Geochemistry, Geophysics, Geosystems

  1. Regular Articles

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    2. Regular Articles
    3. Research Articles
    1. You have full text access to this OnlineOpen article
      Geologic history of the summit of Axial Seamount, Juan de Fuca Ridge (pages 4403–4443)

      David A. Clague, Brian M. Dreyer, Jennifer B. Paduan, Julie F. Martin, William W. Chadwick, David W. Caress, Ryan A. Portner, Thomas P. Guilderson, Mary L. McGann, Hans Thomas, David A. Butterfield and Robert W. Embley

      Version of Record online: 4 OCT 2013 | DOI: 10.1002/ggge.20240

      Key Points

      • All 35 lava flows inside the caldera erupted within the last 800 years
      • More primitive and depleted lavas erupted only from 700-800 years ago
      • The summit caldera formed ~31 kyr ago
    2. You have full text access to this OnlineOpen article
      Petrological variability of recent magmatism at Axial Seamount summit, Juan de Fuca Ridge (pages 4306–4333)

      Brian M. Dreyer, David A. Clague and James B. Gill

      Version of Record online: 3 OCT 2013 | DOI: 10.1002/ggge.20239

      Key Points

      • Multiple basalt types erupted at Axial summit in a time sequence
      • Parental magmas vary subtly, and lava share a uniform differentiation path
      • Recharge varies in space, time, & composition on centennial scales
    3. You have free access to this content
      The 1998 eruption of Axial Seamount: New insights on submarine lava flow emplacement from high-resolution mapping (pages 3939–3968)

      W. W. Chadwick Jr., D. A. Clague, R. W. Embley, M. R. Perfit, D. A. Butterfield, D. W. Caress, J. B. Paduan, J. F. Martin, P. Sasnett, S. G. Merle and A. M. Bobbitt

      Version of Record online: 2 OCT 2013 | DOI: 10.1002/ggge.20202

      Key Points

      • The 1998 eruption at Axial Seamount created four lava flows totaling 31 x 106 m3
      • Nearly the entire area of the flows was mapped with 1-m resolution bathymetry
      • The detailed morphology and other mapping data help interpret their emplacement
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      Numerical modeling of phase separation at Main Endeavour Field, Juan de Fuca Ridge (pages 4021–4034)

      Shreya Singh, Robert P. Lowell and Kayla C. Lewis

      Version of Record online: 2 OCT 2013 | DOI: 10.1002/ggge.20249

      Key Points

      • Modeling MEF to explain temperature and salinity gradients
      • Bottom temperature alone does not explain observed gradients
      • Heterogeneous permeability likely results in observed gradients
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      New packer experiments and borehole logs in upper oceanic crust: Evidence for ridge-parallel consistency in crustal hydrogeological properties (pages 2900–2915)

      Keir Becker, Andrew T. Fisher and Takeshi Tsuji

      Version of Record online: 9 AUG 2013 | DOI: 10.1002/ggge.20201

      Key Points

      • Similar hydrogeological structure is seen in two boreholes ~825 m apart
      • Lateral consistency suggests continuity of upper crustal hydrological structure
      • Highest basement permeabilities occur deeper than uppermost few tens of meters
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      Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar (pages 2369–2382)

      G. Xu, D. R. Jackson, K. G. Bemis and P. A. Rona

      Version of Record online: 29 JUL 2013 | DOI: 10.1002/ggge.20177

      Key Points

      • COVIS is capable of long-term, quantitative monitoring of a hydrothermal plume
      • Plume flow velocity and volume flux show significant temporal variations
      • Tidal flows affect the plume flow velocity via the current-driven entrainment
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      Sulfide geochronology along the Endeavour Segment of the Juan de Fuca Ridge (pages 2084–2099)

      John W. Jamieson, Mark D. Hannington, David A. Clague, Deborah S. Kelley, John R. Delaney, James F. Holden, Margaret K. Tivey and Linda E. Kimpe

      Version of Record online: 8 JUL 2013 | DOI: 10.1002/ggge.20133

      Key Points

      • 226Ra/Ba dating can be used to reconstruct segment scale venting history
      • Hydrothermal venting within the Endeavour axial valley is over 3000 years old
      • 226Ra/Ba bridges an important dating age gap between 200 to 2000 years old
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      Termination of a 6 year ridge-spreading event observed using a seafloor seismic network on the Endeavour Segment, Juan de Fuca Ridge (pages 1375–1398)

      Robert T. Weekly, William S. D. Wilcock, Emilie E. E. Hooft, Douglas R. Toomey, Paul R. McGill and Debra S. Stakes

      Version of Record online: 6 MAY 2013 | DOI: 10.1002/ggge.20105

      Key Points

      • Over 38,000 earthquakes were located along the Endeavour from 2003-2006
      • Two swarms involved intrusions on both limbs of an overlapping spreading center
      • The 2005 swarms represent the termination of a six-year spreading event
  2. Research Articles

    1. Top of page
    2. Regular Articles
    3. Research Articles
    1. You have free access to this content
      Upper crustal seismic structure of the Endeavour segment, Juan de Fuca Ridge from traveltime tomography: Implications for oceanic crustal accretion (pages 1296–1315)

      Robert T. Weekly, William S. D. Wilcock, Douglas R. Toomey, Emilie E. E. Hooft and Eunyoung Kim

      Version of Record online: 25 APR 2014 | DOI: 10.1002/2013GC005159

      Key Points

      • Seismic velocity structure of mid-ocean ridge segment is strongly heterogeneous
      • Slow velocities at segment ends reflect recent history of ridge propagation
      • Off-axis structure attributed to locally thick layer 2A and cooling of layer 2B
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      The influence of porosity and crack morphology on seismic velocity and permeability in the upper oceanic crust (pages 10–27)

      R. L. Carlson

      Version of Record online: 22 JAN 2014 | DOI: 10.1002/2013GC004965

      Key Points

      • Area of asperity contact accounts for variations of velocity in Layer 2A
      • The porosity of Layer 2A does not decrease with age after 0.2 Ma
      • Crack morphology controls both velocity and permeability in Layer 2A
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      Deep sea hydrothermal plumes and their interaction with oscillatory flows

      Guangyu Xu and Daniela Di Iorio

      Version of Record online: 4 SEP 2012 | DOI: 10.1029/2012GC004188

      Key Points

      • Long-term acoustic measurement of hydrothermal plume vertical velocity
      • Entrainment of ambient ocean water is enhanced by horizontal cross flows
      • Vertical rise height of the plume is dependent on the horizontal cross flow
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      Subseafloor nitrogen transformations in diffuse hydrothermal vent fluids of the Juan de Fuca Ridge evidenced by the isotopic composition of nitrate and ammonium

      Annie Bourbonnais, Moritz F. Lehmann, David A. Butterfield and S. Kim Juniper

      Version of Record online: 1 FEB 2012 | DOI: 10.1029/2011GC003863

      Key Points

      • Isotopic composition (N) of ammonium in high- and low-temperature vent fluids
      • Nitrate N and O isotopes and nitrogen consumption in diffuse vent fluids
      • Evidence for microbial nitrate regeneration in diffuse vent fluids
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      Origin of minor and trace element compositional diversity in anorthitic feldspar phenocrysts and melt inclusions from the Juan de Fuca Ridge

      David T. Adams, Roger L. Nielsen, Adam J. R. Kent and Frank J. Tepley III

      Version of Record online: 22 DEC 2011 | DOI: 10.1029/2011GC003778

      Key Points

      • Melt inclusions trap some of the geochemical signal of their parent magma
      • Different levels of diffusive re-equilibration are evident in plagioclase
      • Geochemical patterns observed in plagioclase phenocrysts vary between samples