La gravimetría como herramienta para la cartografía de dominios tectónicos en márgenes continentales hiperextendidos

Abstract

Geometry of hyperextended margins are very heterogeneous, so the definition of tectonic domains made exclusively from 2D seismic sections presents limitations. In this work the different tectonic domains in this type of margins are analysed and compared from the point of view of their gravity signal. Thus, maps of total horizontal gradient and vertical gradient of Bou- guer anomaly have been calculated and compared with other parameters such as the crustal structure and stretching factor (γ ). This analysis has been carried out in a cross-section already published and proposed as a model for the Iberian Western Margin (Perón-Pinvidic et al., 2013; Tugend et al., 2014; Cadenas et al., 2015), and in four lithospheric scale 2+1/2D gra- vimetric models, constrained by wells-data and deep seismic sections. Obtained results show a significative variation in the absolute values of Bouguer anomaly, thinning factor and cortical structure along the margin and, therefore, of the position of the different domains boundaries. However, “necking” zones, and its transition to the hyperextended domain are characteri- zed in all models by high Bouguer anomaly Total Horizontal Gradient values. This fact allows the mapping of the boundaries between different tectonic domains along the margin in all those areas in the absence of deep seismic information in a more objective and realistic way.