Les assemblages de diatomées du bassin messinien de Boudinar (Maroc nord-oriental)

The Messinian is one of the strongest biogenic silica accumulation periods in the world and more particularly in the Mediterranean, where it is marked by an important diatomitic sedimentation. In the Boudinar basin (Morocco north-Eastern, Western Mediterranean), the section of Sidi Haj Youssef, localised near the volcano of Ras Tarf, has approximately 100 m thickness of clayey-marly series in which 12 diatomitic levels of variable thickness are intercalated. The microfloristic study of diatoms on 86 samples, carried out in detail for the first time, made it possible to recognize 50 genus of diatoms (24 of centric and 26 of pennate) represented by 185 species (75 species of centric and 110 species of pennate). Four hundred individuals were taken from each sample to determine the relative frequency of each taxon within the diatoms assemblages. Thus, several assemblages were defined by the predominance of the following species: Coscinodiscusmarginatus, Actinoptychussenarius, Thalassionemanitzschioides, Actinocycluscurvatulus, Thalassiothrixlongissima, Rhizosoleniastyliformis and Actinocyclusehrenbergii. These diatoms assemblages display a littoral marine environment in communication with the opened sea. The abundance of the cold water species towards the base and the top of the section suggests broad exchanges of the basin with the Atlantic Ocean in Messinian. The predominance of the species Thalassionemanitzschioides and/or Thalassiothrixlongissima indicates periods of strong productivity that can be associated to upwelling systems.     

La microflore de diatomées au passage mio-pliocène en Corse

The “Aleria formation”, described in northeastern Corsica, consists of siliciclastic deposits referred to a deltaic environment and comprises diatomitic lenses exposed at Casabianda. The Aleria formation fills a depression of the Messinian erosional surface and is overlain by Early Pliocene sediments in several places. This suggests a late Messinian-earliest Pliocene age. Diatom microflora is well-preserved and contains 59 species. Pennates indicate a very large diversity with 54 species, while Centrics are represented only by five species. Diatom assemblages show a relative constant composition along the studied interval. The species Aulacoseiragranulata is the dominant taxon with about 90% in all samples. Taxa are of different salinity classes and different modes of life (planktic, tychoplanktic, benthic, epiphytic…), suggesting multiple environmental factor interactions. The environmental model suggested by sedimentological and biological data led as to assume a pond-like coastal receptacle common in deltaic system. This receptacle was slightly influenced by the close marine waters and was supplied by permanent freshwaters from continental run-off and alluvial sheet. This model based on diatom assemblages provides new data for palaeoenvironmental and chronological interpretations of the so-called Messinian Lago-Mare deposits.     

Les assemblages de diatomées des niveaux infra-gypseux du bassin messinien de Sorbas (Espagne)

In the Sorbas basin, the diatomites represent one of the main sedimentary components of the Messinian together with its two marginal carbonate platforms and the central gypsum deposits. Several vertical sections were taken in the infra-gypsum diatomites from successively more distal paleogeographic areas, ranging from the reef slopes (Cariatiz) to the basin (Los Yesos, Los Molinos). A total of 88 diatom species were determined: 50 centric and 38 pennate. Characteristic assemblages were defined for each category type, revealing ecological variations. In the three sections, plankton forms represent 90 % of the diatoms, with oceanic forms dominating the meroplanktonic and neritic. Nevertheless, some levels clearly indicate a coastal environment, attesting to the carbonate platform influence which progrades toward the basin. The diatom assemblages are relatively homogeneous throughout the three sections, indicating that, before gypsum deposition, the basin was still substantially open to the ocean, with waters sufficiently warm to allow coral reef development. Nevertheless, the basin might also have experienced episodes of colder Atlantic influences.     

Évolution des environnements littoraux du bassin de Melilla-Nador (Nord-Est Maroc) au Messinien supérieur entre 6,0 et 5,77 Ma

This study of late Messinian deposits (E2 = TCC) from Melilla-Nador carbonate complex (Morocco) allowed us to characterize the environmental evolution between 6.0 and 5.77 Ma, which is a period considered as contemporaneous of the onset and development of the “messinian salinity crisis”. A statistical approach coupled together with classical petrographic study allows us to constrain the sedimentary dynamic of platforms and to propose deposition environment models. The Melilla-Nador platforms E2 deposits show a progressive continuous evolution of littoral environments in two major stages of available space creation and infill. The first stage corresponds to the build up of a reef complex between 6.0 and 5.85 Ma then the second stage, between 5.85 and 5.77 Ma, corresponds to the development of a mixed oolitic shallow ramp during the progressive infill of Melilla-Nador basin. The comparison with the Sorbas basin (Spain) TCC deposits exhibits a very close evolution of late Messinian littoral environments, which could be used as a correlation tool.     

Étude biostratigraphique et paléoenvironnementale des diatomées pyritisées de l'intervalle Paléocène supérieur-Éocène inférieur du sondage de Saint-Josse (France)

This paper presents the results of a biostratigraphic analysis of pyritized diatom assemblages in the Saint-Josse core (CC82) located in the northern part of the Paris basin (coordinates: X =555?000, Y =307?324 and Z =56.9 m). During the Paleocene-Eocene this locality was situated in a small bight of the North Sea Basin. The results are obtained from sediments of the Thanet and Mont-Bernon group equivalents belonging to the Paleocene-Eocene interval. Thirteen samples were studied and eleven contain pyritized diatoms. By epigenesis, the siliceous frustule of the diatom is changed into a pyritized skeleton with all the ornamentation very well preserved such as the velum, the areolae, the labiate processes, etc. Dispersive X-Ray analyses show this complete replacement of silica by pyrite. Another form of pyritization is crystallization of pyrite (in cubes, pyritohedrons, octahedrons, framboids) in internal cavities of the diatoms to produce internal moulds, also called steinkerns, which preserve the external morphology of the diatoms and some details such as the girdle. Despite pyritization, diatoms can often be recognized at the species level; brackish and marine species were observed but no fresh water specimens were encountered. Pyrite is easily altered into iron oxides. In outcrops, pyritized diatoms can be obscured or destroyed by oxidation. We have chosen borehole samples for this study to avoid the affects of weathering. Deposits from the Sorrus Unit (of the Thanet Group) have low abundances of pyritized diatoms (3 to 25 specimens per sample). This unit contains allochtonous diatom assemblages comprising Actinoptychussenarius, Coscinodiscus morsianus var. morsianus, and Coscinodiscus morsianus var. moelleri. Sample 34.31-34.45 from this unit is particularly interesting. It contains three specimens of Paralia siberica var. laevis, which is typical of an estuarine or littoral paleoenvironment, and corresponds to the more continental deposit of the Sorrus Unit. Seven samples, taken in the Argile de Saint-Aubin Unit (from the Mont-Bernon Group), contain more than 200 pyritized diatoms and between 9 to 16 different species per sample. A brackish assemblage (Actinoptychus senarius, Coscinodiscus commutatus and Stellarima microtrias) and a marine assemblage (C. morsianus var. morsianus, Coscinodiscus var. moelleri, Fenestrella antiqua, Odontellaheibergii, Rhizosolenia sp. 1 and Trinacria regina) are observed. The brackish assemblage expands in the upper part of the Saint-Aubin Unit indicating more widespread brackish paleoenvironmental conditions. Pyritized diatoms are important fossil markers in the Paris basin mainly when siliceous fossils (silicoflagellates or radiolarians) and others microfossils (foraminifers and dinoflagellates) are very poor or absent. Two diatom assemblages have been identified in the Saint-Josse borehole. The first assemblage D1, comprising C. morsianus var. moelleri (high occurrence), C. morsianus (a few) and T. regina (rare), is recorded in the Sorrus, La Calotterie, Bois Gorguette, Le Goulet and lower Saint-Aubin Units. The second assemblage D2, characterized by great abundance of F. antiqua and decreasing numbers of C. morsianus species, is found in the upper part of the Saint-Aubin Unit. These diatom assemblages can be correlated with other biozonations established in the North Sea basin and based on nannoplankton and diatoms (King, 1983), diatoms (Mitlehner, 1996) and calcareous nannoplankton (Martini, 1971). F. antiqua and C. morsianus var. moelleri are the more important diatom species encountered. F. antiqua (previously named Coscinodiscus sp. 1, King, 1983) is the fossil marker used by King to define his NSP4 biozone. The base of NSP4 corresponds to the lowest occurrence of F. antiqua and the top is marked by the highest occurrence of this species. The Sorrus, La Calotterie, Bois Gorguette, Le Goulet and Saint-Aubin (“Sparnacian” stage) Units, the last one comprising F. antiqua (increasing to acme), correspond to the NSP4 zone of King (1983). The Mont-Hulin and Château de la Bruyère Units correspond probably to the NSP5 zone of King (1983). F. antiqua and C. morsianus var. moelleri were also used by Mitlehner (1996) to differentiate the NSP4a zone (low abundance of F. antiqua and abundance of C. morsianus var. moelleri) from the NSP4b zone (great abundance and acme of F. antiqua). The abundance of C. morsianus var. moelleri is recorded in the lower part of Saint-Aubin Unit and the abundance of F. antiqua (high peak at 46% in the sample 17.87) is found in the upper part of Saint-Aubin Unit. Therefore, Sorrus, La Calotterie, Bois Gorguette, Le Goulet and the lower part of Saint-Aubin Units are correlated with the NSP4a zone and the upper part of Saint-Aubin Unit with the NSP4b zone. By correlating the calcareous nannoplankton biozonation (NP) of Martini (1971) with the biozonation of King (1983), adapted by Mitlehner (1996), the boundary between the NP9 and NP10 zones could be located in the 18.75-17.87 interval and the NP10-NP11 boundary at the top of Saint-Aubin Unit. Lithostratigraphic correlations between the units of the Saint-Josse borehole (Paris basin) and the formations of the North Sea basin can be established. The great abundance of C. morsianus var. moelleri and the great abundance (including acme) of F. antiqua are respectively recorded in the Sele and Balder Formations. Therefore, the interval Sorrus/lower Saint-Aubin Units is correlated with the Sele Formation and upper part of Saint-Aubin Unit with the Balder Formation.     

Palaeoenvironmental conditions preceding the Messinian Salinity Crisis: A case study from Gavdos Island

The Messinian pre-evaporitic sedimentary succession of Gavdos Island (Metochia section) is a nearly uninterrupted succession of marine sediments, dominated by finely laminated diatomaceous marls, which are cyclically alternating with clayey diatomites and white diatomites. The qualitative and quantitative analysis of the planktonic foraminiferal fauna allowed the recognition of nine bioevents, which have been astronomically dated for the Mediterranean. The base of the diatomitic succession in Gavdos Island is dated at 6.722 Ma and the top at 6.015 Ma. The studied section contains benthic foraminiferal genera characteristic of an outer shelf to slope environment. The qualitative and quantitative analysis of this microfauna revealed three benthic foraminiferal fossil assemblages and the occurrence of allochthonous species transported into the bathyal environment by current activity. The cyclical pattern of the benthic foraminifera assemblages indicates that the studied sediments have been affected by repeated episodes of basin restriction characterized by low diversity benthic foraminifera populations, and a limited planktonic foraminifer association typified by shallow, surface-dwelling forms. This restriction was partly due to Antarctic cooling, which produced palaeo-Mediterranean sea-level oscillations during the Early Messinian, as a prelude to closure of the Atlantic connections. The relative impact of climatic versus tectonic control on sedimentation patterns within this basin is discussed.     

Les kystes de dinoflagellés du Crétacé moyen de la marge atlantique brésilienne, le bassin de Santos

Organic dinoflagellate cysts are studied from the sedimentary sequence of hole 1-SPS-14A, drilled during oil exploration in the Santos Basin, Brazilian continental margin. The Ariri and Florianópolis Formations (Transitional sequence) do not contain any dinocysts. The oldest found dinocysts occur at the base of the Drift sequence in sediments, within platform carbonates of the Guarujá Formation. Continuous sea-level rise throughout the late Albian and Cenomanian submerged the carbonate platform with the terrigenous input of the Itanhaém Formation. The transgressive phase reached its peak during the Cenomanian/Turonian transition. Pelites were deposited during oceanic anoxic event (OAE-2), consisting the lower part of the Itajaí-Açu Formation. Normal oceanic conditions re-established in the late Turonian. The Brazilian dinocyst assemblage has tethyan affinities. Some species (i.e., Dinopterygium cladoides, Litosphaeridium arundum, Odontochitina rhakodes and Systematophora cretacea) suggest a middle Albian age for the carbonate platform of the Guarujá Formation. The lower part of the Guarujá Formation was not dated by other microfossils. An uppermost Albian or lower Cenomanian age is suggested for the base of the Itanhaém Formation on the basis of species Palaeohystrichophora infusorioides and Ovoidinium verrucosum. The Cenomanian-Turonian boundary cannot be characterized by dinocysts. Species Atopodinium iuvene, which is known from Turonian sediments in Europe, was found at the top of the Itajaí-Açu Formation. The observed dinocyst bioevents (i.e., last occurrence) are correlated with known foraminiferal, nannofossil and other palynological bioevents. The diversity of the assemblages remains constant throughout the various palaeoenvironments as these are reflected by the Guarujá and Itajaí-Açu Formations, but relative abundances of taxa are variable. Genera Coronifera, Florentinia, Ovoidinium, Spiniferites and Trichodinium are abundant in the carbonate platform assemblages (Guarujá Formation). Genera Cribroperidinium and Cyclonephelium are abundant in detrital sediments (Itajaí-Açu Formation). Only one species (Subtilisphaera guarujaensis n. sp.) is restricted to the carbonate platform environment.     

Stratigraphie, paléoécologie et foraminifères du paléogène des Alpes Maritimes et des Alpes de Haute-Provence (Sud-Est de la France)

Paleogene sedimentation in the Alpes Maritimes and Alpes de Haute Provence regions is composed of one complete sedimentary sequence. This sequence begins with the continental Formation from Microcodium and continues with the Cerithium layers, the Calcaires Nummulitiques and the Marnes Bleues, which are overlaid by the turbidites of the Grès d’Annot Formation. Sedimentation starts in the Nummulites perforatus zone close to the base of ‘the Truncorotaloides rohri zone (P 14) and ends in the Cassigerinella chipolensis-Pseudohastigerina micra zone (P 18) and the NP21 zone in the upper part of the Grès d’Annot. More biomarkers were used in order to define a more detailed local biozonation (biozones AMP 1 to AMP 7). Four local zones were also defined by the last occurrence of Nummulites millecaput and N. perforatus-N. ptukhiani and then by the first appearance of N. retiatus (AMGF 1-4). The evolution of benthic foraminiferal assemblages shows an increase in bathymetry from the internal platform in the Cerithium layers to the calcareous platform with large foraminifers, then to the external platform and the deep offshore environment of the Marnes Bleues and Grès d’Annot. Low faunal diversity in the Grès d’Annot together with the predominance of agglutinated species indicates a poorly oxygenated, organic rich and turbidite environment. Seven steps (SD 1 to SD 7) in the Eocene marine transgression are shown from East to West by detailed local biozonation and sequence analysis. Grès d’Annot sedimentation is also diachronous, beginning within the Truncorotaloides rohri zone (P 14, AMP 1) in the East and ending within the Pararotalia opima opima zone (P 20, middle Rupelian) in the West (Barrême). Small foraminifer Paleogene fauna from the Alpes Maritimes and Alpes de Haute Provence was studied from 400 samples. It is composed of 378 species. Two new taxa are proposed: Fissurina niceana n. sp. and Globocassidulina alpina n. sp. The species from the Escarène and Gorbio neighborhood described by M. von Hantken (1884) were re-examined.     

Les industries acheuléennes de la France septentrionale

The excavations of several open air sites in Northern France and, especially in the Somme basin, have given numerous data concerning the age and the environment of the human occupations for the period from MIS 12 to MIS 8. The quality of the raw material and the function of the different sites have a great effect on the composition of the lithic assemblages as it has been seen for the different sites located near the confluence of the Somme and Avre (Cagny-la Garenne, Cagny-l’Épinette, Ferme de l’Épinette, Gentelles). The characteristics of the lithic industries of Gouzeaucourt show the complexity of the transition from Lower to Middle Palaeolithic.     

Détermination de la limite Crétacé-Tertiaire en Bulgarie par les foraminifères planctoniques

The stratigraphic review and the dating, by means of planktonic foraminifera (Globotruncanidae, Heterohelicidae, “Globigerinidae”), of the main marine Maastrichtian and Paleocene series deposited, in Bulgaria (Fore-Balkan and Luda Kamcija zone), within three paleogeographic domains (foreland turbiditic trough: Emine Formation; hemipelagic basin: Bjala Formation; external/distal-dominated carbonate platform: Mezdra Formation) allow to propose new correlations between the series of the different domains along the North-Tethyan margin. Several features characterize these series: absence of significant lithologic break between Maastrichtian and Danian deposits when they are represented; very local deposition of the Iridium-bearing dark clays underlining the K/T boundary; ponctual evidence of a gap, variable in duration, below and above this boundary (this gap is probably generated by extensional/compressional “laramian” tectonics); diachronism of the glauconitic condensation levels, more or less linked to hard-grounds, which are all included within Paleocene carbonate deposits, various in age, and are never situated at the K/T boundary.     

La migration de la plate-forme urgonienne entre le Jura plissé et les Chaînes subalpines septentrionales (France, Suisse)

The stratigraphic study of the Urgonian carbonate platform presented here was carried out on a directed transversal NW-SE and passing by Geneva. This transversal extends on 100 km length; it lies between the face of the “folded Jura” (Champagnole, the Jura) and the septentrional subalpine chains (Aravis, Haute-Savoie). Essentially based on the biostratigraphy (ammonites, orbitolinids, echinids) and on sequence stratigraphy, this study illustrates the progradation of the Urgonian platform from the “folded Jura” (top of the Lower Hauterivian) to the Aravais chain (lowermost Barremian).     

Latest Messinian “Lago-Mare” Lymnocardiinae from Italy: Close relations with the Pontian fauna from the Dacic Basin

Rich hypo- to mesohaline molluscan assemblages characterising the latest Messinian “Lago-Mare” biofacies, composed of prosobranch gastropods (Neritidae, Thiaridae, Melanopsidae, Hydrobiidae) and bivalves of the families Cardiidae (subfamily Lymnocardiinae) and Dreissenidae, are widespread in shallow water basins characterized by low salinities within the Mediterranean realm, during the post-evaporitic phase in the time-span 5.5-5.3 Ma. Several genera and species are recorded in the Italian uppermost Messinian sediments. While the gastropods show endemic character being linked to continental water-systems, Lymnocardiinae and Dreissenidae have strong Paratethyan affinity. New records of significant species of Lymnocardiinae from the uppermost Messinian sediments of Tuscany, Marches and Sicily and the systematic review of the old literature data point out close relations of the Italian fauna with that from the Pontian sediments of the Dacic Basin. The palaeobiogeographical data referred to Messinian and Pontian Lymnocardiinae suggest that the Aegean Basin could be an intermediate basin from whence the Pontian Paratethyan-type fauna migrated into the Mediterranean area during the latest Messinian. Since the ecology of Lymnocardiinae is mainly tied to oligo- and mesohaline water, spreading of suitable habitats in depositional systems of marginal settings characterized by increasing freshwater influx after the “salinity crisis” favoured their dispersal into the Mediterranean area from the Paratethys realm.     

Le Paléolithique ancien de l’Europe orientale et du Caucase

Currently, only Tréhougol’naya Cave has reliably dated evidence for human settlement in Eastern Europe and Caucasus, from the beginning through the middle of the Middle Pleistocene. In Eastern Europe, assemblages from Khriatchi and Mikhailovskoé, and possibly Darvagchai I, appear to be the only stratified locations that tentatively can be compared (despite problems with these materials) with Tréhougol’naya. In the eastern limits of Central Europe, layer VI in Korolevo I is the only stratified assemblage that may be compared with Tréhougol’naya. All these Lower Paleolithic occupations yielded the Pre-Mousterian small tool industries with some pebble tools, but without Acheulean bifaces and Levallois technique. These data suggest that Eastern Europe lies outside the distribution range of the Acheulean techno-complex demarcated with the “Movius Line”. In the Southern Caucasus, the Dmanissi hominine and lithic records document the fact that the earliest small-brained humans – probably later H. habilis-rudolfensis or earlier H. ergaster-erectus hominids bearing Pre-Oldowan technology – initially left Africa and appeared in Western Asia as early as 1.8 Ma ago. However, in the Southern Caucasus, the available chronological data indicate that the Acheulean complex has a later temporal appearance here compared to the Upper Acheulean or Acheulo-Yabrudian in Western Asia. Two main Upper Acheulean industrial variants currently can be recognized in the Southern Caucasus. The first, called the Kudarian by the author (from the caves of Kudaro I, Kudaro III, and Azyk), is characterized by lithics made from mostly siliceous rocks, rare Acheulean bifaces, and non-Levallois flaking technique. The second variant is characterized by lithics made from volcanic rocks, numerous Acheulean bifaces, and often more laminar or Levallois debitage. It can be suggested that there are independent origins for these Southern Caucasus Upper Acheulean industrial variants. Possible roots of the Acheulean assemblages of Kudarian variant might be in the local earlier Lower Paleolithic small tool assemblages with some pebble tools but without Acheulean bifaces. The other Caucasus variant of the Upper Acheulean appears to be related to the Levantine Upper Acheulean.     

Paleoenvironmental evolution of the eastern Mediterranean during the Messinian: Constraints from integrated microfossil data of the Pissouri Basin (Cyprus)

Integrated data of calcareous nannofossils, as well as planktonic and benthic foraminifera from the Pissouri Motorway section on Cyprus allow the reconstruction of surface- and bottom-water paleoenvironments of the eastern Mediterranean during the interval preceding the Messinian salinity crisis (MSC). Contrary to deeper-water locations, where benthic foraminifera faunas are suppressed or absent just after the Tortonian–Messinian boundary, sediments deposited at intermediate water depths do contain benthic assemblages. From the earliest Messinian onwards, a development towards increasingly unfavourable paleoenvironments is reflected in the planktonic and benthic microfossil records of the Pissouri section and proceeds with rather discrete time steps that can be correlated to sequences throughout the Mediterranean. Shortly after the Tortonian–Messinian boundary a transition is recorded in the sedimentology and the open marine, deeper-water taxa disappear from the benthic foraminifera assemblages; subsequently, the diversity of all fauna groups diminishes. The changes recorded at species level in both surface-water and sea-floor dwelling taxa suggest decreasing circulation of the bottom waters, associated with changes in the surface waters, most likely due to increasing stratification. From ∼6.73 Ma onwards, our data indicate a prominent change to more restricted conditions and increasing salinity at the sea floor together with intermittently rising surface water salinity. The dominance of oligotypic and monospecific assemblages and the frequent shifts in assemblage compositions of all microfossil groups indicate severely stressed environments after ∼6.4 Ma, probably related to increased salinity. The major changes in paleoenvironmental conditions, including oxygen deprivation due to stagnation and hypersalinity, can be explained by hydrographical changes in the Mediterranean basin, which are probably caused by tectonic movements in the Rif Corridor acting in concert with astronomical cyclicity. Evaluation of the paleodepth proxies indicates that the depth of the Pissouri Basin remained rather constant at ∼300–500 m, with a minimum of 200 m, until deposition of the “barre jaune”, the transitional interval towards the evaporites and that early shallowing to neritic depths, as was proposed before, is highly unlikely.     

Réévaluation de la présence humaine au Pléistocène inférieur dans le Sud de l'Espagne

The Early Pleistocene locality at Venta Micena (Orce, Guadix-Baza basin, province of Granada, Spain) has provided four fossil remains - skull fragment VM-0, and long bone diaphyses VM-1960, VM-3691, and VM-12000 - which have been tentatively attributed to the hominids. Although several methodologies have been used to ascertain the human affinities of these specimens - including anatomical, morphometric and immunological analyses - the results obtained have not been conclusive, instigating a persistent debate. A taphonomic approach is used here for estimating the probability that a taxon the size of Homo sp. (~ 50 kg) could be represented in the fossil assemblage by four bone fragments and no tooth remain. A least-squares regression analysis between the percentage of teeth and the body mass estimated for each taxon of large mammals (N = 20) predicts a raw abundance of six teeth for Homo sp. in the assemblage. Given that up to the present moment no tooth remains attributable to the hominids has been unearthed during systematic excavations in the Venta Micena quarry, which has provided more than 15,000 fossils of large mammals, this argues strongly against the possibility that the three bone specimens could belong to Homo sp. The phalanx CV-0 from the Early Pleistocene site of Cueva Victoria (Cartagena, Spain) has also been attributed to the genus Homo. The taxonomic assignment of this specimen is biased, however, because it was not compared with Theropithecus oswaldi, the only primate species actually recorded from this karstic locality. A comparative anatomical and morphometric analysis of fossil and modern specimens of Theropithecus suggests that CV-0 can be attributed to T. oswaldi. As a result, Cueva Victoria does not contribute additional information concerning the first human settlements in Europe. By these reasons, apart from the paleoanthropological and archaeological findings from Atapuerca (TD lower levels and Sima del Elefante), the rich archaeological assemblages from Barranco León and Fuente Nueva-3 in Orce, dated 1.3-1.2 Myrs, which include fourteen hundred stone tools of Oldowan technology, constitute at present the only unequivocal evidence of human presence in Southeast Spain during Early Pleistocene times.     

Le bassin permien de Guardia Pisano (Sud-Ouest de la Sardaigne, Italie) : palynostratigraphie, paléophytogéographie, corrélations et âge radiométrique des produits volcaniques associés

The Permian section outcropping at Guardia Pisano (Sulcis area, SW Sardinia), comprises two successions, separated by an unconformity. The lower succession is composed of grey-black sandy shales, rich in plant remains and in sporomorphs, deposited in a fluvial-lacustrine to palustrine environment; followed by layers of rhyolithic lavas and volcanoclastites with silicified plant trunks. Most of the analysed samples yielded a profusion of pollen and spores in a very good state of preservation. Three associations were distinguished. The first one comprises mostly radial and bilateral monosaccate pollen grains and very few spores. This association is characterized by the presence of pollen grains of the genera Crucisaccites, Luberisaccites, Gondwanopollis and Lueckisporites, together with very abundant Potonieisporites and subordinate Florinites. The second association comprises mostly pollen grains of the genus Potonieisporites, represented by many species, together with Limitisporites, Costapollenites, Vittatina and others. Spores mainly represented by azonate trilete and monolete types are more frequent than in the previous association. These first two palynological associations reflect assemblages of meso-xerophilous plants growing in dryer environments, belonging to tropical and subtropical phytogeographic biomas. The third association, mainly composed of Sphenophyte spores, is autochthonous and corresponds to a swampy hygrophilous flora settled after the filling up of the basin. The age inferred by means of sporomorphs is early Asselian which is in good agreement with the mean radiometric age of the volcanic rocks obtained by the ‘SHRIMP’ and the lead-zircon evaporation methods (297 ± 5 Ma). The upper succession, is composed of grey to red sandstones and thin pelites deposited on an alluvial plain under very hot and humid climate; its Permian, post-Asselian age cannot be better constrained because of the scarcity of the fossil content.     

Évolution des caractères technologiques et typologiques des industries lithiques dans la stratigraphie de la Caune de l'Arago

The thick Quaternary deposits of the Caune de l’Arago (Pyrénées-Orientales, France) are dated to between 690 000 and 90 000 years old. At least fifteen different archeostratigraphical units have been identified within these deposits, each corresponding to distinct prehistoric occupations. Numerous stone tools made from several different rock types, have been discovered in each unit. The tools present specific characteristics concerning the choice of raw materials, the typology, and the technology used to produce them. Morpho-technological study of the different components of the assemblage contributes to a better understanding of the debitage methods used for their production. Each raw material is considered individually in order to ascertain its origin in the environment, its typological role and the technology applied during its exploitation. Defining production systems leads to the characterisation of the assemblages from each unit. When compared, they reveal common elements, as well as differences, suggesting evolutionary trends. Some observations are also made concerning the extent to which changing uses of the site may have influenced the general morphology of each assemblage, therefore taking into account exterior factors. Analysis of this rich stone tool assemblage helps to situate the Caune de l’Arago industry within the larger evolutionary context of the Lower Paleolithic in Mediterranean Europe.     

Comportements de subsistance au Paléolithique supérieur en Crimée : analyse archéozoologique des couches 6-2, 6-1 et 5-2 de Buran-Kaya III

The rockshelter of Buran-Kaya III (Crimea), found in 1990 by A. Yanevich, presents an exceptional stratigraphic sequence ranging from the Middle Palaeolithic to the Neolithic. The cultural layers yielded abundant assemblages of lithic and bone industries, personal adornments and mobiliary art, several ones made of mammoth ivory. We present here the results of zooarchaeological analyses of the large mammal remains from layers 6-2, 6-1 and 5-2, attributed to Gravettian sensu lato, and their interpretation in terms of subsistence behaviours, by comparing the three assemblages. The faunal composition of the three layers is rather homogeneous. The site settlements seem mainly related to the acquisition and treatment activities of small and middle-sized mammals, especially saiga antelope in summer, and large-sized mammals, in winter in 6-1 and maybe also in 5-2. During Gravettian, Buran-Kaya III was repeatedly used as a butchery or short-termed camp-site, probably in summer for hunts of saiga antelope.     

The influence of substrates and physicochemical factors on the composition of diatom assemblages in karst springs and their applicability in water-quality assessment

The methodological standards of monitoring programs recommend collecting material from stones, but this community is often absent in slow-flowing waters, whereas a great number of localities do offer bryophytic material for sampling. In order to investigate whether the kind of substrate (epilithic or bryophytic) influences the diatom-based biomonitoring results the structure of diatom assemblages from 13 anthropogenically altered springs were investigated. To examine differences between diatom assemblages, the species richness of diatom assemblages, H′ (Shannon-Wiener diversity index), Trophic Diatom Index (TDI) and Specific Pollution sensitivity Index (SPI) were compared. The TDI and SPI differed significantly (P = 0.002 and P = 0.004) between springs located in villages and springs away from villages, and did not differ significantly between epilithic and bryophytic samples (P > 0.05). No significant differences in species richness or the diversity index (H′) (P > 0.05) were found between the epilithic and bryophytic diatom assemblages. This study suggests that both the kinds of substrates can be successfully used for diatom-based water-quality biomonitoring in mesotrophic and eutrophic environments.     

PERIPHYTIC DIATOM ASSEMBLAGES FROM ULTRA‐OLIGOTROPHIC AND UV TRANSPARENT LAKES AND PONDS ON VICTORIA ISLAND AND COMPARISONS WITH OTHER DIATOM SURVEYS IN THE CANADIAN ARCTIC1

Periphytic diatoms are potentially powerful indicators of environmental change in climatically‐sensitive high latitude regions. However, only a few studies have examined their taxonomic and ecological characteristics. We identified and enumerated diatom assemblages from sediment, rock, and moss habitats in 34 ultra‐oligotrophic and highly transparent lakes and ponds on Victoria Island, Arctic Canada. The similar limnological characteristics of the sites allowed us to examine the influence of habitat, independent of water chemistry, on the diatom assemblages. As is typical in shallow arctic water bodies, benthic taxa, including species of Achnanthes, Caloneis, Cymbella, Navicula, and Nitzschia, were most widely represented. Minor gradients in our measured environmental variables did not significantly explain any variance in diatom species, but there were marked differences in diatom assemblages among sites. Pond ephemerality seems to explain some diatom variation, because aerophilic taxa such as Achnanthes kryophila Petersen and A. marginulata Grunow were dominant in shallow sites that had undergone appreciable reductions in volume. We identified several taxa that exhibited strong habitat preferences to sediment, moss, or rock substrates and also found significant differences (P < 0.01) in diatom composition among the three habitats. In comparisons with three similar diatom surveys extending over 1200 km of latitude, we determined that surface sediment assemblages differed significantly (P < 0.001) among all regions examined. Diatom species diversity was inversely related to latitude, a result likely explained by differences in the lengths of growing seasons. These data contribute important ecological information on diatom assemblages in arctic regions and will aid in the interpretation of environmental changes in biomonitoring and paleolimnological studies.