Thèses sur le sujet « 14C datation »
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Lindroos, Alf. « Carbonate phases in historical lime mortars and pozzolana concrete : implications for 14C dating / ». Åbo : Department of geology and mineralogy, Åbo akademi university, 2005. http://catalogue.bnf.fr/ark:/12148/cb41081971h.
Texte intégralCourel, Blandine. « Caractérisation de substances naturelles en contexte archéologique : apport des études moléculaires, isotopiques et de la datation au 14C ». Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF026/document.
Texte intégralIn this archaeometric study, lipid biomarkers from archaeological soils and organic substances originating from plants found on artefacts were investigated by GC-MS. In addition, the stable carbon isotopic composition of individual lipids and the 14C age (AMS MICADAS) of soil organic matter, lipid extracts and one isolated compound (miliacin) were determined. Such an archaeometric approach allowed:- the existence of a millet cultivation during the Bronze Age in Alsace to be unveiled for the first time based on preserved molecular remains of this cereal in agricultural soils trapped within grain silos dated from the Iron Age.- the function of uncharacterized archaeological structures to be identified as ancient latrines and a stall area based on the identification of faecal steroidal markers.- reliable chemotaxonomic criteria for the authentication of styrax resins and liquidambar gums to be established using specific organic markers (triterpenoids, notably).- the vegetal component of an organic coating decorating a skull from the 9th millennium BC (Nahal Hemar site, Israel) to be identified as a resin from Styrax officinalis.- the use of birch bark tar as adhesive for the making of a jewellery dated from the Iron Age to be discovered
Montjotin, Corinne. « Isolation, caractérisation et mesure des teneurs en 14C de substances humiques aquatiques : application à la datation des eaux souterraines ». Paris 11, 1996. http://www.theses.fr/1996PA112438.
Texte intégralSuharta, Nata. « Etude biodynamique de trois humus forestiers modèles de l'Est de la France : caractérisation fine des matières organiques par fractionnement granulométrique, datation 14C et observations ultrastructurales ». Nancy 1, 1992. http://docnum.univ-lorraine.fr/public/SCD_T_1992_0134_SUHARTA.pdf.
Texte intégralRanchoux, Coralie. « Caractérisation géochimique et datation des circulations d'eaux profondes dans la zone critique : cas du bassin versant du Strengbach ». Thesis, Strasbourg, 2020. http://www.theses.fr/2020STRAH010.
Texte intégralThe PhD thesis concerns the geochemical characterization and the determination of the residence times of the water circulating in the deep part of the substratum of the Strengbach catchment. The work is based on the comparative study of chemical, isotopic variations (87Sr/86Sr, 143Nd/144Nd and (234U/238U)) and water geochronometers (CFC-SF6, 14C, 4He) of samples from spring, piezometers (15 m deep) and deep boreholes.The results highlight two types of water, with lower cationic loads for surface waters (spring and piezometer water) than deep water, sampled in front of the main fractures. The origin of these differences has been discussed in terms of variation in residence times and from a point of view of water-rock interactions. This study has shown that an important factor explaining these differences is the residence time of waters, with recent waters in the surface system and old waters (more than 1000 years) in the deep system. The isotopic analysis has shown that the Sr-Nd signatures of the different water can, at first order, be explained by the dissolution of the phosphate-plagioclase-biotite end-members conventionally used on the catchment. The variation between the different deep waters suggests interactions with specific secondary minerals for each of the waters
Sepulcre, Sophie. « Essais de datation absolue et reconstitutions paléoclimatiques en Mer des Caraïbes : approche multi-traceurs sur les foraminifères planctoniques et la fraction fine aragonitique ». Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2008. http://tel.archives-ouvertes.fr/tel-00323031.
Texte intégralsynchronisme entre le δ18O et les âges absolus de deux fractions de tailles différentes et 2) reconstruire les paléoenvironnements de la zone. La minéralogie de la fraction fine est contrôlée par les changements du niveau marin à l'échelle glaciaire-interglaciaire. Les décalages temporels entre le δ18O et le 14C des deux fractions durant la Terminaison I sont en partie expliqués par un modèle de bioturbation. Les essais de datation U/Th sur la fraction fine des Terminaisons II et V ont montré une contamination par du Th non-radiogénique, nécessitant des développements analytiques. Les reconstitutions des variations de δ18O de l'eau de mer suggèrent une diminution de la salinité de surface à la fin de la Transition Mid-Pléistocène, associée à la position de l'ITCZ au niveau de la Mer des Caraïbes.
Jacks, Xavier. « Méthodes de datation des objets anciens ». Paris 5, 1994. http://www.theses.fr/1994PA05P089.
Texte intégralEvin, Jacques. « Fiabilité des matériaux utilisés en datation par le radiocarbone ». Lyon 1, 1991. http://www.theses.fr/1991LYO10175.
Texte intégralGabasio, Martine. « Application de la datation radiocarbone à des céramiques archéologiques grises ou noires ». Lyon 1, 1987. https://tel.archives-ouvertes.fr/tel-02091580.
Texte intégralDelque-Kolic, Emmanuelle. « Méthodes d'extraction du carbone des poteries pour leur datation par le radiocarbone ». Lyon 1, 1995. http://www.theses.fr/1995LYO10119.
Texte intégralMessager, Cyrielle. « Datation par la méthode du radiocarbone de pigments et peintures anciennes à base de blanc de plomb ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASJ005.
Texte intégralRadiocarbon dating is one of the analytical methods used in archaeology and art history to determine the age of an object made up of materials from living organisms. Today, in the field of the arts, and particularly for paintings, the supports in wood, canvas or paper, and recently the binders of plant and animal origin are the only constituents of painted works accessible to this technique. However, the results coming from the supports do not always reflect the date of creation of the artwork because of the common reuse of these materials. In addition, the binder is not always organic or present in sufficient quantities. Finding other materials that can be dated by 14C is therefore important to authenticate a painting. Except black carbon made from charcoal or bone, most of the others constituents of the paint layers are not appropriate because they are generally inorganic pigments, extracted from natural ores and depleted in 14C.Lead white is a synthesized inorganic pigment, widely used from Antiquity to the very beginning of the 20th century. The study of the mechanism of its synthesis has recently highlighted the role of carbon dioxide in the formation of cerussite and hydrocerussite, the two lead carbonates that compose this pigment. Thus, by considering the incorporation of carbon during the synthesis, lead white seems to be a potential candidate for radiocarbon dating and for the authentication of painted artworks.This thesis work consisted in setting up experimental protocols based on the measurement of carbon isotopes (13C and 14C) in lead white based pigments and paints in order to test this hypothesis. A protocol for the extraction of carbon from lead carbonates was developed and adapted to the nature and complexity of the materials studied, raw or filled pigment and paint. The study is based on the thermal decomposition properties of lead carbonates and allows to determine the best conditions for carbon extraction. This method was then tested and validated on a large panel of model samples and historical samples of know age. In addition, the carbon isotopic data were related to the historical recipes and made it possible to discriminate between the different lead white production processes.This thesis demonstrates that lead white is an inorganic pigment that can be radiocarbon dated. The 14C measurement provides information on the date of its manufacture. The approach and protocols presented for this study could also be adapted to other inorganic paint pigments containing organic carbon, thus increasing the number of available materials for dating and authenticating pictorial works of art
Toro, Villegas Gloria Elena. « Tephrochronologie de la Colombie centrale (département d'Antioquia et abanico de Pereira) : une approche stratigraphique, géochimique, minéralogique et géochronologique (par C14 et traces de fission) ». Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10036.
Texte intégralFleche, Yves. « Synthèse de phénols et de naphtols diversement substitués : application aux composés marqués au carbone 14 ». Aix-Marseille 3, 1992. http://www.theses.fr/1992AIX30080.
Texte intégralGonzalez, Miguel. « Nature and origin of sedimentary deposits in the Ecuador subduction trench : paleoseismological implications ». Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1B009/document.
Texte intégralRecent deep marine sedimentation in subduction trenches is characterized by the inter-stratification of hemipelagic and turbidite sediments locally interbedded with debris flow, which can result from continental slope shaking triggered by earthquakes. The active margin of Ecuador comprises tectonic erosion that contributes to the formation of a deep trench filled by a complex suite of sedimentary facies. Gravity flow sedimentation is ubiquitous along the margin and facies range from laterally continuous m-thick mass transport deposits to isolated cm-thick turbidites intercalated with hemipelagite, volcanoclastics and tephra. In this study we show interpretation of swath bathymetry, high-resolution seismic profiles and petrophysical data from cores. The objective is to describe the morphologic complexity on the Ecuadorian border of the Nazca plate where a set of deep marine asperities is subducting at different scales, and their consequences on the distribution of sediments in the different sub-basins. Ecuadorian margin comprises three geomorphological segments: The northern segment, northward of the Carnegie Ridge, is characterized by a wide (5-10 km) and deep trench (3800 – 4000 m), a gentler gullied continental slope and a shelf (10-40 km wide) with active subsidence. The central segment facing the Carnegie Ridge, is strongly influenced by the subduction of the Carnegie ridge which induces a narrow (0–5 km wide) and shallow trench (3100 – 3700 m depth), a steep and gullied slope with no canyons and a 15–40 km wide shelf characterized by areas with active subsidence and uplift. Finally, the southern segment, southward of the Carnegie Ridge, presents a wide (5–10 km) and deep (4000–4700 m) trench, a starved continental slope with well-defined canyon systems and a wide subsiding shelf (20–50 km). The sedimentary dynamics along the margin is evaluated by the analysis of 15 cores. Visual description, high-resolution photographs, X-Ray imagery, XRF data and petrophysical properties led to the identification of 11 sedimentary facies that characterize seven sedimentary processes: turbidites, hemipelagites, tephras, debris flows, homogenites, slumps, and ooze carbonate deposits. Age of the deposits is defined by radiocarbon age dating of hemipelagic sediments. Ages range from 500 to 48,000 years BP. High-resolution seismic profiles allow definition of three echo-facies: transparent, layered and chaotic. Transparent echo-facies is mainly associated to homogenite deposits, layered echo-facies is associated to the turbiditic-hemipelagic interbedded deposits and chaotic echo-facies is associated to reworked gravity flow deposits. The trench fill represents a lacunar but important record of the subduction margin history. Large eastward debris flows in the lower two sequences of the trench fill are provided by the trench outer wall as a results of slope failures along normal faults due to the downward bending of the oceanic plate. The sediment of the upper sequence of the trench fill draping the trench floor, are largely provided by the inner trench wall strongly controlled by the Carnegie Ridge. As a result, depth, frequency, thickness, composition and lateral disposition of the deposits vary greatly from those at north and south. The large, simple mega-beds like slump, debris flows and homogenites are located at the northern and southern segments. They were triggered by large regional faults in the North and enhanced by the activity of sets of splay faults in the South overhanging the seafloor at the slope toe. Small-size, fluid rich events were triggered by subduction of isolated seamounts at the edges of the Carnegie Ridge due to frequent but small destabilizations of an inner trench wall preconditioned by the impacts of successive seamounts. Sets of partly volcanoclastic turbidites in central segment might have been triggered by the complex interaction of slope and continental shelf deformation by seamount subduction
Dandurand, Grégory. « Cavités et remplissage de la nappe karstique de Charente (bassin de la Touvre, La Rochefoucauld) : spéléogenèse par fantômisation, archives pléistocène et holocène, rôle de l'effet de site ». Bordeaux 3, 2011. https://extranet.u-bordeaux-montaigne.fr/memoires/diffusion.php?nnt=2011BOR30044.
Texte intégralThis PhD aims to study caves and subterranean karst infillings deposits from Charente (Touvre catchment) as a memory of past climate and environments. From the concept of site effect, the two studied caves (Bois du Clos and Fuie) show an original recording of the regional palaeoclimatic conditions of the Middle-Upper Pleistocene and of the Holocene. The prominent role of the ghost-rock processe during the long geological time of Lower Cretaceous (45 Ma) was demonstrated by the study of three quarries, drilling and the young cave of La Fuie. This alteration process explains the genesis of labyrinthic caves and also the complexity of the Touvre aquifer which supplies the city of Angoulême. Indeed the large water reserve is situated into the porous rock (slow drainage) while a small part is drained by the karst conduits (fast drainage coming from river losses). The geochemical, sedimentological and mineralogical studies of detrital infillings deposits into Bois du Clos and la Fuie allowed to characterize hydrosedimentary dynamics and palaeoenvironmental conditions between marine isotope stages 6 and 3, obtained by 14C et U/Th in speleothems of Bois du Clos cave. The microchemical imagery by X-ray fluorescence has highlighted the existence of some carbonated levels related to the process of speleogenesis by ghost rock and the major role of groundwater level fluctuations. The compared chronostratigraphic study of the regional speleological and archaeological sequences finally allowed reflecting the role of local and regional settings, as well as global parameters in palaeoclimate
Legendre, Yoann. « Reconstruction fine de l'histoire éruptive et scenarii éruptifs à la soufrière de Guadeloupe : vers un modèle intégré de fonctionnement du volcan ». Paris 7, 2012. http://www.theses.fr/2012PA077065.
Texte intégralIt is important for the Soufrière volcano to improve our reconstruction of the eruptive past over an extended period to elaborate refined and credible eruptive scenarios. In this doctoral thesis, we present the results of a new detailed chronology of the eruptive history of la Grande Decouverte - Soufrière (GDS) complex for the last 50 000 years. Our integrated approach is based on the stratigraphyic analysis of more than 250 new outcrops, 181 new radiocarbon age dates as well as on a sedimentologic study of cores newly obtained on the « Cendres Jaunes » unit. Combined with an exhaustive reinterpretation of older available data, our new chrono-stratigraphic data show that magmatic activity of la GDS complex is significantly higher than previously interpreted. Indeed, we have identified at least 28 eruptive events for the last 50 000 years of activity of the volcanic complex. Moreover, at least 15 eruptive events have occurred during the most recent Soufrière episode in the last 9150 years. Activity over the last 50 000 years consists of at least 21 major explosive eruptive phases showing a large range in magnitude, and at least 17 dome-forming eruptive phases of large magnitude characterized by an important explosivity. Finally, at least 16 recognized flank-collapse events are associated with these eruptive events. Our data suggests activity at La Soufrière of Guadeloupe is dominated by polyphasé eruptive events consisting of different phases of activity that occur over a short yet unknown span of time. The interpretation of these data allows us to elaborate credible eruptive scenarios for a future event at la Soufriere de Guadeloupe
Chabault, Christelle. « Identification des circulations souterraines dans le cas de deux aquifères sableux : Sables de Fontainebleau(78- Yvelines) et Sables de l'Astien (34- Hérault) ». Paris 11, 2006. http://www.theses.fr/2006PA112341.
Texte intégralTantau, Ioan. « Recherches pollenanalytiques dans les Carpates Orientales (Roumanie). Histoire de la végétation et de l'action humaine ». Aix-Marseille 3, 2003. http://www.theses.fr/2003AIX30049.
Texte intégralPaleoecological studies of five wetlands from the Eastern Romanian Carpathians and from the southwestern part of Transylvania depression were accomplished. Eleven pollen diagrams established by 1165 pollen spectra and supported by 64 14C datings make it possible to reconstitute the Late Glacial and Holocene vegetation history. Durind the Late Glacial interstadial the forest recolonisation begin with the Pinus developpement, without the Betula phase. Picea begin to expend from the refuges. After an Younger Dryas well marked, the Holocene begin with the Betula, Ulmus and Picea expansion, then, at about 9,000 BP, by that of Fraxinus, Quercus and Tilia. Corylus optimum is correlated with the Atlantic chronozone (after 8,000 BP), that of Carpinus is characteristic of Subboreal (at about 5,000 BP). The forests of Fagus are spread starting from 4,000 BP. The first evidences of cultivation of cereals appear around 6,500 B. P. The regional diachronisms evidences makes it possible to reconstitute the migration routes of some forest taxa
Philippot, Anne-Céline. « Approche géochimique et isotopique du fonctionnement actuel et passé des aquifères profonds de Belgique septentrionale ». Paris 11, 2000. http://www.theses.fr/2000PA112375.
Texte intégralThe hydrogeological and geochemical study of the Mol site (Belgium) was undertaken within the framework of the EC Project "PHYMOL" (palaeohydrology of the Mol Site). More specifically, the objectives of that study are to understand the hydrogeological behaviour of two deep aquifers, the Ruisbroek-Berg and the Lede-Brussel, confined by the Boom clay formation, in response to palaeoclimatic variations occuring during the last glacial cycle. Regional groundwater flow is from South (outcropping zone) to North. Ionic contents (particularly Cl and Br/Cl ratio) show a contribution of a marine component to groundwaters. That contribution increases from South to North. Both stable isotope (18O, 2H) and dissolved noble gages contents (Ne, Ar, Kr, Xe) in groundwaters probably indicate a "palaeoclimatic effect" in deep aquifers. Palaeotemperature reconstructions show variations in recharge temperature for the last 40 ka. Furthermore, a gap seems to appear in the 14C data, that could correspond to a period with very low recharge rate. That gap is recorded between 21 and 25 ka by the 14C contents of TDIC. However, 14C analyses on fulvic acids situate the gap between 21 and 15 ka, period which corresponds to the Last Glacial Maximum. It is possible that no recharge occured during this time, due to the climate aridity and the probable existence of a permafrost in the recharge area
Vignon, Violaine. « Activité hors séquence des chevauchements dans la syntaxe nord-ouest himalayenne : apports de la modélisation analogique et quantification quaternaire par analyse morphotectonique ». Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00771671.
Texte intégralStrechie-Sliwinski, Claudia. « Enregistrement sédimentaire des changements environnementaux récents dans la zone Nord-Ouest de la Mer Noire ». Paris 11, 2007. http://www.theses.fr/2007PA112178.
Texte intégralThe purpose of this study is to investigate the processes and the recent environmental changes stored in the sediments from the North-Western part of the Black Sea in the last 30,000 years. We used sedimentary cores extracted from water depths ranging from 55 to 2100 m. In order to obtain information about the depositional environment and the chronology of the events, we used different methods: clay mineralogy analysis, sedimentology, environmental magnetism, organic matter characteristics and AMS radiocarbon chronology. Radiocarbon dating of the organic matter and fossil shells was used to obtain a precise chronology of the past events. It was difficult to correct the 14C data, because of the differences between the ages of organic matter and shells that varied significantly from one sample to another. This difficulty comes from the fact that the Black Sea basin contained in some periods oxygenated fresh water and in some periods stratified salty water. The correlation between the 14C data and the carbonate content allowed us to set up a chronology of the sediments. The clay mineralogy pointed out that the sediments containing smectite were carried into the basin mainly from the North and not from the South of the drainage basin, as previous studies indicated. The environmental magnetism study helped us to determine the significant variations in the oxygenation of the sediment and of the water column (i. E. , changes between oxygenated and anoxic conditions). The magnetism study together with the organic matter characteristics also indicates changes in the salinity of the water. Our study reveals the environmental changes that have occurred during the last 30,000 years
Garnier, Jean-Marie. « Transport du carbone inorganique en solution : expérimentation et modélisation à différentes échelles (2.10⁻¹ , 10 et 10² à 10³ m) ». Paris 11, 1988. http://www.theses.fr/1988PA112391.
Texte intégralSévin-Allouet, Christophe. « Durabilité et hiérarchie des sépultures collectives dans le Nord-Ouest de la France et dans les Îles Britanniques (4500-2500 avant J. -C. ) ». Paris 1, 2011. http://www.theses.fr/2013PA010535.
Texte intégralCaner, Laurent. « Les sols humifères des Hautes Terres du massif des Nilgiri en Inde du Sud : formation d'andosols sur une ancienne couverture ferrallitique en relation avec les évolutions climatiques des derniers millénaires ». Nancy 1, 2000. http://www.theses.fr/2000NAN10009.
Texte intégralHigh elevation humiferous soils from the Nilgiri Hills may be considered as the result of a polycyclic genesis: the ferrallitic regoliths corresponding to an old pedogenesis under a tropical wet and hot climate; the present pedogenesis concerning only the surface humiferous horizons. The most humiferous soils are marked by the presence of high amounts of organo-metallic complexes and verify the criteria of identification of Andosols in recent soils classifications and are moreover non-allophanic. The Nilgiri Andosols developed on an ancient ferrallitic material present and original pedogenesis. In the absence of volcanic glasses and any other weatherable minerals the potential sources of aluminium and iron to form the organometallic complexes are the secondary oxides. Gibbsite and iron oxides, considered as stable minerals of ferrallitic weathering, are instable in acidic conditions and in presence of organic matter. Due to high amounts of oxides the organo-metalllic associations are provided with a substantial metallic charge which leads to the emergence of andic properties. 14C datings and δ13C of soil organic matter revealed that the formation of the organic matter-rich horizons was related to the existence of a cold period at the transition Pleistocene / Holocene with grassland vegetation. The study of these soils gives information on the processes of organic matter accumulation in soils at different periods and show that the characterisation of the organo-metallic complexes at different scales allows to understand the interactions of the organic matter with metallic-cations which is the key process of its stabilisation
Calmel-Avila, Maryvonne. « Géomorphogenèse holocène dans le Bas-Guadalentin : bassin du Segura, province de Murcie, Espagne ». Pau, 1998. http://www.theses.fr/1998PAUU1005.
Texte intégralThe topic of the research is in line with the geomorphology in the environment of human society. It deals with the analysis, organisation and interpretation of erosion processes in a semi-arid region for the last 10 000 years in levant, spain. The methodology consists of stratigraphic studies of sections along the river banks, carbon dating, palynologic and ceramic indentifications. This thesis is made up of three parts. The first part deals with the presentation of scientific approach and of geomorphologic, climatic and anthropic contexts. The second part gives over to holocene geomophologic processes through algeciras, librilla, murta and low-guadalentin watersheds'studies. The third part proposes an interpretation of great stage of holocene geomorphologic processes. They are due to an interaction between natural and anthropic factors
Quiles, Anita. « Construction d'une chronologie absolue pour la 18eme dynastie de l'Egypte ancienne par la méthode du carbone 14 en Spectrométrie de Masse par Accélérateur : modélisation bayesienne et simulations de transport de faisceau ». Paris 7, 2011. http://www.theses.fr/2011PA077080.
Texte intégralRadiocarbon dating is a well-tried method and a fundamental tool for archaeology. In the first part of this Project, we were interested in the instrumental aspect of measurements done on the ARTEMIS facility at the LMC14 laboratory. At first, we detailed how this facility operates. Then, we used complementary tools to simulate the transport of the beam through the different elements. Using the Transport tool, we obtained the optical spectrum of the beam, ensuring that there was no loss of beam, and identified the most sensitive points of the facility. Then, we used the GEANT4 tool-kit to simulate the interactions of the incident ions in different media. From these simulations we were able to establish the tolerances of the settings on electric and magnetic fields as well as the acceptance of the beam. Finally, the detector was optimized so as to subtract molecular ions C13H and C12H2 from the measurement of 14C ions. Next we showed that Bayesian statistics were a method that was relevant to the improvement of the precision of the results. We particularly focused our experiments on objects from the 18ft dynasty in Egypt. Objects conserved in the Dept. Of Egyptian Antiquities at the Louvre Museum and archaeologically attributed to a specific reign, were dated by radiocarbon analysis. The ages we obtained were constrained by archaeological and astrophysical evidence. We deduced a realistic range of dates for the beginning of each reign of the 18* dynasty. Finally, this new absolute chronology was tested on a specific study of objects coming from Gebel el-Zeit
Leduc, Sophie. « Émissions gazeuzes issues de déchets radioactifs solides ». Master's thesis, Université Laval, 2006. http://hdl.handle.net/20.500.11794/18588.
Texte intégralSabatier, Pierre. « Reconstitution des événements climatiques extrêmes (crues et tempêtes) au cours de l'holocène dans le golfe d’Aigues-Mortes (Sud de la France) ». Montpellier 2, 2009. http://www.theses.fr/2009MON20111.
Texte intégralThe effects of climate change on extreme events are difficult to assess because extremes present large variability and consequently, it is difficult to identify significant trends in relation to the lack of instrumental long time series. Here we present a record of these extreme storm events in the French Mediterrannean coast over the past 7000 years based on a long sediment core from lagoonal environment in Gulf of Lions. Using a high resolution multiproxies approach on core associating grain size, faunal to reconstruct Mid to Late Holocene history of backbarrier deposits in relation to landfalling activity. Even if change in lagoon geomorphological setting over the Holocene does not allow to compare storm events in terms of intensity trough time, we have recorded six periods of increase in storm activity at 6200, 5500, 4400, 3200, 1500 yr cal B. P. And over the LIA (450 and 100 yr cal B. P. ). These evidences of changes in coastal hydrodynamic, inversely correlated to periods of aridification in Western Mediterranean region, are in phase with those observed over the North Atlantic and correspond to Holocene cooling events. This increase in storm activity during Holocene cold events over Mediterranean region was probably due to thermal gradient increase leading to enhanced lower tropospheric baroclinicity over a large Central Atlantic-European domain. This study demonstrates that temperatures in North Atlantic region influence the severe storm activity and therefore the Mediterranean climate at Holocene timescale
Duhamel, Maxence. « Restitution des changements de l’hydrologie des masses d’eaux intermédiaires et profondes de la Méditerranée au cours des derniers 145 ka à partir de la mesure de la composition isotopique du Nd de foraminifères Variations in eastern Mediterranean hydrology during the last climatic cycle as inferred from neodymium isotopes in foraminifera Changes in the intermediate water masses of the Mediterranean Sea during the last climatic cycle - new constraints from neodymium isotopes in foraminifera ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS120.
Texte intégralThis thesis aims to advance our knowledge of the hydrology of the intermediate and deep water masses of the Mediterranean during the last climatic cycle (last 145 ka), and to constrain the ocean circulation models that allowed the deposition of organic matter-rich sediments (ENT and sapropels). The Nd isotopic composition (εNd) of foraminifera samples in cores located at intermediate and deep bathymetries of the Tyrrhenian Sea, the Adriatic Sea, the Ionian Sea and the Levantine Basin were analyzed. This work allowed to highlight that the intermediate and deep waters of the Eastern Mediterranean are systematically more radiogenic during the glacial stadiums than during the interglacials. We have shown that these changes cannot be entirely attributed to variations in dust and river inputs from northern Africa but to significant changes in the amount of Atlantic (AW) water entering the Mediterranean. Periods of low sea ice levels are associated with a reduction in Atlantic water flows through the straits of Gibraltar and Siculo-Tunisia by inducing more radiogenic deep-water masses in the eastern Mediterranean. Superimposed on these glacial-interglacial fluctuations, African humid periods and sapropel deposits are systematically characterized by more radiogenic εNd values. This has been attributed to the cessation of deep convection of less radiogenic surface water associated with an increase in the contact time of deep-water bodies with radiogenic sediments from the continental margins of the Levantine basin. Our results highlight during terminations I and II an increase in the contribution of less salty water of North Atlantic origin (MAW) of around 55% which may have pre-conditioned the eastern Mediterranean several thousand years before the deposit S1 and S5 sapropels. A comparison of the εNd recordings obtained in the Eastern and Western basins over the last climate cycle shows a stronger gradient of εNd between the two basins at intermediate and deep depths during the glacial stadiums. This is consistent with a weaker water exchange across the Siculo-Tunisian Strait during periods of low sea ice. On the contrary, during the high sea levels of the interglacial periods, water exchanges are stronger between the two basins, inducing a transfer to the Tyrrhenian Sea of variations in the isotopic composition of Nd observed in the eastern Mediterranean. Thus, the African wet periods inducing a stratification of the water masses and the deposits of sapropels in the east, are associated with signatures of more radiogenic waters which are then transported by the LIW in the Tyrrhenian Sea. Superimposed on these orbital variations, rapid variations in εNd could be highlighted in the Corsica channel. Each cold event in the high latitudes of the Northern Hemisphere (Younger Dryas and Heinrich events) is characterized by a more radiogenic LIW in the Tyrrhenian Sea involving a reduction in the formation of intermediate water in the Gulf of Lion (linked to more strong freshwater inflows from the Atlantic during the Heinrich events) and / or a greater production of LIW in the eastern Mediterranean (linked to a cooling of the northern Mediterranean surface during the Heinrich events)
Rolland, Yann. « De la convergence intra-oceanique a l'evolution post-collisionnelle : exemple de la convergence indo-asiatique en himalaya du nord-ouest, du cretace a nos jours ». Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10220.
Texte intégralMohaseb, Karimlu Fatemeh. « Exploitation des animaux de l'Âge du Bronze au début de la période Islamique dans le Nord-ouest de l'Iran : l'étude archéozoologique de Haftavan Tepe ». Paris 1, 2012. http://www.theses.fr/2012PA010649.
Texte intégralDelmas, Magali Danielle. « Chronologie et impact géomorphologique des glaciations quaternaires dans l'est des Pyrénées ». Paris 1, 2009. http://www.theses.fr/2009PA010644.
Texte intégralBouchet, Gilles. « Mélanges magmatiques et genèse des granitoïdes calco-alcalins : l'exemple du complexe tonalo-granodioritique de Bono (Sardaigne septentrionale) : étude pétrologique et géochimique ». Saint-Etienne, 1992. http://www.theses.fr/1992STET4022.
Texte intégralMeurisse, Murielle. « Enregistrement haute résolution des massifs dunaires Manche, mer du Nord et Atlantique : le rôle des tempêtes ». Lille 1, 2007. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2007/50376-2007-347.pdf.
Texte intégralDemory, François. « Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia) ». Phd thesis, Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2005/181/.
Texte intégralLake Baikal provides an excellent climatic archive for Central Eurasia as global climatic variations are continuously depicted in its sediments. We performed continuous rock magnetic and paleomagnetic analyses on hemipelagic sequences retrieved from 4 underwater highs reaching back 300 ka. The rock magnetic study combined with TEM, XRD, XRF and geochemical analyses evidenced that a magnetite of detrital origin dominates the magnetic signal in glacial sediments whereas interglacial sediments are affected by early diagenesis. HIRM roughly quantifies the hematite and goethite contributions and remains the best proxy for estimating the detrital input in Lake Baikal. Relative paleointensity records of the earth′s magnetic field show a reproducible pattern, which allows for correlation with well-dated reference curves and thus provides an alternative age model for Lake Baikal sediments. Using the paleomagnetic age model we observed that cooling in the Lake Baikal region and cooling of the sea surface water in the North Atlantic, as recorded in planktonic foraminifera δ18 O, are coeval. On the other hand, benthic δ18 O curves record mainly the global ice volume change, which occurs later than the sea surface temperature change. This proves that a dating bias results from an age model based on the correlation of Lake Baikal sedimentary records with benthic δ18 O curves. The compilation of paleomagnetic curves provides a new relative paleointensity curve, “Baikal 200”. With a laser-assisted grain size analysis of the detrital input, three facies types, reflecting different sedimentary dynamics can be distinguished. (1) Glacial periods are characterised by a high clay content mostly due to wind activity and by occurrence of a coarse fraction (sand) transported over the ice by local winds. This fraction gives evidence for aridity in the hinterland. (2) At glacial/interglacial transitions, the quantity of silt increases as the moisture increases, reflecting increased sedimentary dynamics. Wind transport and snow trapping are the dominant process bringing silt to a hemipelagic site (3) During the climatic optimum of the Eemian, the silt size and quantity are minimal due to blanketing of the detrital sources by the vegetal cover.
Le, Dantec Théo Aurélien. « Dissolved organic matter characterization in a large arctic river : origins and dynamic ». Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0001/document.
Texte intégralArctic regions are expected to be highly sensitive to climate change regarding the prediction of disproportionately large increases in surface temperatures and their related influence over the hydrological cycle and permafrost thaw. These modifications have the potential to impact biogeochemical cycles in these regions and in particular the mobilization of organic carbon into rivers. The most crucial period in arctic rivers hydrological cycle is the spring freshet that can account for most of the annual organic carbon transfers to the ocean in a very short window of time. The focus of this thesis was to monitor the dynamic of DOM in terms of quantity and quality along the hydrological cycle of the Yenisei river, through DOM characterization approaches to reveal seasonal variations in its composition, sources, age and degradation state. The first step was to make a review of the full range of existing DOM characterization approaches in worldwide river systems to identify the most widely used, the most relevant and reliable ones. Through the development of a DOM quality measurements database, we have been able to evaluate the geographical coverage of DOM characterization studies, to give estimates and ranges of values of the main reported DOM characterization variables and to observe global trends of DOM quality across latitudinal gradient. Second stage was to investigate DOC dynamic in the Yenisei river with regard to quantity and links with water chemistry and hydrology. We conducted sampling campaigns during three consecutive years (2014 to 2016), covering with a high sampling frequency the spring flood period to capture its very dynamic evolution. We reported DOC concentrations that followed the hydrograph with highest concentrations observed a few days before peak discharge. DOC concentration also responded to discharge variation (increase, likely due to higher precipitation) in early autumn. We reported average DOC flux over the three sampling years of about 4.53 Tg yr-1 which is within the range of values reported in the literature. We observed interannual variability with annual export estimates ranging from 5.45 Tg yr-1 in 2014 to 3.57 Tg yr-1 in 2016, likely driven by discharge amplitude. We confirmed the important role of spring freshet in DOC export with on average more than 65% occurring during this period (roughly May/June). Third point was to determine DOM quality combining characterization techniques. Combination of approaches helped to strengthen observations and cross validate interpretations. Most of the variables reported from the different characterization techniques confirmed one each other. The use of lignin biomarkers, optical properties and radiocarbon age of DOM allowed us to trace DOM main sources has primarily deriving from recently produced organic matter leached from boreal forest litter and top soil horizon during the spring flood and older organic matter derived from deeper soil horizons during low flow period
Toro, Villegas Gloria. « Tephrochronologie de la Colombie centrale (departement d'Antioquia et Abanico de Pereira) : une approche stratigraphique, géochimique, minéralogique et géochronologique (par 14C et traces de fission) ». Phd thesis, 2006. http://tel.archives-ouvertes.fr/tel-00710305.
Texte intégralMASTROLONARDO, GIOVANNI. « The impact of wildfires on the abundance, composition and recalcitrance of soil organic matter ». Doctoral thesis, 2013. http://hdl.handle.net/2158/802673.
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