Multiple compression directions and basinal response in a rhomb-shaped terrestrial basin: The Cuevas de Cañart syncline (Iberian Chain, eastern Spain)

Abstract

Rhomb-shaped basins have been commonly attributed to strike-slip tectonics, linked to fault bends and jogs (pull-apart basins). The case-study presented in this work (Las Cuevas de Cañart basin, Iberian Chain) is a 2 km × 5 km continental basin that shows a particular combination of geometric and sedimentary features. It shows a syncline geometry with steeply-dipping limbs, thickness of syn-tectonic sedimentary continental filling of about 1000 m, high amplitude/wavelength ratio, and different fold trends, some of them oblique to the main trend of the Iberian Chain. All these features make it an interesting case of a mixed-type basin, sharing both compressional and strike-slip features. The Cuevas de Cañart basin shows a Mesozoic, pre-compressional sequence linked to the extensional processes dominating in the marginal zones of the Maestrazgo basin, with a series up to 1500 m thick of limestones, sandstones and shales. These units overlie a detachment level (Upper Triassic Keuper facies) and show thickness variations controlled by NW-SE and NE-SW striking normal faults. During the Cenozoic compression, both fault systems were re-activated, and newly formed E-W folds (perpendicular to one of the dominant shortening directions) also appeared in the southern basin margin. The detailed structural study of this basin evidences the role of different types of structures (basement faults, thrusts formed under different compression directions) and the relevance of the detachment level in the evolution of compressional basins and thin-skinned fold-and-thrust belts.