Hydrothermal Processes

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

doi:10.1016/b0-08-043751-6/06109-0

Cited by 209 publications

(178 citation statements)

References 155 publications

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“…Measured temperatures, pH (25C) and endmember fluid composition have remained relatively constant since previous expeditions in 1990 and 1995 (Lisitsyn et al, 1993;Auzende et al, 1996;Gamo et al, 1997;Douville et al, 1999;Fourre et al, 2006). In general, almost all aspects of the chemistry of fluids venting at Vienna Woods are similar to observations from basalt-hosted hydrothermal systems in MOR settings (Von Damm, 1995;German and Von Damm, 2003).…”

Section: Temperaturesupporting

confidence: 64%

“…pH (25°) values were used for all calculations. Most in situ pH values for high temperature fluids are up to 1 pH unit higher (GERMAN and VON DAMM, 2003). However, this has no effect on predicted CH 3 SH abundance for any of the fluids presented here.…”

Section: Discussionmentioning

confidence: 76%

“…The highest CO 2 concentrations, found in the lower Cl fluids at Snowcap and Satanic Mills (Fig. 5.5b, Table 5.2), are among the highest reported to date for vent fluids (Karl et al, 1988;Butterfield et al, 1990;Sakai et al, 1990a,b;Von Damm, 1995;German and Von Damm, 2003;Lupton et al, 2006) and are comparable to those observed in black smoker fluids at the back-arc JADE site, Okinawa Trough (Sakai et al, 1990b). In addition to the higher concentrations relative to Vienna Woods, CO 2 is more 13 C-enriched at PACMANUS, with endmember δ 13 C CO2 values varying from -4.1‰ to -2.3‰ (Table 5.2).…”

Section: H 2 H 2 S Ch 4 Co and Comentioning

confidence: 90%

“…In general, endmember concentrations of H 2 , H 2 S, CH 4 and CO 2 in Vienna Woods fluids are uniform and relatively low compared to the known range of MOR fluid compositions (Von Damm, 1995;German and Von Damm, 2003). At Pual Ridge, however, significant variability is evident in endmember H 2 , H 2 S, CH 4 and CO 2 both between vent areas and within each area (Table 5.2).…”

Section: H 2 H 2 S Ch 4 Co and Comentioning

confidence: 95%

“…At all PACMANUS areas, endmember CH 4 concentrations are at the lower end of known compositions from MOR systems (German and Von Damm, 2003) but highly variable, ranging from 13.5μM at Fenway (F2) to a maximum of 78.1μM at Snowcap (SC2). Highest endmember CH 4 concentrations are also evident in fluids with lower Cl contents (Fig.…”

Section: H 2 H 2 S Ch 4 Co and Comentioning

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: Temperaturesupporting

confidence: 64%

Section: Discussionmentioning

confidence: 76%

Section: H 2 H 2 S Ch 4 Co and Comentioning

confidence: 90%

Section: H 2 H 2 S Ch 4 Co and Comentioning

confidence: 95%

Section: H 2 H 2 S Ch 4 Co and Comentioning

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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Understanding a submarine eruption through time series hydrothermal plume sampling of dissolved and particulate constituents: West Mata, 2008–2012

Baumberger

Lilley

Resing

et al. 2014

Geochem Geophys Geosyst

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Four cruises between 2008 and 2012 monitored the continuing eruption of West Mata volcano in the NE Lau Basin as it produced plumes of chemically altered water above its summit. Although large enrichments in 3 He, CO 2 , Fe, and Mn were observed in the plumes, the most notable enrichment was that of H 2 , which reached concentrations as high as 14,843 nM. Strongly enriched H 2 concentrations in the water column result from reactions between seawater or magmatic water and extremely hot rocks. In 2008, the observation of elevated H 2 concentrations in the water column above West Mata pointed to vigorous ongoing eruptions at the volcano's summit. The eruption was confirmed by visual observations made by the ROV Jason 2 in 2009 and demonstrated that H 2 measurements are a vital instrument to detect ongoing volcanic eruptions at the seafloor. Elevated H 2 in 2010 showed that the eruption was ongoing, although at a reduced level given a maximum H 2 concentration of 4410 nM. In 2012, H 2 levels in the water column declined significantly, to a maximum of only 7 nM, consistent with visual observations from the Quest-4000 ROV that found no evidence of an ongoing volcanic eruption. Methane behaved independently of other measured gases and its concentrations in the hydrothermal plume were very low. We attribute its minimal enrichments to a mixture of mantle carbon reduced to CH 4 and biological CH 4 from diffuse flow sites. This study demonstrates that ongoing submarine volcanic eruptions are characterized by high dissolved H 2 concentrations present in the overlying water column.

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Particle dynamics in the rising plume at Piccard Hydrothermal Field, Mid‐Cayman Rise

Estapa

Breier

German

2015

Geochem Geophys Geosyst

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Processes active in rising hydrothermal plumes, such as precipitation, particle aggregation, and biological growth, affect particle size distributions and can exert important influences on the biogeochemical impact of submarine venting of iron to the oceans and their sediments. However, observations to date of particle size distribution within these systems are both limited and conflicting. In a novel buoyant hydrothermal plume study at the recently discovered high-temperature (3988C) Piccard Hydrothermal Field, MidCayman Rise, we report optical measurements of particle size distributions (PSDs). We describe the plume PSD in terms of a simple, power-law model commonly used in studies of upper and coastal ocean particle dynamics. Observed PSD slopes, derived from spectral beam attenuation and laser diffraction measurements, are among the highest found to date anywhere in the ocean and ranged from 2.9 to 8.5. Beam attenuation at 650 nm ranged from near zero to a rarely observed maximum of 192 m 21 at 3.5 m above the vent. We did not find large (>100 lm) particles that would settle rapidly to the sediments. Instead, beam attenuation was well-correlated to total iron, suggesting the first-order importance of particle dilution, rather than precipitation or dissolution, in the rising plume at Piccard. Our observations at Piccard caution against the assumption of rapid deposition of hydrothermal, particulate metal fluxes, and illustrate the need for more particle size and composition measurements across a broader range of sites, globally.

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Hydrothermal Processes

Cited by 209 publications

References 155 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

Understanding a submarine eruption through time series hydrothermal plume sampling of dissolved and particulate constituents: West Mata, 2008–2012

Particle dynamics in the rising plume at Piccard Hydrothermal Field, Mid‐Cayman Rise

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