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EarthTalk by Damien do Couto

Streaming from KU

19.02.2019 | Susanne Weis Fogh

Dato fre 22 feb
Tid 12:00 13:30
Sted Aud 1671-137

Abstract:

Late Cenozoic tectono-stratigraphic evolution of the Alboran domain: insights on the geodynamic history and the Messinian Salinity Crisis

During the Neogene, the geodynamics of the Mediterranean Sea was marked by the development of backarc basins initiated after a major change in the subduction regime, during the Oligocene. The Alboran Sea, located at the western end of the Mediterranean Sea, has been affected by complex tectonic settings during its history. Based on a multidisciplinary "land-sea" approach, this work focuses on two major research topics: it aims (1) to better understand the opening and deformation processes of key sedimentary basins during the Neogene, and (2) to study the effects and imprints of the Messinian Salinity Crisis onto the basins.

Tectonic and stratigraphic analysis of the thickest sedimentary accumulation called Western Alboran Basin (WAB), located above the hinge of the E-dipping Tethyan slab, led to build an original tectonic scenario from the Early to Middle Miocene. The inception of extension was triggered by major crustal shear zones favoring the exhumation of the metamorphic basement. By comparison with the tectonic regime affecting the metamorphic basement in the meantime, geometry of the sedimentary sequences shows that the subsidence is most probably controlled by the slab-pull effect of the underlying oceanic slab. In the Betic Cordilleras, a second generation of sedimentary basins, as the Sorbas Basin, developed along metamorphic core complexes exhumed during an extension regime which abruptly passed into a compressive deformation.

Stratigraphic analyses, supported by micropaleontological investigations and 3D modeling, evidenced that peripheral basins bounding the Alboran Sea, in particular the Sorbas Basin, have been affected by a significant subaerial erosional phase in response to the Messinian Salinity Crisis. The extensive stratigraphic analysis of seven hundreds of seismic profiles demonstrated the onshore/offshore continuity of fluvial canyon morphologies recognized on land. The revealed river network pattern beneath the Alboran Sea reinforces the idea of a total emersion of the Alboran domain for ~160,000 years during the Messinian. A new scenario is then proposed to explain the reopening of the worldwide oceanic connection with the Mediterranean realm.

Institut for Geoscience, Forelæsning / foredrag