Tectonic inversion of an asymmetric graben: Insights from a combined field and gravity survey in the Sorbas basin

Abstract

The formation of sedimentary basins in the Alboran domain is associated with the exhumation of metamorphic core complexes over a ca. 15 Ma period through a transition from regional late-orogenic extension to compression. An integrated study coupling field analysis and gravity data acquisition was performed in the Sorbas basin in the southeastern Betic Cordillera. Detailed field observations revealed for the first time that extensional tectonics occurred before shortening in this basin. Two extensional events were recorded with NW-SE to N-S and NE-SW kinematics respectively; the first of which being likely responsible for the basin initiation. Tectonic inversion of the basin then occurred around 8 Ma in an overall ca. N-S shortening context. 2D-gravity sections reveal that the basin acted as an active depocenter as the basin floor locally exceeding 2 km-depth is characterized by a marked asymmetric architecture. Based on this integrated study, we explore a new evolutionary scenario which can be used as a basis for interpretations of the Neogene tectonic history of the southeastern Betics.