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  • East Pacific Rise  (11)
  • Mantle melting  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Structure and topography of the Siqueiros transform fault system: Evidence for the development of intra-transform spreading centers (1989)
    Springer
    Marine geophysical researches 11 (1989), S. 263-299 
    Details
    ISSN: 1573-0581
    Keywords: transform ; Sea MARC II side-looking sonar ; intratransform spreading centers ; East Pacific Rise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Siqueiros transform fault system, which offsets the East Pacific Rise between 8°20′N–8°30′N, has been mapped with the Sea MARC II sonar system and is found to consist of four intra-transform spreading centers and five strike-slip faults. The bathymetric and side-looking sonar data define the total width of the transform domain to be ≈20km. The transform domain includes prominent topographic features that are related to either seafloor spreading processes at the short spreading centers or shearing along the bounding faults. The spreading axes and the seafloor on the flanks of each small spreading center comprise morphological and structural features which suggest that the two western spreading centers are older than the eastern spreading centers. Structural data for the Clipperton, Orozco and Siqueiros transforms, indicate that the relative plate motion geometry of the Pacific-Cocos plate boundary has been stable for the past ≈1.5 Ma. Because the seafloor spreading fabric on the flanks of the western spreading centers is ≈500 000 years old and parallels the present EPR abyssal hill trend (350°) we conclude that a small change in plate motion was not the cause for intra-transform spreading center development in Siqueiros. We suggest that the impetus for the development of intra-transform spreading centers along the Siqueiros transform system was provided by the interaction of small melt anomalies in the mantle (SMAM) with deepseated, throughgoing lithospheric fractures within the shear zone. Initially, eruption sites may have been preferentially located along strike-slip faults and/or along cross-faults that eventually developed into pull-apart basins. Spreading centers C and D in the eastern portion of Siqueiros are in this initial pull-apart stage. Continued intrusion and volcanism along a short ridge within a pull-apart basin may lead to the formation of a stable, small intra-transform spreading center that creates a narrow swath of ridge-parallel structures within the transform domain. The morphology and structure of the axes and flanks of spreading centers A and B in the western and central portion of Siqueiros reflect this type of evolution and suggest that magmatism associated with these intra-transform spreading centers has been active for the past ≈0.5–1.0 Ma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282579
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  • 2
    Electronic Resource
    Electronic Resource
    The East Pacific Rise and its flanks 8–18° N: History of segmentation, propagation and spreading direction based on SeaMARC II and Sea Beam studies (1992)
    Springer
    Marine geophysical researches 14 (1992), S. 299-344 
    Details
    ISSN: 1573-0581
    Keywords: Mid-Ocean Ridge ; East Pacific Rise ; SeaMARC II ; segmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract SeaMARC II and Sea Beam bathymetric data are combined to create a chart of the East Pacific Rise (EPR) from 8°N to 18°N reaching at least 1 Ma onto the rise flanks in most places. Based on these data as well as SeaMARC II side scan sonar mosaics we offer the following observations and conclusions. The EPR is segmented by ridge axis discontinuities such that the average segment lengths in the area are 360 km for first-order segments, 140 km for second-order segments, 52 km for third-order segments, and 13 km for fourth-order segments. All three first-order discontinuities are transform faults. Where the rise axis is a bathymetric high, second-order discontinuities are overlapping spreading centers (OSCs), usually with a distinctive 3:1 overlap to offset ratio. The off-axis discordant zones created by the OSCs are V-shaped in plan view indicating along axis migration at rates of 40–100 mm yr−1. The discordant zones consist of discrete abandoned ridge tips and overlap basins within a broad wake of anomalously deep bathymetry and high crustal magnetization. The discordant zones indicate that OSCs have commenced at different times and have migrated in different directions. This rules out any linkage between OSCs and a hot spot reference frame. The spacing of abandoned ridges indicates a recurrence interval for ridge abandonment of 20,000–200,000 yrs for OSCs with an average interval of approximately 100,000 yrs. Where the rise axis is a bathymetric low, the only second-order discontinuity mapped is a right-stepping jog in the axial rift valley. The discordant zone consists of a V-shaped wake of elongated deeps and interlocking ridges, similar to the wakes of second-order discontinuities on slow-spreading ridges. At the second-order segment level, long segments tend to lengthen at the expense of neighboring shorter segments. This can be understood if segments can be approximated by cracks, because the propagation force at a crack tip is directly proportional to crack length. There has been a counter-clockwise change in the direction of spreading on the EPR between 8 and 18° N during the last 1 Ma. The cumulative change has been 3°–6°, producing opening across the Orozco and Siqueiros transform faults and closing across the Clipperton transform. The instantaneous present-day Cocos-Pacific pole is located at approximately 38.4° N, 109.5° W with an angular rotation rate of 2.10° m.y.−1 This change in spreading direction explains the predominance of right-stepping discontinuities of orders 2–4 along the Siqueiros-Clipperton and Orozco-Rivera segments, but does not explain other aspects of segmentation which are thought to be linked to patterns of melt supply to the ridge axis. There are 23 significant seamount chains in the mapped area and most are created very near the spreading axis. Nearly all of the seamount chains have trends which fall between the absolute and relative plate motion vectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01203621
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  • 3
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    Submarine deep‐water lava flows at the base of the western Galápagos Platform (2018)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 19 (2018): 3945–3961, doi:10.1029/2018GC007632.
    Description: To investigate the initial phases of magmatism at the leading edge of the upwelling mantle plume, we mapped, photographed, and collected samples from two long, deep‐water lava flows located at the western base of the Galápagos Platform using the remotely operated vehicle Hercules. Lavas were recovered from four areas on the seafloor west of Fernandina volcano, including the western flow fronts of two deep‐water flows, heavily sedimented terrain between the two flows, and the eastern, shallower end of one flow. The sediment cover and morphologies are distinct between the western flow fronts and the eastern region based on seafloor imagery, suggesting that the long lava flows are not a single eruptive unit. Major and trace element concentrations reveal both tholeiitic and alkalic compositions and support the interpretation that multiple eruptive units comprise the deep‐water flows. Alkalic lavas have higher [La/Sm]N ratios (2.05–2.12) and total alkali contents (5.18–5.40) compared to tholeiitic lavas, which have [La/Sm]N ratios ranging from 1.64 to 1.68 and total alkali contents ranging from 3.07 to 4.08 wt%. Radiogenic isotope ratios are relatively homogeneous, suggesting a similar mantle source. We use petrologic models to assess three alternative mechanisms for the formation of the alkalic magmas: (1) high‐pressure crystallization of clinopyroxene, (2) mixing of high silica and mafic magmas, and (3) variable extents of melting of the same mantle source. Our modeling indicates that the alkalic samples form from lower extents of melting compared to the tholeiitic lavas and suggests that the deep‐water alkalic lavas are analogous to the initial, preshield building phase observed south of Hawaii and at the base of Loihi Seamount.
    Description: Dalio Explorer Fund; National Science Foundation (NSF) Grant Number: OCE‐1634952
    Description: 2019-04-25
    Keywords: Submarine volcanism ; Galápagos ; Alkalic magmatism ; Mantle plume ; Mantle melting ; Radiogenic isotopes
    Repository Name: Woods Hole Open Access Server
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  • 4
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    Central Anomaly Magnetization High documentation of crustal accretion along the East Pacific Rise (9°55′–9°25′N) (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q04015, doi:10.1029/2007GC001611.
    Description: Near-bottom magnetic data collected along the crest of the East Pacific Rise between 9°55′ and 9°25′N identify the Central Anomaly Magnetization High (CAMH), a geomagnetic anomaly modulated by crustal accretionary processes over timescales of ∼104 years. A significant decrease in CAMH amplitude is observed along-axis from north to south, with the steepest gradient between 9°42′ and 9°36′N. The source of this variation is neither a systematic change in geochemistry nor varying paleointensity at the time of lava eruption. Instead, magnetic moment models show that it can be accounted for by an observed ∼50% decrease in seismic Layer 2A thickness along-axis. Layer 2A is assumed to be the extrusive volcanic layer, and we propose that this composes most of the magnetic source layer along the ridge axis. The 9°37′N overlapping spreading center (OSC) is located at the southern end of the steep CAMH gradient, and the 9°42′–9°36′N ridge segment is interpreted to be a transition zone in crustal accretion processes, with robust magmatism north of 9°42′N and relatively low magmatism at present south of 9°36′N. The 9°37′N OSC is also the only bathymetric discontinuity associated with a shift in the CAMH peak, which deviates ∼0.7 km to the west of the axial summit trough, indicating southward migration of the OSC. CAMH boundaries (defined from the maximum gradients) lie within or overlie the neovolcanic zone (NVZ) boundaries throughout our survey area, implying a systematic relationship between recent volcanic activity and CAMH source. Maximum flow distances and minimum lava dip angles are inferred on the basis of the lateral distance between the NVZ and CAMH boundaries. Lava dip angles average ∼14° toward the ridge axis, which agrees well with previous observations and offers a new method for estimating lava dip angles along fast spreading ridges where volcanic sequences are not exposed.
    Description: The research project was funded by National Science Foundation under grants OCE-9819261 and OCE- 0096468.
    Keywords: East Pacific Rise ; Magnetic anomalies ; Mid-ocean ridges ; Volcanic processes ; Magnetic source layer
    Repository Name: Woods Hole Open Access Server
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  • 5
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    Submeter bathymetric mapping of volcanic and hydrothermal features on the East Pacific Rise crest at 9°50′N (2007)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q01006, doi:10.1029/2006GC001333.
    Description: Recent advances in underwater vehicle navigation and sonar technology now permit detailed mapping of complex seafloor bathymetry found at mid-ocean ridge crests. Imagenex 881 (675 kHz) scanning sonar data collected during low-altitude (~5 m) surveys conducted with DSV Alvin were used to produce submeter resolution bathymetric maps of five hydrothermal vent areas at the East Pacific Rise (EPR) Ridge2000 Integrated Study Site (9°50′N, “bull's-eye”). Data were collected during 29 dives in 2004 and 2005 and were merged through a grid rectification technique to create high-resolution (0.5 m grid) composite maps. These are the first submeter bathymetric maps generated with a scanning sonar mounted on Alvin. The composite maps can be used to quantify the dimensions of meter-scale volcanic and hydrothermal features within the EPR axial summit trough (AST) including hydrothermal vent structures, lava pillars, collapse areas, the trough walls, and primary volcanic fissures. Existing Autonomous Benthic Explorer (ABE) bathymetry data (675 kHz scanning sonar) collected at this site provide the broader geologic context necessary to interpret the meter-scale features resolved in the composite maps. The grid rectification technique we employed can be used to optimize vehicle time by permitting the creation of high-resolution bathymetry maps from data collected during multiple, coordinated, short-duration surveys after primary dive objectives are met. This method can also be used to colocate future near-bottom sonar data sets within the high-resolution composite maps, enabling quantification of bathymetric changes associated with active volcanic, hydrothermal and tectonic processes.
    Description: This work was supported by an NSF Ridge2000 fellowship to V.L.F. and a Woods Hole Oceanographic Institution fellowship supported by the W. Alan Clark Senior Scientist Chair (D.J.F.). Funding was also provided by the Censsis Engineering Research Center of the National Science Foundation under grant EEC-9986821. Support for field and laboratory studies was provided by the National Science Foundation under grants OCE-9819261 (D.J.F. and M.T.), OCE-0096468 (D.J.F. and T.S.), OCE-0328117 (SMC), OCE-0525863 (D.J.F. and S.A.S.), OCE-0112737 ATM-0427220 (L.L.W.), and OCE- 0327261 and OCE-0328117 (T.S.). Additional support was provided by The Edwin Link Foundation (J.C.K.).
    Keywords: High-resolution bathymetry ; Near-bottom sonar ; East Pacific Rise ; Ridge2000
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: 5546372 bytes
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  • 6
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    Interplay between faults and lava flows in construction of the upper oceanic crust : the East Pacific Rise crest 9°25′–9°58′N (2007)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q06005, doi:10.1029/2006GC001399.
    Description: The distribution of faults and fault characteristics along the East Pacific Rise (EPR) crest between 9°25′N and 9°58′N were studied using high-resolution side-scan sonar data and near-bottom bathymetric profiles. The resulting analysis shows important variations in the density of deformational features and tectonic strain estimates at young seafloor relative to older, sediment-covered seafloor of the same spreading age. We estimate that the expression of tectonic deformation and associated strain on “old” seafloor is ~5 times greater than that on “young” seafloor, owing to the frequent fault burial by recent lava flows. Thus the unseen, volcanically overprinted tectonic deformation may contribute from 30% to 100% of the ~300 m of subsidence required to fully build up the extrusive pile (Layer 2A). Many longer lava flows (greater than ~1 km) dam against inward facing fault scarps. This limits their length at distances of 1–2 km, which are coincident with where the extrusive layer acquires its full thickness. More than 2% of plate separation at the EPR is accommodated by brittle deformation, which consists mainly of inward facing faults (~70%). Faulting at the EPR crest occurs within the narrow, ~4 km wide upper crust that behaves as a brittle lid overlying the axial magma chamber. Deformation at greater distances off axis (up to 40 km) is accommodated by flexure of the lithosphere due to thermal subsidence, resulting in ~50% inward facing faults accommodating ~50% of the strain. On the basis of observed burial of faults by lava flows and damming of flows by fault scarps, we find that the development of Layer 2A is strongly controlled by low-relief growth faults that form at the ridge crest and its upper flanks. In turn, those faults have a profound impact on how lava flows are distributed along and across the ridge crest.
    Description: The field and laboratory studies were supported by NSF grants OCE-9819261 (to H.S., M.A.T., and D.J.F.), OCE-0525863 (D.J.F. and S.A.S.), OCE-0138088 (M.P.), WHOI Vetlesen Foundation Funds (J.E., D.J.F., and S.A.S.). Additional support by INSU/CNRS to J.E. is also acknowledged.
    Keywords: Faulting ; Volcanism ; Mid-ocean ridge ; East Pacific Rise ; Tectonic strain
    Repository Name: Woods Hole Open Access Server
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  • 7
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    Formation of submarine lava channel textures : insights from laboratory simulations (2010)
    American Geophysical Union
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    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): B03104, doi:10.1029/2005JB003796.
    Description: Laboratory simulations using polyethylene glycol (PEG) extruded at a constant rate and temperature into a tank with a uniform basal slope and filled with a cold sucrose solution generate channels that are defined by stationary levees and mobile flow interiors. These laboratory channels consistently display the following surface textures in the channel: smooth, folded, lineated, and chaotic. In the simulations, we can observe specific local conditions including flow rate, position within the channel, and time that combine to develop each texture. The textures in PEG flows form due to relative differences in shear forces between the PEG crust and the underlying liquid wax. Minimal shear forces form smooth crust, whereas folded crust forms when the shear is sufficiently high to cause ductile deformation. Brittle deformation of solid PEG creates a chaotic texture, and lineated crust results from shear forces along the channel-levee margin. We observe similar textures in submarine lava channels with sources at or near the Axial Summit Trough of the East Pacific Rise between 9° and 10°N. We mapped the surface textures of nine submarine lava channels using high-resolution digital images collected during camera tows. These textural maps, along with observations of the formation of similar features in analog flows, reveal important information about the mechanisms occurring across the channel during emplacement, including relative flow velocity and shear stress.
    Description: The cruise was funded by a grant to WHOI from the National Science Foundation (NSF) OCE-9819261, with additional funding provided by WHOI thorough the Vetlesen Foundation. The PEG experiments were funded by NSF OCE-0425073 in a grant to Tracy Gregg.
    Keywords: East Pacific Rise ; Polyethylene glycol (PEG) ; Lava channels
    Repository Name: Woods Hole Open Access Server
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  • 8
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    Geochemistry of lavas from the 2005–2006 eruption at the East Pacific Rise, 9°46′N–9°56′N : implications for ridge crest plumbing and decadal changes in magma chamber compositions (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 11 (2010): Q05T09, doi:10.1029/2009GC002977.
    Description: Detailed mapping, sampling, and geochemical analyses of lava flows erupted from an ∼18 km long section of the northern East Pacific Rise (EPR) from 9°46′N to 9°56′N during 2005–2006 provide unique data pertaining to the short-term thermochemical changes in a mid-ocean ridge magmatic system. The 2005–2006 lavas are typical normal mid-oceanic ridge basalt with strongly depleted incompatible trace element patterns with marked negative Sr and Eu/Eu* anomalies and are slightly more evolved than lavas erupted in 1991–1992 at the same location on the EPR. Spatial geochemical differences show that lavas from the northern and southern limits of the 2005–2006 eruption are more evolved than those erupted in the central portion of the fissure system. Similar spatial patterns observed in 1991–1992 lavas suggest geochemical gradients are preserved over decadal time scales. Products of northern axial and off-axis fissure eruptions are consistent with the eruption of cooler, more fractionated lavas that also record a parental melt component not observed in the main suite of 2005–2006 lavas. Radiogenic isotopic ratios for 2005–2006 lavas fall within larger isotopic fields defined for young axial lavas from 9°N to 10°N EPR, including those from the 1991–1992 eruption. Geochemical data from the 2005–2006 eruption are consistent with an invariable mantle source over the spatial extent of the eruption and petrogenetic processes (e.g., fractional crystallization and magma mixing) operating within the crystal mush zone and axial magma chamber (AMC) before and during the 13 year repose period. Geochemical modeling suggests that the 2005–2006 lavas represent differentiated residual liquids from the 1991–1992 eruption that were modified by melts added from deeper within the crust and that the eruption was not initiated by the injection of hotter, more primitive basalt directly into the AMC. Rather, the eruption was driven by AMC pressurization from persistent or episodic addition of more evolved magma from the crystal mush zone into the overlying subridge AMC during the period between the two eruptions. Heat balance calculations of a hydrothermally cooled AMC support this model and show that continual addition of melt from the mush zone was required to maintain a sizable AMC over this time interval.
    Description: This work has been supported by NSF grants OCE‐0525863 and OCE‐0732366 (D. J. Fornari and S. A. Soule), OCE‐0636469 (K. H. Rubin), and OCE‐ 0138088 (M. R. Perfit), as well as postdoctoral fellowship funds from the University of Florida.
    Keywords: Mid-ocean ridge basalt ; East Pacific Rise ; Eruption ; Trace elements ; Radiogenic isotopes ; Fractional crystallization
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Discovery of active off-axis hydrothermal vents at 9° 54’N East Pacific Rise (2022)
    National Academy of Sciences
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    Publication Date: 2022-11-10
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in McDermott, J. M., Parnell-Turner, R., Barreyre, T., Herrera, S., Downing, C. C., Pittoors, N. C., Pehr, K., Vohsen, S. A., Dowd, W. S., Wu, J.-N., Marjanović, M., & Fornari, D. J. Discovery of active off-axis hydrothermal vents at 9° 54’N East Pacific Rise. Proceedings of the National Academy of Sciences of the United States of America, 119(30), (2022): e2205602119, https://doi.org/10.1073/pnas.2205602119.
    Description: Comprehensive knowledge of the distribution of active hydrothermal vent fields along midocean ridges is essential to understanding global chemical and heat fluxes and endemic faunal distributions. However, current knowledge is biased by a historical preference for on-axis surveys. A scarcity of high-resolution bathymetric surveys in off-axis regions limits vent identification, which implies that the number of vents may be underestimated. Here, we present the discovery of an active, high-temperature, off-axis hydrothermal field on a fast-spreading ridge. The vent field is located 750 m east of the East Pacific Rise axis and ∼7 km north of on-axis vents at 9° 50′N, which are situated in a 50- to 100-m-wide trough. This site is currently the largest vent field known on the East Pacific Rise between 9 and 10° N. Its proximity to a normal fault suggests that hydrothermal fluid pathways are tectonically controlled. Geochemical evidence reveals deep fluid circulation to depths only 160 m above the axial magma lens. Relative to on-axis vents at 9° 50′N, these off-axis fluids attain higher temperatures and pressures. This tectonically controlled vent field may therefore exhibit greater stability in fluid composition, in contrast to more dynamic, dike-controlled, on-axis vents. The location of this site indicates that high-temperature convective circulation cells extend to greater distances off axis than previously realized. Thorough high-resolution mapping is necessary to understand the distribution, frequency, and physical controls on active off-axis vent fields so that their contribution to global heat and chemical fluxes and role in metacommunity dynamics can be determined.
    Description: Financial support was provided by the NSF Awards OCE-1949938 (to J.M.M.), OCE-1948936 (to R.P.-T.), and OCE-1949485 (to D.J.F. and T.B.).
    Keywords: Hydrothermal activity ; Midocean ridge ; Ocean chemistry ; Chemosynthetic ecosystem ; East Pacific Rise
    Repository Name: Woods Hole Open Access Server
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  • 10
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    Relative timing of off‐axis volcanism from sediment thickness estimates on the 8°20’N seamount chain, East Pacific Rise (2023)
    American Geophysical Union
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    Publication Date: 2023-02-16
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Fabbrizzi, A., Parnell‐Turner, R., Gregg, P., Fornari, D., Perfit, M., Wanless, V., & Anderson, M. Relative timing of off‐axis volcanism from sediment thickness estimates on the 8°20’N seamount chain, East Pacific Rise. Geochemistry, Geophysics, Geosystems, 23(9), (2022): e2022GC010335, https://doi.org/10.1029/2022gc010335.
    Description: Volcanic seamount chains on the flanks of mid-ocean ridges record variability in magmatic processes associated with mantle melting over several millions of years. However, the relative timing of magmatism on individual seamounts along a chain can be difficult to estimate without in situ sampling and is further hampered by Ar40/Ar39 dating limitations. The 8°20’N seamount chain extends ∼170 km west from the fast-spreading East Pacific Rise (EPR), north of and parallel to the western Siqueiros fracture zone. Here, we use multibeam bathymetric data to investigate relationships between abyssal hill formation and seamount volcanism, transform fault slip, and tectonic rotation. Near-bottom compressed high-intensity radiated pulse, bathymetric, and sidescan sonar data collected with the autonomous underwater vehicle Sentry are used to test the hypothesis that seamount volcanism is age-progressive along the seamount chain. Although sediment on seamount flanks is likely to be reworked by gravitational mass-wasting and current activity, bathymetric relief and Sentry vehicle heading analysis suggest that sedimentary accumulations on seamount summits are likely to be relatively pristine. Sediment thickness on the seamounts' summits does not increase linearly with nominal crustal age, as would be predicted if seamounts were constructed proximal to the EPR axis and then aged as the lithosphere cooled and subsided away from the ridge. The thickest sediments are found at the center of the chain, implying the most ancient volcanism there, rather than on seamounts furthest from the EPR. The nonlinear sediment thickness along the 8°20’N seamounts suggests that volcanism can persist off-axis for several million years.
    Description: This work was supported by National Science Foundation awards OCE-1356610, OCE-1356822, OCE-1357150, OCE-1754419, OCE-1834797, OCE-2001314, and OCE-2001331.
    Keywords: Off-axis seamounts ; East Pacific Rise ; Sediment thickness ; Seafloor morphology ; Autonomous underwater vehicle ; Eruption history
    Repository Name: Woods Hole Open Access Server
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