Integration of palaeomagnetic data, basement-cover relationships and theoretical calculations to characterize the obliquity of the Altomira–Loranca structures (central Spain)

The main objective of this work is to characterize the structures belonging to the Altomira Range and Loranca Basin (SW Iberian Chain, Central Spain) in terms of understanding their present-day orientation, highly oblique with respect to the NW-SE orientation of adjacent structures of the Iberian Chain. The Altomira and Loranca fold and thrust belts present a slightly curved geometry with a general north-south orientation at their central sector, and structures oriented NNE-SSW and north-south to NNW-SSE at their northern and southern sectors, respectively. Palaeomagnetic data from Middle Eocene-Lower Miocene rocks (including clays, fine sandstones and limestones) reveal the absence of vertical-axis rotations in the central sector of the studied area, where structures are oriented north-south, and up to 17° of clockwise and 21° of anticlockwise vertical-axis rotations in the northern and southern sectors, respectively. These data are supported by calculations of the theoretical vertical-axis rotations from shortening estimates and basement-cover structural relationships. This approach highlights the importance of integrating different datasets to characterize the obliquity of fold and thrust belts. © 2016 The Author(s).
This work was funded by the project KINESAL (CGL2010-21968-C02-02) of the Spanish Ministry of Economy and Competitiveness and a PhD-IGME grant for the first author. It is a contribution of the Geomodels Research Institute and the Grup de Recerca de Geodinámica i Análisi de Conques (2014SGR467, supported by the Agència de Gestió d’Ajuts Universitaris i de Recerca and the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya).