9th Symposium on Oceanography & Fisheries, 2009 - Proceedings, Volume Ι AN EARLY PLEISTOCENE MOLLUSC FAUNA WITH PONTO-CASPIAN ELEMENTS, IN INTRA HELLENIC BASIN OF , ΑRKITSA REGION (CENTRAL )

Koskeridou E.1, Ioakim Chr. 2 1 Geology & Geoenvironment Dptm., National and Kapodistrian University of , [email protected], 2 Institute of Geology and Mineral Exploration, [email protected] Abstract The main goal of this research is to define the palaeoenvironmental conditions featuring the Pleistocene sediments of Arkitsa region in Atalanti Basin (), based on the study of molluscs and palynomorphs. The effort for the palaeoen- vironmental and palaeoclimatic reconstruction of this area, comparing previous studies, leads to the conclusion that this brackish-fresh water basin was from time to time isolated from the Aegean, being however very close to the sea level. The study of the fauna leads to a comparison of this basin with equivalent Ponto-Caspian brackish basins provides evidence of wide communications between these basins and the Mediterranean through Marmara Sea –DardanellesStraits, during Early Pleistocene.

Keywords: pleistocene, lacustrine, molluscs, palynomorphs, central Greece. Introduction The slow supra-species level evolution of nonmarine molluscs permits interpretation of paleoen- vironments from the environmental constraints of taxonomically similar modern representatives. Therefore, nonmarine fossil molluscs provide a valuable paleoecological tool for understanding ancient depositional environments and their spatial and temporal distributions. This enhanced un- derstanding of paleoenvironments combined with lithostratigraphy allows interpretation of the cli- matic and tectonic conditions that affected the brackish to fresh water systems of the past. The palynological analysis of the sediments is important in order to reconstruct the past vegetation, to get interesting information about the palaeoenvironment and the climatic conditions during the Neo- gene -Quaternary, to correlate the deposits and assign tentative data. The utility of nonmarine molluscs for palaeoenvironmental reconstruction together with palyno- logical analysis, is applied to the Arkitsa region (in Atalanti Basin) Εarly Pleistocene lacustrine and shallow marine deposits. Εarly Pleistocene mollusc fauna from this area was described by Fuchs (1877) and Gillet et al. (1978). Arkitsa section, gave us the opportunity for a detailed qualitative study of the contained mollusk fauna and particularly the ecological preferences of species and the changes in their composition in order to use them as indicators of palaeoenvironment. 2. Geological outline Atalanti basin is located in Lokrida region (Fig. 1) and is covered in a big part, by Plio-Pleis- tocene sediments and Holocene alluvium. The faults that mark the borders of Atalanti channel are of high throw, a fact that gives an explanation of the big thickness of the Quaternary and Holocene sediments. The alpine basement of the area belongs to the Subpelagonic zone and it has been studied by Marinos et al. (1957) and Celet (1962). The Neogene sediments are mainly represented by lacustrine and shallow marine sediments of Pliocene and Pleistocene age and consist of marls, clays, sandstones, conglomerates and marly lime- stones. Neogene sections in the area have been studied in the past by Fuchs (1877), Guernet (1971), Pechoux et al. (1973), Philip (1974), Keraudren (1975), Gillet et al. (1978), Rondoyanni-Tsiambaou (1984) and Ioakim & Rondoyanni (1988). Arkitsa section contains a detritic lake periodically flooded series, which is covered by the up-

-96- 9ο Πανελλήνιο Συμπόσιο Ωκεανογραφίας & Αλιείας 2009 - Πρακτικά, Τόμος Ι permost limestone, with an angular unconformity. This pass from the detritic series to the limestone -represented by an erosional surface and a discordance-, at the top of the section, probably marks a regression due to the evolution of the basin and the synsedimentary tectonic activity. 3. Material and Methods Molluscan faunas were examined in a number of samples recovered from the studied succession (Fig. 2). The benthic fauna was separated from the terrigenous fraction using a 0.5 mm sieve for molluscs. The molluscs, were classified to species level, using the descriptions based on numerous works by molluscan researchers (Tournouer, 1876; Fuchs, 1877; Newton, 1911; Willmann, 1981). Then, they were qualitatively analyzed and an estimation of the number of specimens of each species was made. The palaeoecology of molluscan associations compined with the lithostratigraphy led to the paleoenvironmental interpretations. Also, the preliminary palynological results from the Arkitsa region are presented. The mate- rial were collected from the brackish deposits of the section and was examined in relation to the results obtained from several sections in Locride. Standard palynological prosedures were used in the preparation of each sample. 4. Results

4.1. LITHOLOGICAL SEQUENCE OF ARKITSA SECTION Arkitsa outcrop section is situated in a road trench north of Arkitsa town, between the National Highway and Arkitsa ferry boat station (Figs 1, 2). The layers form monocline with inclination 10-15 SE. It comprises of approximately 50 meters of lacustrine sediments. The section consists of two units. The lowermost part of the first unit of the section consists of fine, yellow, bedded sand of 1.2m thickness. This is overlain by 1m of shelly, fine to coarse reddish-yellow bedded, with lenses of green clay. Abundant very well preserved freshwater molluscs, as Unio (Eolymnium) sp., Dreissena poly- morpha PALL., Theodoxus carinatus FUCHS, Theodoxus micans GAUDRY & FISCHER, Vivipara megarensis (FUCHS), Valvata philippsoni OPP., Valvata piscinalis (MULL.), Adelinella elegans (CANT.), Lymnaea sp., Acella megarensis (GAUDRY & FISCHER), Micromelanea sp., Hydro- bia transitans NEUM., Pyrgula incisa FUCHS, Pyrgula gigantica GILLET, Pyrgula tricarinata FUCHS, and fragments of Crassiana sp., are contained in this horizon.

Fig. 1: Location of the Arkitsa section in Locride region (Google Earth).

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Fig. 2: Lithological column of Arkitsa section.

Upwards these layers pass into 3.5m of clayey fine yellow sand with marly intercalations, con- taining poor associations of molluscs and particularly, Dreissena polymorpha PALL. and Pyrgula incisa FUCHS. The former layers are overlain by some 2.2 m of brown-yellow fine to coarse sand with clayey sand intercalations. At the base of this bed, there is a layer of shelly sand. A rich molluscan assem- blage has been collected from this bed: Dreissena polymorpha PALL., Theodoxus micans GAUDRY & FISCHER, Vivipara megarensis (FUCHS), Adelinella elegans (CANT.), Acella megarensis (G. et F.), Pyrgula incisa FUCHS, Pyrgula tricarinata FUCHS and fragments of Crassiana sp. Upwards in the section bedded clays and sand of 4.5m thickness, are present. These are over- lain by some 1.2m of shelly and clayey intercalations, containing shells of Dreissena polymorpha PALL. A 0.2m thick lence of light-grey diatomites follows. The section continues with almost 5m clays and sand and passes into 1m green, bedded shelly clays, with large shells of Dreissena poly-

-98- 9ο Πανελλήνιο Συμπόσιο Ωκεανογραφίας & Αλιείας 2009 - Πρακτικά, Τόμος Ι morpha PALL. and Vivipara megarensis (FUCHS), Valvata piscinalis (MULL.), Adelinella elegans (CANT.), Pyrgula incisa FUCHS. This horizon is overlain by brown-yellow bedded clays and silty clays of 5,2m thickness. It contains large shells of Dreissena polymorpha Pall. Upwards a 0,5m thick brown coarse sandstone horizon without shells appears. It is overlain by yellow-brown clays and silty clays of 4m thickness and it is characterized by the intense presence of Dreissena polymorpha PALL. This horizon passes upwards into 0,6m of gray-brown sandstone. The section continues with 4,5m of sand and silt with lenses of CaCO3. Upwards it passes into 3-4m yellow sand with reddish patches-roots of red fossil soil. The top of the first unit of the section consists of red sand which is possibly fossil soil with erod- ed surface. The thickness of this layer is about 2-3m. At the top of this horizon an erosional surface was observed. The uppermost limestone covers the detritic lake series with an angular unconformity and forms the third unit of the section. This limestone is light grey, soft, with reprints of fresh water mollusc shells of Limnaea sp., Planorbis sp. The thickness of this horizon is about 1.5-2.5m. 4.2. PALYNOLOGY The microfloral assemblages are composed of pollen grains of a rich vegetation, where trees and herbs are represented. Generally they are characterized by high percentages of Pines, a very low abundance of Cupressaceae, high percentages of herbaceous and the fairly continuous presence of pollen grains representative of Mediterranean evergreen plants. Particularly, the palynological assemblages are composed by a rich association of Pinaceae pre- dominates (Pinus type especially, Cedrus and Abies) followed by the sclerophyllous angiosperms, Quercus ilex, Olea, Cistus and less by species such as Alnus, Carya, Eucommia, Ulmus/Zelkova, Platanus, Myrica, etc. The herbaceous angiosperms are well represented by Amaranthaceae-Chenopodiaceae, Gram- inae, Compositae, Umbelliferae, Ericaceae, accompanied by the ferns of Pteridophyts. Also these assemblages containing various cysts of dinoflagellate such asGonyaulacysta adapted in a brackish environment. 5. Discussion The molluscs fauna of this section consists of common species appearing in Livanates-Arkitsa sections, as well as some species of the section of Yaltra in north- west of Euboea (Gillet et al. (1978). It contains recent species and extinct endemic elements as Adelinella, Pyrgula, Theodoxus, etc. New elements from this section as Crassiana sp. and Unio (Eolymnium) sp., have been also collected. The alternation of coarse and fine sediments wich are characterised by the presence of different species of molluscs possibly indicates the lake and sea level oscillations. The reophil freshwater molluscs (as Lymnaea sp. and Vivipara megarensis) indicate littoral and nearshore facies and the regressions at the area, while on the contrary, the presence of forms which characterize deeper environments as the presence of Dreissena, indicate the transgression. The presence in the area of Dreissena, and Didacna which are Caspian brackish water elements, indicates a connection of this lagoon with the Aegean Sea. It is possible, that brackish molluscs mi- grated from the Black Sea brackish water basins as Gurian and Tchaudien, through the Aegean Sea, to the lacustrine basin of Atalanti, where they were preserved. The presence at the studied section of Adelinella elegans (CANT.) which is a caspian feature and has been described in Apscheronian of Russia, is characterising the Early Pleistocene. Neogene sections in this area have been studied by Keraudren and also by Fuchs (1877) and Gil-

-99- 9th Symposium on Oceanography & Fisheries, 2009 - Proceedings, Volume Ι let et al. (1978), who have characterised these deposits as Bakiniennes and Tchaudien respectively using the presence of Didacna spratti Fuchs. The palynological analysis and relevant comparisons with the equivalent associations in Locride area and Yaltra in north- west of Euboea Island (Gillet et al.1978; Philip et al,1974; Rondoyanni- Tsiambaou 1984; Ioakim & Rondoyanni 1988) suggest that the above sediments could be deposited during the Early Pleistocene. An open forest development existed at Locride during the Lower Pleistocene, considering the general representation of temperate forest elements and the very important representation of herba- ceous. The composition of the prenoted elements resembles with those obtained from Zeli lacustrine deposits in Locride basin (Ioakim & Rondoyanni 1988), characterized by a vegetal assosiation of sclerophyllous elements, with Quercus ilex-coccifera, Olea, Cistus accompanied by the mountain trees, showing comparable characteristic in temperature and dryness according to the representative elements. 5. Conclusions During Early Pleistocene, a brackish fresh water Intra-Hellenic basin formed, between Euboea Island and the continent. This basin was from time to time isolated from the Aegean Sea and periodi- cally flooded. The mollusc associations contain some endemic fresh and brackish-water species. This is an evidence that further supports the isolation of this basin. New elements as Crassiana sp. and Unio (Eolymnium) sp., have been also collected. There are some species as Adelinella elegans (CANT.) and Dreissena polymorpha PALL., which show a connection between Atalanti Basin and the Ponto-Caspian brackish basins, as Gurian, Tchau- dien and Apsheronian, supporting the idea that maybe there was wide communication between these basins and the Mediterranean through Marmara Sea -Dardanelles, during Early Pleistocene. Finally, the composition of the Early Pleistocene pollen flora, suggests the existence of an open temperate forest in the area. 6. Acknowledgements We express our gratitude to the University of Athens for supporting us financially to carry out this research (Research Project 70/4/5849). 7. References Andrusov, N.J., 1923. Etage apschéronien. Mém. Co., Géol. URS, N.S,. 110:569 pp. Celet, P., 1962. Contribution a 1’etude geologique du Parnasse-Kiona et d’une partie des regions meridionales de la Grece continentale: Analles Geol. Pays Hellen., 13 : 1446 pp.. Fuchs, Th., 1877. Studien uber die jungeren Tertiarbildungen Griechenlandes. Denkschr. K. Akad. Wissensch. Math. –not. Ci. Wien, XXXVII (2): 1-42. Gillet, S., Sauvage, J. & Keraudren, B., 1978. Etude paléontologique du Plio-Pléistocène de Locride et d’ Eubée occidentale (Grèce centrale): Malacologie et Palynologie. Ann. Géol. Pays Héllèn., Athènes, 29: 554-580. Guernet, C., 1971. Etudes géologiques on Eubée et dans les régions voisines (Grèce). Thèse, Fac. Sci. Paris, 395pp. Ioakim, C. & Rondoyanni, Th., 1988. Contribution à l’étude géologique de la région de Zeli, Locride (Grèce Centrale). Révue de Micropaléontologie, 31(2) : 129-136. Keraudren, B., 1975. Essai de stratigraphie et de paléogéographie du Plio-Pléistocène égeen. Bull. Soc. Géol. Fr. (7), XVII, 6: 1110-1120. Marinos, G. et collaborateurs –1957-1967. Geological map of Greece 1/50.000. Newton, R.B., 1911. On the Modifications in Form of the Upper Tertiary Lacustrine Shells of the Island of Cos, as First Observed by Edward Forbes and T.A.B. Spratt.- Prec. Mal. Soc. London 9: 363-368. Oppenheim, P., 1891. Beitrage zur Kenntnis des Neogen in Griechenland. Z. dt. Geol. Ges., 43: 421-487.

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Pechoux, P.Y., Pegoraro, O., Philip, H. & Mercier, J., 1973. Deformations mio-pliocènes et quaternaires en extension et en compression sur les rivages du golfe maliaque et du canal d’ Atalandi (Egée, Grèce). –C. R. Acad. Sci. Paris, 276 (D) : 1813-1816. Philip, H., 1974. Etude néotectonique des rivages égeens en Locride et Eubèe nord-occidentale (Grèce) –Thèse doctorat de spécialitè U.S.T.L. Montpellier, 78pp. Philip, H., Keraudren, B., Mercier, J., Pechoux, P.Y. & Sauvage, J., 1974. Néotectonique polyphassé dans le bassin égeen (Eubèe, Locride, Grèce). 2ème Reunion Sci. Terre, Soc. Géol. Fr., Paris. Rondoyanni-Tsiambaou, TH., 1984. Etude néotectonique des rivages occidentaux du canal d’ Atalanti (Grèce centrale). Thèse 3ème cycle, Univ. d’Orsay, 190pp. Tournouer, R. 1876. Etude sur les fossils tertiaires de l’ île de Cos. Ann. Scient. école norm. Sup. sér. 2,5: 445-475, Paris. Willmann, R., 1981. Evolution, Systematik und stratigraphische Bedeutung der neogenen Süswassergastropoden von Rhodos und Kos/Ägäis. Palaeontographica A 174: 10-235, Stuttgart.

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