The crustal structure on the southern continental margin of the Gulf of Mexico, as inferred by inverse modeling of gravity data

Abstract

In order to infer the crustal structure in the southern continental margin of the Gulf of Mexico, we performed inverse modeling of isostatic residual gravity data, to obtain a three-dimensional model of density contrast in a region that includes the Los Tuxtlas Volcanic Field, the Veracruz basin and partially the Salina del Istmo basin. As a result of the modeling, the calculated gravity anomaly fits well with the observed data. The model suggests that the Los Tuxtlas Volcanic Field evolved on the verge of a dense body, whose roof is 15 km deep and has a thickness of 10 km, it extends towards the north into the Gulf of Mexico, and it is interpreted as oceanic crust. The southern rim of this body possibly represents the location of the Western Main Transformation Fault, related to the opening of the Gulf of Mexico during the Jurassic, although this inference is speculative. On the inferred basement, possibly constituted by Cretaceous carbonates, the model shows a large sedimentary basin that accommodates Cenozoic siliciclastic sediments with a thickness of up to 10 km, has geometric characteristics related to some known tectonic features, such as the Buried Tectonic Front, in addition to a syncline-type structure, with basal surface at 6 km depth, which accommodates the Western Homocline and the eastern edge of the Tlacotalpan Syncline. The model shows deformed strata that thin towards the tectonic front of the Sierra Zongolica, surrounding the Alto de Anegada and the Los Tuxtlas Volcanic Field, as well as some features related to the Coatzacoalcos Reentrant.