Application of net tectonic rotations and inclination analysis to a high-resolution palaeomagnetic study in the Betic Cordillera

Abstract

Abstract Our initial structural investigations of the Sierra Endrinal thrust system in the western External Betic Cordillera suggested a differential block rotation associated with ramp and tipline structures in the thrust system. However, we present an analysis of new, high-resolution palaeomagnetic sampling which refutes this hypothesis and reveals a multicomponent remanence, including a syn-deformational component of magnetization. Due to the structural complications of the thrust system, our palaeomagnetic analysis required only the use of inclination data to determine the timing of magnetization, and comparison with expected inclinations to determine the degree of tilting prior to magnetization. In addition, a finite rotation study involving the combination of inclined axis rotations was preferred to simple bedding tilt corrections. This study emphasizes the usefulness of these techniques in structurally-complex regions, where there may be no valid basis for implementing a fold test, or applying the simple correction of untilting about strike. The study also demonstrates that parts of a thrust system may develop trends that are highly oblique to the regional norm without involving substantial differential rotation about a vertical axis.