Geochemistry, Geophysics, Geosystems

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      A controlled-source seismic and gravity study of the High Lava Plains (HLP) of Eastern Oregon (pages 5208–5226)

      Catherine Cox, G. Randy Keller and Steven H. Harder

      Version of Record online: 20 DEC 2013 | DOI: 10.1002/2013GC004870

      Key Points

      • Integrated 2D, crustal scale, P-wave velocity and density models were derived
      • HLP crustal structure is similar to B&R but with thick sediments and volcanics
      • HLP region had moderate extension and magmatic modification in the lower crust
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      Lithospheric structure beneath the High Lava Plains, Oregon, imaged by scattered teleseismic waves (pages 4835–4848)

      Chin-Wu Chen, David E. James, Matthew J. Fouch and Lara S. Wagner

      Version of Record online: 15 NOV 2013 | DOI: 10.1002/ggge.20284

      Key Points

      • The present-day HLP mantle lithosphere is thin or absent
      • Velocity discontinuities are related to regional volcanism
      • Subduction-related processes can explain our seismic images
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      Distinctive upper mantle anisotropy beneath the High Lava Plains and Eastern Snake River Plain, Pacific Northwest, USA (pages 4647–4666)

      Lara S. Wagner and Maureen D. Long

      Version of Record online: 21 OCT 2013 | DOI: 10.1002/ggge.20275

      Key Points

      • SKS splitting and Rayleigh wave dispersion constrain upper mantle anisotropy
      • Both the HLP and eastern SRP exhibit distinctive anisotropic signature
      • Partial melt may affect anisotropy beneath the volcanic tracks
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      Bimodal volcanism of the High Lava Plains and Northwestern Basin and Range of Oregon: Distribution and tectonic implications of age-progressive rhyolites (pages 2836–2857)

      Mark T. Ford, Anita L. Grunder and Robert A. Duncan

      Version of Record online: 8 AUG 2013 | DOI: 10.1002/ggge.20175

      Key Points

      • A single rhyolitic age-progressive <12 Ma volcanic trend cuts across Oregon
      • Basin subsidence caused by intraplated basalts limits some rhyolite exposures
      • No mantle plume is needed for age-progressive volcanism in the High Lava Plains
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      Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California (pages 864–879)

      Christy B. Till, Timothy L. Grove, Richard W. Carlson, Julie M. Donnelly-Nolan, Matthew J. Fouch, Lara S. Wagner and William K. Hart

      Version of Record online: 17 APR 2013 | DOI: 10.1002/ggge.20070

      Key Points

      • <10.5 Ma basalts are from 37–60 km depth and 1185–1383°C
      • The Moho and lithosphere-asthenosphere boundary are located very close to one another (5–10 km) in this region
      • Anhydrous mantle melting is driven by subduction-related mantle flow
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      Crust and upper mantle structure beneath the Pacific Northwest from joint inversions of ambient noise and earthquake data

      Lara S. Wagner, Matthew J. Fouch, David E. James and Sara Hanson-Hedgecock

      Version of Record online: 7 DEC 2012 | DOI: 10.1029/2012GC004353

      Key Points

      • Low crustal Vs in Oregon may indicate partial melting is still present
      • High crustal Vs in the Snake River Plain extends into the Basin and Range
      • Low topography, high gravity, and high Vs may indicate lower crustal flow
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      Temporal and crustal effects on differentiation of tholeiite to calcalkaline and ferro-trachytic suites, High Lava Plains, Oregon, USA

      Martin J. Streck and Anita L. Grunder

      Version of Record online: 6 NOV 2012 | DOI: 10.1029/2012GC004237

      Key Points

      • Crustal processes mainly control variations of tholeiitic lavas
      • Strongly calcalkaline trend is due to AFC processes in a non-subduction setting
      • Extreme differentiation of tholeiite leads to highly enriched trachyandesite
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      Mantle dynamics beneath the Pacific Northwest and the generation of voluminous back-arc volcanism

      Maureen D. Long, Christy B. Till, Kelsey A. Druken, Richard W. Carlson, Lara S. Wagner, Matthew J. Fouch, David E. James, Timothy L. Grove, Nicholas Schmerr and Chris Kincaid

      Version of Record online: 21 AUG 2012 | DOI: 10.1029/2012GC004189

      Key Points

      • We propose a conceptual model for mantle dynamics beneath the Pacific Northwest
      • The main drivers for mantle processes are rollback subduction and extension
      • Our model is consistent with the volcanic history over the past ~20 Ma