WorldWideScience

Sample records for hydrothermal systems related

  1. Dynamic behavior of Kilauea Volcano and its relation to hydrothermal systems and geothermal energy

    Science.gov (United States)

    Kauhikaua, Jim; Moore, R.B.; ,

    1993-01-01

    Exploitation of hydrothermal systems on active basaltic volcanoes poses some unique questions about the role of volcanism and hydrothermal system evolution. Volcanic activity creates and maintains hydrothermal systems while earthquakes create permeable fractures that, at least temporarily, enhance circulation. Magma and water, possibly hydrothermal water, can interact violently to produce explosive eruptions. Finally, we speculate on whether volcanic behavior can be affected by high rates of heat extraction.

  2. Relative Importance of Chemoautotrophy for Primary Production in a Light Exposed Marine Shallow Hydrothermal System.

    Science.gov (United States)

    Gomez-Saez, Gonzalo V; Pop Ristova, Petra; Sievert, Stefan M; Elvert, Marcus; Hinrichs, Kai-Uwe; Bühring, Solveig I

    2017-01-01

    The unique geochemistry of marine shallow-water hydrothermal systems promotes the establishment of diverse microbial communities with a range of metabolic pathways. In contrast to deep-sea vents, shallow-water vents not only support chemosynthesis, but also phototrophic primary production due to the availability of light. However, comprehensive studies targeting the predominant biogeochemical processes are rare, and consequently a holistic understanding of the functioning of these ecosystems is currently lacking. To this end, we combined stable isotope probing of lipid biomarkers with an analysis of the bacterial communities to investigate if chemoautotrophy, in parallel to photoautotrophy, plays an important role in autotrophic carbon fixation and to identify the key players. The study was carried out at a marine shallow-water hydrothermal system located at 5 m water depth off Dominica Island (Lesser Antilles), characterized by up to 55°C warm hydrothermal fluids that contain high amounts of dissolved Fe(2+). Analysis of the bacterial diversity revealed Anaerolineae of the Chloroflexi as the most abundant bacterial class. Furthermore, the presence of key players involved in iron cycling generally known from deep-sea hydrothermal vents (e.g., Zetaproteobacteria and Geothermobacter), supported the importance of iron-driven redox processes in this hydrothermal system. Uptake of (13)C-bicarbonate into bacterial fatty acids under light and dark conditions revealed active photo- and chemoautotrophic communities, with chemoautotrophy accounting for up to 65% of the observed autotrophic carbon fixation. Relatively increased (13)C-incorporation in the dark allowed the classification of aiC15:0, C15:0, and iC16:0 as potential lipid biomarkers for bacterial chemoautotrophy in this ecosystem. Highest total (13)C-incorporation into fatty acids took place at the sediment surface, but chemosynthesis was found to be active down to 8 cm sediment depth. In conclusion, this study

  3. Relations of ammonium minerals at several hydrothermal systems in the western U.S.

    Science.gov (United States)

    Krohn, M. Dennis; Kendall, Carol; Evans, John R.; Fries, Terry L.

    1993-08-01

    Ammonium bound to silicate and sulfate minerals has recently been located at several major hydrothermal systems in the western U.S. utilizing newly-discovered near-infrared spectral properties. Knowledge of the origin and mineralogic relations of ammonium minerals at known hydrothermal systems 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 hydrothermal systems, 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.

  4. The Lassen hydrothermal system

    Science.gov (United States)

    Ingebritsen, Steven E.; Bergfeld, Deborah; Clor, Laura; Evans, William C.

    2016-01-01

    The active Lassen hydrothermal system includes a central vapor-dominated zone or zones beneath the Lassen highlands underlain by ~240 °C high-chloride waters that discharge at lower elevations. It is the best-exposed and largest hydrothermal system in the Cascade Range, discharging 41 ± 10 kg/s of steam (~115 MW) and 23 ± 2 kg/s of high-chloride waters (~27 MW). The Lassen system accounts for a full 1/3 of the total high-temperature hydrothermal heat discharge in the U.S. Cascades (140/400 MW). Hydrothermal 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 hydrothermal system mines heat from near-plastic rock. If so, the combined areal extent of the primary heat-transfer zones is ~5 km2, the average conductive heat flux over that area is >25 W/m2, and the conductive-boundary length system or owe to various geologic events such as the eruption of Lassen Peak at 27 ka, deglaciation beginning ~18 ka, the eruptions of Chaos Crags at 1.1 ka, or the minor 1914–1917 eruption at the summit of Lassen Peak. However, there is a rich record of intermittent hydrothermal measurement over the past several decades and more-frequent measurement 2009–present. These data reveal sensitivity to climate and weather conditions, seasonal variability that owes to interaction with the shallow hydrologic system, and a transient 1.5- to twofold increase in high-chloride discharge in response to an earthquake swarm in mid-November 2014.

  5. Composite synvolcanic intrusions associated with Precambrian VMS-related hydrothermal systems

    Science.gov (United States)

    Galley, Alan G.

    2003-06-01

    Large subvolcanic intrusions are recognized within most Precambrian VMS camps. Of these, 80% are quartz diorite-tonalite-trondhjemite composite intrusions. The VMS camps spatially associated with composite intrusions account for >90% of the aggregate sulfide tonnage of all the Precambrian, intrusion-related VMS camps. These low-alumina, low-K, and high-Na composite intrusions contain early phases of quartz diorite and tonalite, followed by more voluminous trondhjemite. They have a high proportion of high silica (>74% SiO2) trondhjemite which is compositionally similar to the VMS-hosting rhyolites within the volcanic host-rock successions. The quartz-diorite and possibly tonalite phases follow tholeiitic fractionation trends whereas the trondhjemites fall within the composition field for primitive crustal melts. These transitional M-I-type primitive intrusive suites are associated with extensional regimes within oceanic-arc environments. Subvolcanic composite intrusions related to the Archean Sturgeon Lake and Noranda, and Paleoproterozoic Snow Lake VMS camps range in volume from 300 to 1,000 km3. Three have a sill morphology with strike lengths between 15 and 22 km and an average thickness between 1,500 and 2,000 m. The fourth has a gross stock-like shape. The VMS deposits are principally restricted to the volcanic strata above the strike length of the intrusions, as are areally extensive, thin exhalite units. The composite intrusions contain numerous internal phases which are commonly clustered within certain parts of the composite intrusion. These clusters underlie eruptive centers surrounded by areas of hydrothermal alteration and which contain most of the VMS deposits. Early quartz-diorite and tonalite phases appear to have intruded in rapid succession. Evidence includes gradational contacts, magma mixing and disequilibrium textures. They appear to have been emplaced as sill-dike swarms. These early phases are present as pendants and xenoliths within later

  6. Hydrothermal processes above the Yellowstone magma chamber: Large hydrothermal systems and large hydrothermal explosions

    Science.gov (United States)

    Morgan, L.A.; Shanks, W.C. Pat; Pierce, K.L.

    2009-01-01

    Hydrothermal explosions are violent and dramatic events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments from source craters that range from a few meters up to more than 2 km in diameter; associated breccia can be emplaced as much as 3 to 4 km from the largest craters. Hydrothermal explosions occur where shallow interconnected reservoirs of steam- and liquid-saturated fluids with temperatures at or near the boiling curve underlie thermal fields. Sudden reduction in confi ning pressure causes fluids to fl ash to steam, resulting in signifi cant expansion, rock fragmentation, and debris ejection. In Yellowstone, hydrothermal explosions are a potentially signifi cant hazard for visitors and facilities and can damage or even destroy thermal features. The breccia deposits and associated craters formed from hydrothermal explosions are mapped as mostly Holocene (the Mary Bay deposit is older) units throughout Yellowstone National Park (YNP) and are spatially related to within the 0.64-Ma Yellowstone caldera and along the active Norris-Mammoth tectonic corridor. In Yellowstone, at least 20 large (>100 m in diameter) hydrothermal explosion craters have been identifi ed; the scale of the individual associated events dwarfs similar features in geothermal areas elsewhere in the world. Large hydrothermal explosions in Yellowstone have occurred over the past 16 ka averaging ??1 every 700 yr; similar events are likely in the future. Our studies of large hydrothermal explosion events indicate: (1) none are directly associated with eruptive volcanic or shallow intrusive events; (2) several historical explosions have been triggered by seismic events; (3) lithic clasts and comingled matrix material that form hydrothermal explosion deposits are extensively altered, indicating that explosions occur in areas subjected to intense hydrothermal processes; (4) many lithic clasts contained in explosion breccia deposits preserve evidence of repeated fracturing

  7. Natural occurrence and stability of pyrochlore in carbonatites, related hydrothermal systems, and weathering environments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, G.R. [Australian Nuclear Science and Technology Organisation, Menai, New South Wales (Australia). Materials Div.; Mariano, A.N.

    1996-08-01

    Stoichiometric and non-stoichiometric (defect) pyrochlores crystallize during the magmatic and late magmatic-hydrothermal phases of carbonatite emplacement (T > 450--550 C, P < 2 kb). Defect pyrochlores can also form at low temperatures in laterite horizons during weathering. After crystallization, pyrochlore is subject to alteration by hydrothermal fluids (T {approximately} 550--200 C) and ground water. Alteration occurs primarily by ion exchange of low valence A-site cations together with O, F, and OH ions. The high valence cations Th and U are generally immobile; however, the authors have documented one example of hydrothermal alteration involving loss of U together with cation exchange at the B-site in samples from Mountain Pass, California. During laterite accumulation, the cation exchange rate of pyrochlore greatly exceeds the rate of matrix dissolution. The exceptional durability of pyrochlore in natural environments is related to the stability of the B-site framework cations. In carbonatites, defect pyrochlores may contain significant amounts of Si (up to 7.6 wt% SiO{sub 2}) which is negatively correlated with Nb.

  8. Tertiary tilting and dismemberment of the laramide arc and related hydrothermal systems, Sierrita Mountain, Arizona

    Science.gov (United States)

    Stavast, W.J.A.; Butler, R.P.; Seedorff, E.; Barton, M.D.; Ferguson, C.A.

    2008-01-01

    Multiple lines of evidence, including new and published geologic mapping and paleomagnetic and geobarometric determinations, demonstrate that the rocks and large porphyry copper systems 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-hydrothermal 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 systems are largely upright and dismembered by thrust faults, highlight the necessity of restoring Tertiary rotations before interpreting Laramide structural and hydrothermal features, and add to the broader understanding of pluton emplacement and evolution of porphyry copper systems. ?? 2008 Society of Economic Geologists, Inc.

  9. Dynamics of the Yellowstone hydrothermal system

    Science.gov (United States)

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-01-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal 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 hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  10. Numerical simulation of magmatic hydrothermal systems

    Science.gov (United States)

    Ingebritsen, S.E.; Geiger, S.; Hurwitz, S.; Driesner, T.

    2010-01-01

    The dynamic behavior of magmatic hydrothermal systems entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these systems depends mainly on numerical solution of coupled partial differential equations and complementary equations of state (EOS). The past 2 decades have seen steady growth of computational power and the development of numerical models that have eliminated or minimized the need for various simplifying assumptions. Considerable heuristic insight has been gained from process-oriented numerical modeling. Recent modeling efforts employing relatively complete EOS and accurate transport calculations have revealed dynamic behavior that was damped by linearized, less accurate models, including fluid property control of hydrothermal 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 hydrothermally driven deformation. Key areas for future reSearch include incorporation of accurate EOS for the complete H2O-NaCl-CO2 system, more realistic treatment of material heterogeneity in space and time, realistic description of large-scale relative permeability behavior, and intercode benchmarking comparisons. Copyright 2010 by the American Geophysical Union.

  11. Relation between ore-forming hydrothermal systems and extensional deformation in the Solea graben spreading center, Troodos ophiolite, Cyprus

    Science.gov (United States)

    Bettison-Varga, Lori; Varga, Robert J.; Schiffman, Peter

    1992-11-01

    Field relations indicate that high-temperature hydrothermal circulation and accumulation of massive sulfide deposits within the Solea graben of the Troodos ophiolite, Cyprus, followed extreme crustal attenuation. Zones of pervasive, massive epidosite strike parallel to the axis of the Solea graben and to the strike of extensional normal faults. Initial fluid flow, evidenced by preferential epidotization in weakly altered areas surrounding massively altered regions, was focused along joints, microfractures, and (now) low-angle normal-fault zones related to graben formation. Permeability within the sheeted-dike section was enhanced by brittle deformation related to extensional structures as well as through volume reduction inherent in the diabase to epidosite mineralogic phase transformations. Intrusion of high-level gabbros into epidosite zones occurred both before and after significant amagmatic tectonic extension. Structural control on epidotization suggests that intrusion of late stocks into attenuated and highly deformed crust is necessary to drive the vigorous hydrothermal circulation that produced the epidosites and ore bodies of the Solea graben. A similar sequence of events is more likely to occur in the modern oceans along ridge crests with ephemeral magmatism, especially at intermediate- to slow-spreading ridges near transform faults.

  12. Hydrothermal system of Long Valley caldera, California

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Lewis, R.E.; Olmsted, F.H.

    1978-01-01

    The geologic and hydrologic setting of the hydrothermal system are described. The geochemical and thermal characteristics of the system are presented. A mathematical model of the Long Valley caldera is analyzed. (MHR)

  13. What Defines a Separate Hydrothermal System

    Energy Technology Data Exchange (ETDEWEB)

    Lawless, J.V.; Bogie, I.; Bignall, G.

    1995-01-01

    Separate hydrothermal systems can be defined in a variety of ways. Criteria which have been applied include separation of heat source, upflow, economic resource and geophysical anomaly. Alternatively, connections have been defined by the effects of withdrawal of economically useful fluid and subsidence, effects of reinjection, changes in thermal features, or by a hydrological connection of groundwaters. It is proposed here that: ''A separate hydrothermal system is one that is fed by a separate convective upflow of fluid, at a depth above the brittle-ductile transition for the host rocks, while acknowledging that separate hydrothermal systems can be hydrologically interconnected at shallower levels''.

  14. Fault-Related Controls on Upward Hydrothermal Flow: An Integrated Geological Study of the Têt Fault System, Eastern Pyrénées (France

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    Audrey Taillefer

    2017-01-01

    Full Text Available The way faults control upward fluid flow in nonmagmatic hydrothermal systems in extensional context is still unclear. In the Eastern Pyrénées, an alignment of twenty-nine hot springs (29°C to 73°C, along the normal Têt fault, offers the opportunity to study this process. Using an integrated multiscale geological approach including mapping, remote sensing, and macro- and microscopic analyses of fault zones, we show that emergence is always located in crystalline rocks at gneiss-metasediments contacts, mostly in the Têt fault footwall. The hot springs distribution is related to high topographic reliefs, which are associated with fault throw and segmentation. In more detail, emergence localizes either (1 in brittle fault damage zones at the intersection between the Têt fault and subsidiary faults or (2 in ductile faults where dissolution cavities are observed along foliations, allowing juxtaposition of metasediments. Using these observations and 2D simple numerical simulation, we propose a hydrogeological model of upward hydrothermal flow. Meteoric fluids, infiltrated at high elevation in the fault footwall relief, get warmer at depth because of the geothermal gradient. Topography-related hydraulic gradient and buoyancy forces cause hot fluid rise along permeability anisotropies associated with lithological juxtapositions, fracture, and fault zone compositions.

  15. Peptide synthesis in early earth hydrothermal systems

    Science.gov (United States)

    Lemke, K.H.; Rosenbauer, R.J.; Bird, D.K.

    2009-01-01

    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 hydrothermal 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 hydrothermal studies, we demonstrate that peptide synthesis is favored in hydrothermal 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 hydrothermal systems will enhance peptide chain elongation. It is anticipated that the abundant hydrothermal systems on early Earth could have provided a substantial source of biomolecules required for the origin of life. Astrobiology 9, 141-146. ?? 2009 Mary Ann Liebert, Inc. 2009.

  16. Catastrophic volcanic collapse: relation to hydrothermal processes.

    Science.gov (United States)

    López, D L; Williams, S N

    1993-06-18

    Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.

  17. The potential hydrothermal systems unexplored in the Southwest Indian Ocean

    Science.gov (United States)

    Suo, Yanhui; Li, Sanzhong; Li, Xiyao; Zhang, Zhen; Ding, Dong

    2017-01-01

    Deep-sea hydrothermal 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, hydrothermal 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). Hydrothermal 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 hydrothermal 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 hydrothermal vents has been reported. Analyzing bathymetry, gravity and geochemical data, magmatism settings are favourable for the occurrence of hydrothermal systems along these two sections. An off-axial hydrothermal system 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.

  18. Hydrothermal systems in small ocean planets.

    Science.gov (United States)

    Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

    2007-12-01

    We examine means for driving hydrothermal 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 hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal 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 hydrothermal 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).

  19. Hydrothermal vents in Lake Tanganyika, East African, Rift system

    Science.gov (United States)

    Tiercelin, Jean-Jacques; Pflumio, Catherine; Castrec, Maryse; Boulégue, Jacques; Gente, Pascal; Rolet, Joël; Coussement, Christophe; Stetter, Karl O.; Huber, Robert; Buku, Sony; Mifundu, Wafula

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 °C were measured in hydrothermal 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 hydrothermal pipes. Hydrothermal fluid end members show distinctive compositions at the two sites. The Pemba end member is a NaHCO3-enriched fluid similar to the NaHCO3 thermal fluids from lakes Magadi and Bogoria in the eastern branch off the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction off 219 and 179 °C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130 °N normal-dextral faults that intersect the north- south major rift trend. The source of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza.

  20. Relations between electrical resistivity, carbon dioxide flux, and self-potential in the shallow hydrothermal system of Solfatara (Phlegrean Fields, Italy)

    Science.gov (United States)

    Byrdina, S.; Vandemeulebrouck, J.; Cardellini, C.; Legaz, A.; Camerlynck, C.; Chiodini, G.; Lebourg, T.; Gresse, M.; Bascou, P.; Motos, G.; Carrier, A.; Caliro, S.

    2014-08-01

    We present the results of an electric resistivity tomography (ERT) survey, combined with mappings of diffuse carbon dioxide flux, ground temperature and self-potential (SP) at Solfatara, the most active crater of Phlegrean Fields. Solfatara is characterized by an intense carbon dioxide degassing, fumarole activity, and ground deformation. This ensemble of methods is applied to image the hydrothermal system of Solfatara, to understand the geometry of the fluid circulation, and to define the extension of the hydrothermal plume at a high enough resolution for a quantitative modeling. ERT inversion results show Solfatara as a globally conductive structure, with resistivity in the range 1-200 Ω m. Broad negative anomaly of self-potential in the inner part of Solfatara with a minimum in the area of Bocca Grande suggests a significant downward flow of condensing liquid water. Comparison between spatial variations of resistivity and gas flux indicates that resistivity changes at depth are related to gas saturation and fluid temperature. These variations delineate two plume structures: a liquid-dominated conductive plume below Fangaia mud-pool and a gas-dominated plume below Bocca Grande fumarole. The geometry of the Fangaia liquid-saturated plume is also imaged by a high resolution 3-D resistivity model. In order to estimate the permeability, we propose a 2-D axis-symmetric numerical model coupling Richards equation for fluid flow in conditions of partial saturation with the resistivity calculation as function of saturation only. Alternatively, we apply the Dupuit equation to estimate the permeability of the shallow layer. Using these two approaches we obtain the permeability of the shallow layer below Fangaia which ranges between (2-4) × 10- 14 m2.

  1. Anhydrite precipitation in seafloor hydrothermal systems

    Science.gov (United States)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

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

  2. Starting Conditions for Hydrothermal Systems Underneath Martian Craters: Hydrocode Modeling

    Science.gov (United States)

    Pierazzo, E.; Artemieva, N. A.; Ivanov, B. A.

    2004-01-01

    Mars is the most Earth-like of the Solar System s planets, and the first place to look for any sign of present or past extraterrestrial life. Its surface shows many features indicative of the presence of surface and sub-surface water, while impact cratering and volcanism have provided temporary and local surface heat sources throughout Mars geologic history. Impact craters are widely used ubiquitous indicators for the presence of sub-surface water or ice on Mars. In particular, the presence of significant amounts of ground ice or water would cause impact-induced hydrothermal alteration at Martian impact sites. The realization that hydrothermal systems are possible sites for the origin and early evolution of life on Earth has given rise to the hypothesis that hydrothermal systems may have had the same role on Mars. Rough estimates of the heat generated in impact events have been based on scaling relations, or thermal data based on terrestrial impacts on crystalline basements. Preliminary studies also suggest that melt sheets and target uplift are equally important heat sources for the development of a hydrothermal system, while its lifetime depends on the volume and cooling rate of the heat source, as well as the permeability of the host rocks. We present initial results of two-dimensional (2D) and three-dimensional (3D) simulations of impacts on Mars aimed at constraining the initial conditions for modeling the onset and evolution of a hydrothermal system on the red planet. Simulations of the early stages of impact cratering provide an estimate of the amount of shock melting and the pressure-temperature distribution in the target caused by various impacts on the Martian surface. Modeling of the late stage of crater collapse is necessary to characterize the final thermal state of the target, including crater uplift, and distribution of the heated target material (including the melt pool) and hot ejecta around the crater.

  3. Porosity evolution in Icelandic hydrothermal systems

    Science.gov (United States)

    Thien, B.; Kosakowski, G.; Kulik, D. A.

    2014-12-01

    Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced hydrothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems, grant number CRSII2_141843/1) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. These are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. These shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. Field observations suggest that active and fossil Icelandic hydrothermal systems are built from a superposition of completely altered and completely unaltered layers. With help of 1D and 2D reactive transport models (OpenGeoSys-GEM code), we investigate the reasons for this finding, by studying the mineralogical evolution of protoliths with different initial porosities at different temperatures and pressures, different leaching water composition and gas content, and different porosity geometries (i.e. porous medium versus fractured medium). From this study, we believe that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are key factors to explain the different alteration extents observed in field studies. We also discuss how precipitation and dissolution kinetics can influence the alteration time scales.

  4. Simple model for fault-charged hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Bodvarsson, G.S.; Miller, C.W.; Benson, S.M.

    1981-06-01

    A two-dimensional transient model of fault-charged hydrothermal systems has been developed. The model can be used to analyze temperature data from fault-charged hydrothermal systems, estimate the recharge rate from the fault, and determine how long the system has been under natural development. The model can also be used for theoretical studies of the development of fault-controlled hydrothermal systems. The model has been tentatively applied to the low-temperature hydrothermal system at Susanville, California. A resonable match was obtained with the observed temperature data, and a hot water recharge rate of 9 x 10{sup -6} m{sup 3}s/m was calculated.

  5. Geophysical imaging of shallow degassing in a Yellowstone hydrothermal system

    Science.gov (United States)

    Pasquet, S.; Holbrook, W. S.; Carr, B. J.; Sims, K. W. W.

    2016-12-01

    The Yellowstone Plateau Volcanic Field, which hosts over 10,000 thermal features, is the world's largest active continental hydrothermal system, yet very little is known about the shallow "plumbing" system connecting hydrothermal reservoirs to surface features. Here we present the results of geophysical investigations of shallow hydrothermal degassing in Yellowstone. We measured electrical resistivity, compressional-wave velocity from refraction data, and shear wave velocity from surface-wave analysis to image shallow hydrothermal 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 hydrothermal systems. Finally, our results show that Poisson's ratio can effectively discriminate gas- from water-saturated zones in hydrothermal systems.

  6. Flow and permeability structure of the Beowawe, Nevada hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Faulder, D.D. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States); Johnson, S.D.; Benoit, W.R. [Oxbow Power Services, Inc., Reno, NV (United States)

    1997-05-01

    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 hydrothermal 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 hydrothermal system ranging from 500 to 1,000 D-ft, while the deeper system ranges from 200 to 400 D-ft.

  7. Analysis of the Nuevo Leon Magnetic Anomaly and its possible relation to the Cerro Prieto magmatic-hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, N.E.; Corrigan, D.J.; Wilt, M.J.

    1984-01-01

    The broad dipolar magnetic anomaly whose positive peak is centered near Ejido Nuevo Leon, some 5 km east of the Cerro Prieto I power plant, has long been suspected to have a genetic relationship to the thermal source of the Cerro Prieto geothermal system. This suspicion was reinforced after several deep geothermal wells, drilled to depths of 3-3.5 km over the anomaly, intersected an apparent dike-sill complex consisting mainly of diabase but with minor rhyodacite. A detailed fit of the observed magnetic field to a computer model indicates that the source may be approximated by a tabular block 4 x 6 km in area, 3.7 km in depth, 2.3 km thick, and dipping slightly to the north. Mafic dike chips from one well, NL-1, were analysed by means of electron microprobe analyses which showed them to contain a titanomagnetite that is paramagnetic at in situ temperature conditions. As the dike mineralogy does not account for the magnetic anomaly, the magnetic source is believed to be a deeper, magnetite-rich assemblage of peridotite-gabbro plutons. The suite of igneous rocks was probably emplaced at a shallow depth in response to crustal extension and thinning brought on by en echelon strike-slip faulting. The bottom of the magnetic source body, at an estimated depth of 6 km, is presumed to be at or near that of the Curie isotherm (575/sup 0/C) for magnetite, the principal ferromagnetic mineral in peridotiticgabbroic rocks. The geological model derived from the magnetic study is generally supported by other geophysical data. In particular, earthquake data suggest dike injection is occurring at depths of 6-11 km in an area beneath the magnetic source. Thus, it is possible that heat for the geothermal field is being maintained by continuing crustal extension and magmatic activity.

  8. Analysis of the Nuevo Leon magnetic anomaly and its possible relation to the Cerro Prieto magmatic-hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, N.E.; Wilt, M.J.; Corrigan, D.J.

    1982-10-01

    The broad dipolar magnetic anomaly whose positive peak is centered near Ejido Nuevo Leon, some 5 km east of the Cerro Prieto I Power Plant, has long been suspected to have a genetic relationship to the thermal source of the Cerro Prieto geothermal system. This suspicion was reinforced after several deep geothermal wells, drilled to depths of 3 to 3.5 km over the anomaly, intersected an apparent dike-sill complex consisting mainly of diabase but with minor rhyodacite. A detailed fit of the observed magnetic field to a computer model indicates that the source may be approximated by a tabular block 4 by 6 km in area, 3.7 km in depth, 2.3 km thick, and dipping slightly to the north. Mafic dike chips from one well, NL-1, were analyzed by means of electron microprobe analyses which showed tham to contain a titanomagnetite that is paramagnetic at in-situ temperature conditions. As the dike mineralogy does not account for the magnetic anomaly, the magnetic source is believed to be a deeper, magnetite-rich assemblage of peridotite-gabbro plutons. the suite of igneous rocks was probably passively emplaced at a shallow depth in response to crustal extension and thinning brought on by strike-slip faulting. The bottom of the magnetic source body, at an estimated depth of 6 km, is presumed to be at or near that of the Curie isotherm (575/sup 0/C) for magnetite, the principal ferromagnetic mineral in peridotitic-gabbroic rocks. The geological model derived from the magnetic study is generally supported by other geophysical data. In particular, earthquake data suggest dike injection is occurring at depths of 6 to 11 km in an area beneath the magnetic source. Thus, it is possible that heat for the geothermal field is being maintained by continuing crustal extension and magmatic activity.

  9. Reconstruction of Ancestral Hydrothermal Systems on Mount Rainier Using Hydrothermally Altered Rocks in Holocene Debris Flows and Tephras

    Science.gov (United States)

    John, D. A.; Breit, G. N.; Sisson, T. W.; Vallance, J. W.; Rye, R. O.

    2005-12-01

    geophysical data, as well as analog fossil hydrothermal systems in volcanoes elsewhere, constrain hydrothermal alteration geometry on the pre-Osceola-collapse edifice of Mount Rainier. Relatively narrow zones of acid magmatic-hydrothermal 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.

  10. Entropy Production in Convective Hydrothermal Systems

    Science.gov (United States)

    Boersing, Nele; Wellmann, Florian; Niederau, Jan

    2016-04-01

    Exploring hydrothermal reservoirs requires reliable estimates of subsurface temperatures to delineate favorable locations of boreholes. It is therefore of fundamental and practical importance to understand the thermodynamic behavior of the system in order to predict its performance with numerical studies. To this end, the thermodynamic measure of entropy production is considered as a useful abstraction tool to characterize the convective state of a system since it accounts for dissipative heat processes and gives insight into the system's average behavior in a statistical sense. Solving the underlying conservation principles of a convective hydrothermal system is sensitive to initial conditions and boundary conditions which in turn are prone to uncertain knowledge in subsurface parameters. There exist multiple numerical solutions to the mathematical description of a convective system and the prediction becomes even more challenging as the vigor of convection increases. Thus, the variety of possible modes contained in such highly non-linear problems needs to be quantified. A synthetic study is carried out to simulate fluid flow and heat transfer in a finite porous layer heated from below. Various two-dimensional models are created such that their corresponding Rayleigh numbers lie in a range from the sub-critical linear to the supercritical non-linear regime, that is purely conductive to convection-dominated systems. Entropy production is found to describe the transient evolution of convective processes fairly well and can be used to identify thermodynamic equilibrium. Additionally, varying the aspect ratio for each Rayleigh number shows that the variety of realized convection modes increases with both larger aspect ratio and higher Rayleigh number. This phenomenon is also reflected by an enlarged spread of entropy production for the realized modes. Consequently, the Rayleigh number can be correlated to the magnitude of entropy production. In cases of moderate

  11. Geophysical image of the hydrothermal system of Merapi volcano

    Science.gov (United States)

    Byrdina, S.; Friedel, S.; Vandemeulebrouck, J.; Budi-Santoso, A.; Suhari; Suryanto, W.; Rizal, M. H.; Winata, E.; Kusdaryanto

    2017-01-01

    We present an image of the hydrothermal system 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 hydrothermal system: 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 hydrothermal system (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 hydrothermal system. No evidence of the hydrothermal system 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

  12. Hydrothermal vents is Lake Tanganyika, East African Rift system

    Energy Technology Data Exchange (ETDEWEB)

    Tiercelin, J.J. [Universite de Bretagne Occidentale, Brest (France); Pflumio, C.; Castrec, M. [Universite Paris VI, Paris (France)] [and others

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal 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 hydrothermal 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 hydrothermal pipes. Hydrothermal 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 systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130{degrees}N normal-dextral faults that intersect the north-south major rift trend. The sources of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza. 21 refs., 2 figs.

  13. Combined hydrothermal liquefaction and catalytic hydrothermal gasification system and process for conversion of biomass feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.; Neuenschwander, Gary G.; Hart, Todd R.

    2017-09-12

    A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

  14. PRACTICAL AND PREDICTIVE MODELLING OF ORE DEPOSITS IN HYDROTHERMAL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    ZHAO Chong-bin; B.E.Hobbs; H.B.Muhlhaus; A.Ord

    2001-01-01

    @@ Over the past five years,we have been making efforts to develop a practical and predictive tool to explore for giant ore deposits in hydrothermal systems.Towards this goal,a significant progress has been made towards a better understanding of the basic physical and chemical processes behind ore body formation and mineralization in hydrothermal systems.

  15. PRACTICAL AND PREDICTIVE MODELLING OF ORE DEPOSITS IN HYDROTHERMAL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Chong-bin; B.E.Hobbs; H.B.Muhlhaus; A.Ord

    2001-01-01

    Over the past five years,we have been making efforts to develop a practical and predictive tool to explore for giant ore deposits in hydrothermal systems.Towards this goal,a significant progress has been made towards a better understanding of the basic physical and chemical processes behind ore body formation and mineralization in hydrothermal systems.……

  16. Evaluating the Consequences of Edifice Instability-Related Processes in Hydrothermal Ore Genesis at Composite Volcanoes

    Science.gov (United States)

    Szakacs, A.

    2009-05-01

    Composite volcanoes intrinsically evolve toward instability, which is resolved through sudden (e.g. flank/edifice failure) or gradual (e.g. volcano-basement interaction) processes. They commonly host hydrothermal systems and related ore deposits within their edifices and shallow basement. The nature and extent of the influence instability-related processes exert on these hydrothermal systems and ore genesis are as yet poorly understood. Short-term effects are basically related to sudden depressurization of the system. The key factors determining the response of the hydrothermal system are its depth and maturity, and amount of depressurization. Deep excavation will lead to evisceration of the edifice-hosted hydrothermal system, dispersion of its volatiles in the atmosphere and incorporation of solid-phase components in the resulting debris avalanche deposit (DAD). When mature, such a system may provide DAD-hosted ore deposits. The fate of the deeper, basement-hosted hydrothermal system depends on its maturity. The evolution of an immature system will be aborted as a consequence of premature depressurization-driven boiling, and no ore-grade mineralization forms. Mature systems, however, will benefit from pressure drop and induced boiling by massive deposition of pressure-sensitive ore minerals and formation of high-grade ore. Long-range effects of edifice-failure are related to increase of the meteoric input into the hydrothermal system due to the formation of a large depression and reorganization of the surface hydrologic regime. Shift from high-T vapor-dominated regime to low-T dilute hydrothermal regime is its expected outcome. The influence of gradual release of edifice instability by volcano spreading and related phenomena on the hydrothermal system has not been studied so far. Deformation induced in both edifice and basement would result in change of fluid pathways according to the shift of local stress regimes between compressional and tensional, in turn

  17. Theoretical constraints of physical and chemical properties of hydrothermal fluids on variations in chemolithotrophic microbial communities in seafloor hydrothermal systems

    Science.gov (United States)

    Nakamura, Kentaro; Takai, Ken

    2014-12-01

    In the past few decades, chemosynthetic ecosystems at deep-sea hydrothermal 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 hydrothermal fluids and ambient seawater. The chemical and isotope compositions of the hydrothermal 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, hydrothermal fluids, and geological background in deep-sea hydrothermal systems. We estimated the metabolic energy potentially available for productivity by chemolithotrophic microorganisms at various hydrothermal vent fields. We used a geochemical model based on hydrothermal fluid chemistry data compiled from 89 globally distributed hydrothermal vent sites. The model estimates were compared to the observed variability in extant microbial communities in seafloor hydrothermal environments. Our calculations clearly show that representative chemolithotrophic metabolisms (e.g., thiotrophic, hydrogenotrophic, and methanotrophic) respond differently to geological and geochemical variations in the hydrothermal systems. Nearly all of the deep-sea hydrothermal systems provide abundant energy for organisms with aerobic thiotrophic metabolisms; observed variations in the H2S concentrations among the hydrothermal 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 hydrothermal environments. In contrast, variations in H2 concentrations in hydrothermal fluids significantly impact organisms with aerobic and anaerobic hydrogenotrophic metabolisms

  18. Fractionation of Boron Isotopes in Icelandic Hydrothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, J.K.; Palmer, M.R.

    1995-01-01

    Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive {delta}{sup 11}B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive {delta}{sup 11}B than the high temperature systems, 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 systems.

  19. Microbiological production and ecological flux of northwestern subduction hydrothermal systems

    Science.gov (United States)

    Sunamura, M.; Okamura, K.; Noguchi, T.; Yamamoto, H.; Fukuba, T.; Yanagawa, K.

    2012-12-01

    Deep-sea hydrothermal system is one of the most important sources for heat and chemical flux from the oceanic crust to the global ocean. The rich biological community around the hydrothermal vent shows chemolithoautotrophic microbial production are important in deep sea ecosystems. More than 99% of microbiological available chemical components in hydrothermal vent fluid, e.g. sulfide, methane, hydrogen, Fe2+, and Mn2+, is released into surrounding seawater to construct hydrothermal plume, suggesting that the chemolithoautotrophic-microbial primary production in the hydrothermal plume is huge and important in the whole hydrothermal ecosystems. To understand the impact of hydrothermal plume to a microbial ecosystem and a connectivity with zooplankton, we targeted and investigated a total of 16 hydrothermal 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. Hydrothermal fluids in the subduction system are rich in sulfide. The hydrothermal 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 hydrothermal systems 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 hydrothermal 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

  20. Thermodynamics of Organic Compound Alteration in Hydrothermal Systems

    Science.gov (United States)

    Shock, E. L.

    2005-12-01

    Organic compounds enter hydrothermal systems through infiltrating surface waters, zones of microbial productivity in the subsurface, extracts of organic matter in surrounding host rocks, and abiotic synthesis. Owing to variations in pH, oxidation state, composition, temperature, and pressure throughout the changing pathways of fluid migration over the duration of the system, organic compounds from all of these sources are introduced to conditions where their relative stabilities and reactivities can be dramatically transformed. If those transformations were predictable, then the extent to which organic alteration reactions have occurred could be used to reveal flowpaths and histories of hydrothermal systems. Speciation and mass transfer calculations permit some insight into the underlying thermodynamic driving forces that result in organic compound alteration. As an example, the speciation of many geochemist's canonical organic matter: CH2O depends strongly on oxidation state, temperature, and total concentration of dissolved organic matter. Calculations show that at oxidation states buffered by iron-bearing mineral assemblages, organic acids dominate the speciation of CH2O throughout hydrothermal systems, with acetic acid (itself equivalent to 2 CH2O by bulk composition) and propanoic acid generally the most abundant compounds. However, at more reduced conditions, which may prevail in organic-rich iron-poor sediments, the drive is to form ketones and especially alcohols at the expense of organic acids. The distribution of organic carbon among the various members of these compound classes is strongly dependent on the total concentration of dissolved organic matter. As an example, at a bulk concentration equivalent to average dissolved organic matter in seawater (45μm), the dominant alcohols at 100°C are small compounds like ethanol and 1-propanol. In contrast, at a higher bulk concentration of 500μm, there is a drive to shift large percentages of dissolved

  1. Monitoring the hydrothermal system in Long Valley caldera, California

    Science.gov (United States)

    Farrar, C.D.; Sorey, M.L.

    1985-01-01

    An ongoing program to monitor the hydrothermal system in Long Valley for changes caused by volcanic or tectonic processes has produced considerable data on the water chemistry and discharge of springs and fluid temperatures and pressures in wells. Chemical and isotopic data collected under this program have greatly expanded the knowledge of chemical variability both in space and time. Although no chemical or isotopic changes in hot spring waters can be attributed directly to volcanic or tectonic processes, changes in hot spring chemistry that have been recorded probably relate to interactions between and variations in the quantity of liquid and gas discharged. Stable carbon isotope data are consistent with a carbon source either perform the mantle or from metamorphosed carbonate rocks. Continuous and periodic measurements of hot spring discharge at several sites show significant co seismic and a seismic changes since 1980.

  2. COVIS Detects Interconnections Between Atmospheric, Oceanic and Geologic systems at a Deep Sea Hydrothermal Vent

    Science.gov (United States)

    Bemis, K. G.; Xu, G.; Lee, R.

    2015-12-01

    COVIS (Cabled Observatory Vent Imaging Sonar) is an innovative sonar system designed to quantitatively monitor focused and diffuse flows from deep-sea hydrothermal vent clusters. From 9/2010 to 9/2015, COVIS was connected to the NEPTUNE observatory at Grotto vent in the Main Endeavour 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 hydrothermal plume mixing with the ambient seawater increases with the magnitude of ocean currents. Such current-driven entrainment links the dynamics of a deep-sea hydrothermal 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 hydrothermal 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 hydrothermal system with geological processes. These findings demonstrate the intimate interconnections of seafloor hydrothermal systems 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 hydrothermal

  3. Evolutionary strategies of cells and viruses in deep-sea hydrothermal systems revealed through comparative metagenomics

    Science.gov (United States)

    Anderson, R.; Sogin, M. L.; Baross, J. A.

    2013-12-01

    The deep-sea hydrothermal vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these systems must also withstand these environmental extremes, and a high proportion of viruses in these systems are lysogenic. Comparative analysis of a cellular and viral metagenome from a diffuse flow hydrothermal vent has provided insights into the evolutionary strategies of both cells and viruses in hydrothermal systems. 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 hydrothermal vent viral gene pool is relatively enriched in genes related to energy metabolism, a feature that is unique to the hydrothermal 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.

  4. Inversion Approach For Thermal Data From A Convecting Hydrothermal System

    Energy Technology Data Exchange (ETDEWEB)

    Kasameyer, P.; Younker, L.; Hanson, J.

    1985-01-01

    Hydrothermal systems are often studied by collecting thermal gradient data and temperature depth curves. These data contain important information about the flow field, the evolution of the hydrothermal system, and the location and nature of the ultimate heat sources. Thermal data are conventionally interpreted by the ''forward'' method; the thermal field is calculated based on selected initial conditions and boundary conditions such as temperature and permeability distributions. If the calculated thermal field matches the data, the chosen conditions are inferred to be possibly correct. Because many sets of initial conditions may produce similar thermal fields, users of the ''forward'' method may inadvertently miss the correct set of initial conditions. Analytical methods for ''inverting'' data also allow the determination of all the possible solutions consistent with the definition of the problem. In this paper we suggest an approach for inverting thermal data from a hydrothermal system, and compare it to the more conventional approach. We illustrate the difference in the methods by comparing their application to the Salton Sea Geothermal Field by Lau (1980a) and Kasameyer, et al. (1984). In this particular example, the inverse method was used to draw conclusions about the age and total rate of fluid flow into the hydrothermal system.

  5. Early Archaean sedimentary basins: depositional environment and hydrothermal systems :

    NARCIS (Netherlands)

    Vries, Sjoukje Tsjitske de

    2004-01-01

    The topic of this thesis is the Early Archaean environment and hydrothermal systems in the Barberton Greenstone Belt (BGB) in South Africa, and the Coppin Gap Greenstone Belt (CGGB) in the Pilbara, Australia. Focus within these greenstone belts is on the ~3.45-3.42 Ga Buck Ridge volcano-sedimentary

  6. Complexation of Si in Hydrothermal Systems

    Institute of Scientific and Technical Information of China (English)

    樊文苓; 王声远; 田弋夫; 陈紫新

    2001-01-01

    The Au-SiO2 and Sn-SiO2 complexes have been experimentally calibrated at varying temperature, silica concentration and pH:Au+ + H3SiO4-=AuH3SiO4 lgK = - 1. 65436 + 9611.21/TSn4 + + 4H3SiO4-=Sn(H3SiO4)4 lgK200℃ = 42.73Compared with Au-Cl, Au-HS and Sn-OH complexes, AuH3SiO4 and Sn(H3SiO4)4 complexes can be recognized as the dominant transport forms in Si-bearing solutions under pH and Eh con ditions of general interest. The decrease of SiO2 concentration and oxygen fugacity would re verse the direction of dissolution-complexing reactions, resulting in the precipitation of gold and silica, as well as cassiterite and silica. This study illustrates the significance of SiO2-complexa tion in hydrothermal solutions for gold, tin and other metallizations.

  7. Chemistry of a serpentinization-controlled hydrothermal system at the Lost City hydrothermal vent field

    Science.gov (United States)

    Ludwig, K. A.; Kelley, D. S.; Butterfield, D. A.; Nelson, B. K.; Karson, J. A.

    2003-12-01

    The Lost City Hydrothermal Field (LCHF), at 30° N near the Mid-Atlantic Ridge, is an off-axis, low temperature, high-pH, ultramafic-hosted vent system. Within the field, carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the vent structures and fluids at the LCHF is controlled by reactions between seawater and ultramafic rocks beneath the Atlantis massif. Mixing of warm alkaline vent fluids with seawater causes precipitation of calcium carbonate and growth of the edifaces, which range from tall, graceful pinnacles to fragile flanges and colloform deposits. Geochemical and petrological analyses of the carbonate rocks reveal distinct differences between the active and extinct structures. Actively venting chimneys and flanges are extremely porous, friable formations composed predominantly of aragonite and brucite. These structures provide important niches for well-developed microbial communities that thrive on and within the chimney walls. Some of the active chimneys may also contain the mineral ikaite, an unstable, hydrated form of calcium carbonate. TIMS and ICP-MS analyses of the carbonate chimneys show that the most active chimneys have low Sr isotope values and that they are low in trace metals (e.g., Mn, Ti, Pb). Active structures emit high-pH, low-Mg fluids at 40-90° C. The fluids also have low Sr values, indicating circulation of hydrothermal solutions through the serpentinite bedrock beneath the field. In contrast to the active structures, extinct chimneys are less porous, are well lithified, and they are composed predominantly of calcite that yields Sr isotopes near seawater values. Prolonged lower temperature seawater-hydrothermal fluid interaction within the chimneys results in the conversion of aragonite to calcite and in the enrichment of some trace metals (e.g., Mn, Ti, Co, Zn). It also promotes the incorporation of foraminifera within the outer, cemented walls of the carbonate

  8. Catalytic Diversity in Alkaline Hydrothermal Vent Systems on Ocean Worlds

    Science.gov (United States)

    Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik

    2016-10-01

    Hydrothermal systems formed by serpentinization can create moderate-temperature, alkaline systems 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 hydrothermal vents (Russell et al., 2014). Hydrothermal 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 systems on ocean worlds may lead to hydrothermal precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent systems.Therefore, further understanding on the electroactive roles of various organic species within hydrothermal 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

  9. Molecular evidence for abiotic sulfurization of dissolved organic matter in marine shallow hydrothermal systems

    Science.gov (United States)

    Gomez-Saez, Gonzalo V.; Niggemann, Jutta; Dittmar, Thorsten; Pohlabeln, Anika M.; Lang, Susan Q.; Noowong, Ann; Pichler, Thomas; Wörmer, Lars; Bühring, Solveig I.

    2016-10-01

    Shallow submarine hydrothermal systems are extreme environments with strong redox gradients at the interface of hot, reduced fluids and cold, oxygenated seawater. Hydrothermal 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 hydrothermal systems 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 hydrothermal systems 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, hydrothermal fluids from Milos were mainly fed by recirculating seawater. The hydrothermal 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 systems, DOS from hydrothermal fluids had on average lower O/C ratios (0.26-0.34) than surrounding surface seawater DOS (0.45-0.52), suggesting shallow hydrothermal systems 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

  10. The hydrothermal system in southern Grass Valley, Pershing County, Nevada

    Science.gov (United States)

    Welch, Alan H.; Sorey, M.L.; Olmsted, F.H.

    1981-01-01

    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 hydrothermal flow system 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 system. (USGS)

  11. Hydrothermal system in Southern Grass Valley, Pershing County, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Welch, A.H.; Sorey, M.L.; Olmsted, F.H.

    1981-01-01

    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 hydrothermal flow system 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 system.

  12. Sourcing hydrocarbons in CO2-rich in hydrothermal systems

    OpenAIRE

    Fiebig, J; F. Tassi; D'Alessandro, W.; A. B. Woodland

    2009-01-01

    Methane (CH4) emanating from a continental volcanichydrothermal system in Nisyros, Greece, is processed through the abiogenic reduction of mantle- and marine limestonederived CO2 [1]. Evidence for the occurrence of abiogenic hydrothermal reduction of CO2 is from the chemical and carbon isotopic equilibrium patterns. We have further characterized this abiogenic methane (C1) source for the concentrations of ethane (C2) and propane (C3), as well as for the hydrogen isotop...

  13. Integration of hydrothermal-energy economics: related quantitative studies

    Energy Technology Data Exchange (ETDEWEB)

    1982-08-01

    A comparison of ten models for computing the cost of hydrothermal energy is presented. This comparison involved a detailed examination of a number of technical and economic parameters of the various quantitative models with the objective of identifying the most important parameters in the context of accurate estimates of cost of hydrothermal energy. Important features of various models, such as focus of study, applications, marked sectors covered, methodology, input data requirements, and output are compared in the document. A detailed sensitivity analysis of all the important engineering and economic parameters is carried out to determine the effect of non-consideration of individual parameters.

  14. Drilling of Submarine Shallow-water Hydrothermal Systems in Volcanic Arcs of the Tyrrhenian Sea, Italy

    Science.gov (United States)

    Petersen, S.; Augustin, N.; de Benedetti, A.; Esposito, A.; Gaertner, A.; Gemmell, B.; Gibson, H.; He, G.; Huegler, M.; Kleeberg, R.; Kuever, J.; Kummer, N. A.; Lackschewitz, K.; Lappe, F.; Monecke, T.; Perrin, K.; Peters, M.; Sharpe, R.; Simpson, K.; Smith, D.; Wan, B.

    2007-12-01

    Seafloor hydrothermal systems related to volcanic arcs are known from several localities in the Tyrrhenian Sea in water depths ranging from 650 m (Palinuro Seamount) to less than 50 m (Panarea). At Palinuro Seamount 13 holes (Metal enrichment at the top of the deposit is evident in some cores with polymetallic (Zn, Pb, Ag) sulfides overlying more massive and dense pyritic ore. The massive sulfide mineralization at Palinuro Seamount contains a number of unusual minerals, including enargite, tennantite, luzonite, and Ag-sulfosalts, that are not commonly encountered in mid-ocean ridge massive sulfides. In analogy to epithermal deposits forming on land, the occurrence of these minerals suggests a high sulfidation state of the hydrothermal fluids during deposition implying that the mineralizing fluids were acidic and oxidizing rather than near-neutral and reducing as those forming typical base metal rich massive sulfides along mid-ocean ridges. Oxidizing conditions during sulfide deposition can probably be related to the presence of magmatic volatiles in the mineralizing fluids that may be derived from a degassing magma chamber. Elevated temperatures within sediment cores and TV-grab stations (up to 60°C) indicate present day hydrothermal fluid flow. This is also indicated by the presence of small tube-worm bushes present on top the sediment. A number of drill holes were placed around the known phreatic gas-rich vents of Panarea and recovered intense clay-alteration in some holes as well as abundant massive anhydrite/gypsum with only trace sulfides along a structural depression suggesting the presence of an anhydrite seal to a larger hydrothermal system at depth. The aim of this study is to understand the role that magmatic volatiles and phase separation play in the formation of these precious and trace element-rich shallow water (hydrothermal systems in the volcanic arcs of the Tyrrhenian Sea.

  15. Hydrothermal REE and Zr Ore Forming Processes in Peralkaline Granitic Systems

    Science.gov (United States)

    Gysi, A. P.

    2015-12-01

    Anorogenic peralkaline igneous systems display extreme enrichment of REE and Zr with a hydrothermal 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 systems, peralkaline systems are poorly understood and hydrothermal 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 hydrothermal 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 hydrothermal 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 hydrothermal metal mobilization in peralkaline granitic systems is the formation of a fluid-buffered subsystem providing the acids and ligands required for REE and Zr mobilization.

  16. Microbial Geochemistry in Shallow-Sea Hydrothermal Systems

    Science.gov (United States)

    Amend, J. P.; Pichler, T.

    2006-12-01

    Shallow-sea hydrothermal systems are far more ubiquitous than generally recognized. Approximately 50-60 systems are currently known, occurring world-wide in areas of high heat flow, such as, volcanic island arcs, near-surface mid-ocean ridges, and intraplate oceanic volcanoes. In contrast to deep-sea systems, shallow- sea vent fluids generally include a meteoric component, they experience phase separation near the sediment- water interface, and they discharge into the photic zone (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 reactions. In contrast to their deep-sea counterparts, shallow-sea hydrothermal systems are often characterized by high arsenic concentrations of more than 500-times seawater levels. The arsenic, generally present as arsenite (As^{III}) in the vent fluid, feeds local biogeochemical arsenic cycles. Thus, shallow sites are excellent hunting grounds for novel extremophiles that may gain metabolic energy by catalyzing arsenic redox reactions. Particularly the Ambitle site, where hydrothermal fluids contain up to 1,000 μg/L arsenite, has proven to be exceptional. There, the arsenic has a wide-ranging impact on micro-, meio-, and

  17. Fracture distribution and porosity in a fault-bound hydrothermal system (Grimsel Pass, Swiss Alps)

    Science.gov (United States)

    Egli, Daniel; Küng, Sulamith; Baumann, Rahel; Berger, Alfons; Baron, Ludovic; Herwegh, Marco

    2017-04-01

    The spatial distribution, orientation and continuity of brittle and ductile structures strongly control fluid pathways in a rock mass by joining existing pores and creating new pore space (fractures, joints) but can also act as seals to fluid flow (e.g. ductile shear zones, clay-rich fault gouges). In long-lived hydrothermal systems, permeability and the related fluid flow paths are therefore dynamic in space and time. Understanding the evolution and behaviour of naturally porous and permeable rock masses is critical for the successful exploration and sustainable exploitation of hydrothermal systems and can advance methods for planning and implementation of enhanced geothermal systems. This study focuses on an active fault-bound hydrothermal system in the crystalline basement of the Aar Massif (hydrothermal field Grimsel Pass, Swiss Alps) that has been exhumed from few kilometres depth and which documents at least 3 Ma of hydrothermal activity. The explored rock unit of the Aar massif is part of the External Crystalline Massifs that hosts a multitude of thermal springs on its southern border in the Swiss Rhône valley and furthermore represents the exhumed equivalent of potentially exploitable geothermal reservoirs in the deep crystalline subsurface of the northern Alpine foreland basin. This study combines structural data collected from a 125 m long drillhole across the hydrothermal zone, the corresponding drill core and surface mapping. Different methods are applied to estimate the porosity and the structural evolution with regard to porosity, permeability and fracture distribution. Analyses are carried out from the micrometre to decametre scale with main focus on the flow path evolution with time. This includes a large variety of porosity-types including fracture-porosity with up to cm-sized aperture down to grain-scale porosity. Main rock types are granitoid host rocks, mylonites, paleo-breccia and recent breccias. The porosity of the host rock as well as the

  18. Splicing growth of zeolite 4A in hydrothermal system

    Institute of Scientific and Technical Information of China (English)

    李酽; 汪信; 杨绪杰; 张术根

    2002-01-01

    The morphology evolution of zeolite 4A in hydrothermal system was studied via XRD, TEM and electron diffractometry. A phenomenon of aggregation of nano-crystals of zeolite 4A exists in the crystallization process, and microcrystals are derived from nano-crystal aggregating directly. The splicing growth model of zeolite 4A is described as: 1)an induction period which exists at the beginning of crystallization, 2)followed by many nano-meter crystals initiating immediately, and 3)the nanocrystals congregated as slices and spliced with each other to form a larger crystal.

  19. Hydrothermal model of the Momotombo geothermal system, Nicaragua

    Energy Technology Data Exchange (ETDEWEB)

    Verma, M.P.; Martinez, E.; Sanchez, M.; Miranda, K.; Gerardo, J.Y.; Araguas, L.

    1996-01-24

    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 hydrothermal model of the geothermal system. The chemical and stable isotopic data (δ18O 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+, K+ and Mg2+ 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.

  20. The Muruntau gold deposit (Uzbekistan – A unique ancient hydrothermal system in the southern Tien Shan

    Directory of Open Access Journals (Sweden)

    Ulf Kempe

    2016-05-01

    Full Text Available The Muruntau gold deposit in the Central Kyzylkum, Uzbekistan is one of the largest single gold deposits worldwide. Data available from the literature are reviewed with the aim to (1 integrate the present knowledge on this unique deposit from Russian and English literature; (2 show the considerable progress made in the understanding of the genesis of the Muruntau deposit during the last decades; and (3 point to problems still open for future research. Deposit formation occurred through a multi-stage process involving sedimentation, regional metamorphism including thrusting, magmatism with formation of hornfels aureoles and several stages of hydrothermal activity. According to recent knowledge, synsedimentary or pure metamorphic formation of gold mineralization seems unlikely. The role of granite magmatism occurring roughly within the same time interval as the main hydrothermal gold precipitation remains uncertain. There are no signs of interaction of matter between the magma(s and the hydrothermal system(s. On the other hand, there was an intense, high-temperature (above 400 °C fluid – wall rock interaction resulting in the formation of gold-bearing, cone-like stockworks with veins, veinlets and gold-bearing metasomatites. Several chemical and isotope indicators hint at an involvement of lower-crustal or mantle-related sources as well as of surface waters in ore formation. Deposit formation through brecciation involving explosion, hydrothermal or tectonic breccias might explain these data. Further investigations on breccia formation as well as on the exact timing of relevant sedimentary, metamorphic, magmatic and hydrothermal events are recommended.

  1. The Muruntau gold deposit (Uzbekistan) e A unique ancient hydrothermal system in the southern Tien Shan

    Institute of Scientific and Technical Information of China (English)

    Ulf Kempe; Torsten Graupner; Reimar Seltmann; Hugo de Boorder; Alla Dolgopolova

    2016-01-01

    The Muruntau gold deposit in the Central Kyzylkum, Uzbekistan is one of the largest single gold deposits worldwide. Data available from the literature are reviewed with the aim to (1) integrate the present knowledge on this unique deposit from Russian and English literature; (2) show the considerable progress made in the understanding of the genesis of the Muruntau deposit during the last decades;and (3) point to problems still open for future research. Deposit formation occurred through a multi-stage process involving sedimentation, regional metamorphism including thrusting, magmatism with for-mation of hornfels aureoles and several stages of hydrothermal activity. According to recent knowledge, synsedimentary or pure metamorphic formation of gold mineralization seems unlikely. The role of granite magmatism occurring roughly within the same time interval as the main hydrothermal gold precipitation remains uncertain. There are no signs of interaction of matter between the magma(s) and the hydrothermal system(s). On the other hand, there was an intense, high-temperature (above 400 ?C) fluid e wall rock interaction resulting in the formation of gold-bearing, cone-like stockworks with veins, veinlets and gold-bearing metasomatites. Several chemical and isotope indicators hint at an involvement of lower-crustal or mantle-related sources as well as of surface waters in ore formation. Deposit for-mation through brecciation involving explosion, hydrothermal or tectonic breccias might explain these data. Further investigations on breccia formation as well as on the exact timing of relevant sedimentary, metamorphic, magmatic and hydrothermal events are recommended.

  2. Hydrothermal precious-metal deposits related to graben-calderas of the Sierra Madre Occidental

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Labarthe-Hernandez, G.; Nieto-Obregon, J.; Tristan-Gonzalez, M.; Gonzalez-Partida, E.

    2007-05-01

    The Sierra Madre Occidental (SMO) covers the NW portion of Mexico and it is the host for several important precious metal mine operations, such as Tayoltita, Cienega, Topia, Fresnillo, Zacatecas, Guanajuato and Bolaños, just to mention a few. The southern part of the Basin and Range extension affected also NW Mexico and formed NW- to NE-trending normal faults that bound many large grabens, which are particularly long and deep in the southern SMO. Both graben formation and mid-Tertiary silicic volcanic activity coincided in space and time, particularly for the 38-23 Ma period, the Ignimbrite Flare-up event, but this activity dates back to Eocene and was as young as Miocene. This volcanism included large rhyolitic domes, too. At the southern SMO, the vents of this silicic volcanism are related to graben's master faults and we have named them graben-calderas. Evidences include large pyroclastic dikes and post-ignimbrite aligned rhyolitic domes and lava dikes. All these features were found along the graben-caldera walls or on the graben's shoulders. Some of these vents are related to gold and silver hydrothermal mineralization. In most cases a paleo-lake filled the graben-caldera for a period of time, either during the ignimbrite emplacement or after it. Some of the graben-caldera ignimbrites were deposited in subaqueous environments and post-ignimbrite rhyolitic domes and dikes were intruded in non-consolidated water-saturated tuffs or sedimentary deposits. This lacustrine environment provided the necessary water for the hydrothermal system. The combination of all these factors in space and time, grabens+volcanism+water, resulted in the development of precious-metal hydrothermal ore deposits. Bolaños mine in the Bolaños graben represent our case-study, but we have confirmed the same tectono-volcanic-lake relationship at other mine-districts along the SMO. We conclude that locating the fissural vents of the silicic ignimbrites by means of just geologic mapping is be

  3. Geochemical Energy for Catabolism and Anabolism in Hydrothermal Systems

    Science.gov (United States)

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

    2008-12-01

    Chemically reduced deep-sea vent fluids mixed with oxidized seawater can generate redox disequilibria that serve as energy sources for chemolithoautotrophic (catabolism) and biomass synthesis (anabolism) reactions. Numerical models can be used to evaluate Gibbs energies of such processes on the early Earth and in present-day systems. Here, geochemical data from compositionally diverse vent fluids (Lost City, Rainbow, Logatchev, TAG, 21 °N EPR) are combined with several seawater chemistries to yield a wide range of mixed hydrothermal solutions; this is the starting point for our thermodynamic calculations. In ultramafic-hosted hydrothermal systems, such as Rainbow or Lost City, aerobic chemolithotrophic catabolisms (oxidation of H2, FeII, CH4) are the most energy-yielding at low temperatures (catabolic reaction energetics can then be used to put constraints on the amount of primary biomass production. Under putative early Earth conditions, for example, the net chemoautotrophic synthesis of cellular building blocks is thermodynamically most favorable at moderate temperatures (~50°C), where the energy contributions from HCO3- and H+ in cool seawater coupled to the reducing power in hot vent fluid are optimized. At these conditions, and counter to conventional wisdom, the synthesis of amino acids may even yield small amounts of energy.

  4. The hydrothermal system in central Twin Falls County, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, R.E.; Young, H.W.

    1989-01-01

    This report describes the results of a study to define the areal extent and thickness of the hydrothermal reservoir in Twin Falls County and to propose a generalized conceptual model of the system. 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 hydrothermal system 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hardee, H.C.

    1980-09-01

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

  6. Hydrothermal Processes in the Solar System:A Review

    Institute of Scientific and Technical Information of China (English)

    Franco PIRAJNO; Martin J. Van KRANENDONK; Long XIAO

    2008-01-01

    最近美国航空与空间计划署(NASA)开展的卡西尼-惠更斯外空探测计划发现,在直径为500 km的卫星--土卫二上存在水冰和间隙泉的喷发活动.这一现象和在火星上工作的"机遇号"和"勇气号"漫游车所发现的液态水一起,证明了除地球以外的其他星球上过去和现在都存在水,其中的一些星体还有火山活动的证据,这意味着这些星球上可能存在过热液活动地质过程.讨论了火星、木卫二和土卫二可能存在的热液系统类型.这些热液系统类型是根据地球上的构造背景进行相似性研究后得出的,例如海底、火山和裂谷系统.将东非裂谷和贝加尔湖裂谷系统与火星Tharsis高原上巨大的水手大峡谷进行了对比,这些地区都是由地幔柱作用下构造-热液活动导致的地壳抬升、火山和裂谷作用.在火星上,地下冰或低温层会在火山活动和(或)小行星或彗星撞击作用下溶解而形成热液对流.%Recent images from the NASA Cassini-Huygens mission to the outer planets have shown evidence of water ice and gey ser-like jets on Enceladus, a Saturnian moon, only about 500 km across. This, together with the data provided by numerous mis sions to Mars, including the Spirit and Opportunity rovers, are evidence that liquid water is, and was, present on planetary bodies other than the Earth in the solar system. Some of these bodies also contain evidence of volcanism, signifying that hydrothermal processes are, or may have been, active in their geological history. In this paper, we speculate on the types of hydrothermal sys tems that could have been and/or may be present on Mars, Europa (a moon of Jupiter) and Enceladus. These hydrothermal sys tems are modelled on terrestrial analogues, such as those on the seafloor, volcanic edifices, and in rift structures. Analogies are proposed between the East African Rift System and the Baikal Rift System with the Tharsis regi on of Mars, including the

  7. Resistivity structure and geochemistry of the Jigokudani Valley hydrothermal system, Mt. Tateyama, Japan

    Science.gov (United States)

    Seki, Kaori; Kanda, Wataru; Tanbo, Toshiya; Ohba, Takeshi; Ogawa, Yasuo; Takakura, Shinichi; Nogami, Kenji; Ushioda, Masashi; Suzuki, Atsushi; Saito, Zenshiro; Matsunaga, Yasuo

    2016-10-01

    This study clarifies the hydrothermal system 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 hydrothermal system. The three-dimensional (3D) resistivity structure of the hydrothermal system 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 hydrothermal system includes a two-phase zone of vapor-liquid. A comparison of the resistivity structure and the geochemically inferred structure suggests that a hydrothermal 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 hydrothermal system of Jigokudani Valley exhibits a number of factors that could trigger a future phreatic eruption.

  8. Tracing Origin of sulfur in hydrothermal system of Eastern Taiwan

    Science.gov (United States)

    Hsu, Hsiao-Yuan; You, Chen-Feng; Chung, Chuan-Hsiung; Aggarwal, Suresh Kumar

    2016-04-01

    Multiple sulfur isotope results and sulfate concentrations are reported for different hydrothermal system 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 hydrothermal system 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 hydrothermal system 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 system. 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

  9. Soil-plant-microbial relations in hydrothermally altered soils of Northern California

    Science.gov (United States)

    Blecker, S.W.; Stillings, L.L.; DeCrappeo, N.M.; Ippolito, J.A.

    2014-01-01

    Soils developed on relict hydrothermally altered soils throughout the Western USA present unique opportunities to study the role of geology on above and belowground biotic activity and composition. Soil and vegetation samples were taken at three unaltered andesite and three hydrothermally altered (acid-sulfate) sites located in and around Lassen VolcanicNational Park in northeastern California. In addition, three different types of disturbed areas (clearcut, thinned, and pipeline) were sampled in acid-sulfate altered sites. Soils were sampled (0–15 cm) in mid-summer 2010 from both under-canopy and between-canopy areas within each of the sites. Soils were analyzed for numerous physical and chemical properties along with soil enzyme assays, C and N mineralization potential, microbial biomass-C and C-substrate utilization. Field vegetation measurements consisted of canopy cover by life form (tree, shrub, forb, and grass), tree and shrub density, and above-ground net primary productivity of the understory. Overall, parameters at the clearcut sites were more similar to the unaltered sites, while parameters at the thinned and pipeline sites were more similar to the altered sites. We employed principal components analysis (PCA) to develop two soil quality indices (SQI) to help quantify the differences among the sites: one based on the correlation between soil parameters and canopy cover, and the second based on six sub-indices. Soil quality indices developed in these systems could provide a means for monitoring and identifying key relations between the vegetation, soils, and microorganisms.

  10. Seismic tomography and dynamics of geothermal and natural hydrothermal systems in the south of Bandung, Indonesia

    Science.gov (United States)

    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

    2015-04-01

    The structure and the dynamics of geothermal reservoirs and hydrothermal systems 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 hydrothermal 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 hydrothermal systems. We aim at searching possible structural and dynamical links between different hydrothermal systems. In addition, we discuss possible dynamical implications of this complex volcanic systems 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.

  11. Surficial extent and conceptual model of hydrothermal system at Mount Rainier, Washington

    Science.gov (United States)

    Frank, David

    1995-04-01

    A once massive hydrothermal system was disgorged from the summit of Mount Rainier in a highly destructive manner about 5000 years ago. Today, hydrothermal processes are depositing clayey alteration products that have the potential to reset the stage for similar events in the future. Areas of active hydrothermal alteration occur in three representative settings: (1) An extensive area (greater than 12,000 m 2) of heated ground and slightly acidic boiling-point fumaroles at 76-82 °C at East and West Craters on the volcano's summit, where alteration products include smectite, halloysite and disordered kaolinite, cristobalite, tridymite, opal, alunite, gibbsite, and calcite. (2) A small area (less than 500 m 2) of heated ground and sub-boiling-point fumaroles at 55-60 °C on the upper flank at Disappointment Cleaver with smectite alteration and chalcedony, tridymite, and opal-A encrustations. Similar areas probably occur at Willis Wall, Sunset Amphitheater, and the South Tahoma and Kautz headwalls. (3) Sulfate- and carbon dioxide-enriched thermal springs at 9-24 °C on the lower flank of the volcano in valley walls beside the Winthrop and Paradise Glaciers, where calcite, opal-A, and gypsum are being deposited. In addition, chloride- and carbon dioxide-enriched thermal springs issue from thin sediments that overlie Tertiary rocks at, or somewhat beyond, the base of the volcanic edifice in valley bottoms of the Nisqually and Ohanapecosh Rivers. Maximum spring temperatures of 19-25 °C and 38-50 °C, respectively, and extensive travertine deposits have developed in these more distant localities. The heat flow, distribution of thermal activity, and nature of alteration minerals and fluids suggest a conceptual model of a narrow, central hydrothermal system within Mount Rainier, with steam-heated snowmelt at the summit craters and localized leakage of steam-heated fluids within 2 km of the summit. The lateral extent of the hydrothermal system is marked by discharge of

  12. Mo isotope fractionation during hydrothermal evolution of porphyry Cu systems

    Science.gov (United States)

    Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan

    2015-03-01

    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 hydrothermal evolution of porphyry systems. 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 hydrothermal systems 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 hydrothermal 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.

  13. Compartmentalized Fluid Flow In The Nevado Del Ruiz Volcano Hydrothermal System(S)

    Science.gov (United States)

    Zuluaga, C. A.; Mejia, E.

    2011-12-01

    Combination of several extensive and compressive fault/fracture systems with different lithologic units compartmentalized the hydrothermal system(s) in the vicinity of the Nevado del Ruiz volcano. Three main fault/fracture systems are observed in the Ruiz volcano area, a N10°-20°E system (San Jerónimo and Palestina faults), a N40°-60°W system (Villamaría-Termales, San Ramón, Nereidas, Río Claro, San Eugenio and Campoalegrito faults), and a N60°-80°E system (Santa Rosa fault). The NW trend system act as the main path for fluid circulation, location of faults and fractures belonging to this system and their intersections with other fault systems and/or with lithologic contacts control hot springs location. The observed fault location and hot spring location pattern allow to subdivide the hydrothermal system(s) 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 hydrothermal system or if there is more than one hydrothermal system.

  14. Development of micro-flow hydrothermal monitoring systems and their applications to the origin of life study on Earth.

    Science.gov (United States)

    Kawamura, Kunio

    2011-01-01

    Continuous extensive studies on thermophilic organisms have suggested that life emerged on hydrothermal systems on primitive Earth. Thus, it is well known that hydrothermal reactions are, therefore, very important to study fields deeply related to the origin-of-life study. Furthermore, the importance of hydrothermal and solvothermal systems 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 systems for hydrothermal reactions. The systems 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 hydrothermal origin-of-life have been successfully carried out.

  15. The importance of shallow hydrothermal island arc systems in ocean biogeochemistry

    NARCIS (Netherlands)

    Hawkes, J.A.; Connelly, D.P.; Rijkenberg, M.J.A.; Achterberg, E.P.

    2014-01-01

    Hydrothermal venting often occurs at submarine volcanic calderas on island arc chains, typically at shallower depths than mid-ocean ridges. The effect of these systems on ocean biogeochemistry has been under-investigated to date. Here we show that hydrothermal effluent from an island arc caldera was

  16. Thermodynamics of uranium/organic matter interactions in hydrothermal systems

    Science.gov (United States)

    Richard, L.

    2003-04-01

    Organic matter is commonly encountered in and around uranium and other ore deposits, which raises the question of the role played by organic compounds in the formation of these deposits (Landais and Gize, 1997). One of the best known examples is the observation of uraninite crystals entrapped within solid bitumens in the Oklo natural reactors. This observation led Nagy et al. (1991) to propose that a liquid, aliphatic-rich bitumen may have acted as a reductant to precipitate uraninite from hydrothermal solutions according to the reaction VIUO2+2(aq)+H_2O(l)=IVUO2(c)+2H^+(aq)+0.5 O2(g). The liquid bitumen was simultaneously oxidized into a polyaromatic solid, which may be represented by the reaction 2.7n- C20H42(l) + 17.85 O2(g) = C54H42(c)+35.7 H_2O(l) where n-C20H42(l) denotes n-eicosane present in the liquid bitumen, and C54H42(c) represents an idealized polyaromatic solid. Recent advances in theoretical organic geochemistry made it possible to generate a comprehensive thermodynamic database for hundreds of crystalline, liquid, gas and aqueous organic compounds of geochemical interest (Shock and Helgeson, 1990; Shock, 1995; Amend and Helgeson, 1997; Helgeson et al., 1998; Richard and Helgeson, 1998; Richard, 2001), which can be used together with thermodynamic properties for uranium-bearing minerals and aqueous species (Grenthe et al., 1992; Shock et al., 1997) to characterize uranium/organic matter interactions in hydrothermal systems as a function of temperature, pressure, oxygen fugacity, and organic matter composition. Activity-fO_2 diagrams have been constructed at a series of temperatures and pressures to investigate possible genetic relationships between uranium mineralizations and solid bitumens of various compositions.

  17. Coupled cycling of Fe and organic carbon in submarine hydrothermal systems: Impacts on Ocean Biogeochemistry?

    Science.gov (United States)

    German, Christopher; Sander, Sylvia; Legendre, Louis; Niquil, Nathalie; Working Group 135

    2014-05-01

    Submarine hydrothermal venting was first discovered in the late 1970s. For decades the potential impact that vent-fluxes could have on global ocean budgets was restricted to consideration of processes in hydrothermal plumes in which the majority of chemical species are incorporated into polymetallic sulfide and/or oxyhydroxide particles close to the ridge-crest and sink to the underlying seafloor. This restricted view of the role that hydrothermal systems might play in global-ocean budgets has been challenged, more recently, by the recognition that there might also be a significant flux of dissolved Fe from hydrothermal systems to the oceans that is facilitated through thermodynamically stable nanoparticles and organic complexation. The latest results from the recently completed US GEOTRACES program, which has traced high concentrations of dissolved Fe over long distances off-axis from the Southern East Pacific Rise near 15°S, only help to confirm the potential that such fluxes might be important at the global scale. In this paper we review field-based and modeling results, including investigations that we have carried out under the auspices of SCOR-InterRidge Working Group 135, that reveal potential relationships between organic carbon (Corg) and Fe in hydrothermal plumes and allow us to investigate the roles that hydrothermal systems may play in the global biogeochemical cycles of both Fe and Corg. Using the particularly well-studied EPR 9N hydrothermal system as our "type locality" - even though we recognize that no one site can adequately represent the diversity of all hydrothermal systems worldwide - our modeling efforts allow us to reach some significant conclusions concerning: the predicted partitioning of heat fluxes between focused and diffuse flow at ridge axes; and the recognition that while Corg fluxes associated with hydrothermal plume removal may be small on the global scale, they are likely to result in extremely pronounced fluxes, locally, to the

  18. Temporal and Seasonal Variations of the Hot Spring Basin Hydrothermal System, Yellowstone National Park, USA

    Directory of Open Access Journals (Sweden)

    Cheryl Jaworowski

    2013-12-01

    Full Text Available Monitoring Yellowstone National Park’s hydrothermal systems and establishing hydrothermal baselines are the main goals of an ongoing collaborative effort between Yellowstone National Park’s Geology program and Utah State University’s Remote Sensing Services Laboratory. During the first years of this research effort, improvements were made in image acquisition, processing and calibration. In 2007, a broad-band, forward looking infrared (FLIR camera (8–12 microns provided reliable airborne images for a hydrothermal baseline of the Hot Spring Basin hydrothermal system. From 2008 to 2011, night-time, airborne thermal infrared image acquisitions during September yielded temperature maps that established the temporal variability of the hydrothermal system. A March 2012 airborne image acquisition provided an initial assessment of seasonal variability. The consistent, high-spatial resolution imagery (~1 m demonstrates that the technique is robust and repeatable for generating corrected (atmosphere and emissivity and calibrated temperature maps of the Hot Spring Basin hydrothermal system. Atmospheric conditions before and at flight-time determine the usefulness of the thermal infrared imagery for geohydrologic applications, such as hydrothermal monitoring. Although these ground-surface temperature maps are easily understood, quantification of radiative heat from the Hot Spring Basin hydrothermal system is an estimate of the system’s total energy output. Area is a key parameter for calculating the hydrothermal system’s heat output. Preliminary heat calculations suggest a radiative heat output of ~56 MW to 62 MW for the central Hot Spring Basin hydrothermal system. Challenges still remain in removing the latent solar component within the calibrated, atmospherically adjusted, and emissivity corrected night-time imagery.

  19. Application of Hydrothermal and Non-Hydrothermal TiO2 Nanoporous Materials as New Adsorbents for Removal of Heavy Metal Ions from Aqueous System

    Directory of Open Access Journals (Sweden)

    Mansoor Anbia

    2016-06-01

    Full Text Available Hydrothermal and non-hydrothermal spherical TiO2 nanoporous with crystalline framework were prepared by sol-gel method. The Crystalline structures, morphologies and surface texturing of materials were determined by X-ray diffraction (XRD, scanning electron microscopy (SEM and N2 adsorption-desorption isotherms. The Hydrothermal spherical TiO2 nanoporous was found to have a narrow and strong pore size distribution peaks with average of 37.8 Å and pore volume of 0.41 cm3/g and the (Brunauer–Emmett–TellerBET specific surface area of 365 m2/g. Hydrothermal and non-hydrothermal spherical TiO2 nanoporous have been used as adsorbent to study of the adsorption behavior of Pb(II, Co(II and Ni(II ions from aqueous system in a batch system. Effect of equilibrium time on adsorption Pb(II, Co(II and Ni(II ions on these adsorbent was studied The results show that the shaking time 0.5 to 10h has no serious effect on the percentage of ions removal, and the adsorption is fast in all cases. The maximum uptake capacities of Hydrothermal and non-hydrothermal spherical TiO2 nanoporous was calculated. Both hydrothermal and non-hydrothermal TiO2 nanoporous materials were found to have very good potential as new adsorbents in removal of these ions. In batch systems the maximum uptake capacities of Pb(II, Ni(II and Co(II on the hydrothermal and non-hydrothermal TiO2 nanoporous materials was Co(II > Pb(II > Ni(II and Co(II > Ni(II > Pb(II, respectively.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Inversion approach for thermal data from a convecting hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Kasameyer, P.; Younker, L.; Hanson, J.

    1983-08-01

    Efforts to invert thermal data from 13 deep geothermal wells, and from additional shallow heat-flow holes, in order to determine the age and total flow rate of the Salton Sea hydrothermal system are described. The data were inverted for a very restrictive model: single-phase, horizontal flow along prescribed flowlines in a single aquifer bounded by an impermeable cap and base. With simplifying assumptions, the results are shown to depend on only two parameters, the system age, and the aquifer/cap thickness ratio. The surface gradient and temperature distribution within the cap are calculated analytically for all possible parameter values. Those parameters producing temperatures that agree with observations are identified, and the range of acceptable parameters is reduced by conclusions drawn from other geophysical data. The cap thickness is inferred to be 500m from thermal and lithologic data from the wells. The aquifer thickness is limited to less than 2500m by seismic, resistivity and magnetic data. It is concluded that if this model is valid, the system age is constrained between 3000 and 20,000 years.

  2. Magmatic MORB Volatiles, Seafloor Hydrothermal Systems and Abiotic Organic Synthesis

    Science.gov (United States)

    Holloway, J. R.

    2007-12-01

    A plausible model for the origin of the observed C-O-H volatiles observed in MORB glasses is that they were incorporated in primary melts of the upwelling mantle. Based on the observed ferric/ferrous ratios in MORB glass, it is probable that the MORB source mantle contained diamond or graphite, depending on pressure. If true, then during partial mantle melting the graphite/diamond would react with FeO1.5 in garnet/spinel and clinopyroxene to form CO2 which would dissolve in the melt as carbonate ion. Using equation of state models for CO2 activity and ferric/ferrous ratios in the magma it is possible to model the amount of carbonate dissolved in the basaltic magma as a function of the degree of melting (Holloway and O'Day, 2000). The results require that rising MORB magma will become saturated in CO2 at depths much greater than those proposed for MORB magma chambers. Conversely H2O values observed in MORB glasses are far below saturation. However as CO2 reaches saturation and exsolves from the melt the low fO2 imposed by the low ferric/ferrous ratio results in a high H2/H2O ratio in the exsolving supercritical fluid. We have shown that fluids with this composition produce methanol (CH3OH) in the presence of magnetite at seafloor hydrothermal P-T conditions in a flow-through system (Voglesonger, et al., 2001) and that aqueous methanol solutions react in montmorillonite clay interlayers to form a wide variety of complex hydrocarbon molecules, the most abundant being hexamethyl benzene (Williams, et al., 2005). Methyl stearate (C17H35COOCH3) was also observed in moderate amounts. Holloway, J. R. and P. A. O'Day (2000). "Production of CO2 and H2 by Diking-Eruptive Events at Mid-Ocean Ridges: Implications for Abiotic Organic Synthesis and Global Geochemical Cycling." International Geology Review 42: 673-683. Voglesonger, K. M., J. R. Holloway, E. E. Dunn, P. J. Dalla-Betta and P. A. O'Day (2001). "Experimental Abiotic Synthesis of Methanol in Seafloor Hydrothermal

  3. Application of Hyperspectral Methods in Hydrothermal Mineral System Studies

    Science.gov (United States)

    Laukamp, Carsten; Cudahy, Thomas; Gessner, Klaus; Haest, Maarten; Cacetta, Mike; Rodger, Andrew; Jones, Mal; Thomas, Matilda

    2010-05-01

    hyperspectral mineral mapping of contaminating, carbonate- or clay-rich zones helped to better constrain the ore zones and the genesis of the mineral system. 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 hydrothermal 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 systems. The advantages of hyperspectral techniques over conventional exploration methods include: (1) the fast and

  4. New insights into the Kawah Ijen hydrothermal system from geophysical data

    Science.gov (United States)

    Caudron, Corentin; Mauri, G.; Williams-Jones, Glyn; Lecocq, Thomas; Syahbana, Devy Kamil; de Plaen, Raphael; Peiffer, Loic; Bernard, Alain; Saracco, Ginette

    2017-01-01

    Volcanoes with crater lakes and/or extensive hydrothermal systems pose significant challenges with respect to monitoring and forecasting eruptions, but they also provide new opportunities to enhance our understanding of magmatic–hydrothermal processes. Their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of magmatic unrest and eruption, yet they also enable sampling and monitoring of geochemical tracers. Here, we describe the outcomes of a highly focused international experimental campaign and workshop carried out at Kawah Ijen volcano, Indonesia, in September 2014, designed to answer fundamental questions about how to improve monitoring and eruption forecasting at wet volcanoes.

  5. Mass transfer constraints on the chemical evolution of an active hydrothermal system, Valles caldera, New Mexico

    Science.gov (United States)

    White, A.F.; Chuma, N.J.; Goff, F.

    1992-01-01

    Partial equilibrium conditions occur between fluids and secondary minerals in the Valles hydrothermal system, 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 hydrothermal system and denotes a geochemically and isotopically open system. 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 hydrothermal systems in rhyolitic rocks. ?? 1992.

  6. Hydrothermal alteration of Hercynian granites, its significance to the evolution of geothermal systems in granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Jose M.; Matias, Maria J.; Basto, Maria J.; Aires-Barros, Luis A. [Instituto Superior Tecnico, Centro de Petrologia e Geoquimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Carreira, Paula M. [Instituto Tecnologico e Nuclear, Estrada Nacional n 10, 2686 - 953 Sacavem (Portugal); Goff, Fraser E. [Earth and Planetary Sciences Department, Univ. of New Mexico, Albuquerque, NM 87131 (United States)

    2010-06-15

    We discuss geochemical and isotopic ({sup 18}O/{sup 16}O, {sup 2}H/{sup 1}H and {sup 87}Sr/{sup 86}Sr) data recording the hydrothermal alteration of northern Portuguese Hercynian granites by Na-HCO{sub 3}-CO{sub 2}-rich mineral waters. Whole-rock samples from drill cores of Vilarelho da Raia granite have {delta}{sup 18}O values in the +11.47 to +10.10 permille range. The lower values correspond to highly fractured granite samples displaying vein and pervasive alteration. In the pervasive alteration stage, which probably results from a convective hydrothermal system set up by the intrusion of the granites, the metamorphic waters are in equilibrium with hydrous minerals. In contrast, the vein alteration of these granitic rocks was caused by water of meteoric origin. The oxygen ratios between water (W) and rock (R), the so-called W/R ratios, obtained for the open system (where the heated water is lost from the system by escape to the surface) range between 0.05 and 0.11, suggesting that the recrystallization of the veins was influenced by a small flux of meteoric water. Stable isotope analyses performed on the cores show that the vein alteration stage relates to post-emplacement tectonic stresses acting on the granite, probably of late Hercynian age. Our results are consistent with the existence of two separate alteration events (pervasive and vein) caused by hydrothermal waters of different isotopic characteristics. The studies presented in this paper should be viewed as a natural analogue that uses the alteration features observed in a fossil geothermal system at Vilarelho da Raia to assess possible water-rock reactions presently occurring at depth in granitic rocks of the nearby Chaves area. (author)

  7. Terrestrial Iron Hot Springs as Analogs for Ancient Martian Hydrothermal Systems

    Science.gov (United States)

    Parenteau, M. N.; Farmer, J. D.; Jahnke, L. L.; Cady, S. L.

    2010-04-01

    We have been studying a subaerial terrestrial iron hot spring as an potential analog for hydrothermal systems on Mars. In this multidisciplinary study, we have characterized the aqueous geochemistry, mineralogy, and microbial biosignatures at Chocolate Pots hot springs.

  8. Magnetic properties related to hydrothermal alteration processes at the Escondida porphyry copper deposit, northern Chile

    Science.gov (United States)

    Riveros, K.; Veloso, E.; Campos, E.; Menzies, A.; Véliz, W.

    2014-08-01

    Fluid-rock interaction related to the circulation of hydrothermal fluids can strongly modify the physicochemical properties of wall rocks in porphyry Cu deposits. These processes can also produce compositional and textural changes in ferromagnetic minerals, which can be quantified using magnetic methods. In the Escondida porphyry Cu deposit of northern Chile, each hydrothermally altered lithology is characterized by a discrete assemblage of Fe-Ti oxide minerals. These minerals have distinctive bulk magnetic susceptibility ( K bulk), temperature-dependent magnetic susceptibility, and magnetic hysteresis parameters. Selectively altered rocks (i.e., potassic and chloritic alteration types) exhibit the highest K bulk values (>3.93 × 10-3 SI units), and their hysteresis parameters indicate multidomain magnetic mineral behavior. This suggests that these rocks are composed of the coarsest magnetic grain sizes within the deposit. Optical analyses and susceptibility-temperature curves confirm that the magnetic signals in selectively altered rocks are mainly carried by secondary magnetite. In contrast, pervasively altered rocks (i.e., quartz-sericite and argillic alteration types) exhibit low K bulk values (hydrothermal alteration processes, Fe-Ti oxide minerals, and magnetic properties of the wall rock in the Escondida deposit. These magnetic methods can be considered a sensitive and efficient petrophysical tool for the identification and semi-quantification of alteration assemblages, and facilitating the recognition and mapping of discrete hydrothermal zones during exploration and operation of porphyry Cu deposits.

  9. Source Dynamics of Long-Period Seismicity in Volcanic and Hydrothermal Systems

    Science.gov (United States)

    Chouet, B. A.

    2006-12-01

    Long-period (LP) seismicity, including individual LP events and tremor, is widely observed in relation to magmatic and hydrothermal 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 system 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 hydrothermal 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 system 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 systems, while misty gases, steam and bubbly water commonly represent LP events of hydrothermal origin. Observations carried out in different volcanic settings point to a wide variety of LP excitation mechanisms. At Stromboli

  10. Zn isotopes as a traccer of bedrock weathering in hydrothermal system of la Soufrière volcano, Guadeloupe (FWI)

    Science.gov (United States)

    Chen, J.; Gaillardet, J.; Dessert, C.; Louvat, P.; Villemant, B.; Birck, J.; Crispi, O.

    2012-12-01

    The active hydro-volcanic systems are characterized by intense hydrothermal activities associated with acidic fumaroles and hot springs and play an important role in global silicate weathering. As the ultimate weathering loads are mostly transported into ocean through water, studies of hydrothermal waters can give interesting clues about the complex interactions among magmatic fluids, bed-rock, and aquifers fed by meteoritic water or seawater. Zn is a volatile element during magma degassing. However, the behavior of Zn in hydrothermal water systems is still unclear. Recent studies have demonstrated the interest of Zn isotopes for investigating water-rock interactions. Speciation-related fractionation as well as source-related fractionation between its isotopes (about 3‰ in δ66Zn unit) make Zn isotopes a promising tracer for studying the mobility of metals during weathering, hydrothermalism, magma degassing and ore formation. Although previous studies have focused on the processes fractionating Zn isotopes in hydrothermal solid deposits, seafloor vents and fumarolic gas, Zn isotope composition of hydrothermal waters in continental arc setting has not been investigated so far. We developed a new one-step purification method for the separation of Zn from Fe- and SO4-enriched hydrothermal solutions using anion-exchange column. The protocol was validated by multiple tests on varying eluants and Zn concentrations, and by investigating the recovery and the reproducibility of measured isotopic ratios. Using this method, water samples from 8 hydrothermal springs and 6 gas samples from two fumaroles of la Soufrière active volcano on the Guadeloupe island (French West Indies, FWI) were analyzed for Zn isotope composition. Compared to the small δ66Zn range for the fumarolic gases (from 0.21‰ to 0.35‰) and local bedrocks (from -0.14‰ to 0.42‰), all water samples displayed a relative large δ66Zn variation of 1.44‰ (from -0.43‰ to 1.01‰). This is about 70% of

  11. Miocene fossil hydrothermal system associated with a volcanic complex in the Andes of central Chile

    Science.gov (United States)

    Fuentes, Francisco; Aguirre, Luis; Vergara, Mario; Valdebenito, Leticia; Fonseca, Eugenia

    2004-11-01

    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 hydrothermal 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 hydrothermal system developed inside a volcanic complex during the Miocene. The hydrothermal system has been eroded to a

  12. Chaotic thermohaline convection in low-porosity hydrothermal systems

    NARCIS (Netherlands)

    Schoofs, Stan; Spera, Frank J.; Hansen, Ulrich

    2001-01-01

    Fluids circulate through the Earth's crust perhaps down to depths as great as 5^15 km, based on oxygen isotope systematics of exhumed metamorphic terrains, geothermal fields, mesozonal batholithic rocks and analysis of obducted ophiolites. Hydrothermal flows are driven by both thermal and chemical b

  13. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Directory of Open Access Journals (Sweden)

    Yao Zhang

    Full Text Available To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems 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 hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal 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 hydrothermal system. We speculated that mixing between hydrothermal 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 hydrothermal systems off the coast of NE Taiwan.

  14. The eastern Tibetan Plateau geothermal belt, western China: Geology, geophysics, genesis, and hydrothermal system

    Science.gov (United States)

    Tang, Xianchun; Zhang, Jian; Pang, Zhonghe; Hu, Shengbiao; Tian, Jiao; Bao, Shujing

    2017-10-01

    The eastern Tibetan Plateau geothermal belt (ETGB), which is located in 98-102°E, 28-32°N, belongs to the eastern part of the Mediterranean-Himalayan geothermal belt. Recently, about 248 natural hot springs have been found in the ETGB. > 60% of these springs have temperatures of > 40 °C, and 11 springs have temperature above the local water boiling point. Using the helium isotopic data, gravity, magnetic and seismic data, we analyzed the thermal structure and the relationship between hydrothermal activity and geothermal dynamics of the ETGB. Results show that: (1) the 248 springs can be divided into three geothermal fields: Kangding-Luhuo geothermal field (KGF), Litang-Ganzi geothermal field (LGF) and Batang-Xiangcheng geothermal field (BGF). The BGF and LGF have hot crust and warm mantle, and are characterized by the higher heat flux (66.26 mW/m2), and higher ratios of crust-derived heat flux to total flux (47.46-60.62%). The KGF has cool crust and hot mantle, and is characterized by the higher heat flux and lower Qc/Qm; (2) there is a relatively 4-6 m higher gravimetric geoid anomaly dome which is corresponding with the ETGB. And in hydrothermal activity areas of the BGF and LGF, there is a northwest - southeast-trending tensile stress area and the upper-middle crust uplift area; (3) an abnormal layer exists in the middle-lower crust at a depth of 13-30 km beneath the ETGB, and this layer is 8-10 km thick and is characterized by lower velocity (Vp 2.5), high conductivity ( 10 Ω·m) and high temperature (850-1000 °C). Finally, based on the heat source and geological and geophysical background, we propose Kangding-type and Batang-type hydrothermal system models in the ETGB.

  15. Resistivity structure of the Furnas hydrothermal system (Azores archipelago, Portugal) from AMT and ERT imaging.

    Science.gov (United States)

    Byrdina, Svetlana; Vandemeulebrouck, Jean; Rath, Volker; Silva, Catarina; Hogg, Colin; Kiyan, Duygu; Viveiros, Fatima; Eleuterio, Joana; Gresse, Marceau

    2016-04-01

    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 hydrothermal 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 hydrothermal system 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 hydrothermal system (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 hydrothermal 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

  16. Geologic and hydrologic controls on the economic potential of hydrothermal systems associated with upper crustal plutons

    Science.gov (United States)

    Weis, Philipp; Driesner, Thomas; Scott, Samuel; Lecumberri-Sanchez, Pilar

    2016-04-01

    Heat and mass transport in hydrothermal systems associated with upper crustal magmatic intrusions can result in resources with large economic potential (Kesler, 1994). Active hydrothermal systems can form high-enthalpy geothermal reservoirs with the possibility for renewable energy production. Fossil continental or submarine hydrothermal systems 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 hydrothermal 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 systems, as well as knowledge of fluid and rock properties and their interactions in natural systems. 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-hydrothermal 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-hydrothermal systems 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

  17. Evidence for a spatially extensive hydrothermal system at the Ries impact structure, Germany

    Science.gov (United States)

    Sapers, H. M.; Osinski, G. R.; Flemming, R. L.; Buitenhuis, E.; Banerjee, N. R.; Tornabene, L. L.; Blain, S.; Hainge, J.

    2017-02-01

    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 hydrothermal alteration was recognized. Previous studies suggested that pervasive, high-temperature hydrothermal activity was restricted to the area within the "inner ring" (i.e., the crater-fill impactite units). Here we present mineralogical evidence for localized hydrothermal 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 hydrothermal activity characterized by an illitic component and minor smectite; (3) hydrothermal activity at depth characterized by smectite, a minor illitic component, and calcite; (4) hydrothermal activity at depth characterized by smectite, a minor illitic component, calcite, zeolites, and clinochlore; and (5) pervasive hydrothermal activity at depth characterized by smectite, a minor illitic component, and minor clinochlore. These data spatially extend the Ries postimpact hydrothermal system suggesting a much more extensive, complex, and dynamic system 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.

  18. Sub-glacial Origin of the Hot Springs Bay Valley hydrothermal System, Akutan, Alaska

    Science.gov (United States)

    Stelling, P. L.; Tobin, B.; Knapp, P.

    2015-12-01

    Exploration for geothermal energy in Hot Springs Bay Valley (HSBV) on Akutan Island, Alaska, has revealed a rich hydrothermal 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 hydrothermal 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 hydrothermal 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 hydrothermal system formation and geothermal resource potential. References: Bekele, E., Rostron, B. and Person, M. (2003) Fluid pressure

  19. The magnetic signature of ultramafic-hosted hydrothermal systems (Invited)

    Science.gov (United States)

    Szitkar, F.; Dyment, J.; Honsho, C.; Horen, H.; Fouquet, Y.

    2013-12-01

    While the magnetic response of basalt-hosted hydrothermal sites is well known, that of ultramafic-hosted hydrothermal sites (UMHS) remains poorly documented. Here we present the magnetic signature of three of the six UMHS investigated to date on the Mid-Atlantic Ridge, i.e. sites Rainbow, Ashadze (1 and 2), and Logachev. Two magnetic signatures are observed. Sites Rainbow and Ashadze 1 are both characterized by a positive reduced-to-the-pole magnetic anomaly, i.e. a positive magnetization contrast. Conversely, sites Ashadze 2 and Logachev do not exhibit any clear magnetic signature. Rock-magnetic measurements on samples from site Rainbow reveal a strong magnetization (~30 A/m adding induced and remanent contributions) borne by sulfide-impregnated serpentinites; the magnetic carrier being magnetite. This observation can be explained by three (non exclusive) processes: (1) higher temperature serpentinization at the site resulting in the formation of more abundant / more strongly magnetized magnetite; (2) the reducing hydrothermal fluid protecting magnetite at the site from the oxidation which otherwise affects magnetite in contact with seawater; and (3) the formation of primary (hydrothermal) magnetite. We apply a new inversion method developed by Honsho et al. (2012) to the high-resolution magnetic anomalies acquired 10 m above seafloor at sites Rainbow and Ashadze 1. This method uses the Akaike Bayesian Information Criterion (ABIC) and takes full advantage of the near-seafloor measurements, avoiding the upward-continuation (i.e. loss of resolution) of other inversion schemes. This inversion reveals a difference in the intensity of equivalent magnetization obtained assuming a 100 m thick magnetic layer, ~30 A/m at site Rainbow and only 8A/m at site Ashadze, suggesting a thinner or less magnetized source for the latter. Hydrothermal sites at Ashadze 2 and Logachev are much smaller (of the order of 10 m) than the previous ones (several 100 m). These sites, known as

  20. Investigation of Icelandic rift zones reveals systematic changes in hydrothermal outflow in concert with seismic and magmatic events: Implications for investigation of Mid-Ocean Ridge hydrothermal systems

    Science.gov (United States)

    Curewitz, D.; Karson, J. A.

    2010-12-01

    Co-registration of several generations of geological data was carried out for hydrothermal 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 hydrothermal sites will inform investigation of similar data from mid-ocean ridge hydrothermal systems 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 systems. 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 hydrothermal 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 hydrothermal outflow behavior. Recent seismic events are strongly linked to well-mapped changes in fracture/fault population and hydrothermal flow behavior in the Hveragerdi region, near Hengill, and provide higher

  1. Volcano-Hydrothermal Systems of the Central and Northern Kuril Island Arc - a Review

    Science.gov (United States)

    Kalacheva, E.; Taran, Y.; Voloshina, E.; Ptashinsky, L.

    2015-12-01

    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 hydrothermal activity, complementary to the fumarolic activity in their craters. There are several types of volcano-hydrothermal systems on the islands. At Paramushir, Shiashkotan and Ketoy the thermal manifestations are acidic to ultra-acidic water discharges associated with hydrothermal 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 hydrothermal 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-hydrothermal system 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 hydrothermal 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-hydrothermal

  2. An unit commitment model for hydrothermal systems; Um modelo de unit commitment para sistemas hidrotermicos

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Thiago de Paula; Luciano, Edson Jose Rezende; Nepomuceno, Leonardo [Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil). Dept. de Engenharia Eletrica], Emails: ra611191@feb.unesp.br, edson.joserl@uol.com.br, leo@feb.unesp.br

    2009-07-01

    A model of Unit Commitment to hydrothermal systems that includes the costs of start/stop of generators is proposed. These costs has been neglected in a good part of the programming models for operation of hydrothermal systems (pre-dispatch). The impact of the representation of costs in total production costs is evaluated. The proposed model is solved by a hybrid methodology, which involves the use of genetic algorithms (to solve the entire part of the problem) and sequential quadratic programming methods. This methodology is applied to the solution of an IEEE test system. The results emphasize the importance of representation of the start/stop in the generation schedule.

  3. Conceptual geologic model and native state model of the Roosevelt Hot Springs hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Faulder, D.D.

    1991-01-01

    A conceptual geologic model of the Roosevelt Hot Springs hydrothermal system was developed by a review of the available literature. The hydrothermal system 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 hydrothermal system can be used to establish boundary conditions for further study of the geothermal reservoir. 33 refs., 9 figs.

  4. Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano

    Science.gov (United States)

    Thal, Janis; Tivey, Maurice; Yoerger, Dana R.; Bach, Wolfgang

    2016-09-01

    North Su is a double-peaked active andesite submarine volcano located in the eastern Manus Basin of the Bismarck Sea that reaches a depth of 1154 m. It hosts a vigorous and varied hydrothermal system with black and white smoker vents along with several areas of diffuse venting and deposits of native sulfur. Geologic mapping based on ROV observations from 2006 and 2011 combined with morphologic features identified from repeated bathymetric surveys in 2002 and 2011 documents the emplacement of a volcanic cryptodome between 2006 and 2011. We use our observations and rock analyses to interpret an eruption scenario where highly viscous, crystal-rich andesitic magma erupted slowly into the water-saturated, gravel-dominated slope of North Su. An intense fragmentation process produced abundant blocky clasts of a heterogeneous magma (olivine crystals within a rhyolitic groundmass) that only rarely breached through the clastic cover onto the seafloor. Phreatic and phreatomagmatic explosions beneath the seafloor cause mixing of juvenile and pre-existing lithic clasts and produce a volcaniclastic deposit. This volcaniclastic deposit consists of blocky, non-altered clasts next, variably (1-100%) altered clasts, hydrothermal precipitates and crystal fragments. The usually applied parameters to identify juvenile subaqueous lava fragments, i.e. fluidal shape or chilled margin, were not applicable to distinguish between pre-existing non-altered clasts and juvenile clasts. This deposit is updomed during further injection of magma and mechanical disruption. Gas-propelled turbulent clast-recycling causes clasts to develop variably rounded shapes. An abundance of blocky clasts and the lack of clasts typical for the contact of liquid lava with water is interpreted to be the result of a cooled, high-viscosity, crystal-rich magma that failed as a brittle solid upon stress. The high viscosity allows the lava to form blocky and short lobes. The pervasive volcaniclastic cover on North Su is

  5. Assessment of hydrothermal processes associated with Proterozoic mineral systems in Finland using self-organizing maps.

    Science.gov (United States)

    Lerssi, J.; Sorjonen-Ward, P.; Fraser, S. J.; Ruotsalainen, A.

    2009-04-01

    An increasingly urgent challenge in mineral system analysis is to extract relevant information from diverse datasets, and to effectively discriminate between "hydrothermal noise" and alteration and structures that may relate to significant mineralization potential. The interpretation of geophysical data is notorious for the problem of ambiguity in defining source dimensions and geometry. An additional issue, which also applies to geochemical and hyperspectral datasets, in terrain that has been overprinted by several tectonic, metamorphic and hydrothermal events, is that while anomalies represent the sum of geological processes affecting an area, we are usually interesting in extracting the signals diagnostic of a mineralizing event. Spatial analysis using weights of evidence, fuzzy logic and neural networks have been widely applied to mineral prospectivity assessment in recent years. Here however, we present an alternative, albeit complementary approach, based on the concept of self-organizing maps [1], in which natural patterns in large, unstructured datasets are derived, correlated and readily visualized, provides an alternative approach to analysis of geophysical and geochemical anomalies and integration with other geological data. We have applied SiroSOM software to airborne and ground magnetic, EM and radiometric data for two mutually adjacent areas in eastern Finland that have superficially similar structural architecture and geophysical expression, yet differ significantly in terms of mineral system character: (1) the Outokumpu Cu-Co-Zn-Ni system, hosted by metamorphosed serpentinites and their hydrothermal derivatives, which are usually highly magnetic due to both magnetite and pyrrhotite; (2) the Hammaslahti Cu-Zn system, hosted by coarse-clastic turbidites intercalated with mafic volcanics and graphitic pelites having characteristically intense magnetic and EM responses. Although the initial stage of the analysis is unsupervised, ongoing iteration and

  6. Coupled cycling of Fe and organic carbon in submarine hydrothermal systems: Modelling approach

    Science.gov (United States)

    Legendre, Louis; German, Christopher R.; Sander, Sylvia G.; Niquil, Nathalie

    2014-05-01

    It has been recently proposed that hydrothermal plumes may be a significant source of dissolved Fe to the oceans. In order to assess this proposal, we investigated the fate of dissolved Fe released from hydrothermal systems to the overlying ocean using an approach that combined modelling and field values. We based our work on a consensus conceptual model developed by members of SCOR-InterRidge Working Group 135. The model was both complex enough to capture the main processes of dissolved Fe released from hydrothermal systems and chemical transformation in the hydrothermal plume, and simple enough to be parameterized with existing field data. It included the following flows: Fe, water and heat in the high temperature vent fluids, in the fluids diffusing around the vent, and in the entrained seawater in the buoyant plume; Fe precipitation in polymetallic sulphides near the vent; transport of Fe in the non-buoyant plume, and both its precipitation in particles onto the sea bottom away from the vent and dissolution into deep-sea waters. In other words, there were three Fe input flows into the buoyant hydrothermal plume (vent-fluids; entrained diffuse flow; entrained seawater) and three Fe output flows (sedimentation from the buoyant plume as polymetallic sulfides; sedimentation from the non-buoyant plume in particulate form; export to the deep ocean in dissolved or nanoparticulate form). The output flows balanced the input flows. We transformed the conceptual model into equations, and parameterized these with field data. To do so, we assumed that all hydrothermal systems, globally, can be represented by the circumstances that prevail at the EPR 9°50'N hydrothermal field, although we knew this assumption not to be accurate. We nevertheless achieved, by following this approach, two important goals, i.e. we could assemble into a coherent framework, for the first time, several discrete data sets acquired independently over decades of field work, and we could obtain model

  7. Chemical evolution of life-like system under hydrothermal environments: prebiotic formation, degradation, and functions regarding protein-like molecules and RNA

    Science.gov (United States)

    Kawamura, Kunio

    The accumulation of biopolymers without enzymes is an essential step for the chemical evolu-tion towards a primitive life-like system. Previously, we discussed the relationship between the RNA world hypothesis and the hydrothermal origin of life hypothesis on the basis of the em-pirical data of RNA behaviors under the hydrothermal environments examined using real-time monitoring technique for hydrothermal 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 hydrothermal environments. These observations have shown the possibility that oligopeptides could have been accumulated under near submarine hydrother-mal vent environments on primitive Earth within the relatively short time scale. However, the formation of oligopeptides under the simulated hydrothermal 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 hydrothermal flow reactor system (MHFR), which enables monitoring hydrothermal 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.

  8. SI-Hydro: an information system for the Brazilian hydrothermal system; SI-Hidro: um sistema de informacao para o sistema hidrotermico brasileiro

    Energy Technology Data Exchange (ETDEWEB)

    Fontanini, Walcir

    1995-03-01

    An information system for the Brazilian hydrothermal system denominated SI-Hydro is presented. This information system supplies data on the hydroelectric and thermoelectric park and can be used in the main elements recognition and in the planning and management of the whole system. The information system uses the product INGRES in the platform UNIX/X-Windows, which supplies resources so much for access to the database as for the interface man machine through the fourth generation language denominated Windows4GL. The next main topics are presented: information systems concepts and its relation with the direction levels to an organization and implications for the hydrothermal system operation planning in the scenarios of short, medium and long terms; thermal and hydroelectric plants operation routine details; the most used technical terms definition; and mathematical physical typical plants processes modeling presentation.

  9. A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

    DEFF Research Database (Denmark)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle

    2017-01-01

    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 multistage hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed...... in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783–1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal alteration halo of biotite-arsenopyrite-sericite-actinolite-pyrrhotite(-chloriteplagioclase- 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 hydrothermal calcite-titanite alteration assemblage is dated to ca. 1766 Ma; however, this alteration is highly isolated...

  10. Identifying bubble collapse in a hydrothermal system using hiddden Markov models

    Science.gov (United States)

    Dawson, Phillip B.; Benitez, M.C.; Lowenstern, Jacob B.; Chouet, Bernard A.

    2012-01-01

    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 hydrothermal 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 hydrothermal 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 hydrothermal system, with the rate of collapse being controlled by surficial temperatures and daytime evaporation rates.

  11. System and process for efficient separation of biocrudes and water in a hydrothermal liquefaction system

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Oyler, James R.; Rotness, Jr, Leslie J.; Schmidt, Andrew J.; Zacher, Alan H.

    2016-08-02

    A system and process are described for clean separation of biocrudes and water by-products from hydrothermal 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.

  12. Alkanes and alkenes in Mediterranean volcanic-hydrothermal systems: origins and geothermometry

    Science.gov (United States)

    Fiebig, Jens; D'Alessandro, Walter; Tassi, Franco; Woodland, Alan

    2010-05-01

    It is still a matter of debate if nature provides conditions for abiogenic production of hydrocarbons. Methane (C1) and the C2+ alkanes emanating from ultramafic hydrothermal systems such as Lost City have been considered to be abiogenic in origin, mainly because of the occurrence of an isotopic reversal between methane and the C2+hydrocarbons and C1/C2+ ratios >1000 [1]. Abiogenic production of methane has been postulated to occur under the relatively oxidizing redox conditions of continental-hydrothermal systems, too. It was observed that temperatures received from the H2-H2O-CO-CO2-CH4 geoindicator were coincident with temperatures derived from carbon isotope partitioning between CO2 and CH4in gases released from the Mediterranean volcanic-hydrothermal systems of Nisyros (Greece), Vesuvio and Ischia (both Italy) [2]. Such equilibrium pattern, if not fortuitous, can only be obtained if mantle- and marine limestone-derived CO2 is reduced to CH4. At Nisyros, observed C1/C2+ ratios from 300-4000 are in agreement with an abiogenic origin of the methane. Ethane and propane, however, were shown to be non-genetic with CO2 and methane. C1/C2 and C2/C3 distribution ratios may point to the admixture of small amounts of hydrocarbons deriving from the thermal decomposition of organic matter along with abiogenically equilibrated methane essentially devoid of the higher hydrocarbons [3]. Here, we provide new isotopic and hydrocarbon concentration data on several Mediterranean volcanic-hydrothermal systems, including Nisyros, Vesuvio, Ischia, Vulcano, Solfatara and Pantelleria. Wherever possible, we have extended our data set for the hydrogen isotope composition of CH4 and H2, n-alkane- and alkene/alkane-distribution ratios. At Nisyros, measured alkene/alkane- and H2/H2O concentration ratios confirm the attainment of equilibrium between CO2 and CH4. CO2 and CH4 appear to have equilibrated in the liquid phase at temperatures of ~360° C and redox conditions closely corresponding

  13. Strontium and oxygen isotopic profiles through 3 km of hydrothermally altered oceanic crust in the Reykjanes Geothermal System, Iceland

    Science.gov (United States)

    Marks, N. E.; Zierenberg, R. A.; Schiffman, P.

    2010-12-01

    The Iceland Deep Drilling Program well of opportunity RN-17 was drilled 3 km into a section of hydrothermally altered basaltic crust in the Reykjanes geothermal system in Iceland. The system is located on the landward extension of the Mid-Atlantic Ridge, and the circulating hydrothermal fluid is modified seawater, making Reykjanes a useful analogue for mid-oceanic ridge hydrothermal systems. 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 system, 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 hydrothermal 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 hydrothermal history.

  14. Early Archaean sedimentary basins: depositional environment and hydrothermal systems. Geologica Ultraiectina (244)

    NARCIS (Netherlands)

    de Vries, S.T.|info:eu-repo/dai/nl/33656791X

    2004-01-01

    The topic of this thesis is the Early Archaean environment and hydrothermal systems in the Barberton Greenstone Belt (BGB) in South Africa, and the Coppin Gap Greenstone Belt (CGGB) in the Pilbara, Australia. Focus within these greenstone belts is on the ~3.45-3.42 Ga Buck Ridge volcano-sedimentary

  15. Poroelastic response of mid-ocean ridge hydrothermal systems to ocean tidal loading: Implications for shallow permeability structure

    Science.gov (United States)

    Barreyre, Thibaut; Sohn, Robert A.

    2016-02-01

    We use the time delay between tidal loading and exit-fluid temperature response for hydrothermal 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. Hydrothermal 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 Endeavour field exhibit both high and low phase lags, suggestive of a transitional behavior. Our results demonstrate that tidal forcing perturbs hydrothermal flow across the global MOR system, 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.

  16. Hydrothermal alteration in the Reykjanes geothermal system: Insights from Iceland deep drilling program well RN-17

    Science.gov (United States)

    Marks, Naomi; Schiffman, Peter; Zierenberg, Robert A.; Franzson, Hjalti; Fridleifsson, Gudmundur Ó.

    2010-01-01

    The Reykjanes geothermal system is a seawater-recharged hydrothermal system that appears to be analogous to seafloor hydrothermal systems in terms of host rock type and low water/rock alteration. The similarities make the Reykjanes system a useful proxy for seafloor vents. At some time during the Pleistocene, the system 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 system. The basaltic host rock includes hyaloclastite, breccia, tuff, extrusive basalt, diabase, as well as a marine sedimentary sequence. The progressive hydrothermal 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 systems 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 hydrothermal

  17. A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

    Science.gov (United States)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle; Bagas, Leon; Thomsen, Tonny B.

    2017-03-01

    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 hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783-1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal 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 hydrothermal 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 hydrothermal 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 hydrothermal epidote-calcite-zoisite alteration assemblage with numerous accessory minerals forms halos surrounding the late-stage fractures. The contrasting hydrothermal 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.

  18. A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

    Science.gov (United States)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle; Bagas, Leon; Thomsen, Tonny B.

    2016-07-01

    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 hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783-1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal 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 hydrothermal 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 hydrothermal 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 hydrothermal epidote-calcite-zoisite alteration assemblage with numerous accessory minerals forms halos surrounding the late-stage fractures. The contrasting hydrothermal 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.

  19. Interconnected hydro-thermal systems - Models, methods, and applications

    DEFF Research Database (Denmark)

    Hindsberger, Magnus

    2003-01-01

    , it has been analysed how the Balmorel model can be used to create inputs related to transmissions and/or prices to a more detailed production scheduling model covering a subsystem of the one represented in the Balmorel model. As an example of application of the Balmorel model, the dissertation presents...... results of an environmental policy analysis concerning the possible reduction of CO2, the promotion of renewable energy, and the costs associated with these aspects. Another topic is stochastic programming. A multistage stochastic model has been formulated of the Nordic power system. This allows analyses...

  20. System Study on Hydrothermal Gasification Combined with a Hybrid Solid Oxide Fuel Cell Gas Turbine

    OpenAIRE

    Toonssen, Richard; Aravind, P.V.; Smit, Gerton; Woudstra, Nico; Verkooijen, Adrian

    2010-01-01

    Abstract The application of wet biomass in energy conversion systems is challenging, since in most conventional systems the biomass has to be dried. Drying can be very energy intensive especially when the biomass has a moisture content above 50 wt% on a wet basis. The combination of hydrothermal biomass gasification and a solid oxide fuel cell (SOFC) gas turbine (GT) hybrid system could be an efficient way to convert very wet biomass into electricity. Therefore, thermodynamic evalu...

  1. Permeability Reduction in Passively Degassing Seawater-dominated Volcanic-hydrothermal systems: Processes and Perils on Raoul Island, Kermadecs (NZ)

    Science.gov (United States)

    Christenson, B. W.; Reyes, A. G.

    2014-12-01

    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 hydrothermal system on the island. The eruption released some 200 T of SO2, implicating the involvement of a deep magmatic vapor input into the system 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 hydrothermal system, but mainly through areas that did not correspond to the 2006 eruption vents. The lack of a pre-eruptive hydrothermal system response related to the seismic event in 2006 can be explained by the presence of a hydrothermal 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 hydrothermal system 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

  2. Energy landscapes shape microbial communities in hydrothermal systems on the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Dahle, Håkon; Økland, Ingeborg; Thorseth, Ingunn H; Pederesen, Rolf B; Steen, Ida H

    2015-07-01

    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 hydrothermal systems through an investigation of two geochemically different basalt-hosted hydrothermal systems 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 hydrothermal 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 hydrothermal 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.

  3. Fluid geochemistry of the Mondragone hydrothermal systems (southern Italy): water and gas compositions vs. geostructural setting

    Science.gov (United States)

    Cuoco, Emilio; Minissale, Angelo; Di Leo, Antonella "Magda"; Tamburrino, Stella; Iorio, Marina; Tedesco, Dario

    2017-02-01

    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 hydrothermal 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 systems 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 hydrothermal systems. 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

  4. Aldehydes in hydrothermal solution - Standard partial molal thermodynamic properties and relative stabilities at high temperatures and pressures

    Science.gov (United States)

    Schulte, Mitchell D.; Shock, Everett L.

    1993-01-01

    Aldehydes are common in a variety of geologic environments and are derived from a number of sources, both natural and anthropogenic. Experimental data for aqueous aldehydes were taken from the literature and used, along with parameters for the revised Helgeson-Kirkham-Flowers (HKF) equations of state, to estimate standard partial molal thermodynamic data for aqueous straight-chain alkyl aldehydes at high temperatures and pressures. Examples of calculations involving aldehydes in geological environments are given, and the stability of aldehydes relative to carboxylic acids is evaluated. These calculations indicate that aldehydes may be intermediates in the formation of carboxylic acids from hydrocarbons in sedimentary basin brines and hydrothermal systems like they are in the atmosphere. The data and parameters summarized here allow evaluation of the role of aldehydes in the formation of prebiotic precursors, such as amino acids and hydroxy acids on the early Earth and in carbonaceous chondrite parent bodies.

  5. Geology of the Early Archean Mid-Ocean Ridge Hydrothermal System in the North Pole Dome, Pilbara Craton, Western Australia

    Science.gov (United States)

    Kitajima, K.; Maruyama, S.

    2007-12-01

    An Archean hydrothermal system in the North Pole Dome, Pilbara Craton is associated with extensive fluid circulation driven by numerous extensional fracture systems and the underlying heat source. The fracture system is now occupied by abundant fine-grained quartz aggregate, hence we call this as silica dikes. Some of the fracture system 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 hydrothermal system must have related to normal fault system 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 hydrothermal fluids into 500-1000 m depth range where metasomatic element exchange between

  6. Geophysical characterization of hydrothermal systems and intrusive bodies, El Chichón volcano (Mexico)

    Science.gov (United States)

    Jutzeler, Martin; Varley, Nick; Roach, Michael

    2011-04-01

    The 1982 explosive eruptions of El Chichón volcano (Chiapas, Mexico) destroyed the inner dome and created a 1-km-wide and 180-m-deep crater within the somma crater. A shallow hydrothermal system was exposed to the surface of the new crater floor and is characterized by an acid crater lake, a geyser-like Cl-rich spring (soap pool), and numerous fumarole fields. Multiple geophysical surveys were performed to define the internal structure of the volcanic edifice and its hydrothermal system. We carried out a high-resolution ground-based geomagnetic survey in the 1982 crater and its surroundings and 38 very low frequency (VLF) transects around the crater lake. A 3-D inversion of the ground-based magnetic data set highlighted three high-susceptibility isosurfaces, interpreted as highly magnetized bodies beneath the 1982 crater floor. Inversion of a digitized regional aeromagnetic map highlighted four major deeply rooted cryptodomes, corresponding to major topographic highs and massive lava dome outcrops outside and on the somma rim. The intracrater magnetic bodies correspond closely to the active hydrothermal vents and their modeled maximum basal depth matches the elevation of the springs on the flanks of the volcano. Position, dip, and vertical extent of active and extinct hydrothermal vents identified by VLF-EM surveys match the magnetic data set. We interpret the shallow lake spring hydrothermal system to be mostly associated with buried remnants of the 550 BP dome, but the Cl-rich soap pool may be connected to a small intrusion emplaced at shallow depth during the 1982 eruption.

  7. Geochemistry of Hydrothermal Fluids and Fe-Mn Crusts From the Logatchev Hydrothermal Field, 15°N at the Mid-Atlantic Ridge: Time Series Study in an Ultramafic System

    Science.gov (United States)

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

    2005-12-01

    Hydrothermal systems at mid-ocean ridges are of special interest concerning the elemental and isotopic input to the oceans and the close relationship between hydrothermal fluids and related ecosystems. Until now, only scarse data are published about the temporal variability of chemical and physicochemical parameters in hydrothermal fields. Changes in salinity, gas and metal concentration, mainly caused by magmatic or tectonic events, have a first order effect on the microbial and faunal association. Within the Special Priority Program 1144, funded by the German Research Foundation DFG, the temporal variability of hydrothermal fluids in an ultramafic environment is investigated at different time scales (within years and thousands of years, respectively). The target area of this work is the Logatchev Field located at the Mid-Atlantic Ridge near 15°N, in a slow-spreading ridge segment dominated by tectonic spreading and characterized by outcrops of serpentinized mantle rocks. The water depth ranges between 2950m and 3050m. Geochemical data obtained for hydrothermal fluids sampled during our first two research cruises in 2004 and 2005 (out of 6 planned), show high concentrations of CH4 and H2, higher concentrations of certain trace metals and a lowered silica concentration, compared to a basaltic system. This signature is caused by the alteration of ultramafic rocks. The fluids show a slightly lowered chlorinity compared to seawater (10-20%), indicating phase separation near the critical point of seawater and the emanation of the vapor phase. Spatial variations in the geochemistry of fluids between different vent sites were observed in samples obtained in 2004. A first evaluation of a temporal variability between 1996 (Douville et al., 2002), 2004 and 2005 show slight changes in the chlorinity, silica, gas, and metal concentrations. Fe-Mn deposits are used for the reconstruction of long-term changes in the Logatchev vent field. They were sampled in different settings

  8. Dynamic drivers of a shallow-water hydrothermal vent ecogeochemical system (Milos, Eastern Mediterranean)

    Science.gov (United States)

    Yücel, Mustafa; Sievert, Stefan; Giovanelli, Donato; Foustoukos, Dionysis; DeForce, Emelia; Thomas, François; Vetriani, Constantino; Le Bris, Nadine

    2014-05-01

    Shallow-water hydrothermal vents share many characteristics with their deep-sea analogs. However, despite ease of access, much less is known about the dynamics of these systems. Here, we report on the spatial and temporal chemical variability of a shallow-water vent system 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 hydrothermal tracers (e.g. Fe2+, FeSaq, Mn2+) on sediment cores taken along a transect in hydrothermally 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 hydrothermal 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 hydrothermally 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

  9. Chemical transport in geothermal systems in Iceland: Evidence from hydrothermal alteration

    Science.gov (United States)

    Franzson, Hjalti; Zierenberg, Robert; Schiffman, Peter

    2008-06-01

    This study focuses on the chemical changes in basaltic rocks in fossil low- and high-temperature hydrothermal systems 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 systems (Hafnarfjall, Geitafell), and the third group from a low temperature, zeolite-altered plateau basalt succession. The results show that hydrothermally 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 systems show quite similar chemical alteration trends, an observation which may apply to Icelandic fresh water high-temperature systems in general. The geochemical data show that the major changes in the altered rocks from Icelandic geothermal systems may be attributed to addition of elements during deposition of pore-filling alteration minerals. A comparison with seawater-dominated basalt-hosted hydrothermal systems shows much greater mass flux within the seawater systems, even though both systems 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 hydrothermal fluids.

  10. Geochemistry and Stable Isotopes of Tacana Volcano-Hydrothermal System, Mexico-Guatemala

    Science.gov (United States)

    Rouwet, D. /; Inguaggiato, S.; Taran, Y. /; Varley, N. /

    2003-12-01

    Tacana volcano (4100 m.s.n.m.), situated on the border between Chiapas (Mexico) and Guatemala is considered an active volcano. In May 1986, after a minor phreatic explosion, a fumarole field was formed at an altitude between 3200 and 3600 m.a.s.l. Around the volcano, at altitudes between 1500 and 2000 m.a.s.l., exist several thermal springs, with temperatures up to 63 degrees C. Incomplete chemical composition of the Agua Caliente thermal waters in the period 1986-1993 were presented by Medina (1986), De la Cruz-Reyna et al. (1989) and Armienta and De la Cruz-Reyna (1995), a chemical analysis of fumarole gases were published by Martini et al. (1986). This study presents the first series of isotope data of water and gases: hydrogen, oxygen, carbon and helium. Data on gas and water chemistry of several thermal spring waters and gases are presented in more detail than ever. Hydrogen and oxygen isotopes of Tacana thermal spring waters show that meteoric water is the main contribution for the thermal waters. Cation geothermometry of the spring waters confirm these meteoric contribution, as all waters are immature in a dynamic system of water-rock interaction with a constant infiltration of fresh meteoric waters (precipitation of 6000 mm per year). The relatively high bicarbonate (up to 1100 ppm) and sulphate (up to 1200 ppm) concentrations in the thermal waters suggest an important degassing up to 2500 m below the volcano summit, which indicates the presence of a extended and complex volcano-hydrothermal system. Helium isotopes of free and dissolved gases confirm the existence of a magmatic contribution, so as for fumarole gases (6.6 R/Ra) as for gases sampled at the thermal springs (5.7-6.2 R/Ra for free gases and between 0.50 and 5.55 R/Ra for dissolved gases). These values are typical for gases liberated at volcanoes in clasic volcanic arcs. The lower values for the dissolved He is probably due to an interaction with the granitic basement, which can be found at

  11. Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

    Science.gov (United States)

    Coco, A.; Gottsmann, J.; Whitaker, F.; Rust, A.; Currenti, G.; Jasim, A.; Bunney, S.

    2016-04-01

    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 hydrothermal 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 hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal 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.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 hydrothermal system, 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 unrest

  12. Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of an active caldera

    Directory of Open Access Journals (Sweden)

    A. Coco

    2015-08-01

    Full Text Available Ground deformation and gravity changes in active 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 hydrothermal 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 hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide. Hydrothermal 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. Based on data for the Campi Flegrei caldera (Italy, a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, 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 unrest, gravity

  13. S/Se ratio of pyrite from eastern Australian VHMS deposits: implication of magmatic input into volcanogenic hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Huston, D.L. [Geological Survey of Canada, Ottawa, ON (Canada); Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience; Cooke, D.R. [Tasmania Univ., Sandy Bay, TAS (Australia)

    1993-12-31

    The proton microprobe was used to determine the concentrations of over twenty trace elements in pyrite grains from four volcanic-hosted massive sulphide (VHMS) deposits in eastern Australia. Of the elements determined, Se has the most potential in resolving important problems in the genesis of this class of ore deposits. This paper summarises analytical conditions, describes the distribution of Se in pyrite in VHMS deposits as determined in this and other studies, discusses the speciation of Se in hydrothermal fluids, and presents a genetic model on the relative contribution of magmatic versus sea water Se (and S) in VHMS systems. 2 refs., 1 fig.

  14. Numerical Modeling of Multiphase Fluid Flow in Ore-Forming Hydrothermal Systems

    Science.gov (United States)

    Weis, P.; Driesner, T.; Coumou, D.; Heinrich, C. A.

    2007-12-01

    Two coexisting fluid phases - a variably saline liquid and a vapor phase - are ubiquitous in ore-forming and other hydrothermal systems. Understanding the dynamics of phase separation and the distinct physical and chemical evolution of the two fluids probably plays a key role in generating different ore deposit types, e.g. porphyry type, high and low sulfidation Cu-Mo-Au deposits. To this end, processes within hydrothermal systems have been studied with a refined numerical model describing fluid flow in transient porous media (CSP~5.0). The model is formulated on a mass, energy and momentum conserving finite-element-finite-volume (FEFV) scheme and is capable of simulating multiphase flow of NaCl-H20 fluids. Fluid properties are computed from an improved equation of state (SOWAT~2.0). It covers conditions with temperatures of up to 1000 degrees~C, pressures of up to 500 MPa, and fluid salinities of 0~to 100%~NaCl. In particular, the new set-up allows for a more accurate description of fluid phase separation during boiling of hydrothermal fluids into a vapor and a brine phase. The geometric flexibility of the FEFV-meshes allows for investigations of a large variety of geological settings, ranging from ore-forming processes in magmatic hydrothermal system to the dynamics of black smokers at mid-ocean ridges. Simulations demonstrated that hydrothermal convection patterns above cooling plutons are primarily controlled by the system-scale permeability structure. In porphyry systems, high fluid pressures develop in a stock rising from the magma chamber which can lead to rock failure and, eventually, an increase in permeability due to hydrofracturing. Comparisons of the thermal evolution as inferred from modeling studies with data from fluid inclusion studies of the Pb-Zn deposits of Madan, Bulgaria are in a strikingly good agreement. This indicates that cross-comparisons of field observations, analytical data and numerical simulations will become a powerful tool towards a

  15. Speciation and Precipitation of Uranium Complexes in Hydrothermal Solutions Related to Granite—type Uranium Deposits

    Institute of Scientific and Technical Information of China (English)

    陈培荣; 章邦桐; 等

    1992-01-01

    Uranium-bearing hydrothermal solutions during the stage of ore deposition are weakly alkaline and of the Ca2+ -Na+/HCO3- -F- type.UO2(CO3)22- and UO2F4-, are dominant in the hydrothermal solutions with respect to their activity.Wall-rock hydrothermal alterations ,temperature and pressure drop and the reducing capability of rock assemblage (Δeh) led to a decrease in Eh of the hydrothermal solutions and an increase in Eh at which uranium began precipitating.Therefore,the mechanism of uranium precipitation is essentially the reduction of uranium complexes.The granite-type uranium deposits are the most important type of uranium resources in China.Discussions will be made in this paper concerning the hydrothermal speciation and precipitation mech-anisms of uranium complexes in the light of fluid inclusion and geological data from some major de-posits of this type in South China.

  16. Geochemistry of the Koshelev Volcano-Hydrothermal System, Southern Kamchatka, Russia

    Science.gov (United States)

    Taran, Y.; Kalacheva, E.

    2015-12-01

    Koshelev is the southernmost volcano of the Kamchatkan volcanic front where magmatic plumbing systems 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 hydrothermal system, 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 system is a typical steam cap with temperature close to 240ºC. Two hydrothermal 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 hydrothermal vapours of the Koshelev system. 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 system is presented and discussed.

  17. The hydrothermal system of the Domuyo volcanic complex (Argentina): A conceptual model based on new geochemical and isotopic evidences

    Science.gov (United States)

    Tassi, F.; Liccioli, C.; Agusto, M.; Chiodini, G.; Vaselli, O.; Calabrese, S.; Pecoraino, G.; Tempesti, L.; Caponi, C.; Fiebig, J.; Caliro, S.; Caselli, A.

    2016-12-01

    The Domuyo volcanic complex (Neuquén Province, Argentina) hosts one of the most promising geothermal systems of Patagonia, giving rise to thermal manifestations discharging hot and Cl--rich fluids. This study reports a complete geochemical dataset of gas and water samples collected in three years (2013, 2014 and 2015) from the main fluid discharges of this area. The chemical and isotopic composition (δD-H2O and δ18O-H2O) of waters indicates that rainwater and snow melting are the primary recharge of a hydrothermal reservoir located at relative shallow depth (400-600 m) possibly connected to a second deeper (2-3 km) reservoir. Reactive magmatic gases are completely scrubbed by the hydrothermal aquifer(s), whereas interaction of meteoric waters at the surface causes a significant air contamination and dilution of the fluid discharges located along the creeks at the foothill of the Cerro Domuyo edifice. Thermal discharges located at relatively high altitude ( 3150 m a.s.l.), namely Bramadora, are less affected by this process, as also shown by their relatively high R/Ra values (up to 6.91) pointing to the occurrence of an actively degassing magma batch located at an unknown depth. Gas and solute geothermometry suggests equilibrium temperatures up to 220-240 °C likely referred to the shallower hydrothermal reservoir. These results, confirming the promising indications of the preliminary surveys carried out in the 1980‧s, provide useful information for a reliable estimation of the geothermal potential of this extinct volcanic system, although a detailed geophysical measurements is required for the correct estimation of depth and dimensions of the fluid reservoir(s).

  18. Numerical modeling of the three-layered hydrothermal system in the Kuju volcanic region, central Kyushu, Japan

    Science.gov (United States)

    Araragi, K.; Ehara, S.; Fujimitsu, Y.

    2008-12-01

    Numerical modeling of hydrothermal systems beneath active volcanoes has been conducted. Their purposes were, however, confined to interpret individual geothermal systems. We constructed a numerical model of the Kuju volcanic region, central Kyushu, Japan using 3-D finite-difference code HYDROTHERM ver.2.2 (Hayba and Ingebritsen, 1994). The central part of Kuju volcano is categorized as an active magmatic hydrothermal system. Otake-Hatchobaru geothermal area, where two geothermal power plants are in operation, is known as a typical liquid dominated hydrothermal system. These two types of geothermal systems are closely located in the region. Moreover, subsurface horizontal temperature distributions in the Kuju volcanic region consist of a three-layered structure. A horizontal temperature anomaly at a depth of -2000m separates into two anomalies at depths of about 0m. Five anomalies appear in the horizontal temperature distribution of 80m depth. Geothermal systems or such characteristics of the thermal structure should be related to the influence of the magma chamber in the region. Existence of molten magma was suggested from seismic observations (Yoshikawa et al., 2005). Therefore, we presumed that the geothermal systems in Otake- Hatchobaru geothermal area and in the central part of Kuju volcano can be explained by a common magma chamber. We determined the calculation time as 40000 based on the age of the latest large pyroclastic flow deposit (Kamata, 1997). The temperature of the magma chamber in the model was maintained at a constant value during the calculation. Parameter studies of crustal permeabilities were conducted to reproduce temperature profiles obtained by logging at shallow depths (NEDO, 1987). The calculated results show that temperature anomalies in the basement rock seemed to be directly affected by the magma chamber. The results also indicate that molten materials have been continuously supplied from the bottom of the magma chamber of Kuju volcano

  19. Solubility limits in Mn–Mg ferrites system under hydrothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hemeda, O.M., E-mail: omhemeda@yahoo.co.uk [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt); Mostafa, N.Y. [Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Faculty of Science, Taif University, PO Box 888, Al-Haweiah, Taif (Saudi Arabia); Abd Elkader, O.H. [Electron Microscope and Thin Films Department, National Research Center, Dokki 12622, Cairo (Egypt); Electron Microscope Unit, Zoology Department, King Saud University, Riyadh 11451 (Saudi Arabia); Ahmed, M.A. [Physics Department, Faculty of Science, Al Azhar University, Nasr City, Cairo (Egypt)

    2014-09-01

    In the present investigation, we successfully synthesized a pure MnFe{sub 2}O{sub 4} ferrite by the hydrothermal method. Moreover, the effect of Mg ion content on the formation of Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} particles (with x varying from 0.1 to 1.0) was also investigated using XRD, SEM, TEM and Mossbauer Spectroscopy. Phases formed in the system Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4}; 0.0≤x≤1.0 were investigated under hydrothermal conditions at 453 K.The produced phases were characterized by X-ray diffraction, Scanning, transmission microscopy and Mossbauer spectroscopy. The information of composition, cation distribution in the spinel structure and the particle size of the products were obtained. The spinel ferrites; Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} were formed in the range 0.0≤x≤0.3. However, sample with x>0.3 showed semi-crystalline magnesium hydroxide (Mg(OH){sub 2}) and hematite (Fe{sub 2}O{sub 3}) beside the ferrite phase. For x=1.0, only magnesium hydroxide and hematite are formed without any ferrites. Particles of uniform size around 10–20 nm were obtained in the spinel structure of Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} with x=0.0 and 0.1. The corresponding average crystallite size for each sample was 40.3 nm and 39.2 nm respectively. In addition, the Mossbauer spectra were analyzed into two subspectra, one for the tetrahedral A-site and the other for the octahedral B-site. The Mossbauer parameters were determined and discussed for the studied system. The cation distribution was estimated from the analysis of the Mossbauer spectra as well as the X-ray diffraction patterns. The results showed that Mg ions occupy mainly B-site while both Mn and Fe ions are distributed between A- and B-sites. - Highlights: • Mossbauer characterization of Mg–Mn ferrite prepared by hydrothermal route. • X-ray powder diffraction analysis of Mg–Mn ferrite prepared by hydrothermal route. • Solubility limit of MgMn ferrite under

  20. A model for Ischia hydrothermal system: Evidences from the chemistry of thermal groundwaters

    Science.gov (United States)

    Di Napoli, R.; Aiuppa, A.; Bellomo, S.; Brusca, L.; D'Alessandro, W.; Candela, E. Gagliano; Longo, M.; Pecoraino, G.; Valenza, M.

    2009-10-01

    Ischia volcano, in Central Italy, has long been known for its copious surface hydrothermal manifestations, signs of a pervasive circulation of hot fluids in the subsurface. Because of the significant chemical heterogeneity of fumarolic gas discharges and hot spring discharges, evidences of a complex hydrothermal setting, a definite model of fluid circulation at depth is currently unavailable, in spite of the several previous efforts. Here, we report on the chemical and isotopic composition of 120 groundwater samples, collected during several sampling surveys from 2002 to 2007. The acquired data suggest that the composition of surface manifestations reflect contributions from meteoric water, sea water, and thermal fluids rising from two distinct hydrothermal reservoir, with equilibrium temperatures of respectively ~ 150 °C and ~ 270 °C, and depths of 150-300 m and > 300 m (but possibly > 1000 m). We also make use of an isotopic characterization of the dissolved gas phase in thermal waters to demonstrate that the Ischia hydrothermal system is currently supplied by a deep-rising gas component (DGC), characterized by CO 2 ~ 97.7 ± 1.2 vol.% (on a water-free basis), δ13C CO2 = - 3.51 ± 0.9‰, and helium isotopic ratio of about 3.5 Ra ( 3He/ 4He ratio normalized to the air ratio, Ra), likely magmatic in origin. An assessment of the thermal budget for Ischia hydrothermal system is also presented, in the attempt to derive a first estimate of the size and rate of degassing of the magmatic reservoir feeding the gas emissions. We calculate that a heat flow of about 153-222 MW presently drives hydrothermal circulation on the island, which we suggest is supplied in convective form (e.g., by the ascent of a high- T magmatic vapour phase) by complete degassing of 2.2-3.3 · 10 7 m 3 yr - 1 of trachytic magma (with ~ 2.1 wt.% dissolved H 2O content). If extrapolated to entire period of quiescence lasting since the Arso eruption in 1302 A.D., this volume corresponds to 1

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

    Science.gov (United States)

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

    2016-05-01

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

  2. High-resolution simulations of multi-phase flow in magmatic-hydrothermal systems with realistic fluid properties

    Science.gov (United States)

    Geiger, S.; Driesner, T.; Matthai, S.; Heinrich, C.

    2002-12-01

    Realistic modelling of multi-phase fluid flow, energy and component transport in magmatic-hydrothermal systems is very challenging because hydrological properties of fluids and rocks vary over many orders of magnitude and the geometric complexities of such systems. Furthermore, density dependent component transport and transient permeability variations due to P-T changes and fluid-rock interactions introduce additional difficulties. As a result, the governing equations for the hydrodynamics, energy and component transport, and thermodynamics in magmatic hydrothermal systems are highly non-linear and strongly coupled. Essential requirements of a numerical formulation for such a system are: (1) a treatment of the hydrodynamics that can accurately resolve complex geological structures and represent the highly variable fluid velocities herein, (2) a realistic thermodynamic representation of the fluid properties including the wide P-T-X range of liquid+vapour coexistence for the highly saline fluids, and (3) an accurate handling of the highly contrasting transport properties of the two fluids. We are combining higher order finite-element (FE) methods with total variation diminishing finite volume (TVDFV) methods to model the hydrodynamics and energy and component transport of magmatic hydrothermal systems. Combined FE and TVDFV methods are mass and shock preserving, yield great geometric flexibility in 2D and 3D [2]. Furthermore, efficient matrix solvers can be employed to model fluid flow in geologically realistic structures [5]. The governing equations are linearized by operator-splitting and solved sequentially using a Picard iteration scheme. We chose the system water-NaCl as a realistic proxy for natural fluids occurring in magmatic-hydrothermal systems. An in-depth evaluation of the available experimental and theoretical data led to a consistent and accurate set of formulations for the PVTXH relations that are valid from 0 to 800 C, 0 to 500 MPa, and 0 to 1 XNa

  3. Post-impact hydrothermal system geochemistry and mineralogy: Rochechouart impact structure, France.

    Science.gov (United States)

    Simpson, Sarah

    2014-05-01

    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 hydrothermal systems to form. Of the 170 known impact structures on Earth, over one-third are known to contain fossil hydrothermal systems [1]. The introduction of water to a system, 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 hydrothermal 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 hydrothermal system, 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 hydrothermal system. 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

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

    Science.gov (United States)

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

    2005-12-01

    Springs area. The test sites represent different structural regimes of the Yellowstone Caldera complex: (a) inner caldera radial faults related to the Sour Creek resurgent dome at GOPA, (b) an extra-caldera regional fault systems in a region where local seismicity appears to be focused to in recent decades (Sylvan), and (c) the caldera rim ring fracture system (Washburn). Flux data on CO2, H2, CO, and H2S were acquired, as well as temperature/depth profiles which yielded soil temperatures, geothermal gradient and heat flux data. The results indicate that at least two populations are present in all four species at all sites, and that the dominant populations of H2 and CO2 appear to be structurally controlled. In contrast, CO and H2S appear to form high-flux clusters around hot pools. The former are explained by a strong influence of deeper processes such as magmatic degassing, while the latter may be explained by more shallow chemical or biological processes. A magmatic signature (high CO2/H2S ratios) is not evident along lineaments but appears localized. High reduced gas fluxes are observed at ground wetted by adjacent thermal pools, and similarly, the ground's thermal budget appears to be strongly controlled by localized conductive heating by thermal waters rather than advective heat transport. These findings provide the context for the organic compounds found in these and other hydrothermal and volcanic gas emissions.

  5. Group Search Optimization for Fixed Head Hydrothermal Power System

    Science.gov (United States)

    Jena, Chitralekha; Basu, Mousumi

    2017-02-01

    This paper presents group search optimization for optimal scheduling of thermal plants in coordination with fixed head hydro units. Numerical results for two test systems 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.

  6. The Magma-Hydrothermal System at Mutnovsky Volcano, Kamchatka Peninsula, Russia

    Directory of Open Access Journals (Sweden)

    Alexey Kiryukhin

    2009-03-01

    Full Text Available What is the relationship between the kinds of volcanoes that ring the Pacific plate and nearby hydrothermal systems? A typical geometry for stratovolcanoes and dome complexes is summit fumaroles and hydrothermal manifestations on and beyond their flanks. Analogous subsurface mineralization is porphyry copper deposits flanked by shallow Cu-As-Au acid-sulfate deposits and base metal veins. Possible reasons for this association are (1 upward and outward flow of magmatic gas and heat from the volcano’s conduit and magma reservoir, mixing with meteoric water; (2 dikes extending from or feeding towards the volcano that extend laterally well beyond the surface edifice, heating a broad region; or (3 peripheral hot intrusions that are remnants of previous volcanic episodes, unrelated to current volcanism. These hypotheses are testable through a Mutnovsky Scientific Drilling Project (MSDP that was discussed in a workshop during the last week of September 2006 at a key example, the Mutnovsky Volcano of Kamchatka. Hypothesis (1 was regarded as the most likely. It is also the most attractive since it could lead to a new understanding of themagma-hydrothermal connection and motivate global geothermal exploration of andesitic arc volcanoes.

  7. Hydrothermal system of the Papandayan Volcano from temperature, self-potential (SP) and geochemical measurements

    Science.gov (United States)

    Byrdina, Svetlana; Revil, André; Gunawan, Hendra; Saing, Ugan B.; Grandis, Hendra

    2017-07-01

    Papandayan volcano in West Java, Indonesia, is characterized by intense hydrothermal activities manifested by numerous fumaroles at three craters or kawah, i.e. Mas, Manuk and Baru. The latter was created after November 2002 phreatic eruption. Since 2011, numerous volcano-tectonic B events are encountered and the volcano was set on alert status on several occasions. The purpose of the present study is to delineate the structure of the summital hydrothermal system from Self-Potential (SP), soil temperature and gas concentrations in the soil (CO2, SO2 and H2S) data. This combination of geophysical and geochemical methods allows identification of the weak permeable zones serving as preferential pathways for hydrothermal circulation and potential candidates to future landslides or flank collapses. This study is an on-going collaborative research project and we plan to conduct electrical resistivity tomography (ERT) and also Induced-Polarization (IP) surveys. Additional data would allow the 3D imaging of the studied area. The IP parameters will be used to characterise and to quantify the degree of alteration of the volcanic rocks as has been shown very recently in the laboratory studies. There are also rocks and soil samples that will undergo laboratory analyses at ISTerre for IP and complex resistivity parameters at the sample scale that will help to interpret the survey results.

  8. Identifying bubble collapse in a hydrothermal system using hidden Markov models

    Science.gov (United States)

    Dawson, P.B.; Benitez, M.C.; Lowenstern, J. B.; Chouet, B.A.

    2012-01-01

    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 hydrothermal 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 hydrothermal 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 hydrothermal system, with the rate of collapse being controlled by surficial temperatures and daytime evaporation rates. copyright 2012 by the American Geophysical Union.

  9. Geochemistry and solute fluxes from volcano-hydrothermal system of Ketoy, Kuril Island arc

    Science.gov (United States)

    Kalacheva, Elena; Taran, Yuri; Voloshina, Ekaterina; Tarasov, Kirill; Kotenko, Tatiana

    2017-04-01

    Ketoy is a volcanic island in the middle of the Kuril Island arc. With an area of ˜70 km2 it consists of two volcanic structures of different ages. The younger Pallas cone (960 m asl) is characterized by a strong fumarolic activity with maximum temperature of 720˚ C (August 2016) and hosts a cold acid crater lake in the summit crater. The older Ketoy cone (1172 m) at the NE of the island is cut by the erosion crater that open to the east and known as a canyon of Gorchichny Stream. There is a strong hydrothermal activity within the canyon with boiling springs and steam vents. We present our data obtained during the fieldwork in August 2016 on the chemical (major and trace elements including REE) and isotopic (H, O, C, S) composition of thermal fluids from both Gorchichny canyon and thermal fields on the slopes of the Pallas cone. Thermal field of the Gorchichny Stream discharges acid Ca-SO4 and near neutral unusual, Cl-poor, Na-Ca-SO4 hot-to-boiling waters with TDS 2-3 g/L. Thermal field of the summit plateau at the base of the Pallas cone discharges acid Ca-SO4 warm water that can be the seepage from the crater lake. Isotopic compositions of thermal waters are close to the meteoric water line but with a clear positive shift in both δ18O and δD with a trend directed to the isotopic composition of condensates of fumarolic gases of the Pallas cone. For the first time the outflow rates of the draining streams have been measured and hydrothermal solute fluxes from the volcano-hydrothermal system have been estimated. The total hydrothermal flux of chloride and sulfate from Ketoy Island is estimated as 8.5 t/d of Cl and 30 t/d of SO4. This work was supported by the RSF grant #15-17-20011.

  10. Seismic Tomography and Monitoring of Magmatic Geothermal and Natural Hydrothermal Systems in the South of Bandung, Indonesia

    OpenAIRE

    P. Jousset; R. Sule; W. Diningrat; Devy Kamil Syahbana; Alexandra Gassner; F. Akbar; Sebastien Guichard; Nicole Schuck; R. Ryannugroho; Andri Hendriyana; Y. Kusnadi; A. Nugraha; U. Muksin; M. Jaya; B. Pratomo

    2015-01-01

    We assess geothermal resources from our understanding of the structure and the dynamics of geothermal reservoirs and hydrothermal systems 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 hydrothermal processes in this area. We deployed a geophysical network starting with a network of 30 seismic stations including...

  11. Characterization of the Hydrothermal System of the Tinguiririca Volcanic Complex, Central Chile, using Structural Geology and Passive Seismic Tomography

    Science.gov (United States)

    Pavez Orrego, Claudia; Tapia, Felipe; Comte, Diana; Gutierrez, Francisco; Lira, Elías; Charrier, Reynaldo; Benavente, Oscar

    2016-04-01

    A structural characterization of the hydrothermal-volcanic field associated with the Tinguiririca Volcanic Complex had been performed by combining passive seismic tomography and structural geology. This complex corresponds to a 20 km long succession of N25°E oriented of eruptive centers, currently showing several thermal manifestations distributed throughout the area. The structural behavior of this zone is controlled by the El Fierro - El Diablo fault system, corresponding to a high angle reverse faults of Oligocene - Miocene age. In this area, a temporary seismic network with 16 short-period stations was setup from January to April of 2010, in the context of the MSc thesis of Lira- Energía Andina (2010), covering an area of 200 km2 that corresponds with the hydrothermal field of Tinguiririca Volcanic Complex (TVC), Central Chile, Southern Central Andes. Using P- and S- wave arrival times, a 3D seismic velocity tomography was performed. High Vp/Vs ratios are interpreted as zones with high hot fluid content and high fracturing. Meanwhile, low Vp/Vs anomalies could represent the magmatic reservoir and the conduit network associated to the fluid mobility. Based on structural information and thermal manifestations, these anomalies have been interpreted. In order to visualize the relation between local geology and the velocity model, the volume associated with the magma reservoir and the fluid circulation network has been delimited using an iso-value contour of Vp/Vs equal to 1.70. The most prominent observed feature in the obtained model is a large "V" shaped low - velocity anomaly extending along the entire study region and having the same vergency and orientation as the existing high-angle inverse faults, which corroborates that El Fierro - El Diablo fault system represents the local control for fluid mobility. This geometry coincides with surface hydrothermal manifestations and with available geochemical information of the area, which allowed us to generate a

  12. CO 2 degassing and trapping during hydrothermal cycles related to Gondwana rifting in eastern Australia

    Science.gov (United States)

    Uysal, I. Tonguç; Golding, Suzanne D.; Bolhar, Robert; Zhao, Jian-xin; Feng, Yue-xing; Baublys, Kim A.; Greig, Alan

    2011-10-01

    Intensive carbonate and clay mineral authigenesis took place throughout the Late Permian Bowen-Gunnedah-Sydney basin system in eastern Australia. We conducted isotopic and trace element analyses of carbonate and clay minerals from clastic sedimentary rocks of the Gunnedah Basin and the Denison Trough in the Bowen Basin. Rb-Sr isochron age data of the illitic clays are consistent with episodic hydrothermal fluid flow events that occurred in association with Gondwana rifting accompanied by alkaline magmatism at ˜85 Ma and ˜95 Ma. Stable isotope data of carbonate and clay minerals from the Gunnedah Basin are indicative of meteoric waters from a high-latitude environment as the main fluid source, whereas trace element, Sr and Nd isotope data highlight mixing of meteoric fluids with magmatic and/or crustal components, with a possible input from marine carbonates for some samples. Trace metals, oxygen and strontium isotopes of dawsonites from the Denison Trough are interpreted to have been mobilised by fluids that interacted with evolved clastic sedimentary and marine carbonate end members. According to the carbon isotope data, CO 2 for calcite and ankerite precipitation was sourced mainly from thermal degradation of organic matter and magmatism, whereas the CO 2 used for dawsonite formation is inferred to have been derived from magmatic and marine sources. In the low permeability environments (particularly in coal seams), the increasing accumulation and oversaturation of CO 2 particularly promote the precipitation of dawsonite.

  13. Geochemistry of Precambrian carbonates. I - Archean hydrothermal systems

    Science.gov (United States)

    Veizer, Jan; Hoefs, Jochen; Ridler, R. H.; Jensen, L. S.; Lowe, D. R.

    1989-04-01

    Carbonate rocks from the Superior Province and the Slave Province of Canada, Kaapvaal Craton of South Africa, and the Pilbara Block of Australia were characterized mineralogically, isotopically, and chemically. Result on the bulk chemical composition suggest that the carbonate rocks originated by massive carbonatization, silicification, and sericitization via replacement and/or filling of void spaces of intermediate to ultramafic protoliths. Trace element chemistry of carbonates was found to be consistent with their precipitation from relatively low-salinity solutions and with the derivation of solutes from the contemporaneous volcano-sedimentary piles. On the basis of mineralogy and the chemical and isotopic findings, it is suggested that the carbonate component defines two partially overlapping populations, a ferroan dolomite-breunnerite series restricted mostly to extensive faults and shear zones, and a calcite-ferroan dolomite-siderite population associated with alteration halos of a larger regional extent.

  14. Hydrothermal organic synthesis experiments

    Science.gov (United States)

    Shock, Everett L.

    1992-01-01

    Ways in which heat is useful in organic synthesis experiments are described, and experiments on the hydrothermal 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 hydrothermal conditions is a distinct possibility. However, carefully controlled experiments which replicate the descriptive variables of natural hydrothermal systems have not yet been conducted with the aim of testing the hypothesis of hydrothermal organic systems.

  15. Emerald mineralization and metasomatism of amphibolite, khaltaro granitic pegmatite - Hydrothermal vein system, Haramosh Mountains, Northern Pakistan

    Science.gov (United States)

    Laurs, B.M.; Dilles, J.H.; Snee, L.W.

    1996-01-01

    single fluid of magmatic origin with ??18OH2O = 8??? produced the pegmatite-vein system and hydrothermal alteration at temperatures between 550 and 400??C. The formation of emerald results from introduction of HF-rich magmatic-hydrothermal fluids into the amphibolite, which caused hydrogen ion metasomatism and released Cr and Fe into the pegmatite-vein system.

  16. Hydrothermal Conditions and the Origin of Cellular Life.

    Science.gov (United States)

    Deamer, David W; Georgiou, Christos D

    2015-12-01

    The conditions and properties of hydrothermal vents and hydrothermal fields are compared in terms of their ability to support processes related to the origin of life. The two sites can be considered as alternative hypotheses, and from this comparison we propose a series of experimental tests to distinguish between them, focusing on those that involve concentration of solutes, self-assembly of membranous compartments, and synthesis of polymers. Key Word: Hydrothermal systems.

  17. Chemical, isotopic, and dissolved gas compositions of the hydrothermal system in Twin Falls and Jerome counties, Idaho

    Science.gov (United States)

    Mariner, R.H.; Young, H.W.; Evans, ans; Parliman, D.J.

    1991-01-01

    The chemical, isotopic, and gas compositions of the hydrothermal system in Twin Falls and Jerome counties, Idaho, change systematically as the water moves northward from the Idaho-Nevada boundary toward the Snake River. Sodium, chloride, fluoride, alkalinity, dissolved helium, and carbon-13 increase as calcium and carbon-14 decrease. Water-rock reactions may result in dissolution of plagioclase or volcanic glass and calcite, followed by precipitation of zeolites and clays. On the basis of carbon-14 age dating, apparent water ages range from 2,000 to more than 26,000 years; most apparent ages range from about 4,000 to 10,000 years. The older waters, north of the Snake River, are isotopically depleted in deuterium and are enriched in chloride relative to waters to the south. Thermal waters flowing northward beneath the Snake River may join a westward flow of older thermal water slightly north of the river. The direction of flow in the hydrothermal system seems to parallel the surface drainage.

  18. The hydrothermal system of Volcan Puracé, Colombia

    Science.gov (United States)

    Sturchio, Neil C.; Williams, Stanley N.; Sano, Yuji

    1993-05-01

    This paper presents chemical and isotopic data for thermal waters, gases and S deposits from Volcan Puracé (summit elevation ˜4600 m) in SW Colombia. Hot gas discharges from fumaroles in and around the summit crater, and thermal waters discharge from three areas on its flanks. The waters from all areas have δD values of-75±1, indicating a single recharge area at high elevation on the volcano. Aircorrected values of3He/4He in thermal waters range from 3.8 to 6.7 RA, and approach those for crater fumarole gas (6.1 7.1 RA), indicating widespread addition of magmatic volatiles. An economic S deposit (El Vinagre) is being mined in the Rio Vinagre fault zone at 3600 m elevation. Sulfur isotopic data are consistent with a magmatic origin for S species in thermal waters and gases, and for the S ore deposit. Isotopic equilibration between S species may have occurred at 220±40°C, which overlaps possible equilibration temperatures (170±40°C) determined by a variety of other geothermometers for neutral thermal waters. Apparent CH4-CO2 equilibration temperatures for gases from thermal springs (400±50°C) and crater fumaroles (520±60°C) reflect higher temperatures deeper in the system. Hot magmatic gas ascending through the Rio Vinagre fault zone is though to have precipitated S and generated thermal waters by interaction with descending meteoric waters.

  19. Mechanical behaviour of the Krafla geothermal reservoir: Insight into an active magmatic hydrothermal system

    Science.gov (United States)

    Eggertsson, Guðjón H.; Lavallée, Yan; Kendrick, Jackie E.

    2017-04-01

    Krafla volcano, located in North-East Iceland, holds an active magmatic hydrothermal system. Since 1978, this system has been exploited for geothermal energy. Today it is exploited by Landsvirkjun National Power of Iceland and the system is generating 60 MWg from 18 wells, tapping into fluids at 200-300°C. In order to meet further demands of environmentally sustainable energy, Landsvirkjun aims to drill deeper and source fluids in the super-heated, super high-enthalpy system which resides deeper (at 400-600°C). In relation to this, the first well of the Icelandic Deep Drilling Project (IDDP) was drilled in Krafla in 2009. Drilling stopped at a depth of 2.1 km, when the drill string penetrated a rhyolitic magma body, which could not be bypassed despite attempts to side-track the well. This pioneering effort demonstrated that the area close to magma had great energy potential. Here we seek a constraint on the mechanical properties of reservoir rocks overlying the magmatic systems to gain knowledge on these systems to improve energy extraction. During two field surveys in 2015 and 2016, and through information gathered from drilling of geothermal wells, five main rock types were identified and sampled [and their porosities (i.e., storage capacities) where determined with a helium-pycnometer]: basalts (5-60% porosity), hyaloclastites (geothermal reservoir. Uniaxial and triaxial compressive strength tests have been carried out, as well as indirect tensile strength tests using the Brazilian disc method, to measure the rock strengths. The results show that the rock strength is inversely proportional to the porosity and strongly affected by the abundance of microcracks; some of the rocks are unusually weak considering their porosities, especially at low effective pressure as constrained at Krafla. The results also show that the porous lithologies may undergo significant compaction at relatively low loads (i.e., depth). Integration of the observed mechanical behaviour and

  20. Numerical Modeling of Brine Formation and Serpentinization at the Rainbow Hydrothermal System

    Science.gov (United States)

    Sekhar, P.; Lowell, R. P.

    2015-12-01

    The Rainbow hydrothermal field on the Mid Atlantic Ridge is a high-temperature hydrothermal system hosted in peridotite. The vent fluids are rich in methane and hydrogen suggesting that serpentinization is occurring at depth in the system. 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 hydrothermal fluid, we construct a 2D numerical model of two-phase hydrothermal 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 system depths of 2 and 1 km, respectively. The brine-derived fluid from the deeper system barely exceeds seawater, whereas the shallower system produces a short pulse of 9.0 wt% for 5 years. We then consider 1 km deep systems 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 system and will provide insight into methane flux in the Rainbow vent field.

  1. Multifractal spatial organisation in hydrothermal gold systems of the Archaean Yilgarn craton, Western Australia

    Science.gov (United States)

    Munro, Mark; Ord, Alison; Hobbs, Bruce

    2015-04-01

    A range of factors controls the location of hydrothermal 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 hydrothermal systems 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 hydrothermal gold systems 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

  2. Geochemistry of the hydrothermal systems in the Jujuy Province, Argentina, and relationship with the regional geology

    Science.gov (United States)

    Peralta Arnold, Yesica; Cabassi, Jacopo; Tassi, Franco; Caffe, Pablo; Vaselli, Orlando

    2016-04-01

    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 hydrothermal 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 System. 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 System, the Aguas Calientes springs are characterized by low temperature (from 21°C to

  3. A multi-faceted approach to characterize acid-sulfate alteration processes in volcanic hydrothermal systems on Earth and Mars

    Science.gov (United States)

    Marcucci, Emma Cordts

    Acid-sulfate alteration is a dominant weathering process in high temperature, low pH, sulfur-rich volcanic environments. Additionally, hydrothermal environments have been proposed as locations where life could have originated on Earth. Based on the extensive evidence of flowing surface water and persistent volcanism, similar locations and processes could have existed on early Mars. Globally observed alteration mineral assemblages likely represent relic Martian hydrothermal settings. Yet the limited understanding of environmental controls, limits the confidence of interpreting the paleoconditions of these hydrothermal systems and assessing their habitability to support microbial life. This thesis presents a series of laboratory experiments, geochemical models, analog fieldwork, and Martian remote sensing to characterize distinguishing features and controls of acid-sulfate alteration. The experiments and models were designed to replicate alteration is a highly acidic, sulfurous, and hot field sites. The basaltic minerals were individually reacted in both experimental and model simulations with varying initial parameters to infer the geochemical pathways of acid-sulfate alteration on Earth and Mars. It was found that for a specific starting material, secondary mineralogies were consistent. Variations in pH, temperature and duration affected the abundance, shape, and size of mineral products. Additionally evaporation played a key role in secondary deposits; therefore, both alteration and evaporitic processes need to be taken into consideration. Analog volcanic sites in Nicaragua were used to supplement this work and highlight differences between natural and simulated alteration. In situ visible near-infrared spectroscopy demonstrated that primary lithology and gas chemistry were dominant controls of alteration, with secondary effects from environmental controls, such as temperature and pH. The spectroscopic research from the field was directly related to Mars

  4. Multiple objective optimization of hydro-thermal systems using Ritz's method

    Directory of Open Access Journals (Sweden)

    L. Bayón Arnáu

    2000-01-01

    Full Text Available This paper examines the applicability of the Ritz method to multi-objective optimization of hydro-thermal systems. The algorithm proposed is aimed to minimize an objective functional that incorporates the cost of energy losses, the conventional fuel cost and the production of atmospheric emissions such as NOx and SO2 caused by the operation of fossil-fueled thermal generation. The formulation includes a general layout of hydro-plants that may form multi-chains of reservoir network.

  5. Methodology of determining the uncertainty in the accessible geothermal resource base of identified hydrothermal convection systems

    Science.gov (United States)

    Nathenson, Manuel

    1978-01-01

    In order to quantify the uncertainty of estimates of the geothermal resource base in identified hydrothermal convection systems, 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 system or in many systems, 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 system, 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 systems, the central limit approximation is shown to give results ranging from good to poor.

  6. Mexican-American Cooperative Program at the Cerro Prieto geothermal field: Analysis of the Nuevo Leon magnetic anomaly and its possible relation to the Cerro Prieto magmatic-hydrothermal system

    Science.gov (United States)

    Goldstein, N. E.; Wilt, M. J.; Corrigan, D. J.

    1982-10-01

    The broad dipolar magnetic anomaly whose positive peak is centered near Ejido Nuevo Leon, some 5 km east of the Cerro Prieto I Power Plant, has long been suspended to have a genetic relationship to the thermal source of the Cerro Prieto geothermal system. This suspicion was reinforced after several deep geothermal wells, drilled to depths of 3 to 3.5 km over the anomaly, intersected an apparent dike-sill complex consisting mainly of diabase but with minor rhyodacite. A detailed fit of the observed magnetic field to a computer model indicates that the source may be approximated by a tabular block 4 by 6 km in area, 3.7 km in depth, 2.3 km thick, and dipping slightly to the north. Mafic dike chips from one well, NL-1, were analyzed by means of electron microprobe analyses which showed them to contain a titanomagnetite that is paramagnetic at in-situ temperature conditions. As the dike mineralogy does not account for the magnetic anomaly, the magnetic source is believed to be a deeper, magnetite-rich assemblage of periodotite-gabbro plutons.

  7. Newly discovered hydrothermal system on the Alarcón Rise, Mexico

    Science.gov (United States)

    Paduan, J. B.; Clague, D. A.; Caress, D. W.; Lundsten, L.; Martin, J. F.; Nieves-Cardoso, C.

    2012-12-01

    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 hydrothermal 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 system. The northern field, Ja sít, is a broad cluster of 8 active chimneys (also confirmed) rising above the sheet flow's channel system, 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

  8. Metasomatizing effects of serpentinization-related hydrothermal fluids in abyssal peridotites: new contributions from Hyblean peridotite xenoliths (southeastern Sicily)

    Science.gov (United States)

    Manuella, Fabio Carmelo; Ottolini, Luisa; Carbone, Serafina; Scavo, Lidia

    2016-11-01

    We studied a partially serpentinized peridotite xenolith, found in the diatreme tuff-breccia deposit at Valle Guffari (Hyblean Plateau, southeastern Sicily, Italy), which is representative of the Hyblean peridotite xenolith suite. We also considered all published (21) whole-rock analyses of Hyblean peridotites, to investigate the metasomatizing effects of seawater-related hydrothermal fluids in the Hyblean basement, an in-situ remnant of the ultraslow-spreading Permian Tethys. In detail, we analyzed the serpentine veins by different techniques (scanning electron microscopy-SEM, electron-probe microanalysis-EPMA, micro-Raman spectroscopy, X-ray powder diffraction-XRPD) to determine the crystal-chemical composition and the structure of the veins. In addition, secondary ion mass spectrometry (SIMS) was applied to measure the abundance of trace elements. Serpentine veins are made up of two Fe-rich polytypes, chrysotile 2Mc1 and lizardite 1T. The chondrite-normalized rare earth element compositions of both serpentine polytypes are lower than 1, except for a modest light rare earth element (LREE) enrichment, and also in some fluid-mobile elements (FME: B, Rb, Sr, U). Conversely, the whole-rock composition of the studied peridotite xenolith is enriched with LREE and other trace elements (B, Sr, P, Th, U, Pb), like most Hyblean peridotites. The REE and multi-element patterns of Hyblean peridotites are akin to those of hydrothermal sediments from the Mid-Atlantic Ridge and St. Demetrio hill (northern Hyblean Plateau), and abyssal peridotites (serpentinites) whose trace element abundance is generally ascribed to melt-rock interaction. The integrated interpretation of the data and the documentation of hydrothermal minerals [(Na,S)-rich apatite, carbonates] in serpentine veins indicate that serpentinization-related hydrothermal fluids do have a primary role in metasomatism (mainly for the abundance of LREE and high field strength elements-HFSE) of ancient (Permian Tethys) and

  9. Insight from Genomics on Biogeochemical Cycles in a Shallow-Sea Hydrothermal System

    Science.gov (United States)

    Lu, G. S.; Amend, J.

    2015-12-01

    Shallow-sea hydrothermal ecosystems are dynamic, high-energy systems 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 hydrothermal system offshore Paleochori Bay, Milos, Greece, which is characterized by a central vent covered by white microbial mats with hydrothermally 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 hydrothermal 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

  10. The origin of life near deep-sea hydrothermal systems during the Cambrian explosion: data from the Kyzyl Tashtyg sulphide deposit (Central Asia)

    Science.gov (United States)

    Simonov, Vladimir; Terleev, Alexander; Safonova, Inna; Kotlyarov, Alexey; Stupakov, Sergey; Tokarev, Dmitry

    2015-04-01

    On Earth the solar radiation and the hydrothermal circulation both affect life evolution. Recent extensive studies of the World Ocean have shown that the biodiversity of Earth is linked with hydrothermal activity on the oceanic floor. These deep-sea ecosystems use chemical energy, not solar radiation. In the last quarter of the XX century, a new type of hydrothermal systems, so-called black smokers, was discovered in mid-oceanic ridges. As black smokers form sulfide ores and are surrounded by abundant bio-oases or symbioses, identification of their analogues in ancient orogenic belts is necessary for studying life origin and evolution. Of special importance are problems of life associated with deep-sea hydrothermal systems acted at the Precambrian-Cambrian boundary - the time of Cambrian explosion (Maruyama et al., 2013). During that explosion life significantly evolved and diversified due to dramatic changes of Earth's environment. Consequently, the early Cambrian - late Precambrian Kyzyl Tashtyg sulphide deposit of East Tuva in the Central Asian Orogenic Belt is of special interest. This deposit was formed on the bottom of ancient back-arc deep-sea basin as a result of black smoker hydrothermal activity and is hosted by volcanogenic-sedimentary rocks altered by the high temperature solutions. The altered Kyzyl Tashtyg basalts have an amygdules (filled by albite, epidote and carbonates), contain brown-green microfossils, often attached to their walls. The microfossils are thin tubes 5 to 25 microns in diameter and 500 microns long. This tubes are empty and have straight, curved or branching shape. Chemically, the tube material is close to epidote. In consideration of microscopic dimensions, simple morphology and similarity with modern tubular microorganisms, the studied tube-shaped microfossils can be related to cyanobacteria. Almost the same fossils, associated with oceanic basalt complexes, were described earlier (Furnes et al., 2007; Mcloughlin et al., 2007

  11. Geochemistry of the volcano-hydrothermal system of El Chichón Volcano, Chiapas, Mexico

    Science.gov (United States)

    Taran, Yuri; Fischer, Tobias P.; Pokrovsky, Boris; Sano, Yuji; Armienta, Maria Aurora; Macias, Jose Luis

    The 1982 eruption of El Chichón volcano ejected more than 1km3 of anhydrite-bearing trachyandesite pyroclastic material to form a new 1-km-wide and 300-m-deep crater and uncovered the upper 500m of an active volcano-hydrothermal system. Instead of the weak boiling-point temperature fumaroles of the former lava dome, a vigorously boiling crater spring now discharges / 20kg/s of Cl-rich ( 15 000mg/kg) and sulphur-poor ( / 200mg/kg of SO4), almost neutral (pHup to 6.7) water with an isotopic composition close to that of subduction-type magmatic water (δD=-15‰, δ18O=+6.5‰). This spring, as well as numerous Cl-free boiling springs discharging a mixture of meteoric water with fumarolic condensates, feed the crater lake, which, compared with values in 1983, is now much more diluted ( 3000mg/kg of Cl vs 24 030mg/kg), less acidic (pH=2.6 vs 0.56) and contains much lower amounts of S ( / 200mg/kg of SO4, vs 3550mg/kg) with δ34S=0.5-4.2‰ (+17‰ in 1983). Agua Caliente thermal waters, on the southeast slope of the volcano, have an outflow rate of approximately 100kg/s of 71 °C Na-Ca-Cl water and are five times more concentrated than before the eruption (B. R. Molina, unpublished data). Relative N2, Ar and He gas concentrations suggest extensional tectonics for the El Chichón volcanic centre. The 3He/4He and 4He/20Ne ratios in gases from the crater fumaroles (7.3Ra, 2560) and Agua Caliente hot springs (5.3Ra, 44) indicate a strong magmatic contribution. However, relative concentrations of reactive species are typical of equilibrium in a two-phase boiling aquifer. Sulphur and C isotopic data indicate highly reducing conditions within the system, probably associated with the presence of buried vegetation resulting from the 1982 eruption. All Cl-rich waters at El Chichón have a common source. This water has the appearence of a "partially matured" magmatic fluid: condensed magmatic vapour neutralized by interaction with fresh volcaniclastic deposits and depleted in S

  12. Evolution of the Vesuvius magmatic-hydrothermal system before the 16 December 1631 eruption

    Science.gov (United States)

    Principe, Claudia; Marini, Luigi

    2008-04-01

    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 system 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-hydrothermal systems. 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-hydrothermal-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.

  13. Response of hydrothermal system to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise

    Science.gov (United States)

    Taira, Taka'aki; Brenguier, Florent

    2016-10-01

    Time-lapse monitoring of seismic velocity at volcanic areas can provide unique insight into the property of hydrothermal and magmatic fluids and their temporal variability. We established a quasi real-time velocity monitoring system by using seismic interferometry with ambient noise to explore the temporal evolution of velocity in the Lassen Volcanic Center, Northern California. Our monitoring system 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 hydrothermal system is marked by high-pressurized hydrothermal 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 hydrothermal fluid diffusion that leads to an increase of opening of cracks and subsequently reductions of seismic velocity. We infer that heated-hydrothermal 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.

  14. Microbial heterotrophy coupled to Fe-S-As cycling in a shallow-sea hydrothermal system

    Science.gov (United States)

    Lu, G.; Amend, J.

    2013-12-01

    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 hydrothermal vent systems 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 systems. The aim of this study is to establish links between microbial distribution and in situ Fe-S-As cycling processes in a shallow-sea hydrothermal vent system. We investigated three shallow-sea hydrothermal 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 hydrothermal system. Several autotrophic and heterotrophic media at two pHs (5.5 and 8

  15. Thermal mapping: the hydrothermal system of a volcano used to map faults and palaeostructures within stratified ground. The Yasur-Yenkahe volcanic complex (Vanuatu)

    Science.gov (United States)

    Amin Douillet, Guilhem; Peltier, Aline; Finizola, Anthony; Brothelande, Elodie; Garaebiti, Esline

    2014-05-01

    Subsurface thermal measurements provide a valuable tool to map hydrothermal-fluid release zones in activevolcanic areas. On explosive volcanoes, where ash fall layers deposit parallel to the ground surface, hydrothermal fluids are trapped in the stratification due to the variations in permeability in deposits of the different explosive phases. Thermal fluids thus travel parallel to the surface close to the ground. This horizontal flux can only escape when faults break the seals of stratification. On the Yasur-Yenkahe volcanic complex (Tanna Island, Vanuatu archipelago), fumaroles andhot springs abound, signs of upraising heat fluxes associated to a well-developed hydrothermal activity. Combinationof high resolution mapping of ground thermal anomalies with geomorphological analysis allows thecharacterization of the structural relationships between the active Yasur volcano and the Yenkahe resurgent dome. A complex system of heat release and hydrothermal fluid circulation below the Yasur-Yenkahe complex isevidenced. Circulation, though propagating vertically as a whole, is funneled by stratification. Thus, the main thermal fluid release is almost exclusively concentrated along structural limits that break the seals inducedby the stratified nature of the ground. Three types of medium/high temperature anomalies have beenevidenced: (1) broad hydrothermalized areas linked with planar stratification that favor lateral spreading,(2) linear segments that represent active faults, and (3) arcuate segments related to paleo-crater rims. Thelimit between the Yasur volcano and the Yenkahe resurgent dome is characterized by an active fault systemaccommodating both the rapid uplift of the Yenkahe block and the overloading induced by the volcanoweight. In such a setting, faults converge below the cone of Yasur, which acts as a focus for the faults. Evidenceof such structures, sometimes hidden in the landscape but detected by thermal measurements, iscritical for risk assessment of

  16. Implementation of network flow programming to the hydrothermal coordination in an energy management system

    Energy Technology Data Exchange (ETDEWEB)

    Chaoan Li; Jap, P.J.; Streiffert, D.L. (ESCA Corp., Bellevue, WA (United States))

    1993-08-01

    Hydrothermal Coordination (HTC), consisting of hydro optimization and thermal unit commitment, is a major function in a power system for allocating its generating resources to achieve the system'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 system 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.

  17. Airborne Magnetic and Electromagnetic Data map Rock Alteration and Water Content at Mount Adams, Mount Baker and Mount Rainier, Washington: Implications for Lahar Hazards and Hydrothermal Systems

    Science.gov (United States)

    Finn, C. A.; Deszcz-Pan, M.; Horton, R.; Breit, G.; John, D.

    2007-12-01

    High resolution helicopter-borne magnetic and electromagnetic (EM) data flown over the rugged, ice-covered, highly magnetic and mostly resistive volcanoes of Mount Rainier, Mount Adams and Mount Baker, along with rock property measurements, reveal the distribution of alteration, water and hydrothermal fluids that are essential to evaluating volcanic landslide hazards and understanding hydrothermal systems. Hydrothermally altered rocks, particularly if water saturated, can weaken stratovolcanoes, thereby increasing the potential for catastrophic sector collapses that can lead to far-traveled, destructive debris flows. Intense hydrothermal alteration significantly reduces the magnetization and resistivity of volcanic rock resulting in clear recognition of altered rock by helicopter magnetic and EM measurements. Magnetic and EM data, combined with geological mapping and rock property measurements, indicate the presence of appreciable thicknesses of hydrothermally altered rock west of the modern summit of Mount Rainier in the Sunset Amphitheater region, in the central core of Mount Adams north of the summit, and in much of the central cone of Mount Baker. We identify the Sunset Amphitheater region and steep cliffs at the western edge of the central altered zone at Mount Adams as likely sources for future debris flows. In addition, the EM data identified water-saturated rocks in the upper 100-200 m of the three volcanoes. The water-saturated zone could extend deeper, but is beyond the detection limits of the EM data. Water in hydrothermal fluids reacts with the volcanic rock to produce clay minerals. The formation of clay minerals and presence of free water reduces the effective stress, thereby increasing the potential for slope failure, and acts, with entrained melting ice, as a lubricant to transform debris avalanches into lahars. Therefore, knowing the distribution of water is also important for hazard assessments. Finally, modeling requires extremely low

  18. Isotope hydrology of El Chichón volcano-hydrothermal system; a coupled system of crater lake and hot springs

    Science.gov (United States)

    Peiffer, L.; Taran, Y.; Rouwet, D.

    2010-12-01

    The catastrophic 1982 eruption of El Chichón (>1.5 km3 of erupted material) opened the upper hundred meters of the existing volcano-hydrothermal system. In the new formed 200m-deep crater a large shallow crater lake and numerous hot springs were formed. The lake existence and its salinity depend on the precipitation (~4000 mm/y) as well as a group of geyser-like neutral saline springs (source of Cl and SO4) and hydrothermal steam vents discharging into the lake (source of SO4). The chemistry of these “Soap Pool” (SP) springs evolved from >13,000 ppm of Cl in 1995 to ~2000-3000 ppm of Cl in 2006. Since 2006, this Cl-concentration in SP waters is constant. Similar concentrations of Cl are observed in most flank hot springs located at altitudes of ~ 600 m asl, 2-3 km from the crater. Therefore, it can be suggested that the flank springs, crater lake and crater hot springs are manifestations of the upper, relatively shallow volcano-hydrothermal system developed beneath the crater in the volcano edifice. Water isotopic composition of all types of thermal and fresh waters including fumarolic steam condensates (>100 samples collected in 1995-2010) allow to classify and distinguish different processes of shallow mixing, boiling, evaporation and water-rock isotope exchange. All spring waters from the upper system have meteoric origin, with the isotopic composition plotting close to the meteoric water line. Crater waters are strongly evolved due to shallow boiling and loss of steam. Isotopic composition of water from the lower, deep hydrothermal system is characterized by a significant positive oxygen isotopic shift and a strong Cl-d18O linear correlation. Waters from numerous cold springs that drain pyroclastic deposits demonstrate a clear negative oxygen shift. Some problems related to water isotopic composition are still remain unresolved: (1) we cannot find any traces of the infiltrated isotopically heavy lake waters, i.e., the seepage from the lake at the volcano

  19. On the Interaction of a Vigorous Hydrothermal System with an Active Magma Chamber: The Puna Magma Chamber, Kilauea East Rift, Hawaii

    Science.gov (United States)

    Gregory, R. T.; Marsh, B. D.; Teplow, W.; Fournelle, J.

    2009-12-01

    The extent of the interaction between hydrothermal systems and active magma chambers has long been of fundamental interest to the development of ore deposits, cooling of magma chambers, and dehydration of the subducting lithosphere. As volatiles build up in the residual magma in the trailing edge of magmatic solidification fronts, is it possible that volatiles are transferred from the active magma to the hydrothermal system and vice versa? Does the external fracture front associated with vigorous hydrothermal systems sometimes propagate into the solidification front, facilitating volatile exchange? Or is the magma always sealed at temperatures above some critical level related to rock strength and overpressure? The degree of hydrothermal interaction in igneous systems is generally gauged in post mortem studies of δ18O and δD, where it has been assumed that a fracture front develops about the magma collapsing inward with cooling. H.P. Taylor and D. Norton's (1979; J. Petrol.)seminal work inferred that rocks are sealed with approach to the solidus and there is little to no direct interaction with external volatiles in the active magma. In active lava lakes a fracture front develops in response to thermal contraction of the newly formed rock once the temperature drops to ~950°C (Peck and Kinoshita,1976;USGS PP935A); rainfall driven hydrothermal systems flash to steam near the 100 °C isotherm in the solidified lake and have little effect on the cooling history (Peck et al., 1977; AJS). Lava lakes are fully degassed magmas and until the recent discovery of the Puna Magma Chamber (Teplow et al., 2008; AGU) no active magma was known at sufficiently great pressure to contain original volatiles. During the course of routine drilling of an injection well at the Puna Geothermal Venture (PGV) well-field, Big Island, Hawaii, a 75-meter interval of diorite containing brown glass inclusions was penetrated at a depth of 2415 m, continued drilling to 2488 m encountered a melt

  20. Hydrothermal research and development assessment. Task force report: projections for electric systems

    Energy Technology Data Exchange (ETDEWEB)

    1982-05-01

    It is estimated that high temperature (greater than 150/sup 0/C or 300/sup 0/F) hydrothermal resources in the western United States have the potential for producing about 140,000 megawatts of electric power for 30 years. The objectives of the present analysis were to realistically evaluate the extent to which these resources might be utilized over the next 20 years, and to assess the probably impact of Federal programs on that utilization. The R and D assessment team interviewed industry personnel to determine the nature and the relative significance of investment decision criteria for developers and utilities. The results of these interviews were used to develop a probabilistic model to simulate the investment decision behavior of these two groups toward hydrothermal resources. Estimations of the characteristics of anticipated available resources (e.g., temperature, salinity, depth) and predictions of the geographic distribution of new resource discoveries were based upon the characteristics and distribution of known reservoirs. The impact of a minimal R and D program and the impact of expanded R and D program were estimated on the basis of its effect upon industry investment decision criteria (e.g., the cost of power). The Task Force estimates comparing three different scenarios: (1) no program, (2) minimal R and D, and (3) expanded R and D are presented.

  1. Targeting organic molecules in hydrothermal environments on Mars

    Science.gov (United States)

    Parnell, J.; Bowden, S. A.; Lindgren, P.; Wilson, R.; Cooper, J. M.

    2008-09-01

    . Discharging fluids will also precipitate minerals due to drop in temperature and pressure, and colonising organisms are likely to become entrained by the minerals. Attempts to find evidence of microbial activity related to hydrothermal systems in the geological record have therefore been focussed on hydrothermal mineral precipitates. Organic matter is found in hydrothermal precipitates back into the Precambrian [6]. Fig. 1 Settings for organic matter in hydrothermal systems. Surface discharge could be in subaerial or subaqueous environment. Application of SERS Studies using conventional laser Raman instruments have made a good case for application of this type of spectroscopy to planetary exploration. The detection of pigments sited in microbial matter in a range of samples from extreme environments (e.g. [7]) has supported development of the technique for space exploration generally, and Mars exploration in particular [8]. A major advantage of conventional Raman spectroscopy is that it can be applied to simultaneous characterization of bond types in both organic and inorganic materials. Surface-Enhanced Raman Spectroscopy (SERS) increases the sensitivity by several orders of magnitude, and overcomes the problems created by natural fluorescence [9]. SERS is achieved by adsorbing the target analyte onto the surface of a metal. We are combining the additional sample processing necessary for SERS with sample preparation in a microfluidic format (including extraction and sample concentration). The final result will be a very rapid assay, capable of detecting ppb concentrations of certain organic analytes. This approach was tested at a site in Iceland, where young/active hydrothermal systems are focussed in a rift environment. Sulphur species are prevalent, in a range of oxidation states, including sulphates, sulphides and native sulphur. Thus they are a useful model for systems that might exist on Mars, where sulphur species are widespread and therefore likely to be incorporated

  2. Hydrothermal synthesis, structure and characterization of new NASICON related potassium iron (III) pyrophosphate

    Indian Academy of Sciences (India)

    G S Gopalakrishna; B H Doreswamy; M J Mahesh; M Mahendra; M A Sridhar; J Shashidhara Prasad; K G Ashamanjari

    2005-02-01

    A new potassium iron (III) pyrophosphate was synthesized by hydrothermal technique and characterized by X-ray studies. The compound crystallizes in a monoclinic space group, 21/, with cell parameters, = 7.365(2) Å, = 10.017(2) Å, = 8.214(1) Å, = 106.50(1)° and = 4. The structure has tunnel-type cavities and are congenial for ion transportation through them. The compound exhibits moderate thermal stability.

  3. Debris flow evolution and the activation of an explosive hydrothermal system; Te Maari, Tongariro, New Zealand

    Science.gov (United States)

    Procter, J. N.; Cronin, S. J.; Zernack, A. V.; Lube, G.; Stewart, R. B.; Nemeth, K.; Keys, H.

    2014-10-01

    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 hydrothermally altered clay layer. This landslide led to a pressure drop of up to 0.5 MPa, enough to generate an explosive eruption from the hydrothermal system 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.

  4. Volcano electrical tomography unveils edifice collapse hazard linked to hydrothermal system structure and dynamics

    Science.gov (United States)

    Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique

    2016-01-01

    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 hydrothermal 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 hydrothermal system dynamics on the hazards associated to collapse-prone altered volcanic edifices. PMID:27457494

  5. Geophysical observations at natural and exploited hydrothermal systems in West Java, Indonesia

    Science.gov (United States)

    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

    2014-05-01

    We assess geothermal resources from our understanding of the structure and the dynamics of geothermal reservoirs and hydrothermal systems 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 hydrothermal 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.

  6. Hydrothermal flow regime and magmatic heat source of the Cerro Prieto geothermal system, Baja California, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Elders, W.A.; Bird, D.K.; Schiffman, P.; Williams, A.E.

    1984-01-01

    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 hydrothermal 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 hydrothermal system 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.

  7. Volcano electrical tomography unveils edifice collapse hazard linked to hydrothermal system structure and dynamics.

    Science.gov (United States)

    Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique

    2016-07-26

    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 hydrothermal 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 hydrothermal system dynamics on the hazards associated to collapse-prone altered volcanic edifices.

  8. Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics

    Science.gov (United States)

    Peacock, J. R.; Mangan, M. T.; McPhee, D.; Wannamaker, P. E.

    2016-08-01

    Though shallow flow of hydrothermal fluids in Long Valley Caldera, California, has been well studied, neither the hydrothermal source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic system 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 hydrothermal system, 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.

  9. Stochastic Dynamic Programming Applied to Hydrothermal Power Systems Operation Planning Based on the Convex Hull Algorithm

    Directory of Open Access Journals (Sweden)

    Bruno H. Dias

    2010-01-01

    Full Text Available This paper presents a new approach for the expected cost-to-go functions modeling used in the stochastic dynamic programming (SDP algorithm. The SDP technique is applied to the long-term operation planning of electrical power systems. Using state space discretization, the Convex Hull algorithm is used for constructing a series of hyperplanes that composes a convex set. These planes represent a piecewise linear approximation for the expected cost-to-go functions. The mean operational costs for using the proposed methodology were compared with those from the deterministic dual dynamic problem in a case study, considering a single inflow scenario. This sensitivity analysis shows the convergence of both methods and is used to determine the minimum discretization level. Additionally, the applicability of the proposed methodology for two hydroplants in a cascade is demonstrated. With proper adaptations, this work can be extended to a complete hydrothermal system.

  10. An oxygen isotope and geochemical study of meteoric-hydrothermal systems at Pilot Mountain and selected other localities, Carolina slate belt

    Science.gov (United States)

    Klein, T.L.; Criss, R.E.

    1988-01-01

    Several epigenetic mineral deposits in the Carolina slate belt are intimately related to meteoric-hydrothermal systems of late Precambrian and early Paleozoic age. At Pilot Mountain, low 18O rocks correlate well with zones of strong silicic alteration and alkali leaching accompanied by high alumina minerals (sericite, pyrophyllite, andalusite ?? topaz) and anomalous concentrations of Cu, Mo, Sn, B, and Au. A magmatic source for much of the sulfur and metal is likely, and a subordinate magmatic water component in the fluid of the central zone is possible. This central zone is surrounded by a >30 km2 peripheral zone of low 18O sericite schists, chlorite-sericite schists, and andesitic volcanic rocks. Reconnaissance studies of other alteration zones in the Carolina slate belt have so far disclosed the involvement of meteoric-hydrothermal fluids at the Snow Camp pyrophyllite deposit, at the Hoover Hill and Sawyer Au mines, and probably at the Haile and Brewer Au mines. -from Authors

  11. Normal Faulting, Fluid Upflow Pathways, and Alteration in the Subsurface of a Seafloor Ultramafic-Hosted Hydrothermal System, northern Apennines, Italy

    Science.gov (United States)

    Alt, J.; Levine, D.; Crispini, L.; Gaggero, L.; Shanks, W. C., III; Gulbransen, C.

    2016-12-01

    We document the mineralogy and geochemistry of a fault that acted as a hydrothermal upflow zone in the subsurface of a seafloor ultramafic-hosted hydrothermal system in the northern Apennines, Italy. The objectives are to understand fluid flow pathways, and the relative roles of upwelling hydrothermal fluids versus cold seawater and biological effects in such systems on the modern seafloor, which is much more difficult to access and study. Peridotites were exposed on the seafloor by detachment faulting, intruded by MORB gabbros, and are overlain by MORB lavas and pelagic sediments. North of the village of Reppia are two 1-2 m wide fault shear zones in serpentinite, oriented at a high angle to the detachment surface and extending hundreds of meters below the detachment. The host peridotite is 90-100% serpentinized, and serpentinite is highly replaced by talc plus tremolite and sulfide in the shear zones. At the paleo-seafloor, the fault offsets carbonate-cemented serpentinite breccia, talc-altered serpentinite, and serpentinite in the footwall to the west, from pillow basalts of the hanging wall on the east. Here the fault rocks consist of 90% Fe-dolomite with a few percent each of calcite, quartz, serpentine, talc, sulfides, chlorite, and trace relict Cr-spinel. The fault ends upward in massive sulfide overlain by pillow basalts and pelagic sediment. Three main alteration stages are identified. 1. Background serpentinites exhibit slight LREE enrichments and elevated d34S values (+3.9 to +5.2‰) consistent with serpentinization by upwelling hot hydrothermal fluids. 2. Talc alteration of serpentinite leads to strong LREE enrichments, negative Eu anomalies, silica metasomatism, and elevated Cu during the main hydrothermal upflow stage. 3. Carbonate alteration varies from slight veining of serpentinite to near-total replacement in the shallow fault rocks, with variable enrichments of LREE, Ca, Si, and metals. Carbonate oxygen isotope temperatures of 15-150°C and d13C

  12. Field Trip Guide to Serpentinite, Silica-Carbonate Alteration, and Related Hydrothermal Activity in the Clear Lake Region, California

    Energy Technology Data Exchange (ETDEWEB)

    Fraser Goff; George Guthrie

    1999-06-01

    This guide is designed to familiarize scientists with the geology, structure, alteration, and fluids typical of California serpentinites for purposes of carbon dioxide sequestration (Lackner et al., 1995). Goff et al. (1997) and Goff and Lackner (1998) describe the geology and geochemistry of some of the serpentinites from this area. Mechanisms of silica-carbonate alteration were outlined by Barnes et al. (1973). Donnelly-Nolan et al. (1993) most recently reviewed relations between regional hydrothermal alteration and Quarternary volcanic activity. Stanley et al. (1998) summarized geophysical characteristics of the region.

  13. Multiple objective optimization of hydro-thermal systems using Ritz's method

    Directory of Open Access Journals (Sweden)

    Arnáu L. Bayón

    1999-01-01

    Full Text Available This paper examines the applicability of the Ritz method to multi-objective optimization of hydro-thermal systems. The algorithm proposed is aimed to minimize an objective functional that incorporates the cost of energy losses, the conventional fuel cost and the production of atmospheric emissions such as NO x and SO 2 caused by the operation of fossil-fueled thermal generation. The formulation includes a general layout of hydro-plants that may form multi-chains of reservoir network. Time-delays are included and the electric network is considered by using the active power balance equation. The volume of water discharge for each hydro-plant is a given constant amount from the optimization interval. The generic minimization algorithm, which is not difficult to construct on the basis of the Ritz method, has certain advantages in comparison with the conventional methods.

  14. PRESENT STATE OF THE HYDROTHERMAL SYSTEM IN LONG VALLEY CALDERA, CALIFORNIA.

    Science.gov (United States)

    Sorey, Michael L.

    1985-01-01

    Results of test drilling to depths of 2 km and data on the chemical and isotopic content of waters from hot springs and fumaroles permit a conceptual model of the present-day hydrothermal system in Long Valley caldera to be delineated. The model consists of two principal zones in which hot water flows laterally from west to east at depths less than 1 km within and around the resurgent dome. Maximum measured temperatures within these zones are near 170 degree C, but estimates from chemical geothermometers and extrapolation of a high temperature gradient measured in a recent drill hole indicate that a source reservoir at temperatures near 240 degree C may exist at greater depths in the Bishop Tuff beneath the west moat.

  15. Multi-parametric investigation of the volcano-hydrothermal system at Tatun Volcano Group, Northern Taiwan

    Directory of Open Access Journals (Sweden)

    S. Rontogianni

    2012-07-01

    Full Text Available 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-hydrothermal system 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 hydrothermal system. 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.

  16. The structure of a hydrothermal system from an integrated geochemical, geophysical, and geological approach: The Ischia Island case study

    Science.gov (United States)

    di Napoli, R.; Martorana, R.; Orsi, G.; Aiuppa, A.; Camarda, M.; de Gregorio, S.; Gagliano Candela, E.; Luzio, D.; Messina, N.; Pecoraino, G.; Bitetto, M.; de Vita, S.; Valenza, M.

    2011-07-01

    The complexity of volcano-hosted hydrothermal systems is such that thorough characterization requires extensive and interdisciplinary work. We use here an integrated multidisciplinary approach, combining geological investigations with hydrogeochemical and soil degassing prospecting, and resistivity surveys, to provide a comprehensive characterization of the shallow structure of the southwestern Ischia's hydrothermal system. We show that the investigated area is characterized by a structural setting that, although very complex, can be schematized in three sectors, namely, the extra caldera sector (ECS), caldera floor sector (CFS), and resurgent caldera sector (RCS). This contrasted structural setting governs fluid circulation. Geochemical prospecting shows, in fact, that the caldera floor sector, a structural and topographic low, is the area where CO2-rich (>40 cm3/l) hydrothermally mature (log Mg/Na ratios 150 g m-2 d-1), is clearly captured by electrical resistivity tomography (ERT) and transient electromagnetic (TEM) surveys as a highly conductive (resistivity 10,000 mg/l) and poorly conductive meteoric-derived (TDS Ischia's hydrothermal system.

  17. Chemical variation in hydrothermal minerals of the Los Humeros geothermal system, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Serrano, R.G. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico). Insituto de Geofisica

    2002-10-01

    The Los Humeros geothermal system is composed of more than 2200 m of Quaternary altered volcanic rocks and an underlying Cretaceous sedimentary sequence. The low salinity of the fluids discharged at present (Na{sup +} and Cl{sup -} concentrations <500 ppm), and the excess steam, indicate that the reservoir contains a mixture of steam and dilute groundwater. Water-rock equilibrium is not attained. Hydrothermal minerals are present in veinlets, vugs, and replacing primary minerals. Three mineral zones are recognized: 1) a shallow argillic zone (<400 m depth), 2) a propylitic zone (ranging between 500 and 1800 m) and 3) a skarn zone (>1800 m). Petrographic examination of cuttings from five wells and temperature data indicate at least two stages of hydrothermal activity. Temperature is the main factor that affects the chemical composition of chlorite, epidote and biotite. Fe{sup 2+} and Al{sup IV} increase in chlorite with temperature [from 1.4 formula position unit (fpu) to 2.8, and from 0.7 to 2.4 fpu, respectively]. The pistacite content of epidote varies from 18 to 33 mol% in high-temperature regions (>270 {sup o}C) and from 13 to 26 mol% in low-temperature regions (<250 {sup 0}C). Biotite displays a slight increase in Al{sup IV} contents (1.55-2.8) and octahedral occupancy (5.93-6.0 fpu) with temperature. Whole rock composition and variations in oxygen fugacity condition are factors that also affect the concentrations of Fe, Al and Mg in the octahedral sites of chlorite, epidote, biotite and amphiboles. Chemical variations observed in alteration minerals at different depths in the Colapso Central-Xalapazco region could be used as indicator of relict physico-chemical conditions in the reservoir, before the present economic exploitation. (author)

  18. Geology and mineralogy of the Auki Crater, Tyrrhena Terra, Mars: A possible post impact-induced hydrothermal system

    Science.gov (United States)

    Carrozzo, F. G.; Di Achille, G.; Salese, F.; Altieri, F.; Bellucci, G.

    2017-01-01

    A variety of hydrothermal environments have been documented in terrestrial impact structures. Due to both past water interactions and meteoritic bombardment on the surface of Mars, several authors have predicted various scenarios that include the formation of hydrothermal systems. Geological and mineralogical evidence of past hydrothermal activity have only recently been found on Mars. Here, we present a geological and mineralogical study of the Auki Crater using the spectral and visible imagery data acquired by the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars), CTX (Context Camera) and HiRISE (High Resolution Imaging Science Experiment) instruments on board the NASA MRO mission. The Auki Crater is a complex crater that is ∼38 km in diameter located in Tyrrhena Terra (96.8°E and 15.7°S) and shows a correlation between its mineralogy and morphology. The presence of minerals, such as smectite, silica, zeolite, serpentine, carbonate and chlorite, associated with morphological structures, such as mounds, polygonal terrains, fractures and veins, suggests that the Auki Crater may have hosted a post impact-induced hydrothermal system. Although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate-rich bedrock units as a consequence of crater formation, we favor the hypothesis of impact-induced hydrothermal circulation within fractures and subsequent mineral deposition. The hydrothermal system could have been active for a relatively long period of time after the impact, thus producing a potential transient habitable environment. It must be a spectrally neutral component to emphasize the spectral features; It is an average of spectra taken in the same column of the numerator spectra to correct the residual instrument artifacts and reduce detector noise that changes from column to column; It must be taken in

  19. Exopolysaccharides isolated from hydrothermal vent bacteria can modulate the complement system.

    Science.gov (United States)

    Courtois, Anthony; Berthou, Christian; Guézennec, Jean; Boisset, Claire; Bordron, Anne

    2014-01-01

    The complement system is involved in the defence against bacterial infection, or in the elimination of tumour cells. However, disturbances in this system contributes to the pathogenesis of various inflammatory diseases. The efficiency of therapeutic anti-tumour antibodies is enhanced when the complement system is stimulated. In contrast, cancer cells are able to inhibit the complement system 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 hydrothermal 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 system by either native or over-sulphated low molecular weight EPSs isolated from vent bacteria in order to find pro or anti-activators of complement.

  20. Origin and time-space distribution of hydrothermal systems in east-central Australian sedimentary basins: Constraints from illite geochronology and isotope geochemistry.

    Science.gov (United States)

    Uysal, I. Tonguç

    2016-04-01

    Some well-known precious mineral deposits and hydrocarbon resources occur extensively in east-central Australian sedimentary Basins. The metal occurrences are abundant in northwestern and eastern part of Queensland, whereas no significant deposits are known in large areas further south, which may, however, be hidden beneath the Jurassic-Cretaceous sedimentary basins. Important hydrocarbon resources exist within the Jurassic-Cretaceous sedimentary rocks at relatively shallow depths, of which the distribution represent zones of high paleo-geothermal gradients. This study examines the time-space distribution in relation to the regional tectonic history of concealed metal deposits and areas of high paleo-geothermal gradient leading to hydrocarbon maturation. To this end, authigenic illitic clay minerals representing various locations and stratigraphic depths in east-central Australia were investigated, of which the Rb-Sr and Ar-Ar geochronology and stable isotope geochemistry assist in delineating zones of hydrothermal systems responsible for hydro-carbon maturation/migration and potentially ore deposition. The Late Carboniferous - Early Permian crustal extension that affected large areas of eastern Australia and led to the epithermal mineralisations (e.g., the Drummond Basin) is also recorded in northern South Australia and southwest Queensland. A Late Triassic - Early Jurassic tectonic event being responsible for coal maturation and gas generation in the Bowen Basin and the epithermal mineralisation in the North Arm goldfield in SE Queensland likewise affected the areas much further west in Queensland. Some illites from the basement in outback Queensland and fault gouges from the Demon Fault in NE New South Wales yield younger Rb-Sr and Ar-Ar ages indicating the effect of hydrothermal processes as a result of a Middle-Upper Jurassic tectonic event. The majority of illite samples from the crystalline basement rocks, Permian Cooper Basin, and Jurassic

  1. 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

    Science.gov (United States)

    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

  2. Halogens behaviours in Magma Degassing: Insights into Eruptive Dynamics, Hydrothermal Systems and Atmospheric Impact of Andesitic Volcanism

    Science.gov (United States)

    Villemant, B.; Balcone, H.; Mouatt, J.; Michel, A.; Komorowski, J.; Boudon, G.

    2007-12-01

    Shallow degassing of H2O in andesitic magmas determines the eruptive styles of volcanic eruptions and contributes to the hydrothermal systems developed around active volcanoes. Halogens behaviour during magma degassing primarily depends on their incompatible behaviour in the melts and on water solubility. Thus, residual contents of halogens in volcanic juvenile vitric clasts may be used as tracers of H2O degassing processes during explosive and effusive eruptions. Because of the large range of water-melt partition coefficients of halogens and their relatively low diffusion coefficients, a comparison of F, Cl, Br and I contents in volcanic clasts in function of their vesicularity and micro-cristallinity allows to precisely model the main degassing processes and to establish constraints on pre-eruptive conditions. Halogens acids (HCl, HBr and HI) extracted in the vapour phase have much more complex behaviours because of their high solubility in low temperature thermal waters, their variable condensation temperatures and their very high reactivity when mixed with low temperature and oxidizing atmospheric gases. A comparison of model compositions of high temperature gases with the composition of thermal waters, and gases from fumaroles or plumes of active volcanoes allows to characterise the shallow volcanic system and its evolutionary states. Variable halogen behaviours are discussed for a variety of eruption types (plinian, vulcanian and dome-forming) and active volcanic systems from the Lesser Antilles (Montagne Pelee, Soufrière of Guadeloupe, Soufriere Hills of Montserrat).

  3. A seismic network to investigate the sedimentary hosted hydrothermal Lusi system

    Science.gov (United States)

    Javad Fallahi, Mohammad; Mazzini, Adriano; Lupi, Matteo; Obermann, Anne; Karyono, Karyono

    2016-04-01

    The 29th of May 2006 marked the beginning of the sedimentary hosted hydrothermal Lusi system. During the last 10 years we witnessed numerous alterations of the Lusi system 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 system 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.

  4. Development of an in situ fiber optic Raman system to monitor hydrothermal vents.

    Science.gov (United States)

    Battaglia, Tina M; Dunn, Eileen E; Lilley, Marvin D; Holloway, John; Dable, Brian K; Marquardt, Brian J; Booksh, Karl S

    2004-07-01

    The development of a field portable fiber optic Raman system modified from commercially available components that can operate remotely on battery power and withstand the corrosive environment of the hydrothermal vents is discussed. The Raman system 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 system 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)(-).

  5. Neuro-Fuzzy Computational Technique to Control Load Frequency in Hydro-Thermal Interconnected Power System

    Science.gov (United States)

    Prakash, S.; Sinha, S. K.

    2015-09-01

    In this research work, two areas hydro-thermal power system 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 system parameters at nominal value. The main purpose of system generation control is to balance the system generation against the load and losses so that the desired frequency and power interchange between neighboring systems 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 systems. 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 system 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 system. 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.

  6. Sulfur isotopic composition of modern seafloor hydrothermal sediment and its geological significance

    Institute of Scientific and Technical Information of China (English)

    曾志刚; 李军; 蒋富清; 秦蕴珊; 翟世奎

    2002-01-01

    A total of 1 264 sulfur isotopic values for modem seafloor hydrothermel sediments from different hydrothermal fidds have been collected. On this basis, combining our sulfur isotpic data for surface hydrothermal sediments from the Jade hydrohtermal field in the Okinawa Trough and the TAG hydrothermal field in the Mid-Atlantic Ridge, respectively, and comparing the sulfur isotopic compositions and analyzing their sources of sulfur in seafloor hydrothermal sediments from different geologic-tectonic setting, the results show that: ( 1 ) sulfur isotopic values of sulfides and sulfates in modern seafloor hydrothermal sediments are concentrated in a narrow range, δ34S values of sulfides vary from l × 10-3 to 9 × 10- 3, with a mean of 4.5 × 10- 3 ( n = 1 042), δ34S values of sulfates vary from 19 × 10- 3 to 24× 10-3, with a mean of 21.3× 10-3 (n =217); (2) comparing the sulfur isotopic compositions of hydrothermal sediments from the sediment-hosted hydrothermal fields, the range of sulfur isotopic values for hydrothermal sediments from the sediment-free hydrothermal fields is narrow relatively; (3) the differences of sulfur isotopic compositions in sulfides from different hydrothermal fields show the differences in the sources of sulfur. The sulfur of hydrothermal sulfides in the sediment-free mid-ocean ridges is mainly from mid-ocean ridge basalt, and partially from the reduced seawater sulfate, and it is the result of partially reduced seawater sulfate mixed with basaltic sulfur. In the sediment-hosted nid-ocean ridges and the back-arc basins, the volcanics, the sediments and the organic matters also can offer their sulfur for forming hydrothermal sulfides; (4) the variations of sulfur isotopic compositions and the different sources of sulfur for hydrothermal sediments may be attributed to the various physical-chemical characteristics of hydrothermal fluids, the magmatic evolution and the different geologic-tectonic settings of seafloor hydrothermal systems.

  7. Coupled Ge/Si and Ge isotope ratios as geochemical tracers of seafloor hydrothermal systems: Case studies at Loihi Seamount and East Pacific Rise 9°50‧N

    Science.gov (United States)

    Escoube, Raphaelle; Rouxel, Olivier J.; Edwards, Katrina; Glazer, Brian; Donard, Olivier F. X.

    2015-10-01

    Germanium (Ge) and Silicon (Si) exhibit similar geochemical behavior in marine environments but are variably enriched in seafloor hydrothermal fluids relative to seawater. In this study, Ge isotope and Ge/Si ratio systematics were investigated in low temperature hydrothermal vents from Loihi Seamount (Pacific Ocean, 18°54‧N, 155°15‧W) and results were compared to high-temperature vents from the East Pacific Rise (EPR) at 9°50‧N. Loihi offers the opportunity to understand contrasting Ge and Si behavior in low temperature seafloor hydrothermal systems characterized by abundant Fe oxyhydroxide deposition at the seafloor. The results show that both Ge/Si and δ74/70Ge in hydrothermal fluids are fractionated relative to the basaltic host rocks. The enrichment in Ge vs. Si relative to fresh basalts, together with Ge isotope fractionation (Δ74/70Gefluid-basalt up to 1.15‰ at EPR 9°50‧N and 1.64‰ at Loihi) are best explained by the precipitation of minerals (e.g. quartz and Fe-sulfides) during higher temperature seawater-rock reactions in the subsurface. The study of Fe-rich hydrothermal deposits at Loihi, largely composed of Fe-oxyhydroxides, shows that Ge isotopes are also fractionated upon mineral precipitation at the seafloor. We obtained an average Ge isotope fractionation factor between Fe-oxyhydroxide (ferrihydrite) and dissolved Ge in the fluid of -2.0 ± 0.6‰ (2sd), and a maximum value of -3.6 ± 0.6‰ (2sd), which is consistent with recent theoretical and experimental studies. The study of a hydrothermal chimney at Bio 9 vent at EPR 9°50‧N also demonstrates that Ge isotopes are fractionated by approximately -5.6 ± 0.6‰ (2sd) during precipitation of metal sulfides under hydrothermal conditions. Using combined Ge/Si and estimated Ge isotope signatures of Ge sinks and sources in seawater, we propose a preliminary oceanic budget of Ge which reveals that an important sink, referred as the "missing Ge sink", may correspond to Ge sequestration

  8. Production of fuel range oxygenates by supercritical hydrothermal liquefaction of lignocellulosic model systems

    DEFF Research Database (Denmark)

    Pedersen, Thomas Helmer; Rosendahl, Lasse Aistrup

    2015-01-01

    Lignocellulosic model compounds and aspen wood are processed at supercritical hydrothermal conditions to study and understand feedstock impact on biocrude formation and characteristics. Glucose and xylose demonstrate similar yield of biocrude and biochar, similar biocrude characteristics, and it ......Lignocellulosic model compounds and aspen wood are processed at supercritical hydrothermal conditions to study and understand feedstock impact on biocrude formation and characteristics. Glucose and xylose demonstrate similar yield of biocrude and biochar, similar biocrude characteristics...

  9. Volcanic Lake System at Aso Volcano, Japan: Fluctuations in the Supply of Volcanic Fluid from the Hydrothermal System beneath the Crater Lake (Invited)

    Science.gov (United States)

    Terada, A.; Hashimoto, T.; Kagiyama, T.

    2010-12-01

    Hot crater lakes that develop upon active volcanoes generally overlie the magma-hydrothermal system. At hot crater lakes, most of the thermal energy and mass injected into the lake bottom is trapped in the lake water. It is therefore possible to detect even slight changes in subaqueous geothermal activity. The 1st crater of Nakadake, Aso volcano, Japan, contains a hot crater lake, locally called Yudamari, which is about 200 m in diameter. During a recent calm period, water temperature is around 60-70 °C, and heat discharge from lake surface is approximately constant at 200-300 MW. Historical documents report that Yudamari has repeatedly appeared and disappeared over the past 1,500 years. Changes in water level and temperature suggest that the state of Yudamari is related to volcanic activity, as also reported for Poás in Costa Rica and for Ruapehu in New Zealand. These changes in lake water are probably caused by changes in the input of volcanic fluid to the crater bottom. Therefore, precise observations and analysis of a hot crater lake would reveal the nature of variations in the input of volcanic fluid that originated from the underlying hydrothermal system. However, direct monitoring of the lake water at Yudamari is made difficult by the steep topography and high concentrations of SO2 gas. The recent compilation of a 1-mesh digital surface model (DSM) and installation of a commercial digital camera enabled precise and continuous monitoring of water level with an average accuracy of 10-20 cm. As a result we observed characteristic patterns of change in lake level that show no direct correlation with precipitation, suggesting fluctuations in the supply of volcanic fluid to lake water. To estimate temporal variations in flux and enthalpy from the lake bottom, we developed a numerical model of a hot crater lake applied to the precise observation data for the period from July 2006 to January 2009. The analyses revealed seasonal changes in mass flux (66-132 kg

  10. Carbon geochemistry of serpentinites in the Lost City Hydrothermal System (30°N, MAR)

    Science.gov (United States)

    Delacour, Adélie; Früh-Green, Gretchen L.; Bernasconi, Stefano M.; Schaeffer, Philippe; Kelley, Deborah S.

    2008-08-01

    The carbon geochemistry of serpentinized peridotites and gabbroic rocks recovered at the Lost City Hydrothermal Field (LCHF) and drilled at IODP Hole 1309D at the central dome of the Atlantis Massif (Mid-Atlantic Ridge, 30°N) was examined to characterize carbon sources and speciation in oceanic basement rocks affected by long-lived hydrothermal alteration. Our study presents new data on the geochemistry of organic carbon in the oceanic lithosphere and provides constraints on the fate of dissolved organic carbon in seawater during serpentinization. The basement rocks of the Atlantis Massif are characterized by total carbon (TC) contents of 59 ppm to 1.6 wt% and δ 13C TC values ranging from -28.7‰ to +2.3‰. In contrast, total organic carbon (TOC) concentrations and isotopic compositions are relatively constant (δ 13C TOC: -28.9‰ to -21.5‰) and variations in δ 13C TC reflect mixing of organic carbon with carbonates of marine origin. Saturated hydrocarbons extracted from serpentinites beneath the LCHF consist of n-alkanes ranging from C 15 to C 30. Longer-chain hydrocarbons (up to C 40) are observed in olivine-rich samples from the central dome (IODP Hole 1309D). Occurrences of isoprenoids (pristane, phytane and squalane), polycyclic compounds (hopanes and steranes) and higher relative abundances of n-C 16 to n-C 20 alkanes in the serpentinites of the southern wall suggest a marine organic input. The vent fluids are characterized by high concentrations of methane and hydrogen, with a putative abiotic origin of hydrocarbons; however, evidence for an inorganic source of n-alkanes in the basement rocks remains equivocal. We propose that high seawater fluxes in the southern part of the Atlantis Massif likely favor the transport and incorporation of marine dissolved organic carbon and overprints possible abiotic geochemical signatures. The presence of pristane, phytane and squalane biomarkers in olivine-rich samples associated with local faults at the central

  11. Structural Architecture of the Hydrothermal System from Geophysical Data in Hammam Bouhadjar Area (Northwest of Algeria)

    Science.gov (United States)

    Bouyahiaoui, Boualem; Abtout, Abdeslam; Hamai, Lamine; Boukerbout, Hassina; Djellit, Hamou; Bougchiche, Said Sofiane; Bendali, Mohamed; Bouabdallah, Hamza

    2017-03-01

    We determine the structural architecture of the hydrothermal system 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 system. 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.

  12. Tectonic localization of multi-plume hydrothermal fluid flow in a segmented rift system, Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Rowland, J. V.; Downs, D. T.; Scholz, C.; de P. S. Zuquim, M.

    2013-05-01

    High-temperature (>250°C) multi-plume hydrothermal systems occur in a range of tectonic settings, though most are extensional or transtensional. A key feature of such settings is their tendency to partition into discrete structural elements that scale with the thickness of the seismogenic zone. The late Miocene to present record of arc magmatism and rifting in the North Island of New Zealand illustrates the importance of structural segmentation and reactivation of inherited basement fabrics on the localisation of hydrothermal upflow. The 15 My record of similarly-oriented magmatism, rifting and hydrothermal activity associated with subduction of the Pacific Plate beneath the North Island of New Zealand. Lateral migration of the locus of arc magmatism, concomitant with roll-back of the subducting slab, is supported by the SE-directed younging of: 1) volcanism; 2) fault-controlled rift basins; and 3) hydrothermal activity, represented by the distribution of epithermal mineralisation within the ~15-3 Ma Coromandel Volcanic Zone (CVZ), and geothermal activity within the TVZ. Currently the TVZ is extending in a NW-SE direction at a rate that varies from ~3 mm/yr to ~15 mm/yr from SW to NE, respectively. The TVZ is partitioned into discrete rift segments, comprising arrays of NE-striking normal faults of ~20 km in length, as expected on mechanical grounds for the 6-8 km-thick seismogenic zone. Transfer zones between rift segments coincide with N-to-NW-trending alignments of geothermal fields, spaced ~ 30 km apart can be recognized elsewhere within the CVZ. The most productive epithermal deposits to date are localised where these inferred transfer zones intersect arc-parallel fault arrays. A similar tectonic configuration occurs in the Deseado Massif, Argentinian Patagonia, where interplay between transfer and rift faults is inferred to have localized hydrothermal fluids in small pull-apart basins and arrays of extension veins for durations >30 My.

  13. Biogenic Iron-Rich Filaments in the Quartz Veins in the Uppermost Ediacaran Qigebulake Formation, Aksu Area, Northwestern Tarim Basin, China: Implications for Iron Oxidizers in Subseafloor Hydrothermal Systems.

    Science.gov (United States)

    Zhou, Xiqiang; Chen, Daizhao; Tang, Dongjie; Dong, Shaofeng; Guo, Chuan; Guo, Zenghui; Zhang, Yanqiu

    2015-07-01

    Fe-(oxyhydr)oxide-encrusted filamentous microstructures produced by microorganisms have been widely reported in various modern and ancient extreme environments; however, the iron-dependent microorganisms preserved in hydrothermal quartz veins have not been explored in detail because of limited materials available. In this study, abundant well-preserved filamentous microstructures were observed in the hydrothermal quartz veins of the uppermost dolostones of the terminal-Ediacaran Qigebulake Formation in the Aksu area, northwestern Tarim Basin, China. These filamentous microstructures were permineralized by goethite and hematite as revealed by Raman spectroscopy and completely entombed in chalcedony and quartz cements. Microscopically, they are characterized by biogenic filamentous morphologies (commonly 20-200 μm in length and 1-5 μm in diameter) and structures (curved, tubular sheath-like, segmented, and mat-like filaments), similar to the Fe-oxidizing bacteria (FeOB) living in modern and ancient hydrothermal vent fields. A previous study revealed that quartz-barite vein swarms were subseafloor channels of low-temperature, silica-rich, diffusive hydrothermal vents in the earliest Cambrian, which contributed silica to the deposition of the overlying bedded chert of the Yurtus Formation. In this context, this study suggests that the putative filamentous FeOB preserved in the quartz veins might have thrived in the low-temperature, silica- and Fe(II)-rich hydrothermal vent channels in subseafloor mixing zones and were rapidly fossilized by subsequent higher-temperature, silica-rich hydrothermal fluids in response to waning and waxing fluctuations of diffuse hydrothermal venting. In view of the occurrence in a relatively stable passive continental margin shelf environment in Tarim Block, the silica-rich submarine hydrothermal vent system may represent a new and important geological niche favorable for FeOB colonization, which is different from their traditional

  14. Electromagnetic outline of the Solfatara-Pisciarelli hydrothermal system, Campi Flegrei (Southern Italy)

    Science.gov (United States)

    Troiano, A.; Di Giuseppe, M. G.; Patella, D.; Troise, C.; De Natale, G.

    2014-05-01

    We describe the results from a combined controlled source audio magnetotelluric (CSAMT) and natural source magnetotelluric (MT) survey carried out in the Solfatara-Pisciarelli (S-P) area, located in the central part of the Campi Flegrei (CF) composite caldera, west of Naples, Southern Italy. The S-P area represents the most active zone within the CF caldera, in terms of hydrothermal manifestations and local seismicity. Since 1969, the CF caldera is experiencing ground deformation, seismicity and geochemical fluid changes, which are particularly evident in the S-P area. A 1 km long, nearly W-E directed CSAMT-MT profile crossing the fumarole field was carried out in the S-P area with the aim of deducting a resistivity model of the structural setting of the hydrothermal system in the first 3 km depth. An interpretation of the modelled section across the profile is given in this paper, taking advantage from already existing seismic, gravity and geochemical data in the same area. Three well distinct zones have been outlined. The first zone is a very shallow, electrically conductive body localized beneath the westernmost segment of the profile, which, within a short distance of about 100 m, dips westwards from near surface down to some hundred metres in depth. Mostly accounting for the very low resistivity (1-10 Ω m) and the exceedingly high values of vP/vS (> 4), this shallow zone has been ascribed to a water-saturated, high-pressurized geothermal reservoir. The second zone, which has been localized below the west-central portion of the CSAMT-MT transect, appears as a composite body made up of a nearly vertical plumelike structure that escapes at about 2.25 km depth from the top edge of the east side of a presumably horizontal platelike body. The plumelike structure rises up to the free surface in correspondence of the fumarole field, whereas the platelike structure deepens at least down to the 3 km of maximum exploration depth. The combined interpretation of

  15. In situ Expression of Functional Genes Reveals Nitrogen Cycling at High Temperatures in Terrestrial Hydrothermal Systems

    Science.gov (United States)

    Loiacono, S. T.; Meyer-Dombard, D. R.

    2011-12-01

    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 hydrothermal systems. 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.

  16. Energetics of potential heterotrophic metabolisms in the marine hydrothermal system of Vulcano Island, Italy

    Science.gov (United States)

    Rogers, Karyn L.; Amend, Jan P.

    2006-12-01

    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 hydrothermal system 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 hydrothermal conditions and represent a plethora of potential metabolisms for Vulcano's diverse thermophilic heterotrophs.

  17. The submarine hydrothermal system of Panarea (Southern Italy: biogeochemical processes at the thermal fluids - sea bottom interface

    Directory of Open Access Journals (Sweden)

    T. Maugeri

    2006-06-01

    Full Text Available Among the submarine hydrothermal systems located offshore the volcanic archipelago of the Aeolian Islands (Southern Italy, the most active is located off the coasts of Panarea island. Thermal waters, gases and sulfur deposits coexist at the sea bottom where hydrothermal fluids are released from both shallow and deep vents. The chemical and isotopic composition of the fluid phase shows the presence of a significant magmatic component and the physico-chemical conditions of the geothermal reservoir allow the release of reduced chemical species that are microbially mediated towards the production of organic carbon as a form of biochemical energy. Microorganisms inhabiting this environment possess nutritional requirements and overall metabolic pathways ideally suited to such ecosystem that represents a clear example of the close connection between geosphere and biosphere. Microscopic examination of the white mat attached to rock surfaces showed the presence of Thiothrix-like filamentous bacteria. Moderately thermophilic heterotrophic isolates were identified as strains of the genus Bacillus. Although the hydrothermal system of Panarea has to be considered a “shallow” system, it shows many characteristics that make it similar to the “deep” oceanic systems, giving a unique opportunity for improving our knowledge on such an unexplored world by working at this easily accessible site.

  18. Physical factors determining the fraction of stored energy recoverable from hydrothermal convection systems and conduction-dominated areas

    Science.gov (United States)

    Nathenson, Manuel

    1975-01-01

    This report contains background analyses for the estimates of Nathenson and Muffler (1975) of geothermal resources in hydrothermal convection systems 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 hydrothermal convection systems 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

  19. Biogeography and evolution of Thermococcus isolates from hydrothermal vent systems of the Pacific

    Directory of Open Access Journals (Sweden)

    Mark Thomas Price

    2015-09-01

    Full Text Available Thermococcus is a genus of hyperthermophilic archaea that is ubiquitous in marine hydrothermal environments growing in anaerobic subsurface habitats but able to survive in cold oxygenated seawater. DNA analyses of Thermococcus isolates were applied to determine the relationship between geographic distribution and relatedness focusing primarily on isolates from the Juan de Fuca Ridge and South East Pacific Rise. Amplified fragment length polymorphism (AFLP analysis and multilocus sequence typing (MLST were used to resolve genomic differences in 90 isolates of Thermococcus, making biogeographic patterns and evolutionary relationships apparent. Isolates were differentiated into regionally endemic populations however there was also evidence in some lineages of cosmopolitan distribution. The biodiversity identified in Thermococcus isolates and presence of distinct lineages within the same vent site suggests the utilization of varying ecological niches in this genus. In addition to resolving biogeographic patterns in Thermococcus, this study has raised new questions about the closely related Pyrococcus genus. The phylogenetic placement of Pyrococcus type strains shows the close relationship between Thermococcus and Pyrococcus and the unresolved divergence of these two genera.

  20. Isolation and Structural Characterization of Lignin from Cotton Stalk Treated in an Ammonia Hydrothermal System

    Science.gov (United States)

    Kang, Sumin; Xiao, Lingping; Meng, Lingyan; Zhang, Xueming; Sun, Runcang

    2012-01-01

    To investigate the potential for the utilization of cotton stalk, ammonia hydrothermal treatment was applied to fractionate the samples into aqueous ammonia-soluble and ammonia-insoluble portions. The ammonia-soluble portion was purified to yield lignin fractions. The lignin fractions obtained were characterized by wet chemistry (carbohydrate analysis) and spectroscopy methods (FT-IR, 13C and 1H-13C HSQC NMR spectroscopy) as well as gel permeation chromatography (GPC). The results showed that the cotton stalk lignin fractions were almost absent of neutral sugars (0.43%–1.29%) and had relatively low average molecular weights (1255–1746 g/mol). The lignin fractions belonged to typical G-S lignin, which was composed predominately of G-type units (59%) and noticeable amounts of S-type units (40%) together with a small amount of H-type units (~1%). Furthermore, the ammonia-extractable lignin fractions were mainly composed of β-O-4′ inter-unit linkages (75.6%), and small quantities of β-β′ (12.2%), together with lower amounts of β-5′ carbon-carbon linkages (7.4%) and p-hydroxycinnamyl alcohol end groups. PMID:23203120

  1. Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of an active caldera

    OpenAIRE

    Coco, A.; Gottsmann, J.; F. Whitaker; Rust, A; G. Currenti; A. Jasim; S. Bunney

    2015-01-01

    Ground deformation and gravity changes in active 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 hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a nu...

  2. Pervasive, high temperature hydrothermal alteration in the RN-17B drill core, Reykjanes Geothermal System-Iceland Deep Drilling Project

    Science.gov (United States)

    Zierenberg, R. A.; Schiffman, P.; Marks, N. E.; Reed, M. H.; Elders, W. A.; Fridleifsson, G. O.

    2010-12-01

    burial at T<300 is replaced by more calcic plagioclase at higher temperature. Texturally, hydrothermal anorthite (An90-98) and pargasite (up to 13.5 wt % Al2O3) appear to have grown at the expense of earlier formed epidote + chlorite + actinolite. Measured downhole temperature at 2800m in RN-17B following reequilibration was 320°C, although amphibole-plagioclase geothermometry imply that anorthite + pargasite, if in equilibrium, should have formed at much higher temperatures. The differences in extent and intensity of alteration inferred from examination of cuttings compared to drill core indicate that selective recovery and mixing of cuttings from multiple depths may be a larger problem than presently appreciated. Previous work has shown that the Reykjanes geothermal system has evolved from a meteoric water-dominated system to higher salinity system dominated by seawater-recharge. The paragenetic relationships that are discernible in the core hopefully will allow us to quantify the alteration processes related to the change in salinity.

  3. An Evaluation of the Critical Parameters for Abiotic Peptide Synthesis in Submarine Hydrothermal Systems

    Science.gov (United States)

    Cleaves, H. J.; Aubrey, A. D.; Bada, J. L.

    2009-04-01

    It has been proposed that oligopeptides may be formed in submarine hydrothermal systems (SHSs). Oligopeptides have been synthesized previously under simulated SHS conditions which are likely geochemically implausible. We have herein investigated the oligomerization of glycine under SHS-like conditions with respect to the limitations imposed by starting amino acid concentration, heating time, and temperature. When 10-1 M glycine solutions were heated at 250°C for diketopiperazine (DKP) were detectable. At 200°C, less oligomerization was noted. Peptides beyond glycylglycine (gly2) and DKP were not detected below 150°C. At 10-2 M initial glycine concentration and below, only gly2, DKP, and gly3 were detected, and then only above 200°C at < 20 min reaction time. Gly3 was undetectable at longer reaction times. The major parameters limiting peptide synthesis in SHSs appear to be concentration, time, and temperature. Given the expected low concentrations of amino acids, the long residence times and range of temperatures in SHSs, it is unlikely that SHS environments were robust sources of even simple peptides. Possible unexplored solutions to the problems presented here are also discussed.

  4. Igneous Hydrothermal Alteration and Ore-Forming Processes in the Land's End Granite, Nanjizal

    OpenAIRE

    Eik, Marte

    2015-01-01

    This study addresses the hydrothermal alteration and mineralization related to a system of tourmaline-quartz veins intersecting biotite-granite in Nanjizal, in the Land s End granites of the cornubian batholith. Nanjizal is an important site as it is one of the few locations in the southern segment of the Land s End Granite where magmatic-hydrothermal tin mineralizations have been mined. The aim is to identify the alteration-patterns and their correlation with hydrothermal ore-forming events ...

  5. The Origin of Carbon-Bearing Volatiles in a Continental Hydrothermal System in the Great Basin: Water Chemistry and Isotope Characterizations

    Science.gov (United States)

    Fu, Qi; Socki, Richard A.; Niles, Paul B.; Romanek, Christopher; Datta, Saugata; Darnell, Mike

    2012-01-01

    Hydrothermal systems 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 hydrothermal alteration processes, but they also form an important component of biological systems. Studying carbon-bearing fluids from hydrothermal systems is of specific importance to understanding (bio-)geochemical processes within these systems. With recent detection of methane in the martian atmosphere [4-7] and the possibility of its hydrothermal origin [8, 9], understanding the formation mechanisms of methane may provide constraints on the history of the martian aqueous environments and climate.

  6. Induced Seismicity Related to Hydrothermal Operation of Geothermal Projects in Southern Germany - Observations and Future Directions

    Science.gov (United States)

    Megies, T.; Kraft, T.; Wassermann, J. M.

    2015-12-01

    Geothermal power plants in Southern Germany are operated hydrothermally and at low injection pressures in a seismically inactive region considered very low seismic hazard. For that reason, permit authorities initially enforced no monitoring requirements on the operating companies. After a series of events perceived by local residents, a scientific monitoring survey was conducted over several years, revealing several hundred induced earthquakes at one project site.We summarize results from monitoring at this site, including absolute locations in a local 3D velocity model, relocations using double-difference and master-event methods and focal mechanism determinations that show a clear association with fault structures in the reservoir which extend down into the underlying crystalline basement. To better constrain the shear wave velocity models that have a strong influence on hypocentral depth estimates, several different approaches to estimate layered vp/vs models are employed.Results from these studies have prompted permit authorities to start imposing minimal monitoring requirements. Since in some cases these geothermal projects are only separated by a few kilometers, we investigate the capabilities of an optimized network combining the monitoring resources of six neighboring well doublets in a joint network. Optimization is taking into account the -- on this local scale, urban environment -- highly heterogeneous background noise conditions and the feasibility of potential monitoring sites, removing non-viable sites before the optimization procedure. First results from the actual network realization show good detection capabilities for small microearthquakes despite the minimum instrumentational effort, demonstrating the benefits of good coordination of monitoring efforts.

  7. Isotopic Evidence of a Sedimentary Carbon Source at the Endeavour Hydrothermal System, a Potential Site of Microbial Methane Oxidation

    Science.gov (United States)

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

    2002-12-01

    The hydrothermal systems on the Endeavour Segment of the Juan de Fuca Ridge have long been characterized as "bare rock hosted", as there is no sediment cover at Endeavour. However, chemical evidence in the form of anomalously high methane, ammonia and various trace metal concentrations reported in the last 10 years are consistent with a sediment source at Endeavour. Here we present a unique data set of stable and radiocarbon isotopic measurements made on CO2 from Endeavour hydrothermal vent fluids. When plotted against each other, a linear relationship between δ13CO2 and CO2 fraction modern values, suggests mixing of two CO2 sources. The data supports a mixing model between a -5.4\\permil, radiocarbon dead magmatic endmember, and a -17.8\\permil, 18,500 year old carbon source. The second endmember corresponds extremely well with stable isotopic measurements made on carbonate nodules from sediments at ODP drill sites on Middle Valley, a sedimented hydrothermal site 40km North of the Endeavour Segment. These sediments were emplaced during turbidite flows in the late Pleistocene, nominally 20,000 years ago. The mixing model suggests that about 20% of the CO2 found in Endeavour hydrothermal vent fluids is from this sedimentary endmember. We propose that the observed sedimentary signal is incorporated as heated hydrothermal fluids migrate upwards beneath the ridge axis through a zone of buried sediments. An alternative explanation is that there is a hydrologic link between Middle Valley and Endeavour, and that the sedimentary signal is imported from observed sediments at Middle Valley. Sediments provide labile sources of carbon that may be incorporated into microbial metabolic pathways. Sediments at Middle Valley exhibit strongly depleted δ13CO2 values (between -27 and -44\\permil) suggesting microbial fractionation, most likely anaerobic methane oxidation. While microbial methane oxidation is likely an active process in sediments at Middle Valley, isotopic evidence

  8. The stabilisation and transportation of dissolved iron from high temperature hydrothermal vent systems

    Science.gov (United States)

    Hawkes, J. A.; Connelly, D. P.; Gledhill, M.; Achterberg, E. P.

    2013-08-01

    Iron (Fe) binding phases in two hydrothermal plumes in the Southern Ocean were studied using a novel voltammetric technique. This approach, reverse titration-competitive ligand exchange-adsorptive cathodic stripping voltammetry, showed that on average 30±21% of dissolved Fe in the hydrothermal plumes was stabilised by chemically labile binding to ligands. The conditional stability constant (log K‧FeL) of the observed complexes was 20.61±0.54 (mean±1 SD) for the two vent sites, intermediate between previous measurements of deep ocean ligands (21.4-23; Kondo et al., 2012) and dissolved weak estuarine ligands (<20; Gerringa et al., 2007). Our results indicate that approximately 7.5% of all hydrothermal Fe was stabilised by complexation with ligands. Furthermore, 47±26% of the dissolved Fe in the plume existed in the colloidal size range (0.02-0.2 μm). Our data suggests that a portion (∼7.5%) of hydrothermal Fe is sufficiently stabilised in the dissolved size fraction (<0.2 μm) to make an important impact on deep ocean Fe distributions. Lateral deep ocean currents transport this hydrothermal Fe as lenses of enhanced Fe concentrations away from mid ocean ridge spreading centres and back arc basins.

  9. Magnetic effects of hydrothermal alteration in porphyry copper and iron-oxide copper-gold systems: A review

    Science.gov (United States)

    Clark, David A.

    2014-06-01

    Magnetic anomaly patterns can be used as a tool for mapping lithology, metamorphic zones and hydrothermal alteration systems, as well as identifying structures that may control passage of magmas or hydrothermal fluids associated with mineralisation. Reliable geological interpretation of mineralised systems requires an understanding of the magmatic, metamorphic and hydrothermal processes that create, alter and destroy magnetic minerals in rocks. Predictive magnetic exploration models for porphyry copper and iron oxide copper-gold (IOCG) deposits can be derived from standard geological models by integrating magnetic petrological principles with petrophysical data, deposit descriptions, and modelling of observed magnetic signatures of these deposits. Even within a particular geological province, the magnetic signatures of similar deposits may differ substantially, due to differences in the local geological setting. Searching for “look-alike” signatures of a known deposit is likely to be unrewarding unless pertinent geological factors are taken into account. These factors include the tectonic setting and magma type, composition and disposition of host rocks, depth of emplacement and post-emplacement erosion level, depth of burial beneath younger cover, post-emplacement faulting and tilting, remanence effects contingent on ages of intrusion and alteration, and metamorphism. Because the effects of these factors on magnetic signatures are reasonably well understood, theoretical magnetic signatures appropriate for the local geological environment can qualitatively guide exploration and make semiquantitative predictions of anomaly amplitudes and patterns. The predictive models also allow detectability of deposit signatures to be assessed, for example when deposits are buried beneath a considerable thickness of nonmagnetic overburden, are covered by highly magnetic heterogeneous volcanic rocks, or there is a strong regional magnetic gradient. This paper reviews the

  10. Subseafloor fluid mixing and fossilized microbial life in a Cretaceous 'Lost City'-type hydrothermal system at the Iberian Margin

    Science.gov (United States)

    Klein, F.; Humphris, S. E.; Guo, W.; Schubotz, F.; Schwarzenbach, E. M.; Orsi, W.

    2015-12-01

    Subseafloor mixing of reduced hydrothermal 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 hydrothermal system 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 hydrothermal 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 hydrothermal 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 systems 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 systems have likely existed throughout most of Earth

  11. Petrology and oxygen isotope geochemistry of a fossil seawater hydrothermal system within the Solea graben, northern Troodos ophiolite, Cyprus

    Science.gov (United States)

    Schiffman, Peter; Smith, Brian M.

    1988-05-01

    Hydrothermal 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 hydrothermal system. 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 hydrothermal system 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.

  12. Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics

    Science.gov (United States)

    Peacock, Jared R.; Mangan, Margaret T.; McPhee, Darcy K.; Wannamaker, Phil E.

    2016-01-01

    Though shallow flow of hydrothermal fluids in Long Valley Caldera, California, has been well studied, neither the hydrothermal source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic system 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 hydrothermal system, 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.

  13. Organic compounds in hydrothermal systems on the Russian Far East: relevance to the origin of life

    Science.gov (United States)

    Kompanichenko, Vladimir

    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 hydrothermal 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 hydrothermal 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 hydrothermal systems 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 hydrothermally generated oil from the Uzon Caldera, Kamchatka. Applied Geochemistry 24: 303-309. 3. Kompanichenko V.N. 2008. Three stages of

  14. Hydrothermal dolomitization of basinal deposits controlled by a synsedimentary fault system in Triassic extensional setting, Hungary

    Science.gov (United States)

    Hips, Kinga; Haas, János; Győri, Orsolya

    2016-06-01

    Dolomitization of relatively thick carbonate successions occurs via an effective fluid circulation mechanism, since the replacement process requires a large amount of Mg-rich fluid interacting with the CaCO3 precursor. In the western end of the Neotethys, fault-controlled extensional basins developed during the Late Triassic spreading stage. In the Buda Hills and Danube-East blocks, distinct parts of silica and organic matter-rich slope and basinal deposits are dolomitized. Petrographic, geochemical, and fluid inclusion data distinguished two dolomite types: (1) finely to medium crystalline and (2) medium to coarsely crystalline. They commonly co-occur and show a gradual transition. Both exhibit breccia fabric under microscope. Dolomite texture reveals that the breccia fabric is not inherited from the precursor carbonates but was formed during the dolomitization process and under the influence of repeated seismic shocks. Dolomitization within the slope and basinal succession as well as within the breccia zones of the underlying basement block is interpreted as being related to fluid originated from the detachment zone and channelled along synsedimentary normal faults. The proposed conceptual model of dolomitization suggests that pervasive dolomitization occurred not only within and near the fault zones. Permeable beds have channelled the fluid towards the basin centre where the fluid was capable of partial dolomitization. The fluid inclusion data, compared with vitrinite reflectance and maturation data of organic matter, suggest that the ascending fluid was likely hydrothermal which cooled down via mixing with marine-derived pore fluid. Thermal gradient is considered as a potential driving force for fluid flow.

  15. Fluid mixing and the deep biosphere of a fossil Lost City-type hydrothermal system at the Iberia Margin.

    Science.gov (United States)

    Klein, Frieder; Humphris, Susan E; Guo, Weifu; Schubotz, Florence; Schwarzenbach, Esther M; Orsi, William D

    2015-09-29

    Subseafloor mixing of reduced hydrothermal 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 hydrothermal system 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 hydrothermal 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 hydrothermal 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 systems 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.

  16. Radon surveys and monitoring at active volcanoes: an open window on deep hydrothermal systems and their dynamics

    Science.gov (United States)

    Cigolini, Corrado; Laiolo, Marco; Coppola, Diego

    2017-04-01

    The behavior of fluids in hydrothermal systems is critical in volcano monitoring and geothermal prospecting. Analyzing the time series of radon emissions on active volcanoes is strategic for detecting and interpreting precursory signals of changes in volcanic activity, eventually leading to eruptions. Radon is a radioactive gas generated from the decay of U bearing rocks, soils and magmas. Although radon has been regarded as a potential precursor of earthquakes, radon anomalies appear to be better suited to forecast volcanic eruptions since we know where paroxysms may occur and we can follow the evolution of volcanic activity. Radon mapping at active volcanoes is also a reliable tool to assess diffuse and concentrated degassing as well as efficiently detecting earthquake-volcano interactions. Systematic radon monitoring has been shown to be a key factor for evaluating the rise of volcanic and hydrothermal fluids. In fact, the decay properties of radon, the duration of radon anomalies together with sampling rates may be cross-checked with the chemistry of hydrothermal fluids (and their transport properties) to constrain fluids ascent rates and to infer the permeability and porosity of rocks in sectors surrounding the active conduits. We hereby further discuss the data of radon surveys and monitoring at Somma-Vesuvius, Stromboli and La Soufrière (Guadeloupe, Lesser Antilles). The integrated analysis of seismic and geochemical data, including radon emissions, may be successfully used in testing temperature distributions and variations of porosity and permeability in volcanic hydrothermal systems and can be used as a proxy to analyze geothermal reservoirs.

  17. Making Water Chemistry Data From Volcano-Hydrothermal Systems Accessible Using Open Source Tools

    Science.gov (United States)

    Venezky, D. Y.; Mariner, R. H.; Hurwitz, S.; Evans, W. C.

    2004-12-01

    Chemical and isotopic data collected over several decades by the U.S. Geological Survey from volcano-hydrothermal systems 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 System) 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/.

  18. Shallow vs. Deep Fluid Sources In Hydrothermal Systems: New Insights From VOC Composition In Fumarolic Discharges And Soil Gases Of Yellowstone National Park (USA)

    Science.gov (United States)

    Tassi, F.; Capecchiacci, F.; Montegrossi, G.; Caliro, S.; Chiodini, G.; Vaselli, O.

    2008-12-01

    The origin of non-methane volatile organic compounds (VOCs) in hydrothermal fluids is related to two distinct mechanisms regulated by different thermodynamic conditions (e.g. Des Marais et al., 1981; Mango, 2000; Capaccioni and Mangani, 2001): i) thermogenic reactions, such as catalytic reforming and/or thermal cracking, which proceed within the main reservoir at medium-to-high temperature (150-350°C) and reduced conditions; ii) biodegradation processes, occurring at relatively shallow depth, where uprising fluids have oxidizing conditions. According to these considerations, the main aim of the present investigation is to discriminate the different fluid sources feeding the hydrothermal system on the basis of the C2-C15 organic compounds in fumarolic discharges and soil gases collected at the Yellowstone National Park (USA). A total of 64 and 66 different species were identified in the gas discharges and in the soil gas samples, respectively. The composition of the organic gas fraction in the fumarolic fluids is relatively homogeneous, being dominated by C2-C6 alkanes (81 %) and showing relatively high concentrations of alkenes (13 %), aromatics (3.7 %) and cyclics (1.4 %). Differently, the relative percentages of alkanes and alkenes in the soil gas, where VOC abundances are about two orders of magnitude less abundant than those in the gas discharges, are significantly lower (64 and 6.8 %, respectively) and cyclics are absent. On the other hand, oxygenated species (17.8 %), aromatics (5.6 %) and Cl-bearing compounds (4.5 %) results to be enriched with respect to those measured in the gas vents. Such compositional differences are likely to be due to the bacterial activity in the soil that causes the production of ketones, esters, alcohols, aldehydes and organic acids from the C-H species (hydrocarbons sensu strictu). Organic acids, mainly constituted by ossalic acid and traces of tartaric, malonic citric and succinic ones, were also determined in the fumarolic

  19. Mid-long Term Optimal Dispatching Method of Hydro-thermal Power System Considering Scheduled Maintenance

    Institute of Scientific and Technical Information of China (English)

    GE Xiaolin; SHU Jun; ZHANG Lizi

    2012-01-01

    Mid-long term hydro-thermal optimal dispatching plays an important role in mid-long term electric power and energy balance, and it also can bring significant economic benefits. This topic has been discussed in many literatures and some progress has been achieved, but there are still two problems that need to be solved. First, the modeling approach needs to be improved. When a multi-scenario model is adopted in hydro-thermal optimal dispatching, the existing modeling approaches will probably suffer from the dimensionality problem. Second, the construction of the mathematical model is not comprehensive. Generally, the existing model only considers the power balance;

  20. Hydrogeological and geochemical modeling of hydrothermal fluids circulation in active ultramafic-hosted systems under CAST3M

    Science.gov (United States)

    Perez, F.; Mugler, C.; Jean-Baptiste, P.; Charlou, J. L.; Donval, J.; Vidal, O.; Marcailloux, C.; Munoz, M.

    2010-12-01

    Hydrothermal 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 systems, 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 hydrothermal 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 hydrothermal 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.

  1. Hydrothermal alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil Hydrothermal Field

    Science.gov (United States)

    Ridley, W.I.; Perfit, M.R.; Josnasson, I.R.; Smith, M.F.

    1994-01-01

    The Galapagos Fossil Hydrothermal Field is composed of altered oceanic crust and extinct hydrothermal vents within the eastern Galapagos Rift between 85??49???W and 85??55???W. The discharge zone of the hydrothermal system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the hydrothermal alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens' equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (metal sulfides beneath the seafloor is probably a result of fluid mixing and cooling. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine hydrothermal systems. ?? 1994.

  2. High abundances of viruses in a deep-sea hydrothermal vent system indicates viral mediated microbial mortality

    Science.gov (United States)

    Ortmann, Alice C.; Suttle, Curtis A.

    2005-08-01

    Little is known about the distribution and abundance of viruses at deep-sea hydrothermal vents. Based on estimates made using epifluorescence microscopy and the dye YoPro-1, much higher viral abundances were observed at active hydrothermal 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 Endeavour Ridge system 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 Endeavour 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-hydrothermal 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 hydrothermal-vent environments is significant and may reduce energy flow to higher trophic levels.

  3. Stable isotopes of helium, nitrogen and carbon in a coastal submarine hydrothermal system

    Science.gov (United States)

    Vidal, Francisco V.; Welhan, John; Vidal, Victor M. V.

    1982-03-01

    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 hydrothermal systems are effective vehicles for mantle degassing of primordial helium.

  4. Catabolic and anabolic energy for chemolithoautotrophs in deep-sea hydrothermal systems hosted in different rock types

    Science.gov (United States)

    Amend, Jan P.; McCollom, Thomas M.; Hentscher, Michael; Bach, Wolfgang

    2011-10-01

    Active deep-sea hydrothermal vents are hosted by a range of different rock types, including basalt, peridotite, and felsic rocks. The associated hydrothermal fluids exhibit substantial chemical variability, which is largely attributable to compositional differences among the underlying host rocks. Numerical models were used to evaluate the energetics of seven inorganic redox reactions (potential catabolisms of chemolithoautotrophs) and numerous biomolecule synthesis reactions (anabolism) in a representative sampling of these systems, where chemical gradients are established by mixing hydrothermal fluid with seawater. The wide ranging fluid compositions dictate demonstrable differences in Gibbs energies (Δ G r) of these catabolic and anabolic reactions in three peridotite-hosted, six basalt-hosted, one troctolite-basalt hybrid, and two felsic rock-hosted systems. In peridotite-hosted systems at low to moderate temperatures (10), hydrogen oxidation yields the most catabolic energy, but the oxidation of methane, ferrous iron, and sulfide can also be moderately exergonic. At higher temperatures, and consequent SW:HF mixing ratios catabolic energy source at all temperatures (and SW:HF ratios) considered. The energetics of catabolism at the troctolite-basalt hybrid system were intermediate to these extremes. Reaction energetics for anabolism in chemolithoautotrophs—represented here by the synthesis of amino acids, nucleotides, fatty acids, saccharides, and amines—were generally most favorable at moderate temperatures (22-32 °C) and corresponding SW:HF mixing ratios (˜15). In peridotite-hosted and the troctolite-basalt hybrid systems, Δ G r for primary biomass synthesis yielded up to ˜900 J per g dry cell mass. The energetics of anabolism in basalt- and felsic rock-hosted systems were far less favorable. The results suggest that in peridotite-hosted (and troctolite-basalt hybrid) systems, compared with their basalt (and felsic rock) counterparts, microbial

  5. Chlorine isotope and Cl-Br fractionation in fluids of Poás volcano (Costa Rica): Insight into an active volcanic-hydrothermal system

    Science.gov (United States)

    Rodríguez, Alejandro; Eggenkamp, H. G. M.; Martínez-Cruz, María; van Bergen, Manfred J.

    2016-10-01

    Halogen-rich volcanic fluids issued at the surface carry information on properties and processes operating in shallow hydrothermal systems. This paper reports a long-term record of Cl-Br concentrations and δ37Cl signatures of lake water and fumaroles from the active crater of Poás volcano (Costa Rica), where surface expressions of magmatic-hydrothermal activity have shown substantial periodic changes over the last decades. Both the hyperacid water of its crater lake (Laguna Caliente) and subaerial fumaroles show significant temporal variability in Cl-Br concentrations, Br/Cl ratios and δ37Cl, reflecting variations in the mode and magnitude of volatile transfer. The δ37Cl signatures of the lake, covering the period 1985-2012, show fluctuations between + 0.02 ± 0.06‰ and + 1.15 ± 0.09‰. Condensate samples from adjacent fumaroles on the southern shore, collected during the interval (2010-2012) with strong changes in gas temperature (107-763°C), display a much larger range from - 0.43 ± 0.09‰ to + 14.09 ± 0.08‰. Most of the variations in Cl isotope, Br/Cl and concentration signals can be attributed to interaction between magma-derived gas and liquid water in the volcanic-hydrothermal system below the crater. The δ37Cl were lowest and closest to magmatic values in (1) fumarolic gas that experienced little or no interaction with subsurface water and followed a relatively dry pathway, and (2) water that captured the bulk of magmatic halogen output so that no phase separation could induce fractionation. In contrast, elevated δ37Cl can be explained by partial scavenging and fractionation during subsurface gas-liquid interaction. Hence, strong Cl isotope fractionation leading to very high δ37Cl in Poás' fumaroles indicates that they followed a wet pathway. Highest δ37Cl values in the lake water were found mostly in periods when it received a significant input from subaqueous fumaroles or when high temperatures and low pH caused HCl evaporation. It is

  6. Hydrothermal Biogeochemistry

    Science.gov (United States)

    Shock, E.; Havig, J.; Windman, T.; Meyer-Dombard, D.; Michaud, A.; Hartnett, H.

    2006-12-01

    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 system. 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 systems 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, hydrothermal ecosystems provide highly manageable opportunities for testing how biogeochemical processes respond to the scale of

  7. Caldera processes and magma-hydrothermal systems continental scientific drilling program: thermal regimes, Valles caldera research, scientific and management plan

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.; Nielson, D.L. (eds.)

    1986-05-01

    Long-range core-drilling operations and initial scientific investigations are described for four sites in the Valles caldera, New Mexico. The plan concentrates on the period 1986 to 1993 and has six primary objectives: (1) study the origin, evolution, physical/chemical dynamics of the vapor-dominated portion of the Valles geothermal system; (2) investigate the characteristics of caldera fill and mechanisms of caldera collapse and resurgence; (3) determine the physical/chemical conditions in the heat transfer zone between crystallizing plutons and the hydrothermal system; (4) study the mechanism of ore deposition in the caldera environment; (5) develop and test high-temperature drilling techniques and logging tools; and (6) evaluate the geothermal resource within a large silicic caldera. Core holes VC-2a (500 m) and VC-2b (2000 m) are planned in the Sulphur Springs area; these core holes will probe the vapor-dominated zone, the underlying hot-water-dominated zone, the boiling interface and probable ore deposition between the two zones, and the deep structure and stratigraphy along the western part of the Valles caldera fracture zone and resurgent dome. Core hole VC-3 will involve reopening existing well Baca number12 and deepening it from 3.2 km (present total depth) to 5.5 km, this core hole will penetrate the deep-crystallized silicic pluton, investigate conductive heat transfer in that zone, and study the evolution of the central resurgent dome. Core hole VC-4 is designed to penetrate deep into the presumably thick caldera fill in eastern Valles caldera and examine the relationship between caldera formation, sedimentation, tectonics, and volcanism. Core hole VC-5 is to test structure, stratigraphy, and magmatic evolution of pre-Valles caldera rocks, their relations to Valles caldera, and the influences of regional structure on volcanism and caldera formation.

  8. Integrated model of the shallow and deep hydrothermal systems in the East Mesa area, Imperial Valley, California

    Energy Technology Data Exchange (ETDEWEB)

    Riney, T.D.; Pritchett, J.W.; Rice, L.F.

    1982-01-01

    Geological, geophysical, thermal, petrophysical and hydrological data available for the East Mesa hydrothermal system that are pertinent to the construction of a computer model of the natural flow of heat and fluid mass within the system are assembled and correlated. A conceptual model of the full system 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 hydrothermal system, 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 system demonstrate that the vertical formation permeability of the deep East Mesa system 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.

  9. Microwave Hydrothermal Synthesis PZT of Nanometer Crystal

    Institute of Scientific and Technical Information of China (English)

    Hongxing LIU; Hong DENG; Yan LI; Yanrong LI

    2004-01-01

    It was focused on the applications and developments of microwave hydrothermal synthesis piezoelectric ceramic powder. The microwave hydrothermal vessel was designed and manufactured. The microwave hydrothermal synthesis system was established and the PZT piezoelectric ceramic powder was synthesized. XRD and TEM have been used to characterize the products in detail. The diameter of the PZT powder particle is from 40 to 60 nm.

  10. Diffuse emissions of Volatile Organic Compounds (VOCs) from soil in volcanic and hydrothermal systems: evidences for the influence of microbial activity on the carbon budget

    Science.gov (United States)

    Venturi, Stefania; Tassi, Franco; Fazi, Stefano; Vaselli, Orlando; Crognale, Simona; Rossetti, Simona; Cabassi, Jacopo; Capecchiacci, Francesco

    2017-04-01

    Soils in volcanic and hydrothermal areas are affected by anomalously high concentrations of gases released from the deep reservoirs, which consists of both inorganic (mainly CO2 and H2S) and organic (volatile organic compounds; VOCs) species. VOCs in volcanic and hydrothermal fluids are mainly composed of saturated and unsaturated hydrocarbons (alkanes, aromatics, alkenes, and cyclics), with variable concentrations of O- and S-bearing compounds and halocarbons, depending on the physicochemical conditions at depth. VOCs in interstitial soil gases and fumarolic emissions from four volcanic and hydrothermal systems in the Mediterranean area (Solfatara Crater, Poggio dell'Olivo and Cava dei Selci, in Italy, and Nisyros Island, in Greece) evidenced clear compositional differences, suggesting that their behavior is strongly affected by secondary processes occurring at shallow depths and likely controlled by microbial activity. Long-chain saturated hydrocarbons were significantly depleted in interstitial soil gases with respect to those from fumarolic discharges, whereas enrichments in O-bearing compounds (e.g. aldehydes, ketones), DMSO2 and cyclics were commonly observed. Benzene was recalcitrant to degradation processes, whereas methylated aromatics were relatively instable. The chemical and isotopic (δ13C in CO2 and CH4) composition of soil gases collected along vertical profiles down to 50 cm depth at both Solfatara Crater and Poggio dell'Olivo (Italy) showed evidences of relevant oxidation processes in the soil, confirming that microbial activity likely plays a major role in modifying the composition of deep-derived VOCs. Despite their harsh conditions, being typically characterized by high temperatures, low pH, and high toxic gases and metal contents, the variety of habitats characterizing volcanic and hydrothermal environments offers ideal biomes to extremophilic microbes, whose metabolic activity can consume and/or produce VOCs. In the Solfatara Crater, microbial

  11. Deep-sea hydrothermal vent bacteria related to human pathogenic Vibrio species

    National Research Council Canada - National Science Library

    Nur A. Hasan; Christopher J. Grim; Erin K. Lipp; Irma N. G. Rivera; Jongsik Chun; Bradd J. Haley; Elisa Taviani; Seon Young Choi; Mozammel Hoq; A. Christine Munk; Thomas S. Brettin; David Bruce; Jean F. Challacombe; J. Chris Detter; Cliff S. Han; Jonathan A. Eisen; Anwar Huq; Rita R. Colwell

    2015-01-01

    .... antiquarius is closely related to pathogenic Vibrio species, namely Vibrio alginolyticus, Vibrio parahaemolyticus, Vibrio harveyi, and Vibrio vulnificus, but sufficiently divergent to warrant a separate species status. The V...

  12. Exploring the structural controls on helium, nitrogen and carbon isotope signatures in hydrothermal fluids along an intra-arc fault system

    Science.gov (United States)

    Tardani, Daniele; Reich, Martin; Roulleau, Emilie; Takahata, Naoto; Sano, Yuji; Pérez-Flores, Pamela; Sánchez-Alfaro, Pablo; Cembrano, José; Arancibia, Gloria

    2016-07-01

    passage of the fluids through the upper crust. The degree of 4He contamination is strictly related with the faults controlling the occurrence of volcanic and geothermal systems, with the most contaminated values associated with NW-striking structures. This is confirmed by δ15N values that show increased mixing with crustal sediments and meteoric waters along NW faults (AFLS), while δ13C-CO2 data are indicative of cooling and mixing driving calcite precipitation due to increased residence times along such structures. Our results show that the structural setting of the region exerts a fist-order control on hydrothermal fluid composition by conditioning residence times of magmas and thus promoting cooling/mixing of magmatic vapor, and therefore, must be taken into consideration for further geochemical interpretations.

  13. Preparation of hollow silica nanospheres in O/W microemulsion system by hydrothermal temperature changes

    Science.gov (United States)

    Wang, Dandan; Li, Xiuyan; Liu, Zuohua; Shi, Xue; Zhou, Guowei

    2017-01-01

    Hollow silica nanospheres with wrinkled or smooth surfaces were successfully fabricated through a hydrothermal 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 hydrothermal 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.

  14. Rare earth elements as indicators of hydrothermal processes within the East Scotia subduction zone system

    Science.gov (United States)

    Cole, Catherine S.; James, Rachael H.; Connelly, Douglas P.; Hathorne, Ed C.

    2014-09-01

    The East Scotia subduction zone, located in the Atlantic sector of the Southern Ocean, hosts a number of hydrothermal sites in both back-arc and island-arc settings. High temperature (>348 °C) 'black smoker' vents have been sampled at three locations along segments E2 and E9 of the East Scotia back-arc spreading ridge, as well as 'white smoker' (Mg = 0 mmol/kg) is markedly different, with pH ranging from andesite-hosted, providing an ideal opportunity for investigating the geochemical controls on rare earth element (REE) behaviour. Endmember hydrothermal fluids from E2 and E9 have total REE concentrations ranging from 7.3 to 123 nmol/kg, and chondrite-normalised distribution patterns are either light REE-enriched (LaCN/YbCN = 12.8-30.0) with a positive europium anomaly (EuCN/Eu∗CN = 3.45-59.5), or mid REE-enriched (LaCN/NdCN = 0.61) with a negative Eu anomaly (EuCN/Eu∗CN = 0.59). By contrast, fluids from the Kemp Caldera have almost flat REE patterns (LaCN/YbCN = 2.1-2.2; EuCN/Eu∗CN = 1.2-2.2). We demonstrate that the REE geochemistry of fluids from the East Scotia back-arc spreading ridge is variably influenced by ion exchange with host minerals, phase separation, competitive complexation with ligands, and anhydrite deposition, whereas fluids from the Kemp submarine volcano are also affected by the injection of magmatic volatiles which enhances the solubility of all the REEs. We also show that the REE patterns of anhydrite deposits from Kemp differ from those of the present-day fluids, potentially providing critical information about the nature of hydrothermal activity in the past, where access to hydrothermal fluids is precluded.

  15. Study of Hydrothermal Particulate Matter from a Shallow Venting System, offshore Nayarit, Mexico

    Science.gov (United States)

    Ortega-Osorio, A.; Prol-Ledesma, R. M.; Reyes, A. G.; Rubio-Ramos, M. A.; Torres-Vera, M. A.

    2001-12-01

    A shallow (30 ft) hydrothermal 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 hydrothermal fluid, gas, rocks, and particulate matter were collected directly from the vent. Water samples and hydrothermal 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 hydrothermal 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

  16. Did a whole-crustal hydrothermal system generate the Irish Zn-Pb orefield?

    Science.gov (United States)

    Daly, J. Stephen; Badenszki, Eszter; Chew, David; Kronz, Andreas; O'Rourke, Helen; Whitehouse, Martin; Menuge, Julian; van den Berg, Riana

    2016-04-01

    Current models[1] for the genesis of the giant Irish Carboniferous-hosted Zn-Pb orefield propose shallow (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 hydrothermal fluid system operating at least to depths of ~ 25km. References [1] Wilkinson, J.J. & Hitzman, M.W. 2015. The Irish Pb-Zn orefield: The view from 2014. In: Archibald, S.M. and Piercey, S.J. (eds) Current Perspectives on Zinc deposits. Irish Association for Economic Geology, pp. 59-72.; [2] Davidheiser-Kroll, B., Stuart, F.M. & Boyce, A.J. 2014. Mineralium Deposita, 49, 547-553; [3] Elliott, H. 2015. Unpublished PhD thesis, University of Southampton; [4] Hnatyshin, D., Creaser, R.A., Wilkinson, J.J. & Gleeson, S.A. 2015. Geology, 43, 143-146; [5] McCusker, J. & Reed, C. 2013. Mineralium Deposita, 48, 687-695; [6] Van den Berg, R., Daly, J.S. & Salisbury, M.H. 2005. Tectonophysics, 407(1-2), 81-99; [7] Hauser, F., O'Reilly, B.M., Readman, P.W., Daly, J. S. & Van den Berg, R. 2008. Geophysical Journal International 175, 1254-1272; [8] Walshaw, R.D., Menuge, J.F. & Tyrrell, S. 2006. Mineralium Deposita, 41, 803-819; [9] Everett, C

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

    Science.gov (United States)

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

    2016-04-01

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

  18. Mercury isotopic composition of hydrothermal systems in the Yellowstone Plateau volcanic field and Guaymas Basin sea-floor rift

    Science.gov (United States)

    Sherman, L.S.; Blum, J.D.; Nordstrom, D.K.; McCleskey, R.B.; Barkay, T.; Vetriani, C.

    2009-01-01

    To characterize mercury (Hg) isotopes and isotopic fractionation in hydrothermal systems we analyzed fluid and precipitate samples from hot springs in the Yellowstone Plateau volcanic field and vent chimney samples from the Guaymas Basin sea-floor rift. These samples provide an initial indication of the variability in Hg isotopic composition among marine and continental hydrothermal systems that are controlled predominantly by mantle-derived magmas. Fluid samples from Ojo Caliente hot spring in Yellowstone range in δ202Hg from - 1.02‰ to 0.58‰ (± 0.11‰, 2SD) and solid precipitate samples from Guaymas Basin range in δ202Hg from - 0.37‰ to - 0.01‰ (± 0.14‰, 2SD). Fluid samples from Ojo Caliente display mass-dependent fractionation (MDF) of Hg from the vent (δ202Hg = 0.10‰ ± 0.11‰, 2SD) to the end of the outflow channel (&delta202Hg = 0.58‰ ± 0.11‰, 2SD) in conjunction with a decrease in Hg concentration from 46.6pg/g to 20.0pg/g. Although a small amount of Hg is lost from the fluids due to co-precipitation with siliceous sinter, we infer that the majority of the observed MDF and Hg loss from waters in Ojo Caliente is due to volatilization of Hg0(aq) to Hg0(g) and the preferential loss of Hg with a lower δ202Hg value to the atmosphere. A small amount of mass-independent fractionation (MIF) was observed in all samples from Ojo Caliente (Δ199Hg = 0.13‰ ±1 0.06‰, 2SD) but no significant MIF was measured in the sea-floor rift samples from Guaymas Basin. This study demonstrates that several different hydrothermal processes fractionate Hg isotopes and that Hg isotopes may be used to better understand these processes.

  19. Contribution to the operating energy planning of hydrothermal power systems; Contribuicao ao planejamento da operacao energetica de sistemas hidrotermicos de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Adriano Alber de Franca Mendes

    1991-08-01

    This work treats of the problem of the planning of the energy operation of hydrothermal power systems, gone back to those with predominance of hydraulic generation, as it is the case of the Brazilian system. The work makes an analysis of the problem of the planning of the energy operation of systems hydrothermal leaving of the concepts and nature of this problem. Their inherent difficulties are shown and they come the main approaches in operation in countries with predominance of hydroelectric generation. It still introduces the methodology in energy planning in Brazil being pointed their main limitations. Finally an alternative model for the planning of the energy operation of the system brazilian hydrothermal, based on the made studies is also presented.

  20. Constraints on the Lost City Hydrothermal System from borehole thermal data; 3-D models of heat flow and hydrothermal circulation in an oceanic core complex.

    Science.gov (United States)

    Titarenko, S.; McCaig, A. M.

    2014-12-01

    A perennial problem in near-ridge hydrothermal circulation is that the only directly measurable data to test models is often vent fluid temperature. Surface heat flow measurements may be available but without the underlying thermal structure it is not known if they are transient and affected by local hydrothermal flow, or conductive. The Atlantis Massif oceanic core complex at 30 °N on the mid-Atlantic Ridge, offers a unique opportunity to better constrain hydrothermal circulation models. The temperature profile in gabbroic rocks of IODP Hole 1309D was measured in IODPExpedition 340T, and found to be near-conductive, but with a slight inflexion at ~750 mbsf indicating downward advection of fluid above that level. The lack of deep convection is especially remarkable given that the long-lived Lost City Hydrothermal Field (LCHF) is located only 5km to the south. We have modelled hydrothermal circulation in the Massif using Comsol Multiphysics, comparing 2-D and 3-D topographic models and using temperature-dependent conductivity to give the best estimate of heatflow into the Massif. We can constrain maximum permeability in gabbro below 750 mbsf to 5e-17 m2. The thermal gradient in the upper part of the borehole can be matched with a permeability of 3e-14 m2 in a 750 m thick layer parallel to the surface of the massif, with upflow occurring in areas of high topography and downflow at the location of the borehole. However in 3-D the precise flow pattern is quite model dependent, and the thermal structure can be matched either by downflow centred on the borehole at lower permeability or centred a few hundred metres from the borehole at higher permeability. The borehole gradient is compatible with the longevity (>120 kyr) and outflow temperature (40-90 °C) of the LCHF either with a deep more permeable (1e-14 m2 to 1e-15 m2) domain beneath the vent site in 2-D or a permeable fault slot 500 to 1000m wide and parallel to the transform fault in 3-D. In both cases topography

  1. High resolution mapping of hydrothermal plumes in the Mariana back-arc relate seafloor sources to above-bottom plumes

    Science.gov (United States)

    Walker, S. L.; Baker, E. T.; Resing, J. A.; Chadwick, W. W., Jr.; Merle, S. G.; Kaiser, C. L.

    2016-12-01

    The Mariana backarc spreading center between 12.9°-18°N was systematically explored for hydrothermal activity in Nov-Dec 2015 (R/V Falkor cruise FK151121) by conducting long distance along-axis CTD tows (vertical range was 20-600 meters above bottom (mab)) followed by higher resolution, horizontal grid AUV Sentry surveys at 70 mab in some of the areas where plumes were found. In those areas, the combination of along-axis CTD tows and near-bottom AUV surveys provides a nearly 3-dimensional view of the above-bottom plume relative to the seafloor morphology and potential sources. In addition, photo surveys were run at 5 mab at two of the sites. At 15.4°N, strong ORP anomalies (ΔE=-39 mv) with weak to absent optical signals were aligned with a new (ROV dives in May 2016. At 18°N, anomalies seen in the 11 km2 AUV survey were generally located along the axis of the spreading center and, with one exception, were limited to areas of previously-known (1987) venting. The plume in the water column over the Burke vent site was defined by both particle (dNTU=0.010) and ORP (ΔE=-11 mv) anomalies from 400-800 mab, but only ORP signals 120-400 mab. ORP signals were seen over the other sites without any optical anomalies; the much lower rise heights (200-400 mab) suggest only lower temperature, diffuse venting persists at these sites.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kasameyer, P.

    1980-09-02

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

  3. Synthesis of Hydrotalcite-like Compound Pillared by Hetero-polyacid Anions in a Hydrothermal System

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hetero-polyacid anions (PW12O403-)-pillared hydrotalcite-like compound is directly and hydrothermally synthesized by the hot solution method. FTIR and XRD show that PW12O403- has been incorporated into the interstitial space with the dimension of 0.917 nm. The state of PW12O403- anion between the hydrotalcite sheets was also discussed. The title product can be expressed by formula [Zn0.68Al0.32(OH)2][PW12O40] 0. 113H2O after a serious study of TGA and chemical analysis.

  4. A Galerkin, finite-element analysis of steady-state flow and heat transport in the shallow hydrothermal system in the East Mesa area, Imperial Valley, California

    Science.gov (United States)

    Miller, R.E.

    1977-01-01

    A steady-state simulation model was applied to the shallow hydrothermal system in the East Mesa area of Imperial Valley, Calif. The steady-state equations of flow and heat transport were solved by use of a Galerkin, finite-element method. A solution was obtained by iterating between the temperature and pressure equations, using updated densities and viscosities. Temperature and pressure were obtained for each node, and corresponding head values were calculated. The simulated temperature and pressure patterns correlated well with the observed patterns. Additional data, mainly from test drilling, would be required for construction of a similar model of the deep hydrothermal system.

  5. Hydrothermal synthesis of BaTiO 3 nanoparticles using a supercritical continuous flow reaction system

    Science.gov (United States)

    Hayashi, Hiromichi; Noguchi, Takio; Islam, Nazrul M.; Hakuta, Yukiya; Imai, Yusuke; Ueno, Nobuhiko

    2010-06-01

    Highly crystalline BaTiO 3 nanoparticle was synthesized rapidly by hydrothermal reaction in supercritical water using a continuous flow reactor. The reactants of TiO 2 sol (or TiCl 4)/Ba(NO 3) 2 mixed solution and KOH solution were used as starting materials and that was heated quickly up to 400 °C under the pressure of 30 MPa for 8 ms as reaction time. The XRD results revealed that the crystal phase of the obtained particles was cubic BaTiO 3, indicating that the hydrothermal reaction in supercritical water was successfully proceeded under present reaction conditions. Primarily particle size of the BaTiO 3 nanoparticle was determined by means of BET surface area, as small as less than 10 nm with decreasing the reaction pH. In contrast, dispersed particle size in solution measured by DLS (dynamic light scattering) technique decreased from 260 to 90 nm with increasing the reactants concentration. Aggregation of BaTiO 3 nanoparticles might be depressed in the presence of coexisting nitrate anions.

  6. Hydrothermal Reactivity of Amines

    Science.gov (United States)

    Robinson, K.; Shock, E.; Hartnett, H. E.; Williams, L. B.; Gould, I.

    2013-12-01

    The reactivity of aqueous amines depends on temperature, pH, and redox state [1], all of which are highly variable in hydrothermal systems. Temperature and pH affect the ratio of protonated to unprotonated amines (R-NH2 + H+ = R-NH3+), which act as nucleophiles and electrophiles, respectively. We hypothesize that this dual nature can explain the pH dependence of reaction rates, and predict that rates will approach a maximum at pH = pKa where the ratio of protonated and unprotonated amines approaches one and the two compounds are poised to react with one another. Higher temperatures in hydrothermal systems allow for more rapid reaction rates, readily reversible reactions, and unique carbon-nitrogen chemistry in which water acts as a reagent in addition to being the solvent. In this study, aqueous benzylamine was used as a model compound to explore the reaction mechanisms, kinetics, and equilibria of amines under hydrothermal conditions. Experiments were carried out in anoxic silica glass tubes at 250°C (Psat) using phosphate-buffered solutions to observe changes in reaction rates and product distributions as a function of pH. The rate of decomposition of benzylamine was much faster at pH 4 than at pH 9, consistent with the prediction that benzylamine acts as both nucleophile and an electrophile, and our estimate that the pKa of benzylamine is ~5 at 250°C and Psat. Accordingly, dibenzylamine is the primary product of the reaction of two benzylamine molecules, and this reaction is readily reversible under hydrothermal conditions. Extremely acidic or basic pH can be used to suppress dibenzylamine production, which also suppresses the formation of all other major products, including toluene, benzyl alcohol, dibenzylimine, and tribenzylamine. This suggests that dibenzylamine is the lone primary product that then itself reacts as a precursor to produce the above compounds. Analog experiments performed with ring-substituted benzylamine derivatives and chiral

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

    Science.gov (United States)

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

    2008-12-01

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

  8. Environmental controls on biomineralization and Fe-mound formation in a low-temperature hydrothermal system at the Jan Mayen Vent Fields

    Science.gov (United States)

    Johannessen, Karen C.; Vander Roost, Jan; Dahle, Håkon; Dundas, Siv H.; Pedersen, Rolf B.; Thorseth, Ingunn H.

    2017-04-01

    Diffuse low-temperature hydrothermal vents on the seafloor host neutrophilic microaerophilic Fe-oxidizing bacteria that utilize the Fe(II) supplied by hydrothermal fluids and produce intricate twisted and branching extracellular stalks. The growth behavior of Fe-oxidizing bacteria in strongly opposing gradients of Fe(II) and O2 have been thoroughly investigated in laboratory settings to assess whether extracellular stalks and aligned biomineralized fabrics may serve as biosignatures of Fe-oxidizing bacteria and indications of palaeo-redox conditions in the rock record. However, the processes controlling the growth of biogenic Fe-oxyhydroxide deposits in natural, modern hydrothermal systems are still not well constrained. In this study, we aimed to establish how variations in the texture of stratified hydrothermal Fe-oxyhydroxide deposits are linked to the physicochemical conditions of the hydrothermal environment. We conducted 16S rRNA gene analyses, microscopy and geochemical analyses of laminated siliceous Fe-mounds from the Jan Mayen Vent Fields at the Arctic Mid-Ocean Ridge. Chemical analyses of low- and high-temperature hydrothermal fluids were performed to characterize the hydrothermal system in which the Fe-deposits form. Our results reveal synchronous inter-laminar variations in texture and major and trace element geochemistry. The Fe-deposits are composed of alternating porous laminae of mineralized twisted stalks and branching tubes, Mn-rich horizons with abundant detrital sediment, domal internal cavities and thin P- and REE-enriched lamina characterized by networks of ≪1 μm wide fibers. Zetaproteobacteria constitute one third of the microbial community in the surface layer of actively forming mounds, indicating that microbial Fe-oxidation is contributing to mound accretion. We suggest that Mn-oxide precipitation and detrital sediment accumulation take place during periodically low hydrothermal fluid discharge conditions. The elevated concentrations

  9. Two series of copper-gold deposits in the middle and lower reaches of the Yangtze River area (MLYRA) and the hydrogen, oxygen, sulfur and lead isotopes of their ore-forming hydrothermal systems

    Institute of Scientific and Technical Information of China (English)

    周涛发; 袁峰; 岳书仓; 赵勇

    2000-01-01

    Based on studies on the geological characteristics of the copper-gold deposits in the middle and lower reaches of the Yangtze River area (MLYRA) and their hydrogen, oxygen, sulfur and lead isotope compositions, it is concluded that there existed two series of copper-gold deposits. They are evolutional products of two ore-forming hydrothermal systems in different geodynamic settings and geological era. Series I is stratiform or stratabound copper-gold deposits. These deposits were formed by submarine exhalation and sedimentation of hydrothermal solutions in Her-cynian tensional tectonic environment after bot brine ascending along contemporaneous faults and exhaled into the sea-floor. Series II consists of copper-gold deposits related to medium and acidic magmatic intrusions. Their mineralizations took place in Yanshanian in a tensional or a transitional period to the tensional tectonic environment from the composite of the tethys tectonic regime and the Paleo-Pacific ocean tectonic regime, as well as in

  10. Reactions between komatiite and CO2-rich seawater at 250 and 350 °C, 500 bars: implications for hydrogen generation in the Hadean seafloor hydrothermal system

    Science.gov (United States)

    Ueda, Hisahiro; Shibuya, Takazo; Sawaki, Yusuke; Saitoh, Masafumi; Takai, Ken; Maruyama, Shigenori

    2016-12-01

    To understand the chemical nature of hydrothermal fluids in the komatiite-hosted seafloor hydrothermal system in the Hadean, we conducted two hydrothermal serpentinization experiments involving synthetic komatiite and a CO2-rich acidic NaCl fluid at 250 and 350 °C, 500 bars. During the experiments, the komatiites were strongly carbonated to yield iron-rich dolomite (3-9 wt.% FeO) at 250 °C and calcite (<0.8 wt.% FeO) at 350 °C, respectively. The carbonation of komatiites suppressed H2 generation in the fluids. The steady-state H2 concentrations in the fluid were approximately 0.024 and 2.9 mmol/kg at 250 and 350 °C, respectively. This correlation between the Fe content in carbonate mineral and the H2 concentration in the fluid suggests that the incorporation of ferrous iron into the carbonate mineral probably limited magnetite formation and consequent generation of hydrogen during the serpentinization of komatiites. The H2 concentration of the fluid at 350 °C corresponds to that of modern H2-rich seafloor hydrothermal systems, such as the Kairei hydrothermal field, where hydrogenotrophic methanogens dominate in the prosperous microbial ecosystem. Accordingly, the high-temperature serpentinization of komatiite would provide the H2-rich hydrothermal environments that were necessary for the emergence and early evolution of life in the Hadean ocean. In contrast, H2-rich fluids may not have been generated by serpentinization at temperatures below 250 °C because carbonate minerals become more stable with decreasing temperature in the komatiite-H2O-CO2 system.

  11. Hydrothermal minerals

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.

    -floor hydrothermal processes involving free circulation of seawater through ocean crust as convection. Heat flow, seafloor fracturing, permeability and fluid composition are the parameters governing the type and extent of mineralization. The chimney like... stream_size 23365 stream_content_type text/plain stream_name Refresher_Course_Mar_Geol_Geophys_2007_Lecture_Notes_78.pdf.txt stream_source_info Refresher_Course_Mar_Geol_Geophys_2007_Lecture_Notes_78.pdf.txt Content-Encoding UTF-8...

  12. Thermodynamics of Fe(II)Fe(III) oxide systems I. Hydrothermal Fe3O4

    Science.gov (United States)

    Bartel, J.J.; Westrum, E.F.; Haas, J.L.

    1976-01-01

    The heat capacity of a hydrothermally-prepared polycrystalline sample of Fe3O4 was measured from 53 to 350 K, primarily to study the thermophysics of the Verwey transitions. Although the bifurcation of the transition was confirmed, the sample was found to contain traces of manganese. The observed transition temperatures of 117.0 and 123.0 K are 3.7 and 4.2 K higher respectively than those found in pure Fe3O4. Ancillary analytical results are consistent and indicate a stoichiometry of Mn0.008Fe2.992O4 for this material. Characteristics in the transition region are ascribed to dopant effects. ?? 1976.

  13. Sr isotopes in the Orgueil CI meteorite: Chronology of early solar system hydrothermal activity

    Indian Academy of Sciences (India)

    J D Macdougall

    2000-03-01

    New Sr isotopic analyses and calculated formation ages of carbonates from the Orgueil CI meteorite are reported. Among the samples analyzed in this work, dolomites give the youngest formation ages and may have been deposited intermittently starting near the time of parent body formation and continuing for at least 30 Ma. The Sr isotope data also suggest that breunnerites (Fe-Mn-Mg carbonates) crystallized after dolomite formation. Leaching experiments on bulk meteorite samples provide evidence for a very mobile, water soluble Sr reservoir in Orgueil that is characterized by extremely radiogenic Sr (87Sr/86Sr ≈ 0.81- 0.82). This unsupported Sr reflects recent element redistribution, possibly at the time of parent body breakup recorded by the ∼10 Ma exposure age of Orgueil. The carbonate data in particular corroborate earlier indications that hydrothermal processes were among the earliest events to affect the CI parent body.

  14. Coupling mechanism of mineralization and hydrocarbon-forming in hydrothermal convection system: An example from Longtoushan Sn-polymetal deposit, Dachang

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; PENG Sheng-lin; YANG Mu; ZHANG Qi-zuan

    2005-01-01

    Longtoushan Sn-polymetal deposit is a large-scale deposit of high-tenor. The ore-bodies occur in reef limestone of middle Devonian. There is much anthraxolite in reef limestone and ore-bodies. The anthraxolite is the postmature result of oil-gas' thermal metamorphism. The close relationship of anthraxolite and Sn-polymetal deposit reveals the space-time relation between oil-gas evolution and Sn-polymetal mineralization. Sulfur isotope of Longtoushan deposit is close to oil's sulfur in Devonian, which indicates obvious relationship between the sulfur's source of deposit and oil-gas' activity. The forming of Longtoushan deposit relates to exhalative-sedimentary mineralization in Devonian. Because of the favorable hydrocarbon-forming condition of Longtoushan reef and surrounding basin facies' black shale and peat, coupling of ore-formation and hydrocarbon-forming occurs in seabed's hydrothermal convection. The distributing of ore-forming elements indicates the presence of hydrothermal convection system. The thermal fluid containing organic matters conduces to Sn-polymetal elements' activation and transfer, and provides catalyzing condition to the transforming from SO42- to S2-. The erosion action of brine containing organic acid to reef limestone induces the growing of crannies and karst's caverns, which provides advantageous space to Sn-polymetal mineralization. The heat source of mineralization provides thermocatalysis condition to hydrocarbon-forming. When the circulatory fluid containing oil-gas enters the high-temperature region(>150 ℃ ), the oil-gas is decomposed and anthraxolite comes into being.

  15. A Geographical Information System to Manage the Endeavour Hydrothermal Vents Marine Protected Area

    Science.gov (United States)

    Douglas, K. L.; Hillier, M. C. J.; Thornborough, K. J.; Jenkyns, R.; Juniper, K.

    2016-02-01

    The Endeavour Hydrothermal Vents Marine Protected Area (EHVMPA) is located approximately 250 km offshore of Vancouver Island, British Columbia. Since its discovery in 1982, there have been hundreds of dives, samples collected, measurements made, and debris left behind at the EHVMPA. In 2003, the Canadian government declared the region as a Marine Protected Area (MPA) under Canada's Oceans Act, to be managed by the Department of Fisheries and Oceans (DFO). Ocean Networks Canada (ONC) operates a cabled observatory in the EHVMPA, and streams data in near real-time via the Internet to science communities worldwide. ONC's observatory data, combined with observations made during maintenance expeditions provides insight assisting the management and preservation of the MPA. In 2014, DFO partnered with ONC to build a geodatabase to enhance and inform the knowledge base of the EHVMPA Management Plan. The geodatabase, built in ArcGIS, contains data integrated from ONC's Oceans 2.0 database, third parties, and relevant publications. Layers include annual observatory infrastructure deployments, remotely operated vehicle (ROV) dive tracks, sampling activity, anthropogenic debris, high-resolution bathymetry, observations of species of interest, and locations of hydrothermal vents. The combined data show both efforts to better understand the environment and the resulting stressors that impact the MPA. The tool also links observed features such as debris and biological observations to the time-correlated ROV dive video using ONC's SeaTube video viewing tool allowing for further analysis. Through 2017, the geodatabase will be maintained by ONC and enriched with expedition data from organizations such as Monterey Bay Aquarium Research Institute, Woods Hole Oceanographic Institute, and the University of Washington. The end result is a tool that can integrate many types of data obtained from the MPA, and encourages systematic management of a remote, dynamic and fragile environment.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stein, J.S.; Fisher, A.T. [Univ. of California, Santa Cruz, CA (United States); Langseth, M.; Jin, W.; Iturrino, G. [Lamont-Doherty Earth Observatory, Palisades, NY (United States); Davis, E. [Geological Survey of Canada, Sidney, British Columbia (Canada). Pacific Geoscience Centre

    1998-12-01

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

  17. Geothermal reservoir engineering 4. Heat and mass transfer in hydrothermal systems; Chinetsu choryuso kogaku. Dai 4 kai nessui tairyukei no netsu/shitsuryo yuso

    Energy Technology Data Exchange (ETDEWEB)

    Ishido, T. [Geological Survey of Japan, Tsukuba, Ibaraki (Japan)

    1997-12-01

    The underground geothermal reservoir is a part of the hydrothermal systems, its openness is strong and its shape is irregular, hence it is necessary to obtain sufficiently such various data as pressure transition tests in order to construct a model, in particular a mathematical model, of a geothermal reservoir. In order to prepare a quantitative reservoir model by numerical simulation, the basic understanding is indispensable on the flow of heat and fluid in the hydrothermal system. In this article, explanations are made on the following items based on the above recognition. They are the flow of earth crust fluid (the flow driven hydraulically and the flow driven by heat), generation of unstability (Rayleigh-Darcy instability, and double advection-diffusion instability), circulation and heat convection associated with terrain corrugation (convection pattern, Nusselt number and transition time of convection development) and modelization of geothermal system (hydrothermal system of a big scale associated with cooling of intrusive rock, development of reservoir controlled by fault, and hydrothermal convection system associated with magma activity). 26 refs., 26 figs.

  18. Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy

    Directory of Open Access Journals (Sweden)

    Francesco Mazzarini

    2014-06-01

    Full Text Available Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.

  19. The Rock Physics of Fiber-Reinforced Rocks Helps Explain Uplifts at Campi Flegrei Volcano-Hydrothermal System

    Science.gov (United States)

    Vanorio, T.; Kanitpanyacharoen, W.

    2015-12-01

    The caldera of Campi Flegrei is one of the active volcano-hydrothermal systems of the Mediterranean region experiencing notable unrest episodes in a densely populated area. One peculiar trait characterizes the unrest of this system: the ability of withstanding large uplifts before setting off a swarm of microeartquakes. Therefore, one core question is how the subsurface rocks of Campi Flegrei withstand such a large strain and have high strength. The rock physics analysis of well cores up to 3 km provides evidence for the existence of two horizons, above and below the seismogenic area, underlying a natural, coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The impermeable caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix made of intertwining filaments of ettringite and tobemorite, resulting from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that of the engineering of the Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture. The importance of these findings lies not only on the fibrous and compositionally nature of the caprock but also on its possible physicochemical deterioration. Given the P-T-XCO2 conditions regulating the decarbonation reactions, possible influx of new brine into the Campi Flegrei system dilutes the existing CO2, thus triggering further decarbonation reaction. This leads to the formation of additional CO2, methane, and steam. As these gases rise toward the surface, they are halted by the natural concrete-like layer, which would lead to pore pressure increase and subsequent ground deformations.

  20. A multiobjective interval programming model for wind-hydrothermal power system dispatching using 2-step optimization algorithm.

    Science.gov (United States)

    Ren, Kun; Jihong, Qu

    2014-01-01

    Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision.

  1. A Multiobjective Interval Programming Model for Wind-Hydrothermal Power System Dispatching Using 2-Step Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Kun Ren

    2014-01-01

    Full Text Available Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision.

  2. Hydrothermally treated oil palm empty fruit bunch cellulose with urea and its dissolution in NaOH-Urea solvent system

    Science.gov (United States)

    Baharin, Khairunnisa Waznah; Zakaria, Sarani; Gan, Sinyee; Jaafar, Sharifah Nabihah Syed; Chia, Chin Hua

    2016-11-01

    Cellulose from Oil Palm Empty fruit bunch (OPEFB) fiber was hydrothermally treated by using autoclave which is immersed in an oil bath at 160 °C for 6 h. OPEFB cellulose was mixed with aqueous urea and stirred for 30 min to obtain a homogenous mixture before transferred into the autoclave. The effect of different cellulose to urea mass ratio (1:4, 1:6 and 1:8) on the molecular weight, degree of polymerization and solubility of the treated cellulose dissolved in NaOH and urea solvent system was studied. The result shows that the solubility of cellulose from OPEFB fiber increased while the molecular weight of cellulose decreased due to the pretreatment done on the OPEFB fiber.

  3. COINTEGRATION RELATIONSHIPS TO ESTIMATE THE MARGINAL COST OF DEFICIT IN PLANNING A HYDROTHERMAL SYSTEM: THE CASE OF BRAZIL

    Directory of Open Access Journals (Sweden)

    Lucio Guido Tapia Carpio

    2014-04-01

    Full Text Available The aim of this study is to analyze the behavior of gross domestic product (GDP compared to electricity consumption in Brazil to estimate the curve of deficit marginal cost. The deficit cost is used as exogenous parameter in the chain of models for planning the operation and expansion of a hydrothermal system as part of the total cost of operation. The results show a cointegration relationship between GDP and electricity consumption; therefore, there is a long-term equilibrium relationship between GDP and electricity consumption. This relationship is used to estimate the curve of deficit marginal cost. The possible short-term imbalance can be mitigated using the vector error correction model (VEC.

  4. Selected geothermal resources data: hydrothermal convection systems in the states of Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Renner, J.L.

    1976-02-01

    Data collected as part of the U.S. Geological Survey's research and land classification programs, from professional publications, and industry sources has been compiled in computer format. Location, surface manifestations, chemistry, physical properties, exploratory and development work, and references pertinent to 290 hydrothermal convection systems comprise the data base.

  5. Impact of hydrothermal alteration on the U-Pb isotopic system of zircons from the Fangcheng syenites in the Qinling orogen, Henan Province, China

    Institute of Scientific and Technical Information of China (English)

    BAO Zhiwei; WANG Qiang; BAI Guodian; ZHAO Zhenhua

    2009-01-01

    Disturbance of the zircon U-Pb isotopic system has been investigated extensively, but mostly in lab, in the last decades. Here, we reported a field-based study on intensive sericitization, K-feldsparthization and the impacts of mylonitization on zircons from the Fangcheng syenites.The Fangcheng syenites occur in the eastern part of the Qinling orogen and consist mainly of aegirine-augite syenite, aegirine nepheline syenite, biotite syenite and hornblende nepheline syenite. Zircons from the slightly sericitized aegirine augite syenite are colorless, transparent crystals and exhibit well-developed oscillatory and sector zoning on the cathodoluminescence (CL) images which are typical of magmatic zircons from alkaline rocks. Zircon U-Pb determinations by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) showed that the syenite was formed in Neoproterozoic time, the weighted average of 206Pb/238U ages is 844.3±1.6 Ma (MSWD=0.86). In contrast, the hydrothermally altered zircons (hydrothermal zircon) from the intensively sericitized, K-feldsparthized, and weakly mylonitized aegirine augite syenite are conglomerates, yellowish to brown in color, generally translucent and internally textureless. The CL and backscatter electron (BSE) images of hydrothermal zircons exhibit fractured, textureless or mosaic textures, and occasionally show "sponge texture" with the veinlets and inclusions of K-feldspar; however, relicts of magmatic oscillatory zoning can still be discerned locally in individual grains. LA-ICPMS analyses of the hydrothermal zircons demonstrated that the zircons are chemically inhomogeneous, with enhanced and widely varied Pb, U, and Th contents. The U and Th contents of the hydrothermal zircons are estimated to be 32×10-6-1550×10-6 and 188×10-6-4059×10-6, respectively, with Th/U ratios within the range of 0.7-44.9. 206Pb/238U apparent ages of the hydrothermal zircons are negatively correlated with the contents of U, and radiogenic and

  6. Reconstruction of the geology and structure of Lake Rotomahana and its hydrothermal systems from high-resolution multibeam mapping and seismic surveys: Effects of the 1886 Tarawera Rift eruption

    Science.gov (United States)

    de Ronde, C. E. J.; Walker, S. L.; LeBlanc, C.; Davy, B. W.; Fornari, D. J.; Tontini, F. Caratori; Scott, B. J.; Seebeck, H.; Stewart, T. J.; Mazot, A.; Nicol, A.; Tivey, M. A.

    2016-03-01

    formed during times of lower lake levels and gas pockmarks, all either related to the 1886 eruptive episode or post-eruption hydrothermal and erosional processes. Application of results from bubble plume, CO2 flux, magnetic and heat flux surveys of Lake Rotomahana to this study, when combined with regional earthquake relocation analysis and broadband magnetotelluric data, suggest an explanation in terms of a magmatic heat source located south of Waimangu and a corresponding convective water/heat transport system extending thence to beneath the western end of the lake. A holistic approach has provided a coherent context for the eruption and its effect on the historical Pink and White Terraces hydrothermal system that appears to have been the eastern-most extension of a larger system that lay beneath the Waimangu area before the eruption. The newly named Pink Terraces hydrothermal system (~ 1.5 km2) is a continuation of the historical hydrothermal activity that was concentrated on the western shores of the old lake, and together with the formation of the new, post-1886 Patiti hydrothermal system (~ 1 km2) located SW of Patiti Island, mark the two distinct areas of hydrothermal activity in the lake today.

  7. Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits

    Science.gov (United States)

    Diehl, S.F.; Hofstra, A.H.; Koenig, A.E.; Emsbo, P.; Christiansen, W.; Johnson, Chad

    2010-01-01

    In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au, or barite. Numerous occurrences of hydrothermal zebra dolomite (HZD), comprised of alternating layers of dark replacement and light void-filling sparry or saddle dolomite, are present in Paleozoic platform and slope carbonate rocks on the eastern side of the Great Basin physiographic province. Locally, it is associated with mineral deposits of barite, Ag-Pb-Zn, and Au. In this paper the spatial distribution of HZD occurrences, their stratigraphic position, morphological characteristics, textures and zoning, and chemical and stable isotopic compositions were determined to improve understanding of their age, origin, and relation to dolostone, ore deposits, and the tectonic evolution of the Great Basin. In northern and central Nevada, HZD is coeval and cogenetic with Late Devonian and Early Mississippian Sedex Au, Zn, and barite deposits and may be related to Late Ordovician Sedex barite deposits. In southern Nevada and southwest California, it is cogenetic with small MVT Ag-Pb-Zn deposits in rocks as young as Early Mississippian. Over Paleozoic time, the Great Basin was at equatorial paleolatitudes with episodes of arid paleoclimates. Several occurrences of HZD are crosscut by Mesozoic or Cenozoic intrusions, and some host younger pluton-related polymetallic replacement and Carlin-type gold deposits. The distribution of HZD in space (carbonate platform, margin, and slope) and stratigraphy (Late Neoproterozoic Ediacaran-Mississippian) roughly parallels that of dolostone and both are prevalent in Devonian strata. Stratabound HZD is best developed in Ediacaran and Cambrian units, whereas

  8. Hydrothermal contamination of public supply wells in Napa and Sonoma Valleys, California

    Science.gov (United States)

    Forrest, Matthew J.; Kulongoski, Justin T.; Edwards, Matthew S.; Farrar, Christopher D.; Belitz, Kenneth; Norris, Richard D.

    2013-01-01

    Groundwater chemistry and isotope data from 44 public supply wells in the Napa and Sonoma Valleys, California were determined to investigate mixing of relatively shallow groundwater with deeper hydrothermal fluids. Multivariate analyses including Cluster Analyses, Multidimensional Scaling (MDS), Principal Components Analyses (PCA), Analysis of Similarities (ANOSIM), and Similarity Percentage Analyses (SIMPER) were used to elucidate constituent distribution patterns, determine which constituents are significantly associated with these hydrothermal systems, and investigate hydrothermal contamination of local groundwater used for drinking water. Multivariate statistical analyses were essential to this study because traditional methods, such as mixing tests involving single species (e.g. Cl or SiO2) were incapable of quantifying component proportions due to mixing of multiple water types. Based on these analyses, water samples collected from the wells were broadly classified as fresh groundwater, saline waters, hydrothermal fluids, or mixed hydrothermal fluids/meteoric water wells. The Multivariate Mixing and Mass-balance (M3) model was applied in order to determine the proportion of hydrothermal fluids, saline water, and fresh groundwater in each sample. Major ions, isotopes, and physical parameters of the waters were used to characterize the hydrothermal fluids as Na–Cl type, with significant enrichment in the trace elements As, B, F and Li. Five of the wells from this study were classified as hydrothermal, 28 as fresh groundwater, two as saline water, and nine as mixed hydrothermal fluids/meteoric water wells. The M3 mixing-model results indicated that the nine mixed wells contained between 14% and 30% hydrothermal fluids. Further, the chemical analyses show that several of these mixed-water wells have concentrations of As, F and B that exceed drinking-water standards or notification levels due to contamination by hydrothermal fluids.

  9. A multidisciplinary approach to quantify the permeability of the Whakaari/White Island volcanic hydrothermal system (Taupo Volcanic Zone, New Zealand)

    Science.gov (United States)

    Heap, Michael J.; Kennedy, Ben M.; Farquharson, Jamie I.; Ashworth, James; Mayer, Klaus; Letham-Brake, Mark; Reuschlé, Thierry; Gilg, H. Albert; Scheu, Bettina; Lavallée, Yan; Siratovich, Paul; Cole, Jim; Jolly, Arthur D.; Baud, Patrick; Dingwell, Donald B.

    2017-02-01

    Our multidisciplinary study aims to better understand the permeability of active volcanic hydrothermal systems, a vital prerequisite for modelling and understanding their behaviour and evolution. Whakaari/White Island volcano (an active stratovolcano at the north-eastern end of the Taupo Volcanic Zone of New Zealand) hosts a highly reactive hydrothermal system and represents an ideal natural laboratory to undertake such a study. We first gained an appreciation of the different lithologies at Whakaari and (where possible) their lateral and vertical extent through reconnaissance by land, sea, and air. The main crater, filled with tephra deposits, is shielded by a volcanic amphitheatre comprising interbedded lavas, lava breccias, and tuffs. We deployed field techniques to measure the permeability and density/porosity of (1) > 100 hand-sized sample blocks and (2) layered unlithified deposits in eight purpose-dug trenches. Our field measurements were then groundtruthed using traditional laboratory techniques on almost 150 samples. Our measurements highlight that the porosity of the materials at Whakaari varies from ∼ 0.01 to ∼ 0.7 and permeability varies by eight orders of magnitude (from ∼ 10-19 to ∼ 10-11 m2). The wide range in physical and hydraulic properties is the result of the numerous lithologies and their varied microstructures and alteration intensities, as exposed by a combination of macroscopic and microscopic (scanning electron microscopy) observations, quantitative mineralogical studies (X-ray powder diffraction), and mercury porosimetry. An understanding of the spatial distribution of lithology and alteration style/intensity is therefore important to decipher fluid flow within the Whakaari volcanic hydrothermal system. We align our field observations and porosity/permeability measurements to construct a schematic cross section of Whakaari that highlights the salient findings of our study. Taken together, the alteration typical of a volcanic

  10. Bioavailability, Bioaccumulation and Biotransformation of arsenic in coral reef organisms surrounding an arsenic-rich marine shallow-water hydrothermal vent system in the coastal waters of Ambitle Island, Papua New Guinea

    Science.gov (United States)

    Pichler, T.; Wallschläger, D.; Price, R. E.

    2009-12-01

    Marine shallow-water hydrothermal systems are often enriched in biologically toxic elements, thus making them ideal natural analogs for coastal anthropogenic pollution. Here, we report our investigation of the bioavailability, bioaccumulation, and biotransformation of hydrothermally-derived arsenic into several coral reef organisms from the arsenic-rich marine shallow-water hydrothermal system of Tutum Bay, Ambitle Island, in northeastern Papua New Guinea. Hydrothermal venting provided bioavailable As by two major pathways throughout Tutum Bay: 1) easily-exchangeable As from hydrothermally influenced sediments to as far away as 200 m from focused venting, and 2) in surface seawaters, which may allow for biological uptake by phytoplankton and transfer up the food web. The soft coral Clavularia sp., the calcareous algae Halimeda sp., and the tunicate Polycarpa sp. collected from the hydrothermal area each displayed distinctly higher (up to 20 times) total arsenic compared to the control site, with increasing trends while approaching focused hydrothermal venting. Organic and inorganic arsenic species were extracted intact from the tissues of each organism, separated by anion exchange chromatography, and analyzed by inductively-coupled plasma-dynamic reaction cell-mass spectrometry. Overall, speciation patterns for Clavularia were similar for the control site versus the hydrothermal site, although the concentrations were much higher. Elevated concentrations of DMA and cationic forms of arsenic, most likely AB, in Clavularia, both from the control site and from the hydrothermal area suggest its metabolic pathway is not altered due to hydrothermal activity, and is similar to other marine organisms. Arsenic speciation patterns in Polycarpa were also similar for both sites, and suggests uptake of arsenic via food chain, containing neither As(III) nor As(V), but abundant excluded As and DMA. It is unclear if methylation is taking place within this organism or prior to

  11. Hydrothermal-flow regime and magmatic heat source of the Cerro Prieto geothermal system, Baja California, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.

    1982-01-01

    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 hydrothermal mineral zones and light stable isotopic ratios observed in rock samples from more than fifty deep wells, together with temperature gradients, wireline logs and other data. At the level so far penetrated by drilling, this hydrothermal system 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 shows that 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 of about 6 m/year through the pores of a typical cross section of the reservoir having an average porosity of 10%. Although this is an extensional tectonic environment of leaky transform faulting in which repeated intrusions of basalt magma are likely, for simplicity of computation possible heat sources were modelled as simple two dimensional basalt intrusions of various sizes, shapes and locations. We have calculated a series of two-dimensional convective heat transfer models, with different heat sources and permeability distributions. The models which produce the best fit for the temperature distributions observed in the field today have in common a heat source which is a funnel-shaped basalt intrusion, 4 km wide at the top, emplaced at a depth of 5 km to 6 km about 40,000 to 50,000 years ago.

  12. Micro-seismic earthquakes characteristics at natural and exploited hydrothermal systems in West Java, Indonesia

    Science.gov (United States)

    Jousset, P. G.; Jaya, M. S.; Sule, R.; Diningrat, W.; Gassner, A.; Akbar, F.; Ryannugroho, R.; Hendryana, A.; Kusnadi, Y.; Syahbana, D.; Nugraha, A. D.; Umar, M.; Indrinanto, Y.; Erbas, K.

    2013-12-01

    The assessment of geothermal resources requires the understanding of the structure and the dynamics of geothermal reservoirs. We deployed a multidisciplinary geophysical network around geothermal areas in the south of Bandung, West Java, Indonesia. The first deployment included a network of 30 broadband and 4 short-period seismic stations with Güralp and Trillium sensors (0.008 - 100 Hz) since October 2012. In a second step, we extended the network in June 2013 with 16 short-period (1 Hz) seismometers. We describe the set-up of the seismic networks and discuss first observations and results. 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 hydrothermal processes in this area. Preliminary location of earthquakes is performed using a non-linear algorithm, which allows us to define at least 3 seismic clusters. We discuss this seismic pattern within the geothermal fields.

  13. Thermodynamics of chemical free energy generation in off-axis hydrothermal vent systems and its consequences for compartmentalization and the emergence of life

    CERN Document Server

    Simoncini, E; Gallori, E; .,

    2010-01-01

    In this paper we demonstrate how chemical free energy can be produced by a geological process. We provide a thermodynamic framework in which to assess how life emerged at the off-axis hydrothermal vent system; the RNA - clays system has been investigated from the entropic point of view, showing that the stabilization of the system in a state further away from equilibrium state, by an inorganic heterogeneous compartmetalization phenomena, is able to produce chemical free energy useful for RNA self - replication.

  14. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Hoffmann, Jessica

    2014-01-01

    Biomass is one of the most abundant sources of renewable energy, and will be an important part of a more sustainable future energy system. In addition to direct combustion, there is growing attention on conversion of biomass into liquid en-ergy carriers. These conversion methods are divided...... into liquid biofuels, with the aim of describing the current status and development challenges of the technology. During the hydrothermal liquefaction process, the biomass macromolecules are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive...... into biochemical/biotechnical methods and thermochemical methods; such as direct combustion, pyrolysis, gasification, liquefaction etc. This chapter will focus on hydrothermal liquefaction, where high pressures and intermediate temperatures together with the presence of water are used to convert biomass...

  15. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Hoffmann, Jessica

    2014-01-01

    Biomass is one of the most abundant sources of renewable energy, and will be an important part of a more sustainable future energy system. In addition to direct combustion, there is growing attention on conversion of biomass into liquid en-ergy carriers. These conversion methods are divided...... into biochemical/biotechnical methods and thermochemical methods; such as direct combustion, pyrolysis, gasification, liquefaction etc. This chapter will focus on hydrothermal liquefaction, where high pressures and intermediate temperatures together with the presence of water are used to convert biomass...... into liquid biofuels, with the aim of describing the current status and development challenges of the technology. During the hydrothermal liquefaction process, the biomass macromolecules are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive...

  16. HRTEM/AEM study of trace metal behavior, sheet silicate reactions, and fluid/solid mass balances in porphyry copper hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Veblen, D.R.; Ilton, E.S.

    1989-04-01

    Transmission electron microscopy has been used to investigate copper (Cu) incorporation into silicates and alteration reactions in porphyry copper deposits. High Cu in biotites results from submicroscopic inclusions of native Cu. The incorporation of Cu in low-temperature alteration lamellae suggests that Cu enrichment occurs during weathering, rather than during the hydrothermal event. Drill core from Cyprus Casa Grande, Arizona, shows systematic variation of Cu in sheet silicates as a function of depth in the weathering column. The aims of the present project are to apply the powerful techniques of transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and analytical electron microscopy (AEM) to understanding the geochemical processes in porphyry copper systems at the near-atomic scale. Our primary goals are to characterize the structural state of anomalously high Cu in silicates, determine the timing and conditions of Cu enrichment in silicates such as biotite, and use these data to suggest how base metals are released and subsequently immobilized under hydrothermal or weathering conditions; and to determine the submicroscopic, atomic-level reaction mechanisms responsible for silicate alteration in porphyry-copper hydrothermal systems, which will allow us to determine reaction stoichiometries and hence mass balances between minerals and hydrothermal fluid. 19 refs., 7 figs., 3 tabs.

  17. A multitracer approach for characterizing interactions between shallow groundwater and the hydrothermal system in the Norris Geyser Basin area, Yellowstone National Park

    Science.gov (United States)

    Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.

    2011-01-01

    Multiple environmental tracers are used to investigate age distribution, evolution, and mixing in local- to regional-scale groundwater circulation around the Norris Geyser Basin area in Yellowstone National Park. Springs ranging in temperature from 3??C to 90??C in the Norris Geyser Basin area were sampled for stable isotopes of hydrogen and oxygen, major and minor element chemistry, dissolved chlorofluorocarbons, and tritium. Groundwater near Norris Geyser Basin is comprised of two distinct systems: a shallow, cool water system and a deep, high-temperature hydrothermal system. These two end-member systems mix to create springs with intermediate temperature and composition. Using multiple tracers from a large number of springs, it is possible constrain the distribution of possible flow paths and refine conceptual models of groundwater circulation in and around a large, complex hydrothermal system. Copyright 2011 by the American Geophysical Union.

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

    Science.gov (United States)

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

    2013-02-01

    Abstract Deep-sea ultramafic-hosted vent systems have the potential to provide large amounts of metabolic energy to both autotrophic and heterotrophic microorganisms in their dispersing hydrothermal plumes. Such vent-systems release large quantities of hydrogen and methane to the water column, both of which can be exploited by autotrophic microorganisms. Carbon cycling in these hydrothermal plumes may, therefore, have an important influence on open-ocean biogeochemistry. In this study, we investigated an ultramafic-hosted system on the Mid-Cayman Rise, emitting metal-poor and hydrogen sulfide-, methane-, and hydrogen-rich hydrothermal fluids. Total organic carbon concentrations in the plume ranged between 42.1 and 51.1 μM (background = 43.2 ± 0.7 μM (n = 5)) and near-field plume samples with elevated methane concentrations imply the presence of chemoautotrophic primary production and in particular methanotrophy. In parts of the plume characterized by persistent potential temperature anomalies but lacking elevated methane concentrations, we found elevated organic carbon concentrations of up to 51.1 μM, most likely resulting from the presence of heterotrophic communities, their extracellular products and vent larvae. Elevated carbon concentrations up to 47.4 μM were detected even in far-field plume samples. Within the Von Damm hydrothermal plume, we have used our data to hypothesize a microbial food web in which chemoautotrophy supports a heterotrophic community of microorganisms. Such an active microbial food web would provide a source of labile organic carbon to the deep ocean that should be considered in any future studies evaluating sources and sinks of carbon from hydrothermal venting to the deep ocean.

  19. Oxygen isotope exchange kinetics of mineral pairs in closed and open systems: Applications to problems of hydrothermal alteration of igneous rocks and Precambrian iron formations

    Science.gov (United States)

    Gregory, R.T.; Criss, R.E.; Taylor, H.P.

    1989-01-01

    The systematics of stable-isotope exchange between minerals and fluids are examined in the context of modal mineralogical variations and mass-balance considerations, both in closed and in open systems. On mineral-pair ??18O plots, samples from terranes that have exchanged with large amounts of fluid typically map out steep positively-sloped non-equilibrium arrays. Analytical models are derived to explain these effects; these models allow for different exchange rates between the various minerals and the external fluids, as well as different fluid fluxes. The steep arrays are adequately modelled by calculated isochron lines that involve the whole family of possible exchange trajectories. These isochrons have initially-steep near-vertical positive slopes that rotate toward a 45?? equilibrium slope as the exchange process proceeds to completion. The actual data-point array is thus analogous to the hand of an "isotopic clock" that measures the duration of the hydrothermal episode. The dimensionless ratio of the volumetric fluid flux to the kinetic rate parameter ( u k) determines the shape of each individual exchange trajectory. In a fluid-buffered system ( u k ??? 1), the solutions to the equations: (1) are independent of the mole fractions of the solid phases; (2) correspond to Taylor's open-system water/rock equation; and (3) yield straight-line isochrons that have slopes that approach 1 f, where f is the fraction reacted of the more sluggishly exchanging mineral. The isochrons for this simple exchange model are closely congruent with the isochrons calculated for all of the more complex models, thereby simplifying the application of theory to actual hydrothermal systems in nature. In all of the models an order of magnitude of time (in units of kt) separates steep non-equilibrium arrays (e.g., slope ??? 10) from arrays approaching an equilibrium slope of unity on a ??-?? diagram. Because we know the approximate lifetimes of many hydrothermal systems from geologic and

  20. Suboxic deep seawater in the late Paleoproterozoic: Evidence from hematitic chert and iron formation related to seafloor-hydrothermal sulfide deposits, central Arizona, USA

    Science.gov (United States)

    Slack, J.F.; Grenne, Tor; Bekker, A.; Rouxel, O.J.; Lindberg, P.A.

    2007-01-01

    A current model for the evolution of Proterozoic deep seawater composition involves a change from anoxic sulfide-free to sulfidic conditions 1.8??Ga. In an earlier model the deep ocean became oxic at that time. Both models are based on the secular distribution of banded iron formation (BIF) in shallow marine sequences. We here present a new model based on rare earth elements, especially redox-sensitive Ce, in hydrothermal silica-iron oxide sediments from deeper-water, open-marine settings related to volcanogenic massive sulfide (VMS) deposits. In contrast to Archean, Paleozoic, and modern hydrothermal iron oxide sediments, 1.74 to 1.71??Ga hematitic chert (jasper) and iron formation in central Arizona, USA, show moderate positive to small negative Ce anomalies, suggesting that the redox state of the deep ocean then was at a transitional, suboxic state with low concentrations of dissolved O2 but no H2S. The presence of jasper and/or iron formation related to VMS deposits in other volcanosedimentary sequences ca. 1.79-1.69??Ga, 1.40??Ga, and 1.24??Ga also reflects oxygenated and not sulfidic deep ocean waters during these time periods. Suboxic conditions in the deep ocean are consistent with the lack of shallow-marine BIF ??? 1.8 to 0.8??Ga, and likely limited nutrient concentrations in seawater and, consequently, may have constrained biological evolution. ?? 2006 Elsevier B.V. All rights reserved.

  1. Experimental hydrothermal alteration of andesite at 325 ˚C, 300 bar: Comparison with the hydrothermal fluids in the Hatoma Knoll, southern Okinawa Trough

    Science.gov (United States)

    Saitoh, Masafumi; Shibuya, Takazo; Nozaki, Tatsuo; Torimoto, Junji; Ueda, Hisahiro; Sato, Tomoki; Suzuki, Katsuhiko

    2017-04-01

    Formation processes and types of hydrothermal sulfide deposits are closely related to chemical compositions of subseafloor hydrothermal fluids. Subseafloor hydrothermal alteration of intermediate to felsic rocks is a major process that controls the fluid compositions in the arc/back-arc hydrothermal systems, although the chemical reaction process during water-rock interaction has not been examined in detail. We experimentally reacted a NaCl solution under high-pressure and -temperature conditions with fresh andesite collected from the Hatoma Knoll, southern Okinawa Trough. The concentrations of selected elements (e.g., K, Ca, and Si) in the fluid obtained by the experiment are inconsistent with those of the hydrothermal fluids in the Hatoma Knoll. The present results suggest that the inputs of magmatic volatiles derived from andesitic magma to the hydrothermal fluids may not be significant whereas hydrothermal reactions with felsic rocks (e.g., dacite and rhyolite) and/or sediments may contribute substantially to the fluid compositions in the Hatoma Knoll.

  2. Geochemical variability of hydrothermal emissions between three Pacific volcanic arc systems: Alaskan-Aleutian and Cascadian, North America and Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Blackstock, J. M.; Horton, T. W.; Gravley, D. M.; Deering, C. D.

    2013-12-01

    Knowledge of the source, transport, and fate of hydrothermal fluids in the upper crust informs our understanding and interpretation of ore-forming processes, volcanogenic hazards, geothermal resources, and volatile cycling. Co-variation between fluid inclusion CO2/CH4 and N2/Ar ratios is an established tracer of magmatic, meteoric, and crustal fluid end-members. Yet, this tracer has had limited application to macroscopic fluid reservoirs accessible via geothermal wells and hydrothermal features (e.g. pools). In this study, we compared the covariance CO2/CH4 and N2/Ar ratios of gases collected throughout the Taupo Volcanic Zone, New Zealand (TVZ), the Alaska-Aleutian Volcanic Arc, USA (AAVA), and the Cascadian Volcanic Arc, USA (CVA) with corresponding δ13C and 3He/4He values. Our findings show that there is good agreement between these proxies for different end-member contributions at coarse scales. However, some samples classified as meteoric water according to the CO2/CH4 and N2/Ar ratios also show more positive δ13C values (~ -7.0 per mil) and relatively higher 3He/4He ratios indicative of magmatic input from primarily mantle sources. This unexpected result may be related to magmatic fluids, CO2 in particular, mixing with predominantly meteoric derived waters. The potential to identify magmatic CO2 in groundwater samples overlying geothermal systems in differing volcanic arc settings using simple and cost-effective gas ratios is a promising step forward in the search for ';surface blind' but developable geothermal systems and volcanic monitoring. 3He/4He anomalies also support this inference and underscore the potential decoupling of thermal anomalies and magmatic-derived fluids in the Earth's crust. The general agreement between the co-variation of CO2/CH4 and N2/Ar ratios with other isotope and geochemical proxies for magmatic, meteoric, and crustal end-members is encouraging to employ expanded use of these ratios for both the exploration and monitoring of

  3. Gamma ray spectrometry for recognition of hydrothermal alteration zones related to a low sulfidation epithermal gold mineralization (eastern Pontides, NE Türkiye)

    Science.gov (United States)

    Maden, Nafiz; Akaryalı, Enver

    2015-11-01

    This study presents an interpretation of radiospectrometric and magnetic data of Arzular mineralization site, which is one of the best examples for epithermal gold deposits located in the southern zone of the Eastern Pontides (NE Türkiye). Potassium is generally the most useful pathfinder element for gold mineralization zones because of its high level in altered rock surrounding the deposits. Where gold is hosted within quartz veins, typically the vein is low in the radioelements, but the hydrothermally altered host rocks will usually have a distinct radioelement signature useful for exploration. In this study, magnetic, susceptibility and radiospectrometric survey data radiometric signatures associated with the host rocks favorable for the mineralization, enhancing techniques such as the ratio maps as well as potassium (%K), equivalent thorium (eTh ppm) and equivalent uranium (eU ppm) maps were utilized. Our analysis showed that the gold mineralization associated with the alteration is significantly related to increase in potassium, due to adularia, a low T K-feldspar, and decreases in uranium and thorium due to the hydrothermal alteration and magmatic intrusion processes during the regional tectonic activities.

  4. Microbial bio-mineralization processes in hydrothermal travertine: the case study of two active travertine systems (Tuscany, Italy).

    Science.gov (United States)

    Barilaro, Federica; Bontognali, Tomaso R. R.; Mc Kenzie, Judith A.; Vasconcelos, Crisogono

    2015-04-01

    ). The nano-globules, that represent the first stage of precipitation, coalesce and organize in rods. The assemblage of these rods gives rise to triangular-like morphologies that, gradually, evolve to form well developed calcite crystals, substituting/replacing the organic matter. The presence of EPS, microbs, and calcite mineral phase suggest that biological activity and degradation of organic matter may play a fundamental role in the travertine formation. Acicular crystals of aragonite, nucleated also on organic compound and characterized by the lack of nano-globules, surround the calcite crystals aggregates. The precipitation of aragonite may suggest a change in micro-environmental conditions that involve a predominantly abiotic mechanism of precipitation. Gypsum crystals were mainly individuated in the upper zone of microbial mats and filamentous organic structures connected to the crystals have been observed. A biologically induced process is also claimed for the identified framboidal pyrite related to possible sulphate reducing bacteria. These observations suggest that biological activities are crucial in travertine precipitation. Travertine precipitation is not only related to abiotic parameters of calcium equilibrium, such us physicochemical carbon dioxid degassing and elevated temperature of the hydrothermal water. This study 1) demonstrates that organomineralization processes are not only exclusive of marine carbonate and tufa and 2) confirms the importance of micro- and nano-scale investigation to discriminate between biotic versus abiotic origin of the precipitates.

  5. Geostructural context of a hydrothermal system by geophysical methods: Case of Hammam Righa, Algeria

    Science.gov (United States)

    Hocine, Amina; Abtout, Abdesalam; Hamai, Lamine

    2017-04-01

    The presence of thermal water depends on the stratigraphic and structural conditions of the site. Indeed, hydrodynamism is directly related to the geostructural elements. In northern Algeria, thermal springs are increasing from west to east. They are mainly situated along the Tellian Atlas which has a complex geology. In this study, we are interested in the thermal site of Hammam Righa, located about 100 km west of Algiers, southwest of the neogene Basin of Mitidja (northern Algeria). This region, very rugged and subject to a developed tectonic rupture, has been discovered and exploited since roman times. The existing drilling on the site cross a superior cover of travertines and marly clay layers of Miocene and Cretaceous. Thermal waters emerge in a more or less impermeable outcrop of limestone marls of the Upper Cretaceous with elevated temperatures (44-68 °C). In order to define the structure and the nature of the top of the aquifer and to determine the faults system inducing the emergence of thermal waters, a hydrogeophysical survey by electrical prospection was undertaken in this region. The electrical soundings (VES, AB = 1000m) realized according to 10 profiles of direction E-W cover an area of 2.5 Km2. Interpretation of these VES resulted in geo-electric sections and iso-resistivity maps, to finally map the top of the Upper Cretaceous. The preliminary results of this study allowed to clarify the lithological nature of the top of the Upper Cretaceous and to demonstrate that there is a variation of depth according to the system of faults highlighted.

  6. Vent fluid chemistry in Bahía Concepción coastal submarine hydrothermal system, Baja California Sur, Mexico

    Science.gov (United States)

    Prol-Ledesma, R. M.; Canet, C.; Torres-Vera, M. A.; Forrest, M. J.; Armienta, M. A.

    2004-10-01

    Shallow submarine hydrothermal activity has been observed in the Bahía Concepción bay, located at the Gulf coast of the Baja California Peninsula, along faults probably related to the extensional tectonics of the Gulf of California region. Diffuse and focused venting of hydrothermal water and gas occurs in the intertidal and shallow subtidal areas down to 15 m along a NW-SE-trending onshore-offshore fault. Temperatures in the fluid discharge area vary from 50 °C at the sea bottom up to 87 °C at a depth of 10 cm in the sediments. Chemical analyses revealed that thermal water is enriched in Ca, As, Hg, Mn, Ba, HCO 3, Li, Sr, B, I, Cs, Fe and Si, and it has lower concentrations of Cl, Na, SO 4 and Br than seawater. The chemical characteristics of the water samples indicate the occurrence of mixing between seawater and a thermal end-member. Stable isotopic oxygen and hydrogen composition of thermal samples plot close to the Local Meteoric Water Line on a mixing trend between a thermal end-member and seawater. The composition of the thermal end-member was calculated from the chemistry of the submarine samples data by assuming a negligible amount of Mg for the thermal end-member. The results of the mixing model based on the chemical and isotopic composition indicate a maximum of 40% of the thermal end-member in the submarine vent fluid. Chemical geothermometers (Na/Li, Na-K-Ca and Si) were applied to the thermal end-member concentration and indicate a reservoir temperature of approximately 200 °C. The application of K-Mg and Na/Li geothermometers for vent fluids points to a shallow equilibrium temperature of about 120 °C. Results were integrated in a hydrogeological conceptual model that describes formation of thermal fluids by infiltration and subsequent heating of meteoric water. Vent fluid is generated by further mixing with seawater.

  7. Hydrothermal growth and characterization of vertically well-aligned and dense ZnO nanorods on glass and silicon using a simple optimizer system

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad, Sabah M., E-mail: Sabahaskari14@gmail.com; Ahmed, Naser M.; Abd-Alghafour, Nabeel M. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia); Hassan, Z., E-mail: zai@usm.my [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia); CRI Natural Sciences, Universiti Sains Malaysia, Penang 11800 (Malaysia); Talib, Rawnaq A. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia); Polymer Research Center, University of Basra (Iraq); Omar, A. F. [School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia)

    2016-07-06

    Vertically, well-aligned and high density ZnO nanorods were successfully hydrothermally grown on glass and silicon substrates using a simple and low cost system. The mechanism of synthesis of ZnO nanorods, generated with our system under hydrothermal conditions, is investigated in this report. Field-emission scanning electron microscopy indicated that the fabricated ZnO nanorods on both substrates have hexagonal shape with diameters ranging from 20 nm to 70 nm which grew vertically from the substrate. XRD analysis confirms the formation of wurtzite ZnO phase with a preferred orientation along (002) direction perpendicular on the substrate and enhanced crystallinity. The low value of the tensile strain (0.126 %) revealed that ZnO nanorods preferred to grow along the c-axis for both substrates. Photoluminescence spectra exhibited a strong, sharp UV near band edge emission peak with narrow FWHM values for both samples.

  8. A model for the magmatic-hydrothermal system at Mount Rainier, Washington, from seismic and geochemical observations

    Science.gov (United States)

    Moran, S. C.; Zimbelman, D. R.; Malone, S. D.

    Mount Rainier is one of the most seismically active volcanoes in the Cascade Range, with an average of one to two high-frequency volcano-tectonic (or VT) earthquakes occurring directly beneath the summit in a given month. Despite this level of seismicity, little is known about its cause. The VT earthquakes occur at a steady rate in several clusters below the inferred base of the Quaternary volcanic edifice. More than half of 18 focal mechanisms determined for these events are normal, and most stress axes deviate significantly from the regional stress field. We argue that these characteristics are most consistent with earthquakes in response to processes associated with circulation of fluids and magmatic gases within and below the base of the edifice.Circulation of these fluids and gases has weakened rock and reduced effective stress to the point that gravity-induced brittle fracture, due to the weight of the overlying edifice, can occur. Results from seismic tomography and rock, water, and gas geochemistry studies support this interpretation. We combine constraints from these studies into a model for the magmatic system that includes a large volume of hot rock (temperatures greater than the brittle-ductile transition) with small pockets of melt and/or hot fluids at depths of 8-18km below the summit. We infer that fluids and heat from this volume reach the edifice via a narrow conduit, resulting in fumarolic activity at the summit, hydrothermal alteration of the edifice, and seismicity.

  9. Quantitative impact of hydrothermal alteration on electrical resistivity in geothermal systems from a joint analysis of laboratory measurements and borehole data in Krafla area, N-E Iceland

    Science.gov (United States)

    Lévy, Léa; Páll Hersir, Gylfi; Flóvenz, Ólafur; Gibert, Benoit; Pézard, Philippe; Sigmundsson, Freysteinn; Briole, Pierre

    2016-04-01

    Rock permeability and fluid temperature are the two most decisive factors for a successful geothermal drilling. While those parameters are only measured from drilling, they might be estimated on the basis of their impact on electrical resistivity that might be imaged from surface soundings, for example through TEM (Transient Electro Magnetic) down to one km depth. The electrical conductivity of reservoir rocks is the sum of a volume term depending on fluid parameters and a surface term related to rock alteration. Understanding the link between electrical resistivity and geothermal key parameters requires the knowledge of hydrothermal alteration and its petrophysical signature with the Cation Exchange Capacity (CEC). Fluid-rock interactions related to hydrothermal circulation trigger the precipitation of alteration minerals, which are both witnesses of the temperature at the time of reaction and new paths for the electrical current. Alteration minerals include zeolites, smectites, chlorites, epidotes and amphiboles among which low temperatures parageneses are often the most conductive. The CEC of these mineral phases contributes to account for surface conductivity occuring at the water-rock interface. In cooling geothermal systems, these minerals constitute in petrophysical terms and from surface electrical conduction a memory of the equilibrium phase revealed from electrical probing at all scales. The qualitative impact of alteration minerals on resistivity structure has been studied over the years in the Icelandic geothermal context. In this work, the CEC impact on pore surfaces electrical conductivity is studied quantitatively at the borehole scale, where several types of volcanic rocks are mixed together, with various degrees of alteration and porosity. Five boreholes located within a few km at the Krafla volcano, Northeast Iceland, constitute the basis for this study. The deepest and reference hole, KJ-18, provides cuttings of rock and logging data down to 2215

  10. Thickness distributions and evolution of growth mechanisms of NH4-illite from the fossil hydrothermal system of Harghita Bai, Eastern Carpathians, Romania

    Science.gov (United States)

    Bobos, Iuliu; Eberl, D.D.

    2013-01-01

    The crystal growth of NH4-illite (NH4-I) from the hydrothermal system of Harghita Bãi (Eastern Carpathians) was deduced from the shapes of crystal thickness distributions (CTDs). The 4-illite-smectite (I-S) interstratified structures (R1, R2, and R3-type ordering) with a variable smectite-layer content. The NH4-I-S (40–5% S) structures were identified underground in a hydrothermal breccia structure, whereas the K-I/NH4-I mixtures were found at the deepest level sampled (−110 m). The percentage of smectite interlayers generally decreases with increasing depth in the deposit. This decrease in smectite content is related to the increase in degree of fracturing in the breccia structure and corresponds to a general increase in mean illite crystal thickness. In order to determine the thickness distributions of NH4-I crystals (fundamental illite particles) which make up the NH4-I-S interstratified structures and the NH4,-I/K-I mixtures, 27 samples were saturated with Li+ and aqueous solutions of PVP-10 to remove swelling and then were analyzed by X-ray diffraction. The profiles for the mean crystallite thickness (Tmean) and crystallite thickness distribution (CTD) of NH4-I crystallites were determined by the Bertaut-Warren-Averbach method using the MudMaster computer code. The Tmean of NH4-I from NH4-I-S samples ranges from 3.4 to 7.8 nm. The Tmean measured for the NH4-I/K-I mixture phase ranges from 7.8 nm to 11.7 nm (NH4-I) and from 12.1 to 24.7 nm (K-I). The CTD shapes of NH4-I fundamental particles are asymptotic and lognormal, whereas illites from NH4-I/K-I mixtures have bimodal shapes related to the presence of two lognormal-like CTDs corresponding to NH4-I and K-I. The crystal-growth mechanism for NH4-I samples was simulated using the Galoper code. Reaction pathways for NH4-I crystal nucleation and growth could be determined for each sample by plotting their CTD parameters on an α–β2 diagram constructed using Galoper. This analysis shows that NH4-I

  11. Novel Barite Chimneys at the Loki's Castle Vent Field Shed Light on Key Factors Shaping Microbial Communities and Functions in Hydrothermal Systems.

    Science.gov (United States)

    Steen, Ida H; Dahle, Håkon; Stokke, Runar; Roalkvam, Irene; Daae, Frida-Lise; Rapp, Hans Tore; Pedersen, Rolf B; Thorseth, Ingunn H

    2015-01-01

    . This may be related to niche-specific physical characteristics. Altogether, the model provides a reference for future studies and illustrates the importance of systematic comparative studies of spatially closely connected niches in order to fully understand the geomicrobiology of hydrothermal systems.

  12. Novel barite chimneys at the Loki´s Castle Vent Field shed light on key factors shaping microbial communities and functions in hydrothermal systems

    Directory of Open Access Journals (Sweden)

    Ida Helene eSteen

    2016-01-01

    a vent field. This may be related to niche-specific physical characteristics. Altogether, the model provides a reference for future studies and illustrates the importance of systematic comparative studies of spatially closely connected niches in order to fully understand the geobiology of hydrothermal systems.

  13. Double, double, (but mostly) toil, and trouble: A multidisciplinary approach to quantify the permeability of an active volcanic hydrothermal system (Whakaari volcano, New Zealand)

    Science.gov (United States)

    Heap, Michael; Kennedy, Ben; Farquharson, Jamie; Ashworth, James; Mayer, Klaus; Letham-Brake, Mark; Reuschlé, Thierry; Gilg, Albert; Scheu, Betty; Lavallée, Yan; Siratovich, Paul; Cole, Jim; Jolly, Art; Dingwell, Donald

    2016-04-01

    Our multidisciplinary approach, which combines field techniques and traditional laboratory methods, aims to better understand the permeability of an active volcanic hydrothermal system, a vital prerequisite for understanding and modelling the behaviour of hydrothermal systems worldwide. Whakaari volcano (an active stratovolcano located 48 km off New Zealand's North Island) hosts an open, highly reactive hydrothermal system (hot springs and mud pools, fumaroles, acid streams and lakes) and represents an ideal natural laboratory to undertake such a study. We first gained an appreciation of the different lithologies at Whakaari and (where possible) their lateral and vertical extent through reconnaissance by land, sea, and air. Due to the variable nature of these altered lithologies (mainly lavas and tuffs), we measured porosity-permeability for in excess of a hundred rock hand samples using field techniques. We also measured the permeability of recent, unconsolidated deposits using a field soil permeameter. Our field measurements were then groundtruthed on a subset of these samples (~40-50) using traditional laboratory techniques: helium pycnometry and measurements of permeability using a benchtop permeameter, including measurements under increasing confining pressure (i.e., depth). In all, our measurements highlight that the porosity of the materials at Whakaari can vary from ~0.01 to ~0.6, and permeability can vary by eight orders of magnitude. However, our data show no discernable trend between porosity and permeability. A combination of macroscopic and microscopic observations, chemistry (XRF), mineralogy (XRD), and mercury porosimetry highlight that the absence of a robust porosity-permeability relationship is the product of an insane variability in alteration and microstructure (pore size, particle size, pore connectivity, presence/absence of microcracks, layering, amongst others). While our systematic study offers the most complete porosity-permeability dataset

  14. Hydrothermal speleogenesis in carbonates and metasomatic silicites induced by subvolcanic intrusions: a case study from the Štiavnické vrchy Mountains, Slovakia

    Directory of Open Access Journals (Sweden)

    Pavel Bella

    2016-01-01

    Full Text Available Several caves of hydrothermal origin in crystalline limestones and metasomatic silicites were investigated in the central zone of the Štiavnica stratovolcano, Štiavnické vrchy Mountains, central Slovakia. Evidence of hydrothermal origin includes irregular spherical cave morphology sculptured by ascending thermal water, occurrence of large calcite crystals and hydrothermal alteration of host rocks, including hydrothermal clays. The early phases of speleogenesis in the crystalline limestone near Sklené Teplice Spa were caused by post-magmatic dissolution linked either to the emplacement of subvolcanic granodiorite intrusions during Late Badenian time or to the spatially associated Late Sarmatian epithermal system. Speleogenesis in metasomatic silicites in the Šobov area is related to hydrothermal processes associated with the pre-caldera stage of the Štiavnica stratovolcano in Late Badenian. Both localities are remarkable examples of hydrothermal speleogenesis associated with Miocene volcanic and magmatic activity in the Western Carpathians.

  15. Geological Fluid Mapping in the Tongling Area: Implications for the Paleozoic Submarine Hydrothermal System in the Middle-Lower Yangtze Metallogenic Belt, East China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Tongling area is one of the 7 ore-cluster areas in the Middle-Lower Yangtze metallogenic belt, East China, and has tectonically undergone a long-term geologic history from the late Paleozoic continental rifting, through the Middle Triassic continent-continent collision to the Jurassic-Cretaceous intracontinental tectono-magmatic activation. The Carboniferous sedimentary-exhalative processes in the area produced widespread massive sulfides with ages of 303-321 Ma, which partly formed massive pyrite-Cu deposits, but mostly provided significant sulfur and metals to the skarn Cu mineralization associated with the Yanshanian felsic intrusions.To understand the Carboniferous submarine hydrothermal system, an area of about 1046 km2 was chosen to carry out the geological fluid mapping. Associated with massive sulfide formation, footwall sequences 948 m to 1146 m thick, composed of the Lower Silurian-Upper Devonian sandstone, siltstone and thin-layered shale, were widely altered. This hydrothermal alteration is interpreted to reflect largescale hydrothermal fluid flow associated with the late Paleozoic crustal rifting and subsidence. Three hydrothermal alteration types, i.e., deep-level semiconformable silicification (S1), fracture-controlled quartz-sericite-pyrite alteration (S2-3), and upper-level sub-discordant quartz-sericite-chlorite alteration (D3), were developed to form distinct zones in the mapped area. About 50-m thick semiconformable siliclfication zones are located at ~1-km depth below massive sulfides and developed between an impermeable shale caprock (S1) and the underlying Ordovician unaltered limestone.Comparisons with modern geothermal systems suggest that the alteration zones record a sub-seafloor aquifer with the most productive hydrothermal fluid flow. Fracture-controlled quartz-sericite-pyrite alteration formed transgressive zones, which downward crosscut the semiconformable alteration zones,and upwards grade into sub-discordant alteration zones

  16. Modelling of Thermal Advective Reactive Flow in Hydrothermal Mineral Systems Using an Implicit Time-stepped Finite Element Method.

    Science.gov (United States)

    Hornby, P. G.

    2005-12-01

    Understanding chemical and thermal processes taking place in hydrothermal mineral deposition systems could well be a key to unlocking new mineral reserves through improved targeting of exploration efforts. To aid in this understanding it is very helpful to be able to model such processes with sufficient fidelity to test process hypotheses. To gain understanding, it is often sufficient to obtain semi-quantitative results that model the broad aspects of the complex set of thermal and chemical effects taking place in hydrothermal systems. For example, it is often sufficient to gain an understanding of where thermal, geometric and chemical factors converge to precipitate gold (say) without being perfectly precise about how much gold is precipitated. The traditional approach is to use incompressible Darcy flow together with the Boussinesq approximation. From the flow field, the heat equation is used to advect-conduct the heat. The flow field is also used to transport solutes by solving an advection-dispersion-diffusion equation. The reactions in the fluid and between fluid and rock act as source terms for these advection-dispersion equations. Many existing modelling systems that are used for simulating such systems use explicit time marching schemes and finite differences. The disadvantage of this approach is the need to work on rectilinear grids and the number of time steps required by the Courant condition in the solute transport step. The second factor can be particularly significant if the chemical system is complex, requiring (at a minimum) an equilibrium calculation at each grid point at each time step. In the approach we describe, we use finite elements rather than finite differences, and the pressure, heat and advection-dispersion equations are solved implicitly. The general idea is to put unconditional numerical stability of the time integration first, and let accuracy assume a secondary role. It is in this sense that the method is semi-quantiative. However

  17. The mineralogical characteristics of the hydrothermal types alteration from Nistru ore deposit, Baia Mare metallogenetic district

    Directory of Open Access Journals (Sweden)

    Floarea Damian

    2003-04-01

    Full Text Available The hydrothermal alteration types, which have affected intrusive and volcanic rocks from Nistru ore deposit, are related to fluids composition varied in their evolution within hydrothermal systems. The early stage of the hydrothermal activity has produced extensive propylitisation and potassic alteration (orthoclase, biotite, sericite associated with the central part of the quartz-micromonzodioritic porphyry stock. The late stage of the fluids differentiation is determined by the hydrogen-ion metasomatism (phyllic alteration, argillic alteration, characterized by a large vertical variation. The hydrogen-ion metasomatism is associated with the bor metasomatism, generated by acid solutions and at a high temperature. The vertical and lateral zoning character of the hydrothermal alterations is related to differences in rock composition and variation in physical-chemical conditions during the periods of subvolcanic intrusion and mineralization.

  18. Methane gas sensing at relatively low operating temperature by hydrothermally prepared SnO{sub 2} nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Amutha, A. [Pondicherry University, Centre for Nanoscience and Technology (India); Amirthapandian, S. [Indira Gandhi Centre for Atomic Research, Materials Physics Division, Materials Science Group (India); Prasad, A. K. [Indira Gandhi Centre for Atomic Research, Surface and Nanoscience Division, Materials Science Group (India); Panigrahi, B. K. [Indira Gandhi Centre for Atomic Research, Materials Physics Division, Materials Science Group (India); Thangadurai, P., E-mail: thangadurai.p@gmail.com [Pondicherry University, Centre for Nanoscience and Technology (India)

    2015-07-15

    Tin oxide (SnO{sub 2}) nanorods were prepared by surfactant-free hydrothermal method and their methane gas sensing characteristics were studied. These SnO{sub 2} nanorods were characterized by XRD, SEM, TEM, EDS, EELS, UV–Visible, and Raman spectroscopies. The SnO{sub 2} nanorods were single crystalline possessing tetragonal rutile structure. Average diameter of the nanorods was in the range from 8 to 48 nm with an average length of 174 nm. The diameter of the nanorod was found to increase with the increase of reaction time. The E{sub g} and A{sub 1g} Raman modes showed a significant blue and red shift, respectively, and this was due to the contribution from the phonons with q ≠ 0 in the first Brillouin zone. Gas sensing measurements against methane gas showed a good sensitivity at an operating temperature of 100 °C, and the maximum gas sensitivity was observed at 175 °C. Our present experiments clearly demonstrate the sensitivity of methane up to 300 ppm at 100 °C, which is a lower operating temperature compared to the previously reported values. Hydrogen sensor was also fabricated with the same SnO{sub 2} nanorods and its performance was compared with the methane gas sensor. These rods show better sensitivity toward methane gas than hydrogen gas.

  19. Tracing thermal aquifers of El Chichón volcano-hydrothermal system (México) with 87Sr/ 86Sr, Ca/Sr and REE

    Science.gov (United States)

    Peiffer, L.; Taran, Y. A.; Lounejeva, E.; Solís-Pichardo, G.; Rouwet, D.; Bernard-Romero, R. A.

    2011-08-01

    The volcano-hydrothermal system of El Chichón volcano, Chiapas, Mexico, is characterized by numerous thermal manifestations including an acid lake, steam vents and boiling springs in the crater and acid and neutral hot springs and steaming ground on the flanks. Previous research on major element chemistry reveals that thermal waters of El Chichón can be divided in two groups: (1) neutral waters discharging in the crater and southern slopes of the volcano with chloride content ranging from 1500 to 2200 mg/l and (2) acid-to-neutral waters with Cl up to 12,000 mg/l discharging at the western slopes. Our work supports the concept that each group of waters is derived from a separate aquifer (Aq. 1 and Aq. 2). In this study we apply Sr isotopes, Ca/Sr ratios and REE abundances along with the major and trace element water chemistry in order to discriminate and characterize these two aquifers. Waters derived from Aq. 1 are characterized by 87Sr/ 86Sr ratios ranging from 0.70407 to 0.70419, while Sr concentrations range from 0.1 to 4 mg/l and Ca/Sr weight ratios from 90 to 180, close to average values for the erupted rocks. Waters derived from Aq. 2 have 87Sr/ 86Sr between 0.70531 and 0.70542, high Sr concentrations up to 80 mg/l, and Ca/Sr ratio of 17-28. Aquifer 1 is most probably shallow, composed of volcanic rocks and situated beneath the crater, within the volcano edifice. Aquifer 2 may be situated at greater depth in sedimentary rocks and by some way connected to the regional oil-gas field brines. The relative water output (l/s) from both aquifers can be estimated as Aq. 1/Aq. 2-30. Both aquifers are not distinguishable by their REE patterns. The total concentration of REE, however, strongly depends on the acidity. All neutral waters including high-salinity waters from Aq. 2 have very low total REE concentrations (hydrothermal vapors, REE distribution in thermal waters reflects the dissolution of volcanic rocks close to the surface or lake sediments as is the case

  20. Dynamics of hydrothermal seeps from the Salton Sea geothermal system (California, USA) constrained by temperature monitoring and time series analysis

    Science.gov (United States)

    Svensen, Henrik; Hammer, Ã.˜Yvind; Mazzini, Adriano; Onderdonk, Nathan; Polteau, Stephane; Planke, Sverre; Podladchikov, Yuri Y.

    2009-09-01

    Water-, mud-, gas-, and petroleum-bearing seeps are part of the Salton Sea geothermal system (SSGS) in southern California. Carbon dioxide is the main component behind the seeps in the Davis-Schrimpf seep field (˜20,000 m2). In order to understand the mechanisms driving the system, we have investigated the seep dynamics of the field by monitoring the temperature of two pools and two gryphons for 2180 h (90.8 days) in the period from December 2006 to March 2007, with a total of 32,700 measurements per station. The time series have been analyzed by statistical methods using cross correlation, autocorrelation and spectral analysis, and autoregressive modeling. The water-rich pools never exceed 34.0°C and are characterized by low-amplitude temperature variations controlled by the diurnal cycles in air temperature. The long-term validity of these results is evident from a second period of temperature monitoring of one of the pools from December 2007 to April 2008 (120 days). In contrast to the pools, the mud-rich gryphons have a strikingly different behavior. The gryphons are hotter (maximum 69.7°C) and have large amplitude variations (standard deviation of 6.4) that overprint any signal from external diurnal forcing. Autoregressive modeling shows the presence of distinct hot and cold pulses in the gryphon temperature time series, with amplitudes up to 3°C. These pulses likely reflect a combination of hydrothermal flux variations from the SSGS and the local temporal changes in bubbling activity within the gryphons.

  1. Metal flux from hydrothermal vents increased by organic complexation

    Science.gov (United States)

    Sander, Sylvia G.; Koschinsky, Andrea

    2011-03-01

    Hydrothermal vents in the sea floor release large volumes of hot, metal-rich fluids into the deep ocean. Until recently, it was assumed that most of the metal released was incorporated into sulphide or oxide minerals, and that the net flux of most hydrothermally derived metals to the open ocean was negligible. However, mounting evidence suggests that organic compounds bind to and stabilize metals in hydrothermal fluids, increasing trace-metal flux to the global ocean. In situ measurements reveal that hydrothermally derived chromium, copper and iron bind to organic molecules on mixing with sea water. Geochemical model simulations based on data from two hydrothermal vent sites suggest that complexation significantly increases metal flux from hydrothermal systems. According to these simulations, hydrothermal fluids could account for 9% and 14% of the deep-ocean dissolved iron and copper budgets respectively. A similar role for organic complexation can be inferred for the hydrothermal fluxes of other metals, such as manganese and zinc.

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

    Science.gov (United States)

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

    2014-05-01

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

  3. New boron isotopic evidence for sedimentary and magmatic fluid influence in the shallow hydrothermal vent system of Milos Island (Aegean Sea, Greece)

    Science.gov (United States)

    Wu, Shein-Fu; You, Chen-Feng; Lin, Yen-Po; Valsami-Jones, Eugenia; Baltatzis, Emmanuel

    2016-01-01

    Magmatic sources may contribute a significant amount of volatiles in geothermal springs; however, their role is poorly understood in submarine hydrothermal systems worldwide. In this study, new results of B and δ11B in 41 hydrothermal vent waters collected from the shallow hydrothermal system of Milos island in the Aegean Sea were combined with previously published data from other tectonic settings and laboratory experiments to quantify the effects of phase separation, fluid/sediment interaction and magmatic contribution. Two Cl-extreme solutions were identified, high-Cl waters (Cl as high as 2000 mM) and low-Cl waters (Cl < 80 mM). Both sets of waters were characterized by high B/Cl (~ 1.2-5.3 × 10- 3 mol/mol) and extremely low δ11B (1.4-6.3‰), except for the waters with Mg content of near the seawater value and δ11B = 10.3-17.4‰. These high-Cl waters with high B/Cl and low δ11B plot close to the vent waters in sediment-hosted hydrothermal system (i.e., Okinawa Trough) or fumarole condensates from on-land volcanoes, implying B addition from sediment or magmatic fluids plays an important role. This is in agreement with fluid/sediment interactions resulting in the observed B and δ11B, as well as previously reported Br/I/Cl ratios, supporting a scenario of slab-derived fluid addition with elevated B, 11B-rich, and low Br/Cl and I/Cl, which is derived from the dehydration of subducted-sediments. The slab fluid becomes subsequently mixed with the parent magma of Milos. The deep brine reservoir is partially affected by injections of magmatic fluid/gases during degassing. The results presented here are crucial for deciphering the evolution of the brine reservoirs involved in phase separation, fluid/sediment interaction and magmatic contribution in the deep reaction zone of the Milos hydrothermal system; they also have implications in the understanding of the formation of metallic vein mineralization.

  4. Model for the heat source of the Cerro Prieto magma-hydrothermal system, Baja California, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.; Cox, B.

    1981-01-01

    Earlier studies at Cerro Prieto led to the development of a qualitative model for fluid flow in the geothermal system before it was drilled and perturbed by production. Current efforts are directed towards numerical modeling of heat and mass transfer in the system in this undisturbed state. This one-dimensional model assumes that the heat source was a single basalt/gabbro intrusion which provided heat to the system as it cooled. After compilation of various information of the physical properties of the reservoir, the enthalpy contained in two 1 cm thick sections across the reservoir orthogonal to each other was calculated. Various shapes, sizes and depths for the intrusion were considered as initial conditions and boundary conditions for the calculations of heat transfer. A family of numerical models which so far gives the best matches to the conditions observed in the field today have in common a funnel-shaped intrusion with a top 4 km wide emplaced at a depth of 5 km some 30,000 to 50,000 years ago, providing heat to the geothermal system.

  5. Model of the heat source of the Cerro Prieto magma-hydrothermal system, Baja California, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.; Cox, B.

    1982-08-10

    Earlier studies at Cerro Prieto by UCR have led to the development of a qualitative model for field flow in the geothermal system before it was drilled and perturbed by production. Current efforts are directed towards numerical modelling of heat and mass transfer in the system in this undisturbed state. A two-dimensional model assumes that the heat sources were a single basalt/gabbro intrusion which provided heat to the system as it cooled. After compiling various information on the physical properties of the reservoir, the enthalpy contained in two 1cm thick section across the reservoir orthogonal to each other was calculated. Next various shapes, sizes and depths for the intrusion as initial conditions and boundary conditions for the calculation of heat transfer were considered. A family of numerical models which so far gives the best matches to the conditions observed in the field today have in common a funnel-shaped intrusion with a top 4km wide emplaced at a depth of 5km some 30,000 to 50,000 years ago, providing heat to the geothermal system. Numerical modelling is still in progress. Although none of the models so far computed may be a perfect match for the thermal history of the reservoir, they all indicate that the intrusive heat source is young, close and large.

  6. Continental Scientific Drilling Program thermal regimes: comparative site assessment geology of five magma-hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.; Waters, A.C. (eds.)

    1980-10-01

    The geology and salient aspects of geophysics and hydrogeochemistry of five high-grade geothermal systems in the USA are reviewed. On the basis of this information, a target location is suggested for a deep (5- to 8-km) borehole that will maximize the amount of scientific information to be learned at each of the five geothermal areas.

  7. Archaeal and bacterial diversity in an arsenic-rich shallow-sea hydrothermal system undergoing phase separation

    Directory of Open Access Journals (Sweden)

    Roy Edward Price

    2013-07-01

    Full Text Available Phase separation is a ubiquitous process in seafloor hydrothermal vents, creating a large range of salinities. Toxic elements (e.g., arsenic partition into the vapor phase, and thus can be enriched in both high and low salinity fluids. However, investigations of microbial diversity at sites associated with phase separation are rare. We evaluated prokaryotic diversity in arsenic-rich shallow-sea vents off Milos Island (Greece by comparative analysis of 16S rRNA clone sequences from two vent sites with similar pH and temperature but marked differences in salinity. Clone sequences were also obtained for aioA-like functional genes (AFGs. Bacteria in the surface sediments (0 to 1.5 cm at the high salinity site consisted of mainly Epsilonproteobacteria (Arcobacter sp., which transitioned to almost exclusively Firmicutes (Bacillus sp. at ~10 cm depth. However, the low salinity site consisted of Bacteroidetes (Flavobacteria in the surface and Epsilonproteobacteria (Arcobacter sp. at ~10 cm depth. Archaea in the high salinity surface sediments were dominated by the orders Archaeoglobales and Thermococcales, transitioning to Thermoproteales and Desulfurococcales (Staphylothermus sp. in the deeper sediments. In contrast, the low salinity site was dominated by Thermoplasmatales in the surface and Thermoproteales at depth. Similarities in gas and redox chemistry suggest that salinity and/or arsenic concentrations may select for microbial communities that can tolerate these parameters. Many of the archaeal 16S rRNA sequences contained inserts, possibly introns, including members of the Euryarchaeota. Clones containing AFGs affiliated with either Alpha- or Betaproteobacteria, although most were only distantly related to published representatives. Most clones (89% originated from the deeper layer of the low salinity, highest arsenic site. This is the only sample with overlap in 16S rRNA data, suggesting arsenotrophy as an important metabolism in similar

  8. Evidence for degassing of fresh magma during the 2004-2008 eruption of Mount St. Helens: Subtle signals from the hydrothermal system

    Science.gov (United States)

    Bergfeld, Deborah; Evans, William C.; Spicer, Kurt R.; Hunt, Andrew G.; Kelly, Peter

    2017-01-01

    Results from chemical and isotopic analyses of water and gas collected between 2002 and 2016 from sites on and around Mount St. Helens are used to assess magmatic degassing related to the 2004-2008 eruption. During 2005 the chemistry of hot springs in The Breach of Mount St. Helens showed no obvious response to the eruption, and over the next few years, changes were subtle, giving only slight indications of perturbations in the system. By 2010 however, water chemistry, temperatures, and isotope compositions (δD and δ18O) clearly indicated some inputs of volatiles and heat associated with the eruption, but the changes were such that they could be attributed to a pre-existing, gas depleted magma. An increase of ~ 1.5‰ in the δ13C values of dissolved carbon in the springs was noted in 2006 and continued through 2009, a change that was mirrored by a similar shift in δ13C-CO2 in bubble gas emissions. These changes require input of a new source of carbon to the hydrothermal system and provide clear evidence of CO2 from an undegassed body of magma. Rising trends in 3He/4He ratios in gas also accompanied the increases in δ13C. Since 2011 maximum RC/RA values are ≥ 6.4 and are distinctly higher than 5 samples collected between 1986 and 2002, and provide additional evidence for some involvement of new magma as early as 2006, and possibly earlier, given the unknown time needed for CO2 and He to traverse the system and arrive at the springs.

  9. Hydrogeologic controls on saturation profiles in heat-pipe-like hydrothermal systems: numerical study

    Science.gov (United States)

    Pervin, Mollika; Ghergut, Iulia; Graf, Thomas; Peche, Aaron

    2016-04-01

    Most geothermal reservoirs are of the liquid-dominated type, and their unexploited-state pressure profile approximately follows the hydrostatic gradient. In very hot liquid-dominated systems, temperature typically follows a boiling-point-for-depth (BPD) relationship. By contrast, vapor-dominated systems exhibit (in their unexploited state) surprisingly small vertical gradients of temperature and pressure, such that a constantly high temperature is encountered over a large vertical thickness, while their pressure approximately follows vapour pressure, pvap(T°). This implies that (Pruess 1985, Truesdell and White 1973): (i) for a vapor-dominated reservoir to exist, it must be sealed laterally - otherwise it would be flooded by neighboring groundwaters with hydrostatic p profile, and (ii) liquid water should somehow be present in the whole system - otherwise p values would not be constrained by the pvap(T°) relationship for water. Historically, one of the most puzzling aspects of vapor-dominated systems was the large amount of heat flowing upwards, while vertical T° gradients remained negligible. This mechanism was deemed as 'heat pipe'(HP) (Eastman 1968): In the central zone of a vapor-dominated system, both vapor and liquid are mobile; vapor flows upwards, condenses at shallower depth, and the liquid condensate flows downwards. Due to the large amount of latent enthalpy released in vapor condensation, the vapor-liquid counter-flow can generate large rates of heat flow with negligible net mass transport (Pruess 1985). In order to be able to exploit two-phase (including vapor-dominated) reservoirs in a sustainable manner, one first needs to understand the conditions under which a two-phase (or a vapor-dominated) system has evolved naturally, and which have led to its present (quasi-) steady undisturbed state. Past studies have found that HP can exist in two distinct states, corresponding to liquid-dominated and vapor-dominated p profiles, respectively. Within this

  10. Porosity evolution, contact metamorphism, and fluid flow in the host basalts of the Skaergaard magma-hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Manning, C.E.

    1989-01-01

    Temporal and spatial variations in porosity during contact metamorphism of the basaltic country rocks to the Skaergaard intrusion in East Greenland resulted in a complex hydrological evolution of the metamorphic aureole. Contrasts in macroscopic porosities in different lithologies led to differences in mineralogical, bulk chemical, and oxygen isotopic alteration, and units with greater macroscopic porosities record larger fluid flux during metamorphism. Calculated Darcy velocities indicate that the horizontal component of fluid flow in the aureole was toward the intrusive contact. In the actinolite + chlorite zone time-integrated fluid flux was higher in aa units ({approximately} 300 kg cm{sup {minus}2}) than in massive units ({approximately} 130 kg cm{sup {minus}2}). Approximately equal time-integrated fluxes of respectively 4 and 5 kg cm{sup {minus}2} in aa and massive units in the pyroxene zone indicate that the volume of fluid flow in the higher grade rocks was independent of primary porosity. These results are consistent with inward fluid migration in the actinolite + chlorite zone through an open network of pores whose abundance varied as a function of primary lava morphology. At higher metamorphic grades fluid fluxes were lower and were independent of primary porosity, probably as a consequence of (1) channelization of fluids due to more extensive pore filling and (2) decreasing horizontal component of flow due to upward migration of fluids near the contact. The results of this study indicate that explicit provision for rock porosity aids interpretation of the nature of fluid flow during contact metamorphism in magma-hydrothermal systems.

  11. Microbial Diversity of Carbonate Chimneys at the Lost City Hydrothermal Field: Implications for Life-Sustaining Systems in Peridotite Seafloor Environments

    Science.gov (United States)

    Schrenk, M. O.; Cimino, P.; Kelley, D. S.; Baross, J. A.

    2002-12-01

    The Lost City Hydrothermal Field (LCHF) is a novel peridotite-hosted vent environment discovered in Dec. 2000 at 30 N near the Mid-Atlantic Ridge. This field contains multiple large (up to 60 m), carbonate chimneys venting high pH (9-10), moderate temperature (45-75 C) fluids. The LCHF is unusual in that it is located on 1.5 my-old oceanic crust, 15 km from the nearest spreading axis. Hydrothermal flow in this system is believed to be driven by exothermic serpentinization reactions involving iron-bearing minerals in the underlying seafloor. The conditions created by such reactions, which include significant quantities of dissolved methane and hydrogen, create habitats for microbial communities specifically adapted to this unusual vent environment. Ultramafic, reducing hydrothermal environments like the LCHF may be analogous to geologic settings present on the early Earth, which have been suggested to be important for the emergence of life. Additionally, the existence of hydrothermal environments far away from an active spreading center expands the range of potential life-supporting environments elsewhere in the solar system. To study the abundance and diversity of microbial communities inhabiting the environments that characterize the LCHF, carbonate chimney samples were analyzed by microscopic and molecular methods. Cell densities of between 105 and 107 cells/g were observed within various samples collected from the chimneys. Interestingly, 4-11% of the microbial population in direct contact with vent fluids fluoresced with Flavin-420, a key coenzyme involved in methanogenesis. Enrichment culturing from chimney material under aerobic and anaerobic conditions yielded microorganisms in the thermophilic and mesophilic temperature regimes in media designed for methanogenesis, methane-oxidation, and heterotrophy. PCR analysis of chimney material indicated the presence of both Archaea and Eubacteria in the carbonate samples. SSU rDNA clone libraries constructed from the

  12. 现代海底热液场低温弥散流区微生物生态的研究进展%A Review of Microbial Ecology in Low-Temperature Diffuse Flow Area of Modern Submarine Hydrothermal System

    Institute of Scientific and Technical Information of China (English)

    李季伟; 周怀阳; 彭晓彤; 陈智强; 孙治雷; 李江涛; 陈顺; 章力学

    2012-01-01

    The development of microbial ecology in the areas where low-temperature hydrothermal diffuse flow is dominant has presently become one of the hot scientific topics on the study of submarine hydrothermal system. Many surveys have shown that a large number of chemolithautotrophic microorganisms are present in the low-temperature hydrothermal diffuse flow areas and they obtain energy for metabolism from the redox of elements such as sulfur and Fe (II) supplied by hydrothermal fluids. Their distributions are closely related to the physicochemical conditions of low-temperature hydrothermal fluids. These discoveries have greatly enriched our knowledge of microbial ecology in the low-temperature hydrothermal diffuse flow areas and enhanced our understandings about the relationship between the key geochemical processes and the microbial metabolism in the submarine hydrothermal system. In addition, the low-temperature hydrothermal fluid may be a window for studying the biosphere in the deep oceanic crust, through which the metabolism approach of the life within the oceanic crust could be learned and the interaction mechanisms between the microorganisms and the fluids and rocks within the oceanic crust might be understood.%现代海底低温热液弥散流区微生物生态的发育情况已经成为当前热液系统研究关注的热点之一.大量的分析表明在低温热液弥散流区赋存着丰富的化能自养微生物,以硫、铁等元素的氣化还原反应获取新陈代谢能量,这些微生物的分布与低温热液流体的物理化学条件有着密切的联系.这些发现极大地丰富了我们对低温弥散流区微生物生态、关键地球化学过程与微生物新陈代谢耦合关系的认识.此外,低温热液流体是研究洋壳深部生物圈的窗口,通过这个窗口可以了解地壳内部生命的新陈代谢方式,进而理解地球内部微生物与洋壳内部流体、岩石之间的相互作用机制.

  13. Methanococcus igneus sp. nov., a novel hyperthermophilic methanogen from a shallow submarine hydrothermal system

    Science.gov (United States)

    Burggraf, S.; Fricke, H.; Neuner, A.; Kristjansson, J.; Rouvier, P.; Mandelco, L.; Woese, C. R.; Stetter, K. O.

    1990-01-01

    A novel hyperthermophilic strictly chemolithoautotrophic member of the genus Methanococcus was isolated from a shallow (depth: 106 m) submarine vent system at the Kolbeinsey ridge, Iceland. The isolate grew between 45 and 91 degrees C with an optimum around 88 degrees C (doubling time: 25 min). It differs from Methanococcus jannaschii in its 16S rRNA sequence, its non-hybridizing DNA, and its selenium-independent growth. Therefore, the isolate represents a new species which we name Methanococcus igneus. Type strain is isolate "Kol 5" (DSM 5666).

  14. The Effect of Sulfur Fugacity on Pt, Pd and Au in Magmatic-Hydrothermal Systems

    Science.gov (United States)

    Bell, A.; Simon, A.

    2009-05-01

    We have constrained experimentally the effect of sulfur fugacity (fS2) and sulfide saturation on the fractionation and partitioning behavior of Pt, Pd and Au in a felsic silicate melt + sulfide crystal/melt + oxide + supercritical aqueous fluid phase + Pt + Pd + Au system. Experiments were performed at 800°C, 150 MPa, with oxygen fugacity (fO2) fixed at approximately the nickel + nickel oxide buffer (NNO). Sulfur fugacity in the experiments was varied five orders of magnitude from approximately logfS2 = 0 to logfS2 = -5 by using two different sulfide phase assemblages. Sulfide assemblage one consisted initially of chalcopyrite plus pyrrhotite and assemblage two consisted of chalcopyrite plus bornite. At run conditions, in both assemblages, pyrrhotite transformed compositionally to monosulfide solid solution (mss), chalcopyrite to intermediate solid solution (Iss), and in assemblage two chalcopyrite and bornite formed a sulfide melt. Run- product silicate glass (i.e., quenched silicate melt) and crystalline materials were analyzed by using both electron probe microanalysis (EPMA) for major elements and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for major and trace elements. The measured concentrations of Pt, Pd, and Au in quenched silicate melt in runs with logfS2 values ranging from approximately 0 to -5, do not exhibit any apparent dependence on the dissolved sulfur content of the melt. The measured Pt, Pd and Au concentrations in mss vary as a function of fS2. The measured Pt, Pd and Au concentrations in Iss do not appear to be dependent on fS2. The system variables fS2 and fO2, working in concert with each other, control the stable magmatic sulfide phase assemblage. Additionally, the system fS2 strongly influences the solubility of Pt, Pd, and Au as lattice bound components in some common crystalline magmatic sulfide phases. Both the stable magmatic sulfide phase assemblage and the solubility of Pt, Pd, and Au as constituents in

  15. Hydrothermal Liquefaction Treatment Preliminary Hazard Analysis Report

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, Peter P.; Wagner, Katie A.

    2015-08-31

    A preliminary hazard assessment was completed during February 2015 to evaluate the conceptual design of the modular hydrothermal liquefaction treatment system. The hazard assessment was performed in 2 stages. An initial assessment utilizing Hazard Identification and Preliminary Hazards Analysis (PHA) techniques identified areas with significant or unique hazards (process safety-related hazards) that fall outside of the normal operating envelope of PNNL and warranted additional analysis. The subsequent assessment was based on a qualitative What-If analysis. This analysis was augmented, as necessary, by additional quantitative analysis for scenarios involving a release of hazardous material or energy with the potential for affecting the public.

  16. Combined effect of carbon dioxide and sulfur on vapor-liquid partitioning of metals in hydrothermal systems

    Science.gov (United States)

    Kokh, Maria A.; Lopez, Mathieu; Gisquet, Pascal; Lanzanova, Aurélie; Candaudap, Frédéric; Besson, Philippe; Pokrovski, Gleb S.

    2016-08-01

    Although CO2 is a ubiquitous volatile in geological fluids typically ranging from a few to more than 50 wt%, its effect on metal vapor-liquid fractionation during fluid boiling and immiscibility phenomena in the Earth's crust remains virtually unknown. Here we conducted first experiments to quantify the influence of CO2 on the partition of different metals in model water + salt + sulfur + CO2 systems at 350 °C and CO2 pressures up to 100 bar, which are typical conditions of formation of many hydrothermal ore deposits. In addition, we performed in situ Raman spectroscopy measurements on these two-phase systems, to determine sulfur and carbon speciation in the liquid and vapor phases. Results show that, in S-free systems and across a CO2 concentration range of 0-50 wt% in the vapor phase, the absolute vapor-liquid partitioning coefficients of metals (Kvap/liq = Cvap/Cliq, where C is the mass concentration of the metal in the corresponding vapor and liquid phase) are in the range 10-6-10-5 for Mo; 10-4-10-3 for Na, K, Cu, Fe, Zn, Au; 10-3-10-2 for Si; and 10-4-10-1 for Pt. With increasing CO2 from 0 to 50 wt%, Kvap/liq values decrease for Fe, Cu and Si by less than one order of magnitude, remain constant within errors (±0.2 log unit) for Na, K and Zn, and increase by 0.5 and 2 orders of magnitude, respectively for Au and Pt. The negative effect of CO2 on the partitioning of some metals is due to weakening of hydration of chloride complexes of some metals (Cu, Fe) in the vapor phase and/or salting-in effects in the liquid phase (Si), whereas both phenomena are negligible for complexes of other metals (Na, K, Zn, Mo). The only exception is Pt (and in a lesser extent Au), which partitions significantly more to the vapor of S-free systems in the presence of CO2, likely due to formation of volatile carbonyl (CO) complexes. In the S-bearing system, with H2S content of 0.1-1.0 wt% in the vapor, Kvap/liq values of Cu, Fe, Mo, and Au are in the range 0.01-0.1, those of Pt 0

  17. Hydrothermalism in the Mediterranean Sea

    Science.gov (United States)

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

    1999-08-01

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

  18. In situ ore formation experiment: Amino acids and amino sugars trapped in artificial chimneys on deep-sea hydrothermal systems at Suiyo Seamount, Izu-Bonin Arc, Pacific Ocean

    CERN Document Server

    Takano,; Marumo,; K.,; Ebashi,; T.,; Gupta,; P., L; Kawahata,; H.,; Kobayashi,; K.,; Yamagishi,; A.,; Kuwabara,; T,

    2013-01-01

    The present study reports on the bio-organic composition of a deep-sea venting hydrothermal system originating from arc volcanism; the origin of the particulates in hydrothermal fluids from the Suiyo Seamount in the southern Izu-Bonin (Ogasawara) Arc is discussed with regard to amino compounds. Chimney samples on deep-sea hydrothermal systems and core samples at Suiyo Seamount were determined for amino acids, and occasionally amino sugars. Two types of chimney samples were obtained from active hydrothermal systems by submersible vehicles: one was natural chimney (NC) on a hydrothermal natural vent; the other was artificial chimneys (AC), mainly formed by the growth and deposition of sulfide-rich particulate components in a Kuwabara-type in situ incubator (KI incubator). Total hydrolyzed amino acids (THAA) and hydrolyzed hexosamines (HA) in AC ranged from 10.7 nmol/g to 64.0 nmol/g and from 0 nmol/g to 8.1 nmol/g, respectively, while THAA in hydrothermally altered core samples ranged from 26.0 nmol/g to 107.4 ...

  19. 3D Geothermal Modelling of the Mount Amiata Hydrothermal System in Italy

    Directory of Open Access Journals (Sweden)

    Paolo Fulignati

    2014-11-01

    Full Text Available In this paper we build a subsurface model that helps in visualizing and understanding the structural framework, geology and their interactions with the Mt. Amiata geothermal system. Modelling in 3D provides the possibility to interpolate the geometry of structures and is an effective way of understanding geological features. The 3D modelling approach appears to be crucial for further progress in the reconstruction of the assessment of the geothermal model of Mt. Amiata. Furthermore, this model is used as the basis of a 3D numerical thermo-fluid-dynamic model of the existing reservoir(s. The integration between borehole data and numerical modelling results allows reconstructing the temperature distribution in the subsoil of the Mt. Amiata area.

  20. Subrepository scale hydrothermal analysis in support of total system performance assessment at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, S. [CRWMS M& O/INTERA Inc., Las Vegas, NV (United States)

    1994-12-31

    A coupled thermo-hydrologic model is developed to investigate the impact of emplacing high-level nuclear wastes on heat and fluid flow at the subrepository scale, and to develop abstracted results for input to the current total system performance assessment (TSPA) of Yucca Mountain. Numerical computations are carried out in 2-D axisymmetric geometry, using a range of thermal loads, to generate spatial/temporal evolutions in temperature and saturation fields within individual emplacement panels. These results are analyzed to understand the general nature of liquid movement in the repository due to waste heat, and also to define various temperature dependent mechanistic and phenomenological coefficients for predicting waste package and geosphere performance.

  1. Water and gas geochemistry of the Calatrava Volcanic Province (CVP) hydrothermal system (Ciudad Real, central Spain)

    Science.gov (United States)

    Vaselli, Orlando; Nisi, Barbara; Tassi, Franco; Giannini, Luciano; Grandia, Fidel; Darrah, Tom; Capecchiacci, Francesco; del Villar, Pèrez

    2013-04-01

    An extensive geochemical and isotopic investigation was carried out in the water and gas discharges of the Late Miocene-Quaternary Calatrava Volcanic Province (CVP) (Ciudad Real, Spain) with the aim reconstruct the fluid circulation in the area. CVP consists of a series of scattered (monogenetic) vents from where alkaline lava flows and pyroclastic deposits formed in two different periods. The first stage (8.7-6.4 Ma) mainly included ultra-potassic mafic extrusives, whilst the second stage (4.7-1.75 Ma) prevalently originated alkaline and ultra-alkaline volcanics. Both stages were followed by a volcanic activity that extended up to 1.3 and 0.7 Ma, respectively. This area can likely be regarded as one of the most important emitting zones of CO2 in the whole Peninsular Spain along with that of Selva-Emporda in northeastern Spain (Cataluña) and it can be assumed as one of the best examples of natural analogues of CO2 leakages in Spain. This latter aspect is further evidenced by the relatively common water-gas blast events that characterize the CCVF. In the last few years the presence of a CO2-pressurized reservoir at a relatively shallow level as indeed caused several small-sized explosion particularly during the drilling of domestic wells. The fluid discharging sites are apparently aligned along well-defined directions: NW-SE and NNW-SSE and subordinately, ENE-WSW, indicating a clear relationship between the thermal discharges and the volcanic centers that also distribute along these lineaments. The CVP waters are mostly hypothermal (up to 33 °C) and are generally Mg(Ca)-HCO3 in composition and occasionally show relatively high concentrations of Fe and Mn, with pH and electrical conductivity down to 5.5 and up to 6.5 mS/cm, respectively. The oxygen and hydrogen isotopes suggest a meteoric origin for these waters. The mantle source of these volcanic products is apparently preserved in the many CO2-rich (up to 990,000 mmol/mol) gas discharges that characterize CVP

  2. Colonization of plant substrates at hydrothermal vents and cold seeps in the northeast Atlantic and Mediterranean and occurrence of symbiont-related bacteria

    Directory of Open Access Journals (Sweden)

    Kamil M Szafranski

    2015-02-01

    Full Text Available Reducing conditions with elevated sulphide and methane concentrations in ecosystems such as hydrothermal vents, cold seeps or organic falls, are suitable for chemosynthetic primary production. Understanding processes driving bacterial diversity, colonization and dispersal is of prime importance for deep-sea microbial ecology. This study provides a detailed characterization of bacterial assemblages colonizing plant-derived substrates using a standardised approach over a geographic area spanning the North-East Atlantic and Mediterranean. Wood and alfalfa substrates in colonization devices were deployed for different periods at 8 deep-sea chemosynthesis-based sites in 4 distinct geographic areas. Pyrosequencing of a fragment of the 16S rRNA-encoding gene was used to describe bacterial communities. Colonization occurred within the first 14 days. The diversity was higher in samples deployed for more than 289 days. After 289 days, no relation was observed between community richness and deployment duration, suggesting that diversity may have reached saturation sometime in between. Communities in long-term deployments were different, and their composition was mainly influenced by the geographical location where devices were deployed. Numerous sequences related to horizontally-transmitted chemosynthetic symbionts of metazoans were identified. Their potential status as free-living forms of these symbionts was evaluated based on sequence similarity and monophyly with demonstrated symbionts. Results suggest that some free-living forms of metazoan symbionts or their close relatives, such as the epsilonproteobacterium associated with the shrimp Rimicaris exoculata, are efficient colonizers of plant substrates at vents and seeps.

  3. Colonization of plant substrates at hydrothermal vents and cold seeps in the northeast Atlantic and Mediterranean and occurrence of symbiont-related bacteria.

    Science.gov (United States)

    Szafranski, Kamil M; Deschamps, Philippe; Cunha, Marina R; Gaudron, Sylvie M; Duperron, Sébastien

    2015-01-01

    Reducing conditions with elevated sulfide and methane concentrations in ecosystems such as hydrothermal vents, cold seeps or organic falls, are suitable for chemosynthetic primary production. Understanding processes driving bacterial diversity, colonization and dispersal is of prime importance for deep-sea microbial ecology. This study provides a detailed characterization of bacterial assemblages colonizing plant-derived substrates using a standardized approach over a geographic area spanning the North-East Atlantic and Mediterranean. Wood and alfalfa substrates in colonization devices were deployed for different periods at 8 deep-sea chemosynthesis-based sites in four distinct geographic areas. Pyrosequencing of a fragment of the 16S rRNA-encoding gene was used to describe bacterial communities. Colonization occurred within the first 14 days. The diversity was higher in samples deployed for more than 289 days. After 289 days, no relation was observed between community richness and deployment duration, suggesting that diversity may have reached saturation sometime in between. Communities in long-term deployments were different, and their composition was mainly influenced by the geographical location where devices were deployed. Numerous sequences related to horizontally-transmitted chemosynthetic symbionts of metazoans were identified. Their potential status as free-living forms of these symbionts was evaluated based on sequence similarity with demonstrated symbionts. Results suggest that some free-living forms of metazoan symbionts or their close relatives, such as Epsilonproteobacteria associated with the shrimp Rimicaris exoculata, are efficient colonizers of plant substrates at vents and seeps.

  4. Hydrothermal preparation and crystal habit of X-zeolite powder

    Institute of Scientific and Technical Information of China (English)

    SHEN Shao-hua; ZHANG Shu-gen; WANG Da-wei; FANG Ke-ming

    2005-01-01

    The preparation of X-zeolite powder was investigatedin hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microscope and infrared ray. The results show that X-zeolite powder with uniform granularity and intact crystal shape can be obtained in hydrothermal system of acid-treated stellerite-NaOH-NaAl(OH)4-H2O; the crystallite size is in the range of 2 - 3μm. The best reaction time of hydrothermal preparation is 6 h. The formation phases of X-zeolite crystal are as follows: dissolution of feedstocks → formation of [SiO4]4- and [AlO4]5- tetrahedron, many-membered ring,β cage → formation of crystal nucleus and nano-particle → aggregation growth of nano-particle → coalescence growth of crystallite. The crystal habits of X-zeolite are intimately related with crystallization orientation ofβ cage in crystal and with its coupling stability on every crystal face family.

  5. The Lost City hydrothermal system: Constraints imposed by vent fluid chemistry and reaction path models on subseafloor heat and mass transfer processes

    Science.gov (United States)

    Seyfried, W. E.; Pester, Nicholas J.; Tutolo, Benjamin M.; Ding, Kang

    2015-08-01

    Since the first reported discovery of the Lost City hydrothermal system in 2001, it was recognized that seawater alteration of ultramafic rocks plays a key role in the composition of the coexisting vent fluids. The unusually high pH and high concentrations of H2 and CH4 provide compelling evidence for this. Here we report the chemistry of hydrothermal fluids sampled from two vent structures (Beehive: ∼90-116 °C, and M6: ∼75 °C) at Lost City in 2008 during cruise KNOX18RR using ROV Jason 2 and R/V Revelle assets. The vent fluid chemistry at both sites reveals considerable overlap in concentrations of dissolved gases (H2, CH4), trace elements (Cs, Rb, Li, B and Sr), and major elements (SO4, Ca, K, Na, Cl), including a surprising decrease in dissolved Cl, suggesting a common source fluid is feeding both sites. The absence of Mg and relatively high concentrations of Ca and sulfate suggest solubility control by serpentine-diopside-anhydrite, while trace alkali concentrations, especially Rb and Cs, are high, assuming a depleted mantle protolith. In both cases, but especially for Beehive vent fluid, the silica concentrations are well in excess of those expected for peridotite alteration and the coexistence of serpentine-brucite at all reasonable temperatures. However, both the measured pH and silica values are in better agreement with serpentine-diopside-tremolite-equilibria. Geochemical modeling demonstrates that reaction of plagioclase with serpentinized peridotite can shift the chemical system away from brucite and into the tremolite stability field. This is consistent with the complex intermingling of peridotite and gabbroic bodies commonly observed within the Atlantis Massif. We speculate the existence of such plagioclase bearing peridotite may also account for the highly enriched trace alkali (Cs, Rb) concentrations in the Lost City vent fluids. Additionally, reactive transport modeling taking explicit account of temperature dependent rates of mineral

  6. Hydrothermal systems in two areas of the Jemez volcanic field: Sulphur Springs and the Cochiti mining district

    Energy Technology Data Exchange (ETDEWEB)

    WoldeGabriel, G.

    1989-03-01

    K/Ar dates and oxygen isotope data were obtained on 13 clay separates (<2 ..mu..m) of thermally altered mafic and silicic rocks from the Cochiti mining district (SE Jemez Mountains) and Continental Scientific Drilling Project (CSDP) core hole VC-2A (Sulphur Springs, Valles caldera). Illite with K/sub 2/O contents of 6.68%--10.04% is the dominant clay in the silicic rocks, whereas interstratified illite/smectites containing 1.4%--5.74% K/sub 2/O constitute the altered andesites. Two hydrothermal alteration events are recognized at the Cochiti area (8.07 m.y., n = 1, and 6.5--5.6 m.y., n = 6). The older event correlates with the waning stages of Paliza Canyon Formation andesite volcanism (greater than or equal to13 to less than or equal to8.5 m.y.), whereas the younger event correlates with intrusions and gold- and silver-bearing quartz veins associated with the Bearhead Rhyolite (7.54--5.8 m.y.). The majority of K/Ar dates in the hydrothermally altered, caldera-fill rocks of core hole VC-2A (0.83--0.66 m.y., n = 4) indicate that hydrothermal alteration developed contemporaneously with resurgence and ring fracture Valles Rhyolite domes (0.89--0.54 m.y.). One date of 0 +- 0.10 m.y. in acid-altered landslide debris of postcaldera tuffs from the upper 13 m of the core hole probably correlates with Holocene hydrothermal activity possibly associated with the final phases of the Valles Rhyolite (0.13 m.y.).

  7. Fluid-Dacite Interaction in the PACMANUS Subseafloor Hydrothermal System - Preliminary Results From Secondary Mineral Chemistry and Geochemical Modeling

    Science.gov (United States)

    Yeats, C. J.; Bach, W.; Vanko, D. A.; Roberts, S.; Lackschewitz, K.; Paulick, H.

    2001-12-01

    During Ocean Drilling Program Leg 193, several holes (as deep as 386 meters below sea floor) intersected variably altered and veined dacites on Pual Ridge in the eastern Manus back-arc basin. The hydothermal alteration is complex and multi-stage, and includes pervasive alteration and alteration halos along anhydrite±pyrite±quartz veins. Our preliminary interpretation is that an early pervasive "chloritic" alteration (chlorite, chlorite/smectite, quartz, +/-albite, +/-magnetite) is overprinted locally by illite-pyrophyllite-anhydrite+/-diaspore alteration followed by silica (quartz and cristobalite) flooding. Two drill holes at Snowcap, a site of diffuse venting, reveal alteration profiles of strongly illite-pyrophyllite-anhydrite altered rocks in the shallow parts grading downwards into rocks that show dominant chloritic alteration. At Roman Ruins, a site of discrete venting, K-feldspar and illite-smectite mixed layer phases are abundant and magnetite is rare. K-feldspar appears to be part of the "chloritic" alteration assemblage. Anhydrite is locally abundant but generally less common than at Snowcap. There is a strong lateral heterogeneity in basement alteration as revealed by the differences between sites in the depths of cristobalite-quartz transition and the zones of prevailing alteration styles. Geochemical modeling suggests that the rocks have been altered at temperatures of about 250 to 300° C under variable fluid-to-rock ratios. While all the mineral assemblages are consistent with quartz/cristobalite saturation of the fluids, the formation of diaspore must be related to episodic interaction of the rocks with fluids highly undersaturated in quartz. The early stage of chloritic alteration represents interaction of the dacites with fluids of a fairly high pH ({>}4). In contrast, the occurrence of pyrophyllite and local diaspore suggests lower pH fluid ({hydrothermal stages. A zone of abundant alunite at 350 m deep in the basement at Snowcap may represent

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

    Science.gov (United States)

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

    2015-12-01

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

  9. Electricity generation from hydrothermal vents

    Science.gov (United States)

    Aryadi, Y.; Rizal, I. S.; Fadhli, M. N.

    2016-09-01

    Hydrothermal vent is a kind of manifestation of geothermal energy on seabed. It produces high temperature fluid through a hole which has a diameter in various range between several inches to tens of meters. Hydrothermal vent is mostly found over ocean ridges. There are some 67000 km of ocean ridges, 13000 of them have been already studied discovering more than 280 sites with geothermal vents. Some of them have a thermal power of up to 60 MWt. These big potential resources of energy, which are located over subsea, have a constraint related to environmental impact to the biotas live around when it becomes an object of exploitation. Organic Rankine Cycle (ORC) is a method of exploiting heat energy to become electricity using organic fluid. This paper presents a model of exploitation technology of hydrothermal vent using ORC method. With conservative calculation, it can give result of 15 MWe by exploiting a middle range diameter of hydrothermal vent in deep of 2000 meters below sea level. The technology provided here really has small impact to the environment. With an output energy as huge as mentioned before, the price of constructing this technology is low considering the empty of cost for drilling as what it should be in conventional exploitation. This paper also presents the comparison in several equipment which is more suitable to be installed over subsea.

  10. Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments

    Science.gov (United States)

    Kitadai, Norio

    2015-12-01

    Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

  11. Hydrothermal alteration of impact melt sheets with implications for Mars

    Science.gov (United States)

    Newsom, H. E.

    1980-01-01

    A model of the interaction of water with an impact melt sheet is constructed to explain the presence of hydrothermal alteration, fluid flow channels, and the redistribution of volatile elements in terrestrial melt sheets. A calculation of the amount of water vaporized beneath a melt sheet with a large fraction of melt results in a maximum total steam/melt sheet ratio of 23% by weight. The model also applies to Martian impact melt sheets, which have a total volume greater than a global layer 60 m thick. Hydrothermal circulation of steam in Martian melt sheets may have produced iron-rich alteration clays, ferric hydroxides, and near-surface accumulations of salts. The ability of vapor-dominated hydrothermal systems to concentrate sulfate relative to chloride is consistent with the high sulfate to chloride ratio found in the Martian soil by the Viking landers. A major fraction of the Martian soil may consist of the erosion products of hydrothermally altered impact melt sheets.

  12. Iceland Deep Drilling Project: (V) Isotopic Evidence of Hydrothermal Exchange and Seawater Ingress from Alteration Minerals in the Reykjanes Geothermal System

    Science.gov (United States)

    Marks, N. E.; Zierenberg, R. A.; Schiffman, P.

    2009-12-01

    The Reykjanes geothermal system is a seawater recharged hydrothermal system located on the landward extension of the Mid-Atlantic Ridge in Iceland. Fluid compositions in the system have evolved through time as a result of changing proportions of meteoric water as well as differing pressure and temperature conditions imposed by glaciation (Sveinbjornsdottir, 1986; Fridleifsson et al., 2005; Marks et al., 2009). Samples from the deepest part of Reykjanes well RN-17 include greenschist to pyroxene hornfels facies assemblages, suggesting seawater penetration into a part of the system that is close to the high temperature reaction zone. Electron microprobe studies of drill cuttings reveal intense alteration of hyaloclastites with calc-silicate alteration assemblages comprising calcic hydrothermal plagioclase, grandite garnet, prehnite, epidote, hydrothermal clinopyroxene, and titanite. In contrast, crystalline basalts and intrusive rocks display a wide range in alteration intensity from essentially unaltered to pervasive and nearly complete replacement of feldspar and pyroxene. Epidote is widely distributed throughout the RN-17 samples and fills veins and vugs, replaces glass in hyaloclastites and the interstitial matrix of basalt samples, and is also an alteration product of primary plagioclase. 87Sr/86Sr values of individual epidote grains measured by LA-ICPMS were typically 0.7045-0.7050, but ranged as high as 0.7073 in individual grains. Anhydrite is widespread in shallow portions of the Reykjanes system to about 1500 m. 87Sr/86Sr values of anhydrite from the Reykjanes geothermal system range from 0.7044-0.7053, and gypsum values range from 0.7093 to 0.7094. The Sr isotopic ratios of alteration minerals are shifted from basaltic values (0.7030-0.7034; O’Nions and Grönvold, 1973; Sun and Jahn, 1975) toward seawater values (0.70916; Palmer and Edmond, 1989). This suggests that seawater Sr is able to penetrate deep within the geothermal system, and that seawater Sr

  13. High-resolution Topography of PACMANUS and DESMOS Hydrothermal Fields in the Manus Basin through ROV "FAXIAN"

    Science.gov (United States)

    Luan, Z.; Ma, X.; Yan, J.; Zhang, X.; Zheng, C.; Sun, D.

    2016-12-01

    High-resolution topography can help us deeply understand the seabed and related geological processes (e.g. hydrothermal/cold spring systems) in the deep sea areas. However, such studies are rare in China due to the limit of deep-sea detection technology. Here, we report the advances of the application of ROV in China and the newly measured high-resolution topographical data in PACMANUS and DESMOS hydrothermal fields. In June 2015, the ROV "FAXIAN" with a multibeam system (Kongsberg EM2040) was deployed to measure the topography of PACMANUS and DESMOS hydrothermal fields in the Manus basin. A composite positioning system on the ROV provided long baseline (LBL) navigation and positioning during measurements, giving a high positioning accuracy (better than 0.5m). The raw bathymetric data obtained were processed using CARIS HIPS (version 8.1). Based on the high-resolution data, we can describe the topographical details of the PACMANUS and DESMOS hydrothermal fields. High-resolution terrain clearly shows the detailed characters of the topography in the PACMANUS hydrothermal field, and some cones are corresponding to the pre discovered hydrothermal points and volcanic area. Most hydrothermal points in the PACMANUS hydrothermal field mainly developed on the steep slopes with a gradient exceeding 30 °. In contrast, the DESMOS field is a caldera that is approximately 250 m deep in the center with an E-W diameter of approximately1 km and a N-S diameter of approximately 2 km. The seafloor is much steeper on the inner side of the circular fracture. Two highlands occur in the northern and the southern flanks of the caldera. Video record indicated that pillow lava, sulfide talus, breccia, anhydrite, outcrops, and sediment all appeared in the DESMOS field. This is the first time for the ROV "FAXIAN" to be used in near-bottom topography measurements in the hydrothermal fields, opening a window of deep-sea researches in China.

  14. Geochemistry of sericite and chlorite in well 14-2 Roosevelt Hot Springs geothermal system and in mineralized hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Ballantyne, J.M.

    1980-06-01

    Chemical compositions of chlorite and sericite from one production well in the Roosevelt geothermal system have been determined by electron probe methods and compared with compositions of chlorite and sericite from porphyry copper deposits. Modern system sericite and chlorite occur over a depth interval of 2 km and a temperature interval of 250/sup 0/C.

  15. Planning of the power hydrothermal system operation - alternatives for the modelling and uncertainties treatment; Planejamento da operacao de sistemas hidrotermicos de potencia - alternativas de modelagem e o tratamento das incertezas

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Andre Flavio Soares; Bajay, Sergio Valdir [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica]|[Universidade Estadual de Campinas, SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico (NIPE)]. E-mails: apereira@fem.unicamp.br; bajay@fem.unicamp.br; Barbosa, Paulo Sergio Franco [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Civil]|[Universidade Estadual de Campinas, SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico (NIPE)]. E-mail: franco@fec.unicamp.br

    2006-07-01

    The complexity of the operation scheduling of hydrothermal power systems lies, among other factors, in the interconnection between the operation decision in a certain stage and the future consequences of such decision. The operation of a hydrothermal power system comprises from the supervision and real time control of the generation and transport of electricity, to aspects as the modelling of the uncertainties concerning the future stream flows and the optimised management of the hydro power plant reservoirs. This work addresses a general formulation of the operation scheduling problem of hydrothermal power systems; a brief presentation of the various optimization techniques which can be used in its solution; and a discussion about the main alternatives that has been adopted to model the problem and to deal with its main uncertainties. (author)

  16. Assessing microbial processes in deep-sea hydrothermal systems by incubation at in situ temperature and pressure

    Science.gov (United States)

    McNichol, Jesse; Sylva, Sean P.; Thomas, François; Taylor, Craig D.; Sievert, Stefan M.; Seewald, Jeffrey S.

    2016-09-01

    At deep-sea hydrothermal vents, a large source of potential chemical energy is created when reducing vent fluid and oxidizing seawater mix. In this environment, chemolithoautotrophic microbes catalyze exergonic redox reactions which in turn provide the energy needed to fuel their growth and the fixation of CO2 into biomass. In addition to producing new organic matter, this process also consumes compounds contained both in vent fluid and entrained seawater (e.g. H2, NO3-). Despite their biogeochemical importance, such reactions have remained difficult to quantify due to methodological limitations. To address this knowledge gap, this study reports a novel application of isobaric gas-tight fluid samplers for conducting incubations of hydrothermal vent fluids at in situ temperature and pressure. Eighteen 24 h incubations were carried out, representing seven distinct conditions that examine amendments consisting of different electron donors and acceptors. Microbial activity was observed in all treatments, and time series chemical measurements showed that activity was limited by electron acceptor supply, confirming predictions based on geochemical data. Also consistent with these predictions, the presence of nitrate increased rates of hydrogen consumption and yielded ammonium as a product of nitrate respiration. The stoichiometry of predicted redox reactions was also determined, revealing that the sulfur and nitrogen cycles are incompletely understood at deep-sea vents, and likely involve unknown intermediate redox species. Finally, the measured rates of redox processes were either equal to or far greater than what has been reported in previous studies where in situ conditions were not maintained. In addition to providing insights into deep-sea hydrothermal vent biogeochemistry, the methods described herein also offer a practical approach for the incubation of any deep-sea pelagic sample under in situ conditions.

  17. A stochastic approach to long term operation planning of hydrothermal systems; Uma abordagem estocastica para o planejamento a longo prazo da operacao de sistemas hidrotermicos

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marinho G. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Ciencias Matematicas; Soares, Secundino; Cruz Junior, Gelson da; Vinhal, Cassio D.N. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Eletrica

    1996-01-01

    This paper is concerned with long term operation of hydro-thermal power systems. The problem is approached by a deterministic optimization technique coupled to an inflow forecasting model in open-loop feedback framework in monthly basis. The paper aims to compare the solution obtained by this approach and Stochastic Dynamic Programming (SDP), which has been accepted for over than two decades as the better solution to deal with inflow uncertainty in long term planning. The comparison was carried out in systems with a single plant, simulating the operation throughout a period of five years under the historical inflow conditions and evaluating the cost of the complementary thermal generation. Results show that the proposed approach can handle uncertainty as effectively as SDP. Furthermore, it does not require modeling simplification, such as composite reservoirs, to deal with multi hydro plant systems. 10 refs., 1 tab.

  18. The formation of titania polymorphs under hydrothermal condition

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Yanqing(郑燕青); SHI; Erwei(施尔畏); LI; Wenjun(李汶军); CHEN; Zhizhan(陈之战); ZHONG; Weizhuo(仲维卓); HU; Xingfang(胡行方)

    2002-01-01

    The formation process of crystal polymorphs of titania under hydrothermal condition is studied.According to the experimental results and theoretic analysis,the formation process of crystal polymorphs can be described as a unit process.It includes the formation of growth units,the formation of nuclei through the polymerization of growth unit,and the growth of crystallites.The influence of the environmental phase and growth conditions on the formation of polymorphs is reflected in the changes of the structures of growth units.For example,when changing the pH of the reaction medium,the structure of growth unit with the highest stable energy in the hydrothermal system changes.Then different titania polymorphs can be prepared.The absorption,movement,crystallization or desorption of the growth unit are related to crystalline structure.On the other hand,the formation of crystal inner defects is related to the disturbance of the crystallizing process.``

  19. Dissolubility of Hydroxyapatite Powder under Hydrothermal Condition

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dissolubility of hydroxyapatite(HA) in the hydrothermal solution was investigated in Morey-type autoclave over a temperature range of 150 to 350 ℃ and the pH value range of 5 to 9. It is shown that the dissolubility of HA is determined as a function of temperature and time under a constant filling ratio of autoclave, and the temperature coefficient for the solubility of HA is positive. The equilibrium time attained in the hydrothermal solution is shortened with the increase of hydrothermal temperature, and the effect of temperature on the solubility is obviously stronger than that of pH value. The solubility data suggest that HA has higher dissolubility in the HA-H2O system under the hydrothermal condition than that under the normal temperature-pressure.

  20. Hydrothermal Manganese Mineralization Near the Samoan Hotspot

    Science.gov (United States)

    Hein, J. R.; Staudigel, H.; Koppers, A.; Hart, S. R.; Dunham, R.

    2006-12-01

    The thickest beds of hydrothermal manganese oxides recovered to date from the global ocean were collected from a volcanic cone in the south Pacific. In April 2005, samples were dredged aboard the R.V. Kilo Moana from a volcanic cone on the lower flank of Tulaga seamount (about 2,700 m water depth; 14° 39.222' S; 170° 1.730' W), located 115 km SW of Vailulu'u, the volcanically and hydrothermally active center of the Samoan hotspot. Additional hydrothermal manganese samples were collected off Ofu Island (dredge Alia 107), 72 km to the WSW of Vailulu'u. Manganese-oxide beds up to 9 cm thick are composed of birnessite and 10 Å manganates. Some layers consist of Mn-oxide columnar structures 4 cm long and 1 cm wide, which have not been described previously. The mean Mn and Fe contents of 18 samples are 51 weight percent and 0.76 weight percent, respectively. Elevated concentrations of Li (mean 0.11 wt. percent) are indicators of a hydrothermal origin, and distinguishes these samples, along with the high Mn and low Fe contents, from hydrogenetic Fe-Mn crusts. Other enriched elements include Ba (mean 0.14 percent), Cu (249 ppm), Mo (451 ppm), Ni (400 ppm), Zn (394 ppm), V (214 ppm), and W (132 ppm). Chondrite-normalized REE patterns show large negative Ce anomalies and LREE enrichments, both characteristic of hydrothermal Mn deposits. Small negative Eu anomalies are not typical of hydrothermal deposits and can be explained either by the absence of leaching of plagioclase by the hydrothermal fluids or by the precipitation of Eu-rich minerals, such as barite and anhydrite, at depth. The high base-metal contents indicate that sulfides are not forming deeper in the hydrothermal system or that such deposits are being leached by the ascending fluids. Textures of the thickest Mn deposits indicate that the Mn oxides formed below the seabed from ascending fluids during multiple phases of waxing and waning hydrothermal pulses. The deposits were later exposed at the seafloor by

  1. Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

    Science.gov (United States)

    Guo, Qinghai; Kirk Nordstrom, D.; Blaine McCleskey, R.

    2014-11-01

    Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1-2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

  2. Quantitative simulation of the hydrothermal systems of crystallizing magmas on the basis of transport theory and oxygen isotope data: an analysis of the Skaergaard intrusion

    Energy Technology Data Exchange (ETDEWEB)

    Norton, D. (Univ. of Arizona, Tucson); Taylor, H.P. Jr.

    1979-08-01

    Application of the principles of transport theory to studies of magma-hydrothermal systems permits quantitative predictions to be made of the consequences of magma intruding into permeable rocks. Transport processes which redistribute energy, mass, and momentum in these environments can be represented by a set of partial differential equations involving the rate of change of extensive properties in the system. Numerical approximation and computer evaluation of the transport equations effectively simulate the crystallization of magma, cooling of the igneous rocks, advection of chemical components, and chemical and isotopic mass transfer between minerals and aqueous solution. Numerical modeling of the deep portions of the Skaergaard magma-hydrothermal system has produced detailed maps of the temperature, pressure, fluid velocity, integrated fluid flux, delta/sup 18/O-values in rock and fluid, and extent of nonequilibrium exchange reactions between fluid and rock as a function of time for a two-dimensional cross-section through the pluton. An excellent match was made between calculated delta/sup 18/O-values and the measured delta/sup 18/O-values in the three principal rock units, basalt, gabbro, and gneiss, as well as in xenoliths of roof rocks that are now embedded in Layered Series; the latter were evidently depleted in /sup 18/O early in the system's cooling history, prior to falling to the bottom of the magma chamber. The best match was realized for a system in which the bulk rock permeabilities were 10/sup -13/ cm/sup 2/ for the intrusion, 10/sup 11/ cm/sup 2/ for basalt, and 10/sup -16/ cm/sup 2/ for gneiss; reaction domain sizes were 0.2 cm in the intrusion and gneiss and 0.01 cm in the basalts, and activation energy for the isotope exchange reaction between fluid and plagioclase was 30 kcal/ mole.

  3. 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

    Science.gov (United States)

    Xu, G.; Bemis, K. G.

    2014-12-01

    theories to estimate the crustal permeability, a fundamental property of subsurface hydrothermal circulation, from the phase shift of the tidal oscillations of venting temperature relative to ambient ocean tides. These results together shed light on the influences of seismic and oceanic processes on a seafloor hydrothermal system.

  4. Petrology and Geochemistry of Hydrothermally Altered Volcanic Rocks in the Iheya North Hydrothermal Field, Middle Okinawa Trough

    Science.gov (United States)

    Yamasaki, T.

    2015-12-01

    The Iheya North hydrothermal field is located in the middle Okinawa Trough, a young and actively spreading back-arc basin extending behind the Ryukyu arc-trench system in the southeastern margin of the East China Sea. In this hydrothermal field, two scientific drilling expeditions (IODP Exp 331 and SIP CK14-04) were conducted using a deep-sea drilling vessel "Chikyu," and samples from a total of 27 holes were taken. Through these expeditions, Kuroko-type volcanogenic massive sulfide deposits (VMS), hydrothermally altered volcanic rocks, and pumiceous and pelagic sediments were recovered. The recovered core provided important information about the relationship between hydrothermal activity, alteration, and ore mineralization. Whole-rock major element composition and trace element (TE) patterns of pumices were very similar to those of rhyolites in the middle Okinawa Trough (RMO). However, pumices were relatively enriched in chalcophile elements Sr and Nb, which suggest incipient mineralization. Volcanic rock generally demonstrated strong silicification and was greenish pale gray in color. Regardless of severe alteration, some rock displayed major element composition broadly similar to the RMO. Alteration was evidenced by an increase in the content of SiO2 and MgO, and decrease in Al2O3, Na2O, and K2O content. The most striking geochemical feature of altered volcanic rock was the discordance between texture and the degree of modification of TEs. Some samples showed decussate texture occupied by petal-like quartz with severe silicification, but no prominent disturbance of concentration and patterns of TEs were observed. In contrast, samples with well-preserved igneous porphyritic texture showed very low TE content and modification of TE patterns. These results suggest that the modification of texture and composition of TEs, as well as silicification, do not occur by a uniform process, but several processes. This may reflect the differences in temperature and the

  5. Evolving patterns of the fluids within the TAG hydrothermal field

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The mixing of seawater/hydrothermal fluid within the large seafloor hydrothermal sulfide deposits plays a key role in the formation processes of the sulfide deposits.Some issues attract considerable attentions in the study of seafloor hydrothermal system in recent years,such as the relationships among different types of vent fluids,the characteristics of chemical compositions and mineral assemblages of the hydrothermal deposits and their governing factors.Combined with the measured data of hydrothermal fluid in the TAG field,the thermodynamic model of mixing processes of the heated seawater at different temperatures and the hydrothermal fluid is calculated to understand the precipitation mechanism of anhydrite and the genetic relationships between the black and white smoker fluids within the TAG mound.The results indicate that the heating of seawater and the mixing of hydrothermal fluid/seawater are largely responsible for anhydrite precipitation and the temperature of the heated seawater is not higher than 150 ℃ and the temperature of the end-member hydrothermal fluid is not lower than 400℃.Based on the simulated results,the evolving patterns of fluids within the TAG deposit are discussed.The mixed fluid of the end-member hydrothermal fluid and the seawater heated by wall rock undergoes conductive cooling during upflowing within the deposit and forms "White Smoker" eventually.In addition,the end-member hydrothermal fluid without mixed with seawater,but undergoing conductive cooling,vents out of the deposit and forms "Black Smoker".

  6. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Rudolf, Andreas

    2011-01-01

    This article reviews the hydrothermal liquefaction of biomass with the aim of describing the current status of the technology. Hydrothermal liquefaction is a medium-temperature, high-pressure thermochemical process, which produces a liquid product, often called bio-oil or bi-crude. During...... the hydrothermal liquefaction process, the macromolecules of the biomass are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed...... by dehydration or decarboxylation. The chemical properties of bio-oil are highly dependent of the biomass substrate composition. Biomass constitutes of various components such as protein; carbohydrates, lignin and fat, and each of them produce distinct spectra of compounds during hydrothermal liquefaction...

  7. Mode I fracture toughness behavior of hydro-thermally aged carbon fibre reinforced DGEBA-HHPA-PES systems

    Science.gov (United States)

    Alessi, Sabina; Pitarresi, Giuseppe; Spadaro, Giuseppe; Tumino, Davide

    2012-07-01

    In this work the Mode I fracture toughness behavior of unidirectional CFRP laminates is investigated by means of Double Cantilever Beam (DCB) tests. The composite samples were manufactured by thermal curing after impregnation of a Carbon fabric with a DGEBA epoxy and anhydride HHPA curing agent. One resin batch was also mixed with a PES thermoplastic monomer to enhance the matrix toughness. Two lots of samples, toughened and untoughened, were then left to soak in hot water to achieve various degrees of aging. The influence of matrix toughening and hydrothermal aging on the delamination behavior of the composite have then been assessed and correlated with characterization data from Dynamic Mechanical Thermal Analysis (DMTA) and Scanning Electron Microscopy (SEM).

  8. On the feature of seafloor hydrothermal systems' evolutionary and its mineralization in Mid-Ocean Ridge%大洋中脊海底热液系统的演化特征及其成矿意义

    Institute of Scientific and Technical Information of China (English)

    刘为勇; 郑连福; 陶春辉; 李怀明; 窦炳琚

    2011-01-01

    Seafloor hydrothermal activity in Mid-Ocean Ridge has become one of hotspots in geosciences because of its valuable scientific researching significance. Hydrothermal systems at seafloor spreading centers are characterized by a complex interplay among magmatic, tectonic and biogeochemical processes linked by fluid circulation and heat transfer in the oceanic crust. It could be divided into three phases on the evolution of magma-controlled hydrothermal system, an initial phase, a living phase and a dying phase. The three phases simply reflects the evolution mechanism of hydrothermal system. On the basis of previous data collecting and studies, the authors consider that there are three corresponding hydrothermal activity phases at fast spreading centers, and they evolved with shorter phases, no more than ten years or decades. Although magmatic budget is not so robust at slow spreading centers, the characteristics of each phases are not obvious, and hydrothermal system with universal heat and special structure could continue more than ten thousand years or evolve with tens of thousand years episodically. So the authors affirm that hydrothermal processes are controlled by heat supply and tectonic conditions, such as Rainbow and TAG hydrothermal field in Mid Atlantic Ridge, or even Middle Valley hydrothermal field in Juan de Fuca Ridge, they all have experienced a long-term evolution caused by their sufficient heat supply and favorable superior tectonic conditions. Uncovered ultramafic rock and deeper extension brittle failure are common existent at ultra-slow spreading centers. It has been detected higher incidence of hydrothermal venting than calculated by Magmatic Budget Hypothesis in recent decades, such as Gakkel Ridge in the Arctic Ocean and Southwest Indian Ridge, certain segments areas with extra irregular heat supply and more favorable superior tectonic conditions may cause huge hydrotherrnal sulfide deposit by long-term cumulating. China have made great

  9. 中国热液铀矿成矿理论体系%On the theory system of hydrothermal uranium metalization in China

    Institute of Scientific and Technical Information of China (English)

    杜乐天

    2011-01-01

    在总结前人大量研究成果的基础上,笔者尝试对我国的热液铀矿成矿理论体系作一简要概括.在成矿的"源-运-导-集-存"基本规律问题上,此体系大体包含以下10个方面:(1)硅化带成矿类型;(2)矿-岩时差;(3)碱交代作用;(4)成矿壳层;(5)4种铀矿类型(花岗岩型、火山岩型、碳硅泥岩型、砂岩型)统一构造-热液成矿;(6)铀成矿预富集序列;(7)花岗岩岩浆演化链的解耦;(8)绢英岩化高温富矿类型;(9)玄武岩事件;(10)幔汁成岩成矿论.%Based on summarizing the mass of research outcome of the predecessors, the author attempts to make a brief generalization on the theory system of hydrothermal uranium mineralization in China. The system of uranium metalization is founded in the basic way of uranium source-migration-transportation-richment-reservation. The system mainly consists of the following frames: (1) mineralization type of silification zone; (2) age gap of mineralization to host rock; (3) alkli metasomatism; (4) metallogenic layer of crust; (5) integratation of 4 types mineralization (granite, volcanics, carbonaceous-siliceous-argilaceous rock and sandstone) in tectonic-hydrothermal process; (6) pre-enrichment process of metallization; (7) decouplement of granite magma evolution; (8) types of rich ore by high tempreture sericitization; (9) basalt event; (10) rock and ore formation by HARCON.

  10. Hydrothermal Processes in the Archean - New Insights from Imaging Spectroscopy

    NARCIS (Netherlands)

    Ruitenbeek, F.J.A. van

    2007-01-01

    The aim of this research was to gain new insights in fossil hydrothermal systems using airborne imaging spectroscopy. Fossil submarine hydrothermal systems in Archean greenstone belts and other geologic terranes are important because of their relationship with volcanic massive sulfide (VMS) mineral

  11. Hydrothermal Processes in the Archean - New Insights from Imaging Spectroscopy

    NARCIS (Netherlands)

    Ruitenbeek, F.J.A. van

    2007-01-01

    The aim of this research was to gain new insights in fossil hydrothermal systems using airborne imaging spectroscopy. Fossil submarine hydrothermal systems in Archean greenstone belts and other geologic terranes are important because of their relationship with volcanic massive sulfide (VMS) mineral

  12. Hydrothermal cooling of the ocean crust: Insights from ODP Hole 1256D

    Science.gov (United States)

    Harris, Michelle; Coggon, Rosalind M.; Wood, Martin; Smith-Duque, Christopher E.; Henstock, Timothy J.; Teagle, Damon A. H.

    2017-03-01

    The formation of new ocean crust at mid-ocean ridges is a fundamental component of the plate tectonic cycle and involves substantial transfer of heat and mass from the mantle. Hydrothermal circulation at mid-ocean ridges is critical for the advection of latent and sensible heat from the lower crust to enable the solidification of ocean crust near to the ridge axis. The sheeted dike complex (SDC) is the critical region between the eruptive lavas and the gabbros through which seawater-derived recharge fluids must transit to exchange heat with the magma chambers that form the lower ocean crust. ODP Hole 1256D in the eastern equatorial Pacific Ocean provides the only continuous sampling of in-situ intact upper ocean crust formed at a fast spreading rate, through the SDC into the dike-gabbro transition zone. Here we exploit a high sample density profile of the Sr-isotopic composition of Hole 1256D to quantify the time-integrated hydrothermal recharge fluid flux through the SDC. Assuming kinetically limited fluid-rock Sr exchange, a fluid flux of 1.5- 3.2 ×106 kgm-2 is required to produce the observed Sr-isotopic shifts. Despite significant differences in the distribution and intensity of hydrothermal alteration and fluid/rock Sr-isotopic exchange between Hole 1256D and SDC sampled in other oceanic environments (ODP Hole 504B, Hess Deep and Pito Deep), the estimated recharge fluid fluxes at all sites are similar, suggesting that the heat flux extracted by the upper crustal axial hydrothermal system is relatively uniform at intermediate to fast spreading rates. The hydrothermal heat flux removed by fluid flow through the SDCs, is sufficient to remove only ∼20 to 60% of the available latent and sensible heat from the lower crust. Consequently, there must be additional thermal and chemical fluid-rock exchange deeper in the crust, at least of comparable size to the upper crustal hydrothermal system. Two scenarios are proposed for the potential geometry of this deeper

  13. Hydrothermal pretreatment of palm oil empty fruit bunch

    Science.gov (United States)

    Simanungkalit, Sabar Pangihutan; Mansur, Dieni; Nurhakim, Boby; Agustin, Astrid; Rinaldi, Nino; Muryanto, Fitriady, Muhammad Ariffudin

    2017-01-01

    Hydrothermal pretreatment methods in 2nd generation bioethanol production more profitable to be developed, since the conventional pretreatment, by using acids or alkalis, is associated with the serious economic and environmental constraints. The current studies investigate hydrothermal pretreatment of palm oil empty fruit bunch (EFB) in a batch tube reactor system with temperature and time range from 160 to 240 C and 15 to 30 min, respectively. The EFB were grinded and separated into 3 different particles sizes i.e. 10 mesh, 18 mesh and 40 mesh, prior to hydrothermal pretreatment. Solid yield and pH of the treated EFB slurries changed over treatment severities. The chemical composition of EFB was greatly affected by the hydrothermal pretreatment especially hemicellulose which decreased at higher severity factor as determined by HPLC. Both partial removal of hemicellulose and migration of lignin during hydrothermal pretreatment caused negatively affect for enzymatic hydrolysis. This studies provided important factors for maximizing hydrothermal pretreatment of EFB.

  14. Stabilization and oxidation kinetics of iron in hydrothermal plumes above the East Scotia Ridge

    Science.gov (United States)

    Hawkes, J.; Connelly, D.; Achterberg, E. P.

    2011-12-01

    Two hydrothermal vent fields were recently discovered along the East Scotia Ridge (a back arc basin spreading centre) in the Southern Ocean. These are the most southerly high-temperature vents discovered to date. End-member fluids and the associated hydrothermal plumes were sampled for total, dissolved and 'soluble' (cathodic stripping voltammetry (CLE-CSV) experiments. In doing so, we present a first evaluation of the relationship between ligand and colloid stabilization mechanisms in hydrothermal plume settings. Plume samples are discussed in relation to the end-member fluid chemistry of the vent fields, which have relatively low dissolved metal concentrations (~1 mM Fe) and very high H2S:Fe ratios (~8) compared with typical mid-ocean ridge settings. The bottom water oxygen concentration is 175 μM (c.f. North Atlantic: 250 μM, North Pacific: 104 μM), and background dissolved organic carbon (DOC) concentrations are ~43 μM. Ambient seawater temperature at plume depth (~2200m) is close to 0°C. All of these features may play a part in the observed Fe(II) oxidation kinetics and Fe(III) stabilization and therefore the impact of hydrothermal Fe input on Southern Ocean biogeochemistry. The likelihood of long range transport of dissolved iron from this type of high-temperature hydrothermal system will be discussed.

  15. Diffuse flow environments within basalt- and sediment-based hydrothermal vent ecosystems harbor specialized microbial communities.

    Science.gov (United States)

    Campbell, Barbara J; Polson, Shawn W; Zeigler Allen, Lisa; Williamson, Shannon J; Lee, Charles K; Wommack, K Eric; Cary, S Craig

    2013-01-01

    Hydrothermal vents differ both in surface input and subsurface geochemistry. The effects of these differences on their microbial communities are not clear. Here, we investigated both alpha and beta diversity of diffuse flow-associated microbial communities emanating from vents at a basalt-based hydrothermal system along the East Pacific Rise (EPR) and a sediment-based hydrothermal system, Guaymas Basin. Both Bacteria and Archaea were targeted using high throughput 16S rRNA gene pyrosequencing analyses. A unique aspect of this study was the use of a universal set of 16S rRNA gene primers to characterize total and diffuse flow-specific microbial communities from varied deep-sea hydrothermal environments. Both surrounding seawater and diffuse flow water samples contained large numbers of Marine Group I (MGI) Thaumarchaea and Gammaproteobacteria taxa previously observed in deep-sea systems. However, these taxa were geographically distinct and segregated according to type of spreading center. Diffuse flow microbial community profiles were highly differentiated. In particular, EPR dominant diffuse flow taxa were most closely associated with chemolithoautotrophs, and off axis water was dominated by heterotrophic-related taxa, whereas the opposite was true for Guaymas Basin. The diversity and richness of diffuse flow-specific microbial communities were strongly correlated to the relative abundance of Epsilonproteobacteria, proximity to macrofauna, and hydrothermal system type. Archaeal diversity was higher than or equivalent to bacterial diversity in about one third of the samples. Most diffuse flow-specific communities were dominated by OTUs associated with Epsilonproteobacteria, but many of the Guaymas Basin diffuse flow samples were dominated by either OTUs within the Planctomycetes or hyperthermophilic Archaea. This study emphasizes the unique microbial communities associated with geochemically and geographically distinct hydrothermal diffuse flow environments.

  16. Pension System Related Public Politics

    Directory of Open Access Journals (Sweden)

    LIVIU RADU

    2015-05-01

    Full Text Available This paper aims to find some answers regarding the long term sustainability of the pension system. Romania’s pension system originates from the invalidity insurances and pension system designed by the German cancellor Otto Eduard Leopold von Bismark in 1889. From a European perspective, Romania has to fill an obvious gap regarding the reformation of the national public pension system. International experience, particularly of the last 130 years, indicates that, in actuality, multiple pension systems have been put into function in most of the world’s countries and which are diferenciated by some elements (organizing and managing the system, defyning pension rights, method of forming the resources, the pension’s level rapported to the average income etc. and after the eficacity degree dependent on internal influences, social, economic and demographic environment, and last but not least by the political factor.

  17. Spatial Distribution of b-value of the Copahue volcano during 2012-2014 eruptive period: Relationship between magmatic and hydrothermal system

    Science.gov (United States)

    Lazo, Jonathan; Basualto, Daniel; Bengoa, Cintia; Cardona, Carlos; Franco, Luis; Gil-Cruz, Fernando; Hernández, Erasmo; Lara, Luis; Lundgren, Paul; Medina, Roxana; Morales, Sergio; Peña, Paola; Quijada, Jonathan; Samsonov, Sergey; San Martin, Juan; Valderrama, Oscar

    2015-04-01

    Temporal and spatial variations of b-value have been interpreted as regional stress changes on active tectonic zones or magma ascent and/or hydrothermal fluids mobilization that could affect to active volcanic arc. Increasing of fluids pressure, medium heterogeneities or temperature changes would be the cause of these variations. The Copahue volcano is a shield strato-volcano that has been edified on the western margin of the Caviahue Caldera, located in the international border between Chile and Argentina, which contain an important geothermic field and is located at a horse-tail structure of the Liquiñe-Ofqui Fault Zone. The pre-fracture nature of its basement, as well as an extensive geothermic field, would be producing very complex conditions to fluids movement that could be exploring to use the 'b' value of the recorded seismicity between 2012 and 2014. Based in the database of VT seismic events, we used 2.073 events to calculate the b-value to obtain the 2D and 3D distribution maps. Results showed two anomalous zones: the first one located 9 Km to NE of the active crater, 3-6 Km depth, with high b-values (>1.2) that is associated with a very high production rate of small earthquakes that could suggest a brittle zone, located in the active geothermal field. The second zone, showed a low b-values (~ 0.7), located to east of the volcano edifice at geothermal system, the b-value offers a tool to understand the distribution of the seismic sources and hence a physical constrain for the coupled magmatic/hydrothermal system.

  18. The thermal and chemical evolution of hydrothermal vent fluids in shale hosted massive sulphide (SHMS) systems from the MacMillan Pass district (Yukon, Canada)

    Science.gov (United States)

    Magnall, J. M.; Gleeson, S. A.; Blamey, N. J. F.; Paradis, S.; Luo, Y.

    2016-11-01

    At Macmillan Pass (YT, Canada), the hydrothermal vent complexes beneath two shale-hosted massive sulphide (SHMS) deposits (Tom, Jason) are well preserved within Late Devonian strata. These deposits provide a unique opportunity to constrain key geochemical parameters (temperature, salinity, pH, fO2, ΣS) that are critical for metal transport and deposition in SHMS systems, and to evaluate the interaction between hydrothermal fluids and the mudstone host rock. This has been achieved using a combination of detailed petrography, isotopic techniques (δ34S, δ13C and δ18O values), carbonate rare earth element analysis (LA-ICP-MS), fluid inclusion analysis (microthermometry, gas analysis via incremental crush fast scan mass spectrometry), and thermodynamic modelling. Two main paragenetic stages are preserved in both vent complexes: Stage 1 comprises pervasive ankerite alteration of the organic-rich mudstone host rock and crosscutting stockwork ankerite veining (±pyrobitumen, pyrite and quartz) and; Stage 2 consists of main stage massive sulphide (galena-pyrrhotite-pyrite ± chalcopyrite-sphalerite) and siderite (±quartz and barytocalcite) mineralisation. Co-variation of δ18O and δ13C values in ankerite can be described by temperature dependent fractionation and fluid rock interaction. Together with fluid inclusion microthermometry, this provides evidence of a steep thermal gradient (from 300 to ∼100 °C) over approximately 15 m stratigraphic depth, temporally and spatially constrained within the paragenesis of both vent complexes and developed under shallow lithostatic (28), characteristic of diagenetic fluids, are coupled with positive europium anomalies and variable light REE depletion, which are more consistent with chloride complexation in hot (>250 °C) hydrothermal fluids. In this shallow sub-seafloor setting, thermal alteration of organic carbon in the immature, chemically reactive mudstones also had an important role in the evolution of fluid chemistry

  19. A data processing method for MAPR hydrothermal plume tur-bidity data and its application in the Precious Stone Mountain hydrothermal field

    Institute of Scientific and Technical Information of China (English)

    CHEN Sheng; TAO Chunhui; LI Huaiming; CHEN Yongshun; ZHOU Jianping; WU Tao

    2014-01-01

    Hydrothermal plume is an important constituent of seabed hydrothermal circulation and is also one of the characteristics of active hydrothermal vents. Portable Miniature Autonomous Plume Recorders (MAPR) attached to a towed deep-sea instrument was used to search for hydrothermal plumes and hydrothermal vents. We introduced the basic principle of MAPR based on deep towing technology to detect plumes, then analyzed the factors affecting the quality of the MAPR data and presented a data correction method for MAPR, including instrument location correction, noise reduction processing, system error elimination and seawater background reduction. Finally we applied the method to analyze MAPR data obtained during the Chinese DY115-21 cruise on R/VDayang Iin the “Precious Stone Mountain” hydrothermal field on the Gala-pagos Microplate. The results provided a better understanding of the distribution of the hydrothermal activ-ity in this field, indicating the presence of a new hydrothermal vent.

  20. Hydrothermal replacement of biogenic and abiogenic aragonite by Mg-carbonates - Relation between textural control on effective element fluxes and resulting carbonate phase

    Science.gov (United States)

    Jonas, Laura; Müller, Thomas; Dohmen, Ralf; Immenhauser, Adrian; Putlitz, Benita

    2017-01-01

    Dolomitization, i.e., the secondary replacement of calcite or aragonite (CaCO3) by dolomite (CaMg[CO3]2), is one of the most volumetrically important carbonate diagenetic processes. It occurs under near surface and shallow burial conditions and can significantly modify rock properties through changes in porosity and permeability. Dolomitization fronts are directly coupled to fluid pathways, which may be related to the initial porosity/permeability of the precursor limestone, an existing fault network or secondary porosity/permeability created through the replacement reaction. In this study, the textural control on the replacement of biogenic and abiogenic aragonite by Mg-carbonates, that are typical precursor phases in the dolomitization process, was experimentally studied under hydrothermal conditions. Aragonite samples with different textural and microstructural properties exhibiting a compact (inorganic aragonite single crystal), an intermediate (bivalve shell of Arctica islandica) and open porous structure (skeleton of coral Porites sp.) were reacted with a solution of 0.9 M MgCl2 and 0.015 M SrCl2 at 200 °C. The replacement of aragonite by a Ca-bearing magnesite and a Mg-Ca carbonate of non-stoichiometric dolomitic composition takes place via a dissolution-precipitation process and leads to the formation of a porous reaction front that progressively replaces the aragonite precursor. The reaction leads to the development of porosity within the reaction front and distinctive microstructures such as gaps and cavities at the reaction interface. The newly formed reaction rim consists of chemically distinct phases separated by sharp boundaries. It was found that the number of phases and their chemical variation decreases with increasing initial porosity and reactive surface area. This observation is explained by variations in effective element fluxes that result in differential chemical gradients in the fluid within the pore space of the reaction rim. Observed

  1. Intersection Types and Related Systems

    Directory of Open Access Journals (Sweden)

    Paweł Parys

    2017-02-01

    Full Text Available We present a new approach to the following meta-problem: given a quantitative property of trees, design a type system such that the desired property for the tree generated by an infinitary ground lambda-term corresponds to some property of a derivation of a type for this lambda-term, in this type system. Our approach is presented in the particular case of the language finiteness problem for nondeterministic higher-order recursion schemes (HORSes: given a nondeterministic HORS, decide whether the set of all finite trees generated by this HORS is finite. We give a type system such that the HORS can generate a tree of an arbitrarily large finite size if and only if in the type system we can obtain derivations that are arbitrarily large, in an appropriate sense; the latter condition can be easily decided.

  2. Chemical reaction path modeling of hydrothermal processes on Mars: Preliminary results

    Science.gov (United States)

    Plumlee, Geoffrey S.; Ridley, W. Ian

    1992-01-01

    Hydrothermal processes are thought to have had significant roles in the development of surficial mineralogies and morphological features on Mars. For example, a significant proportion of the Martian soil could consist of the erosional products of hydrothermally altered impact melt sheets. In this model, impact-driven, vapor-dominated hydrothermal systems hydrothermally altered the surrounding rocks and transported volatiles such as S and Cl to the surface. Further support for impact-driven hydrothermal alteration on Mars was provided by studies of the Ries crater, Germany, where suevite deposits were extensively altered to montmorillonite clays by inferred low-temperature (100-130 C) hydrothermal fluids. It was also suggested that surface outflow from both impact-driven and volcano-driven hydrothermal systems could generate the valley networks, thereby eliminating the need for an early warm wet climate. We use computer-driven chemical reaction path calculation to model chemical processes which were likely associated with postulated Martian hydrothermal systems.

  3. Catalytic Hydrothermal Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  4. Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Qinfu [Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Wang Tianyi [Department of Clinical Pharmacy, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Wang Jing [Department of Physical Chemistry, School of Basic Science, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Zheng Li; Jiang, Tongying; Cheng Gang [Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Wang Siling, E-mail: silingwang@syphu.edu.cn [Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China)

    2011-09-15

    In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N{sub 2} adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.

  5. Hydrothermal carbonization of anaerobically digested maize silage.

    Science.gov (United States)

    Mumme, Jan; Eckervogt, Lion; Pielert, Judith; Diakité, Mamadou; Rupp, Fabian; Kern, Jürgen

    2011-10-01

    Hydrochars were prepared by hydrothermal carbonization (HTC) of maize silage previously treated at 55 °C in a two-stage solid-state reactor system. The HTC was carried out in a 1-L stirred pressure reactor with pH regulation by citric acid. The treated silage carbonized at relatively mild conditions (190 °C, 2 h), and the hydrochars showed mainly amorphous macro-size features with a carbon content of 59-79% (ash-free, dry) and a higher heating value of 25-36 MJ kg⁻¹. Temperature was the main influencing factor. The surface area according to Brunauer-Emmett-Teller (BET) analysis was highest at 190 °C (12.3 m²) g⁻¹). Based on these results, the hydrochars are potentially interesting for applications such as an alternative fuel or a soil conditioner.

  6. Heat and mass flux estimation of modern seafloor hydrothermal activity

    Institute of Scientific and Technical Information of China (English)

    ZHAI Shikui; WANG Xingtao; YU Zenghui

    2006-01-01

    Research on heat and mass flux yielded by modern seafloor hydrothermal activity is very important, because it is involved not only in the base of ocean environment research, but also in the historical evolution of seawater properties. Currently, estimating heat flux is based on the observation data of hydrothermal smokers, low-temperature diffusive flow and mid-ocean ridge mainly. But there are some faults, for example, there is lack of a concurrent conductive item in estimating the heat flux by smokers and the error between the half-space cooling model and the observation data is too large. So, three kinds of methods are applied to re-estimating the heat flux of hydrothermal activity resepectively, corresponding estimation is 97.359 GW by hydrothermal smoker and diffusive flow, 84.895 GW by hydrothermal plume, and 4.11 TW by exponential attenuation method put forward by this paper. Research on mass flux estimation is relatively rare, the main reason for this is insufficient field observation data. Mass fluxes of different elements are calculated using hydrothermal vent fluid data from the TAG hydrothermal area on the Mid-Atlantic Ridge for the first time. Difference of estimations by different methods reflects the researching extent of hydrothermal activity, and systematically in-situ observation will help to estimate the contribution of hydrothermal activity to ocean chemical environment, ocean circulation and global climate precisely.

  7. A hydrogeological conceptual model of the Suio hydrothermal area (central Italy)

    Science.gov (United States)

    Saroli, Michele; Lancia, Michele; Albano, Matteo; Casale, Anna; Giovinco, Gaspare; Petitta, Marco; Zarlenga, Francesco; dell'Isola, Marco

    2017-09-01

    A hydrogeological conceptual model has been developed that describes the hydrothermal system of Suio Terme (central Italy). The studied area is located along the peri-Tyrrhenian zone of the central Apennines, between the Mesozoic and Cenozoic carbonate platform sequences of the Aurunci Mountains and the volcanic sequences of the Roccamonfina. A multi-disciplinary approach was followed, using new hydrogeological surveys, the interpretation of stratigraphic logs of boreholes and water wells, and geophysical data—seismic sections, shear-wave velocity (Vs) crustal model and gravimetric model. The collected information allowed for construction of a conceptual hydrogeological model and characterization of the hydrothermal system. The Suio hydrothermal system is strongly influenced by the Eastern Aurunci hydrostructure. Along the southeastern side, the top of the hydrostructure sinks to -1,000 m relative to sea level via a series of normal faults which give origin to the Garigliano graben. Geological and hydrogeological data strongly suggest the propagation and mixing of hot fluids, with cold waters coming from the shallow karst circuit. The aquitard distribution, the normal tectonic displacements and the fracturing of the karst hydrostructure strongly influence the hydrothermal basin. Carbon dioxide and other gasses play a key role in the whole circuit, facilitating the development of the hydrothermal system. The current level of knowledge suggests that the origin of the Suio hydrothermalism is the result of interaction between the carbonate reservoir of the Eastern Aurunci Mountains and the hot and deep crust of this peri-Tyrrhenian sector, where the Roccamonfina volcano represents the shallowest expression.

  8. A hydrogeological conceptual model of the Suio hydrothermal area (central Italy)

    Science.gov (United States)

    Saroli, Michele; Lancia, Michele; Albano, Matteo; Casale, Anna; Giovinco, Gaspare; Petitta, Marco; Zarlenga, Francesco; dell'Isola, Marco

    2017-03-01

    A hydrogeological conceptual model has been developed that describes the hydrothermal system of Suio Terme (central Italy). The studied area is located along the peri-Tyrrhenian zone of the central Apennines, between the Mesozoic and Cenozoic carbonate platform sequences of the Aurunci Mountains and the volcanic sequences of the Roccamonfina. A multi-disciplinary approach was followed, using new hydrogeological surveys, the interpretation of stratigraphic logs of boreholes and water wells, and geophysical data—seismic sections, shear-wave velocity (Vs) crustal model and gravimetric model. The collected information allowed for construction of a conceptual hydrogeological model and characterization of the hydrothermal system. The Suio hydrothermal system is strongly influenced by the Eastern Aurunci hydrostructure. Along the southeastern side, the top of the hydrostructure sinks to -1,000 m relative to sea level via a series of normal faults which give origin to the Garigliano graben. Geological and hydrogeological data strongly suggest the propagation and mixing of hot fluids, with cold waters coming from the shallow karst circuit. The aquitard distribution, the normal tectonic displacements and the fracturing of the karst hydrostructure strongly influence the hydrothermal basin. Carbon dioxide and other gasses play a key role in the whole circuit, facilitating the development of the hydrothermal system. The current level of knowledge suggests that the origin of the Suio hydrothermalism is the result of interaction between the carbonate reservoir of the Eastern Aurunci Mountains and the hot and deep crust of this peri-Tyrrhenian sector, where the Roccamonfina volcano represents the shallowest expression.

  9. Sm-Nd age of the fazenda brasileiro gabbro, Bahia, Brazil: example of robust behavior of the Sm-Nd isotopic system under extreme hydrothermal alteration

    Directory of Open Access Journals (Sweden)

    Márcio M. Pimentel

    2003-09-01

    Full Text Available The Fazenda Brasileiro gold mineralization is hosted by a gabbroic sill, intrusive into metavolcanicmetasedimentary rocks of the Rio Itapicuru Greenstone Belt, São Francisco Craton. The 2.05 Ga old mineralization is associated with intense shearing and hydrothermal alteration, and the host gabbro is altered to a series of rocks rich in sericite, chlorite, actinolite, carbonate and quartz. Twelve whole-rock samples of the gold mineralization, representing varied degrees of alteration, from rocks with preserved igneous textures to the ore (quartz-carbonate-sulfide-chlorite, were studied by the Sm-Nd method. All analytical points resulted in an isochron (MSWD = 1.9 indicating the age of 2142 +/- 47 Ma (1s and Epsilon Nd (T of +1.2. Chlorite-sericite-carbonate rich hydrothermal rocks indicate the age of 2148 +/- 57 Ma and Epsilon Nd (T of +1.1. The positive Epsilon Nd (T suggest limited or no contamination with older continental crust, compatible with an oceanic setting for the tholeiites. Combined withREEdata, the Sm-Nd isotopic results reveal that the hydrothermal alteration, although intense, was unable to alter significantly the Sm/Nd ratios of the original igneous rocks and did not cause important scatter of the analytical points, providing a rare example of robust behavior of the isotopic system, even under intense hydrothermal alteration.A mineralização de ouro de Fazenda Brasileiro é hospedada por um sill gabróico intrusivo em rochas metavulcânicas/metassedimentares do Greenstone Belt do Rio Itapicuru, Craton do São Francisco. A mineralização, com idade de ca. 2.05 Ga, está associada com forte cizalhamento e alteração hidrotermal, e o gabro hospedeiro está alterado para rochas ricas em clorita, actinolita, carbonato e quartzo. Doze amostras de rocha total representando graus variados de alteração hidrotermal, desde rochas com texturas ígneas reliquiares até o minério (quartzo-carbonato-sulfeto-clorita, foram estudadas pelo

  10. Selected data for hydrothermal-convection systems in the United States with estimated temperatures greater than or equal to 90/sup 0/C: back-up data for US Geological Survey Circular 790

    Energy Technology Data Exchange (ETDEWEB)

    Mariner, R.H.; Brook, C.A.; Swanson, J.R.; Mabey, D.R.

    1978-12-01

    A compilation of data used in determining the accessible resource base for identified hydrothermal convection systems greater than or equal to 90/sup 0/C in the United States are presented. Geographic, geologic, chemical, isotopic, volumetric, and bibliographic data and calculated thermal energy contents are listed for all vapor-dominated and hot-water systems with estimated reservoir temperatures greater than or equal to 90/sup 0/C and reservoir depths less than 3 km known to the authors in mid 1978. Data presented here is stored in the US Geological Survey's geothermal computer file GEOTHERM. Data for individual hydrothermal convection systems in each state are arranged geographically from north to south and west to east without regard to the type or temperature of the system. Locations of the systems and corresponding reference numbers are shown on map 1 accompanying US Geological Survey Circular 790.

  11. Complexing and hydrothermal ore deposition

    CERN Document Server

    Helgeson, Harold C

    1964-01-01

    Complexing and Hydrothermal Ore Deposition provides a synthesis of fact, theory, and interpretative speculation on hydrothermal ore-forming solutions. This book summarizes information and theory of the internal chemistry of aqueous electrolyte solutions accumulated in previous years. The scope of the discussion is limited to those aspects of particular interest to the geologist working on the problem of hydrothermal ore genesis. Wherever feasible, fundamental principles are reviewed. Portions of this text are devoted to calculations of specific hydrothermal equilibriums in multicompone

  12. Geochemical Evidence for Recent Hydrothermal Alteration of Marine Sediments in Mid-Okinawa Trough, Southwest Japan

    Science.gov (United States)

    Tanaka, A.; Abe, G.; Yamaguchi, K. E.

    2014-12-01

    Recent studies have shown that submarine hydrothermal system supports diverse microbial life. Bio-essential metals supporting such microbial communities were released from basalts by high-temperature water-rock interaction in deeper part of the oceanic crust and carried by submarine fluid flow. Its total quantity in global hydrothermal settings has been estimated to be on the order of ~1019 g/yr, which is surprisingly on the same order of the total river flows (Urabe et al., 2011). Therefore, it is important to explore how submarine river system works, i.e., to understand mechanism and extent of elemental transport, which should lead to understanding of the roles of hydrothermal circulation in oceanic crust in controlling elemental budget in the global ocean and geochemical conditions to support deep hot biosphere.  We performed REE analysis of marine sediments influenced by submarine hydrothermal activity in Mid-Okinawa Trough. The sediment samples used in this study are from IODP site at Iheya North region and JADE site at Izena region. The samples show alternation between volcanic and clastic sediments. Hydrothermal fluids of this area contain elevated concentrations of volatile components such as H2, CO2, CH4, NH4+, and H2S, supporting diverse chemoautotrophic microbial community (Nakagawa et al., 2005). The purpose of this study is to examine the effect of hydrothermal activity on the REE signature of the sediments. Chondrite-normalized REE patterns of the samples show relative enrichment of light over heavy REEs, weak positive Ce anomalies, and variable degrees of negative Eu anomalies. The REE patterns suggest the sediments source was mainly basalt, suggesting insignificant input of continental materials. Negative Eu anomalies found in the IODP site become more pronounced with increasing depth, suggesting progressive increase of hydrothermal alteration where Eu was reductively dissolved into fluids by decomposition of feldspars. Contrary, at the JADE site

  13. Physical, chemical and mineralogical evolution of the Tolhuaca geothermal system, southern Andes, Chile: Insights into the interplay between hydrothermal alteration and brittle deformation

    Science.gov (United States)

    Sanchez-Alfaro, Pablo; Reich, Martin; Arancibia, Gloria; Pérez-Flores, Pamela; Cembrano, José; Driesner, Thomas; Lizama, Martin; Rowland, Julie; Morata, Diego; Heinrich, Christoph A.; Tardani, Daniele; Campos, Eduardo

    2016-09-01

    In this study, we unravel the physical, chemical and mineralogical evolution of the active Tolhuaca geothermal system in the Andes of southern Chile. We used temperature measurements in the deep wells and geochemical analyses of borehole fluid samples to constrain present-day fluid conditions. In addition, we reconstructed the paleo-fluid temperatures and chemistry from microthermometry and LA-ICP-MS analysis of fluid inclusions taken from well-constrained parageneses in vein samples retrieved from a ~ 1000 m borehole core. Based on core logging, mineralogical observations and fluid inclusions data we identify four stages (S1-S4) of progressive hydrothermal alteration. An early heating event (S1) was followed by the formation of a clay-rich cap in the upper zone (chemical analyses of fluid inclusions and borehole fluids reveal a significant change in chemical conditions during the evolution of Tolhuaca. Whereas borehole (present-day) fluids are rich in Au, B and As, but Cu-poor (B/Na ~ 100.5, As/Na ~ 10- 1.1, Cu/Na ~ 10- 4.2), the paleofluids trapped in fluid inclusions are Cu-rich but poor in B and As (B/Na ~ 10- 1, As/Na ~ 10- 2.5, Cu/Na ~ 10- 2.5 in average). We interpret the fluctuations in fluid chemistry at Tolhuaca as the result of transient supply of metal-rich, magmatically derived fluids where As, Au and Cu are geochemically decoupled. Since these fluctuating physical and chemical conditions at the reservoir produced a mineralogical vertical segmentation of the system that affects the mechanical and hydrological properties of host rock, we explored the effect of the development of a low-cohesion low-permeability clay cap on the conditions of fault rupture and on the long-term thermal structure of the system. These analyses were performed by using rock failure condition calculations and numerical simulations of heat and fluid flows. Calculations of the critical fluid pressures required to produce brittle rupture indicate that within the clay-rich cap, the

  14. Similarities in the chemistry of shallow submarine hydrothermal vents

    Energy Technology Data Exchange (ETDEWEB)

    Prol-Ledesma, R.M. [UNAM, Mexico City (Mexico). Instituto de Geofisica

    2003-12-01

    Shallow submarine hydrothermal activity has been observed in Western Mexico related to extensional tectonic faults. Hydrothermal vents occur at Punta Banda on the Pacific coast of Baja California, at Bahia Concepcion on the eastern coast of Baja California, and in Punta Mita on the Pacific coast of central Mexico. Submarine discharge of geothermal fluids is located at depths varying between 5 and 30 m. Water and gas discharge at temperatures between 40 and more than 100{sup o}C. The composition of the thermal end-member can be calculated for Mg=0 using the chemistry data of the water samples. A linear regression of the concentration values vs magnesium content is used to determine the concentration of the end-member thermal water. The chemical composition of the thermal end-member indicates that the water is more dilute than seawater and enriched in Ca, Mn, Ba, I, Cs, B, Li, Rb, Sr and Si. The results show that the water chemistry is similar in these coastal hydrothermal systems. The thermal water is probably of meteoric origin, penetrating through the extensional faults, and heated by the high geothermal gradient. The components in the thermal water are contributed by the deep strata. (author)

  15. Imaging hydrothermal systems associated with oceanic ridge: ambient noise and travel-time tomographies in the Reykjanes high-temperature area, SW-Iceland.

    Science.gov (United States)

    Jousset, Philippe; Ágústsson, Kristjan; Verdel, Arie; Blanck, Hanna; Franke, Steven; Specht, Sebastian; Stefánsson, Stefán; Tryggvason, Hörður; Erbas, Kemal; Deon, Fiorenza; Erlendsson, Ögmundur; Guðnason, Egill; Hersir, Gylfi; Ryberg, Trond; Halldórsdóttir, Sæunn; Weemstra, Cornelius; Bruhn, David; Flovenz, Ólafur; Friðleifsson, Ómar

    2015-04-01

    Analogue outcrops of hydrothermal fossil systems and simulating pressure/temperature conditions in the laboratory are classical methods for assessing supercritical conditions in magmatic environments. Scientific drilling is used when Earth surface sampled rocks cannot sufficiently explain past geological processes and when geophysical imaging does not sufficiently explain observed phenomena. However, our understanding of structural and dynamic characteristics of geothermal systems can be improved through application of advanced and/or innovative exploration technologies. Unlike resistivity imaging, active and passive seismic techniques have rarely been used in volcanic geothermal areas, because processing techniques were not adapted to geothermal conditions. Recent advances in volcano-seismology have introduced new processing techniques for assessing subsurface structures and controls on fluid flow in geothermal systems. We present here preliminary analyses of seismic records around a geothermal reservoir located both on-land and offshore along the Reykjanes Ridge, SW-Iceland. We deployed 214 on-land stations and 24 Ocean Bottom Seismometers since April 2014. We analyse more than 6 months of part of those records. We present first results of both travel-time tomography and ambient noise tomography and we discuss briefly implications for geothermal exploration in volcanic contexts.

  16. Evolutionary strategies of viruses, bacteria and archaea in hydrothermal vent ecosystems revealed through metagenomics.

    Science.gov (United States)

    Anderson, Rika E; Sogin, Mitchell L; Baross, John A

    2014-01-01

    The deep-sea hydrothermal vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these systems, a high proportion of which are lysogenic, must also withstand these environmental extremes. Here, we explore the evolutionary strategies of both microorganisms and viruses in hydrothermal systems through comparative analysis of a cellular and viral metagenome, collected by size fractionation of high temperature fluids from a diffuse flow hydrothermal vent. We detected a high enrichment of mobile elements and proviruses in the cellular fraction relative to microorganisms in other environments. We observed a relatively high abundance of genes related to energy metabolism as well as cofactors and vitamins in the viral fraction compared to the cellular fraction, which suggest encoding of auxiliary metabolic genes on viral genomes. Moreover, the observation of stronger purifying selection in the viral versus cellular gene pool suggests viral strategies that promote prolonged host integration. Our results demonstrate that there is great potential for hydrothermal vent viruses to integrate into hosts, facilitate horizontal gene transfer, and express or transfer genes that manipulate the hosts' functional capabilities.

  17. Evolutionary strategies of viruses, bacteria and archaea in hydrothermal vent ecosystems revealed through metagenomics.

    Directory of Open Access Journals (Sweden)

    Rika E Anderson

    Full Text Available The deep-sea hydrothermal vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these systems, a high proportion of which are lysogenic, must also withstand these environmental extremes. Here, we explore the evolutionary strategies of both microorganisms and viruses in hydrothermal systems through comparative analysis of a cellular and viral metagenome, collected by size fractionation of high temperature fluids from a diffuse flow hydrothermal vent. We detected a high enrichment of mobile elements and proviruses in the cellular fraction relative to microorganisms in other environments. We observed a relatively high abundance of genes related to energy metabolism as well as cofactors and vitamins in the viral fraction compared to the cellular fraction, which suggest encoding of auxiliary metabolic genes on viral genomes. Moreover, the observation of stronger purifying selection in the viral versus cellular gene pool suggests viral strategies that promote prolonged host integration. Our results demonstrate that there is great potential for hydrothermal vent viruses to integrate into hosts, facilitate horizontal gene transfer, and express or transfer genes that manipulate the hosts' functional capabilities.

  18. Operation of the ELETRONORTE hydrothermal systems: Amazonas, Rondonia and Amapa States and Tucurui Hydroelectric Power Plant, focusing the El Nino phenomenon; Operacao dos sistemas hidrotermicos da ELETRONORTE: Amazonas, Rondonia, Amapa e Usina Hidroeletrica de Tucurui, enfocando o fenomeno El Nino

    Energy Technology Data Exchange (ETDEWEB)

    Costalonga, Isabela dos Reis; Ferreira, Vania Maria [Centrais Eletricas do Norte do Brasil S.A. (ELETRONORTE), Brasilia, DF (Brazil)]. E-mail: ceon@eln.gov.br

    1998-07-01

    This work presents an analysis of the ELETRONORTE hydrothermal systems in the States of Amazonas, Rondonia and Amapa and the Tucurui HPP Interconnected System. The analysis ranges from the whole year of 1997 to September 1998, considering the strong influence of the El Nino phenomenon, initiated on April 1997, on the flows affluent to the reservoirs of Balbina, Samuel, Coaracy Nunes and Tucurui Hydroelectric Power Plants.

  19. Seismo-acoustic evidence for an avalanche driven phreatic eruption through a beheaded hydrothermal system: An example from the 2012 Tongariro eruption

    Science.gov (United States)

    Jolly, A.D.; Jousset, P.; Lyons, J.J.; Carniel, R.; Fournier, R.; Fry, B.; Miller, C.

    2016-01-01

    The 6 August 2012 Te Maari eruption comprises a complex eruption sequence including multiple eruption pulses, a debris avalanche that propagated ~ 2 km from the vent, and the formation of a 500 m long, arcuate chasm, located ~ 300 m from the main eruption vent. The eruption included 6 distinct impulses that were coherent across a local infrasound network marking the eruption onset at 11:52:18 (all times UTC). An eruption energy release of ~ 3 × 1012 J was calculated using a body wave equation for radiated seismic energy. A similar calculation based on the infrasound record, shows that ~ 90% of the acoustic energy was released from three impulses at onset times 11:52:20 (~ 20% of total eruption energy), 11:52:27 (~ 50%), and 11:52:31 (~ 20%). These energy impulses may coincide with eyewitness accounts describing an initial eastward directed blast, followed by a westward directed blast, and a final vertical blast. Pre-eruption seismic activity includes numerous small unlocatable micro-earthquakes that began at 11:46:50. Two larger high frequency earthquakes were recorded at 11:49:06 and 11:49:21 followed directly by a third earthquake at 11:50:17. The first event was located within the scarp based on an arrival time location from good first P arrival times and probably represents the onset of the debris avalanche. The third event was a tornillo, characterised by a 0.8 Hz single frequency resonance, and has a resonator attenuation factor of Q ~ 40, consistent with a bubbly fluid filled resonator. This contrasts with a similar tornillo event occurring 2.5 weeks earlier having Q ~ 250–1000, consistent with a dusty gas charged resonator. We surmise from pre-eruption seismicity, and the observed attenuation change, that the debris avalanche resulted from the influx of fluids into the hydrothermal system, causing destabilisation and failure. The beheaded hydrothermal system may have then caused depressurisation frothing of the remaining gas charged system leading to the

  20. Hydrothermal conversion of biomass

    NARCIS (Netherlands)

    Knezevic, Dragan

    2009-01-01

    This thesis presents research of hydrothermal conversion of biomass (HTC). In this process, hot compressed water (subcritical water) is used as the reaction medium. Therefore this technique is suitable for conversion of wet biomass/ waste streams. By working at high pressures, the evaporation of wat

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

    Science.gov (United States)

    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

  2. Comparison of object and relational database systems

    OpenAIRE

    GEYER, Jakub

    2012-01-01

    This thesis focuses on the issue of a convenient choice of database platforms. The key features of the object database systems and the relational database systems are mutually compared and tested on concrete representative samples of each individual platform.

  3. Crustal controls on magmatic-hydrothermal systems: A geophysical comparison of White River, Washington, with Goldfield, Nevada

    Science.gov (United States)

    Blakely, R.J.; John, D.A.; Box, S.E.; Berger, B.R.; Fleck, R.J.; Ashley, R.P.; Newport, G.R.; Heinemeyer, G.R.

    2007-01-01

    for geologic mapping in identifying faults, fractures, and intrusions relevant to hydrothermal alteration and ore formation in areas of poor exposure. ?? 2006 Geological Society of America.

  4. Hydrothermal processing of radioactive combustible waste

    Energy Technology Data Exchange (ETDEWEB)

    Worl, L.A.; Buelow, S.J.; Harradine, D.; Le, L.; Padilla, D.D.; Roberts, J.H.

    1998-09-01

    Hydrothermal processing has been demonstrated for the treatment of radioactive combustible materials for the US Department of Energy. A hydrothermal processing system was designed, built and tested for operation in a plutonium glovebox. Presented here are results from the study of the hydrothermal oxidation of plutonium and americium contaminated organic wastes. Experiments show the destruction of the organic component to CO{sub 2} and H{sub 2}O, with 30 wt.% H{sub 2}O{sub 2} as an oxidant, at 540 C and 46.2 MPa. The majority of the actinide component forms insoluble products that are easily separated by filtration. A titanium liner in the reactor and heat exchanger provide corrosion resistance for the oxidation of chlorinated organics. The treatment of solid material is accomplished by particle size reduction and the addition of a viscosity enhancing agent to generate a homogeneous pumpable mixture.

  5. The BGU/CERN solar hydrothermal reactor

    CERN Document Server

    Bertolucci, Sergio; Caspers, Fritz; Garb, Yaakov; Gross, Amit; Pauletta, Stefano

    2014-01-01

    We describe a novel solar hydrothermal reactor (SHR) under development by Ben Gurion University (BGU) and the European Organization for Nuclear Research CERN. We describe in broad terms the several novel aspects of the device and, by extension, of the niche it occupies: in particular, enabling direct off-grid conversion of a range of organic feedstocks to sterile useable (solid, liquid) fuels, nutrients, products using only solar energy and water. We then provide a brief description of the high temperature high efficiency panels that provide process heat to the hydrothermal reactor, and review the basics of hydrothermal processes and conversion taking place in this. We conclude with a description of a simulation of the pilot system that will begin operation later this year.

  6. Effect of condensation agents and minerals for oligopeptide formation under mild and hydrothermal conditions in related to chemical evolution of proteins

    Science.gov (United States)

    Kawamura, Kunio; Takeya, Hitoshi; Kushibe, Takao

    2009-07-01

    The role of condensation agents and minerals for oligopeptide formation was inspected to see whether minerals possess catalytic activity under mild and hydrothermal conditions. Under mild conditions, oligopeptide formation from negatively charged amino acids (Asp and Glu) using different minerals and the elongation of alanine oligopeptides ((Ala) 2-(Ala) 5) were attempted using apatite minerals. Oligo(Asp) up to 10 amino acid units from Asp were observed in the presence of 1-ethyl-3-(3-dimethylaminopropyl carbodiimide (EDC). Notable influence of minerals was not detected for the oligo(Asp) formation. Oligo(Asp) was gradually degraded by the further incubation in the presence of EDC in both the absence and presence of minerals. The formation of oligo(Glu) was less efficient in the presence of carbonyldiimidazole. The elongation from (Ala) 3, (Ala) 4, and (Ala) 5 and the formation of diketopiperazine from (Ala) 2 proceeded immediately in the presence of EDC in the meantime of the sample preparations. In addition, it was unexpected that the disappearance of the products and the reformation of the reactants occurred by the further incubation for 24 h; for instance, (Ala) 5 decreased but (Ala) 4 increased with increasing the reaction time in the reaction of (Ala) 4 with EDC. These facts suggest that the activation of the reactant amino acids or peptides immediately occurs. Under the simulated hydrothermal conditions, EDC did not enhance the formation of oligopeptides from Asp, Glu or Ala nor the spontaneous formation of (Ala) 5 from (Ala) 4.

  7. Multiple episodes of hydrothermal activity and epithermal mineralization in the southwestern Nevada volcanic field and their relations to magmatic activity, volcanism and regional extension

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, S.I.; Noble, D.C.; Jackson, M.C. [Univ. of Nevada, Reno, NV (United States)] [and others

    1994-12-31

    Volcanic rocks of middle Miocene age and underlying pre-Mesozoic sedimentary rocks host widely distributed zones of hydrothermal alteration and epithermal precious metal, fluorite and mercury deposits within and peripheral to major volcanic and intrusive centers of the southwestern Nevada volcanic field (SWNVF) in southern Nevada, near the southwestern margin of the Great Basin of the western United States. Radiometric ages indicate that episodes of hydrothermal activity mainly coincided with and closely followed major magmatic pulses during the development of the field and together spanned more than 4.5 m.y. Rocks of the SWNVF consist largely of rhyolitic ash-flow sheets and intercalated silicic lava domes, flows and near-vent pyroclastic deposits erupted between 15.2 and 10 Ma from vent areas in the vicinity of the Timber Mountain calderas, and between about 9.5 and 7 Ma from the outlying Black Mountain and Stonewall Mountain centers. Three magmatic stages can be recognized: the main magmatic stage, Mountain magmatic stage (11.7 to 10.0 Ma), and the late magmatic stage (9.4 to 7.5 Ma).

  8. Reactivity of organic-rich sediment in seawater at 350°c, 500 bars: experimental and theoretical constraints and implications for the guaymas basin hydrothermal system

    Science.gov (United States)

    Thornton, Edward C.; Seyfried, W. E., Jr.

    1987-07-01

    Hydrothermal alteration of organic-rich diatomaceous sediment by seawater was modelled experimentally at 350°C, 500 bars and seawater/sediment mass ratio of 3. The experiment was performed to assess the effect of organic matter reactivity on solution speciation and sediment alteration processes at an elevated temperature and pressure and provide requisite data to better understand the chemistry of hydrothermal fluids issuing from vents in the Guaymas Basin, Gulf of California. Seawater chemistry changed greatly during the experiment. In particular, Na, Mg and SO 4 decreased, while ∑ CO 2, ∑ NH 3, ∑ H 2S, SiO 2, Ca, K, H 2, CH 4 and heavy and base metals increased. Moreover, owing to the thermal alteration of sediment organic matter, organic acids, phenolic derivatives and phthlate were released to solution. Examination of solid alteration products revealed the effects of extensive dissolution and precipitation processes characterized by total elimination of diatoms and formation of cristobalite, quartz (?), pyrite, pyrrhotite, mixed layer chlorite/smectite and calcite. Plagioclase feldspar (An 40) recrystallized to a more albitic form owing to Na fixation and Ca cycling to calcite. A graphitic residue was also present in the products of the experiment. Mg and Na fixation reactions during the experiment generated significant H +, although the pH measured at 25°C was approximately 6.2. SO 4 reduction and thermal alteration and dissolution of organics, however, consume H + and are chiefly responsible for the near neutral pH for the overall reaction. Speciation calculations including ammine and acetate protonation reactions give a pH at experimental conditions of approximately 5.1, while mineral solubility relations involving virtually all alteration phases require a pH of 5.57 to 5.94. A near neutral pH at experimental conditions constrains the mobility of Fe, Mn, Zn, Cu and Ni, which existed in solution as chloro-complexes. Dissolved concentrations of Pb and

  9. Anhydrite Solubility and Ca Isotope Fractionation in the Vapor-Liquid Field of the NaCl-H2O System: Implications for Hydrothermal Vent Fluids at Mid-ocean Ridges

    Science.gov (United States)

    Scheuermann, P.; Syverson, D. D.; Higgins, J. A.; Seyfried, W. E., Jr.

    2015-12-01

    Hydrothermal experiments were performed at 410, 420 and 450°C between 180-450 bar to investigate anhydrite (CaSO4) solubility and Ca isotope fractionation in the liquid-vapor stability field of the NaCl-H2O system. Experiments were conducted in flexible gold reaction cells and a fixed volume Ti reactor to reach all pressures between the critical curve and three-phase boundary. During isothermal decompression at 410°C, anhydrite solubility in the liquid phase increases (1 to 9 mmol/kg Ca), whereas the solubility decreases in the vapor phase (130 to systems with implications for mass transfer reactions at/near the magma-hydrothermal boundary at mid-ocean ridges.

  10. Peptide synthesis under Enceladus hydrothermal condition

    Science.gov (United States)

    Fujishima, Kosuke; Takano, Yoshinori; Takai, Ken; Takahagi, Wataru; Adachi, Keito; Shibuya, Takazo; Tomita, Masaru

    2016-07-01

    Enceladus is one of the moons of Saturn, and it has been known to harbor interior ocean beneath the icy crust. The mass spectrometry data obtained by Cassini spacecraft indicates the presence of salty, and most likely alkaline ocean containing various organic compounds. While geochemical and other radiation related processes for in situ production of organics remain elusive, thermally unaltered carbonaceous chondrites, consisting the main body of Enceladus are known to be enriched with organic matters potentially including the building blocks of life (e.g., amino acids and amino acid precursors). Assuming that abiotic amino acids exist in the Enceladus alkaline seawater, we hypothesized that water-rock interaction may contribute to condensation of localized amino acids leading to peptide formation. In order to test this hypothesis, we have developed the Enceladus hydrothermal reactor based on the chemical constraints obtained through previous experimental and theoretical studies. We have added six different amino acids and introduced a thermal fluctuation system simulating the periodic tidal heating of the interior chondritic core. Total, eight sea water samples were obtained over the course of 147 days of experiment. While detection of peptide using Capillary Electrophoresis Time-of-Flight Mass Spectrometry (CE-TOF/MS) is still at the preliminary stage, so far pH monitoring and H2 and CO2 Gas Chromatography Mass Spectrometry (GC-MS) data clearly indicated the occurrence of serpentinization/carbonation reaction. Here, we discuss the interaction between aqueous alteration reactions and thermal cycling processes for the role of abiotic peptide formation under the Enceladus hydrothermal condition.

  11. Oxygen and hydrogen isotope study of the Skaergaard intrusion and its country rocks: a description of a 55-M. Y. old fossil hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, H.P. Jr. (California Inst. of Tech., Pasadena); Forester, R.W.

    1979-08-01

    Oxygen isotope analyses have been obtained on rocks and coexisting minerals, principally plagioclase and clinopyroxene, from about 400 samples of the Skaergaard layered gabbro intrusion and its country rocks. The delta/sup 18/O values of plagioclase decrease upward in the intrusion, from normal values of about +6.0 to +6.4 in the Lower Zone and parts of the Middle Zone, to values as low as -2.4 in the Upper Border Group. The /sup 18/O depletions of the plagioclase all took place under subsolidus conditions, and were produced by the Eocene meteoric-hydrothermal system established by this pluton. Clinopyroxene, which is more resistant to /sup 18/O exchange than is plagioclase, also underwent depletion in /sup 18/O, but to a lesser degree. The /sup 18/O-depleted rocks typically show reversed ..delta../sup 18/O/sub plag-px/ fractionations, except at the top of the Upper Zone, where the pyroxenes are very fine-grained aggregates pseudomorphous after ferrowollastonite; these inverted pyroxenes were much more susceptible to subsolidus /sup 18/O exchange. D/H analyses of the chloritized basalt country rocks and of the minor quantities of alteration minerals in the pluton (delta D = -116 to -149) confirm these interpretations, indicating that the rocks interacted with meteoric groundwaters.

  12. Mathematical modeling of diffuse flow in seafloor hydrothermal systems: The potential extent of the subsurface biosphere at mid-ocean ridges

    Science.gov (United States)

    Lowell, R. P.; Houghton, J. L.; Farough, A.; Craft, K. L.; Larson, B. I.; Meile, C. D.

    2015-09-01

    We describe a variety of one- and two-dimensional mathematical modeling approaches to characterizing diffuse flow circulation at mid-ocean ridge hydrothermal systems. The goal is to estimate the potential extent of the sub-seafloor microbial biosphere based on subsurface contours of the 120 °C isotherm as determined from the various models. The models suggest that the sub-seafloor depth for microbial life may range from less than 1 m in some places to the thickness of crustal layer 2A of ∼ 500 m in others. This depth depends primarily on how diffuse flow is driven. The 120 °C isotherm tends to be much deeper if diffuse flow is induced as boundary layer flow near high-temperature plumes, than if it results from conductive cooling or mixing near the seafloor. Because the heat flow alone may not allow identification of the flow regime in the subsurface, we highlight the use of chemical tracers as an additional constraint that sheds light into the flow and reaction patterns associated with vents. We use thermodynamic modeling, which connects the temperature of the diffuse fluid to its chemical composition. As the temperature-composition relationships differ for mixing versus conductive heating and cooling, the fluid geochemistry can shed light on subsurface transport. Using methane as an example, the geochemical models indicate subsurface microbial methane production and consumption in different regions of the vent field near EPR 9 °50‧ N.

  13. Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough.

    Science.gov (United States)

    Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

    2015-01-01

    There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has

  14. Mobility of Au and related elements during the hydrothermal alteration of the oceanic crust: implications for the sources of metals in VMS deposits

    Science.gov (United States)

    Patten, Clifford G. C.; Pitcairn, Iain K.; Teagle, Damon A. H.; Harris, Michelle

    2016-02-01

    Volcanogenic massive sulphide (VMS) deposits are commonly enriched in Cu, Zn and Pb and can also be variably enriched in Au, As, Sb, Se and Te. The behaviour of these elements during hydrothermal alteration of the oceanic crust is not well known. Ocean Drilling Program (ODP) Hole 1256D penetrates a complete in situ section of the upper oceanic crust, providing a unique sample suite to investigate the behaviour of metals during hydrothermal alteration. A representative suite of samples was analysed for Au, As, Sb, Se and Te using low detection limit methods, and a mass balance of metal mobility has been carried out through comparison with a fresh Mid-Oceanic Ridge Basalt (MORB) glass database. The mass balance shows that Au, As, Se, Sb, S, Cu, Zn and Pb are depleted in the sheeted dyke and plutonic complexes by -46 ± 12, -27 ± 5, -2.5 ± 0.5, -27 ± 6, -8.4 ± 0.7, -9.6 ± 1.6, -7.9 ± 0.5 and -44 ± 6 %, respectively. Arsenic and Sb are enriched in the volcanic section due to seawater-derived fluid circulation. Calculations suggest that large quantities of metal are mobilised from the oceanic crust but only a small proportion is eventually trapped as VMS mineralisation. The quantity of Au mobilised and the ratio of Au to base metals are similar to those of mafic VMS, and ten times enrichment of Au would be needed to form a Au-rich VMS. The Cu-rich affinity of mafic VMS deposits could be explained by base metal fractionation both in the upper sheeted dykes and during VMS deposit formation.

  15. Hydrothermal synthesis of hydroxyapatite

    Science.gov (United States)

    Earl, J. S.; Wood, D. J.; Milne, S. J.

    2006-02-01

    A hydrothermal method of synthesizing hydroxyapatite by heating a precipitate, formed by mixing Ca(NO3)2bold dot4H2O and (NH4)2HPO4 with distilled water, in a hydrothermal reactor at 200 °C for 24-72 hrs is described. A treatment time of 24 hrs produced single phase (as shown by XRD) hydroxyapatite powder, however for longer treatment times XRD patterns were indicative of the presence of a secondary phase, monetite (CaHPO4). SEM examination of the treated powders displayed particles of rod-like morphology with dimensions 100-500 nm in length and 10-60 nm in diameter. Preliminary results on the use of the particles for the infiltration of dentine tubules are presented.

  16. Hydrothermal synthesis of hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Earl, J S; Wood, D J; Milne, S J [Institute for Materials Research, University of Leeds, Leeds, LS2 9JT (United Kingdom)

    2006-02-22

    A hydrothermal method of synthesizing hydroxyapatite by heating a precipitate, formed by mixing Ca(NO{sub 3}){sub 2}{center_dot}4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4} with distilled water, in a hydrothermal reactor at 200 deg. C for 24-72 hrs is described. A treatment time of 24 hrs produced single phase (as shown by XRD) hydroxyapatite powder, however for longer treatment times XRD patterns were indicative of the presence of a secondary phase, monetite (CaHPO{sub 4}). SEM examination of the treated powders displayed particles of rod-like morphology with dimensions 100-500 nm in length and 10-60 nm in diameter. Preliminary results on the use of the particles for the infiltration of dentine tubules are presented.

  17. Laboratory simulated hydrothermal alteration of sedimentary organic matter from Guaymas Basin, Gulf of California. Ph.D. Thesis

    Science.gov (United States)

    Leif, Roald N.

    1993-01-01

    High temperature alteration of sedimentary organic matter associated with marine hydrothermal systems involves complex physical and chemical processes that are not easily measured in most natural systems. Many of these processes can be evaluated indirectly by examining the geochemistry of the hydrothermal system in the laboratory. In this investigation, an experimental organic geochemical approach to studying pyrolysis of sedimentary organic matter is applied to the hydrothermal system in the Guaymas Basin, Gulf of California. A general survey of hydrothermal oils and extractable organic matter (bitumen) in hydrothermally altered sediments identified several homologous series of alkanones associated with a high temperature hydrothermal origin. The alkanones range in carbon number from C11 to C30 with no carbon number preference. Alkan-2-ones are in highest concentrations, with lower amounts of 3-, 4-, 5- (and higher) homologs. The alkanones appear to be pyrolysis products synthesized under extreme hydrothermal conditions. Hydrous pyrolysis and confinement pyrolysis experiments were performed to simulate thermally enhanced diagenetic and catagenetic changes in the immature sedimentary organic matter. The extent of alteration was measured by monitoring the n-alkanes, acyclic isoprenoids, steroid and triterpenoid biomarkers, polycyclic aromatic hydrocarbons and alkanones. The results were compared to bitumen extracts from sediments which have been naturally altered by a sill intrusion and accompanied hydrothermal fluid flow. These pyrolysis experiments duplicated many of the organic matter transformations observed in the natural system. Full hopane and sterane maturation occurred after 48 hr in experiments at 330 deg C with low water/rock mass ratios (0.29). A variety of radical and ionic reactions are responsible for the organic compound conversions which occur under extreme hydrothermal conditions. Short duration pyrolysis experiments revealed that a portion of the

  18. Centrifugal separator devices, systems and related methods

    Science.gov (United States)

    Meikrantz, David H.; Law, Jack D.; Garn, Troy G.; Todd, Terry A.; Macaluso, Lawrence L.

    2012-03-20

    Centrifugal separator devices, systems and related methods are described. More particularly, fluid transfer connections for a centrifugal separator system having support assemblies with a movable member coupled to a connection tube and coupled to a fixed member, such that the movable member is constrained to movement along a fixed path relative to the fixed member are described. Also, centrifugal separator systems including such fluid transfer connections are described. Additionally, methods of installing, removing and/or replacing centrifugal separators from centrifugal separator systems are described.

  19. Effects of hydrothermal unrest on stress and deformation: insights from numerical modeling and application to Vulcano Island (Italy)

    Science.gov (United States)

    Currenti, Gilda; Napoli, Rosalba; Coco, Armando; Privitera, Emanuela

    2017-04-01

    A numerical approach is proposed to evaluate stress and deformation fields induced by hydrothermal fluid circulation and its influence on volcano-flank stability. The numerical computations have been focused on a conceptual model of Vulcano Island, where geophysical, geochemical, and seismic signals have experienced several episodes of remarkable changes likely linked to the hydrothermal activity. We design a range of numerical models of hydrothermal unrest and computed the associated deformation and stress field arising from rock-fluid interaction processes related to the thermo-poroelastic response of the medium. The effects of model parameters on deformation and flank stability are explored considering different multilayered crustal structures constrained by seismic tomography and stratigraphy investigations. Our findings highlight the significant role of model parameters on the response of the hydrothermal system and, consequently, on the amplitudes and the timescale of stress and strain fields. Even if no claim is made that the model strictly applies to the crisis episodes at Vulcano, the numerical results are in general agreement with the pattern of monitoring observations, characterized by an enhancing of gas emission and seismic activity without significant ground deformation. The conceptual model points to a pressurization and heating of the shallow hydrothermal system (1-0.25 km bsl) fed by fluid of magmatic origin. However, for the assumed values of model material and source parameters (rate of injection, fluid composition, and temperature), the pressure and temperature changes do not affect significantly the flank stability, which is mainly controlled by the gravitational force.

  20. The chemistry of hydrothermal magnetite: a review

    Science.gov (United States)

    Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John

    2014-01-01

    Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of hydrothermal magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, hydrothermal magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in hydrothermal magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of hydrothermal and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United

  1. Characteristics of Hydrothermal Mineralization in Ultraslow Spreading Ridges

    Science.gov (United States)

    Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.

    2014-12-01

    Hydrothermal activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in hydrothermal fields. Structures formed by lower temperature activities in active and dead hydrothermal fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in hydrothermal chimneys. Distribution of diverse low temperature hydrothermal activities is consistence with the deep heating mechanisms and hydrothermal circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the

  2. Super eruption environments make for "super" hydrothermal explosions: Extreme hydrothermal explosions in Yellowstone National Park

    Science.gov (United States)

    Morgan, L. A.; Shanks, W. P.; Pierce, K. L.

    2006-12-01

    Hydrothermal explosions are violent events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments over areas that range from a few meters in diameter up to several kilometers in diameter. Hydrothermal explosions occur where shallow interconnected reservoirs of steam-saturated fluids underlie thermal fields. Sudden reduction in pressure causes the fluids to flash to steam resulting in significant expansion, rock fragmentation, and debris ejection. In Yellowstone, at least 20 large (>100 meters in diameter) hydrothermal explosions have been identified, and the scale of the individual events dwarfs similar features in other hydrothermal and geothermal areas of the world. Large explosions in Yellowstone have occurred over the past 16 ka at an interval of ~1 per every 700 yrs and similar events are likely to occur in the future. Our studies of hydrothermal explosive events indicate: 1) none are associated with magmatic or volcanic events; 2) several have been triggered by seismic events coupled with other processes; 3) lithic clasts and matrix from explosion deposits are extensively altered, indicating long-term, extensive hydrothermal mineralization in areas that were incorporated into the explosion deposit; 4) many lithic clasts in explosion breccia deposits contain evidence of repeated fracturing and cementation; and 4) dimensions of many documented large hydrothermal explosion craters in Yellowstone are similar to the dimensions of currently active geyser basins or thermal areas in Yellowstone. The vast majority of active thermal areas in Yellowstone are characterized by 1) high-temperature hot-water systems in areas of high heat-flow, 2) extensive systems of hot springs, fumaroles, geysers, sinter terraces, mud pots, and, in places, small hydrothermal explosion craters, 3) widespread alteration of host rocks, 4) large areal dimensions (>several 100 m) and 5) intermittent but long-lived activity (40,000 to 300,000 years). Critical

  3. 3-D seismic imaging of lithospheric fault-block structures, core complexes, alteration fronts, and hydrothermal systems along the Mid-Atlantic Ridge, Rainbow area

    Science.gov (United States)

    Dunn, R. A.; Arai, R.; Eason, D. E.; Canales, J. P.; Sohn, R. A.

    2016-12-01

    Oceanic lithosphere formed along slow-spreading mid-ocean ridges is structurally and compositionally heterogeneous due to spatial and temporal variations in tectonic extension and magmatic accretion processes. Sorting out the different influences requires detailed imaging of the subsurface. The MARINER seismic and geophysical mapping experiment was designed to examine seafloor spreading across an area that includes a non-transform offset of the Mid-Atlantic Ridge, 36°14'N, the site of the Rainbow core complex and its associated hydrothermal vent field. Using seismic refraction data from this experiment, we constructed three-dimensional anisotropic tomographic images of the crust and upper mantle around the Rainbow area. Approaching Rainbow along the spreading ridges from either side, the seismic images reveal the onset of a clear ridge-parallel stripe-like structures, with alternating high- and low-velocities throughout the crust, correlated with changing lower crustal thickness and the locations of large normal faults. The pattern indicates that large normal faults rotate large blocks of the entire crust during tectonic stretching. Sitting within the ridge offset, the Rainbow core complex appears to be genetically related to neighboring fault blocks, and is largely an ultramafic exposure. Relatively low seismic velocities drape the core complex, having a sharp contact with higher-velocities below. The sharp contact may demarcate alteration (to serpentinite) and cracking fronts, since also draping the core complex are corresponding regions of high seismic anisotropy and high microseismicity, indicating pervasive cracking of its upper regions. The anisotropy and seismicity funnel upwards under the vent field, presumably marking the flow paths of vent fluids that cool melt lenses found to be intruded deep below the surface. The tomographic images reveal lithospheric structures in greater detail than previously possible, and when taken together with our other

  4. Stochastic relations foundations for Markov transition systems

    CERN Document Server

    Doberkat, Ernst-Erich

    2007-01-01

    Collecting information previously scattered throughout the vast literature, including the author's own research, Stochastic Relations: Foundations for Markov Transition Systems develops the theory of stochastic relations as a basis for Markov transition systems. After an introduction to the basic mathematical tools from topology, measure theory, and categories, the book examines the central topics of congruences and morphisms, applies these to the monoidal structure, and defines bisimilarity and behavioral equivalence within this framework. The author views developments from the general

  5. A Relational Database System for Student Use.

    Science.gov (United States)

    Fertuck, Len

    1982-01-01

    Describes an APL implementation of a relational database system suitable for use in a teaching environment in which database development and database administration are studied, and discusses the functions of the user and the database administrator. An appendix illustrating system operation and an eight-item reference list are attached. (Author/JL)

  6. Monitoring Distributed Systems: A Relational Approach.

    Science.gov (United States)

    1982-12-01

    Feldman&Rovner 69]. Recently, several graphics systems employing a relational data base have been implemented [ Becerril et al. 79, Williams 74, Herot 80...Intelligent Gateway: System Overview. IEEE Transactions on Software Engineering SE-2(4), December, 1976. [ Becerril et al. 79] J. Becerril , R

  7. 230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge

    Science.gov (United States)

    Yang, Weifang; Tao, Chunhui; Li, Huaiming; Liang, Jin; Liao, Shili; Long, Jiangping; Ma, Zhibang; Wang, Lisheng

    2016-11-01

    Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28'E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the 230Th/238U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5-2.9 million tons.

  8. Comment on 'Consequences of phase separation on the distribution of hydrothermal fluids at ASHES vent field, axial volcano, Juan de Fuca ridge' by Christopher G. Fox

    Science.gov (United States)

    Scholl, M. A.; Ingebritsen, S. E.; Essaid, H. I.

    1993-02-01

    Fox (1990), in order to explain observations during the Axial Seamount Hydrothermal Emissions Study (ASHES), proposed a conceptual model for a two-phase subsea hydrothermal system in which steam controlled flow patterns by blocking liquid flow. An attempt is made here to demonstrate with a very general model that relative permeability contrasts by themselves do not cause spatial isolation of phases in steam/liquid water systems and that density segregation, independent of relative permeability effects, should not be ruled out as an explanation for the observations at the ASHES site. Fox replies that density segregation is probably not the only mechanism at work.

  9. U and Th Concentration and Isotopic Composition of Hydrothermal Fluids at the Lost City Hydrothermal Field

    Science.gov (United States)

    Ludwig, K. A.; Shen, C.; Cheng, H.; Edwards, R.; Kelley, D. S.; Butterfield, D. A.

    2006-12-01

    Uranium and Th concentration and isotopic composition of hydrothermal fluids at the Lost City Hydrothermal Field (LCHF) were determined using multi-collector inductively coupled plasma mass spectrometry (MC-ICP- MS). The LCHF is an off-axis, serpentinite-hosted hydrothermal system located at 30°N near the Mid- Atlantic Ridge. Carbonate chimneys reaching 60 m in height vent alkaline (pH~10), calcium-rich fluids at 40- 91°C and the towers are home to dense microbial communities. Vent fluid and seawater U and Th concentration and isotopic composition data provide critical information for constraining U-Th chimney ages. The increased sensitivity (1-2%) of MC-ICP-MS combined with an Aridus nebulization system allows the precise measurement of small quantities of sample (~150 ml) with low concentrations (ICP-MS techniques to measure the U and Th concentration and isotopic composition (234U, 238U, 230Th, and 232Th) of eight hydrothermal fluid samples. Endmember fluids with ~1mmol/kg Mg have ~0.02 ng/g U, confirming that end-member fluids contain near-zero values of both Mg and U. Thorium concentrations of fluids are close to deep seawater values. U and Th isotopic compositions are reported at the permil level. These data may provide new insights into the role of serpentinite-hosted hydrothermal systems in the budgets of U and Th in the ocean. Techniques presented in this study may be applied to other hydrothermal and seep environments.

  10. Hydrothermal system of the Papandayan Volcano, West Java, Indonesia and its geochemistry evolution of thermal water after the November 2002 eruption

    Directory of Open Access Journals (Sweden)

    Agnes Mazot

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol2no1.20072Papandayan is a strato volcano situated in West Java, Indonesia. After the last magmatic eruptionin 1772, only few phreatic explosions have been occurring. At the present time, the activity is centeredin the northeast crater manifested by the presence of fumaroles and hot springs. In November 2002an explosive eruption occurred and ejected ash and altered rocks. Study of the altered rocks revealedthat an advanced argillic alteration took place in the hydrothermal system by an interaction betweenacid fl uids and rocks. Four zones of alteration have been formed as a limited extension along faults oracross permeable structures at different levels beneath the active crater of the volcano.Two types of acid fl uids are distinguished in the crater of the Papandayan Volcano: (1 acidsulphate-chloride water with pH values between 1.6 and 4.6, and (2 acid sulphate water with pHvalues between 1.2 and 2.5. The samples collected after the eruption revealed an increase in the SO4/Cl and Mg / Cl ratios. This evolution is likely explained by an increase in the neutralization of acidfl uids which tends to show that water-rock interactions were more signifi cant after the eruption. Thechanges in chemistry observed in 2003 were the consequence of the opening of new fractures whereunaltered or less altered volcanic rocks were in contact with the ascending acid water. The high δ34Svalues (9-17‰ observed in the acid sulphate-chloride water before the November 2002 eruptionsuggest that dissolved sulphates were mainly formed by the disproportionation of magmatic SO2. Onthe other hand, the low δ34S values (-0.3-7 ‰ observed in acid sulphate-chloride water sampled afterthe eruption suggest that the origin of dissolved sulphates for these waters is the surfi cial oxidation ofhydrogen sulphide.

  11. Hydrothermal system of the Papandayan Volcano, West Java, Indonesia and its geochemistry evolution of thermal water after the November 2002 eruption

    Directory of Open Access Journals (Sweden)

    Agnes Mazot

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol2no1.20072Papandayan is a strato volcano situated in West Java, Indonesia. After the last magmatic eruptionin 1772, only few phreatic explosions have been occurring. At the present time, the activity is centeredin the northeast crater manifested by the presence of fumaroles and hot springs. In November 2002an explosive eruption occurred and ejected ash and altered rocks. Study of the altered rocks revealedthat an advanced argillic alteration took place in the hydrothermal system by an interaction betweenacid fl uids and rocks. Four zones of alteration have been formed as a limited extension along faults oracross permeable structures at different levels beneath the active crater of the volcano.Two types of acid fl uids are distinguished in the crater of the Papandayan Volcano: (1 acidsulphate-chloride water with pH values between 1.6 and 4.6, and (2 acid sulphate water with pHvalues between 1.2 and 2.5. The samples collected after the eruption revealed an increase in the SO4/Cl and Mg / Cl ratios. This evolution is likely explained by an increase in the neutralization of acidfl uids which tends to show that water-rock interactions were more signifi cant after the eruption. Thechanges in chemistry observed in 2003 were the consequence of the opening of new fractures whereunaltered or less altered volcanic rocks were in contact with the ascending acid water. The high δ34Svalues (9-17‰ observed in the acid sulphate-chloride water before the November 2002 eruptionsuggest that dissolved sulphates were mainly formed by the disproportionation of magmatic SO2. Onthe other hand, the low δ34S values (-0.3-7 ‰ observed in acid sulphate-chloride water sampled afterthe eruption suggest that the origin of dissolved sulphates for these waters is the surfi cial oxidation ofhydrogen sulphide.

  12. A Method for Detection of Trace Concentrations of Underivatized Amino Acid in Hydrothermal Fluids by Ion-Pairing Reversed-Phase UPLC-ESI-QTOF-MS

    OpenAIRE

    Konn, Cecile; Magner, Jörgen; Charlou, Jean-luc; Holm, Nils G.; Alsberg, Tomas

    2015-01-01

    Investigation of amino acids in hydrothermal systems is of prime importance for the understanding of geochemistry and microbiology of hydrothermal vents and plumes, for carbon and metals global cycles, for metabolism of some hydrothermal microorganisms and for the origin of life issue. Extensive theoretical and experimental work on amino acids behaviour in hydrothermal fluids has been done, conversely only few dat