A two‐step process for the reflooding of theMediterranean after theMessinianSalinityCrisis

Abstract

The Messinian Salinity Crisis is well known to have resulted from a significant drop of the Mediterranean sea level. Considering both onshore and offshore observations, the subsequent reflooding is generally thought to have been very sudden. We present here offshore seismic evidence from the Gulf of Lions and re‐visited onshore data from Italy and Turkey that lead to a new concept of a two‐step reflooding of the Mediterranean Basin after the Messinian Salinity Crisis. The refilling was first moderate and relatively slow accompanied by transgressive ravinement, and later on very rapid, preserving the subaerial Messinian Erosional Surface. The amplitude of these two successive rises of sea level has been estimated at ≤500 m for the first rise and 600–900 m for the second rise. Evaporites from the central Mediterranean basins appear to have been deposited principally at the beginning of the first step of reflooding. After the second step, which preceeded the Zanclean Global Stratotype Section and Point, successive connections with the Paratethyan Dacic Basin, then the Adriatic foredeep, and finally the Euxinian Basin occurred, as a consequence of the continued global rise in sea level. A complex morphology with sills and sub‐basins led to diachronous events such as the so‐called ‘Lago Mare’.This study helps to distinguish events that were synchronous over the entire Mediterranean realm, such as the two‐step reflooding, from those that were more local and diachronous. In addition, the shoreline that marks the transition between these two steps of reflooding in the Provence Basin provides a remarkable palaeogeographical marker for subsidence studies.

Crustal Strain in the Marmara Pull‐Apart Region Associated With the Propagation Process of the North Anatolian Fault

“…Two successive steps have been identified with a first sea-level drop of approximately 150 m between 5.97 Ma and 5.60 Ma followed by the major sea-level drop of approximately 1500 m between 5.60 Ma and the end of the MSC [Clauzon et al, 1996;Roveri et al, 2014;Bache et al, 2015;Clauzon et al, 2015], proposed to be placed at 5.46 Ma [Bache et al, 2012]. The MSC is also characterized by different effects that occurred during the Pliocene.…”

“…how to reorganize the Gazhanedere, Kirazlı and Alçıtepe formations with respect to this morphology, refers to the occurrence of the species Ceratolithus acutus with or without Triquetrorhabdulus rugosus (NN12a and 12b subzones, respectively), in the absence of Discoaster quinqueramus not recorded in the Dardanelles area. The main outcome of Melinte-Dobrinescu et al [2009] extensive investigation is that the Alçıtepe Formation was deposited just after the fast marine reflooding that ended the MSC at 5.46 Ma in the latest Messinian [Bache et al, 2012].…”

“…The MSC is also characterized by different effects that occurred during the Pliocene. The fast reflooding of the Mediterranean resulted in Gilbert-type fan deltas as sedimentary complexes filling the fluvial valleys cut during the peak of the MSC [Clauzon et al, 1996;Bache et al, 2012]. Typically, these Gilbert-type fan deltas consist of two superimposed sedimentary bodies deposited over the MES (for a complete description, see : Bache et al, 2012: fig.2).…”

“…The fast reflooding of the Mediterranean resulted in Gilbert-type fan deltas as sedimentary complexes filling the fluvial valleys cut during the peak of the MSC [Clauzon et al, 1996;Bache et al, 2012]. Typically, these Gilbert-type fan deltas consist of two superimposed sedimentary bodies deposited over the MES (for a complete description, see : Bache et al, 2012: fig.2). The underlying and mainly distal body builds up in a sub-aquatic environment and is formed by sandy to conglomeratic foreset and clayey bottomset beds while the overlying and mainly proximal body is a sub-aerial alluvial fan forming sandy to conglomeratic topset beds.…”

“…According to the same hypothesis, increasing subsequent slip on the NAF has right-laterally offset the late Miocene fold system, by about 70km. Here we focus on better characterizing the link between the NAF and the structures on both sides of it, combining three approaches: (1) we analyze accurately the geology and morphology of Mount Ganos and Gelibolu Peninsula using a high-resolution digital elevation model (DEM with 30 m resolution), satellite imagery and field observations allowing us to build detailed maps and cross sections across the structures clarifying the relationships between sedimentary units; (2) we revise the stratigraphy of sedimentary units by research of calcareous nannofossils, characterized by disappearance and appearance of several species during the time-interval 7-4 Ma (middle Miocene -early Pliocene) encompassing the Messinian Salinity Crisis (MSC;5.97-5.46 Ma;[CIESM, 2008;Manzi et al, 2013;Bache et al, 2012]) which left clear evidence of its impact in the Dardanelles [Melinte-Dobrinescu et al 2009]. That evidence allows us to determine the timing of compressional deformation; (3) we propose a composite cross section reconstructing the possible geometry of the folded structures on both sides of the NAF prior to their right-lateral offset.…”