Search results for "stratigraphy"
showing 10 items of 904 documents
Chronology for the Cueva Victoria fossil site (SE Spain): Evidence for Early Pleistocene Afro-Iberian dispersals
2014
Cueva Victoria has provided remains of more than 90 species of fossil vertebrates, including a hominin phalanx, and the only specimens of the African cercopithecid Theropithecus oswaldi in Europe. To constrain the age of the vertebrate remains we used paleomagnetism, vertebrate biostratigraphy and (230)Th/U dating. Normal polarity was identified in the non-fossiliferous lowest and highest stratigraphic units (red clay and capping flowstones) while reverse polarity was found in the intermediate stratigraphic unit (fossiliferous breccia). A lower polarity change occurred during the deposition of the decalcification clay, when the cave was closed and karstification was active. A second polarit…
Impact of sedimentology and diagenesis on the petrophysical properties of a tight oolitic carbonate reservoir. The case of the Oolithe Blanche Format…
2013
18 pages; International audience; The Oolithe Blanche Formation was studied in three quarries, located at the south-eastern edge of the Paris Basin (France). Heterogeneities in reservoir properties were assessed through a sedimentological, diagenetic and petrophysical study. The relationships between depositional settings, diagenesis and petrophysical properties were analysed using detailed petrographic studies, image analysis, Nano CTscans and petrophysical measurements. The carbonate reservoir pore network is mainly controlled by intraparticle microporosity which ensures the connectivity with interparticle meso- and macroporosity. Early cementation vs. early compaction processes (mainly g…
Continental weathering and climatic changes inferred from clay mineralogy and paired carbon isotopes across the early to middle Toarcian in the Paris…
2014
Abstract Lower Toarcian strata (Lower Jurassic) have been extensively studied with a view to understanding the oceanographic, climatic and biological processes that drove the Earth's system into an Oceanic Anoxic Event (OAE). For this time period, the evolution of the European marine seaways is now relatively well constrained owing to multiple geochemical studies, but investigations regarding climatic trends in the continental realm remain sparse. In the present study, we test the clay mineralogy as a continental climate-sensitive proxy in the well-documented Sancerre core (southern Paris Basin). We compare variations in the kaolinite content with p CO 2 fluctuations (derived from paired ca…
Human settlement dynamics and alluvial dynamics of the Rhine River during the Holocene: Geoarchaeology of the site of Oedenburg (Haut-Rhin, France).
2007
The relationship between alluvial dynamics and control parameters such as climate are well known and understood at plurimillennial and pluriannual time-scales. But it is not really the case at multicentennial and multidecennal time-scales compatible with human society settlement time-scales. In a present and near future context, when human settlement may be affected by strong climatic variation, alluvial dynamics understanding is however a major centre of attention to the development of efficient models. To approach this scale-related question, a segment of the Upper Rhine River presenting both anastomosed and braided was investigated. This area also gives us the opportunity to study settle…
Cenomanian–Turonian carbonate and organic-carbon isotope records, biostratigraphy and provenance of a key section in NE Sicily, Italy: Palaeoceanogra…
2008
In eastern Sicily, a series of highly organic-rich black shales occur as exotic blocks (~ 100 m across) floating in tectonized sediments (Argille Varicolori Unit containing olistoliths of Cretaceous-Palaeogene age). A 19-metre section, through one of these blocks near the town of Novara di Sicilia, includes cyclically bedded black shales, marlstones and claystones, which have been dated using planktonic foraminiferal and nannofossil biostratigraphy. On this basis, the section is assigned to the latest Cenomanian and clearly represents a manifestation of the Oceanic Anoxic Event characteristic of that interval. Total organic-carbon values range up to 23% and the relatively high hydrogen indi…
Sediment-associated retene bioavailability of sediment-associated retene to an oligochaete wormlumbriculus variegatus
2001
The bioavailability of retene spiked to two sediment concentrations (50 and 200 µg/g dry weight) was measured in long-term (28-day) bioaccumulation tests performed on the oligochaeteLumbriculus variegatus Muller. Three sediment organic carbon (SOC) concentrations (1.1, 3.0, 23.0% of dry weight) were used. Growth and reproduction, used as endpoints, indicated that retene was chronically nontoxic at the concentrations employed. Retene was clearly bioavailable, but bioaccumulated about 100 times less in the SOC-rich (23.0%) sediment than in the other two (SOC <3.0%). At the lower retene concentration, retene in the worms was undetectable in the high-SOC sediment. Based on final retene present …
Étude de deux formations carbonifères du Morvan méridional dans le cadre de l'orogenèse hercynienne (Région du Creusot, Saône-et-Loire).
2006
18 pages; National audience; Dans la région creusotine, deux formations sédimentaires, l'une d'un âge incertain, Dévonien, Dévono-Dinantien, Dinantien, selon les auteurs, et l'autre du Stéphanien supérieur, ont été étudiées. La première nommée Formation (Fm) des Alouettes, est bordée au nord par le granite d'Uchon responsable d'un métamorphisme de contact. Des filons de microgranite la recoupent. Elle est d'abord constituée par une alternance de grès et de siltites laminées charbonneuses dans lesquelles on rencontre des rides de courant, figures d'érosion ainsi que des racines de Lépidophytes (Stigmaria) et des tiges d'Equisétales (Bornia). Cette partie est recouverte par des conglomérats à…
La transgression cénomanienne et l'âge des "Tourtias" du nord du bassin de Paris (F) et du bassin de Mons (B).
2010
29 pages; National audience
New biostratigraphic data from the Ladinian pelagic limestones of Pizzo di Sant’Otiero - Madonie Mountains, Sicily
2014
New biostratigraphic data, based on conodont investigations, were collected from the Ladinian limestones recently described at Sant’Otiero, a locality near the Village of Petralia Sottana in the Madonie Mountains (Central-Northern Sicily). At this locality a new calcareous succession lying at the base of a major tectonic unit of the Maghrebian chain is described. This succession consists of a lower massive part formed by a carbonate megabreccia, the elements of which are shallow water extraclasts with dasycladalean algae (Diplopora annulatissima Pia), benthic foraminifers, “Tubiphytes” and problematic organisms commonly described from Anisian carbonate platforms. Upward a well-bedded succes…
Biocénoses à triopsidés(Crustacea, Branchiopoda) du Permien du bassin de Lodève (France)
1997
Resume Nous decrivons les triopsides (Crustacea, Branchiopoda) qui abondent dans les facies “saxoniens” de la Formation du Salagou du bassin de Lodeve date “Thuringien” ou “Saxonien” selon les auteurs. A partir de milliers de debris de carapaces, d'axes thoraco-abdominaux et plus rarement a partir d'animaux entiers, nous avons identifie et decrit deux especes nouvelles: Triops cancriformis permiensis nov. ssp. et Lepidurus occitaniacus nov. sp., morphologiquement proches d' especes actuelles. En se basant sur les preferences ecologiques des triopsides actuels et les caracteristiques sedimentologiques de leur milieu de vie au Permien, nous avons confirme l'existence d'etendues d'eau, peu pro…