Upwarp of anomalous asthenosphere beneath the Rio Grande rift

摘要: Continental rifts are possible analogues of mid-ocean ridges, although major plate tectonic features less clearly observed1. Current thermal models ridges2–4 consist solid lithospheric plates overlying the hotter, viscous asthenosphere, with thickness increasing away from ridge axis. The lower boundary lies at or near melting point isotherm, so that greater depths higher temperatures account for viscosity, seismic velocities and possibly partial melting. Upwarp this axis concentrates heat there, thus lowering densities by expansion raising sea floor to level isostatic equilibrium. At slow spreading a central graben forms owing mechanics magma injection into crust5. Topography, flow, gravity studies support these models. On continents, low-velocity channel has been observed, it is poorly developed beneath ancient cratons6–9. Plate have applied continental basins margins10–12, but further similarities oceanic remain elusive. Topographic uplift often ascribed Airy type compensation caused crustal thickening, rather than in asthenosphere. Here we discuss Rio Grande rift, southwestern United States. Teleseismic P-wave residuals show regional explained asthenosphere thickening.