Evaluation of The Crust Boundaries and The Interface Crust-Mantle in The Gulf of Mexico by Potential Field Modeling.

Large regional geologic studies are significantly influenced by deep geologic conditions of tectonic character. Those conditions are generally associated to mantle- uplift or collapse and it's relevant to understand such effects on deep Gulf of Mexico studies, where several disciplines participate. In this work one main goal is to determine a mantle model useful to obtain the isostatic corrections for the Bouguer gravity anomaly data. In a first stage we calculated a map of the mantle- top- depth distribution (similar to crust- base location). We evaluated these map in order to infer some tectonic implications for the Gulf of Mexico. We used the Airy's isostatic model as initial input. Calculation of the crust-mantle interface from the satellite free air anomaly was performed by modeling of 30 gravity profiles with a separation of around 40 km. Four layers were considered: the water- and the sedimentary- column with average densities of 2,55 and 1,03 g/cm3, respectively; the basement constituted by several blocks with laterally varying densities as observed on the gravity anomaly, whose top was constrained from previous magnetic modeling; a density average of 3,27 g/cm3 was assigned to the mantle layer. We used the crust-mantle interface derived from the Airy's as initial point for the 2D gravity modeling. The top of the mantle was moved, as well as the densities considered for the basement blocks, until the global misfit for all the modeled sections was minimized. The top of the mantle was estimated and it was depicted in a contour map. Gravity modeling together with previous results from the aeromagnetic data processing allowed us to infer the main crust boundaries for the Gulf of Mexico (Continental, Transitional and Oceanic).