Three‐dimensional seismic velocity structure of the northwestern United States

We present a high‐resolution, three dimensional, P‐wave tomography model for the northwestern United States. Major features of the model include clear, well‐resolved images of the Juan de Fuca–Gorda slab to depths of at least 500 km, reduced velocities beneath Newberry volcano and north‐central Oregon, increased velocities beneath the Idaho batholith, and a deep, slab‐like, eastward‐dipping feature of increased velocities beneath Nevada. We find no evidence for a mantle plume in this region, and demonstrate that suggested disruption of the Juan de Fuca slab beneath Oregon in the vicinity of Newberry volcano is an inversion artifact. We interpret the primary features of this new model within the framework of post‐Laramide tectonomagmatism and the continuing tectonic evolution of the Cascadia Subduction Zone. A model explaining the regional tectonomagmatic history consistent with the imaged seismic velocity structure is one driven by mantle flow responding to the evolving subduction system.

[1]  J. A. Snoke,et al.  S-wave velocity structure beneath the High Lava Plains, Oregon, from Rayleigh-wave dispersion inversion , 2008 .

[2]  Gary L. Pavlis,et al.  Upper Mantle Heterogeneity beneath North America from Travel Time Tomography with Global and USArray Transportable Array Data , 2008 .

[3]  R. Allen,et al.  The Fate of the Juan de Fuca Plate , 2007 .

[4]  J. Roering,et al.  A lithospheric instability origin for Columbia River flood basalts and Wallowa Mountains uplift in northeast Oregon , 2005, Nature.

[5]  R. Duncan,et al.  Geochronology of age-progressive volcanism of the Oregon High Lava Plains : implications for the plume interpretation of Yellowstone , 2004 .

[6]  Victor E. Camp,et al.  Mantle dynamics and genesis of mafic magmatism in the intermontane Pacific Northwest , 2004 .

[7]  E. Humphreys,et al.  P and S wave velocity and VP/VS in the wake of the Yellowstone hot spot , 2004 .

[8]  S. Lee.  High-resolution estimates of lithospheric thickness from Missouri to Massachusetts, USA , 2002 .

[9]  Richard G. Gordon,et al.  Young tracks of hotspots and current plate velocities , 2002 .

[10]  W. Dickinson.  The Basin and Range Province as a Composite Extensional Domain , 2002 .

[11]  Matthew J. Fouch,et al.  Tectospheric structure beneath southern Africa , 2001 .

[12]  S. Solomon.  Department of terrestrial magnetism , 2000 .

[13]  Kenneth G. Dueker,et al.  Beneath Yellowstone: Evaluating Plume and Nonplume Models Using Teleseismic Images of the Upper Mantle , 2000 .

[14]  J. Nábělek,et al.  Deconvolution of teleseismic body waves for enhancing structure beneath a seismometer array , 1999, Bulletin of the Seismological Society of America.

[15]  Walter H. F. Smith,et al.  New, improved version of generic mapping tools released , 1998 .

[16]  J. Stock,et al.  Pacific-North America Plate Tectonics of the Neogene Southwestern United States: An Update , 1998 .

[17]  Kenneth L. Pierce,et al.  Chapter 1: The track of the Yellowstone hot spot: Volcanism, faulting, and uplift , 1992 .

[18]  J. VanDecar.  Upper-mantle structure of the Cascadia subduction zone from non-linear teleseismic travel-time inversion , 1991 .

[19]  J. Severinghaus,et al.  Chapter 1: Cenozoic geometry and thermal state of the subducting slabs beneath western North America , 1990 .

[20]  Kenneth L. Pierce,et al.  The track of the Yellowstone hot spot--volcanism, faulting and uplift , 1990 .

[21]  Richard W. Carlson,et al.  Crustal genesis on the Oregon Plateau , 1987 .

[22]  C. Weaver,et al.  Upper mantle structure from teleseismic P wave arrivals in Washington and northern Oregon , 1986 .

[23]  R. Armstrong,et al.  Rb-Sr and K-Ar geochronometry of Mesozoic granitic rocks and their Sr isotopic composition, Oregon, Washington, and Idaho , 1977 .

[24]  P. Lipman,et al.  A Discussion on volcanism and the structure of the Earth - Cenozoic volcanism and plate-tectonic evolution of the Western United States. I. Early and middle cenozoic , 1972, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[25]  P. Lipman,et al.  A Discussion on volcanism and the structure of the Earth - Cenozoic volcanism and plate-tectonic evolution of the Western United States. II. Late cenozoic , 1972, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[26]  T. Atwater.  Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America , 1970 .