Fluid Phase Separation Processes in Submarine Hydrothermal Systems

Foustoukos, Dionysis I.; Seyfried, William E.

doi:10.2138/rmg.2007.65.7

Cited by 84 publications

(52 citation statements)

References 146 publications

(219 reference statements)

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“…Although phase separation is occurring at Pual Ridge (as discussed previously) and experimental studies have shown that both subcritical and supercritical phase separation processes occurring in seafloor hydrothermal systems can affect the hydrogen and oxygen isotopic composition of vent waters (Horita et al, 1995;Shmulovich et al, 1999;Foustoukos and Seyfried, 2007b) while the reverse is true for oxygen isotope partitioning Foustoukos and Seyfried, 2007b). Examination of the PACMANUS fluids reveals no systematic variations in δD H2O or δ 18 O H2O with endmember Cl (Table 5.2).…”

Section: Isotopic Evidence For Magmatic H 2 Omentioning

confidence: 74%

“…While propose that generation of a vapor phase with highly negative δD H2O and positive δ 18 O H2O values is conceivable under a scenario of combined water/rock reaction and open-system phase separation during isobaric heating (i.e. by subsurface dike emplacement), it requires segregation of a heavily distilled vapor (Foustoukos and Seyfried, 2007b). No such dilute vapors were observed at PACMANUS.…”

Section: Isotopic Evidence For Magmatic H 2 Omentioning

confidence: 97%

“…While we can demonstrate much of this variability is due to phase separation, prior magmatic-or rock-derived Cl inputs cannot be ruled out in the case of Pual Ridge fluids. Cl variations in MOR hydrothermal fluids beyond that permissible by rock hydration effects are typically attributed to phase separation (Von Damm, 1990;Von Damm, 1995;German and Von Damm, 2003;Foustoukos and Seyfried, 2007b) and rock-derived Cl is typically not considered a significant source to mid-ocean ridge vent fluids due to the low Cl content of MORB (Michael and Schilling, 1989;Michael and Cornell, 1998).…”

Section: Phase Separation and CL Variabilitymentioning

confidence: 99%

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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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This thesis presents the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting hydrothermal fluid compositions. Chapters 2 and 3 concern the abiotic (nonbiological) formation of organic compounds in high temperature vent fluids, a process which has direct implications for the emergence of life in early Earth settings and sustainment of present day microbial populations in hydrothermal environments. Chapter 2 represents an experimental investigation of methane (CH 4 ) formation under hydrothermal conditions. The overall reduction of carbon dioxide (CO 2 ) to CH 4 , previously assumed to be kinetically inhibited in the absence of mineral catalysts, is shown to proceed on timescales pertinent to crustal residence times of hydrothermal fluids. In Chapter 3, the abundance of methanethiol (CH 3 SH), considered to be a crucial precursor for the emergence of primitive chemoautotrophic life, is characterized in vent fluids from ultramafic-, basalt-and sediment-hosted hydrothermal systems. Previous assumptions that CH 3 SH forms by reduction of CO 2 are not supported by the observed distribution in natural systems. Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding alkenes, which are feasible in natural systems. In Chapter 5, the controls on vent fluid composition in a backarc hydrothermal system are investigated. A comprehensive survey of the inorganic geochemistry of fluids from sites of hydrothermal activity in the eastern Manus Basin indicates that fluids there are influenced by input of acidic magmatic solutions at depth, and subsequently modified by variable extents of seawater entrainment and mixing-related secondary acidity production. CHAPTER 1 IntroductionSeafloor hydrothermal systems associated with the generation of oceanic crust represent a dramatic expression of heat and mass transfer from the interior of the Earth. In addition to profound effects on ocean chemistry, convective circulation of seawater through volcanically active oceanic crust leads to the formation of metal sulfide deposits. In addition, seafloor hot springs are often invoked as ideal settings from which early microbial life could have emerged.Since the initial discovery of low temperature venting at the Galápagos Spreading Center in 1977 (CORLISS et al., 1979), our understanding of the composition and diversity of hydrothermal solutions has expanded greatly. During convection through oceanic crust of basaltic composition, O 2 -replete seawater reacts with crustal rock, typically producin...

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Section: Isotopic Evidence For Magmatic H 2 Omentioning

confidence: 74%

Section: Isotopic Evidence For Magmatic H 2 Omentioning

confidence: 97%

Section: Phase Separation and CL Variabilitymentioning

confidence: 99%

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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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“…dQ o is the observed temperature anomaly, NBL depth is the observed neutral buoyant layer depth, nominal source depth is the bottom depth under the observed plume signals, BF depth is the best fit source depth based on model results, nominal rise height is the rise height estimated based on the distance from the anomaly to the seafloor immediately underneath, BF rise height is the best fit rise height based on model results, and CH heat flux and DD heat flux are the best fit heat flux estimates for the chimney case and the diffusive discharge case, respectively. have large instantaneous thermal energies of the order several tens of GW, and if the fluids are brines, such as might have been generated by supercritical phase separation [e.g., Foustoukos and Seyfried, 2007], then they could probably generate a neutral plume layer with a thermal anomaly of 0.07°C at a depth of ∼2500 m. Another possibility is that the plume observed in 2001 was formed at least partly as a result of the explosive discharge of magmatic jets into the water column. Volcaniclastic material attributed to this process blankets the axial valley at 85°E, and a potentially large fraction of the magma erupted during the volcanic event that began in 1999 was explosively discharged .…”

Section: Discussionmentioning

confidence: 99%

Analysis and modeling of hydrothermal plume data acquired from the 85°E segment of the Gakkel Ridge

et al. 2010

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We use data from a CTD plume‐mapping campaign conducted during the Arctic Gakkel Vents (AGAVE) expedition in 2007 to constrain the nature of hydrothermal processes on the Gakkel Ridge at 85°E. Thermal and redox potential (Eh) anomalies were detected in two discrete depth intervals: 2400–2800 m (Interval 1) and 3000–3800 m (Interval 2). The spatial and temporal patterns of the signals indicate that the Interval 1 anomalies were most likely generated by a single large, high‐temperature (T > 100°C) vent field located on the fault terraces that form the NE axial valley wall. In contrast, the Interval 2 anomalies appear to have been generated by up to 7 spatially distinct vent fields associated with constructional volcanic features on the floor of the axial valley, many of which may be sites of diffuse, low‐temperature (T < 10°C) discharge. Numerical simulations of turbulent plumes rising in a weakly stratified Arctic Ocean water column indicate that the high‐temperature field on the axial valley wall has a thermal power of ∼1.8 GW, similar to the Trans‐Atlantic Geotraverse and Rainbow fields in the Atlantic Ocean, whereas the sites on the axial valley floor have values ranging from 5 to 110 MW.

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“…5 reviewed extensively (e.g., see Alt, 1995;Berndt et al, 1988;Bischoff and Rosenbauer, 1985;Fournier, 2007;Foustoukos and Seyfried, 2007;German and Von Damm, 2003;Hanningtion et al, 2005;Hedenquist and Lowenstern, 1994;Heinrich et al, 2004;Henley and Ellis, 1983;Seyfried and Mottl, 1982;Tivey, 2007). The final compositions are a function of many factors including fluid-mineral equilibrium, phase separation, magmatic inputs, mineral precipitation, and mixing.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Subsurface hydrothermal processes and the bioenergetics of chemolithoautotrophy at the shallow-sea vents off Panarea Island (Italy)

et al. 2015

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Please cite this article as: Price, Roy E., LaRowe, Douglas E., Italiano, Francesco, Savov, Ivan, Pichler, Thomas, Amend, Jan P., Subsurface hydrothermal processes and the bioenergetics of chemolithoautotrophy at the shallow-sea vents off Panarea Island (Italy), Chemical Geology (2015Geology ( ), doi: 10.1016Geology ( /j.chemgeo.2015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E DM A N U S C R I P T ACCEPTED MANUSCRIPTThe subsurface evolution of shallow-sea hydrothermal fluids is a function of many factors including fluid-mineral equilibria, phase separation, magmatic inputs, and mineral precipitation, all of which influence discharging fluid chemistry and consequently associated seafloor microbial communities. Shallow-sea vent systems, however, are understudied in this regard. In order to investigate subsurface processes in a shallow-sea hydrothermal vent, and determine how these physical and chemical parameters influence the metabolic potential of the microbial communities, three shallow-sea hydrothermal vents associated with Panarea Island (Italy) were characterized.Vent fluids, pore fluids and gases at the three sites were sampled and analyzed for major and minor elements, redox-sensitive compounds, free gas compositions, and strontium isotopes. The corresponding data were used to 1) describe the subsurface geochemical evolution of the fluids and 2) to evaluate the catabolic potential of 61 inorganic redox reactions for in situ microbial communities. Generally, the vent fluids can be hot (up to 135 °C), acidic (pH 1.9-5.7), and sulfidic (up to 2.5 mM H 2 S). Three distinct types of hydrothermal fluids were identified, each with higher temperatures and lower pH, Mg 2+ and SO 4 2-, relative to seawater. Type 1 was consistently more saline than Type 2, and both were more saline than seawater. Type 3 fluids were similar to or slightly depleted in most major ions relative to seawater. End-member calculations of conservative elements indicate that Type 1 and Type 2 fluids are derived from two different sources, most likely 1) a deeper, higher salinity reservoir and 2) a shallower, lower salinity reservoir, respectively, in a layered hydrothermal system. The deeper reservoir records some of the highest end-member Cl concentrations to date, and developed as a result of recirculation A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

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Fluid Phase Separation Processes in Submarine Hydrothermal Systems

Cited by 84 publications

References 146 publications

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Analysis and modeling of hydrothermal plume data acquired from the 85°E segment of the Gakkel Ridge

Subsurface hydrothermal processes and the bioenergetics of chemolithoautotrophy at the shallow-sea vents off Panarea Island (Italy)

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