@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 {Smith2011,
	title = {{In situ enrichment of ocean crust microbes on igneous minerals and glasses using an osmotic flow-through device}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {12},
	year = {2011},
	pages = {Q06007},
	abstract = {The Integrated Ocean Drilling Program (IODP) Hole 1301A on the eastern flank of Juan de Fuca Ridge was used in the first long-term deployment of microbial enrichment flow cells using osmotically driven pumps in a subseafloor borehole. Three novel osmotically driven colonization systems with unidirectional flow were deployed in the borehole and incubated for 4 years to determine the microbial colonization preferences for 12 minerals and glasses present in igneous rocks. Following recovery of the colonization systems, we measured cell density on the minerals and glasses by fluorescent staining and direct counting and found some significant differences between mineral samples. We also determined the abundance of mesophilic and thermophilic culturable organotrophs grown on marine R2A medium and identified isolates by partial 16S or 18S rDNA sequencing. We found that nine distinct phylotypes of culturable mesophilic oligotrophs were present on the minerals and glasses and that eight of the nine can reduce nitrate and oxidize iron. Fe(II)-rich olivine minerals had the highest density of total countable cells and culturable organotrophic mesophiles, as well as the only culturable organotrophic thermophiles. These results suggest that olivine (a common igneous mineral) in seawater-recharged ocean crust is capable of supporting microbial communities, that iron oxidation and nitrate reduction may be important physiological characteristics of ocean crust microbes, and that heterogeneously distributed minerals in marine igneous rocks likely influence the distribution of microbial communities in the ocean crust.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2010GC003424},
	url = {http://dx.doi.org/10.1029/2010GC003424},
	author = {Smith, A and Popa, R and Fisk, M and Nielsen, M and Wheat, C G and Jannasch, H W and Fisher, A T and Becker, K and Sievert, S M and Flores, G}
}
@article {Wheat2004a,
	title = {{Heat flow through a basaltic outcrop on a sedimented young ridge flank}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {5},
	year = {2004},
	pages = {Article no. Q12006},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2004GC000700},
	url = {http://dx.doi.org/10.1029/2004GC000700},
	author = {Wheat, C G and Mottl, M J and Fisher, A T and Kadko, D and Davis, E E and Baker, E T and Mullineaux, L S and Peterson, C H and Micheli, F and Mills, S W}
}
