Dimitris Frydas

Plankton stratigraphy and some remarks on Globorotalia evolutionary trends from the Plio-Pleistocene sections of southwestern Peloponnesus, Greece

The Pliocene-Pleistocene boundary of the Androussa section is indicated by the last occurrence of Discoaster brouweri and D. triradiatus, the presence of Calcidiscus macintyrei, and the first appearance of Gephyrocapsa caribbeanica (NN19a). Hyalinea balthica is an important index fossil in the lower Pleistocene deposits of the Elea section where it appears together with Gephyrocapsa oceanica and other small Gephyrocapsa spp. (NN19b). A transitional form between the upper Pliocene foraminifera species Globorotalia bononiensis and G. inflata is recognized based on statistical analysis of apertural development. In this transitional form, apertural length is a reliable indicator of evolutionary closeness to G. inflata rather than G. bononiensis. INTRODUCTION The stratigraphical distribution of Plio-Pleistocene deposits in the Peloponnesus has previously been investigated using calcareous nannofossils (Frydas 1987, 1989b, 1990, 1993), and the nannoplankton biozones have been correlated with the biozonation of planktic foraminifera. The northwestern and western Peloponnesus is mainly dominated by lagoonal to lacustrine deposits. Marine sediments are rare in this area and when present are normally faulted (Hagemann 1979; Frydas 1987, fig. 2). The fossil nannoplankton assemblages from the NW-Peloponnesus sections have been assigned to Piacenzian age, in the interval of NN16 to NN18 biozones (Frydas 1987, 1989b). Marine deposits occupy extensive areas in the southwestern Peloponnesus, where continuous sedimentation from the lower Pliocene biozone NN13 to the lower Pleistocene biozone NN19b has been observed (Frydas 1990). In the southeastern Pelopponesus, lower Pleistocene marine deposits near the coast have been placed in biozones NN19a and NN19b (Frydas 1993). The sedimentology and the tectonic development of southwestern Peloponnesus have been studied by Kontopoulos (1978) and Zelilidis (1989). According to them the following principal lithofacies can be distinguished from younger to older: Reddish terrestrial conglomerate and sandy gravels; Mainly yellowish lagoonal fossiliferous sands and barren delta front sands alternating with sandy silts; Grayish silt and sandy silt fossiliferous lithofacies. These strata were deformed in half grabens that opened during back-arc extension of the Hellenic trench (Zelilidis and Doutsos 1992). In this work both the nannoplankton assemblages from standard sections and index planktic foraminifera species have been evaluated. In particular, the evolutionary trends of Globorotalia bononiensis and Globorotalia inflata were investigated. Emphasis was given to the stratigraphical distribution of the planktic foraminifera species and the transitional form between them. A morphometric study which follows the biostratigraphical analysis demonstrates clearly the evolutionary trend from G. bononiensis towards G. inflata. The extensive literature on the geology and stratigraphy of the Neogene of Peloponnesus, in which the paleontology is mainly concerned with macrofossils, has been previously discussed by Frydas (1987 to 1993). Correlation of the Peloponnesus Neogene TEXT-FIGURE 1 Location of studied sections in the Peloponnesus. 1: Kastro(Patras); 2, 3: Vrachneika; 4: Aghia Marina; 5: Simisa; 6: Kyllini; 7: Kyllini(camping); 8, 9: Koroni-road(a,b); 10: Rizomylos; 11: Avramion; 12: Androussa; 13: Spitali; 14: Thouria; 15: Stenossia; 16: Kremmidia; 17: Polylofos; 18: Kalamata; 19: Kokkinia; 20, 21: Elea; 22: Neapolis. micropaleontology, vol. 40, no. 4, pp. 322-336, text-figures 1-9, plates 1-2, tables 1-4, appendix 1, 1994 322 This content downloaded from 207.46.13.139 on Thu, 27 Apr 2017 17:50:27 UTC All use subject to http://about.jstor.org/terms Micropaleontology, vol. 40, no. 4, 1994 TEXT-FIGURE 2 TEXT-FIGURE 3 Location of Rizomylos section. Location of Androussa section. to the biostratigraphic zonal scheme developed for the eastern Mediterranean by Ellis and Lohman (1979, DSDP Leg 42A) is discussed elsewhere (Bellas and Frydas, in press). In addition, a number of the most important Pliocene-Early Pleistocene sequences in different areas of the northern Mediterranean basin, especially in Italy, were discussed by Ioakim et al. (1990). The aim of the present paper is the investigation of the Pliocene/Pleistocene boundary in the southern Peloponnesus (text-fig. 7).

Paleoecology, stratigraphy and taxonomy of the pliocene marine diatoms from central crete (Greece)

Abstract A rich siliceous phytoplankton assemblage of late Early Pliocene to early Late Pliocene age, containing 31 genera of marine diatoms with 55 specific taxa, was found in fine laminated diatomite beds in the sections of Kallithea, Marathitis, Prassas and Aitania from the northern central part of the Crete Island (Province of Heraklion, Greece). The sediments of the studied sections belong to the upper part of the Stavromenos facies-unit (Early to Late Pliocene). The diatom associations were mainly investigated for their paleoecology, stratigraphy and taxonomy. The diatom assemblages are characterized by species typical of low latitudes. They belong to the upper part of the Nitzschia jouseae biozone (Early Pliocene — Late Pliocene) because of the presence of the marker species N. jouseae, which is rare to frequent in the Kallithea and the Marathitis sections, and rare in the Prassas and Aitania sections. The upper part of the N. jouseae biozone corresponds to the CN11b (Discoaster asymmetricus) and CN12a (D. tamalis) subzones of calcareous nannofossils as well as to the Globorotalia puncticulata and Gl. bononiensis biozones of planktic foraminifera. Among the diatoms the planktie, centrie species dominate in terms of their percentage distribution and reflect a succession of two paleoclimate intervals : a subtropical interval with the warm-water species Azpeitia nodulifer, Hemidiscus cuneiformis and Thalassiosira leptopus and a temperate interval characterized by the cold-water species Coscinodiscus marginatus. These two intervals are proposed as two new local acme subzones.

Evolutionary trends of the pliocene silicoflagellate group Dictyocha fibula from Marathitis section, central Crete (Greece)

Abstract A rich opal phytoplankton assemblage of Upper Zanclean to Lower Piacenzian age, containing diatoms and silicoflagellates, occurs in finely laminated diatomite beds in the north-central part of the Island of Crete (Marathitis section, Heraklion District, Greece). We are here mainly concerned with the stratigraphic distribution and evolutionary trends of the Dictyocha fibula silicoflagellates group. In addition to the two well established subspecies Dictyocha fibula ausonia ( Deflandre ) and Dictyocha fibula mutabilis ( Deflandre ), identified in our material, two new species/subspecies — Dictyocha hellenica n.sp. and D. fibula minos n.subsp.— are here described for the first time. Their distinction is also supported by a statistical analysis of morphometric data concerning the length (L) and width (W) of the inner diameter of both the major and minor axes, the L/W ratio, radius of curvature (Cr) and lateral portal diameter (dlp) of these taxons.

Phytoplankton-stratigraphy from neogene, marine depositions near ierapetra, crete, Greece

KurzfassungDas kalkige und kieselige Phytoplankton aus dem Neogen der Insel Kreta/Griechenland (Südägäischer Inselbogen) wurde lichtmikroskopisch auf seine stratigraphische Verbreitung untersucht. Dabei war es möglicn, 13 Arten von Silicoflagellaten und 22 Arten von Diatomeen studieren zu können. Das untersuchte Material vom Profil Tsikalaria wurde in dieDistephanus boliviensis- sowie in dieDiscoaster tamalis-Zone eingestuft (basales Oberpliozän).AbstractThe fossil calcareous and siliceous phytoplankton occurring in the Neogene of the island of Crete — Greece — (South Aegean island arc), was studied using normal ligntmicroscopic techniques. By this method it was possible to identify 13 species of the silicoflagellates and 22 species of the diatoms, which are investigated in this work for their stratigraphical range. The nannoplankton assemblages along the locality from Tsikalaria belong to theDistephanus boliviensis and theDiscoaster tamalis zone (early Upper Pliocene).

The Oligocene Argyrotopos profile in the external lonian basin (Epirus, Greece): Microfacies and microfossils

SummaryThe Argyrotopos profile of the Oligocene Ayii Pantes Formation in the NW Greece was studied using litho- and biofacies-analysis. The exposed sequence is mainly composed of monotonous marls and sandy marls. A rich fossil content, e.g. calcareous nannoplankton, is recorded. Some sandstone beds and two graded limestone beds with abundant lepidocyclinids and globigerinids are intercalated. The nannofossil assemblages from the measured profile of the Ayii Pantes Formation are attributed to theSphenolithus distentus Zone (NP 24) which is equivalent to theCyclicargolithus floridanus Subzone (CP 19a) of the Chattian, Upper Oligocene. The deposition took place in an euphotic subtidal environment situated on the eastern margin of the Apulian Platform. The lepidocyclinids were derived from this platform and were transported basinwards. The formation of the marls is influenced by sediment flux from the west.