1411 / 2024-09-26 22:28:48

What does the Messinian Salinity Crisis teach us about Mediterranean paleo-environmental upheavals?

Messinian Salinity Crisis,paleoenvironmental change.,tectonics,geophysics

Session 53 - Geological analogues for future warm ocean and climate

Between 5.96 Ma and 5.33 Ma, the brutal Messinian Salinity Crisis profoundly disrupted the environment of the Mediterranean basin and surrounding continental masses. This extraordinary crisis, one of the most spectacular that the Earth has known, is linked to the progressive closure of communications with the Atlantic Ocean at the Betic corridor then the Rif corridor. It had a considerable impact on sedimentation and therefore on paleo-environments: the margins brought to the outcrop by the fall in sea level of around 1500 meters were subjected to intense erosion and were cut by deep canyons, while the products of this erosion accumulated at the foot of the slope, in the form of detrital cones. During this period, very short on the geological time scale, a thick evaporitic series was deposited in the deep basins, with a mobile salt layer, subsequently creating intense gravity-driven tectonics all around the Mediterranean. The reflooding in the basal Pliocene (Zanclean) was dazzling following the sudden reestablishment of connections with the Atlantic Ocean at the Strait of Gibraltar. We present here a synthesis of studies on several Mediterranean margins. This integrated approach thus makes it possible to study the impact of the Messinian event on the margins and basins in varied tectono-sedimentary contexts, to overcome certain local control factors specific to each study area (type of margin, thickness/lithology of the eroded series, paleo-morphologies, size of the watershed, tectonic context) and to specify the modalities of the crisis (erosion and deposition processes, volumes involved, modalities of variation of the water body, role of Mediterranean thresholds, climatic variations). The geological recording of this major crisis in the history of the Mediterranean, thanks to the discrimination of proxies, thus offers keys to better understand the major environmental and oceanological changes that resulted from it.