This study addresses some aspects of the kinematics and structural setting of the Mediterranean Ridge accretionary complex, particularly those aspects related to the occurrence and distribution of Messinian evaporites. The approach is by (1) identifi cation of the geometry of deformation through reprocessing of existing multichannel seismic refl ection data from the Levantine Basin, aimed at the defi nition of the velocity fi eld and depth imaging; (2) physical modeling in the laboratory, aimed at the study of the kinematics of shortening of sedimentary sequences detaching on viscous décollements; and (3) comparison between the results of the two approaches. We conclude that the thick Messinian sequence of the Levantine Basin is composed primarily of salt, so that the entire evaporitic sequence can be expected to behave as a viscous material. It follows that the main detachment of the post-Messinian wedge is located at the base of the Messinian salt layer. A viscous (salt) décollement would produce thrusting trending normal to the shortening direction, but boundary conditions affect structural trends even more than stress and/or movement direction. Both strain partitioning and the formation of major strike-slip faults within the post-Messinian wedge are prevented by the high angle of convergence between the African and Aegean plates as well as by the low intraplate friction. In addition, we show that curved and anastomosing thrust fronts are refl ected in the cobblestone topography of the Mediterranean Ridge. We fi nally postulate that extension may occur in the central Mediterranean Ridge as a result of the geometry of the plate boundaries. This extension is considered as a possible cause of mud volcanism and mud diapirism.

Modeling deformation and salt tectonics in the Eastern Mediterranean Ridge accretionary wedge

CAMERLENGHI A;ROMANELLI M;SORMANI L;
2004

Abstract

This study addresses some aspects of the kinematics and structural setting of the Mediterranean Ridge accretionary complex, particularly those aspects related to the occurrence and distribution of Messinian evaporites. The approach is by (1) identifi cation of the geometry of deformation through reprocessing of existing multichannel seismic refl ection data from the Levantine Basin, aimed at the defi nition of the velocity fi eld and depth imaging; (2) physical modeling in the laboratory, aimed at the study of the kinematics of shortening of sedimentary sequences detaching on viscous décollements; and (3) comparison between the results of the two approaches. We conclude that the thick Messinian sequence of the Levantine Basin is composed primarily of salt, so that the entire evaporitic sequence can be expected to behave as a viscous material. It follows that the main detachment of the post-Messinian wedge is located at the base of the Messinian salt layer. A viscous (salt) décollement would produce thrusting trending normal to the shortening direction, but boundary conditions affect structural trends even more than stress and/or movement direction. Both strain partitioning and the formation of major strike-slip faults within the post-Messinian wedge are prevented by the high angle of convergence between the African and Aegean plates as well as by the low intraplate friction. In addition, we show that curved and anastomosing thrust fronts are refl ected in the cobblestone topography of the Mediterranean Ridge. We fi nally postulate that extension may occur in the central Mediterranean Ridge as a result of the geometry of the plate boundaries. This extension is considered as a possible cause of mud volcanism and mud diapirism.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.14083/3420
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