Search results for "STRATIGRAPHY"
showing 10 items of 904 documents
Dolomitization as an eventualdetermining factor in the colour alteration index (CAI)
1993
Abstract The Colour Alteration Index of conodonts (CAI) is indicative of the degree of alteration of organic material that exists in the interior of the conodonts. This CAI is used ordinarily in the determination of paleotemperatures. More frequent findings of abnormally high CAI values, equivalent to paleotemperatures that are not compatible with temperatures obtained by other more trustworthy methods, has taken us to use values not superior to 6 for the establishment of paleotemperatures. The CAI values measured in specimens proceding from dolostones in the Iberian Range (Spain) show in this way a certain degree of incompatibility with geological data. These anomalous values are the conse…
Does porewater or meltwater control tunnel valley genesis? Case studies from the Hirnantian of Morocco.
2015
18 pages; International audience; Several Ordovician tunnel valleys are exposed in the Moroccan Anti-Atlas Mountains, including the Alnif and the Foum Larjamme tunnel valleys, located 150 km away from each other. Sedimentological and deformational analyses of these two glacial troughs reveal that differing processes lead to their formations.The Alnif tunnel valley contains numerous deformation structures within sediments both below and above the main glacial erosion contact surface. Ball-structures and clastic dykes occur within preglacial sediments down to 35 m below glacial incisions while overlying glacial sediments contain fluted surfaces, clastic dykes, dewatering structures, folds and…
Benthic foraminifera as indicators of relative sea-level fluctuations: Paleoenvironmental and paleoclimatic reconstruction of a Holocene marine succe…
2017
This study presents the results of an integrated stratigraphic analysis conducted on a marine gravity core (MSK-12 C4) recovered from the outer continental shelf (82 mwater depth) of western Calabria, ~2.6 km, NE of Capo Vaticano (Eastern Tyrrhenian margin). The gravity core MSK-12 C4 recovered a stratigraphic succession of 4.18 m beneath the seafloor representing the last ~11.1 ka. Sedimentological analysis, micropaleontological quantitative analysis on benthic foraminiferal assemblages, tephrostratigraphy, sequence stratigraphic analysis of high resolution reflection seismic data recorded in the core site area and AMS 14C absolute age determinations allowed reconstructing the marine recor…
A facies distribution model controlled by a tectonically inherited sea bottom topography in the carbonate rimmed shelf of the Upper Tithonian–Valangi…
2016
The Upper Tithonian–Valanginian shallow-water carbonates outcropping in the Palermo Mts (NW Sicily) consist of several facies associations reflecting different depositional environments of a carbonate rimmed shelf, pertaining to the Southern Tethyan continental margin. The reconstructed depositional model, based on the sedimentological features, cyclic facies arrangement and biota distribution, shows that a wide protected lagoon, dominated by algae, molluscs and scattered patch reefs, was bordered landward by a tidal flat, where stromatolitic algal mats were cyclically subaerial exposed, and seaward by a marine sand belt and reef complex. Oolitic packstone-grainstone lithofacies, cyclically…
Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation
2014
International audience; This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, ∼ 6 and ∼ 0.2 k BP in Eu-rope. We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthro-pogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land …
Contribution à la compréhension des relations entre calcarénites et calcaires à rudistes du Barrémien inférieur dans le Vercors méridional (sud-est d…
2006
12 pages; Ce travail porte sur les calcaires à rudistes (Monopleuridae et Requienidae du Barrémien inférieur et base du Barrémien supérieur, essentiellement) du Vercors méridional. Il s'intéresse tout particulièrement aux relations qui existent entre ce faciès et les calcarénites barrémiennes de ce secteur. Les coupes levées et les panoramas réalisés montrent que le motif de dépôt des formations concernées est répétitif et indique, pour ce qui concerne les calcarénites, une diminution de l'hydrodynamisme que l'on interprète comme due à une augmentation de l'accommodation. Les calcaires à rudistes sus-jacents, et qui se mettent en place avant des calcaires argileux ou des dépôts marneux, sem…
Vignes et vins de l'Auxois en quête d'histoire
2019
International audience
Horses and Cowboys on the Contemporary American Stage: The Horse as Prop in Sam Shepard’sKicking a Dead Horseand Sarah Ruhl’sLate: a cowboy song
2021
This comparative essay analyses the dramatic representation of horses in two early twenty-first-century American plays by Sam Shepard and Sarah Ruhl. Both plays bring a horse figure onto the stage ...
Spatial models for monitoring the spatio-temporal evolution of ashes after fire-a case study of a burnt grassland in Lithuania
2013
Ash thickness is a key variable in the protection of soil against erosion agents after planned and unplanned fires. Ash thickness measurements were conducted along two transects (flat and sloping areas) following a grided experimental design. In order to interpolate data with accuracy and identify the techniques with the least bias, several interpolation methods were tested in the grided plot. Overall, the fire had a low severity. However, the fire significantly reduced the ground cover, especially on sloping areas, owing to the higher fire severity and/or less biomass previous to the fire. Ash thickness depended on fire severity and was thin where fire severity was higher and thicker in lo…
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…