The Messinian Salinity Crisis in the Mediterranean basin: a reassessment of the data and an integrated scenario

Antonio Caruso, Jean Marie Rouchy

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327 Citazioni (Scopus)


After a long period of controversial debate about the interpretation of the Messinian salinity crisis (MSC), a near consensusexisted since the ODP Leg 42A for a model keeping the major lines of the deep basin-shallow water model initially proposed byHsü et al. (1973). The knowledge of the crisis was improved since the 1995s by the availability of a very accurate astronomicallycalibrated timescale. The debate about its interpretation was then reactivated by several new scenarios that questioned most themajor aspects of the previous classical models. The updated re-examination of the most salient features along with consideration ofthe hydrological requirements for evaporite deposition allow us to assess the viability of the new models. We propose an integratedscenario that revives the key points of the previous model with new statements about the chronology, depositional settings,hydrological mechanisms, consequences and correlations with the global changes. A model implying two main stages of evaporitedeposition that affected successively the whole basin with a slight diachronism matches better the whole dataset. The distribution ofthe evaporites and their depositional timing were constrained by the high degree of paleogeographical differentiation and by thethreshold effects that governed the water exchanges. It is assumed that the central Sicilian basin was a deep basin located in amarginal position with regard to the deepest central basins. The restriction of the Mediterranean was predominantly under a tectoniccontrol, but the complex development of the evaporitic crisis implied the interplay of both glacio-eustatic changes and fluctuationsof the circum-Mediterranean climate.The first evaporitic stage (lower evaporites) that includes the deposition of the thick homogeneous halite unit with K–Mg saltinterbeds in the deepest basins is correlated with the major evaporative drawdown and higher aridity, and occurred during theglacial period recorded in the ocean sediments between 6.3 and 5.6Ma. The deposition of the potash in Sicily is tentatively linkedto the two major glacial peaks TG 20 and TG 22, while the end of this first stage is linked to the peak TG 12. The second stage(upper evaporites) correlates with the interval of warming and global sea level rise recorded in the ocean since 5.6–5.5Ma onwards.During this second stage, freshwater contribution increased and culminated by the latest Messinian dilution, i.e. the Lago-Mareevent, as the result of the worsened tectonically driven closure of the Atlantic gateways combined to an evolution towards wetterclimate conditions at least on the mountainous peripheral areas. In fact, reduced inputs of seawater continued to enter at leastepisodically the basin through the MSC explaining the sporadic presence of marine organisms. These inputs reached their lowestvalue and practically ceased during the latest Messinian dilution, just before the abrupt restoration of stable open marine conditionsat the beginning of the Zanclean.A polyphased erosional surface affected the Mediterranean margins during the MSC with several critical episodes. The majorepisode related to the greatest water level fall, more than 1000m, occurred during the deposition of the lower evaporites, from theonset of the evaporite deposition till the end of the first stage. Erosional processes remained active during the second evaporiticstage especially whenever the basin dried-up and a last important event marked by the karstification of the evaporites developedduring the latest Messinian dilution just before the Early Zanclea
Lingua originaleEnglish
pagine (da-a)35-67
Numero di pagine33
RivistaSedimentary Geology
Volume188 (Special Issue)
Stato di pubblicazionePublished - 2006

All Science Journal Classification (ASJC) codes

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