@article {Neira2016,
	title = {{Cross-hole tracer experiment reveals rapid fluid flow and low effective porosity in the upper oceanic crust}},
	journal = {Earth and Planetary Science Letters},
	volume = {450},
	year = {2016},
	pages = {355{\textendash}365},
	abstract = {Numerous field, laboratory, and modeling studies have explored the flows of fluid, heat, and solutes during seafloor hydrothermal circulation, but it has been challenging to determine transport rates and flow directions within natural systems. Here we present results from the first cross-hole tracer experiment in the upper oceanic crust, using four subseafloor borehole observatories equipped with autonomous samplers to track the transport of a dissolved tracer (sulfur hexafluoride, SF6) injected into a ridge-flank hydrothermal system. During the first three years after tracer injection, SF6 was transported both north and south through the basaltic aquifer. The observed tracer transport rate of \~{}2{\textendash}3 m/day is orders of magnitude greater than bulk rates of flow inferred from thermal and chemical observations and calculated with coupled fluid-heat flow simulations. Taken together, these results suggest that the effective porosity of the upper volcanic crust through which much tracer was transported is {\textless}1{\%}, with fluid flowing rapidly along a few well-connected channels. This is consistent with the heterogeneous (layered, faulted, and/or fractured) nature of the volcanic upper oceanic crust.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.epsl.2016.06.048},
	author = {Neira, N M and Clark, J F and Fisher, A T and Wheat, C G and Haymon, R M and Becker, K}
}
@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 {Fueri2010,
	title = {{Carbon release from submarine seeps at the Costa Rica fore arc: Implications for the volatile cycle at the Central America convergent margin}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {11},
	year = {2010},
	pages = {Q04S21},
	abstract = {We report total dissolved inorganic carbon (DIC) abundances and isotope ratios, as well as helium isotope ratios (3He/4He), of cold seep fluids sampled at the Costa Rica fore arc in order to evaluate the extent of carbon loss from the submarine segment of the Central America convergent margin. Seep fluids were collected over a 12 month period at Mound 11, Mound 12, and Jaco Scar using copper tubing attached to submarine flux meters operating in continuous pumping mode. The fluids show minimum 3He/4He ratios of 1.3 RA (where RA is air 3He/4He), consistent with a small but discernable contribution of mantle-derived helium. At Mound 11, $δ$13C∑CO2 values between -23.9{\textperthousand} and -11.6{\textperthousand} indicate that DIC is predominantly derived from deep methanogenesis and is carried to the surface by fluids derived from sediments of the subducting slab. In contrast, at Mound 12, most of the ascending dissolved methane is oxidized due to lower flow rates, giving extremely low $δ$13C∑CO2 values ranging from -68.2{\textperthousand} to -60.3{\textperthousand}. We estimate that the carbon flux (CO2 plus methane) through submarine fluid venting at the outer fore arc is 8.0 {\texttimes} 105 g C km-1 yr-1, which is virtually negligible compared to the total sedimentary carbon input to the margin and the output at the volcanic front. Unless there is a significant but hitherto unidentified carbon flux at the inner fore arc, the implication is that most of the carbon being subducted in Costa Rica must be transferred to the (deeper) mantle, i.e., beyond the depth of arc magma generation.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2009GC002810},
	url = {http://dx.doi.org/10.1029/2009GC002810},
	author = {Fueri, E and Hilton, D R and Tryon, M D and Brown, K M and McMurtry, G M and Brueckmann, W and Wheat, C G}
}
@article {Mottl2004,
	title = {{Chemistry of springs across the Mariana forearc shows progressive devolatilization of the subducting plate}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {68},
	number = {23},
	year = {2004},
	pages = {4915{\textendash}4933},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2004.05.037},
	url = {http://dx.doi.org/10.1016/j.gca.2004.05.037},
	author = {Mottl, M A and Wheat, C G and Fryer, P and Gharib, J and Martin, J B}
}
@article {Wheat2000,
	title = {{Composition of pore and spring waters from Baby Bare: Global implications of geochemical fluxes from a ridge flank hydrothermal system}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {64},
	number = {4},
	year = {2000},
	pages = {629{\textendash}642},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/S0016-7037(99)00347-6},
	url = {http://dx.doi.org/10.1016/S0016-7037(99)00347-6},
	author = {Wheat, C G and Mottl, M J}
}
@article {Lupton1993,
	title = {{Chemical and physical diversity of hydrothermal plumes along the East Pacific Rise, 8 degrees 45{\textquoteright} N to 11 degrees 50{\textquoteright} N}},
	journal = {Geophysical Research Letters},
	volume = {20},
	number = {24},
	year = {1993},
	pages = {2913{\textendash}2916},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0094-8276},
	doi = {10.1029/93GL00906},
	url = {http://dx.doi.org/10.1029/93GL00906},
	author = {Lupton, J E and Baker, E T and Mottl, M J and Sansone, F J and Wheat, C G and Resing, J A and Massoth, G J and Measures, C I and Feely, R A}
}
