The Impact of the Messinian Salinity Crisis on Exploration in the Eastern Mediterranean; New Insights from Comprehensive Seismic Facies Analysis of the Messinian Evaporite Complex

Allen, Hayley; Fraser, Alastair; Jackson, Chris

The offshore Eastern Mediterranean covers an area of c. 230,000 km2 and is located on the northern margin of the subducting African plate. It is a region of numerous tectonic domains that have resulted in a complex, high-relief crustal structure of sub-basins and highs. Superimposed on this complicated structural framework and Mesozoic-Cenozoic sedimentary fill are the vast evaporite-dominated products of the Messinian Salinity Crisis (MSC) deposited between 5.96-5.33 ma. The salt layer is locally >3 km thick and has a total volume of ~1 million km3 which unquestionably exerts a strong influence over the development of the region's petroleum systems.

Recent discoveries in the pre-Messinian of the Levant and offshore Cyprus areas have heightened industry interest and the USGS have estimated that the area may hold a mean of 1.7 billion barrels of recoverable oil and a mean of 122 trillion cubic feet (tcf) of recoverable gas. Nevertheless, the overwhelming majority of research conducted on the MSC has focused on marginal settings, despite the fact that ~90% of the salt sits out in the deep basin.

Our work aims to progress understanding of the development of the MSC in the deep basin by utilizing regional 2-D seismic surveys and well data to perform comprehensive seismic facies analyses of evaporites from the Levant region into the Nile Deep Sea Fan (NDSF). The seismic facies of the MSC have been mapped at an unprecedented level of detail, revealing numerous depositional sequences with a high degree of variability over short distances; chaotic, transparent and highly deformed seismic facies pass laterally into well-bedded, high-amplitude packages, which can inhibit imaging of the pre-Messinian succession. This has led us to propose new models for the stratigraphic development of the region, and poses new questions regarding the effect of these facies variations on calculated velocities and therefore, depth migration and conversion attempts.

The relative youth of this saline giant makes it an excellent natural laboratory and this paper reveals exciting new insights into the structural and stratigraphic complexity of evaporite-bearing successions. In terms of its youth and timeframe, the MSC is unique, although the processes we document here may be applicable to other salt-bearing sedimentary basins.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013