The Westernmost Mediterranean evolution: A review of the Alboran and Algero-Balearic basins stratigraphy

The Alboran Basin is the westernmost of the Mediterranean basins. It is composed of different sub-basins and connects toward the east with the Algero-Balearic Basin. Regional studies of these basins are mainly from the ´90s, but the restricted seismic coverage and generally low quality (old acquisition and processing methods) of the seismic profiles were not enough to perform a detailed analysis of the entire sediment infill. More recent works characterize in detail a particular area, but the correlation between the different sub-basins remained beyond the scope of those works. Furthermore, these recent works are usually focused only on the Messinian and younger stratigraphy. Thus, the correlation of the sediment history across the entire region and its integration with the regional tectonic evolution has not been achieved. This results in a bunch of models, different for each sub-basin and not always coherent among them, which makes difficult the understanding of the geodynamic evolution of the region

Based on ~4500 km of new and reprocessed multichannel seismic profiles, together with well and dredge data, we are able to review the westernmost Mediterranean stratigraphy at a regional scale. We have correlated the sediment units deposited since the beginning of the formation of the different sub-basins, and we present for the first time a coherent stratigraphy and large-scale tectonic evolution of the whole region. The results provide the information to test and refine models of the geodynamic evolution of the westernmost Mediterranean.

The main objectives are: (i) To define a seismostratigraphy framework for the entire region, integrating previous interpretations and correlating the sedimentary units among depocentres; (ii) To propose an evolutionary model for each sub-basin; and (iii) To integrate all sub-basins results in an updated general kinematic model for the westernmost Mediterranean region.

Main results shed light on the particular evolution of each sub-basin as well as in the entire basin evolution. The Late Oligocene - Miocene represents the formation stage of the basins, controlled by the evolution of the Gibraltar subduction system. During this period, each sub-basin shows different sedimentary units, supporting differences in their evolution. The Plio-Quaternary corresponds to the deformation stage, driven by the Eurasian-African plates convergence. The Plio-Quaternary sediments are covering the entire area, instead of being restricted to the sub-basins. This latter period is characterized by contractional and strike-slip deformation, accommodated mainly by re-activation of pre-existing crustal structures.