SEQUENTIAL STRUCTURAL RESTORATIONS OF THE CONJUGATE NE GULF OF MEXICO US-MEXICO MARGIN: IMPLICATIONS FOR MESOZOIC DYNAMIC TOPOGRAPHY

In this contribution we present crustal-scale structural restorations of the NE Gulf of Mexico US-Mexico conjugate margin from Mesozoic salt deposition to present. We construct four large-scale (100s of km) balanced, sequential structural restorations, two from the US and two from Mexico, to investigate geometry of the original salt basin, paleo-bathymetry, and crustal configurations. The restorations are constrained by 2D and 3D seismic data and >1000 wells. In order to quantify vertical movements through time, we incorporate sequential sedimentary decompaction, flexural isostatic backstripping, and thermal isostatic corrections. The lithospheric stretching (Beta) factor is directly measured from seismic data and varies spatially, and lithologic parameters are determined by well penetrations. We observe that the original salt basin in the NE Gulf of Mexico contained 1-2 km thick salt in a basin 175-400 km across with ca. 1 km of bathymetry after salt deposition. Our findings indicate that the salt basin was both wider and deeper towards the central Gulf of Mexico. At the time of salt deposition there was a topographic high in the paleo-basin center, indicative of ongoing tectonism and exhumation leading up to crustal breakup. Mesozoic subsidence and deposition patterns suggest an evolving depocenter controlled by salt tectonics, crustal breakup dynamics, and the pre-salt section. Our subsidence analysis reveals anomalous vertical movements on all analyzed sections ranging from 500-1000 m during Late Jurassic and Early Cretaceous times. We interpret these vertical movements as dynamic topography, potentially reflecting influence of the CAMP hotspot.