Upper Mantle Structure of the Southern US Continental Margin From Teleseismic Traveltime Tomography

摘要

The southern U.S. continental margin records a rich tectonic history spanning similar to 1.35 Ga, including two complete Wilson cycles. Due to a thick sediment cover, the paucity of local seismicity, and sparse seismic instrumentation, the tectonomagmatic evolution of this passive margin remains uncertain. The recent USArray seismic network offers an opportunity to address unresolved issues by imaging the crust and upper mantle. Direct teleseismic P and S traveltimes recorded at similar to 1,600 stations are mapped into 3-D velocity perturbations. P and S tomography models, although generated independently, are broadly consistent, with a strong correlation between anomaly patterns in the sublithospheric mantle and known crustal features. Fast mantle velocities correspond to the Laurentia Craton and Llano and Grenville terranes, while intracratonic rift systems and Paleozoic arc terranes are marked by slow anomalies in the upper mantle.