Heterosteginapapyracea Seguenza du Miocène du Corridor Sud-Rifain (Maroc) : biométrie et particularités paléoécologiques

Biometric study of the inner features of Heterostegina specimens preserved in tortonian sediments of the oued Yhoudi member allows to confirm the presence of species Heterostegina papyracea Seguenza, 1880. Analysis of both large and small components of the foraminiferal assemblage in all examined samples establishes the dominant character of species Heterostegina papyracea Seguenza (more than 60% of total benthic foraminifera). The assemblage of small benthic foraminifera associated with the Heterostegina is different from that described from Recent sediments, as well as from Miocene sediments of Calabria and Spain. In order to explain this result, two hypotheses can be put forward: (1) the Tortonian Heterostegina from Morocco proliferated abundantly in very shallow environments in association with small foraminifera (i.e. abundant Ammonia beccarii). (2) Because of powerful tidal currents in the South Rifian Corridor, Heterostegina tests were probably transferred after death. This transfer could possibly be due to the narrowness of the South Rifian Corridor in the Early Late Tortonian and its position between the Atlantic and the Mediterranean. Similar cases foraminiferal displacements are also known from modern basins. This study illustrates the difficulties in reconstructing the paleogeography of the studied area and the importance of considering all available components of the assemblage.     

Présence de l’éocrinoïde Ascocystites Barrande (Echinodermata,Blastozoa) dans l’Ordovicien supérieur (Caradoc) de l’Anti-Atlas (Maroc) : premières données

Family Ascocystitidae, defined and established by Georges Ubaghs in 1967, includes a single genus, Ascocystites. This genus was described and figured for the first time by Barrande in 1887, from Bohemian specimens. Thereafter, specimens brought close to Ascocystites or assigned to this genus were described starting from samples collected in Bohemia in the Armorican Massif or in Portugal. The new specimens were collected in Morocco in the Eastern Anti-Atlas, within the formation of Izzeguirene of Caradoc age. The studied material includes several sandy slabes often containing many well-preserved and almost complete individuals. These levels gather individuals of various sizes, corresponding to various stages of development. The morphological study in progress should allow a specific attribution by comparison with the Bohemian and Armorican forms actually known. The Moroccan material has, in addition, the advantage of corresponding to associations of several Echinodermata groups, rich in individuals, allowing a taphonomic and possibly paleoenvironmental study. Biostratigraphically, Ascocystitidae are actually known between Middle (Armorican Massif and Portugal) and Upper Ordovician (Bohemia and now Morocco). The discovery of Ascocystitidae in the Moroccan Anti-Atlas extends their distribution, within gondwanian domain, during Middle and Upper Ordovician.     

Données paléoenvironnementales sur le Vraconnien/Cénomanien de la région de Tébessa (Atlas Saharien,nord-est Algérie). Caractérisation de l’OAE2

The micropalaeontological content of five sections, located in Northeastern Algeria (Saharan Atlas) was investigated by means of washing/counting of microfossils in marly levels, and microfacies analyses of calcareous levels. In these levels of Upper Cretaceous age, hundred species of foraminifera were identified but only about 15 species of ostracoda and about ten of radiolaria. This work allows, first of all, to establish a rather precise stratigraphic frame, in particular by means of studying planktonic foraminifera. Two to five biozones were defined, between the Vraconnian (Th. Appenninica biozone) and the early Turonian (Whiteinella archaeocretacea biozone, then Helvetoglobotruncana Helvetica biozone for certain sections). Secondly, the quantitative analyses led on foraminifera allowed the definition of palaeoenvironment. The ratio P/P+B, generally very high, coupled with a little diversified benthonic microfauna, indicates a calm and deep environment, of external platform or slope type. Furthermore, at numerous levels, various indications give evidence of the existence of a strong surface productivity (presence of upwellings), responsible for the proliferation of radiolaria (late Vraconnian/early Cenomanian especially) or of globular planktonic foraminifera (hedbergellids/heterohelicids); being both associated with low-oxygen deep waters. Two anoxic events were also revealed, the first one at the end of Vraconnian (OAE1d) and the second at the end of Cenomanian (OAE2). This last event in particular was characterized on all the sections, in a more or less detailed way, thanks to the identification of certain indicator: Heterohelix “bloom”, “filament” event, disappearance of rotaliporids, presence of “blackshales” strongly enriched in organic matter (Bahloul levels).     

Les foraminifères du Burdigalien moyen à supérieur de la région sud-aquitaine (golfe de Saubrigues, SW France)

Many exposures assigned to the Miocene formation of “Marnes de Saubrigues” (southwestern Aquitaine Basin) have been studied. Their revised stratigraphical allocation has made it possible to recognize mainly Middle to Late Burdigalian age deposits which have been widely sampled. They have been correlated with planktonic zones N6 pars-N7 and NN3-NN4 and locally dated 17.7 Ma with Sr isotopes. It is noteworthy that this chronological interval is only known in the southern Basin. An inventory of the rather abundant microplankton is provided, including series crossed by drillings in the Gulf of Biscay. These deposits yield a large diversity of benthic foraminifera, nearly 400 taxa, which can be considered as a reference fauna for western Europe Burdigalian. From a geographic point of view, it has been possible to subdivise the exposures into groups according to their bathymetry. Let us point out the first discovery of Borelis in the Burdigalian of France and in the northeastern Atlantic Miocene as well. Very rare specimens of Cycloclypeus are also present in the Aquitaine Basin. Among smaller foraminifera, the occurrence of Rosalina aguayoi, Pavonitina styriaca, the last appearance of Falsocibicides aquitanicus and the persistance of the genus Almaena must be emphasized. Several assemblages supply diatoms, rare radiolaria and sometimes abundant sponge spicules; the presence of these organisms, seldom reported from the Aquitaine Tertiary, might be linked to upwelling-type currents. Bachmayerella (inc. sed.) is uncommon and cited for the first time in the Burdigalian. A few taxonomical remarks and short notes are given for some species of foraminifera, and palaeoecological details as well. Numerous taxa are represented and comparisons with the foraminifera faunas mainly from the Lower-Middle Miocene of Western Mediterranean and Paratethys are sketched.     

Sur l'origine du genre Microceratina Swanson, 1980 (Ostracoda, Eucytherurinae) et sa présence téthysienne dès le Jurassique supérieur

The discovery in the uppermost Jurassic of Lebanon of a species of the ostracod genus Microceratina Swanson, 1980 (Eucytherurinae), of which the oldest known species was until now of Maastrichtian age, confirms the Tethyan origin of this genus. Two new species are created: Microceratina bhannesensis nov. sp. from the Upper Jurassic (Kimmeridgian) of Lebanon, and Microceratina azazoulensis nov. sp. from the Cenomanian of Morocco. The genera Chapmanicytherura Weaver, 1982 and Erratacytheridea Herrig et al., 1997, are considered as probable junior synonyms of Microceratina. An exhaustive bibliographical analysis allowed to identifying several other Cretaceous species susceptible to be assigned to the genus Microceratina.     

Histoire plio-pléistocène des écosystèmes végétaux de Méditerranée sud-occidentale : apport de l’analyse pollinique de deux sondages en mer d’Alboran

The pollen analysis of sediments of two boreholes located in the northeastern Morocco (Nador 1) and in the southeastern Spain (Andalucia G1) has allowed shedding a new light on the vegetation and climate of the North African littoral plains, the Rif Massif and the Betic Range during the Pliocene. The vegetation around the Alboran Sea was open and xeric during the Zanclean, dominated by herbs including subdesertic elements as Calligonum, Lygeum, Nitraria and Neurada. This type of vegetation indicates a dry and hot climate. The southwestern Mediterranean steppes have therefore a climatic character; they existed before the presence and the heavy pressure of Man on the environment. From the Piacenzian, the development, at Andalucia as well as at Nador, of Artemisia and the appearance of some altitude trees such as Cedrus and Cathaya indicate a vegetation change linked to a climatic change. Modifications in the vegetation observed during the same period in northwestern Mediterranean seem to indicate that the vegetation changes observed at Andalucia and Nador are controlled by the appearance of the first arctic glacial-interglacial cycles. The cedar tree appears at Nador only at the end of the Piacenzian, at time of the first cooling, while it has been found punctually in Messinian and early Pliocene sediments of Habibas in Algeria and in Messinian sediments of the Bou Regreg section at Salé in Morocco. The regular presence of Cedar at Bou Regreg during the Messinian, allows supposing that it was present in the Middle Atlas Mountains and that its development was favoured by colder conditions.     

Distribution of ostracod and benthic foraminiferal assemblages during the last 550 kyr in the East-Corsica basin,western Mediterranean Sea: A paleo-environmental reconstruction

The study of Quaternary sediments covering the last 550 kyr from the borehole GDEC-4-2, East-Corsica basin, was performed through the study of benthic meiofaunal assemblages (ostracoda and benthic foraminifera) whose distribution responds to climate changes, and glacial–interglacial variability in particular. The interglacial ostracod group is mainly composed of the Argilloecia acuminata, Cytheropteron alatum, Henryhowella sp., Polycope sp. and Cytherella sp., which indicate an enhanced surface productivity and possibly high bottom water temperature during these warm intervals. Benthic foraminifera, such as Hoeglundina elegans, Sigmoilopsis schlumbergeri, Bigenerina nodosaria and Hyalinea balthica are predominant during interglacial periods and also show an increasing surface productivity associated to warm intervals. Increase in surface productivity would contribute to an enhanced export of organic matter to sea floor at the GDEC-4-2 site during interglacial periods. The bottom temperature drop coupled with the important sedimentary inputs (associated to a significant quantity of refractory organic matter) during glacial periods was highlighted by the predominance of ostracoda, such as Paradoxostoma sp., Cytheropteron testudo, Bathycythere vanstraateni, Macrocypris sp., Echinocythereis echinata and benthic foraminifera as Bolivina spathulata, Bulimina costata, and Bulimina marginata. The distribution of some benthic foraminifera species describing a turnover system allowed the characterization of the last three climate cycles (MIS 8–9, MIS 6–7, MIS 1–5) probably marked by changes of bottom water paleoceanographic conditions in terms of temperature, salinity, bottom current intensity and surface productivity. The cyclic variations of the allochthonous group recorded over the last 550 kyr suggest a major role played by the eustatic factor, with the latter possibly favouring down slope transport. The distribution of this group allowed thus establishing a link between shelf-basin sediment transfer and climate, with enhanced shelf-basin sediment transfer during glacial low stands.     

Variabilité et homogénéité des modes de débitage en Chine entre 300 000 et 50 000 ans

The position of lithic industries of Chinese Paleolithic in comparison with those of other regions in the world is always a controversial topic. The typological analysis has made Chinese prehistorians reveal some variability between lithic industries of different regions of China in terms of technical tradition and industrial structure. But this recognition, based upon some morphological characters of stone artifacts, failed to define systematically the modes of production that exist in each site. To answer these problematic some new methods need to be applied. So the lithic materials from 8 Chinese sites dated from 300 ka to 50 ka B.P. were selected and analyzed by means of lithic technological analysis and a new approach for analyzing the structures of cores. This paper presents principally the analytical results of modes of débitage and revealed that the modes of débitage during this period were characterized essentially by system C (“simple débitage”) and E (discoid) and that the concept Levallois was absent during this period in technical systems of lithic production in China. The Chinese lithic industries between 300 ka and 50 ka B.P. saw some homogeneity in the scale of the continent and remarkable difference from those of other regions in the world. So a stable, continuous but independent even isolated evolution in comparison with those of other regions was observed in this period. In addition, despite of apparent homogeneity, some variability exists also between these industries.     

Corrélation des successions de l'Albien par les ammonites entre la Province Nord-Pacifique et les Provinces européenne et arctique du Domaine boréal : zonation, eustatisme et paléobiogéographie

The vertical distribution of Albian ammonites of the North Pacific Province is described on the basis of several sections located in Northern California. Nine Albian ammonite assemblages are identified, compared to the 4 previously described by Murphy in 1956. Owing to several gaps of observation possibly more assemblages could exist. In the North California Albian history, the first results show a succession of confinement periods - with numerous endemic faunas - followed by periods of open communications with other faunal provinces. As an example, the base of the Middle Albian is marked by exotic ammonites coming from the Tethyan realm (Oxytropidoceras, Lyelliceras) and from the Arctic Province of the Boreal realm (Gastroplites, Pseudopulchellia). These ammonites - except Oxytropidoceras - were not known in that area and are described relatively to their palaeobiogeographical interest. Although rare these migrant faunas give valuable elements to correlate these various provinces. Planktonic foraminifera confirm the existence of open sea communications during the uppermost Albian.With such faunal links, a comparison is proposed between the Albian ammonite zonation of Northern California and the standard and phyletic ones of Europe. This attempt suggests that the major connections between the three faunal provinces are established at second order peak transgressions in the Early and Middle Albian, and during the sea-level high of the Late Albian transgressive period. So, it seems that the vertical distribution of Albian non-endemic ammonites of North California and Europe is largely controlled by global eustatic events. Two palaeobiogeographic maps for Early and Middle Albian and one map for the late Late Albian show the migration outer of these exotic ammonites.     

Des Miliolacea aux Alveolinacea (grands foraminifères): la faune du Crétacé supérieur et du Tertiaire inférieur du Chiapas (S.E. Mexique)

Found in Chiapas (South-East of Mexico), Praealveolina michaudi nov. sp. and Chubbina jamaicensis (of Campanian-Maestrichtian age) are described, both evolved from Nummoloculina sp. while Raadshoovenia guatemalensis (upper Paleocene-lower Eocene) arises from Quinqueloculina. We precisely analyze and modelize the nepionic coiling during the evolutionary change from Miliolacea to Alveolinacea. During ontogenesis as well as during phylogenesis, quinqueloculine coiling progresses to streptospiral and then to planispiral chamber arrangement with the increase of volume of embryo and of chambers. Appearance of these large foraminifers are understood as a consequence of the rise of K-strategies in their mode of life, following the development of photosynthetic symbioses.     

Échinodermes de l'Ordovicien supérieur (Ashgill) de Sardaigne et d'Algérie

Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.     

Découverte de Thyrsoporella pseudoperplexa Granier et Braik, 2002 (algue dasycladale) dans le Kimméridgien inférieur du bassin d'Essaouira (marge atlantique marocaine)

A dasycladacean alga recently attributed to the species Thyrsoporella pseudoperplexa Granier and Braik 2002, has been discovered within the Jurassic sediments of the Atlantic domain. This alga, only found in the Tethysian domain, was identified in the Early Kimmeridgian sediments of the Essaouira basin (Morocco).     

Enregistrement des fluctuations du niveau marin dans l’Holocène supérieur du lac Retba (Sénégal) par les foraminifères

A study of sea level fluctuation records based on foraminiferal assemblages was carried out for the first time in a sediment core taken at the Lac Retba edge. A total of 37 foraminifera species were collected along the core, among which most are known in the modern estuaries and lagoons of Senegal. A succession of four assemblages dominated by Ammonia parkinsoniana and A. tepida were identified; they correspond to different stages of evolution of the lake. The first association, at the base of the core, indicates a lagoon slightly opened to the sea and bordered with vegetation, under relatively humid climate. The second has the richest and most diversified microfauna with a high proportion of coastal, marine benthic and planktonic species (about 10%) that indicate a small coastal gulf bordered with mangroves. The third association is oligospecific and typical of a closed and hypersaline lagoon under a dry climate. The last association again contains coastal, marine benthic and scarce planktonic species (3%) indicating a change to a saltier and more open lagoon under dry climate. The disappearance of planktonic foraminifera at the top of the core indicates the closure of the lagoon. The biocenotic indicators are evidence for two marine intrusions that are referred to the Dakarian (3000 years B.P.) and Saint-Louisian (2140-680 years B.P.) stages of the Upper Holocene of the senegalo-mauritanian stratigraphic scale. Evidence of the Lac Retba closure since 680 years B. P. appears in the core by high reduction of foraminifers’ abundance and diversity absence of planktonic species, and salts precipitated at the bottom of the lake.     

Carboniferous aulate corals from Azrou-Khenifra Basin (Morocco): Distribution and phylogenetic relationships

The Carboniferous outcrops from the Azrou-Khenifra Basin (central Morocco) have yielded solitary and fasciculate aulate corals. Although mostly rare, their presence has significance for extending the known stratigraphic range of two genera. Both Solenodendron and Semenoffia which were previously restricted to the Tournaisian-Viséan interval are now recognised to range up into the Serpukhovian. Moreover, Solenodendron is now last recorded in lower Bashkirian strata, having survived the end-Serpukhovian (mid-Carboniferous) faunal crisis. New phylogenetic relationships are proposed within this aulate group of corals for the western Palaeotethys, based on detailed examination of their morphology, microstructure and stratigraphic range. The distribution of solitary and fasciculate aulate corals in the Azrou-Khenifra Basin (Morocco) is comparable with that of the Béchar Basin (Algeria), and some species are commonly recorded in Europe. A new species, Aulokoninckophyllum potyi is described.     

La macrofaune du Pléistocène supérieur d’El Harhoura 2 (Témara, Maroc) : données préliminaires

The El Harhoura 2 cave is situated in the commune of El Harhoura in the Temara region (Morocco). The entrance faces west, towards the ocean, around 200 m away from the current shoreline and about 16 m above sea level. The stratigraphy has currently 11 levels numbered from top to bottom. Level 1 is attributed to the early Neolithic. The archaeological material from level 2 places it within the Upper Palaeolithic (Iberomaurusian). Levels 3 to 11 are assigned to the Middle Palaeolithic (Aterian). Since 1977, a surface of 37 m² has been excavated, yielding particularly abundant remains of a large mammal fauna study in this paper.     

Succession des peuplements d’échinides du Crétacé inférieur dans le Haut Atlas atlantique (Maroc) ; révision systématique et intérêt stratigraphique

The rich echinoid fauna from the Lower Cretaceous of the Agadir, Haha and Essaouira basins has been revised taxonomically, based on new and abundant collections. Forty-seven species have been identified, of which 20 are reported for the first time from this region and a further three represent new species left in open nomenclature. Their stratigraphic ranges have been determined accurately by reference to the regional ammonite zonation. However, it is also possible to use a local biostratigraphical scheme based on the echinoid succession, where ammonites are rare. The Toxasteridae, which are very abundant and underwent rapid evolution, are the most useful biostratigraphically. The genus Toxaster appears in the Lower Berriasian and continues until the Gargasian passing through the following succession: T. africanus, T. granosus, T. kiliani, T. lorioli, T. obtusus, T. exilis, T. retusus, T. maurus, T. peroni, T. collegnoi. The presence of Eoholaster, Macraster, Douvillaster, Palhemiaster, Heteraster and Pygopyrina is signaled for the first time in the Atlantic High Atlas region.     

Découverte de charophytes de l’Albien dans la Formation Kebar (Tunisie centrale) : implications paléoécologiques et paléobiogéographiques

In Tunisia, in the platform domain, the Aptian-Albian transition is associated with a major stratigraphic gap not precisely dated, which is related to the subaerial exposure of the Aptian Orbata platform. Locally, in central Tunisia (Jebel Kebar), this gap is substituted by the sedimentary records of the Kebar Formation. This formation provided a rich association of fossil charophytes, formed by Atopochara trivolvis trivolvis, Clavator harrisii zavialensis and Sphaerochara verticillata which allows attributing it to the late Aptian–early Albian interval (most probably early Albian). In addition, a new variety, Sphaerochara verticillata var. kebariensis, is described. The charophyte assemblage shows significant biogeographic affinities with a coeval flora found in the Iberian Peninsula. The Kebar Formation was previously regarded as exclusively nonmarine, but the presence of the assemblage of charophytes and associated ostracods described rather indicates a fluctuation between margino-littoral (lagoonal) and continental environments.     

Les faunes d’ammonites du Pliensbachien inférieur des séries dauphinoises de la Durance (Jurassique inférieur, Barrage de Serre-Ponçon, Hautes-Alpes, France)

The Liassic ammonite faunas and especially those of the Early Pliensbachian are of major importance for the understanding of the stratigraphic framework of the “Dauphiné” zone of the southern subalpine ranges (“dôme de Remollon”). Until now, only listed by the authors, these faunas are, for the first time, described and illustrated in the present paper. With about twenty species, these faunas cover the whole of the Early Pliensbachian. There are poorly diversified and of clearly Euroboreal affinities. Nearly all of the species are abundant and common in most of the NW European fossiliferous localities. Despite of a paleogeographical location fairly close to the Alpine zones (Southern Alps and Austroalpine units) with rather diversified faunas of mainly Mediterranean affinities, none Mediterranean taxa are present in the studied area. Unfortunately, the current stratigraphic and paleogeographic knowledge do not allow to ascertain if this reflects a separation due to paleoenvironmental or true paleogeographic barriers. In this latter case, the general geologic implications would be remarkable.     

Charophytes du Crétacé/Paléocène du Moyen-Atlas (Maroc) : systématique et implications biochronologiques

Gyrogonites of charophytes from two localities of the Oudiksou syncline (Middle Atlas, Morocco) are studied. The Irbzer formation in the Achlouj-2 site yielded charophytes (Feistiella oblonga, F. globosa, Strobilochara apiculata, S. diademata) that suggest a Campanian-Maastrichtian age; this result is consistent with all previously published biochronological studies. The overlying Bekrit-Timahdit formation, supposed to be Thanetian to Lutetian in age, without paleontological evidence, yielded charophytes in the Saf locality (Peckichara cf. llobregatensis, Feistiella sp. 1, Maedleriella sp.). This association indicates a Paleocene age for the middle member of this formation.     

Figurines du Paléolithique supérieur en matière minérale plastique cuite d’Afalou Bou Rhummel (Babors, Algérie). Premières analyses par spectroscopie d’absorption Infrarouge

From 1983 to 1993, S. Hachi’s last excavations at the Afalou Bou Rhummel (Algeria) Babors coastal shelter have contextually produced numerous anthropological and zoological, clay figurines, all hand made and cooked, among Iberomaurusian Late Upper Palaeolithic remains. Regarding Maghrebian territories (Morocco, Algeria, Tunisia and Libya), these so peculiar documents are strictly related to 15?000-11?000 BP levels, although deeper archaeological levels are 18?000 BP. Twenty eight small samples (less 1mg) were analysed through infrared absorption spectroscopy (IR) so as to precise, through typical transformation of the major mineral involved: kaolinite, smectites, and amorphous silicates, the final degree of temperature reached after cooking. These documents were all intentionally cooked between 500 and 800 °C. Local clay was obviously picked up for figurine elaboration.