Middle Jurassic to Cretaceous extensional tectonics and sedimentation in the eastern external zone of the Betic Cordillera

Abstract

Abstract In the External Zones of the eastern Betic Cordillera, two sets of Mesozoic highangle normal faults can be observed, one with ENE-WSW strikes and the other with N-S strikes. Both sets of faults generate half-grabens and grabens, infilled with wedge-shaped and lens-shaped formations deposited during the Late Jurassic to Early Cretaceous. The relationships of these formations indicate progressive tilting of the hanging walls during deposition of the rocks. The largest basins are related to the ENE-WSW faults. The rocks of Middle Jurassic age, which predate the faulting stage, are shallow-marine oolitic limestones. The Lower Cretaceous Fardes Formation shows evidence of deposits closer to the carbonate compensation depth (CCD). This evidence indicates that normal faulting was related to very significant thinning of the continental crust. Palaeomagnetic studies in the area demonstrate the existence during the Miocene of clockwise and counterclockwise rotations with vertical axes. Restoring the faults to their original orientation, the present-day ENE-WSW faults and their main basins had original N-S strikes, while the N-S faults originally had WNW-ESE strikes. This extensional stage occurred at the same time as the rifting of Iberia and North America, the opening of the Gulf of Biscay and the aborted rifting of the Iberian chain.