@article {Waters2013,
	title = {{Sill to surface: Linking young off-axis volcanism with subsurface melt at the overlapping spreading center at 9{\textdegree}03'N East Pacific Rise}},
	journal = {Earth and Planetary Science Letters},
	volume = {369{\textendash}370},
	year = {2013},
	pages = {59{\textendash}70},
	abstract = {No young, off-axis, mid-ocean ridge lavas have yet been directly linked to underlying off-axis melt bodies. In this study, we present new measurements of 238U{\textendash}230Th{\textendash}226Ra{\textendash}210Pb isotope compositions for a suite of lavas from the overlapping spreading center (OSC) at 9{\textdegree}03'N on the East Pacific Rise (EPR). These lavas span a large range of compositions, from basalt to dacite, and include both axial and off-axis samples recovered from a prominent, axis-parallel pillow ridge and a flat-topped seamount that overlie the westernmost extent of a 4-km-wide melt lens (Kent et al., 2000). We report 210Pb excesses in axial basalts and basaltic andesites, which we suggest results from gas-magma fractionation of 222Rn from 226Ra beneath dacite magmas. In addition, our U-series ages agree with visual observations, indicating that while most recent volcanic activity occurs at the spreading axis, active volcanism also occurs away from the axis. Specifically, the off-axis pillow ridge and seamount samples overlying the off-axis subsurface melt body have eruption ages of less than 8~ka, and likely as young as 1~ka, despite being located on crust that has a spreading age of {\~{}}75~ka. The young ages of these lavas, combined with existing geological, geochemical and geophysical constraints, provide evidence for a genetic link between the pillow ridge and seamount lavas and the seismically imaged, underlying off-axis melt lens. This link demonstrates that off-axis volcanism does not necessarily come from a sub-axial magma body and can be sourced directly from off-axis magma bodies.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2013.03.006},
	url = {http://www.sciencedirect.com/science/article/pii/S0012821X13001209},
	author = {Waters, C L and Sims, K W W and Klein, E M and White, S M and Reagan, M K and Girard, G}
}
@mastersthesis {Waters2010,
	title = {{Temporal and petrogenetic constraints on volcanic accretionary processes at 9-10 degrees north East Pacific Rise}},
	volume = {Ph.D.},
	year = {2010},
	pages = {258},
	school = {Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution},
	type = {phd},
	address = {Cambridge, MA and Woods Hole, MA},
	abstract = {Volcanic accretion at the fast-spreading East Pacific Rise (EPR) occurs over a {\~{}}2-4 km wide neo-volcanic zone on either side of the axial summit trough (AST). Eruption ages are critical for understanding the distribution and timing of volcanic and magmatic activity. Uranium series nuclides are susceptible to fractionation by magmatic processes that occur beneath mid-ocean ridges, and the half-lives of 226Ra (1.6 kyrs) and 230Th (75 kyrs) make them ideally suited for determining eruption ages and placing constraints on eruption frequency and temporal changes in magma chemistry. Accordingly, major and trace element, and long-lived radiogenic and 238U-230Th-226Ra isotope compositions were measured in basalts from 9{\textordmasculine}-10{\textordmasculine}N EPR to determine eruption ages and to place temporal constraints on volcanic and magmatic processes. At 9{\textordmasculine}30{\textquoteright}N EPR, 238U-230Th-226Ra compositions indicate that trace elementally and isotopically enriched mid-ocean ridge basalt (MORB) collected off-axis erupted {\textgreater}8 ka and that E-MORB magmatism is interspersed with normal, depleted MORB magmatism. Lava ages are consistent with eruption from the AST and flow down the ridge flanks, which is in contrast to previous studies that suggested E-MORB erupted from off-axis vents. At 9{\textordmasculine}50{\textquoteright}N EPR, discrete eruptive units are distinguished by high precision 238U, 232Th, and 226Ra sample concentrations, but because the resolution of the 230Th-226Ra model age dating technique is {\~{}}{\textpm}1 kyrs, the surprisingly young ages of these lavas prohibit the construction of an explicit, time-constrained lava stratigraphy. Nonetheless, seven different flows identified within 0.8-2.0 km west of the AST imply greater frequency of flows to these distances than previously recognized. Model age dating of ferrobasalts, basaltic andesites, andesites, and dacites sampled from the east limb of the overlapping spreading center at 9{\textordmasculine}03{\textquoteright}N EPR is difficult due to uncertainties in magma residence times. However, (226Ra/230Th) disequilibria indicate recent basaltic volcanism ({\textless}{\textless}8 ka) up to {\~{}}4 km off-axis. The axial graben at the rise crest sources the most recent volcanic activity and is the dominant location for eruption of high-silica magmas. Major element, trace element, 87Sr/86Sr, and (234U/238U) isotope compositions are consistent with the formation of dacite magmas by extensive crystallization, and 238U-230Th-226Ra systematics imply crustal residence times of {\~{}}8 kyrs.},
	keywords = {AUV ABE (Autonomous Benthic Explorer), HOV Alvin (Human Occupied Vehicle), ROV DSL-120 (Remotely Operated Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1575/1912/3750},
	url = {http://hdl.handle.net/1912/3750},
	author = {Waters, C L}
}
