Datos paleomagnéticos en materiales sin-diapíricos Aptienses-Albienses (cuenca Vasco-Cantábrica, N Iberia).

Abstract

In order to obtain a kinematic model linking the diapir formation and the geometry of the syn-diapir sediments, a paleomagnetic study has been conducted in selected syn-diapiric sequences of the Basque-Cantabrian Basin. The studied diapirs (Bakio, Bermeo, Guernika and Mungia) developed during the Early Cretaceous in relation to the North Iberian extensional margin which was subsequently reactivated during the Pyrenean contractional deformation (Late Cretaceous-Miocene). They are cored by Triassic red clays and evaporites and they are flanked by synkinematic Albian shelf and slope carbonates and Upper Albian to Cenomanian siliciclastics. The paleomagnetic study has focused on the synkinematic overburden to detect and quantify vertical axis rotations related to the growth of the diapirs. 29 paleomagnetic sites have been analyzed. After obtaining the site mean directions it can be concluded that most of the sites are remagnetized, hindering the kinematics of the diapirs growth to be deduced. The age of this remagnetization is difficult to assess, it could be either an earlier Albian-Maastrichtian remagnetization or a remagnetization linked to the Pyrenean compression.