@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 {Wheat2008,
	title = {{Borehole observations of fluid flow from South Chamorro Seamount, an active serpentinite mud volcano in the Mariana forearc}},
	journal = {Earth and Planetary Science Letters},
	volume = {267},
	number = {3-4},
	year = {2008},
	pages = {401{\textendash}409},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2007.11.057},
	url = {http://dx.doi.org/10.1016/j.epsl.2007.11.057},
	author = {Wheat, C G and Fryer, P and Fisher, A T and Hulme, S and Jannasch, H W and Mottl, M J}
}
@article {Walker2008,
	title = {{Dissolved inorganic carbon isotopic composition of low-temperature axial and ridge-flank hydrothermal fluids of the Juan de Fuca Ridge}},
	journal = {Marine Chemistry},
	volume = {108},
	number = {1-2},
	year = {2008},
	pages = {123{\textendash}136},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0304-4203},
	doi = {10.1016/j.marchem.2007.11.002},
	url = {http://dx.doi.org/10.1016/j.marchem.2007.11.002},
	author = {Walker, B D and McCarthy, M D and Fisher, A T and Guilderson, T P}
}
