Fish otoliths from the Pliocene Heraklion Basin (Crete Island, Eastern Mediterranean)

The Pliocene Eastern Mediterranean fish record is revealed through the study of a 60-m thick stratigraphic sequence near the village Voutes (Heraklion, Crete). Forty-two species belonging to twenty families are identified. Calcareous nannoplankton biostratigraphy places the studied sequence within the biozone MNN16a (latest Zanclean). The stratigraphic distribution of 31 species is modified. Among these, 12 species are reported for the first time in the Eastern Mediterranean Zanclean, while 19 species are first reported outside the Ionian Sea. The Voutes fish fauna presents a diversified benthic and benthopelagic assemblage filling a significant gap in the fossil record

Evaluating the effect of marine diagenesis on late Miocene pre-evaporitic sedimentary successions of Eastern Mediterranean Sea

Unidad de excelencia María de Maeztu MdM-2015-0552The microstructure and geochemical composition of foraminiferal tests are valuable archives for the reconstruction of paleoclimatic and paleoecological changes. In this context, the late Miocene Globigerinoides obliquus shells from Faneromeni section (Crete Island) were investigated through Scanning Electron Microscopy (SEM) imaging, Energy Dispersive System (EDS) analysis and X-Ray Diffraction (XRD) spectroscopy in order to evaluate their potential as paleoenvironmental archives in the eastern Mediterranean. Investigation of diagenetic features, in late Miocene sediments from the Faneromeni section, shows that carbonate precipitation and cementation occur in various lithologies, particularly in carbonate-rich portions, such as bioclastic or clayey limestones. We identified 3 different diagenetic stages (early, intermediate, advanced), as a function of taphonomy in the study area. The comparison of microstructural and geochemical characteristics reveals a sequence of preservation states with "glassy" to "frosty" to "chalky" shells, indicative of the progressive diagenetic alteration of late Miocene planktic foraminiferal calcite. The early diagenetic stage occurs during the Tortonian, and consists of intermediates between "glassy" and "frosty" individuals. Around the Tortonian/Messinian (T/M) boundary at the second diagenetic stage, planktonic foraminifera have a clear "frosty" appearance, showing a gradual high-Mg calcite (to dolomite) crystal overgrowth development and dissolution of biogenic calcite. During the late Messinian and progressively through the Messinian Salinity Crisis (MSC), planktonic foraminifera present a "chalky" taphonomy. The additional precipitation of authigenic high-Mg inorganic calcite and dolomite crystals in the exterior of the tests characterizes the advanced diagenetic stage. The measured amount of diagenetic Mg-rich (10-14% molar Mg on average) calcite and/or dolomite coatings is compatible with results obtained on modern eastern Mediterranean core-top sediments. The assessment of such a diagenetic alteration contributes to a more precise reconstruction of sea surface temperatures (SSTs) during the Neogene, such that only when the changing proportions of the texture are accounted for, would geochemical measurements and subsequent paleoenvironmental interpretations be more meaningful. However, further investigations should extend this approach to test the robustness of our findings across a range of taphonomies, ages and burial settings

Faunes de bryozoaires à la limite Tortonien-Messinien. Étude de cas des paléoenvironnements de l’île de Crète, Méditerranée orientale

Quatre coupes lithostratigraphiques ont été levées et échantillonnées dans les affleurements du Tortonien supérieur-Messinien inférieur de l’île de Crète (Grèce). Le matériel prélevé a livré environ 60 espèces de bryozoaires appartenant à neuf morphotypes coloniaux différents. Quelques espèces sont sténobathes, indiquant des environnements littoraux ou profonds, mais la plupart sont eurybathes, avec des intervalles bathymétriques s’étendant parfois depuis le plateau continental jusqu’à plusieurs centaines de mètres de profondeur. Les communautés de bryozoaires révèlent des variations du niveau marin modulées par la tectonique locale. Des environnements du circalittoral profond sont reconnus à la base de trois des coupes (mais la quatrième coupe commence par l’infralittoral/circalittoral côtier, passant ensuite au circalittoral profond). Des habitats du bathyal supérieur apparaissent ensuite, suivis d’assemblages indiquant le circalittoral profond, puis le circalittoral côtier/infralittoral. Ces fluctuations bathymétriques sont fortement diachrones à travers l’île. Des espèces littorales sont par ailleurs associées, parfois en grand nombre, avec de plus rares faunes profondes dans quelques niveaux où elles ont été transportées par des courants. Plusieurs épisodes dysoxiques ont été également identifiés, résultant probablement d’une stratification croissante de la colonne d’eau et d’une augmentation de la productivité organique. Ces processus ont été vraisemblablement favorisés par une combinaison de changements dans la circulation océanique, le climat, le niveau marin global et la tectonique locale/régionale (en Crète et/ou au niveau des corridors marins entre la Méditerranée et l’Atlantique).Four sedimentary sections were logged and sampled from upper Tortonian-lower Messinian outcrops on the island of Crete (Greece). The collected material yielded about 60 bryozoan species belonging to nine different colonial morphotypes. A few species are stenobathic, indicating either shallow- or deep-water environments, but most of them are eurybathic (with bathymetric ranges extending in some instances from the shelf down to several hundreds of metres). Bryozoan communities point to sea-level variations modulated by local tectonics. Deep circalittoral environments were recognized at the base of three sections (whereas the fourth section starts with infralittoral/shallow circalittoral environments passing to deep circalittoral. Shallow bathyal habitats follow upwards, succeeded in turn by assemblages indicative of deep circalittoral and subsequently shallow circalittoral/infralittoral depths. Inferred bathymetric fluctuations are diachronous throughout the island. Shallow-water species found associated, sometimes abundantly, with rarer deep-water faunas in a few levels, are interpreted as transported by currents. Several dysoxic episodes have been also detected: likely the result of water column stratification and enhanced productivity. These processes were probably boosted by a combination of changes in oceanic circulation, climate, global sea-level, and the local/regional tectonics (in Crete and/or the marine gateways between the Mediterranean and the Atlantic).</p

The first plant megafossil in the Early Jurassic of Greece: Brachyphyllum (Coniferales) from the Lower Posidonia Beds (Toarcian) in the Ionian zone (NW Greece) and its palaeogeographic implications

General information on the geology of the Lower Jurassic in the Hellenides is presented, focused on the Chionistra section, where the first land plant macrofossil was recovered. This specimen is interpreted as a new record of Brachyphyllum elegans (SAPORTA) BARALE and compared with the type material from the Upper Jurassic of France and some other Mesozoic fossils of this kind from Eurasia. Its stomatal complexes with papillate subsidiary cells and the co-occurrence with abundant Classopolis pollen indicate an affinity to the Cheirolepidiaceae. The reconstructed environment usually assigned to the Brachyphyllum nepos type may suggest mangrove-like vegetation that thrived under tropical-subtropical climatic conditions. Moreover, the finding of Brachyphyllum elegans (SAPORTA) BARALE from the Lower Jurassic (Toarsian) of western Greece provides confirmation of the palaeogeographic evolution model of the Ionian zone during this period