Abstract

Spanish territory offers a remarkable location to study the Messinian salinity crisis (MSC). So much so, that sub-basins and open margins to the Mediterranean Sea and the Atlantic Ocean can be studied from outcrop data, 2D and 3D seismic surveys, and well logs. From the analysed data, it can be determined that the Messinian sediments are involved in three third-order depositional sequences: (1) Late Tortonian–Messinian, with temperate carbonates, coral reefs and sandy turbidities; (2) Messinian, with on- and offshore deposition of shallow-marine evaporate and isotopic freshwater facies; and (3) Messinian–Early Pliocene, comprising deposits of sandy (Atlantic) and gypsum-sandy turbidites (Mediterranean) that filled incised valleys. From seismic images, the best exploration opportunities involve the lowstand systems tracts (LST), the carbonates and different facies under deep-water evaporates. For these, however, the problem is to establish the source rock, by: (a) the presence of Messinian deep-water paper shales; (b) the gas having to be biogenic in the absence of paper shales; and (c) reaching the maturity level in areas with limestone and coral reef prospects. The above possibilities come from our conception of the Messinian crisis, which was caused by two different episodes: climatic change in a restricted, but not desiccated, Mediterranean Sea, following by multiple sea-level falls and the deposition of their correlative LST turbiditic systems.

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