldera, Wyoming, hosts one of the largest <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on Earth, fueled by heat and volatiles released from hotspot-derived basalt magmas that stall in the crust. Prolonged <span class="hlt">hydrothermal</span> activity has pervasively altered the subsurface and such altered material is presumed to have acted as a source for magmas erupted after the two largest caldera eruptions, as evidenced by low-δ18O signatures in these magmas. This study focuses on the youngest Yellowstone volcanic units, the ~ 255 ka to ~ 70 ka large volume (~ 360 km3) Central Plateau Member (CPM) rhyolites. New laser-ablation ICP-MS whole rock, glass and mineral trace element data were obtained in order to refine existing constraints on CPM petrogenesis. Small temporal increases in elements such as As (3.1-4.1 ppm), Rb (170-200 ppm), Cs (3.6-4.3 ppm), Pb (26-31 ppm), Th (23-27 ppm) and U (5.4-6.8 ppm) contrast with increases of ~ 40-50 % in HFSE and REE in the same samples. The highest observed temporal increase is that of Zn, from 65 to 105 ppm. Caesium is highly incompatible with mineral/glass partition coefficients KD < 0.05 measured in all investigated mineral phases. Rubidium is also incompatible but its sanidine/glass KD ~ 0.4 results in a larger bulk distribution coefficient DRb ~ 0.2. For Pb, sanidine/glass KD ~ 0.8 leads to DPb > 0.4. Zinc is observed to be compatible in clinopyroxene, fayalite, zircon, chevkinite (KD ~ 5-12), and Fe-Ti oxides (KD ~ 40), such that DZn may approach 1. Fractional crystallization or partial melting processes alone cannot explain the same small increase rate of elements with diverse degrees of incompatibility (Rb, Cs and Pb), nor a larger increase rate in nearly compatible Zn. Assimilation by the juvenile CPM magmas of a crustal material of distinct composition appears to be required, and <span class="hlt">hydrothermally</span> altered rhyolites, comprising much of the Yellowstone subsurface represent the most likely assimilant. Lower Rb, Cs, Pb (perhaps also As and U) and higher</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3988086','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3988086"><span>Exopolysaccharides Isolated from <span class="hlt">Hydrothermal</span> Vent Bacteria Can Modulate the Complement <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Courtois, Anthony; Berthou, Christian; Guézennec, Jean</p> <p>2014-01-01</p> <p>The complement <span class="hlt">system</span> is involved in the defence against bacterial infection, or in the elimination of tumour cells. However, disturbances in this <span class="hlt">system</span> contributes to the pathogenesis of various inflammatory diseases. The efficiency of therapeutic anti-tumour antibodies is enhanced when the complement <span class="hlt">system</span> is stimulated. In contrast, cancer cells are able to inhibit the complement <span class="hlt">system</span> and thus proliferate. Some marine molecules are currently being developed as new drugs for use in humans. Among them, known exopolyssacharides (EPSs) generally originate from fungi, but few studies have been performed on bacterial EPSs and even fewer on EPSs extracted from deep-sea <span class="hlt">hydrothermal</span> vent microbes. For use in humans, these high molecular weight EPSs must be depolymerised. Furthermore, the over-sulphation of EPSs can modify their biological activity. The aim of this study was to investigate the immunodulation of the complement <span class="hlt">system</span> by either native or over-sulphated low molecular weight EPSs isolated from vent bacteria in order to find pro or anti-activators of complement. PMID:24736648</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS22A..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS22A..04S"><span>Experimental constraints on hydrogen generation in the <span class="hlt">hydrothermal</span> and fault <span class="hlt">systems</span> and their linkage to the eco-<span class="hlt">system</span> in ridge and subduction <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suzuki, K.; Shibuya, T.; Yoshizaki, M.; Masaki, Y.; Hirose, T.; Kawagucci, S.</p> <p>2012-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> vents were discovered in the late 1970s (Corliss et al., 1979; Edmond et al., 1979). Since then, they have been considered as a possible environment for the origin and early evolution of life on Earth (e.g., Yanagawa and Kojima, 1985; Russell and Hall, 1997). In addition, some researchers proposed that microbial ecosystems in the <span class="hlt">hydrothermal</span> vents are primary producers which sustain most of the lives in the ocean (Jannasch et al., 1985 and our TAIGA project [http://www-gbs.eps.s.u-tokyo.ac.jp/~taiga/en/index.html]). It is important, therefore, to figure out the <span class="hlt">hydrothermal</span> reactions in the ocean floor for better understanding of the ecosystems in the ocean. Especially interactions between oxidizing seawater and reducing agents such as hydrogen, hydrogen sulfide, methane and Fe (II) are one of the most crucial processes in the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. To constrain production of such reducing agents, we have established two types of the laboratory experimental <span class="hlt">systems</span>; the Dickson-type rock-<span class="hlt">hydrothermal</span> solution reaction <span class="hlt">system</span>, and the friction experiment <span class="hlt">system</span>. In this study, we focus on the hydrogen production in the reaction between ultramafic rocks and <span class="hlt">hydrothermal</span> solutions and in the fault <span class="hlt">systems</span> through the developed experimental <span class="hlt">systems</span>, which may reproduce in the laboratory the reactions occurring in the mid-ocean ridge and the subduction settings, respectively. The supply of abundant hydrogen to power primary producers in the ridge <span class="hlt">system</span> is the most likely coupled to <span class="hlt">hydrothermal</span> serpentinization of ultramafic rocks. Hydrogen-enriched <span class="hlt">hydrothermal</span> fluids are commonly associated with slow-spreading mid-ocean ridge (MOR) setting dominated by peridotite in the modern ocean (Kelley et al., 2001; Früh-Green et al., 2004). The serpentinization of abyssal peridotite has been well investigated both experimentally and theoretically. The investigations indicate that the peridotite-water reaction provides an extraordinarily high concentration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14582511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14582511"><span>A <span class="hlt">hydrothermal</span> <span class="hlt">system</span> associated with the Siljan impact structure, Sweden--implications for the search for fossil life on Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hode, Tomas; von Dalwigk, Ilka; Broman, Curt</p> <p>2003-01-01</p> <p>The Siljan ring structure (368 +/- 1.1 Ma) is the largest known impact structure in Europe. It isa 65-km-wide, eroded, complex impact structure, displaying several structural units, including a central uplifted region surrounded by a ring-shaped depression. Associated with the impact crater are traces of a post-impact <span class="hlt">hydrothermal</span> <span class="hlt">system</span> indicated by precipitated and altered <span class="hlt">hydrothermal</span> mineral assemblages. Precipitated <span class="hlt">hydrothermal</span> minerals include quartz veins and breccia fillings associated with granitic rocks at the outer margin of the central uplift, and calcite, fluorite, galena, and sphalerite veins associated with Paleozoic carbonate rocks located outside the central uplift. Two-phase water/gas and oil/gas inclusions in calcite and fluorite display homogenization temperatures between 75 degrees C and 137 degrees C. With an estimated erosional unloading of approximately 1 km, the formation temperatures were probably not more than 10-15 degrees C higher. Fluid inclusion ice-melting temperatures indicate a very low salt content, reducing the probability that the mineralization was precipitated during the Caledonian Orogeny. Our findings suggest that large impacts induce low-temperature <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> that may be habitats for thermophilic organisms. Large impact structures on Mars may therefore be suitable targets in the search for fossil thermophilic organisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AsBio...3..271H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AsBio...3..271H"><span>A <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> Associated with the Siljan Impact Structure, Sweden-Implications for the Search for Fossil Life 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>Hode, Tomas; von Dalwigk, Ilka; Broman, Curt</p> <p>2003-06-01</p> <p>The Siljan ring structure (368 +/- 1.1 Ma) is the largest known impact structure in Europe. It is a 65-km-wide, eroded, complex impact structure, displaying several structural units, including a central uplifted region surrounded by a ring-shaped depression. Associated with the impact crater are traces of a post-impact <span class="hlt">hydrothermal</span> <span class="hlt">system</span> indicated by precipitated and altered <span class="hlt">hydrothermal</span> mineral assemblages. Precipitated <span class="hlt">hydrothermal</span> minerals include quartz veins and breccia fillings associated with granitic rocks at the outer margin of the central uplift, and calcite, fluorite, galena, and sphalerite veins associated with Paleozoic carbonate rocks located outside the central uplift. Two-phase water/gas and oil/gas inclusions in calcite and fluorite display homogenization temperatures between 75°C and 137°C. With an estimated erosional unloading of ~1 km, the formation temperatures were probably not more than 10-15°C higher. Fluid inclusion ice-melting temperatures indicate a very low salt content, reducing the probability that the mineralization was precipitated during the Caledonian Orogeny. Our findings suggest that large impacts induce low-temperature <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> that may be habitats for thermophilic organisms. Large impact structures on Mars may therefore be suitable targets in the search for fossil thermophilic organisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V21A4739P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V21A4739P"><span>Indium: Understanding its Behavior in Magmatic-<span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> Today to Meet Tomorrow's Demand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piccoli, P. M.; Kayser, S.; Candela, P. A.</p> <p>2014-12-01</p> <p>Indium is integral to modern electronic devices, and is an essential component in indium-tin oxide (ITO), an electrically conductive, and optically transparent material that forms the basis for touch screens and high-end LCDs. World-wide production of indium has increased almost seven-fold from 1990 to 2012. Continued increases in production can be aided by better models for the formation of indium-bearing ores, yet little is known about the behavior of indium in magmatic-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. As a first step toward solving this problem, we performed experiments to evaluate the partitioning of indium between pyrrhotite (po) and silicate melt (m). Experiments were performed at 800 °C, 100 MPa, and fO2 ≈ NNO in a po-saturated, vapor-brine-rhyolite melt <span class="hlt">system</span> for durations of 5 to15 days. Three separate series of experiments were conducted in which each series differed by the aqueous solution added. The first series of experiments were prepared with pure water, the second series of experiments with a 1.01 M chloride solution and the third series with a 0.35 M CuCl2-bearing starting aqueous solution. These changes in starting material produced changes in the composition of the run product po and glass. The partition coefficient D(po/m) for the pure-water series experiments is on the order of ≈ 10. The addition of chloride-bearing aqueous solution leads to a decrease in the partition coefficient to ≈ 1.5. The copper-bearing experiments yield a D ≈ 3. The lower values for D in the chloride-bearing experiments may be explained by indium-chloride interactions in the melt phase. Although the D does vary depending upon the composition of the starting aqueous solution, an order of magnitude estimate for D, for general modeling purposes, can be made by assuming a value of 4. By using reasonable estimates of the mass fraction of po that crystallizes in crustal magmatic <span class="hlt">systems</span>, the proportion of indium sequestered by po, during fractional crystallization, can be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5109689','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5109689"><span>Comparative assessment of five potential sites for <span class="hlt">hydrothermal</span> magma <span class="hlt">systems</span>: geochemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>White, A.F.</p> <p>1980-08-01</p> <p>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 <span class="hlt">hydrothermal</span> sites are categorized into three groups for presentation: geochemistry of magma and associated volcanic rocks, geochemistry of <span class="hlt">hydrothermal</span> solutions, and geochemistry of <span class="hlt">hydrothermal</span> alteration. (MHR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26375668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26375668"><span>Microbial diversity in deep-sea sediments from the Menez Gwen <span class="hlt">hydrothermal</span> vent <span class="hlt">system</span> of the Mid-Atlantic Ridge.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cerqueira, Teresa; Pinho, Diogo; Egas, Conceição; Froufe, Hugo; Altermark, Bjørn; Candeias, Carla; Santos, Ricardo S; Bettencourt, Raul</p> <p>2015-12-01</p> <p>Deep-sea <span class="hlt">hydrothermal</span> sediments are known to support remarkably diverse microbial consortia. Cultureindependent sequence-based technologies have extensively been used to disclose the associated microbial diversity as most of the microorganisms inhabiting these ecosystems remain uncultured. Here we provide the first description of the microbial community diversity found on sediments from Menez Gwen vent <span class="hlt">system</span>. 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 site-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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15213826','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15213826"><span>Development of an in situ fiber optic Raman <span class="hlt">system</span> to monitor <span class="hlt">hydrothermal</span> vents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Battaglia, Tina M; Dunn, Eileen E; Lilley, Marvin D; Holloway, John; Dable, Brian K; Marquardt, Brian J; Booksh, Karl S</p> <p>2004-07-01</p> <p>The development of a field portable fiber optic Raman <span class="hlt">system</span> modified from commercially available components that can operate remotely on battery power and withstand the corrosive environment of the <span class="hlt">hydrothermal</span> vents is discussed. The Raman <span class="hlt">system</span> is designed for continuous monitoring in the deep-sea environment. A 785 nm diode laser was used in conjunction with a sapphire ball fiber optic Raman probe, single board computer, and a CCD detector. Using the <span class="hlt">system</span> at ambient conditions the detection limits of SO(4)(2-), CO(3)(2-) and NO(3)(-) were determined to be approximately 0.11, 0.36 and 0.12 g l(-1) respectively. Mimicking the cold conditions of the sea floor by placing the equipment in a refrigerator yielded slightly worse detection limits of approximately 0.16 g l(-1) for SO(4)(-2) and 0.20 g l(-1) for NO(3)(-). Addition of minerals commonly found in vent fluid plumes also decreased the detection limits to approximately 0.33 and 0.34 g l(-1) respectively for SO(4)(-2) and NO(3)(-).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7525J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7525J"><span>A seismic network to investigate the sedimentary hosted <span class="hlt">hydrothermal</span> Lusi <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Javad Fallahi, Mohammad; Mazzini, Adriano; Lupi, Matteo; Obermann, Anne; Karyono, Karyono</p> <p>2016-04-01</p> <p>The 29th of May 2006 marked the beginning of the sedimentary hosted <span class="hlt">hydrothermal</span> Lusi <span class="hlt">system</span>. During the last 10 years we witnessed numerous alterations of the Lusi <span class="hlt">system</span> behavior that coincide with the frequent seismic and volcanic activity occurring in the region. In order to monitor the effect that the seismicity and the activity of the volcanic arc have on Lusi, we deployed a ad hoc seismic network. This temporary network consist of 10 broadband and 21 short period stations and is currently operating around the Arjuno-Welirang volcanic complex, along the Watukosek fault <span class="hlt">system</span> and around Lusi, in the East Java basin since January 2015. We exploit this dataset to investigate surface wave and shear wave velocity structure of the upper-crust beneath the Arjuno-Welirang-Lusi complex in the framework of the Lusi Lab project (ERC grant n° 308126). Rayleigh and Love waves travelling between each station-pair are extracted by cross-correlating long time series of ambient noise data recorded at the stations. Group and phase velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions, and are tomographically inverted to provide 2D velocity maps corresponding to different sampling depths. 3D shear wave velocity structure is then acquired by inverting the group velocity maps.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..276..132G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..276..132G"><span>Asymmetrical structure, <span class="hlt">hydrothermal</span> <span class="hlt">system</span> and edifice stability: The case of Ubinas volcano, Peru, revealed by geophysical surveys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzales, Katherine; Finizola, Anthony; Lénat, Jean-François; Macedo, Orlando; Ramos, Domingo; Thouret, Jean-Claude; Fournier, Nicolas; Cruz, Vicentina; Pistre, Karine</p> <p>2014-04-01</p> <p>Ubinas volcano, the historically most active volcano in Peru straddles a low-relief high plateau and the flank of a steep valley. A multidisciplinary geophysical study has been performed to investigate the internal structure and the fluids flow within the edifice. We conducted 10 self-potential (SP) radial (from summit to base) profiles, 15 audio magnetotelluric (AMT) soundings on the west flank and a detailed survey of SP and soil temperature measurements on the summit caldera floor. The typical “V” shape of the SP radial profiles has been interpreted as the result of a <span class="hlt">hydrothermal</span> zone superimposed on a hydrogeological zone in the upper parts of the edifice, and depicts a sub-circular SP positive anomaly, about 6 km in diameter. The latter is centred on the summit, and is characterised by a larger extension on the western flank located on the low-relief high plateau. The AMT resistivity model shows the presence of a conductive body beneath the summit at a depth comparable to that of the bottom of the inner south crater in the present-day caldera, where intense <span class="hlt">hydrothermal</span> manifestations occur. The lack of SP and temperature anomalies on the present caldera floor suggests a self-sealed <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, where the inner south crater acts as a pressure release valve. Although no resistivity data exists on the eastern flank, we presume, based on the asymmetry of the basement topography, and the amplitude of SP anomalies on the east flank, which are approximately five fold that on the west flank, that gravitational flow of <span class="hlt">hydrothermal</span> fluids may occur towards the deep valley of Ubinas. This hypothesis, supported by the presence of hot springs and faults on the eastern foot of the edifice, reinforces the idea that a large part of the southeast flank of the Ubinas volcano may be altered by <span class="hlt">hydrothermal</span> activity and will tend to be less stable. One of the major findings that stems from this study is that the slope of the basement on which a volcano has grown</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985imzf.rept.....W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985imzf.rept.....W"><span>Indications of mineral zoning in a fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Meager Creek geothermal prospect, British Columbia, Canada from induced polarization studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ward, S. H.; Zhao, J. X.; Groenwald, J.; Moore, J. N.</p> <p>1985-05-01</p> <p>By measuring the induced polarization parameters m (chargeability) and tau (time constant) evidence was found that the center of a presumed fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at Meager Creek, British Columbia, lies south of the main manifestation of the present day convective <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. What implication this finding has for development of the present day <span class="hlt">system</span> is unknown. However, some of the fractures formed during the development of the fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> may serve as conduits for fluids of the present day <span class="hlt">system</span>. The analysis is limited by the lack of availability of a good subsurface distribution of core samples. Nevertheless, a surface induced polarization survey is expected to yield information about the geometry of the fossil <span class="hlt">system</span>. Such knowledge would have implications not only for Meager Creek but for other <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of Cascades volcano type.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5684430','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5684430"><span>Indications of mineral zoning in a fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Meager Creek geothermal prospect, British Columbia, Canada, from induced polarization studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ward, S.H.; Zhao, J.X.; Groenwald, J.; Moore, J.N.</p> <p>1985-05-01</p> <p>By measuring the induced-polarization parameters m (chargeability) and tau (time-constant) we have found evidence that the center of a presumed fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at Meager Creek, British Columbia, lies south of the main manifestation of the present-day convective <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. What implication this finding has for development of the present-day <span class="hlt">system</span> is unknown. However, some of the fractures formed during the development of the fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> may serve as conduits for fluids of the present-day <span class="hlt">system</span>. The analysis is limited by the lack of availability of a good subsurface distribution of core samples. Nevertheless, a surface induced-polarization survey is expected to yield information about the geometry of the fossil <span class="hlt">system</span>. Such knowledge would have implications not only for Meager Creek but for other <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> of Cascades volcano type. 16 refs., 15 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JIEIB..96..273P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JIEIB..96..273P"><span>Neuro-Fuzzy Computational Technique to Control Load Frequency in <span class="hlt">Hydro-Thermal</span> Interconnected Power <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prakash, S.; Sinha, S. K.</p> <p>2015-09-01</p> <p>In this research work, two areas <span class="hlt">hydro-thermal</span> power <span class="hlt">system</span> connected through tie-lines is considered. The perturbation of frequencies at the areas and resulting tie line power flows arise due to unpredictable load variations that cause mismatch between the generated and demanded powers. Due to rising and falling power demand, the real and reactive power balance is harmed; hence frequency and voltage get deviated from nominal value. This necessitates designing of an accurate and fast controller to maintain the <span class="hlt">system</span> parameters at nominal value. The main purpose of <span class="hlt">system</span> generation control is to balance the <span class="hlt">system</span> generation against the load and losses so that the desired frequency and power interchange between neighboring <span class="hlt">systems</span> are maintained. The intelligent controllers like fuzzy logic, artificial neural network (ANN) and hybrid fuzzy neural network approaches are used for automatic generation control for the two area interconnected power <span class="hlt">systems</span>. Area 1 consists of thermal reheat power plant whereas area 2 consists of hydro power plant with electric governor. Performance evaluation is carried out by using intelligent (ANFIS, ANN and fuzzy) control and conventional PI and PID control approaches. To enhance the performance of controller sliding surface i.e. variable structure control is included. The model of interconnected power <span class="hlt">system</span> has been developed with all five types of said controllers and simulated using MATLAB/SIMULINK package. The performance of the intelligent controllers has been compared with the conventional PI and PID controllers for the interconnected power <span class="hlt">system</span>. A comparison of ANFIS, ANN, Fuzzy and PI, PID based approaches shows the superiority of proposed ANFIS over ANN, fuzzy and PI, PID. Thus the hybrid fuzzy neural network controller has better dynamic response i.e., quick in operation, reduced error magnitude and minimized frequency transients.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IJEaS.tmp....9C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IJEaS.tmp....9C"><span>Fluid geochemistry of the Mondragone <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> (southern Italy): water and gas compositions vs. geostructural setting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuoco, Emilio; Minissale, Angelo; Di Leo, Antonella "Magda"; Tamburrino, Stella; Iorio, Marina; Tedesco, Dario</p> <p>2017-02-01</p> <p>The geochemistry of natural thermal fluids discharging in the Mondragone Plain has been investigated. Thermal spring emergences are located along the Tyrrhenian coast in two different areas: near Padule-S. Rocco (41°7.5'N 13°53.4'E) at the foot of Mt. Petrino, and near Levagnole (41°8.5'N 13°51.3'E) at the foot of Mt. Pizzuto. The water isotopic composition of both thermal discharges is lighter than the one of local shallow groundwater (δ18O ≅ -6.3‰ SMOW vs. ≅ -5.9‰; δD ≅ -40‰ SMOW vs. ≅ -36‰, respectively) as a consequence of inland higher altitude of recharge by rainfall, suggesting that thermal water undergoes a deep and long flow-path before emerging along the coast. The chemical composition of the highest temperature samples of two areas points that fluids in the <span class="hlt">hydrothermal</span> reservoir(s) interact with similar lithologies, since they are both hosted in the lower sedimentary carbonate formations of the Campanian-Latial Apennine succession. However, the two spring <span class="hlt">systems</span> are different in terms of temperature and salinity (Levagnole: ≅50 °C and 8.9 g/L vs. Padule: ≅32 °C and 7.4 g/L, respectively). The higher salinity of Levagnole springs is due to a longer interaction with evaporite material embedded in Miocene sedimentary formations and to the eventual mixing, during rising, with fresh seawater close to the seashore. The chemical and isotopic composition of the free gases associated with the springs, again suggests a different source of the two <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Comparing the 3He/4He measured ratios with other gas emissions located NE and SE of Mt. Massico-Roccamonfina alignment, it is evident that the Levagnole thermal springs are related to the northern Latial mantle wedge where the 3He/4He is about 0.5 R/Ra, whereas the Padule-S. Rocco springs, although being only 3.5 km south of Levagnole, are related to the Campanian mantle wedge where R/Ra is always ≥2.0. Such a difference in 3He/4He ratio in a very short distance</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050177167','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050177167"><span>Smoldering News From STS-77 <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koudelka, John M.; Fernandez-Pello, A. Carlos</p> <p>1997-01-01</p> <p>The Microgravity Smoldering Combustion (MSC) experiment lifted off aboard the Space Shuttle <span class="hlt">Endeavour</span> for its second flight in May 1996, as part of the STS-77 mission. This experiment is part of a series of studies focused on the smolder characteristics of porous combustible materials in a microgravity environment. Smoldering is a nonflaming form of combustion that takes place in the interior of combustible materials. Common examples of smoldering are nonflaming embers, charcoal briquettes, and cigarettes. The objective of this study is to provide a better understanding of the controlling mechanisms of smoldering in microgravity and normal Earth gravity (1g). As with other forms of combustion, gravity affects the availability of air and transport of heat, and therefore, the rate of combustion. The results of the microgravity experiments will be compared with identical ones carried out in 1g. In addition, they will be used to verify present theories of smolder combustion and will provide new insights into the process of smoldering combustion, enhancing our fundamental understanding of this frequently encountered combustion process and guiding improvements in fire safety practices. Two smoldering combustion tests with polyurethane foam were successfully accomplished during the STS-77 mission. The tests investigated smoldering combustion in a quiescent (no-flow) enriched oxygen environment, and in an air environment with a 2-mm/sec airflow through the fuel sample. The primary data from the tests are the ignition characteristics, spread rate, smolder reaction temperature, and products of combustion (solid and gas). On both the first mission on STS-69 and the second mission on STS-77, a smolder front propagated the length of the forced-flow samples, with the spread rate between the corresponding upward and downward 1g smolder rates. Neither of the quiescent cases propagated combustion (the first case was due in part to a problem with the experiment electronics). These</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V21D..01Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V21D..01Y"><span>An alternative modeling framework for better interpretation of the observed volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yue, Z. Q. Q.</p> <p>2015-12-01</p> <p>Many phenomena and data related to volcanoes and volcano eruptions have been observed and collected over the past four hundred years. They have been interpreted with the conventional and widely accepted hypothesis or theory of hot magma fluid from mantle. However, the prediction of volcano eruption sometimes is incorrect. For example, the devastating eruption of the Mount Ontake on Sept. 27, 2014 was not predicted and/or warned at all, which caused 55 fatalities, 9 missing and more than 60 injured. Therefore, there is a need to reconsider the cause and mechanism of active volcano and its <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. On the basis of more than 30 year study and research in geology, volcano, earthquake, geomechanics, geophysics, geochemistry and geohazards, the author has developed a new and alternative modeling framework (or hypothesis) to better interpret the observed volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> data and to more accurately predict the occurrence of volcano explosion. An active volcano forms a cone-shape mountain and has a crater with vertical pipe conduit to allow hot lava, volcanic ash and gases to escape or erupt from its chamber (Figure). The chamber locates several kilometers below the ground rocks. The active volcanos are caused by highly compressed and dense gases escaped from the Mantle of the Earth. The gases are mainly CH4 and further trapped in the upper crustal rock mass. They make chemical reactions with the surrounding rocks in the chamber. The chemical reactions are the types of reduction and decomposition. The reactions change the gas chemical compounds into steam water gas H2O, CO2, H2S, SO2 and others. The oxygen in the chemical reaction comes from the surrounding rocks. So, the product lava has a less amount of oxygen than that of the surrounding rocks. The gas-rock chemical reactions produce heat. The gas expansion and penetration power and the heat further break and crack the surrounding rock mass and make them into lavas, fragments, ashes or bombs. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B11B1028A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B11B1028A"><span>Archaeal Communities in an Arsenic-Rich Shallow-Sea <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akerman, N. H.; Meyer-Dombard, D. R.; Osburn, M. R.; Amend, J. P.</p> <p>2006-12-01</p> <p>Arsenic is toxic to many life forms, but a number of microbes can tolerate and even metabolize it. Numerous Bacteria, particularly among the Proteobacteria, can gain energy from arsenate (AsV) reduction or arsenite (AsIII) oxidation. With few exceptions (Pyrobaculum arsenaticum and P. aerophilum), Archaea are not known to metabolize arsenic. The shallow-sea <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in Tutum Bay, Ambitle Island, Papua New Guinea provides an ideal setting to investigate the presence, phylogenetic diversity, and biogeochemical role of Archaea in arsenic-rich environments. The <span class="hlt">hydrothermal</span> fluids in Tutum Bay are characterized by highly elevated AsIII concentrations (up to 950 μg/L); the rocks and coral near vent orifices are coated with 2-line ferrihydrite and co-precipitated AsV (up to 7 wt%). With increasing distance from the vent, the arsenic concentrations analyzed in porewater samples decrease exponentially to ~6 μg/L at 300m. Archaeal 16S rRNA gene surveys of DNA extracted from the vent fluids, rock coatings, and sediment samples along the transect revealed only one Crenarchaeotal sequence in the vent fluid, but rich archaeal communities in the biofilm coating the rocks and in the sediments. Both these communities consist predominantly of uncultured Crenarchaeota, but the sediment communities also include members of the Euryarchaeota and the Korarchaeota. Detailed chemical analyses were combined with standard Gibbs energies to compute the potential energy yields of numerous redox reactions at in situ temperatures. These calculations showed that AsV reduction reactions using sulfide and ferrous iron as electron donors were exergonic (yielding 4 to 24 kJ/mol e-). AsIII oxidation reactions, using oxygen, nitrate, and nitrite as terminal electron acceptors, yielded significantly more energy (27 to 84 kJ/mol e-). Such calculations show that abundant energy exists in this <span class="hlt">system</span> for microorganisms that can metabolize arsenic, and they suggest that microbes involved in As</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PApGe.174.1471B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PApGe.174.1471B"><span>Structural Architecture of the <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> from Geophysical Data in Hammam Bouhadjar Area (Northwest of Algeria)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouyahiaoui, Boualem; Abtout, Abdeslam; Hamai, Lamine; Boukerbout, Hassina; Djellit, Hamou; Bougchiche, Said Sofiane; Bendali, Mohamed; Bouabdallah, Hamza</p> <p>2017-03-01</p> <p>We determine the structural architecture of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Hammam Bouhadjar area (Northwest of Algeria) by the use of geophysical data. New gravity and electrical surveys covered an area of about 48 km2 in 2009. There were 350 gravity measurements made with a sampling of 500 m and 45 electrical soundings (Schlumberger type, AB = 1000 m). The Bouguer anomaly map shows a regression of gravity field towards the NW and SE. All of the observed anomalies are elongated in NE-SW direction. The results obtained from different processing methods (gradients, upward continuation, Euler deconvolution, wavelet transform and modelling) of gravity data were used to generate structural map of the studied area. The vertical and horizontal variations of resistivity confirm the presence of superficial and deeper faults <span class="hlt">system</span>. Following the geophysical (gravity and electrical) analysis and modelling, we propose a model to explain the origin of the Hammam Bouhadjar thermal waters. We suggest that the hot spring water comes from an aquifer located in sandstones lenses in the Senono-Oligocene Tellian unit. Following the gravity modelling the aquifer is identified at about 800 m, the same depth where the geothermal gradient is insufficient to heat the water. In these circumstances, the aquifer is probably heated by volcanic processes connected with a hot compartment by faults and contacts affecting structures identified in depth. The presence of a conductor along of the horseshoe area suggests that the water percolates into this area and then is drained by the different accidents to invade the whole area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.B51G0492L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.B51G0492L"><span>In situ Expression of Functional Genes Reveals Nitrogen Cycling at High Temperatures in Terrestrial <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loiacono, S. T.; Meyer-Dombard, D. R.</p> <p>2011-12-01</p> <p> using (reverse-transcription) polymerase chain reaction to identify the presence and expression of nifH genes, and resultant (RT-)PCR product was cloned and sequenced. Results reveal high-temperature in situ expression of nifH in select LGB features [7] which is, to the authors' knowledge, the first direct evidence of nifH transcription in the chemosynthetic zones of terrestrial <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Results also indicate the presence of novel nifH sequences and allow phylogenetic comparison of nifH genes along geochemical gradients within individual hot spring features and between various thermal features in the LGB. Collectively, these results provide evidence for microbial adaptations that have led to the ability to support basic metabolic processes under "extreme" conditions. [1] Hall et al., 2008. AEM 74: 4910-4922. [2] Steunou et al., 2008. The ISME Journal 2: 364-378. [3] Hamilton et al., 2011. Microb Ecol DOI 10.1007/s00248-011-9824-9. [4] Raymond et al., 2008. EOS Trans AGU. Abstract B14A-03. [5] Havig et al., 2010. J Geophys Res-Biogeo 116: G01005. [6] Mehta & Baross, 2006. Science 314: 1783-1786. [7] Loiacono et al., 2011. Submitted FEMS Microbiol Ecol.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9016D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9016D"><span>Did a whole-crustal <span class="hlt">hydrothermal</span> <span class="hlt">system</span> generate the Irish Zn-Pb orefield?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daly, J. Stephen; Badenszki, Eszter; Chew, David; Kronz, Andreas; O'Rourke, Helen; Whitehouse, Martin; Menuge, Julian; van den Berg, Riana</p> <p>2016-04-01</p> <p>Current models[1] for the genesis of the giant Irish Carboniferous-hosted Zn-Pb orefield propose shallow (<10 km depth) <span class="hlt">hydrothermal</span> circulation within Lower Palaeozoic basement rocks of the Iapetus Suture Zone as the main metal source. However several lines of evidence, e.g., from He[2], S[2,3] and Os[4] isotopes, and the possible role of contemporary volcanism[5] point to deeper, including mantle, fluid source(s) and/or pathways. The Iapetus Suture Zone in Ireland is uniquely favoured to evaluate the scale of <span class="hlt">hydrothermal</span> circulation because of the presence there of granulite-facies lower crustal xenoliths at four widely separated localities. These were carried to the surface from ~22-28km (and deeper levels) by Lower Carboniferous alkali basaltic lavas and diatremes[6,7]. They provide the only possible direct samples of the lower crust and are of appropriate age. U-Pb zircon geochronology demonstrates that the xenoliths experienced high temperature (>700°C) metamorphism and melting during the Acadian orogeny at ~390Ma and during separate episodes of extension at ~ 381-373Ma and ~362Ma. Sm-Nd garnet dating shows that the lower crust remained hot or was re-heated to ~600°C at ~341Ma during Lower Carboniferous volcanism, also associated with extension and, in part, coincident with the mineralization[1]. Isotopic data from the xenoliths correspond closely to Sr and Nd isotopic analyses of gangue calcite[8] and galena Pb[9] isotopic data from the major ore deposits. While Zn contents of the xenoliths permit them to be metal sources, their mineralogy and texture provide an enriched template and a plausible extraction mechanism. In situ analyses of modally-abundant biotite and garnet show significant enrichment in Zn (and other relevant metals) as well as order of magnitude depletion of Zn during retrograde alteration, providing a metal-release mechanism and pointing to a <span class="hlt">hydrothermal</span> fluid <span class="hlt">system</span> operating at least to depths of ~ 25km. References [1] Wilkinson, J</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeCoA..70.6180R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeCoA..70.6180R"><span>Energetics of potential heterotrophic metabolisms in the marine <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Vulcano Island, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rogers, Karyn L.; Amend, Jan P.</p> <p>2006-12-01</p> <p>Values of overall Gibbs free energy of 144 organic oxidation (respiration) and disproportionation (fermentation) reactions are calculated at the temperatures and chemical compositions that exist in nine submarine vents, sediment seeps and geothermal wells in the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Vulcano Island, Italy. The organic compounds considered here include four carboxylic acids (formic, acetic, propanoic and lactic), two C 5 aldoses (arabinose and xylose), three C 6 aldoses (galactose, glucose and mannose), and 15 protein-forming amino acids (Ala, Arg, Asp, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Ser, Thr, Tyr, and Val). Oxidation of these compounds is coupled to five redox pairs: O 2/H 2O, SO42-/HS, S 0/H 2S, NO3-/NH4+ and Fe 3O 4/Fe 2+. Energy yields from potential respiration reactions range from 6 to 118 kJ/mol of electrons transferred and show systematic behavior with respect to the terminal electron acceptor. Overall, respiration with O 2 yields the most energy (98-118 kJ/mol e -), followed by reactions with NO3- (53- 86 kJ/mol e -), magnetite (29-91 kJ/mol e -), S 0 (11-33 kJ/mol e -) and SO42- (6-34 kJ/mol e -). Energy yields show little correlation with organic compound family, but are correlated with fluid pH. Variability in energy yields across the nine sites is greatest for Fe(III) reduction and is primarily influenced by pH and the activity of Fe 2+. In addition to the potential respiration reactions, the energetics of 24 potential fermentation reactions are also calculated. As expected, fermentation reactions generally yield much less energy than respiration. Normalized to the number of moles of carbon transferred, fermentation yields-8 to 71 kJ/mol C, compared with 16 to 531 kJ/mol C for respiration reactions. All respiration and fermentation reactions, except for methionine (Met) fermentation, are exergonic under the in situ <span class="hlt">hydrothermal</span> conditions and represent a plethora of potential metabolisms for Vulcano's diverse thermophilic heterotrophs.</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('https://ntrs.nasa.gov/search.jsp?R=20040088936&hterms=Hydrothermal+vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHydrothermal%2Bvents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088936&hterms=Hydrothermal+vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHydrothermal%2Bvents"><span>A Mossbauer investigation of iron-rich terrestrial <span class="hlt">hydrothermal</span> vent <span class="hlt">systems</span>: lessons for Mars exploration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wade, M. L.; Agresti, D. G.; Wdowiak, T. J.; Armendarez, L. P.; Farmer, J. D.</p> <p>1999-01-01</p> <p><span class="hlt">Hydrothermal</span> spring <span class="hlt">systems</span> may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a Mossbauer spectrometer. In the context of future Mars exploration we present results of Mossbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that Mossbauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (alpha-Fe2O3), small-particle/nanophase goethite (alpha-FeOOH), and siderite (FeCO3). We find for iron minerals that Mossbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, Mossbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multi-billion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the Mossbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11542933','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11542933"><span>A Mossbauer investigation of iron-rich terrestrial <span class="hlt">hydrothermal</span> vent <span class="hlt">systems</span>: lessons for Mars exploration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wade, M L; Agresti, D G; Wdowiak, T J; Armendarez, L P; Farmer, J D</p> <p>1999-04-25</p> <p><span class="hlt">Hydrothermal</span> spring <span class="hlt">systems</span> may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a Mossbauer spectrometer. In the context of future Mars exploration we present results of Mossbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that Mossbauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (alpha-Fe2O3), small-particle/nanophase goethite (alpha-FeOOH), and siderite (FeCO3). We find for iron minerals that Mossbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, Mossbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multi-billion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the Mossbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43..168H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43..168H"><span>Depressurization of a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> following the August and November 2012 Te Maari eruptions of Tongariro, 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>Hamling, I. J.; Williams, C. A.; Hreinsdóttir, S.</p> <p>2016-01-01</p> <p>In 2012, two phreatic eruptions occurred at New Zealand's Tongariro volcano for the first time in over a century. Interferometric Synthetic Aperture Radar data collected by the Italian Space Agency's COSMO-SkyMed satellite constellation, indicates up to 20 mm/yr of post eruptive subsidence focused across a 4 km2 region in the vicinity of the eruption site. Modeling of the deformation data indicates a shallow source at ˜500 m depth (1100 m asl) consistent with the depth of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. We estimate an annual volume loss of 35,000 m3, leading to a pressure loss of ˜0.09 MPa/yr. We suggest that fracturing associated with the eruptions has enabled the continued depressurization of the shallow <span class="hlt">hydrothermal</span> <span class="hlt">system</span> and that subsidence will continue until the fractures become resealed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1975/of75-525/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1975/of75-525/"><span>Physical factors determining the fraction of stored energy recoverable from <span class="hlt">hydrothermal</span> convection <span class="hlt">systems</span> and conduction-dominated areas</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nathenson, Manuel</p> <p>1975-01-01</p> <p>This report contains background analyses for the estimates of Nathenson and Muffler (1975) of geothermal resources in <span class="hlt">hydrothermal</span> convection <span class="hlt">systems</span> and conduction-dominated areas. The first section discusses heat and fluid recharge potential of geothermal reservoirs. The second section analyzes the physical factors that determine the fraction of stored energy obtainable at the surface from a geothermal reservoir. Conversion of heat to electricity and the use of geothermal energy for direct-heating applications are discussed in the last two sections. Nathenson, Manuel, and Muffler, L.J.P., 1975, Geothermal resources in <span class="hlt">hydrothermal</span> convection <span class="hlt">systems</span> and conduction dominated areas, in White, D.E., and Williams, D.L., eds., Assessment of the Geothermal Resources of the United States--1975: U.S. Geological Survey Circular 726, p. 104-121, available at http://pubs.er.usgs.gov/usgspubs/cir/cir726</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100039623&hterms=history+water+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dhistory%2Bwater%2Bearth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100039623&hterms=history+water+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dhistory%2Bwater%2Bearth"><span>Evaluating the Historical Importance of Impact Induced <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> on Mars Using the Stable Isotopic Composition of Martian Water</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Niles, Paul B.</p> <p>2010-01-01</p> <p>The importance of impact events during the early history of Mars is obvious through a simple examination of the character of the martian surface. This ancient, heavily cratered terrain has been shown to be associated with extensive phyllosilicate deposits. This geologic link could suggest that the extensive phyllosilicate-forming alteration may have occurred during early martian history through impact-induced <span class="hlt">hydrothermal</span> alteration. However, examination of the oxygen isotopic composition of water on Mars suggests that the extensive phyllosilicate deposits were formed primarily through low temperature (<30 C) interactions, and that high temperature weathering in impact-induced <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> have not been a dominant process on Mars. The average oxygen isotopic composition of water on Earth is dictated by the nature of water-rock interactions. If these interactions occur at higher temperatures then the water will contain a higher proportion of 18O, while lower temperature interactions will result in water with a lower proportion of 18O. Water on Earth today contains a higher proportion of 18O because of plate tectonics and <span class="hlt">hydrothermal</span> interaction at mid-ocean ridges. The oxygen isotopic composition of water on early earth, however, may have been quite different, containing a smaller proportion of 18O suggesting much less <span class="hlt">hydrothermal</span> interaction. Because there are not yet any direct measurements of the oxygen isotopic composition of water on Mars, it needs to be inferred through examination of carbonates preserved in martian meteorites and the isotopic composition of atmospheric CO2. This can be done because the oxygen incorporated into carbonates and CO2 is easily exchanged with liquid water if it is present. Independently, both measurements provide an estimate for the (Sigma)18O of water on Mars to be near -16%. This composition is consistent with low temperature weathering of the silicate crust, and indicates that impact <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> did not play</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5426350','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5426350"><span>Application of fluid dynamics principles in tilted permeable media to terrestrial <span class="hlt">hydrothermal</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Criss, R.E.; Hofmeister, A.M.</p> <p>1991-02-01</p> <p>Fluid dynamics principles require that circulation of aqueous fluid will be practically ubiquitous in tectonically active parts of the Earth's crust and upper mantle. Both experiment and theory demonstrate that flow, generally in the form of unicells (Hadley circulation), always occurs for isothermal tilts above a very small critical angle ({approximately}5{degree}), for any non-zero permeability or Rayleigh number, and even for hot over cold geometries. Interestingly, heat transport rates in the unicellular regime are essentially conductive, so such flow, unlike more vigorous flow at higher Rayleigh number, is not properly termed convective. These principles have numerous geological ramifications, including: (1) many of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> developed around epizonal intrusions should be dominantly unicellular in nature, which explains their aspect ratios and the smooth and very regular {delta}{sup 18}O variations that are produced in the rocks; (2) large, long-lived unicells are predicted to occur deep in the Earth's crust wherever Rayleigh numbers are finite and isotherms are substantially inclined, as in zones of batholith intrusion, regional metamorphism, and collision; (3) unicells with lateral dimensions of several hundred kilometers are predicted to be associated with subduction zones dipping more than 6-12{degree}, with fluid advection into the hot mantle wedge being instrumental in mantle metasomatism and in the generation of andesitic magmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/136213','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/136213"><span>Mapping the fluid flow of the Mariana Mounds ridge flank <span class="hlt">hydrothermal</span> <span class="hlt">system</span>: Pore water chemical tracers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wheat, C.G.; McDuff, R.E.</p> <p>1995-05-10</p> <p>The authors present a conceptual model of fluid circulation in a ridge flank <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, the Mariana Mounds. The model is based on chemical data from pore waters extracted from piston cores and from push cores collected by deep-sea research vessel Alvin in small, meter-sized mounds situated on a local topographic high. These mounds are located within a region of heat flow exceeding that calculated from a conductive model and are zones of strong pore water upflow. The authors have interpreted the chemical data with time-dependent transport-reaction models to estimate pore water velocities. In the mounds themselves pore water velocities reach several meters per year to kilometers per year. Within about 100 m from these zones of focused upflow velocities decrease to several centimeters per year up to tens of centimeters per year. A large area of low heat flow surrounds these heat flow and topographic highs, with upwelling pore water velocities less than 2 cm/yr. In some nearby cores, downwelling of bottom seawater is evident but at speeds less than 2 cm/yr. Downwelling through the sediments appears to be a minor source of seawater recharge to the basaltic basement. The authors conclude that the principal source of seawater recharge to basement is where basement outcrops exist, most likely a scarpt about 2-4 km to the east and southeast of the study area. 71 refs., 14 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-0227&hterms=rainbow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Drainbow','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-0227&hterms=rainbow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Drainbow"><span>STS-99 <span class="hlt">Endeavour</span> lifts off from Launch Pad 39A</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>A rainbow corona of light shimmers behind Space Shuttle <span class="hlt">Endeavour</span> as a column of flame hurls it into space. Liftoff of the Shuttle on mission STS-99 occurred at 12:43:40 p.m. EST. Known as the Shuttle Radar Topography Mission (SRTM), STS-99 will chart a new course to produce unrivaled 3-D images of the Earth's surface. The result of the SRTM could be close to 1 trillion measurements of the Earth's topography. The mission is expected to last 11days, with <span class="hlt">Endeavour</span> landing at KSC Tuesday, Feb. 22, at 4:36 p.m. EST. This is the 97th Shuttle flight and 14th for Shuttle <span class="hlt">Endeavour</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1809&hterms=watch&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwatch','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-02PD-1809&hterms=watch&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwatch"><span>STS-113 visitors watch the Space Shuttle <span class="hlt">Endeavour</span> launch</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>KENNEDY SPACE CENTER, FLA. - Among the visitors watching the launch of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-113 are NASA Administrator Sean O'Keefe (top, center) and Glen Mahone, associate administrator for public affairs, NASA (left of O'Keefe). Liftoff occurred ontime at 7:49:47 p.m. EST. The launch is the 19th for <span class="hlt">Endeavour</span>, and the 112th flight in the Shuttle program. Mission STS-113 is the 16th assembly flight to the International Space Station, carrying another structure for the Station, the P1 integrated truss. Also onboard are the Expedition 6 crew, who will replace Expedition 5. <span class="hlt">Endeavour</span> is scheduled to land at KSC after an 11-day journey.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003011','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003011"><span>The Origin of Carbon-Bearing Volatiles in a Continental <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> in the Great Basin: Water Chemistry and Isotope Characterizations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fu, Qi; Socki, Richard A.; Niles, Paul B.; Romanek, Christopher; Datta, Saugata; Darnell, Mike</p> <p>2012-01-01</p> <p><span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> on Earth are active centers in the crust where organic molecules can be synthesized biotically or abiotically under a wide range of physical and chemical conditions [1-3]. Not only are volatile species (CO, CO2, H2, and hydrocarbons) a reflection of deep-seated <span class="hlt">hydrothermal</span> alteration processes, but they also form an important component of biological <span class="hlt">systems</span>. Studying carbon-bearing fluids from <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> is of specific importance to understanding (bio-)geochemical processes within these <span class="hlt">systems</span>. With recent detection of methane in the martian atmosphere [4-7] and the possibility of its <span class="hlt">hydrothermal</span> origin [8, 9], understanding the formation mechanisms of methane may provide constraints on the history of the martian aqueous environments and climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013982','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013982"><span>Castro ring zone: a 4,500-km2 fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in the Challis volcanic field, central Idaho.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Criss, R.E.; Ekren, E.B.; Hardyman, R.F.</p> <p>1984-01-01</p> <p>The largest fossil <span class="hlt">hydrothermal</span> <span class="hlt">system</span> occupying a 4500 km2 area in central Idaho is revealed by delta 18O studies. The remains of this meteoric-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> are preserved within a sharply bounded, 15 km wide, 70-km-diameter annulus of low delta 18O rock (+2.0 to -8.8per mille) termed the Castro ring zone. The zone is centred on a less depleted (+4.5) core zone consisting of granitic rocks of the Castro pluton. This 700-km2 Eocene subvolcanic batholith has intruded, domed, and <span class="hlt">hydrothermally</span> metamorphosed a thick sequence of Challis Volcanics, the stratigraphically low rocks in the 2000-km2 Van Horn Peak and the 1000-km2 Thunder Mountain cauldron complexes being most strongly altered. Less extreme 18O depletions occur in the youngest major ash-flow sheets of these complexes, indicating a vertical 18O gradient. Water/rock ratios of geothermal <span class="hlt">systems</span> are surprisingly insensitive to the circulation scale.-L.-di H.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMOS22A..05F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMOS22A..05F"><span>Steady state and a singular event observed at the TAG <span class="hlt">hydrothermal</span> mound by a long-term monitoring <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujioka, K.; Aoki, M.; Mitsuzawa, K.; Kato, K.; Kinoshita, M.; Nishizawa, A.</p> <p>2005-12-01</p> <p>The steady state variability and occasional O`randomO_L event of <span class="hlt">hydrothermal</span> activity were observed by several long-term monitoring <span class="hlt">systems</span> deployed on the TAG <span class="hlt">hydrothermal</span> mound and observed by submersible video and still cameras in the Mid Atlantic Ridge 26 N. We measured current direction and velocity, visibility, temperature, and salinity of sea water as well as observed newly formed black smokers by video and still camera <span class="hlt">system</span>. Heat flow measurement <span class="hlt">system</span> and an OBSH were also deployed around the central black smoker and newly formed black smokers for more than two weeks. Steady state change of the temperature, current direction and velocity, visibility and pressure change by hydrophone show a regular semidiurnal periodic variation, which may be caused by ocean, and earth tides. A singular event occurred during our research at the TAG <span class="hlt">hydrothermal</span> mound. Small earthquakes beneath the TAG mound were followed by a huge slope failure, which apparently caused by a debris flow, killing swimming eel-like fish. A thin bed of the dead shrimps may be related to a nearly simultaneous increase of hot water flux from vent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS42A..03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS42A..03K"><span>Subseafloor fluid mixing and fossilized microbial life in a Cretaceous 'Lost City'-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Iberian Margin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klein, F.; Humphris, S. E.; Guo, W.; Schubotz, F.; Schwarzenbach, E. M.; Orsi, W.</p> <p>2015-12-01</p> <p>Subseafloor mixing of reduced <span class="hlt">hydrothermal</span> fluids with seawater is believed to provide the energy and substrates needed to support autotrophic microorganisms in the hydrated oceanic mantle (serpentinite). Despite the potentially significant implications for the distribution of microbial life on Earth and other water-bearing planetary bodies, our understanding of such environments remains elusive. In the present study we examined fossilized microbial communities and fluid mixing processes in the subseafloor of a Cretaceous 'Lost City'-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the passive Iberia Margin (ODP Leg 149, Hole 897D). Brucite and calcite co-precipitated from mixed fluids ca. 65m below the Cretaceous palaeo-seafloor at temperatures of 32±4°C within steep chemical gradients (fO2, pH, CH4, SO4, ΣCO2, etc) between weathered, carbonate-rich serpentinite breccia and serpentinite. Mixing of oxidized seawater and strongly reducing <span class="hlt">hydrothermal</span> fluid at moderate temperatures created conditions capable of supporting microbial activity within the oceanic basement. Dense microbial colonies are fossilized in brucite-calcite veins that are strongly enriched in organic carbon but depleted in 13C. We detected a combination of bacterial diether lipid biomarkers, archaeol and archaeal tetraethers analogous to those found in brucite-carbonate chimneys at the active Lost City <span class="hlt">hydrothermal</span> field. The exposure of mantle rocks to seawater during the breakup of Pangaea fueled chemolithoautotrophic microbial communities at the Iberia Margin during the Cretaceous, possibly before the onset of seafloor spreading in the Atlantic. 'Lost City'-type serpentinization <span class="hlt">systems</span> have been discovered at mid-ocean ridges, in forearc settings of subduction zones and at continental margins. It appears that, wherever they occur, they can support microbial life, even in deep subseafloor environments as demonstrated in the present study. Because equivalent <span class="hlt">systems</span> have likely existed throughout most of Earth</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS42A..03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS42A..03K"><span>Subseafloor fluid mixing and fossilized microbial life in a Cretaceous 'Lost City'-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Iberian Margin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klein, F.; Humphris, S. E.; Guo, W.; Schubotz, F.; Schwarzenbach, E. M.; Orsi, W.</p> <p>2014-12-01</p> <p>Subseafloor mixing of reduced <span class="hlt">hydrothermal</span> fluids with seawater is believed to provide the energy and substrates needed to support autotrophic microorganisms in the hydrated oceanic mantle (serpentinite). Despite the potentially significant implications for the distribution of microbial life on Earth and other water-bearing planetary bodies, our understanding of such environments remains elusive. In the present study we examined fossilized microbial communities and fluid mixing processes in the subseafloor of a Cretaceous 'Lost City'-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the passive Iberia Margin (ODP Leg 149, Hole 897D). Brucite and calcite co-precipitated from mixed fluids ca. 65m below the Cretaceous palaeo-seafloor at temperatures of 32±4°C within steep chemical gradients (fO2, pH, CH4, SO4, ΣCO2, etc) between weathered, carbonate-rich serpentinite breccia and serpentinite. Mixing of oxidized seawater and strongly reducing <span class="hlt">hydrothermal</span> fluid at moderate temperatures created conditions capable of supporting microbial activity within the oceanic basement. Dense microbial colonies are fossilized in brucite-calcite veins that are strongly enriched in organic carbon but depleted in 13C. We detected a combination of bacterial diether lipid biomarkers, archaeol and archaeal tetraethers analogous to those found in brucite-carbonate chimneys at the active Lost City <span class="hlt">hydrothermal</span> field. The exposure of mantle rocks to seawater during the breakup of Pangaea fueled chemolithoautotrophic microbial communities at the Iberia Margin during the Cretaceous, possibly before the onset of seafloor spreading in the Atlantic. 'Lost City'-type serpentinization <span class="hlt">systems</span> have been discovered at mid-ocean ridges, in forearc settings of subduction zones and at continental margins. It appears that, wherever they occur, they can support microbial life, even in deep subseafloor environments as demonstrated in the present study. Because equivalent <span class="hlt">systems</span> have likely existed throughout most of Earth</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5067&hterms=space+pv&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dspace%2Bpv','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PD-5067&hterms=space+pv&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dspace%2Bpv"><span>Space Shuttle <span class="hlt">Endeavour</span> reaches Launch Pad 39B</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>After repair of a cracked cleat on the crawler-transporter, Space Shuttle <span class="hlt">Endeavour</span> finally rests on Launch Pad 39B. To the left is the Rotating Service Structure. <span class="hlt">Endeavour</span> is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-98PC-1799&hterms=Ross&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DRoss','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-98PC-1799&hterms=Ross&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DRoss"><span>STS-88 Mission Specialist Ross prepares to enter <span class="hlt">Endeavour</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1998-01-01</p> <p>STS-88 Mission Specialist Jerry L. Ross is assisted with his ascent and re-entry flight suit in the white room at Launch Pad 39A before entering Space Shuttle <span class="hlt">Endeavour</span> for launch. During the nearly 12-day mission, the six-member crew will mate the first two elements of the International Space Station -- the already-orbiting Zarya control module with the Unity connecting module carried by <span class="hlt">Endeavour</span>. He is making his sixth spaceflight and is one of two extravehicular activity crew members on this mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1809&hterms=history+space+rockets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhistory%2Bspace%2Brockets','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-00PP-1809&hterms=history+space+rockets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhistory%2Bspace%2Brockets"><span>Liftoff of Space Shuttle <span class="hlt">Endeavour</span> on mission STS-97</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>Twin columns of flame spew from the solid rocket boosters lifting Space Shuttle <span class="hlt">Endeavour</span> out of the smoke and steam and into the night sky. Liftoff occurred on time at 10:06:01 p.m. EST. The Shuttle and its five-member crew will deliver U.S. solar arrays to the International Space Station and be the first Shuttle crew to visit the Station'''s first resident crew. The 11-day mission includes three spacewalks. This marks the 101st mission in Space Shuttle history and the 25th night launch. <span class="hlt">Endeavour</span> is expected to land at KSC Dec. 11 at 6:19 p.m. EST.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B11A0401P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B11A0401P"><span>Microbial biofilms control economic metal mobility in an acid-sulfate <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips-Lander, C. M.; Roberts, J. A.; Hernandez, W.; Mora, M.; Fowle, D. A.</p> <p>2012-12-01</p> <p>Trace metal cycling in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> has been the subject of a variety of geochemical and economical geology studies. Typically in these settings these elements are sequestered in sulfide and oxide mineral fractions, however in near-surface low-temperature environments organic matter and microorganisms (typically in mats) have been implicated in their mobility through sorption. Here we specifically examine the role of microbial biofilms on metal partitioning in an acid-sulfate <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. We studied the influence of microorganisms and microbial biofilms on trace metal adsorption in Pailas de Aguas I, an acid-sulfate hot spring on the southwest flank of Rincon de la Vieja, a composite stratovolcano in the Guanacaste Province, Costa Rica. Spring waters contain high suspended loads, and are characterized by high T (79.6-89.3oC), low pH (2.6-4), and high ionic strengths (I= 0.5-0.8). Waters contain high concentrations of the biogeochemically active elements Fe (4-6 mmol/l) and SO42- (38 mmol/l), but PO43- are below detection limits (bdl). Silver, Ni, and Mo concentrations are bdl; however other trace metals are present in solution in concentrations of 0.1-0.2 mg/l Cd, 0.2-0.4 mg/l Cr and V, 0.04-1 mg/l Cu,. Preliminary 16S rRNA analyses of microorganisms in sediments reveal several species of algae, including Galderia sp., Cyanidium sp, γ-proteobacteria, Acidithiobacillus caldus, Euryarcheota, and methanogens. To evaluate microbial biofilms' impact on trace metal mobility we analyzed a combination of suspended, bulk and biofilm associated sediment samples via X-ray diffraction (XRD) and trace element sequential extractions (SE). XRD analysis indicated all samples were primarily composed of Fe/Al clay minerals (nontronite, kaolinite), 2- and 6-line ferrihydrite, goethite, and hematite, quartz, and opal-α. SE showed the highest concentrations of Cu, Mo, and V were found in the suspended load. Molybdenum was found primarily in the residual and organic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988JGR....93.4612S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988JGR....93.4612S"><span>Petrology and oxygen isotope geochemistry of a fossil seawater <span class="hlt">hydrothermal</span> <span class="hlt">system</span> within the Solea graben, northern Troodos ophiolite, Cyprus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schiffman, Peter; Smith, Brian M.</p> <p>1988-05-01</p> <p><span class="hlt">Hydrothermal</span> mineral zonations and O isotope patterns of the northern Troodos complex do not parallel the ophiolite pseudostratigraphy, but reflect the convective geometry of an Upper Cretaceous seawater <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. Large areas of the sheeted intrusive complex (SIC), including the subaxial region of the Solea graben, are composed of 18O-rich, subgreenschist mineral assemblages and may represent regions of diffuse seawater recharge. Other areas of the SIC are recrystallized to distinctive epidosite rocks: granular, high-variance assemblages of epidote + quartz ± chlorite that are depleted in 18O, Al2O3, Na2O, K2O, Zr, Cu, and Zn and are enriched in CaO and Sr compared with other mafic volcanic and dike rocks of the Solea graben. Epidosite alteration occurred at temperatures of ˜310-370°C and involved fluids with δ18O values and salinities similar to those of Upper Cretaceous seawater. The epidosite zones are discordant with earlier, mineral/O isotope zonations and with the axis of spreading in the Solea graben, suggesting a postspreading, off-axis origin. The seawater <span class="hlt">hydrothermal</span> <span class="hlt">system</span> responsible for Solea graben massive sulfide deposits was probably driven by hypabyssal intrusions (not exposed), emplaced in a terminal, failed spreading episode. The geometries of O isotope surfaces within the Solea graben imply that the epidosites formed in fossil upflow and deep recharge conduits. Depletions in base metals show that epidosite alteration liberated Cu and Zn to mineralizing fluids within the fossil upflow zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11001052','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11001052"><span>Earthquake-induced changes in a <span class="hlt">hydrothermal</span> <span class="hlt">system</span> on the Juan de Fuca mid-ocean ridge</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson; Hutnak; Dziak; Fox; Urcuyo; Cowen; Nabelek; Fisher</p> <p>2000-09-14</p> <p><span class="hlt">Hydrothermal</span> vents on mid-ocean ridges of the northeast Pacific Ocean are known to respond to seismic disturbances, with observed changes in vent temperature. But these disturbances resulted from submarine volcanic activity; until now, there have been no observations of the response of a vent <span class="hlt">system</span> to non-magmatic, tectonic events. Here we report measurements of <span class="hlt">hydrothermal</span> vent temperature from several vents on the Juan de Fuca ridge in June 1999, before, during and after an earthquake swarm of apparent tectonic origin. Vent fluid temperatures began to rise 4-11 days after the first earthquake. Following this initial increase, the vent temperatures oscillated for about a month before settling down to higher values. We also observed a tenfold increase in fluid output from the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> over a period of at least 80 days, extending along the entire ridge segment. Such a large, segment-wide thermal response to relatively modest tectonic activity is surprising, and raises questions about the sources of excess heat and fluid, and the possible effect on vent biological communities.</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/2015JVGR..304..294C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JVGR..304..294C"><span>Carbon dioxide diffuse emission and thermal energy release from <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at Copahue-Caviahue Volcanic Complex (Argentina)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chiodini, Giovanni; Cardellini, Carlo; Lamberti, María Clara; Agusto, Mariano; Caselli, Alberto; Liccioli, Caterina; Tamburello, Giancarlo; Tassi, Franco; Vaselli, Orlando; Caliro, Stefano</p> <p>2015-10-01</p> <p>The north-western sector of Caviahue caldera (Argentina), close to the active volcanic <span class="hlt">system</span> of Copahue, is characterized by the presence of several <span class="hlt">hydrothermal</span> sites that host numerous fumarolic emissions, anomalous soil diffuse degassing of CO2 and hot soils. In March 2014, measurements of soil CO2 fluxes in 5 of these sites (namely, Las Máquinas, Las Maquinitas I, Las Maquinitas II, Anfiteatro, and Termas de Copahue) allowed an estimation that ~ 165 t of deeply derived CO2 is daily released. The gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges. Gas equilibria within the H-C-O gas <span class="hlt">system</span> indicate the presence of a large, probably unique, single phase vapor zone at 200-210 °C feeding the <span class="hlt">hydrothermal</span> manifestations of Las Máquinas, Las Maquinitas I and II and Termas de Copahue. A natural thermal release of 107 MW was computed by using CO2 as a tracer of the original vapor phase. The magmatic signature of the incondensable fumarolic gases, the wide expanse of the <span class="hlt">hydrothermal</span> areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the Caviahue caldera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70175410','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70175410"><span>Three-dimensional electrical resistivity model of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in Long Valley Caldera, California, from magnetotellurics</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Peacock, Jared R.; Mangan, Margaret T.; McPhee, Darcy K.; Wannamaker, Phil E.</p> <p>2016-01-01</p> <p>Though shallow flow of <span class="hlt">hydrothermal</span> fluids in Long Valley Caldera, California, has been well studied, neither the <span class="hlt">hydrothermal</span> source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic <span class="hlt">system</span> and modeled in 3-D. The preferred electrical resistivity model suggests that the source reservoir is a narrow east-west elongated body 4 km below the west moat. The heat source could be a zone of 2–5% partial melt 8 km below Deer Mountain. Additionally, a collection of hypersaline fluids, not connected to the shallow <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, is found 3 km below the medial graben, which could originate from a zone of 5–10% partial melt 8 km below the south moat. Below Mammoth Mountain is a 3 km thick isolated body containing fluids and gases originating from an 8 km deep zone of 5–10% basaltic partial melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.3268K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.3268K"><span>Organic compounds in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> on the Russian Far East: relevance to the origin of life</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kompanichenko, Vladimir</p> <p></p> <p> instance, Simoneit et al. (2) established that the light oil associated with the Uzon caldera in Kamchatka was formed by pyrolysis of buried algal mats. More interesting would be to determine that the aromatics and alkanes are products of a Fischer-Tropsch type synthesis. Intermediately the possible in-put of the abiotic organics is confirmed with the availability of Cl-alkanes in the hot solution because these compounds cannot be produced in a living organism. Besides, concentrations of even and uneven carbon atoms are similar in the juvenile hot water from the central zone of Kuldur field (the intracontinental part) that indicates their probable abiotic origination, while the uneven carbon atoms much prevail over the even ones (in 5 times) in the lower-temperature meteoric water on the flank. The detected organic compounds could enter into the composi-tion of various prebiotic microsystems or aggregates existed in the changeable <span class="hlt">hydrothermal</span> media suitable for the origin of life. It follows of the inversion approach to the origin of life (Kompanichenko, 2008) that synthesis of other biologically important molecules (sugars, ATP, nucleotides), which are not typical for <span class="hlt">hydrothermal</span> medium, started at the moment of the in-version the ratio "free energy contribution to entropy contribution" in the network of chemical reactions. The re-organized and turned into negentropy way network might promote the syn-thesis of these molecules under higher temperature conditions than revealed for the laboratory experiments in Vitro (50-60C). References. 1. Mukhin L.M., Bondarev V.B., Vakin E.A., Iljukhina I.I., Kalinichenko V.I., Milekhina E.I., Safonova E.N., 1979. Amino acids in <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in Southern Kam-chatka. Doklady AN USSR 244 (4), 974-977, (In Russian). 2. Simoneit, B., Deamer, D.W. and Kompanichenko, V. 2009. Characterization of <span class="hlt">hydrothermally</span> generated oil from the Uzon Caldera, Kamchatka. Applied Geochemistry 24: 303-309. 3. Kompanichenko V.N. 2008. Three stages of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFMSF41A0768V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFMSF41A0768V"><span>Making Water Chemistry Data From Volcano-<span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> Accessible Using Open Source Tools</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Venezky, D. Y.; Mariner, R. H.; Hurwitz, S.; Evans, W. C.</p> <p>2004-12-01</p> <p>Chemical and isotopic data collected over several decades by the U.S. Geological Survey from volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> were recently organized into a web-accessible database for public use. The data were collected by members of the Barnes and/or Mariner projects and were supplemented with data from samples submitted for analysis by other researchers with similar interests. The data are primarily chemical and isotopic analyses of waters (thermal, mineral, or fresh) and associated gas (free and/or dissolved) collected from hot springs, mineral springs, cold springs, geothermal wells, fumaroles, and gas seeps. Additional data for a few streams, lakes, and oil wells are included. The web site follows a multi-stage design, first allowing for basic access to the MySQL database, then a user-friendly GIS (Geographic Information <span class="hlt">System</span>) interface, and finally access to additional documentation and searching features. The initial web pages allow the user to choose the type of data (site, physical parameters, major and minor dissolved constituents, dissolved and free gas composition, water isotopes, and other isotopes) and the sample location. The data are then shown in a table that can be downloaded in several formats. The second stage of the project added an open-source GIS package called WorldKit, which gives easy-to-code and easy-to-use clickable icons on a base map using XML (Extensible Markup Language). WorldKit is also adding a zoom interface (zoomify) that uses new technology to reduce the display time. The final stage of the project involves more complex queries, alternative data presentation, and integrated background information. The more complex queries allow users to select multiple types of data from multiple sites. The data can be found at http://hotspringchem.wr.usgs.gov/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2026W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2026W"><span>Spring Fluids from a Low-temperature <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> at Dorado Outcrop: The First Samples of a Massive Global Flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wheat, C. G.; Fisher, A. T.; McManus, J.; Hulme, S.; Orcutt, B.</p> <p>2015-12-01</p> <p><span class="hlt">Hydrothermal</span> circulation through the volcanic ocean crust extracts about one fourth of Earth's lithospheric heat. Most of this advective heat loss occurs through ridge flanks, areas far from the magmatic influence of seafloor spreading, at relatively low temperatures (2-25 degrees Celsius). This process results in a flux of seawater through the oceanic crust that is commensurate with that delivered to the ocean from rivers. Given this large flow, even a modest (1-5 percent) change in concentration during circulation would impact geochemical cycles for many ions. Until recently such fluids that embody this process have not been collected or quantified despite the importance of this process, mainly because no site of focused, low-temperature discharge has been found. In 2013 we used Sentry (an AUV) and Jason II (an ROV) to generate a bathymetric map and locate springs within a geologic context on Dorado Outcrop, a ridge flank <span class="hlt">hydrothermal</span> <span class="hlt">system</span> that typifies such <span class="hlt">hydrothermal</span> processes in the Pacific. Dorado Outcrop is located on 23 M.y. old seafloor of the Cocos Plate, where 70-90 percent of the lithospheric heat is removed. Spring fluids collected in 2013 confirmed small chemical anomalies relative to seawater, requiring new methods to collect, analyze, and interpret samples and data. In 2014 the submersible Alvin utilized these methods to recover the first high-quality spring samples from this <span class="hlt">system</span> and year-long experiments. These unique data and samples represent the first of their type. For example, the presence of dissolved oxygen is the first evidence of an oxic ridge flank <span class="hlt">hydrothermal</span> fluid, even though such fluids have been postulated to exist throughout a vast portion of the oceanic crust. Furthermore, chemical data confirm modest anomalies relative to seawater for some elements. Such anomalies, if characteristic throughout the global ocean, impact global geochemical cycles, crustal evolution, and subsurface microbial activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4593090','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4593090"><span>Fluid mixing and the deep biosphere of a fossil Lost City-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Iberia Margin</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Klein, Frieder; Humphris, Susan E.; Guo, Weifu; Schubotz, Florence; Schwarzenbach, Esther M.; Orsi, William D.</p> <p>2015-01-01</p> <p>Subseafloor mixing of reduced <span class="hlt">hydrothermal</span> fluids with seawater is believed to provide the energy and substrates needed to support deep chemolithoautotrophic life in the hydrated oceanic mantle (i.e., serpentinite). However, geosphere-biosphere interactions in serpentinite-hosted subseafloor mixing zones remain poorly constrained. Here we examine fossil microbial communities and fluid mixing processes in the subseafloor of a Cretaceous Lost City-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the magma-poor passive Iberia Margin (Ocean Drilling Program Leg 149, Hole 897D). Brucite−calcite mineral assemblages precipitated from mixed fluids ca. 65 m below the Cretaceous paleo-seafloor at temperatures of 31.7 ± 4.3 °C within steep chemical gradients between weathered, carbonate-rich serpentinite breccia and serpentinite. Mixing of oxidized seawater and strongly reducing <span class="hlt">hydrothermal</span> fluid at moderate temperatures created conditions capable of supporting microbial activity. Dense microbial colonies are fossilized in brucite−calcite veins that are strongly enriched in organic carbon (up to 0.5 wt.% of the total carbon) but depleted in 13C (δ13CTOC = −19.4‰). We detected a combination of bacterial diether lipid biomarkers, archaeol, and archaeal tetraethers analogous to those found in carbonate chimneys at the active Lost City <span class="hlt">hydrothermal</span> field. The exposure of mantle rocks to seawater during the breakup of Pangaea fueled chemolithoautotrophic microbial communities at the Iberia Margin, possibly before the onset of seafloor spreading. Lost City-type serpentinization <span class="hlt">systems</span> have been discovered at midocean ridges, in forearc settings of subduction zones, and at continental margins. It appears that, wherever they occur, they can support microbial life, even in deep subseafloor environments. PMID:26324888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26324888','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26324888"><span>Fluid mixing and the deep biosphere of a fossil Lost City-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the Iberia Margin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Klein, Frieder; Humphris, Susan E; Guo, Weifu; Schubotz, Florence; Schwarzenbach, Esther M; Orsi, William D</p> <p>2015-09-29</p> <p>Subseafloor mixing of reduced <span class="hlt">hydrothermal</span> fluids with seawater is believed to provide the energy and substrates needed to support deep chemolithoautotrophic life in the hydrated oceanic mantle (i.e., serpentinite). However, geosphere-biosphere interactions in serpentinite-hosted subseafloor mixing zones remain poorly constrained. Here we examine fossil microbial communities and fluid mixing processes in the subseafloor of a Cretaceous Lost City-type <span class="hlt">hydrothermal</span> <span class="hlt">system</span> at the magma-poor passive Iberia Margin (Ocean Drilling Program Leg 149, Hole 897D). Brucite-calcite mineral assemblages precipitated from mixed fluids ca. 65 m below the Cretaceous paleo-seafloor at temperatures of 31.7 ± 4.3 °C within steep chemical gradients between weathered, carbonate-rich serpentinite breccia and serpentinite. Mixing of oxidized seawater and strongly reducing <span class="hlt">hydrothermal</span> fluid at moderate temperatures created conditions capable of supporting microbial activity. Dense microbial colonies are fossilized in brucite-calcite veins that are strongly enriched in organic carbon (up to 0.5 wt.% of the total carbon) but depleted in (13)C (δ(13)C(TOC) = -19.4‰). We detected a combination of bacterial diether lipid biomarkers, archaeol, and archaeal tetraethers analogous to those found in carbonate chimneys at the active Lost City <span class="hlt">hydrothermal</span> field. The exposure of mantle rocks to seawater during the breakup of Pangaea fueled chemolithoautotrophic microbial communities at the Iberia Margin, possibly before the onset of seafloor spreading. Lost City-type serpentinization <span class="hlt">systems</span> have been discovered at midocean ridges, in forearc settings of subduction zones, and at continental margins. It appears that, wherever they occur, they can support microbial life, even in deep subseafloor environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V11E..07C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V11E..07C"><span>Permeability Reduction in Passively Degassing Seawater-dominated Volcanic-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>: Processes and Perils on Raoul Island, Kermadecs (NZ)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christenson, B. W.; Reyes, A. G.</p> <p>2014-12-01</p> <p>The 2006 eruption from Raoul Island occurred apparently in response to local tectonic swarm activity, but without any precursory indication of volcanic unrest within the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> on the island. The eruption released some 200 T of SO2, implicating the involvement of a deep magmatic vapor input into the <span class="hlt">system</span> during/prior to the event. In the absence of any recognized juvenile material in the eruption products, previous explanations for this eruptive event focused on this vapor being a driving force for the eruption. In 2004, at least 80 T/d of CO2 was escaping from the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, but mainly through areas that did not correspond to the 2006 eruption vents. The lack of a pre-eruptive <span class="hlt">hydrothermal</span> <span class="hlt">system</span> response related to the seismic event in 2006 can be explained by the presence of a <span class="hlt">hydrothermal</span> mineralogic seal in the vent area of the volcano. Evidence for the existence of such a seal was found in eruption deposits in the form of massive fracture fillings of aragonite, calcite and anhydrite. Fluid inclusion homogenization temperatures in these phases range from ca. 140 °C to 220 °C which, for pure water indicate boiling point depths of between 40 and 230 m assuming a cold hydrostatic pressure constraint. Elevated pressures behind this seal are consistent with the occurrence of CO2 clathrates in some inclusion fluids, indicating CO2 concentrations approaching 1 molal in the parent fluids. Reactive transport modeling of magmatic volatile inputs into what is effectively a seawater-dominated <span class="hlt">hydrothermal</span> <span class="hlt">system</span> provide valuable insights into seal formation. Carbonate mineral phases ultimately come to saturation along this flow path, but we suggest that focused deposition of the observed massive carbonate seal is facilitated by near-surface boiling of these CO2-enriched altered seawaters, leading to large degrees of supersaturation which are required for the formation of aragonite. As the seal grew and permeability declined, pore pressures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016160','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016160"><span>Organic matter in <span class="hlt">hydrothermal</span> metal ores and <span class="hlt">hydrothermal</span> fluids</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Orem, W.H.; Spiker, E. C.; Kotra, R.K.</p> <p>1990-01-01</p> <p>Massive polymetallic sulfides are currently being deposited around active submarine <span class="hlt">hydrothermal</span> vents associated with spreading centers. Chemoautolithotrophic bacteria are responsible for the high production of organic matter also associated with modern submarine <span class="hlt">hydrothermal</span> activity. Thus, there is a significant potential for organic matter/metal interactions in these <span class="hlt">systems</span>. We have studied modern and ancient <span class="hlt">hydrothermal</span> metal ores and modern <span class="hlt">hydrothermal</span> fluids in order to establish the amounts and origin of the organic matter associated with the metal ores. Twenty-six samples from modern and ancient <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> were surveyed for their total organic C contents. Organic C values ranged from 0.01% to nearly 4.0% in these samples. Metal ores from modern and ancient sediment-covered <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> had higher organic C values than those from modern and ancient <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> lacking appreciable sedimentary cover. One massive pyrite sample from the Galapagos spreading center (3% organic C) had stable isotope values of -27.4% (??13C) and 2.1% (??15N), similar to those in benthic siphonophors from active vents and distinct from seep sea sedimentary organic matter. This result coupled with other analyses (e.g. 13C NMR, pyrolysis/GC, SEM) of this and other samples suggests that much of the organic matter may originate from chemoautolithotrophic bacteria at the vents. However, the organic matter in <span class="hlt">hydrothermal</span> metal ores from sediment covered vents probably arises from complex sedimentary organic matter by <span class="hlt">hydrothermal</span> pyrolysis. The dissolved organic C concentrations of <span class="hlt">hydrothermal</span> fluids from one site (Juan de Fuca Ridge) were found to be the same as that of background seawater. This result may indicate that dissolved organic C is effectively scavenged from <span class="hlt">hydrothermal</span> fluids by biological activity or by co-precipitation with metal ores. ?? 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUSM.H23A..13B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUSM.H23A..13B"><span>Patterns of Fluid Circulation and Steam Generation in Caldera-Hosted <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barnard, M. E.; Cook, S. J.</p> <p>2009-05-01</p> <p>Steam formation is an important mechanism powering near surface phenomena in active <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> (e.g., Yellowstone) and an established ore deposition mechanism in ancient equivalents (e.g., Creede). To gain insights into factors controlling steam formation and distribution in these <span class="hlt">systems</span>, a series of steady-state numerical models were run on a hypothetical caldera-hosted <span class="hlt">system</span> based on characteristics of a representative suite of calderas (e.g., Yellowstone, Valles, Creede). Base model conditions consisted of (1) a 10 km-wide caldera with a flat floor and rim height of 800 m; (2) a 500 C intrusion 1.5 km below the caldera centre; (3) a regional conductive heat flux twice continental average (0.10 W/m2); (4) host rock thermal conductivity of 2.5 W/m C, density 2650 kg/m3 and pore fraction 0.05. An impermeable intrusion was modeled with a 500 m wide surrounding region with a permeability (k) 10-3 m2 less than the <span class="hlt">system</span> meant to represent a ductile region produced by elevated temperature (T > 350 C). The remainder of the <span class="hlt">system</span> was given homogenous permeability. Cylindrical coordinates were used to represent caldera geometry. For these conditions, a minimum k = 10-15 m2 was required to achieve the target thermal condition of T approximately 220 C at 300 m below ground surface observed in active <span class="hlt">systems</span> (e.g., Yellowstone). This model also resulted in a continuous steam plume originating at the intrusive contact that reached within 300 m of the surface along the edges of the caldera ~2 km from caldera centre. Models with k < 10-15 m2 produced steam, but at greater depths and failed to match the target conditions. Models with intrusion temperatures reduced by 20% shifted the steam plume toward the caldera centre and reduced its volume, but still achieved target conditions. Increasing intrusion temperature by 10% produced a second distinct plume at the caldera centre that also achieved target conditions. Increasing the rim height for these conditions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V11E2549S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V11E2549S"><span>Preliminary Modeling of Two-Phase Flow at the Main <span class="hlt">Endeavour</span> Vent Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, S.; Lowell, R. P.</p> <p>2011-12-01</p> <p>The high temperature <span class="hlt">hydrothermal</span> vents of Main <span class="hlt">Endeavour</span> Field (MEF), Juan de Fuca ridge exhibited quasi-steady North-South trending spatial gradients of both temperature and salinity for more than a decade before a magmatic event changed the vent characteristics. In order to explain these observations, we construct two-dimensional numerical models of two-phase <span class="hlt">hydrothermal</span> flow of the MEF. We consider both along-axis and across-axis simulations, taking into account the vent field geometry and incorporating various parameters, such as different basal temperature distributions and permeability structures that might affect the vent fluid temperature and chemistry. Preliminary results from across-axis models, in which the basal temperature decreases linearly away from the ridge axis and results in a single high-temperature plume, indicate that basal temperature alone does not affect steady-state vent temperature and salinity of the vents. Simulations that include the presence of a high-permeability extrusive layer 2A atop the spreading ridge results in a zone of narrower and lower temperature venting. The effect of a low permeability zone of anhydrite would tend to mitigate the decrease in temperature, however. Along-axis simulations performed to date, with an extended uniform high temperature basal boundary, produce multiple plumes; but the plumes do not exhibit a strong along-axis gradient in vent salinity or temperature as observed at the MEF. These preliminary results suggest that the observed N-S gradient in temperature and salinity at MEF reflects interplay between heat source and either near the surface or deep-seated heterogeneous permeability structures. Three-dimensional simulations might ultimately be required to understand <span class="hlt">hydrothermal</span> circulation at the MEF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B51A0345M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B51A0345M"><span>Strontium and oxygen isotopic profiles through 3 km of <span class="hlt">hydrothermally</span> altered oceanic crust in the Reykjanes Geothermal <span class="hlt">System</span>, Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marks, N. E.; Zierenberg, R. A.; Schiffman, P.</p> <p>2010-12-01</p> <p>The Iceland Deep Drilling Program well of opportunity RN-17 was drilled 3 km into a section of <span class="hlt">hydrothermally</span> altered basaltic crust in the Reykjanes geothermal <span class="hlt">system</span> in Iceland. The <span class="hlt">system</span> is located on the landward extension of the Mid-Atlantic Ridge, and the circulating <span class="hlt">hydrothermal</span> fluid is modified seawater, making Reykjanes a useful analogue for mid-oceanic ridge <span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Whole rock oxygen isotope ratios range from -0.13 to 3.61‰, which are significantly depleted relative to fresh MORB (5.8±0.2‰). If oxygen isotope exchange between fluid and rock proceeded under equilibrium in a closed <span class="hlt">system</span>, the bulk of the exchange must have occurred in the presence of a meteoric- as opposed to seawater-derived fluid. The concentrations of Sr in the altered basalt range from well below to well above concentrations in fresh rock, and appear to be strongly correlated with the dominant alteration mineralogy, although there is no correlation with 87Sr/86Sr isotopic ratios. Whole rock Sr isotopic ratios ranged from 0.70329 in the least altered crystalline basalt, to 0.70609 in the most altered hyaloclastite samples; there is no correlation with depth. Sr isotopic variation in epidote grains measured by laser ablation MC-ICP-MS ranged from 0.70353 to 0.70731. Three depth intervals have distinctive isotopic signatures, at 1000 m, 1350 m, and 2000 m depth, where 87Sr/86Sr ratios are elevated (mean value >0.7050) relative to background levels (mean altered basalt value ~0.7042). These areas are proximal to feed zones, and the 1350 m interval directly overlies the transition from dominantly extrusive to intrusive lithologies. Strontium and oxygen isotope data indicate that the greenschist-altered basalts were in equilibrium with modified <span class="hlt">hydrothermal</span> fluids at a relatively high mean water/rock mass ratios (generally in the range 1-3), and require the presence of both meteoric- and seawater-derived recharge fluids at various stages in the <span class="hlt">hydrothermal</span> history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7328K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7328K"><span>Fluxes of magmatic chlorine and sulfur from volcano-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>. Examples for Northern Kuril Islands Paramushir and Shiashkotan.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalacheva, Elena; Taran, Yuri</p> <p>2015-04-01</p> <p>The total flux of components degassed from the magma through persistently degassing volcanoes comprises of the volcanic vapor flux from fumaroles to the atmosphere, diffuse flux through volcanic slopes and the <span class="hlt">hydrothermal</span> flux to the local hydrologic network. The <span class="hlt">hydrothermal</span> flux may be provided by the discharge of fluids formed at depth over the magma body and/or by acid waters which are formed by the absorption of the ascending volcanic vapor by shallow ground. The anion composition (Cl and SO4) of the discharging thermal waters from a volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span> originates from the volcanic vapor and should be taken into account in estimations of the magmatic volatile output and volatile recycling in subduction zones. Here we report the chemical (major and trace elements) and isotopic composition of acidic and neutral thermal waters, chemical and isotopic composition of volcanic vapors and solute fluxes from the northern Kurilian islands Paramushir (Ebeko volcanic center) and Shiashkotan (volcanoes Sinarka and Kuntomintar). The total measured outputs of chloride and sulfur from the <span class="hlt">system</span> in 2006-2014 were estimated on average as 730 g/s and 980 g/s, respectively, which corresponds to the equivalent fluxes of 64 t/d of HCl and 169 t/d of SO2. These values are one order of magnitude higher than the fumarolic output of Cl and S from the low-temperature fumarolic field of Ebeko (<120°C). The estimated discharge rate of hot (85°C) water from the <span class="hlt">system</span> with ~ 3500 ppm of chloride is about 0.3 m3s-1 which is among the highest hot water natural outputs ever measured for a volcano-<span class="hlt">hydrothermal</span> <span class="hlt">system</span>. The total <span class="hlt">hydrothermal</span> discharge of Cl and S from Shiashkotan island to the Sea of Okhotsk associated with magmatic activity of two volcanoes is estimated as ca. 20 t/d and 40 t/d, respectively, which is close to the fumarolic output from both volcanoes (Sinarka and Kuntomintar) estimated using the chemistry and flow rates of fumaroles those measured temperature is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816348P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816348P"><span>Geochemistry of the <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the Jujuy Province, Argentina, and relationship with the regional geology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peralta Arnold, Yesica; Cabassi, Jacopo; Tassi, Franco; Caffe, Pablo; Vaselli, Orlando</p> <p>2016-04-01</p> <p>The western sector of the Jujuy province (22°-24° S), Argentina, basically consisting of the Puna region (from 3,500 to 4,700 m a.s.l.) that borders the Central Volcanic Zone (CVZ), is characterized by sub-meridional ridges that alternate with elongated basins and by extremely voluminous intermediate and silicic ignimbrite deposits, the latter being related to late miocenic and pliocenic calderas and central volcanic edifices. In this region, several <span class="hlt">hydrothermal</span> discharges with outlet temperatures up to 62°C occur. Among them, the Coranzulí and Pairique thermal emissions show a spatial relationship with miocenic volcanic complexes, whereas other thermal manifestations (Queñual, Orosmayo, Pirquitas, Arizutar, Cono Panizo and Rachaite) are clearly controlled by the local structural setting. Most of these thermal waters have relatively high total dissolved solids (TDS up to 46,500 mg/L), an alkaline-chloride composition and significant concentrations of B, NH4 and SiO2, i.e. they show the typical geochemical features of geothermal brine. Exceptions are the Coranzulí, Orosmayo and Rachaite springs, mainly fed by a shallow Na(Ca)-bicarbonate aquifer. The eastern sector of the province consists of the Eastern Cordillera, composed of a proterozoic basement constituted by the sedimentary sequences of the Puncoviscana Fm, and the Subandean Range, which shows wide east-vergence anticlines whose detachment levels are Silurian-Devonian shales. Both regions are separated by a major thrust that rises the Proterozoic and Eopaleozoic sequences over the Subandean <span class="hlt">System</span>. The thermal waters in the Eastern Cordillera, namely Termas de Reyes, are characterized by alkaline-sulfate composition, temperature of ≈50°C and neutral pH. In contrast, in the Subandean Ranges, which is separated from the Eastern Cordillera by a thrust rising Proterozoic and Eopaleozoic sequences over the Subandean <span class="hlt">System</span>, the Aguas Calientes springs are characterized by low temperature (from 21°C to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BGeo...11.5687M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BGeo...11.5687M"><span>Fluid chemistry of the low temperature hyperalkaline <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Prony Bay (New Caledonia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Monnin, C.; Chavagnac, V.; Boulart, C.; Ménez, B.; Gérard, M.; Gérard, E.; Pisapia, C.; Quéméneur, M.; Erauso, G.; Postec, A.; Guentas-Dombrowski, L.; Payri, C.; Pelletier, B.</p> <p>2014-10-01</p> <p>H 11) are not significantly different from one site to the other although the sites are several kilometres away from each other and are located on different ultramafic substrata. The very low salinity of the hyperalkaline endmembers shows that seawater does not percolate through the ultramafic formation. Mixing of the hyperalkaline <span class="hlt">hydrothermal</span> endmember with local seawater produces large ranges and very sharp gradients of pH, salinity and dissolved element concentrations. There is a major change in the composition of the water samples at a pH around 10, which delimitates the marine environment from the hyperalkaline environment. The redox potential evolves toward negative values at high pH indicative of the reducing conditions due to bubbling of the H2-rich gas. The calculation of the mineral saturation states carried out for the Na-K-Ca-Mg-Cl-SO4-DIC-SiO2-H2O <span class="hlt">system</span> shows that this change is due to the onset of brucite formation. While the saturation state of the Ca carbonates over the whole pH range is typical of that found in a normal marine environment, Mg- and Mg-Ca carbonates (magnesite, hydromagnesite, huntite, dolomite) exhibit very large supersaturations with maximum values at a pH of around 10, very well marked for the Bain des Japonais, emphasizing the role of water mixing in mineral formation. The discharge of high-pH waters of meteoric origin into the lagoon marine environment makes the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> of Prony Bay unique compared to other low temperature serpentinizing environments such as Oman (fully continental) or Lost City (fully marine).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T51B2572P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T51B2572P"><span>Newly discovered <span class="hlt">hydrothermal</span> <span class="hlt">system</span> on the Alarcón Rise, Mexico</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.; Martin, J. F.; Nieves-Cardoso, C.</p> <p>2012-12-01</p> <p>The Alarcón Rise lies at the mouth of the Gulf of California, and is the last segment of the East Pacific Rise before the plate boundary redirects into the gulf. As part of MBARI's expedition to the gulf in 2012, the neovolcanic zone of the entire ridge segment was mapped by MBARI's mapping AUV. 110 potential <span class="hlt">hydrothermal</span> chimneys were identified in the new high resolution maps, and 70 were visited with the ROV Doc Ricketts, after having been sought in vain without the maps on an expedition in 2003. Two active vent fields were found, and have been named Meyibó and Ja sít from local native languages. They lie 2.5km apart at ~2300m depth, and are associated with a large, young sheet flow 1/3 of the way along the ridge from the south, on the most inflated part of the ridge. The southern field, Meyibó, contains 14 active chimneys (confirmed with ROV observations) nestled in grabens of several highly fractured cones surrounded by the sheet flow, and generally aligned with its discontinuous, 8km-long fissure <span class="hlt">system</span>. The northern field, Ja sít, is a broad cluster of 8 active chimneys (also confirmed) rising above the sheet flow's channel <span class="hlt">system</span>, more than 150m from the fissure. The chimneys stand as tall as 18 m. The most vigorous vent "black smoke" (mineral-rich fluid) >300°C and others are bathed in "white smoke". The active chimneys are populated with bacterial mat and dense clumps of Riftia pachyptila with tubes as long as 1.5m. Abundant limpets, Bythograea thermydron and galatheid crabs, and the pink vent fish Thermarces cerberus were on and near the giant tube worms. Alvinellid worms were observed at 2 chimneys. Some cracks in nearby lava flows vented clear fluid and were populated with tubeworms or Calyptogena magnifica clams. Several chimneys exhibited signs of waning activity: dead tubeworms were still attached and only a minor portion of the edifice supported bacterial mat and live tubeworms. Inactive chimneys are more numerous (48 were confirmed with ROV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA618043','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA618043"><span>Investigating the Relationship between Fin Whales, Zooplankton Concentrations and <span class="hlt">Hydrothermal</span> Venting on the Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2014-09-30</p> <p>1992). Composition of a deep scattering layer overlying a mid - ocean ridge <span class="hlt">hydrothermal</span> plume, Mar. Biol. 113, 517-526. Croll, D. A., Clark, C. W...<span class="hlt">Endeavour</span> segment of the Juan de Fuca Ridge (Weekly et al., 2013) that included a network of eight ocean bottom seismometers (OBSs) that operated from... mid -1990s, the Institute of Ocean Sciences in Sidney, BC conducted summer cruises to the <span class="hlt">Endeavour</span> to collect a series of plankton net tows in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=paper&pg=4&id=EJ1113099','ERIC'); return false;" href="http://eric.ed.gov/?q=paper&pg=4&id=EJ1113099"><span>Exploring Talenting: Talent Management as a Collective <span class="hlt">Endeavour</span></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>Gold, Jeff; Oldroyd, Tony; Chesters, Ed; Booth, Amanda; Waugh, Adrian</p> <p>2016-01-01</p> <p>Purpose: This paper seeks to show appreciation for the collective <span class="hlt">endeavour</span> of work practices based on varying degrees of dependence, interdependence and mutuality between at least two people. Such dependencies have to be concerned with how talent is used and how this use is an interaction between people, a process called talenting. The aim of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982JVGR...12..101V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982JVGR...12..101V"><span>Stable isotopes of helium, nitrogen and carbon in a coastal submarine <span class="hlt">hydrothermal</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vidal, Francisco V.; Welhan, John; Vidal, Victor M. V.</p> <p>1982-03-01</p> <p>Geothermal gases from submarine and subaerial hot springs in Ensenada, Baja California Norte, Mexico, were sampled for determination of gas chemistry and helium, nitrogen and stable carbon isotope composition. The submarine hot spring gas is primarily nitrogen (56.1% by volume) and methane (43.5% by volume), whereas nearby subaerial hot spring gases are predominantly nitrogen (95-99% by volume). The N 2/Ar ratios and σ 15N values of the subaerial hot spring gas indicate that it is atmospheric air, depleted in oxygen and enriched in helium. The submarine hot spring gas is most probably derived from marine sediments of Cretaceous age rich in organic matter. CH 4 is a major component of the gas mixture ( σ 13C = -44.05% 0), with only minor amounts of CO 2 ( σ13C= -10.46% 0). The σ 15N of N 2 is + 0.2% 0 with a very high N 2/Ar ratio of 160. The calculated isotopic equilibra tion temperature for CH 4CO 2 carbon exchange at depth in the Punta Banda submarine geothermal field is approximately 200°C in agreement with other geothermometry estimates. The 3He/ 4He ratios of the hot spring gases range from 0.3 to 0.6 times the atmospheric ratio, indicating that helium is predominantly derived from the radioactive decay of U and Th within the continental crust. Thus, not all submarine <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> are effective vehicles for mantle degassing of primordial helium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22139512','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22139512"><span>Modeling free energy availability from Hadean <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> to the first metabolism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simoncini, E; Russell, M J; Kleidon, A</p> <p>2011-12-01</p> <p>Off-axis <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> (HSs) are seen as the possible setting for the emergence of life. As the availability of free energy is a general requirement to drive any form of metabolism, we ask here under which conditions free energy generation by geologic processes is greatest and relate these to the conditions found at off-axis HSs. To do so, we present a conceptual model in which we explicitly capture the energetics of fluid motion and its interaction with exothermic reactions to maintain a state of chemical disequilibrium. Central to the interaction is the temperature at which the exothermic reactions take place. This temperature not only sets the equilibrium constant of the chemical reactions and thereby the distance of the actual state to chemical equilibrium, but these reactions also shape the temperature gradient that drives convection and thereby the advection of reactants to the reaction sites and the removal of the products that relate to geochemical free energy generation. What this conceptual model shows is that the positive feedback between convection and the chemical kinetics that is found at HSs favors a greater rate of free energy generation than in the absence of convection. Because of the lower temperatures and because the temperature of reactions is determined more strongly by these dynamics rather than an external heat flux, the conditions found at off-axis HSs should result in the greatest rates of geochemical free energy generation. Hence, we hypothesize from these thermodynamic considerations that off-axis HSs seem most conducive for the emergence of protometabolic pathways as these provide the greatest, abiotic generation rates of chemical free energy.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21C1534P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21C1534P"><span>Hydrogeological and geochemical modeling of <span class="hlt">hydrothermal</span> fluids circulation in active ultramafic-hosted <span class="hlt">systems</span> under CAST3M</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perez, F.; Mugler, C.; Jean-Baptiste, P.; Charlou, J. L.; Donval, J.; Vidal, O.; Marcailloux, C.; Munoz, M.</p> <p>2010-12-01</p> <p><span class="hlt">Hydrothermal</span> circulation at mid-ocean ridges is a fundamental process that impacts the transfer of energy and water from the interior of the Earth to the Crust, Hydrosphere and biosphere. Along the Mid-Atlantic Ridge (MAR), at precisely located ultramafic-hosted <span class="hlt">systems</span>, important fluxes of heat, hydrogen and Iron are observed (Charlou et al., 2010 AGU Monograph series). It is now demonstrated that high and low-temperature <span class="hlt">hydrothermal</span> activity and mantle degassing are indicators of ongoing serpentinization process. For a real understanding of this process and to estimate heat and hydrogen fluxes, numerical modeling leant on field data and laboratory experiments can yield results of interest. We thus developed a thermo-hydrogeological numerical model using a Finite Volume method to simulate heat driven fluid flows in geological layers, encoded under CAST3M, and presented here. For homogeneous medias, we successfully obtained exiting fluid temperatures that natural <span class="hlt">hydrothermal</span> fluids usually reach. Considering laboratory experiments, we coupled, under CAST3M, our thermo-hydrogeological model to a geochemical model of serpentinization reaction. This last model is based on a reaction front velocity model calibrated by laboratory experiments. Primary results are presented here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SolE....7..557C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SolE....7..557C"><span>Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> dynamics of a restless caldera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coco, A.; Gottsmann, J.; Whitaker, F.; Rust, A.; Currenti, G.; Jasim, A.; Bunney, S.</p> <p>2016-04-01</p> <p>Ground deformation and gravity changes in restless calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow <span class="hlt">hydrothermal</span> activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). <span class="hlt">Hydrothermal</span> fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.<p class="p">Informed by constraints available for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V33B4847H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V33B4847H"><span>Hydrogen Isotope Evidence for Giant Meteoric-<span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> Associated with Extension and Magmatism in the Southern Canadian Cordillera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holk, G. J.; McCarthy, A.</p> <p>2014-12-01</p> <p>Over 400 published mineral and fluid inclusion δD values from the southern Canadian Cordillera and our new data from the Eocene Penticton Group Volcanics and Coryell Intrusive Suite of the Southern Omineca Belt and the Western Metamorphic Belt of the Central Coast Orogen are compiled using GIS. δDH2O is estimated using published D/H fractionation factors at 400°C; the error is ±20‰, small enough to distinguish deep magmatic/metamorphic fluids from meteoric-<span class="hlt">hydrothermal</span> fluids. Histogram plots of δDH2O values estimated from minerals reveal peaks at δD = -60‰ (deep fluid) and ­-110‰ (Early Cenozoic meteoric-<span class="hlt">hydrothermal</span> fluid); this provides a clear distinction between the two kinds of fluid. Our analysis reveals that syn-extensional meteoric-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span> (δDH2O < -80‰) affected the eastern margin of the Coast Ranges Batholith between latitude 49° and 55° and the Omineca Belt between latitude 49° and 52°45'; both regions were affected by detachment faulting during late stages of magmatism in the Early Cenozoic (e.g., Parrish et al., 1988; Crawford et al., 2009). Zones that escaped the effects of meteoric-<span class="hlt">hydrothermal</span> <span class="hlt">systems</span>, preserving the D/H signature of deep fluids (δD > -80‰), include the Western Metamorphic Belt, the Western and Central Coast Ranges Batholith, the belt of Jurassic metamorphism that extends from the Cariboo Mountains to the Purcell Mountains, and the deepest structural levels of the Shuswap Metamorphic Core Complex; most of these samples have quartz-feldspar 18O/16O fractionations indicative of magmatic temperatures. High δDH2O values (> -50‰) suggest seawater alteration of the plutons of Vancouver Island (Magaritz and Taylor, 1986). Histogram plots of vein quartz fluid inclusion δD values (Nesbitt and Muehlenbachs, 1995) reveal three peaks that include the two produced by the mineral δD values, but these data are dominated by a large peak at δD = -150, a value similar to modern meteoric waters in the region</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1212826I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1212826I"><span><span class="hlt">Hydrothermal</span> fluids vented at shallow depths at the Aeolian islands: relationships with volcanic and geothermal <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Italiano, Francesco; Caracausi, Antonio; Longo, Manfredi; Maugeri, Roberto; Paonita, Antonio</p> <p>2010-05-01</p> <p> lower values detected in venting gases from active volcanoes (e.g. Vulcano and Panarea). The explanation of such a difference is not related to the volcanic activity at all, but to the parent mantle that in the western side looks to be less contaminated compared to the eastern side. Crustal contamination has been invoked by several authors as the main factor that caused the dramatic 3He/4He decrease. Although the parent mantle produced magmas with different isotopic signature, the gas phase looks similar. To explain the results of the chemical analyses it is proposed that similar deep boundary conditions (pressure, temperature, oxidation level) act as buffers for the chemical composition of the venting gases. With the aim of investigating their origin, estimations of the deep equilibration conditions have been carried out. The reactive compounds detected in the sampled gases, largely used for geothermometric and geobarometric considerations of <span class="hlt">hydrothermal</span> fluids were used in a <span class="hlt">system</span> based on the CH4-CO-CO2 contents assuming the presence of a boiling aqueous solution. The equilibrium constants of the adopted reactions are a function of temperature and oxygen fugacity, being the latter buffered by the mineral assemblage of the host rocks. Due to the similarity in the chemical composition of the gases vented at all the islands, a theoretical model developed to interpret the chemical composition of the gases released at Panarea during the last volcanic crisis is here applied. The results have shown that geothermal boiling <span class="hlt">systems</span> are detectable at all the islands with temperatures up to 350°C. The adopted geo-thermobarometric <span class="hlt">system</span> is more sensitive to the contents of CO and CH4 than that of CO2, implying that although GWI induce modifications in the chemical composition, the estimated equilibrium temperatures do not change very much for variations of the CO2 content in the range of several volume percent, thus, whether or not the gaseous mixture underwent GWI. Moreover</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.V21D0764K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V21D0764K"><span>Geology of the Early Archean Mid-Ocean Ridge <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> in the North Pole Dome, Pilbara Craton, Western Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitajima, K.; Maruyama, S.</p> <p>2007-12-01</p> <p>An Archean <span class="hlt">hydrothermal</span> <span class="hlt">system</span> in the North Pole Dome, Pilbara Craton is associated with extensive fluid circulation driven by numerous extensional fracture <span class="hlt">systems</span> and the underlying heat source. The fracture <span class="hlt">system</span> is now occupied by abundant fine-grained quartz aggregate, hence we call this as silica dikes. Some of the fracture <span class="hlt">system</span> extends deeper structural levels as listric normal faults down to 1000 m depth in the MORB crust. Barite-bearing fine-grained quartz predominant mineralogy indicates the extensive development of fracturing and quenching in a short time. Accompanying the fluid circulation, the extensive metasomatism proceeded to form the four different chemical courses, (1) silicification, (2) carbonation, (3) potassium-enrichment, and (4) Fe- enrichment. Silicification occurs along the silica dikes, carbonated greenstones are distributed relatively shallower level. Potassium-enriched (mica-rich) greenstones occur at the top of the greenstone sequence, and Fe-enriched (chlorite-rich) greenstones are distributed at lower part of the basaltic greenstones. The down going fluid precipitated carbonate-rich layer at shallow levels, whereas depleted in SiO2. Then, the fluid went down to more deeper level, and was dissolved SiO2 at high temperature (~350°C) and chlorite-rich greenstone was formed by water-rock interaction. The upwelling fluid precipitated dominantly SiO2 and formed silica dikes. Silica dikes cement the fractures formed by extensional faulting at earliest stage of development of oceanic crust. Therefore, the <span class="hlt">hydrothermal</span> <span class="hlt">system</span> must have related to normal fault <span class="hlt">system</span> simultaneously with MORB volcanism. Particularly the greenish breccia with cherty matrix (oregano chert) was formed at positions by upwelling near ridge axis. After the horizontal removal of MORB crust from the ridge-axis with time, the propagating fracture into deeper levels, transports <span class="hlt">hydrothermal</span> fluids into 500-1000 m depth range where metasomatic element exchange between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B11D..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B11D..02S"><span><span class="hlt">Hydrothermal</span> Biogeochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shock, E.; Havig, J.; Windman, T.; Meyer-Dombard, D.; Michaud, A.; Hartnett, H.</p> <p>2006-12-01</p> <p>Life in hot spring ecosystems is confronted with diverse challenges, and the responses to those challenges have dynamic biogeochemical consequences over narrow spatial and temporal scales. Within meters along hot spring outflow channels at Yellowstone, temperatures drop from boiling, and the near-boiling conditions of hot chemolithotrophic communities, to those that permit photosynthesis and on down to conditions where nematodes and insects graze on the edges of photosynthetic mats. Many major and trace element concentrations change only mildly in the water that flows through the entire ecosystem, while concentrations of other dissolved constituents (oxygen, sulfide, ammonia, total organic carbon) increase or decrease dramatically. Concentrations of metals and micronutrients range from toxic to inadequate for enzyme synthesis depending on the choice of hot spring. Precipitation of minerals may provide continuous growth of microbial niches, while dissolution and turbulent flow sweeps them away. Consequently, microbial communities change at the meter scale, and even more abruptly at the photosynthetic fringe. Isotopic compositions of carbon and nitrogen in microbial biomass reflect dramatic and continuous changes in metabolic strategies throughout the <span class="hlt">system</span>. Chemical energy sources that support chemolithotrophic communities can persist at abundant or useless levels, or change dramatically owing to microbial activity. The rate of temporal change depends on the selection of hot spring <span class="hlt">systems</span> for study. Some have changed little since our studies began in 1999. Others have shifted by two or more units in pH over several years, with corresponding changes in other chemical constituents. Some go through daily or seasonal desiccation cycles, and still others exhibit pulses of changing temperature (up to 40°C) within minutes. Taken together, <span class="hlt">hydrothermal</span> ecosystems provide highly manageable opportunities for testing how biogeochemical processes respond to the scale of</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>Diversity of Archaeal Consortia in an Arsenic-Rich <span class="hlt">Hydrothermal</span> <span class="hlt">System</span></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 sites with dissolved methane contain 106 cells of methanogenic archaea per gram while non-specific samples from sites 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 sites. 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 site included only Crenarchaeal clones within the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21A1482E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21A1482E"><span>Barite chimneys from two <span class="hlt">hydrothermal</span> sites along the slow-spreading Arctic Ridge <span class="hlt">system</span>: Initial isotope and mineralogical results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eickmann, B.; van Zuilen, M. A.; Thorseth, I. H.; Pedersen, R.</p> <p>2010-12-01</p> <p>Two <span class="hlt">hydrothermal</span> sites along the slow-spreading Arctic Ridge <span class="hlt">systems</span>, the Jan Mayen vent fields (JMVFs) and the recently discovered Loki’s Castle <span class="hlt">hydrothermal</span> field (LCHF) contains numerous barite chimneys partially covered by microbial mats. The JMVFs are located at 71°N on the south-western Mohns Ridge, approximately 50 km north of the Jan Mayen fracture zone. The LCHF is located at 73.5°N on an axial volcanic ridge where the Mohns Ridge transitions into the Knipovich Ridge and consists of two venting areas. Active <span class="hlt">hydrothermal</span> venting at both sites is confirmed by elevated hydrogen sulphide concentrations and discharge of high-temperature fluids, reaching 270°C in the JMVFs and 317°C in the LCHF. Barite chimneys from the JMVFs are composed of barite, silica and abundant pyrite-dominated sulphide minerals that display a conspicuous concentric morphology. Raman spectroscopic analysis of the central regions of these concentric sulphide minerals points to the existence of mackinawite (FeS). Furthermore, the existence of greigite (Fe3S4) surrounding the mackinawite is suggested. This observation confirms the general conclusion of earlier experimental studies that these phases act as the metastable precursors of pyrite. In contrast, the barite chimneys of the LCHF consist mainly of pure barite with lesser amounts of sulphide minerals. The difference in the mineralogical composition between the two sites is also expressed in its sulphur isotopic composition. δ34Ssulphate values of the barite chimneys from the JMVFs are lower than δ34S of seawater sulphate (δ34S = +21‰) and δ34Ssulphide values point to a magmatic sulphur source (δ34S = 0‰). This implies that the JMHFs barite chimneys have been formed by a mixture of seawater and <span class="hlt">hydrothermal</span> fluids, similar to the origin of black smokers. In contrast to the JMVFs, the δ34Ssulphate values from the LCHF barite chimneys are higher than δ34S values for seawater sulphate, but show remarkable differences</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JGR....99.4937G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JGR....99.4937G"><span>Heat flux from black smokers on the <span class="hlt">Endeavour</span> and Cleft segments, 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>Ginster, Ursula; Mottl, Michael J.; von Herzen, Richard P.</p> <p>1994-03-01</p> <p>We have estimated the heat flux from black smoker vents on the Juan de Fuca Ridge to evaluate their importance for heat transfer from young oceanic crust. The velocity and temperature of smoker effluent were measured from the manned submersible Alvin within a few centimeters of vent orifices, using a turbine flowmeter with an attached temperature probe. Exit velocity was calculated from a simple plume model, and vent orifices were measured in photographs and video records. The estimated power output from smokers alone is 49 plus or minus 13 MW for the Plume site, Vent 1 and Vent 3 on the southern Cleft segment near 45 deg N; 364 plus or minus 73 MW for the main vent field on the <span class="hlt">Endeavour</span> Segment near 48 deg N; and 122 plus or minus 61 MW for the Tubeworm field 2 km north. The estimates for the Cleft and Tubeworm fields could be too low because of undiscovered vents. These values constitute only 4% to 14% of the total advective heat flux estimated for these vent fields from measurements in the nonbuoyant plume and of diffuse flow at the seafloor, indicating that most of the heat advected at these <span class="hlt">hydrothermal</span> vent sites is carried by diffuse rather than focused flow. Values for individual smokers vary from 0.1 to 94 MW, with an average of 6.2 MW at the <span class="hlt">Endeavour</span> field and 3.1 MW at the Cleft field. Our estimates agree well at all scales with those of Bemis et al. (1993) based on measurements made during the same dives, in some cases simultaneously, up to 50 m high in the buoyant plume. The good agreement between the two techniques implies that little diffuse flow at either high or low temperature is incorporated into the buoyant plumes generated by smokers at these sites. Velocity-temperature measurements at vents excavated by Alvin could not be modeled successfully, suggesting that vent structures may grow in equilibrium with the force of the exiting water such that orifice size is determined by volume flux. At the <span class="hlt">Endeavour</span> field the heat flux is focused by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1982/0980/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1982/0980/report.pdf"><span>Integrated model of the shallow and deep <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the East Mesa area, Imperial Valley, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Riney, T. David; Pritchett, J.W.; Rice, L.F.</p> <p>1982-01-01</p> <p>Geological, geophysical, thermal, petrophysical and hydrological data available for the East Mesa <span class="hlt">hydrothermal</span> <span class="hlt">system</span> that are pertinent to the construction of a computer model of the natural flow of heat and fluid mass within the <span class="hlt">system</span> are assembled and correlated. A conceptual model of the full <span class="hlt">system</span> is developed and a subregion selected for quantitative modeling. By invoking the .Boussinesq approximation, valid for describing the natural flow of heat and mass in a liquid <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, it is found practical to carry computer simulations far enough in time to ensure that steady-state conditions are obtained. Initial calculations for an axisymmetric model approximating the <span class="hlt">system</span> demonstrate that the vertical formation permeability of the deep East Mesa <span class="hlt">system</span> must be very low (kv ~ 0.25 to 0.5 md). Since subsurface temperature and surface heat flow data exhibit major deviations from the axisymmetric approximation, exploratory three-dimensional calculations are performed to assess the effects of various mechanisms which might operate to produce such observed asymmetries. A three-dimensional model evolves from this iterative data synthesis and computer analysis which includes a hot fluid convective source distributed along a leaky fault radiating northward from the center of the hot spot and realistic variations in the reservoir formation properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5224487','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5224487"><span>Integrated model of the shallow and deep <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> in the East Mesa area, Imperial Valley, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Riney, T.D.; Pritchett, J.W.; Rice, L.F.</p> <p>1982-01-01</p> <p>Geological, geophysical, thermal, petrophysical and hydrological data available for the East Mesa <span class="hlt">hydrothermal</span> <span class="hlt">system</span> that are pertinent to the construction of a computer model of the natural flow of heat and fluid mass within the <span class="hlt">system</span> are assembled and correlated. A conceptual model of the full <span class="hlt">system</span> is developed and a subregion selected for quantitative modeling. By invoking the Boussinesq approximation, valid for describing the natural flow of heat and mass in a liquid <span class="hlt">hydrothermal</span> <span class="hlt">system</span>, it is found practical to carry computer simulations far enough in time to ensure that steady-state conditions are obtained. Initial calculations for an axisymmetric model approximating the <span class="hlt">system</span> demonstrate that the vertical formation permeability of the deep East Mesa <span class="hlt">system</span> must be very low (k/sub v/ approx. 0.25 to 0.5 md). Since subsurface temperature and surface heat flow data exhibit major deviations from the axisymmetric approximation, exploratory three-dimensional calculations are performed to assess the effects of various mechanisms which might operate to produce such observed asymmetries. A three-dimensional model evolves from this iterative data synthesis and computer analysis which includes a hot fluid convective source distributed along a leaky fault radiating northward from the center of the hot spot and realistic variations in the reservoir formation properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.3253K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.3253K"><span>Chemical evolution of life-like <span class="hlt">system</span> under <span class="hlt">hydrothermal</span> environments: prebiotic formation, degradation, and functions regarding protein-like molecules and RNA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawamura, Kunio</p> <p></p> <p>The accumulation of biopolymers without enzymes is an essential step for the chemical evolu-tion towards a primitive life-like <span class="hlt">system</span>. Previously, we discussed the relationship between the RNA world hypothesis and the <span class="hlt">hydrothermal</span> origin of life hypothesis on the basis of the em-pirical data of RNA behaviors under the <span class="hlt">hydrothermal</span> environments examined using real-time monitoring technique for <span class="hlt">hydrothermal</span> reactions within the millisecond to second time scale. On the other hand, we have also examined the stabilities and behaviors of amino acids, pep-tides, and proteins under the <span class="hlt">hydrothermal</span> environments. These observations have shown the possibility that oligopeptides could have been accumulated under near submarine <span class="hlt">hydrother-mal</span> vent environments on primitive Earth within the relatively short time scale. However, the formation of oligopeptides under the simulated <span class="hlt">hydrothermal</span> conditions is not so effective in the absence of catalysts and condensation agents. Thus, the investigation of the roles of min-eral catalysis and condensation reagents are very important since these materials could have enhanced efficiently the formation of peptides and stabilize primitive protein-like molecules. Recently, we investigated the roles of condensation reagents for the elongation of oligopeptides in the presence of minerals. In addition, we have designed a mineral-mediated <span class="hlt">hydrothermal</span> flow reactor <span class="hlt">system</span> (MHFR), which enables monitoring <span class="hlt">hydrothermal</span> reactions in the presence of solid particles. By using MHFR, we attempted to examine naturally occurring minerals, such as apatite and quartz, for the elongation of oligopeptides at temperatures over 200 o C within 10 -30 sec. According to these data, the chemical evolution of protein-like molecules on primitive Earth will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUSMNS33A..14H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUSMNS33A..14H"><span>3D Seismic and Magnetic characterization of the Borax Lake <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> in the Alvord Desert, southeastern Oregon.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hess, S.; Bradford, J.; Lyle, M.; Routh, P.; Liberty, L.; Donaldson, P.</p> <p>2004-05-01</p> <p>As part of an interdisciplinary project aiming to study the link between the physical characteristics of <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> and biota that occupy those <span class="hlt">systems</span>, we are conducting a detailed geophysical characterization of an active <span class="hlt">hydrothermal</span> <span class="hlt">system</span>. The Borax Lake <span class="hlt">Hydrothermal</span> <span class="hlt">System</span> (BLHS), consisting of Borax Lake and the surrounding hot springs. BLHS is located near the center of the Alvord Basin in southeastern Oregon. The Alvord Basin is a north-south trending graben in the Northern Great Basin bounded by the Steens Mountains to the west and the Trout Creek Mountains to the east. We conducted a 2D seismic survey to characterize the geologic structure of the basin, a high-resolution 3D seismic survey to characterize the geologic structure of the BLHS, and a high-resolution 3D magnetic survey to characterize any lineaments in the bedrock that might control fluid flow in the BLHS. Previous results from the 2D seismic survey show a mid-basin basement high aligned approximately with the hot springs. In this study we present the results from the high-resolution 3D seismic and magnetic survey of the BLHS. We acquired the 3D seismic data using an SKS rifle and 240 channel recording <span class="hlt">system</span>. The seismic survey covers approximately 90,000 sq. m with a maximum inline offset aperture of 225 m, crossline aperture of 75 m, and 360 degree azimuthal coverage. The coincidental magnetic survey was collected using a Geometrics 858G cesium vapor magnetometer. We designed both surveys to span nearly 100 active <span class="hlt">hydrothermal</span> springs, including an approximately 50 m stepover in the trend of the surface expression of the hot springs. After preliminary processing, the 3D seismic data show continuous reflections up to 300 ms (~ 480 m). The initial interpretation of features seen in the 3D data cube include: normal faults dipping to the east and west, near-surface disturbances that are consistent with the trend of the hot springs, and significant near surface velocity anomalies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SSSci..63...62W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SSSci..63...62W"><span>Preparation of hollow silica nanospheres in O/W microemulsion <span class="hlt">system</span> by <span class="hlt">hydrothermal</span> temperature changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Dandan; Li, Xiuyan; Liu, Zuohua; Shi, Xue; Zhou, Guowei</p> <p>2017-01-01</p> <p>Hollow silica nanospheres with wrinkled or smooth surfaces were successfully fabricated through a <span class="hlt">hydrothermal</span> method. In this method, oil-in-water microemulsion (composed of cyclohexane, water, ethanol, and cetyltrimethylammonium bromide), and polyvinylpyrrolidone were utilized as template and capping agent, respectively. In such a facile synthesis, we can well realize the morphological transformation of spheres with radially oriented mesochannels to hollow structures of silica nanoparticle only by regulating the <span class="hlt">hydrothermal</span> temperature from 100 °C to 200 °C. Synthesized samples with different mesostructures were then used as supports to immobilize Candida rugosa lipase (CRL). The immobilized CRL was employed as a new biocatalyst for biodiesel production through the esterification of heptanoic acid with ethanol. The conversion ratio of heptanoic acid with ethanol catalyzed by the immobilized CRL was also evaluated. Results of this study suggest that the prepared samples have potential applications in biocatalysis.</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>Study of <span class="hlt">Hydrothermal</span> Particulate Matter from a Shallow Venting <span class="hlt">System</span>, 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> site 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('https://ntrs.nasa.gov/search.jsp?R=20020086497&hterms=water+network&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwater%2Bnetwork','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020086497&hterms=water+network&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwater%2Bnetwork"><span>Controls on Martian <span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span>: Application to Valley Network and Magnetic Anomaly Formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harrison, Keith P.; Grimm, Robert E.</p> <p>2002-01-01</p> <p>Models of <span class="hlt">hydrothermal</span> groundwater circulation can quantify limits to the role of <span class="hlt">hydrothermal</span> activity in Martian crustal processes. We present here the results of numerical simulations of convection in a porous medium due to the presence of a hot intruded magma chamber. The parameter space includes magma chamber depth, volume, aspect ratio, and host rock permeability and porosity. A primary goal of the models is the computation of surface discharge. Discharge increases approximately linearly with chamber volume, decreases weakly with depth (at low geothermal gradients), and is maximized for equant-shaped chambers. Discharge increases linearly with permeability until limited by the energy available from the intrusion. Changes in the average porosity are balanced by changes in flow velocity and therefore have little effect. Water/rock ratios of approximately 0.1, obtained by other workers from models based on the mineralogy of the Shergotty meteorite, imply minimum permeabilities of 10(exp -16) sq m2 during <span class="hlt">hydrothermal</span> alteration. If substantial vapor volumes are required for soil alteration, the permeability must exceed 10(exp -15) sq m. The principal application of our model is to test the viability of <span class="hlt">hydrothermal</span> circulation as the primary process responsible for the broad spatial correlation of Martian valley networks with magnetic anomalies. For host rock permeabilities as low as 10(exp -17) sq m and intrusion volumes as low as 50 cu km, the total discharge due to intrusions building that part of the southern highlands crust associated with magnetic anomalies spans a comparable range as the inferred discharge from the overlying valley networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.V44A..04E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.V44A..04E"><span><span class="hlt">Hydrothermal</span> <span class="hlt">Systems</span> on Kermadec Arc Volcanoes Revealed by PISCES V Submersible 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.; de Ronde, C. E.; Massoth, G. J.; Wright, I. C.; Butterfield, D. A.; Clark, M. R.; Chadwick, W. W.; Lupton, J. E.; Malahoff, A.; Rowden, A. A.; Stott, M.; Evans, L. J.; Greene, R. R.; Opatkiewicz, A.; Roe, K.</p> <p>2005-12-01</p> <p>An interdisciplinary team of scientists from New Zealand and the United States conducted seventeen dives with the PISCES V at eight Kermadec arc volcanoes (seven were the first exploration) in April and May of 2005. The dive sites were selected based on the results of water column and multibeam surveys conducted by the New Zealand research vessel Tangaroa between 1999 and 2004. Five of the sites (Monowai, Macauley, "W", Brothers and Healy) were in calderas or on young cones within calderas. Two sites were on the summits of stratovolcanoes (Rumble V and Clark) without calderas and one site was in a summit crater (Giggenbach). A planned dive site on Monowai Cone was cancelled due to safety concerns based on its history of recent volcanic activity from hydroacoustic monitoring, mass-wasting and surface observations of sulfur slicks and CO2 bubble columns made in the October 2004. <span class="hlt">Hydrothermal</span> <span class="hlt">systems</span> were found at all of the sites but they differed in the style of venting. Three factors appear to determine the character of venting on the Kermadec Arc volcanoes. First, depth exerts important boundary conditions on the style of venting because of its control of the boiling point of seawater. The sites range in depth from less than 100 m (Giggenbach) to 1800 m (Brothers caldera wall). At the shallowest depths, degassing and boiling were observed (Giggenbach Volcano at 180 m) commonly accompanied by the precipitation of elemental sulfur (340 m at the bottom of the summit crater at Macauley Cone). At greater depths such as the northwest wall of Brother's volcano, higher temperature vent fluids alter near-surface country rock and have precipitated massive sulfides on the seafloor. Second, some of the volcanoes (Monowai, Brothers and Macauley cones and Giggenbach crater) have likely had recent magmatic/eruptive activity which could result in the enhanced degassing. Finally, outcrop-scale fracturing that mimics larger-scale regional tectonic lineaments appears to focus the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4433H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4433H"><span>Imaging <span class="hlt">hydrothermal</span> <span class="hlt">systems</span> at Furnas caldera (Azores, Portugal): Insights from Audio-Magnetotelluric data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hogg, Colin; Kiyan, Duygu; Rath, Volker; Byrdina, Svetlana; Vandemeulebrouck, Jean; Silva, Catarina; Viveiros, Maria FB; Ferreira, Teresa</p> <p>2016-04-01</p> <p>The Furnas volcano is the eastern-most of the three active central volcanoes of Sao Miguel Island. The main caldera formed about 30 ka BP, followed by a younger eruption at 10-12 ka BP, which forms the steep topography of more than 200 m in the measuring area. It contains several very young eruptive centers, and a shallow caldera lake. Tectonic features of varying directions have been identified in the Caldera and its vicinity. In the northern part of the caldera, containing the fumarole field of Caldeiras das Furnas, a detailed map of surface CO2 emissions was recently made available. In 2015, a pilot survey of 13 AudioMagnetoTelluric soundings (AMT) and Electrical Resistivity Tomography (ERT) data were collected along two profiles in the eastern part of Furnas caldera in order to image the electrical conductivity of the subsurface. The data quality achieved by both techniques is extraordinary and first results indicate a general correlation between regions of elevated conductivity and the mapped surface CO2 emissions, suggesting that they may both be caused by the presence <span class="hlt">hydrothermal</span> fluids. Tensor decomposition analysis using the Groom-Bailey approach produce a generalised geo-electric strike direction, 72deg East of North, for the AMT data compared to the surface geological strike derived from the major mapped fault crossing the profiles of 105deg. An analysis of the real induction arrows at certain frequencies (at depths greater than 350 m) infer that an extended conductor at depth does not exactly correspond to the degassing structures at the surface and extends outside the area of investigation. The geometry of the most conductive regions with electrical conductivities less the