Deformation of the western Mediterranean Ridge: Importance of Messinian evaporitic formations

• Published in: Tectonophysics Vol. 263; no. 1; pp. 163 - 190
• Main Authors: Chaumillon, E., Mascle, J., Hoffmann, H.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.1996; Elsevier
• Subjects: Environmental Sciences
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/S0040-1951(96)00035-2

Multichannel seismic data were acquired across several areas of the Mediterranean Ridge (M.R.) in the eastern Mediterranean Sea during the MCS Prismed survey (March 1993). The M.R. is a wide, high-standing and elongated swell, emplaced between the southern Aegean and Africa as a consequence of the long-term convergence and the ongoing collision between Europe and Africa. Sedimentary piling and associated deformation have built a thick deformed sediment wedge, the internal geological structures of which remain poorly understood. Processing of two MCS lines (PM 02 and PM 03) across the western branch of the Mediterranean Ridge reveals that Messinian evaporite-bearing formations, which were deposited within the deep Ionian oceanic basin 5 my ago, play an important part in the present structural deformation of the M.R. accretionary wedge. Within the outer M.R., the Messinian “lower evaporites” are believed to act as one of the main decollement levels, while the top of these formations may operate as a disharmonic layer below thin Plio-Quaternary sediments. The present-day M.R. toe appears to be affected by ductile-flow deformation. However, most of the accreted outer wedge is believed to have resulted from the progressive piling up and associated thrusting of Messinian and overlying Plio-Quaternary sediments. Toward the northeast (i.e., toward the central M.R. domain), a major backthrust zone indicates a structural boundary between the outer, wide and convex M.R. and its inner, rather flat, domain, which is inferred to act as a backstop.