@article {Thal2016,
	title = {{Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano}},
	journal = {Journal of Volcanology and Geothermal Research},
	volume = {323},
	year = {2016},
	pages = {80{\textendash}96},
	abstract = {North Su is a double-peaked active andesite submarine volcano located in the eastern Manus Basin of the Bismarck Sea that reaches a depth of 1154 m. It hosts a vigorous and varied hydrothermal system with black and white smoker vents along with several areas of diffuse venting and deposits of native sulfur. Geologic mapping based on ROV observations from 2006 and 2011 combined with morphologic features identified from repeated bathymetric surveys in 2002 and 2011 documents the emplacement of a volcanic cryptodome between 2006 and 2011. We use our observations and rock analyses to interpret an eruption scenario where highly viscous, crystal-rich andesitic magma erupted slowly into the water-saturated, gravel-dominated slope of North Su. An intense fragmentation process produced abundant blocky clasts of a heterogeneous magma (olivine crystals within a rhyolitic groundmass) that only rarely breached through the clastic cover onto the seafloor. Phreatic and phreatomagmatic explosions beneath the seafloor cause mixing of juvenile and pre-existing lithic clasts and produce a volcaniclastic deposit. This volcaniclastic deposit consists of blocky, non-altered clasts next, variably (1{\textendash}100{\%}) altered clasts, hydrothermal precipitates and crystal fragments. The usually applied parameters to identify juvenile subaqueous lava fragments, i.e. fluidal shape or chilled margin, were not applicable to distinguish between pre-existing non-altered clasts and juvenile clasts. This deposit is updomed during further injection of magma and mechanical disruption. Gas-propelled turbulent clast-recycling causes clasts to develop variably rounded shapes. An abundance of blocky clasts and the lack of clasts typical for the contact of liquid lava with water is interpreted to be the result of a cooled, high-viscosity, crystal-rich magma that failed as a brittle solid upon stress. The high viscosity allows the lava to form blocky and short lobes. The pervasive volcaniclastic cover on North Su is partly cemented by hydrothermal precipitates. These hydrothermally-cemented breccias, crusts and single pillars show that hydrothermal circulation through a thick layer of volcaniclastic deposits can temporarily increase slope stability through precipitation and cementation.},
	keywords = {AUV ABE (Autonomous Benthic Explorer), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.jvolgeores.2016.04.041},
	author = {Thal, J and Tivey, M A and Yoerger, D R and Bach, W}
}
@article {Tivey2014,
	title = {{High-resolution near-bottom vector magnetic anomalies over Raven Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge}},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {10},
	year = {2014},
	pages = {7389{\textendash}7403},
	abstract = {High-resolution, near-bottom vector magnetic data were collected by remotely operated vehicle Jason over the Raven hydrothermal vent field (47{\textdegree}57.3'N 129{\textdegree}5.75'W) located north of Main Endeavour vent field on the Endeavour segment of the Juan de Fuca Ridge. The survey was part of a comprehensive heat flow study of the Raven site using innovative thermal blanket technology to map the heat flux and crustal fluid pathways around a solitary hydrothermal vent field. Raven hydrothermal activity is presently located along the western axial valley wall, while additional inactive hydrothermal deposits are found to the NW on the upper rift valley wall. Magnetic inversion results show discrete areas of reduced magnetization associated with both active and inactive hydrothermal vent deposits that also show high conductive heat flow. Higher spatial variability in the heat flow patterns compared to the magnetization is consistent with the heat flow reflecting the currently active but ephemeral thermal environment of fluid flow, while crustal magnetization is representative of the static time-averaged effect of hydrothermal alteration. A general NW to SE trend in reduced magnetization across the Raven area correlates closely with the distribution of hydrothermal deposits and heat flux patterns and suggests that the fluid circulation system at depth is likely controlled by local crustal structure and magma chamber geometry. Magnetic gradient tensor components computed from vector magnetic data improve the resolution of the magnetic anomaly source and indicate that the hydrothermally altered zone directly beneath the Raven site is approximately 15 {\texttimes} 106 m3 in volume.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1002/2014JB011223},
	author = {Tivey, M A and Johnson, H P and Salmi, M S and Hutnak, M}
}
@article {Salmi2014,
	title = {{Quantitative estimate of heat flow from a mid-ocean ridge axial valley, Raven field, Juan de Fuca Ridge: Observations and inferences}},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {9},
	year = {2014},
	pages = {6841{\textendash}6854},
	abstract = {A systematic heat flow survey using thermal blankets within the Endeavour segment of the Juan de Fuca Ridge axial valley provides quantitative estimates of the magnitude and distribution of conductive heat flow at a mid-ocean ridge, with the goal of testing current models of hydrothermal circulation present within newly formed oceanic crust. Thermal blankets were deployed covering an area of 700 by 450 m in the Raven Hydrothermal vent field area located 400 m north of the Main Endeavour hydrothermal field. A total of 176 successful blanket deployment sites measured heat flow values that ranged from 0 to 31 W m-2. Approximately 53{\%} of the sites recorded values lower than 100 mW m-2, suggesting large areas of seawater recharge and advective extraction of lithospheric heat. High heat flow values were concentrated around relatively small {\textquotedblleft}hot spots.{\textquotedblright} Integration of heat flow values over the Raven survey area gives an estimate of conductive heat output of 0.3 MW, an average of 0.95 W m-2, over the survey area. Fluid circulation cell dimensions and scaling equations allow calculation of a Rayleigh number of approximately 700 in Layer 2A. The close proximity of high and low heat flow areas, coupled with previous estimates of surficial seafloor permeability, argues for the presence of small-scale hydrothermal fluid circulation cells within the high-porosity uppermost crustal layer of the axial seafloor.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1002/2014JB011086},
	author = {Salmi, M S and Johnson, H P and Tivey, M A and Hutnak, M}
}
@article {Hansen2013,
	title = {{Mylonitic deformation at the Kane oceanic core complex: Implications for the rheological behavior of oceanic detachment faults}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {14},
	year = {2013},
	pages = {3085{\textendash}3108},
	abstract = {The depth extent, strength, and composition of oceanic detachment faults remain poorly understood because the grade of deformation-related fabrics varies widely among sampled oceanic core complexes (OCCs). We address this issue by analyzing fault rocks collected from the Kane oceanic core complex at 23{\textdegree}30'N on the Mid-Atlantic Ridge. A portion of the sample suite was collected from a younger fault scarp that cuts the detachment surface and exposes the interior of the most prominent dome. The style of deformation was assessed as a function of proximity to the detachment surface, revealing a \~{}450 m thick zone of high-temperature mylonitization overprinted by a \~{}200 m thick zone of brittle deformation. Geothermometry of deformed gabbros demonstrates that crystal-plastic deformation occurred at temperatures {\textgreater}700{\textdegree}C. Analysis of the morphology of the complex in conjunction with recent thermochronology suggests that deformation initiated at depths of \~{}7 km. Thus we suggest the detachment system extended into or below the brittle-plastic transition (BPT). Microstructural evidence suggests that gabbros and peridotites with high-temperature fabrics were dominantly deforming by dislocation-accommodated processes and diffusion creep. Recrystallized grain size piezometry yields differential stresses consistent with those predicted by dry-plagioclase flow laws. The temperature and stress at the BPT determined from laboratory-derived constitutive models agree well with the lowest temperatures and highest stresses estimated from gabbro mylonites. We suggest that the variation in abundance of mylonites among oceanic core complexes can be explained by variation in the depth of the BPT, which depends to a first order on the thermal structure and water content of newly forming oceanic lithosphere.},
	keywords = {AUV ABE (Autonomous Benthic Explorer), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1002/ggge.20184},
	author = {Hansen, L N and Cheadle, M J and John, B E and Swapp, S M and Dick, H J B and Tucholke, B E and Tivey, M A}
}
@article {Johnson2010,
	title = {{Hydrothermal circulation within the Endeavour Segment, Juan de Fuca Ridge}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {11},
	year = {2010},
	pages = {Q05002},
	abstract = {Areas of the seafloor at mid-ocean ridges where hydrothermal vents discharge are easily recognized by the dramatic biological, physical, and chemical processes that characterize such sites. Locations where seawater flows into the seafloor to recharge hydrothermal cells within the crustal reservoir are by contrast almost invisible but can be indirectly identified by a systematic grid of conductive heat flow measurements. An array of conductive heat flow stations in the Endeavour axial valley of the Juan de Fuca Ridge has identified recharge zones that appear to represent a nested system of fluid circulation paths. At the scale of an axial rift valley, conductive heat flow data indicate a general cross-valley fluid flow, where seawater enters the shallow subsurface crustal reservoir at the eastern wall of the Endeavour axial valley and undergoes a kilometer of horizontal transit beneath the valley floor, finally exiting as warm hydrothermal fluid discharge on the western valley bounding wall. Recharge zones also have been identified as located within an annular ring of very cold seafloor around the large Main Endeavour Hydrothermal Field, with seawater inflow occurring within faults that surround the fluid discharge sites. These conductive heat flow data are consistent with previous models where high-temperature fluid circulation cells beneath large hydrothermal vent fields may be composed of narrow vertical cylinders. Subsurface fluid circulation on the Endeavour Segment occurs at various crustal depths in three distinct modes: (1) general east to west flow across the entire valley floor, (2) in narrow cylinders that penetrate deeply to high-temperature heat sources, and (3) supplying low-temperature diffuse vents where seawater is entrained into the shallow uppermost crust by the adjacent high-temperature cylindrical systems. The systematic array of conductive heat flow measurements over the axial valley floor averaged \~{}150 mW/m2, suggesting that only about 3{\%} of the total energy flux of ocean crustal formation is removed by conductive heat transfer, with the remainder being dissipated to overlying seawater by fluid advection.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2009GC002957},
	url = {http://dx.doi.org/10.1029/2009GC002957},
	author = {Johnson, H P and Tivey, M A and Bjorklund, T A and Salmi, M S}
}
@article {Tivey2002,
	title = {{Crustal magnetization reveals subsurface structure of Juan de Fuca Ridge hydrothermal fields}},
	journal = {Geology},
	volume = {30},
	number = {11},
	year = {2002},
	pages = {979{\textendash}982},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0091-7613},
	doi = {10.1130/0091-7613(2002)030<0979:CMRSSO>2.0.CO;2},
	url = {http://dx.doi.org/10.1130/0091-7613(2002)030{\%}3C0979:CMRSSO{\%}3E2.0.CO 2},
	author = {Tivey, M A and Johnson, H P}
}
