@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 {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}
}
