Lithospheric velocity model of Texas and implications for the Ouachita orogeny and the opening of the Gulf of Mexico

Abstract

A 3-D shear wave velocity model of Texas has been developed from Rayleigh wave phase velocities by using ambient noise data recorded at the USArray stations. In the upper crust, the Ouachita front separates high velocity in the Laurentia to its west from low velocity in the east and south Texas basins. The Ouachita belt is characterized as a high-velocity zone with local maximums coinciding with known uplifts, which we interpret as accreted island arcs during the Ouachita orogeny. Our model evidences a strong Ouachita lithosphere that helped to buffer crust thinning from the Mesozoic rifting. A significantly low-velocity anomaly is present in southeast Texas in the lower crust and upper mantle. We associate this anomaly with a past asthenosphere upwelling that likely originated from the edge of the subducted slab during the Ouachita collision and was potentially responsible for the opening of the Gulf of Mexico.