Controls on syn-kinematic sedimentation in an asymmetrical extensional basin, Sorbas basin SE-Spain

Abstract

Asymmetrical extensional basins are often associated with large-scale footwall exhumation. The sediment supply from this footwall is controlled by tectonics controlling relief (slope) and rejuvenating the source area as well as climate, controlling precipitation and weathering rates. Contemporaneously, tectonics and climate control base-level fluctuations in the hanging-wall. Thus both supply and accommodation-space are expected to be strongly controlled by tectonics and/or climate during active extension. We aim to improve the understanding of how this balance between tectonics and climate affects the distribution of facies in the basin and how it evolves trough time during active extension. The Sorbas basin (SE Spain) is such a basin located in the hangingwall of an extensional detachment with a marked asymmetric architecture. In order to study the link between controls, high resolution sequence stratigraphy and structural analysis is performed on the syn-kinematic Tortonian deep-water sequence in order to capture the cycles of different scales. Large scale (multiple 100s of meters) non-cyclical facies changes were mainly influenced by changes in the source area induced by tectonics and changes in the slope gradient. Smaller scale (20-150m) changes in facies show a tectonic signature in the first part of the basin fill while toward the end of the Tortonian climate likely controlled the sediment supply to the basin. The smallest scale cycles (meter scale) that could be distinguished were observed along syn-depositional faults likely relate to activity on the main fault.