Largely allochthonous Triassic units in the Central Betics inferred from their contrasting paleogeographic origin (Cambil, Jaén, Spain)

Abstract

Triassic clayey-evaporitic materials played an important role in the detachment of tectonic units when structuring the Betic Cordillera. In the Cambil sector (Jaén, southern Spain), Triassic outcrops of detrital-evaporitic materials and carbonates have been interpreted as a nappe ("Cambil nappe"). The great development of breccias with clayey-gypsiferous matrix within these materials may be related to an olistostromic unit of the Oligocene-Aquitanian. However, such a redeposit of Triassic materials in the Subbetic Zone during the Miocene is controversial. The geological mapping carried out in this study reveals the tectonic complexity of the area. Large blocks of different nature and age crop out throughout the sector. The identification of Muschelkalk carbonate units of diverse paleogeographic origin, based on the Triassic stratigraphy, implies structures undergoing displacements of almost one hundred kilometers. Largely brecciated bands would be related, in this context, to tectonic structures of brittle-plastic range developed on clayey-gypsiferous materials. Salt tectonics alone cannot explain these regional displacements; hence most of the described tectonic fabrics must be associated with the thrusting and strikeslip faulting of the Betic fold and thrust belt.