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[1] The Colorado Plateau is a physiographic province in the western US with an average elevation of $1.9 km where, in contrast to neighboring provinces, there is little evidence of large scale tectonic deformation or magmatism. Recent availability of Earthscope/ USArray seismic data allow us to better examine the crust and upper mantle structure beneath the region and test proposed explanations for the plateau's uplift and relative stability. Using phase velocities for fundamental mode Rayleigh waves and P receiver functions, we perform over 800 joint inversions for 1-D shear wave velocity V S profiles sampling the plateau and surrounding regions down to 150 km depth. We image a sharp change in crustal thickness at the western edge of the Colorado Plateau with a more gradual increase eastward moving into the Rocky Mountains. A relatively thick (≳100 km) lithosphere beneath the plateau extends into the Rocky Mountains to the north. We use empirical scaling relations to estimate densities from our V S results, and predict the associated gravity anomalies, which are inconsistent with the observed distribution of the Bouguer gravity anomalies. We somewhat reconcile the prediction and observations by assuming that lateral density variations below 50 km can be ignored and the lithospheric root is therefore neutrally buoyant. While there is some evidence for small scale convection and lithospheric removal at its edges, the shape of the lithospheric mantle anomaly is consistent with a large scale uplift of the plateau by heating since removal of the Farallon slab. We conclude that the lithospheric root is key to the long term stability of the Colorado Plateau, leading to a colder, stronger crust.Citation: Bailey, I. W., M. S. Miller, K. Liu, and A. Levander (2012), V S and density structure beneath the Colorado Plateau constrained by gravity anomalies and joint inversions of receiver function and phase velocity data,

International audienceMafic volcanism gradually encroaching on the tectonically stable Colorado Plateau in the southwestern United States appears to originate from within Paleoproterozoic lithosphere. New Hf and Nd isotope data strengthen evidence for magma source heterogeneity; other geochemical signatures show these sources to consist dominantly of peridotite. Tomographic and receiver function analyses reveal that young volcanism occurs above or outboard of a pronounced shallowing in the lithosphere-asthenosphere boundary. Melt extraction extends to the base of lithosphere thinned to <75 km, with more shallowly derived melts characterized by higher degrees of partial melting. Accordingly, decompression melting of a reactivated chemical boundary layer +/- asthenosphere, rather than in situ lithospheric melting or melting of lithospheric mantle drips/delaminations, appears to be responsible for recent Colorado Plateau magma generatio

The first example of selective oxidation of sulfides to sulfones and sulfoxides using molecular oxygen under clean conditions was established. The desired products could be easily collected through recrystallization in large-scale preparation.