Conference:
12th Congress RCMNS, 6-11 September, Vienna, Austria.
Author:
Jean-Pierre Suc, Georges Clauzon, Speranta-Maria Popescu.
Abstract:
Some classical signatures of the Messinian Salinity Crisis in the Mediterranean Basin (Clauzon, 1999) have been founded in the Dacic Basin (eastern Paratethys) in the area of Turnu Severin, close to the course of the modern Danube, namely: (1) an erosional surface overlain by the clay deposits belonging to calcareous nannofossils Zone NN12; (2) An impressive Gilbert-type fan delta.
In addition to evaporate deposition and the presence of an erosional surface in the Black sea (Letouzy et al., 1978, Hsü & Giovanolli, 1979; Gillet et al., 2004, Gillet, 2004), these new elements located at the outlet of the Iron Gates assert that the Eastern Paratethys was also severely affected by the Messinian Salinity Crisis (Clauzon et al., 2005). Influxes of Mediterranean nannofloras and dinocyst penetrated the Dacic Basin (Marunteanu and Papaianopol, 1998; Drivaliari et al., 1999; Clauzon et al., 2005, Snel et al., in press) and northwestern part of the Euxinian Basin (Semeneko & Olejnik, 1995) during events corresponding to Zones NN11 and NN12, i.e. just before and just after the desiccation of the Mediterranean (Snel et al., in press). Hence, new data on Mediterranean influxes into the eastern Paratethys, and new field evidences from the Dacic Basin, suggest that the Mediterranean Sea and the eastern Paratethys were connected at high sea-level just before and just after the crisis, providing another explanation for Black sea desiccation other the its drainage into the desiccated Mediterranean Basin. Our data suggest that high sea-level cross exchanges existed between the Mediterranean Sea and the eastern Paratethys (Clauzon et al., 2005). The modern course of the Danube River (i.e. after the Carpathians Mountains) appears as an immediate consequence of the salinity crisis, and rapidly reached a course similar to its modern one over the Romanian Plain. The Messinian erosional surface developed along the Danube course and along its main tributaries whereas the northern part of the Dacic Basin remained as a perched lake, fed by Carpathians rivers owing to a regional positive hydrologic budget. This area endured continuous sedimentation, as was proposed for the Po valley and Adriatic realm (Clauzon et al., 1997). Henceforth, the Lago Mare must be considered a triple event. Two events LM1 and LM3, affected only the Mediterranean margins: one Paratethyan water incursion occurred just before the Mediterranean became desiccated, the other marking the Zanclean reflooding of the Mediterranean, they respectively correspond to isotope stages TG11 (5.52 Ma) and TG5 (5.33 Ma) (Clauzon et al., 2005). They are only recoded in the marginal and perched satellite basins. They did not affect the deep Mediterranean Basin Lakes (containing ostracods of the Cyprideis group), which we believe to have developed (LM2 event) when the Mediterranean was desiccated, just before the Zanclean infilling. The gateways followed by these water exchanges are more clearly defined. A proto-Bosporus Strait seems to be unnecessary, but a gateway trough Macedonia and Bulgaria seems possible (Hsü et al., 1977) and is being explored.