@article {McNichol2016a,
	title = {{Assessing microbial processes in deep-sea hydrothermal systems by incubation at in situ temperature and pressure}},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	volume = {115},
	year = {2016},
	pages = {221{\textendash}232},
	abstract = {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.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.dsr.2016.06.011},
	author = {McNichol, J and Sylva, S P and Thomas, F and Taylor, C D and Sievert, S M and Seewald, J S}
}
@article {McDermott2015,
	title = {{Identification of sulfur sources and isotopic equilibria in submarine hot-springs using multiple sulfur isotopes}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {160},
	year = {2015},
	pages = {169{\textendash}187},
	abstract = {Multiple sulfur isotopes were measured in metal sulfide deposits, elemental sulfur, and aqueous hydrogen sulfide to constrain sulfur sources and the isotopic systematics of precipitation in seafloor hydrothermal vents. Areas studied include the Eastern Manus Basin and Lau Basin back-arc spreading centers and the unsedimented basalt-hosted Southern East Pacific Rise (SEPR) and sediment-hosted Guaymas Basin mid-ocean ridge spreading centers. Chalcopyrite and dissolved hydrogen sulfide (H2S) $δ$34S values range from -5.5{\textperthousand} to +5.6{\textperthousand} in Manus Basin samples, +2.4{\textperthousand} to +6.1{\textperthousand} in Lau Basin samples, and +3.7{\textperthousand} to +5.7{\textperthousand} in SEPR samples. Values of $δ$34S for cubic cubanite and H2S range from -1.4{\textperthousand} to +4.7{\textperthousand} in Guaymas Basin samples. Multiple sulfur isotope systematics in fluid-mineral pairs from the SEPR and Lau Basin show that crustal host rock and thermochemical reduction of seawater-derived dissolved sulfate (SO4) are the primary sources of sulfur in mid-ocean ridge and some back-arc systems. At PACMANUS and SuSu Knolls hydrothermal systems in the Eastern Manus Basin, a significant contribution of sulfur is derived from disproportionation of magmatic sulfur dioxide (SO2), while the remaining sulfur is derived from crustal host rocks and SO4 reduction. At the sedimented Guaymas Basin hydrothermal system, sulfur sources include crustal host rock, reduced seawater SO4, and biogenic sulfide. Vent fluid flow through fresher, less-mature sediment supplies an increased quantity of reactant organic compounds that may reduce 34S-enriched SO4, while fluid interaction with more highly-altered sediments results in H2S characterized by a small, but isotopically-significant input of 34S-depleted biogenic sulfides. Near-zero $Δ$33S values in all samples implicate the abiotic processes of SO4 reduction and leaching of host rock as the major contributors to sulfur content at a high temperature unsedimented mid-ocean ridge and at a back-arc system. $Δ$33S values indicate that SO2 disproportionation is an additional process that contributes sulfur to a different back-arc system and to acid spring-type hydrothermal fluid circulation. At the sedimented Guaymus Basin, near-zero $Δ$33S values are also observed, despite negative $δ$34S values that indicate inputs of biogenic pyrite for some samples. In contrast with previous studies reporting isotope disequilibrium between H2S and chalcopyrite, the $δ$34S values of chalcopyrite sampled from the inner 1{\textendash}2 mm of a chimney wall are within {\textpm}1{\textperthousand} of $δ$34S values for H2S in the paired vent fluid, suggesting equilibrium fluid-mineral sulfur isotope exchange at 300{\textendash}400 {\textdegree}C. Isotopic equilibrium between hydrothermal fluid H2S and precipitating chalcopyrite implies that sulfur isotopes in the chalcopyrite lining across a chimney wall may accurately record past hydrothermal activity.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.gca.2015.02.016},
	author = {McDermott, J M and Ono, S and Tivey, M K and Seewald, J S and Shanks, W C}
}
@article {Bennett2013,
	title = {{Trophic regions of a hydrothermal plume dispersing away from an ultramafic-hosted vent-system: Von Damm vent-site, Mid-Cayman Rise}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {14},
	number = {2},
	year = {2013},
	pages = {317{\textendash}327},
	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 $μ$M (background = 43.2 {\textpm} 0.7 $μ$M (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 $μ$M, most likely resulting from the presence of heterotrophic communities, their extracellular products and vent larvae. Elevated carbon concentrations up to 47.4 $μ$M 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.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1525-2027},
	doi = {10.1002/ggge.20063},
	url = {http://dx.doi.org/10.1002/ggge.20063},
	author = {Bennett, S A and Coleman, Max and Huber, J A and Reddington, E and Kinsey, J C and McIntyre, C and Seewald, J S and German, C R}
}
@article {Beinart2012,
	title = {{Evidence for the role of endosymbionts in regional-scale habitat partitioning by hydrothermal vent symbioses}},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {109},
	number = {47},
	year = {2012},
	month = {nov},
	pages = {E3241{\textendash}E3250},
	abstract = {Deep-sea hydrothermal vents are populated by dense communities of animals that form symbiotic associations with chemolithoautotrophic bacteria. To date, our understanding of which factors govern the distribution of host/symbiont associations (or holobionts) in nature is limited, although host physiology often is invoked. In general, the role that symbionts play in habitat utilization by vent holobionts has not been thoroughly addressed. Here we present evidence for symbiont-influenced, regional-scale niche partitioning among symbiotic gastropods (genus Alviniconcha) in the Lau Basin. We extensively surveyed Alviniconcha holobionts from four vent fields using quantitative molecular approaches, coupled to characterization of high-temperature and diffuse vent-fluid composition using gastight samplers and in situ electrochemical analyses, respectively. Phylogenetic analyses exposed cryptic host and symbiont diversity, revealing three distinct host types and three different symbiont phylotypes (one $ε$-proteobacteria and two $\gamma$-proteobacteria) that formed specific associations with one another. Strikingly, we observed that holobionts with $ε$-proteobacterial symbionts were dominant at the northern fields, whereas holobionts with $\gamma$-proteobacterial symbionts were dominant in the southern fields. This pattern of distribution corresponds to differences in the vent geochemistry that result from deep subsurface geological and geothermal processes. We posit that the symbionts, likely through differences in chemolithoautotrophic metabolism, influence niche utilization among these holobionts. The data presented here represent evidence linking symbiont type to habitat partitioning among the chemosynthetic symbioses at hydrothermal vents and illustrate the coupling between subsurface geothermal processes and niche availability.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1202690109},
	author = {Beinart, R A and Sanders, J G and Faure, B and Sylva, S P and Lee, R W and Becker, E L and Gartman, A and Luther, G W and Seewald, J S and Fisher, C R and Girguis, P R}
}
@article {Pester2012,
	title = {{Subseafloor phase equilibria in high-temperature hydrothermal fluids of the Lucky Strike Seamount (Mid-Atlantic Ridge, 37{\textdegree}17{\textquoteright}N)}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {90},
	year = {2012},
	pages = {303{\textendash}322},
	abstract = {As part of an integrated study conducted at the Lucky Strike Seamount (Mid-Atlantic Ridge, 37{\textdegree}17'N) in 2008, gas-tight sampling devices were used to collect high-temperature (\~{}300~{\textdegree}C) hydrothermal fluids issuing from sulfide structures distributed throughout the vent field located in the summit depression. Compared with previous observations from 1993 to 1997, the most substantial changes in vent fluid compositions are dramatically increased CO2 concentrations (\~{}5{\texttimes}, up to 133~mmol/L) and the observation of vent fluids enriched in dissolved chloride relative to seawater. Combined with an increase in $δ$13CCO2$δ$13CCO2 values by \~{}4{\textperthousand} in 2008, the elevated CO2 indicates replenishment of the magmatic heat source and may be indicative of a recent magmatic event. The additional supporting fluid chemistry is, however, similar to that of the previous sampling intervals, necessitating a reassessment of the subseafloor controls on vent fluid chemistry at Lucky Strike in the context of recently obtained geophysical data that provides the depth/extent of a steady-state magma chamber. Two-phase behavior is indicated by the chloride variability in the vent fluids; and comparison with experimental data for the associated chloride-dependent partitioning of minor/trace elements suggests the possibility of a similar source fluid for all the vent structures, while limiting the likelihood of shallow phase separation and subseafloor mixing for the hydrothermal end-members. A recently calibrated Fe/Mn geothermometer indicates minimum subseafloor equilibration temperatures of 350{\textendash}385~{\textdegree}C. However, constraints imposed by dissolved Si/Cl in conjunction with geophysical observations are consistent with peak reaction conditions at temperatures of 430{\textendash}475~{\textdegree}C and pressures near the top of the axial magma chamber (\~{}410{\textendash}480~bars), where magmatic CO2 becomes entrained in the circulating fluids. The distance between the magma chamber and the seafloor at Lucky Strike is substantially greater than at most faster spreading ridges; and we propose the resulting increased residence time in the up-flow zone leads to the re-equilibration of temperature sensitive transition metals at conditions less extreme than those associated with peak reaction. Agreement between experimental data, thermodynamic model calculations, and dissolved concentrations of Fe, Cu, Zn, H2, and H2S in the Lucky Strike fluids reinforce the hypothesis of pH-redox equilibria for transition metals at relatively oxidizing conditions and temperatures predicted by the empirical Fe/Mn geothermometer. In-situ pH measurements of the high-temperature fluids exiting the seafloor are also consistent with the model calculations.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.gca.2012.05.018},
	url = {http://dx.doi.org/10.1016/j.gca.2012.05.018},
	author = {Pester, N J and Reeves, E P and Rough, M E and Ding, K and Seewald, J S and Seyfried, W E}
}
@article {Mottl2011,
	title = {{Chemistry of hot springs along the Eastern Lau Spreading Center}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {75},
	number = {4},
	year = {2011},
	pages = {1013{\textendash}1038},
	abstract = {The Eastern Lau Spreading Center (ELSC) is the southernmost part of the back-arc spreading axis in the Lau Basin, west of the Tonga trench and the active Tofua volcanic arc. Over its 397-km length it exhibits large and systematic changes in spreading rate, magmatic/tectonic processes, and proximity to the volcanic arc. In 2005, we collected 81 samples of vent water from six hydrothermal fields along the ELSC. The chemistry of these waters varies both within and between vent fields, in response to changes in substrate composition, temperature and pressure, pH, water/rock ratio, and input from magmatic gases and subducted sediment. Hot-spring temperatures range from 229{\textdegree} to 363~{\textdegree}C at the five northernmost fields, with a general decrease to the south that is reversed at the Mariner field. The southernmost field, Vai Lili, emitted water at up to 334~{\textdegree}C in 1989 but had a maximum venting temperature of only 121~{\textdegree}C in 2005, due to waning activity and admixture of bottom seawater into the subseafloor plumbing system. Chloride varies both within fields and from one field to another, from a low of 528~mmol/kg to a high of 656~mmol/kg, and may be enriched by phase separation and/or leaching of Cl from the rock. Concentrations of the soluble elements K, Rb, Cs, and B likewise increase southward as the volcanic substrate becomes more silica-rich, especially on the Valu Fa Ridge. Iodine and $δ$7Li increase southward, and $δ$11B decreases as B increases, apparently in response to increased input from subducted sediment as the arc is approached. Species that decrease southward as temperature falls are Si, H2S, Li, Na/Cl, Fe, Mn, and 87Sr/86Sr, whereas pH, alkalinity, Ca, and Sr increase. Oxygen isotopes indicate a higher water/rock ratio in the three systems on Valu Fa Ridge, consistent with higher porosity in more felsic volcanic rocks. Vent waters at the Mariner vent field on the Valu Fa Ridge are significantly hotter, more acid and metal-rich, less saline, and richer in dissolved gases and other volatiles, including H2S, CO2, and F, than the other vent fields, consistent with input of magmatic gases. The large variations in geologic and geophysical parameters produced by back-arc spreading along the ELSC, which exceed those along mid-ocean ridge spreading axes, produce similar large variations in the composition of vent waters, and thus provide new insights into the processes that control the chemistry of submarine hot springs.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2010.12.008},
	url = {http://dx.doi.org/10.1016/j.gca.2010.12.008},
	author = {Mottl, M J and Seewald, J S and Wheat, C G and Tivey, M K and Michael, P J and Proskurowski, G and McCollom, T M and Reeves, E and Sharkey, J and You, C F and Chan, L H and Pichler, T}
}
@article {Reeves2011,
	title = {{Geochemistry of hydrothermal fluids from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {75},
	number = {4},
	year = {2011},
	pages = {1088{\textendash}1123},
	abstract = {Processes controlling the composition of seafloor hydrothermal fluids in silicic back-arc or near-arc crustal settings remain poorly constrained despite growing evidence for extensive magmatic{\textendash}hydrothermal activity in such environments. We conducted a survey of vent fluid compositions from two contrasting sites in the Manus back-arc basin, Papua New Guinea, to examine the influence of variations in host rock composition and magmatic inputs (both a function of arc proximity) on hydrothermal fluid chemistry. Fluid samples were collected from felsic-hosted hydrothermal vent fields located on Pual Ridge (PACMANUS and Northeast (NE) Pual) near the active New Britain Arc and a basalt-hosted vent field (Vienna Woods) located farther from the arc on the Manus Spreading Center. Vienna Woods fluids were characterized by relatively uniform endmember temperatures (273{\textendash}285~{\textdegree}C) and major element compositions, low dissolved CO2 concentrations (4.4~mmol/kg) and high measured pH (4.2{\textendash}4.9 at 25~{\textdegree}C). Temperatures and compositions were highly variable at PACMANUS/NE Pual and a large, newly discovered vent area (Fenway) was observed to be vigorously venting boiling (358~{\textdegree}C) fluid. All PACMANUS fluids are characterized by negative $δ$DH2O$δ$DH2O values, in contrast to positive values at Vienna Woods, suggesting substantial magmatic water input to circulating fluids at Pual Ridge. Low measured pH (25~{\textdegree}C) values (\~{}2.6{\textendash}2.7), high endmember CO2 (up to 274~mmol/kg) and negative $δ$34SH2S$δ$34SH2S values (down to -2.7{\textperthousand}) in some vent fluids are also consistent with degassing of acid-volatile species from evolved magma. Dissolved CO2 at PACMANUS is more enriched in 13C (-4.1{\textperthousand} to -2.3{\textperthousand}) than Vienna Woods (-5.2{\textperthousand} to -5.7{\textperthousand}), suggesting a contribution of slab-derived carbon. The mobile elements (e.g. Li, K, Rb, Cs and B) are also greatly enriched in PACMANUS fluids reflecting increased abundances in the crust there relative to the Manus Spreading Center. Variations in alkali and dissolved gas abundances with Cl at PACMANUS and NE Pual suggest that phase separation has affected fluid chemistry despite the low temperatures of many vents. In further contrast to Vienna Woods, substantial modification of PACMANUS/NE Pual fluids has taken place as a result of seawater ingress into the upflow zone. Consistently high measured Mg concentrations as well as trends of increasingly non-conservative SO4 behavior, decreasing endmember Ca/Cl and Sr/Cl ratios with increased Mg indicate extensive subsurface anhydrite deposition is occurring as a result of subsurface seawater entrainment. Decreased pH and endmember Fe/Mn ratios in higher Mg fluids indicate that the associated mixing/cooling gives rise to sulfide deposition and secondary acidity production. Several low temperature (⩽80~{\textdegree}C) fluids at PACMANUS/NE Pual also show evidence for anhydrite dissolution and water{\textendash}rock interaction (fixation of B) subsequent to seawater entrainment. Hence, the evolution of fluid compositions at Pual Ridge reflects the cumulative effects of water/rock interaction, admixing and reaction of fluids exsolved from silicic magma, phase separation/segregation and seawater ingress into upflow zones.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2010.11.008},
	url = {http://dx.doi.org/10.1016/j.gca.2010.11.008},
	author = {Reeves, E and Seewald, J S and Saccocia, P J and Walsh, E and Bach, W and Craddock, P R and Shanks, W C and Sylva, S P and Pichler, T and Rosner, M}
}
@article {German2010,
	title = {{Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise}},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {107},
	number = {32},
	year = {2010},
	month = {aug},
	pages = {14020{\textendash}14025},
	abstract = {Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global mid-ocean ridge remains unexplored for hydrothermal activity. Of particular interest are the world{\textquoteright}s ultraslow spreading ridges that were the last to be demonstrated to host high-temperature venting but may host systems particularly relevant to prebiotic chemistry and the origins of life. Here we report evidence for previously unknown, diverse, and very deep hydrothermal vents along the similar to 110 km long, ultraslow spreading Mid-Cayman Rise (MCR). Our data indicate that the MCR hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultramafic systems and, at similar to 5,000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent types identified here and their relative geographic isolation make the MCR unique in the oceans. These new sites offer prospects for an expanded range of vent-fluid compositions, varieties of abiotic organic chemical synthesis and extremophile microorganisms, and unparalleled faunal biodiversity-all in close proximity.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1009205107},
	author = {German, C R and Bowen, A and Coleman, M L and Honig, D L and Huber, J A and Jakuba, M V and Kinsey, J C and Kurz, M D and Leroy, S and McDermott, J M and de Lepinay, B M and Nakamura, K and Seewald, J S and Smith, J L and Sylva, S P and Van Dover, C L and Whitcomb, L L and Yoerger, D R}
}
@article {Cruse2010,
	title = {{Low-molecular weight hydrocarbons in vent fluids from the Main Endeavour Field, northern Juan de Fuca Ridge}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {74},
	number = {21},
	year = {2010},
	pages = {6126{\textendash}6140},
	abstract = {Despite its location on sediment-free basalt, vent fluids from the Main Endeavour Field (MEF) contain chemical species that indicate fluids have interacted with sediments during circulation. We report on the distribution and isotopic abundances of organic compounds (C1{\textendash}C3 alkanes and alkenes, benzene and toluene) in fluids collected from the Main Endeavour Field (MEF) in July, 2000, to understand the processes that regulate their abundances and characterize fluid sources. Aqueous organic compounds are derived from the thermal alteration of sedimentary organic matter and subsequently undergo further oxidation reactions during fluid flow. Fluid:sediment mass ratios calculated using $Σ$NH4 concentrations indicate that the sediments are distal to the MEF, resulting in a common reservoir of fluids for all of the vents. Following the generation from sediment alteration, aqueous organic compounds undergo secondary alteration reactions via a stepwise oxidation reaction mechanism. Alkane distributions and isotopic compositions indicate that organic compounds in MEF fluids have undergone a greater extent of alteration as compared to Middle Valley fluids, either due to differences in subsurface redox conditions or the residence time of fluids at subsurface conditions. The distributions of the aromatic compounds benzene and toluene are qualitatively consistent with the subsurface conditions indicated by equilibration of aqueous alkanes and alkanes. However, benzene and toluene do not achieve chemical equilibrium in the subsurface. Methane and CO2 also do not equilibrate chemically or isotopically at reaction zone temperatures, a likely result of an insufficient reaction time after addition of CO2 from magmatic sources during upflow. The organic geochemistry supports the assumption that the sediments with which MEF fluids interact has the same composition as sediments present in Middle Valley itself, and highlight differences in subsurface reaction zone conditions and fluid flow pathways at these two sites.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2010.07.013},
	url = {http://dx.doi.org/10.1016/j.gca.2010.07.013},
	author = {Cruse, A M and Seewald, J S}
}
@article {Craddock2010a,
	title = {{Rare earth element abundances in hydrothermal fluids from the Manus Basin, Papua New Guinea: indicators of sub-seafloor hydrothermal processes in back-arc basins}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {74},
	number = {19},
	year = {2010},
	pages = {5494{\textendash}5513},
	abstract = {Rare earth element (REE) concentrations are reported for a large suite of seafloor vent fluids from four hydrothermal systems in the Manus back-arc basin (Vienna Woods, PACMANUS, DESMOS and SuSu Knolls vent areas). Sampled vent fluids show a wide range of absolute REE concentrations and chondrite-normalized (REEN) distribution patterns (LaN /SmN \~{} 0.6{\textendash}11; LaN /YbN \~{} 0.6 {\textendash} 71; View the MathML sourceEuN/EuN*\~{}1{\textendash}55). REEN distribution patterns in different vent fluids range from light-REE enriched, to mid- and heavy-REE enriched, to flat, and have a range of positive Eu-anomalies. This heterogeneity contrasts markedly with relatively uniform REEN distribution patterns of mid-ocean ridge hydrothermal fluids. In Manus Basin fluids, aqueous REE compositions do not inherit directly or show a clear relationship with the REE compositions of primary crustal rocks with which hydrothermal fluids interact. These results suggest that the REEs are less sensitive indicators of primary crustal rock composition despite crustal rocks being the dominant source of REEs in submarine hydrothermal fluids. In contrast, differences in aqueous REE compositions are consistently correlated with differences in fluid pH and ligand (chloride, fluoride and sulfate) concentrations. Our results suggest that the REEs can be used as an indicator of the type of magmatic acid volatile (i.e., presence of HF, SO2) degassing in submarine hydrothermal systems. Additional fluid data suggest that near-seafloor mixing between high-temperature hydrothermal fluid and locally entrained seawater at many vent areas in the Manus Basin causes anhydrite precipitation. Anhydrite effectively incorporates REE and likely affects measured fluid REE concentrations, but does not affect their relative distributions.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2010.07.003},
	url = {http://dx.doi.org/10.1016/j.gca.2010.07.003},
	author = {Craddock, P R and Bach, W and Seewald, J S and Rouxel, O J and Reeves, E and Tivey, M K}
}
@inbook {Cruse2008,
	title = {{Hydrothermal fluid composition at Middle Valley, northern Juan de Fuca Ridge: temporal and spatial variability}},
	booktitle = {Magma to microbe : modeling hydrothermal processes at ocean spreading centers},
	series = {Geophysical Monograph},
	number = {178},
	year = {2008},
	pages = {145{\textendash}166},
	publisher = {American Geophysical Union},
	organization = {American Geophysical Union},
	address = {Washington, DC},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	isbn = {0875904432},
	doi = {10.1029/178GM08},
	url = {http://dx.doi.org/10.1029/178GM08},
	author = {Cruse, A M and Seewald, J S and Saccocia, P J and Zierenberg, R},
	editor = {Lowell, R P}
}
@article {Cruse2006,
	title = {{Geochemistry of low-molecular weight hydrocarbons in hydrothermal fluids from Middle Valley, northern Juan de Fuca Ridge}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {70},
	number = {8},
	year = {2006},
	pages = {2073{\textendash}2092},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2006.01.015},
	url = {http://dx.doi.org/10.1016/j.gca.2006.01.015},
	author = {Cruse, A M and Seewald, J S}
}
@article {Pearson2005,
	title = {{Bacterial incorporation of relict carbon in the hydrothermal environment of Guaymas Basin}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {69},
	number = {23},
	year = {2005},
	pages = {5477{\textendash}5486},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2005.07.007},
	url = {http://dx.doi.org/10.1016/j.gca.2005.07.007},
	author = {Pearson, A and Seewald, J S and Eglinton, T I}
}
@article {Seewald2003,
	title = {{Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca ridge: Temporal variability following earthquake activity}},
	journal = {Earth and Planetary Science Letters},
	volume = {216},
	number = {4},
	year = {2003},
	pages = {575{\textendash}590},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0012-821X},
	doi = {10.1016/S0012-821X(03)00543-0},
	url = {http://dx.doi.org/10.1016/S0012-821X(03)00543-0},
	author = {Seewald, J S and Cruse, A M and Saccocia, P J}
}
@article {Seyfried2003,
	title = {{Chemistry of hydrothermal vent fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: Geochemical controls in the aftermath of June 1999 seismic events}},
	journal = {Journal of Geophysical Research},
	volume = {108},
	number = {B9},
	year = {2003},
	pages = {Article no. 2429},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0148-0227},
	doi = {10.1029/2002JB001957},
	url = {http://dx.doi.org/10.1029/2002JB001957},
	author = {Seyfried, W E and Seewald, J S and Berndt, M E and Ding, K and Foustoukos, D}
}
@article {Haymon1991,
	title = {{Active eruption seen on East Pacific Rise}},
	journal = {EOS, Transactions, American Geophysical Union},
	volume = {72},
	number = {46},
	year = {1991},
	pages = {505,507},
	issn = {0096-3941},
	doi = {10.1029/90EO00362},
	url = {http://dx.doi.org/10.1029/90EO00362},
	author = {Haymon, R M and Carbotte, S and Wright, D and Beedle, N and Johnson, F and Fornari, D J and Von Damm, K L and Grebmeier, J and Lilley, M and McLaughlin, E and Olson, E and Edmond, J and Perfit, M R and Smith, M and Shanks, W C and Lutz, R and Seewald, J S and Reudelhuber, D}
}
@article {Haymon1991b,
	title = {{EPR crest erupts north of Leg 142 drillsite}},
	journal = {JOI/USSAC Newsletter},
	volume = {4},
	number = {3},
	year = {1991},
	pages = {4{\textendash}5},
	author = {Haymon, R and Fornari, D J and Von Damm, K L and Edmond, J and Lilley, M and Perfit, M and Shanks, W C and Grebmeier, J and Lutz, R and Carbotte, S and Wright, D and Smith, M and Laughlin, E and Beedle, N and Seewald, J S and Reudelhuber, D and Olson, E and Johnson, F}
}
