Search results for "Cretaceous."
showing 10 items of 166 documents
Sedimentary dynamics and extensional structuring related to early Cretaceous rifting of Neocomian and Barremian deposits of the interior basin of Gab…
2008
18 pages; International audience; Recent field and subsurface data about the early Neocomian N'dombo series and the Neocomian to mid-Barremian Schistes series of the interior basin of Gabon further our understanding of the initial stages of early Cretaceous N40–60E extensional rifting. The syn-rift series comprise fluvial–lacustrine claystones–sandstones, rare conglomerates, and carbonates. The syn-rift fill begins with braided-stream feldspathic sandstones. These are overlain first by fluvial–lacustrine deposits and then by predominantly lacustrine–palustrine claystones, which are potential petroleum source rocks. The claystones are eroded in part and are capped by the pre-Aptian angular u…
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…
The Valanginian positive carbon isotope event in Arctic Russia: Evidence from terrestrial and marine isotope records and implications for global carb…
2010
The data presented here comprise Ryazanian–Valanginian carbon isotope ratios analyzed from fossil wood and belemnites from the shallow marine Boyarka River succession in Siberia. Additional belemnite carbon isotope ratios from the Izhma River succession (also Ryazanian–Valanginian) in Russia are also presented. The wood-derived and belemnite-derived isotope ratios are considered to primarily reflect changes in the terrestrial and marine carbon isotope reservoirs respectively. The δ13Ccarb and δ13Cwood records reveal a distinct mid-Valanginian positive carbon isotope excursion, with the initiation occurring near the Boreal Russian michalskii–polyptychus zone boundary, which is broadly time-e…
Evolution of neodymium isotopic signature of seawater during the Late Cretaceous: implications for intermediate and deep circulation.
2016
20 pages; International audience; Neodymium isotopic compositions (εNd) have been largely used for the last fifty years as a tracer of past ocean circulation, and more intensively during the last decade to investigate ocean circulation during the Cretaceous period. Despite a growing set of data, circulation patterns still remain unclear during this period. In particular, the identification of the deep-water masses and their spatial extension within the different oceanic basins are poorly constrained. In this study we present new deep-water εNd data inferred from the Nd isotope composition of fish remains and Fe–Mn oxyhydroxide coatings on foraminifera tests, along with new εNd data of resid…
Revisión de la sección del yacimiento del Mas de la Chimenea Alta (Formación Arcillas de Morella, Castellón) y significado en el contexto paleoambien…
2012
Desde los primeros estudios estratigráficos y paleontológicos, que datan de principios del siglo XX, la Fm Morella se ha caracterizado por su coloración rojiza y su contenido fósil. La mayor parte de sus depósitos se han interpretado como continentales, aunque con intercalaciones locales de materiales marinos. En esta unidad se da la paradoja de que muchos de los lugares descritos con fauna de vertebrados continentales se encuentran en depósitos interpretados como ambientes marinos poco profundos y de transición. La sección del Mas de la Chimenea Alta es un ejemplo. Ésta contiene yacimientos con fósiles de vertebrados que son claramente alóctonos, pero también otros, con icnitas que permite…
Fossil echinoid (Echinoidea, Echinodermata) diversity of the Early Cretaceous (Hauterivian) in the Paris Basin (France).
2013
11 pages; International audience; This dataset inventories occurrence records of fossil echinoid specimens collected in the Calcaires à Spatangues Formation (CSF) that crops out in the southeast of the Paris Basin (France), and is dated from the Acanthodiscus radiatus chronozone (ca. 132 Ma, early Hauterivian, Early Cretaceous). Fossil richness and abundance of the CSF has attracted the attention of palaeontologists since the middle of the nineteenth century. This dataset compiles occurrence data (referenced by locality names and geographic coordinates with decimal numbers) of fossil echinoids both collated from the literature published over a century and a half, and completed by data from …
The significance of dropstones in a tropical lacustrine setting, eastern Cameros Basin (Late Jurassic–Early Cretaceous, Spain)
2004
International audience; Outsized clasts (mainly white quartzite pebbles) are found in carbonate deposits of the Enciso Group exposed on the northern border of the Cameros rift basin (Late Jurassic – Early Cretaceous, northern Spain). In the Arnedillo section, all the stones are enclosed in micrite, which was assumed deposited in littoral to open lacustrine environments, with minor inputs of deltaic sandstones. The clasts are found in fine-grained lacustrine sediments either as isolated stones or as loosely packed elongated clusters occasionally associated with quartz sands and gravels. The mean size of the clasts is 40 mm (range: 3 – 100 mm); they are polished, well-rounded, and lack any fa…
Anza palaeoichnological site, Late Cretaceous, Morocco. Part III: Comparison between traditional and photogrammetric records
2020
11 pages; International audience; The present study evaluates a methodological workflow that could identify dinosaur tracks and trackways more comprehensively at outcrop scale. The approach described here is based both on 3D modelling by photogrammetry at different resolutions, and on suitably processed digital elevation models (DEMs). The ichnosite of Anza, Morocco, was chosen to demonstrate the efficiency of the proposed pipeline, because 323 dinosaur and pterosaur tracks discovered there have already been published. One subsector containing 89 tracks, identified in the two companion works that followed a traditional approach, was selected and divided into four subzones. By combining diff…
Geochimica e petrografica di black shales del Livello Bonarelli, sezione di Novara di Sicilia (Monte Peloritani), Sicilicia nord-orientale: Implicazi…
2000
Black shales ad alto potenziale petrolifero, alternati ritmicamente a marne e argilliti, affiorano in associazione con Argille Varicolori (Cretaceo-Paleogene) nei pressi di Novara di Sicilia (Monti Peloritani, Sicilia nord-orientale) costituendo l’espressione sedimentaria di un evento anossico con diffusione globale (OAE2), riferibile al Cenomaniano superiore. I depositi corrispondenti a tale evento sono individuati come “Livello Bonarelli”. In detta successione, le alternanze black shales-marne-argilliti si estendono per uno spessore di circa 11 metri passando verso il basso ad alternanze irregolari di calcari marnosi, marne chiare, marne scure, argilliti e calcareniti (spessore ca. 9 m) c…
Cenomanian rudist-dominated shelf-margin limestones from the Panormide carbonate platform (Sicily, Italy): facies analysis and sequence stratigraphy
2000
Sedimentological, paleontological and sequence analyses of Cenomanian limestones in Sicily reveal thc facies architecture and dynamics of a Mid Cretaceous rudistdominated platform margin from Western Tethys. The studied deposits outcrop near Palermo, as part of a large structural unit of the Sicilian Maghrebids. They belong to the Panormide carbonate platform, a Mesocenozoic paleogeographic domain of the African margin. The lateral continuity of the beds along three nearly parallel E-W outcrop sections allowed the recording of cm/dm thick lithological and faunal variations. Nine main lithofacies associations have been recognised along about 200 m of subvertical strata. Their vertical and la…