Les foraminifères planctoniques du Néogène du bassin de Boudinar (Rif nord-oriental, Maroc)‎. Biostratigraphie, systématique et paléoécologie

The planktonic foraminifers from the Neogene series of the Boudinar basin (northeast of Morocco) show both high specific diversity and numerical abundance and specific have therefore good potential for biostratigraphical, palaeoecological and systematic studies.64 species have been recognized, the systematic description of all the taxa is given as well as stratigraphical, distributional and ecological data.New subzones within the Neogene series tentatively introduced based on foraminifer distribution through the Neogene series of the Boudinar basin. A more accurate definition of the Tortonian - Messinian boundary and the limit between Miocene and Pliocene is proposed. Bioevents are recognized.Quantitative methods (planktonic / benthic ratio) were used together with through morphological studies. The distribution of planktonic foraminifers seems to have much controlled by the water depth, the temperature and the salinity. Detailed studies from selected profiles hitting the basin indicate significant variation in the thickness of the water column during the Messinian times.Palaeogeographical implications are tested against current models proposed for the Neogene of the Mediterranean regions.Les foraminifères planctoniques du Néogène du bassin de Boudinar (NE du Maroc) montrent une grande richesse en espèces et en individus. Ils offrent un matériel intéressant pour une étude biostratigraphique, systématique et paléoécologique.Soixante-quatre espèces ont été déterminées et étudiées. La description morphologique de chaque espèce est complétée par des données d’ordre stratigraphique, géographique et écologique.L’étude biostratigraphique de la série néogène de ce bassin, basée sur ces organismes, a permis d’une part de distinguer de nouvelles sous-zones et d’autre part de préciser certaines limites (la limite Tortonien-Messinien et la limite mio-Pliocène) et de les caractériser par un ensemble de bio-évenements.Les données de l’étude systématique sont ensuite associées aux résultats quantitatifs, semi quantitatifs et qualitatifs obtenus à partir des comptages et complétées par les renseignements fournis par le rapport planctono - benthique (P / P+B). L’analyse paléoécologique des assemblages à foraminifères planctoniques révèle que ceux-ci se différencient notamment en fonction de la profondeur, de la température et de la salinité. L’étude détaillée de ces assemblages dans plusieurs coupes met également en évidence une instabilité dans l’épaisseur de la tranche d’eau dans le bassin de Boudinar au cours du Messinien.Les considérations précédentes développées ont enfin permis d’aborder l’aspect paléogéographique et de replacer les assemblages étudiés dans leur contexte méditerranéen et néogène

Evidences of pre-Zanclean marine refolding of the Mediterranean Basin

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Les épisodes Lago Mare associés à la Crise messinienne

International audienc

Les épisodes Lago Mare associés à la Crise messinienne

International audienc

Reply to the comment on the paper "Lago Mare and the Messinian Salinity Crisis: Evidence from the Alboran Sea (S. Spain) by Do Couto et al. (2014) Marine and Petroleum Geology 52 (57–76)" authored by Serrano and Guerra-Merchán

The marine context of the Lago Mare deposit near Malaga has received agreement as well as its ascription to the third Lago Mare event of Clauzon et al. (2005). This deposit is not a “transitional unit towards normal marine conditions” but followed the marine reflooding of the Mediterranean Basin, allowing the connection with the Dacic Basin (Eastern Paratethys). We show that this Lago Mare event did not result from a climatic change leading to a dilution episode but from a high sea-level connection. Different interpretations on the respective effects of tectonics and eustatism on the sedimentary archives linked to the Messinian Salinity Crisis (MSC) are once more debated. They depend on (1) the duration assigned to the MSC and its subdivisions, (2) the amplitude of the successive sea level variations, and at last (3) the dimensional (local or regional) view of the MSC. Such discrepancies concern subsidiary matters which cannot mask first order facts and progresses in their knowledge

Lago Mare episodes around the Messinian–Zanclean boundary in the deep southwestern Mediterranean

International audienceWe present a high-resolution analysis of planktonic foraminifers, calcareous nannofossils, ostracods, dinoflagellate cysts and pollen grains in four sequences from DSDP–ODP holes in the southwestern Mediterranean Alboran and Balearic basins (976B, 977A, 978A and 134B) encompassing the previously defined Messinian–Zanclean boundary. The study focuses on (1) the marine reflooding, which closed the Messinian Salinity Crisis prior to the Zanclean GSSP; (2) the nature of the Lago Mare in the deep basins (indicated by Paratethyan dinoflagellate cysts), which appears to comprise several Paratethyan influxes without climatic control; and (3) the depositional context of the youngest Messinian evaporites which accumulated in a marine environment relatively close to the palaeoshoreline. Isolation of the Aegean Basin during the paroxysmic second step of the crisis is considered to have stored Paratethyan waters, which may then have poured into the Mediterranean central basins after deposition of the evaporitic sequence

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. As a result, changes in gateway geometry can significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound impact on local environmental conditions. Mediterranean–Atlantic marine corridors that pre-date the modern Gibraltar Strait, closed during the Late Miocene and are now exposed on land in northern Morocco and southern Spain. The restriction and closure of these Miocene connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the precipitation of thick evaporites. This event is known as the Messinian Salinity Crisis (MSC). The evolution and closure of the Mediterranean–Atlantic gateways are a critical control on the MSC, but at present the location, geometry and age of these gateways are still highly controversial, as is the impact of changing Mediterranean outflow on Northern Hemisphere circulation. Here, we present a comprehensive overview of the evolution of the Late Miocene gateways and the nature of Mediterranean–Atlantic exchange as deduced from published studies focussed both on the sediments preserved within the fossil corridors and inferences that can be derived from data in the adjacent basins. We also consider the possible impact of evolving exchange on both the Mediterranean and global climate and highlight the main enduring challenges for reconstructing past Mediterranean–Atlantic exchange