Biogeography of the Pleistocene pleniglacial malacofaunas in Europe. Stratigraphic and climatic implications
Abstract As determined by Lozek, malacological associations are significant of a particular vegetal environment. In Quaternary sequences, different types of associations are recognized which can be assimilated to the present types of malacofaunas. There are associations of grass group, of forest group and of the ecotone of these two biogeographical entities. On the European scale, in Pleistocene sequences, the interglacial faunas indicate similarly the same differences as today, being of stratigraphic interest. On the contrary, pleniglacial faunas, which are mainly preserved in the loess belt, seemed not interesting for stratigraphy since they indicate more generalized and more homogeneous …
Phylogenèse et biogéographie deRetinella (Lyrodiscus) Pilsbry (Gasteropoda: Zonitidae)
Resume Les especes fossiles (ouest-europeennes) et actuelles (endemiques des Iles Canaries) du sous-genre Lyrodiscus (Neogene — Quaternaire) ont ete revisees sur les memes bases methodologiques. La premiere partie propose un historique de Retinella (Lyrodiscus) et des differents taxons qui lui sont apparentes. Cette revue aborde la creation de Retinella (Riediella) par Schlickum, sour-genre destine a accueillir l'espece Helix jourdani creee par Michaud . La deuxieme partie permet, sur les bases d'une analyse morphologique comparative, de reconsiderer cette attribution generique en rejetant Riedeliella et en proposant d'integrer l'espece de Michaud a Lyrodiscus. Cette confrontation a permis …
A 350,000-year climatic record from the loess sequence of Achenheim, Alsace, France
Up to now the best Quaternary climatic sequences come from oceanic isotope studies, but terrestrial sequences are also well known, usually for pollen or ice core data. A new sequence providing climatic information for the last 500,000 years has been studied in the loess series of Achenheim (Alsace), using the mollusc record in relation to other stratigraphical data. Mollusc assemblages are analysed using a multivariate method. The correspondence analysis used here allows us to explain, in ecological terms, the general variability of the Achenheim set. Most Pleistocene mollusc species have the advantage that modem individuals live in the same assemhlages. So, the known ecology and distributi…
Continental late Pliocene paleoclimatic history recorded in the Bresse Basin (France)
International audience; We present results to show that the Beaune P & C borehole, cored in the Bresse Basin (France), records late Pliocene climatic variations. Pollen analysis allows precise correlations with northern and southern European stratigraphies. Using Kukla et al.'s (1981) climate index, we show that cold climate phases occur during the Brunssumian, at around 3.2, 3.6 and 5.2 Myr B.P., respectively, in agreement with Atlantic core results. The onset of a general cooling trend is felt early in the Reuverian, at about 3 Myr B.P. which corresponds to the end of a warm event characterized by high percentages of oak. This is followed by minor climatic pulses of increasing magnitude s…
Les formations carbonatées du Dortan (Ain) : premières observations
Calcium carbonate, deposits have built four terraces, near Dortan, in the Southern part of Central Jura (46° lat. N). These deposits may just cover other terraces associated themselves with an ice-dammed lake. They include two types : 1) tufa deposits, porous and hard, with conspicuous tree remains ; 2) lake chalk, compact and brittle, snowing lenses and, sometimes, varves, with shells and pieces of charcoal. C 14 dating and analyses should allow to insert these deposits in the Jura Holocene chronology and to explain their situation at such a high latitude.
Aegopinella bourdieri nov. sp. (Gastropoda: Zonitidae),une espèce nouvelle du Pléistocène normand (France)
St Pierre-les-Elbeuf (Normandy, NE France) is a reference site for the middle and the upper Pleistocene of NW France. In the eastern part of the quarry, the paleosoils Elbeuf III and IV are truncated, white sands and a small tufa lay on Elbeuf IV. Similar deposits have been recognized at Vernon (Seine valley) and at Arrest (northern France). They are probably contemporaneous (Holsteinian) and each of them has yielded an interglacial malacological fauna. The faunal communities are interesting because they are composed by species living up to now in this country, by emigrated species and by fossil species. Among them, A. bourdieri is a new fossil taxa, endemic of Holsteinian tufas of Normandy…
HOLOCENE CLIMATE AS REFLECTED BY A MALACOLOGICAL SEQUENCE AT VERRIERES FRANCE
Though numerous analyses have been made of Holocene pollen sequences, they come from similar environmental contexts, mainly peat deposits. Land snails can provide good palaeoecological and palaeoclimatical data in different drier environmental settings. The Verrieres deposits, located in the Seine Valley, southeast of Paris, provide rich and abundant malacofaunas. We compare the well–defined local biostratigraphy with other mollusc stratigraphies from Burgundy, the closet site to the studied region. Multivariate analysis of the malacofaunas indicates that temperature and moisture did not always vary in parallel during the Holocene. On the other hand, Verrieres malacofaunas reflect the main …