MSC Markers and Recent Deformation : the SIMBAD Cruise on the Balearic Promontory

Agnès Maillard, Olivier Driussi, Anne Briais, Johanna Lofi, Virginie Gaullier, Margarita Garcia, Raphael Bourillot, Christian Huebscher, Lies Loncke, Françoise Sage, and Frank Chanier

The Balearic Promontory is a NE-SW-trending continental high of the Western Mediterranean domain, forming the northeastern extremity of the Betic cordillera. It is bracketed by two extensional basins: the Valencia aborted rift to the north and the Algerian oceanic basin to the south. This peculiar tectonic setting results from coeval extensional and compressionnal deformation which occurred mainly started during Oligo-Miocene times.

The SIMBAD cruise is dedicated to the acquisition of high-resolution seismic-reflection data to study the sedimentary deposits linked to the Messinian Salinity Crisis (MSC) in the aim (1) to follow their continuity from shallow to deep areas, (2) to quantify the post-Messinian tectonic reactivation of the Balearic Promontory.

Indeed, the MSC markers are ubiquitous in the area and lying at a different depth: onshore where drillings show evaporite in the Palma basin and offshore in the deep Algerian basin. Between those extreme, thin evaporites are observed. The continuous record of the MSC evaporites permits to understand the lateral relationship between the onland marginal evaporites and the deep basin evaporites, which is a subject of large controversy. This point is however essential to resolve as it is a key to constrain the scenario of the Messinian Salinity Crisis.

Moreover, these markers record lateral and vertical deformation from the Messinian to the Present. Evidence for recent compression is expressed (i) by small folds and thrusts, which are well expressed in the bathymetry and mainly appear as detached structures reworking former tilted blocks and/or Betic thrusts, (ii) by large-scale flexures that seem to be deeply rooted, (iii) or by a regional tilting toward the Algerian basin, showing 1km vertical shift of the Top MSC surface. These observations question the transfer of the Africa-Eurasia convergence from the Algerian inverted margin to the Balearic Promontory through the oceanic crust of the Algerian basin.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013