Crustal and lithospheric architecture of the Gulf of Mexico and its continental margins from ambient noise Rayleigh wave tomography

Abstract:

The Gulf of Mexico formed as a result of continental breakup between the North and South American plates in the Late Jurassic. This region, therefore, offers an opportunity to further our understanding of the geological evolution of continental margins as well as the development of oceanic lithosphere. We are developing a 3D shear-wave velocity model for the Gulf of Mexico region using cross-correlations of the ambient noise field and measurements of Rayleigh wave phase velocities. We employ continuous data recorded by 387 stations in seismic networks in the US, Mexico and Cuba. Our goal is to characterize the transition from the continental margin to the oceanic lithosphere underneath the gulf and identify regions of the gulf underlain by oceanic lithosphere as well as to map out variations in asthenospheric structure. In addition, we aim to better understand the tectonic history of the rifted margins surrounding the Gulf of Mexico. Using the shear-velocity model we will determine the crustal and lithospheric thickness of the region to constrain a model for the opening of the gulf basin. This study also allows us to investigate the thermal structure below the extinct spreading system associated with the opening of the ocean basin. Initial results from our phase-velocity maps show the likely limit of the oceanic domain in the central basin. The prominent Houston magnetic anomaly along the Texas and Louisiana coast corresponds to a high-velocity crustal body in our velocity model suggesting syn-rift igneous intrusion as a likely source.