Mapping of crustal domains of the Western Iberia margin based on potential fields

Abstract

The structure of the hyperextended West Iberian margin is heterogeneous along its entire length, and it has an extra complexity, since its formation involves several rifting episodes and a later partial tectonic inversion. At its northern end, the West Iberian margin is characterized by a broad domain of extended continental crust that stretches around 300 km from the coast out to a domain of exhumed subcontinental mantle beyond the Galicia Bank. Further south, the continental crust only extends some 200 km from the coast or less before transitioning into the domain of exhumed mantle. The structural correlation between these segments of the margin is difficult to determine exclusively from seismic profile interpretation. In this study we have therefore used advanced enhancement tools applied to gravimetric and magnetic data to highlight the key domains and boundaries of the West Iberia passive margin. The gravity and magnetic maps derived have been used to map the key domains and features of the passive margin. Potential field data have been analysed using FFT techniques, including upward continuation and several derivatives, in order to separate different wavelengths and depth sources, as well as physical lateral variations. The results of this domain mapping exercise have been compared with 2½ D modelling along key seismic transects. This comparison provides and independent validation of the approach. A further advantage of the mapping methodology presented here is the possibility of correlating the offshore structure with the onshore. Domains mapped in the passive margin have been thus correlated with onshore crustal domains defined by geological mapping. This allows us to speculate on the physical properties of the crust in the offshore and to understand the role of Hercynian orogenic structure in the configuration of the West Iberian passive margin.

AAPG Datapages/Search and Discovery Article #90325 © 2018 AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin, Lisbon, Portugal, May 2-3, 2018