Thèses sur le sujet « Euxinie »

Les microbialites sont des structures organo-sédimentaires formées par les interactions entre des communautés microbiennes benthiques et des phases minérales. Certaines se développent actuellement alors que les plus anciennes, sous forme fossile, sont datées jusqu’à ~3,43 Ga et comptent parmi les plus anciennes traces de vie non-ambigües connues sur Terre. Par conséquent, les microbialites fournissent des informations précieuses sur la paléobiologie et les paléoenvironnements. Pourtant, malgré l’importance géobiologique de ces objets, leurs conditions et processus de formation sont encore peu compris. En particulier, des microbialites anciennes se sont vraisemblablement formées dans des conditions anoxiques, ce qui peut avoir des conséquences majeures sur la disponibilité des espèces chimiques en solution. Or, la plupart des microbialites actuelles, utilisées comme analogues des microbialites anciennes, se forment dans des environnements oxiques. Ceci confronte nos interprétations des paléobiologies et des paléoenvironnements à un manque de données sur la formation des microbialites en anoxie, et sur l’acclimatation/l’adaptation de leurs communautés microbiennes au cours du temps dans ces conditions. Ici, nous nous sommes intéressés à des microbialites actuelles découvertes dans des zones profondes saisonnièrement anoxiques de deux lacs alcalins : Alchichica et Atexcac (Mexique), en couplant des études de la minéralogie, de la diversité des microorganismes, de la géochimie des solutions et de la spéciation des éléments chimiques. Dans un premier temps de cette thèse, nous proposons, après avoir mis en place une base de données des microbialites actuelles connues, que les eaux où se forment les microbialites doivent être saturées vis-à-vis de phases carbonatées précurseurs et solubles comme les carbonates de calcium amorphes (ACC) et la monohydrocalcite, et que ce critère géochimique explique la présence ou non de microbialites dans des environnements actuels. Nous montrons ensuite un enregistrement des états redox de la colonne d’eau non seulement par la minéralogie des microbialites profondes via des signatures dans la spéciation du soufre déterminées par des analyses en spectroscopie d’absorption X synchrotron, mais aussi par les communautés microbiennes via des fluctuations d’abondances taxonomiques relatives identifiées par metabarcoding. Enfin, nous démontrons que les microbialites actuelles du lac Alchichica sont soumises à de la diagenèse précoce, conduisant à la formation de phases minérales rares comme la huntite, et ce notamment de manière différente en profondeur dans la colonne d’eau<br>Microbialites are organo-sedimentary structures formed by interactions between benthic microbial communities and mineral phases. Some are currently developing, while the oldest, in fossil form, have been dated back to ~3.43 Ga and are among the oldest traces of non-ambiguous life known on Earth. Consequently, microbialites provide valuable information on paleobiology and paleoenvironments. However, despite the geobiological importance of these objects, their formation conditions and processes are still poorly understood. In particular, ancient microbialites are likely to have formed under anoxic conditions, which can have major consequences for the availability of chemical species in solution. However, most modern microbialites, used as analogues of ancient microbialites, form in oxic environments. This confronts our interpretations of paleobiologies and paleoenvironments with a lack of data on the formation of microbialites in anoxia, and on the acclimation/adaptation of their microbial communities over time in these conditions. Here, we have focused on modern microbialites discovered in seasonally anoxic deep zones of two alkaline lakes: Alchichica and Atexcac (Mexico) by combining studies of mineralogy, microorganism diversity, solution geochemistry and chemical element speciation. In the first part of this thesis, after setting up a database of known modern microbialites, we propose that the waters where microbialites form must be saturated with precursor and soluble carbonate phases such as amorphous calcium carbonates (ACC) and monohydrocalcite, and that this geochemical criterion explains the presence or absence of microbialites in modern environments. We then show a record of water column redox states not only by the mineralogy of deep microbialites via signatures in sulfur speciation determined by synchrotron X-ray absorption spectroscopy analyses, but also by microbial communities via fluctuations in relative taxonomic abundances identified by metabarcoding. Finally, we demonstrate that the modern microbialites of Lake Alchichica undergo early diagenesis, leading to the formation of rare mineral phases such as huntite, and in particular differentially at depth in the water column

The depositional environment that existed during the accumulation of Devonian - Mississippian black shales of the eastern US has been a topic of debate in recent decades. In this study, pyrite framboid size distribution was evaluated for four cores from the Devonian outcrop belt of central Kentucky to determine the role that anoxic-euxinic conditions may have played in the accumulation of these black shales. For samples from the Appalachian Basin, pyrite framboid size distributions suggest that the Sunbury Shale and the upper part of the Huron Shale Member of the Ohio Shale were deposited under predominantly euxinic conditions, whereas the lowermost part of the Huron Member and the Cleveland Member of the Ohio Shale were deposited under predominantly dysoxic to oxic conditions. For samples from the Illinois Basin, pyrite framboid size distributions suggest that the Clegg Creek and the Morgan Trail members of the New Albany Shale indicate dysoxic to oxic conditions were present, whereas data for the Camp Run Member suggest the sediments were deposited during repeated intervals of euxinic deposition followed by predominant dysoxic - oxic conditions which allowed development of the bioturbated fabric seen in these gray shales. These results are not completely in agreement with previous research that utilized C-S-Fe and trace element relationships to establish depositional conditions during organic-rich sediment accumulation. For example, previous research has indicated that the Cleveland Member of the Ohio Shale and the Clegg Creek Member of the New Albany Shale were deposited under euxinic conditions. Reasons for these differences in interpretation may include syngenetic and diagenetic processes including winnowing of framboids in the depositional environment and atypical growth of the framboids.

On se propose d’élaborer une nouvelle vision des échanges entre les cités grecques du littoral occidental de la mer Noire et le reste du monde grec de l’époque classique à l’époque hellénistique. En étudiant ces cités de Nikônion à Apollonia, dans une perspective économique, cette thèse se propose de découvrir si elles ont des caractéristiques économiques semblables et si elles suivent le même rythme de développement. Ceci pourra aider à vérifier dans quelle mesure ces cités, qui ont des relations commerciales intenses, peuvent être regroupées en un ensemble économique cohérent. On devra identifier également les acteurs de ces échanges, ainsi que les produits échangés, dont certains (céréales, poissons, esclaves...) n’ont laissé que peu de traces dans les sources archéologiques, épigraphiques et littéraires. La recherche inclut les relations avec les populations et les royaumes de l’hinterland qui influent sur l’exploitation des territoires ruraux de ces cités et qui sont des partenaires commerciaux. Cette recherche permettra de comparer le fonctionnement des échanges avec d’autres parties du Pont-Euxin, notamment le Pont Nord où l’influence d’Athènes est importante durant le IVe siècle. Le but est de pouvoir comparer les flux observés dans l’espace pontique avec ceux existant dans d’autres régions grecques<br>We intend to develop a new understanding of the trade between the Greek cities of the western coast of the Black Sea and the rest of the Greek world during the Classical and Hellenistic periods. By studying these cities from Nikonion to Apollonia, from an economic perspective, this thesis aims to discover if they have similar economic characteristics and if they follow the same rythm of development. This may help to see how these cities, which have intense trade relations can be grouped into a cohesive economic unit. We will also identify in these exchanges the actors and the traded products, some of which (cereals, fish, slaves ...) have left little traces in the archaeological, epigraphic and literary sources. The research includes the relationship with the population and kingdoms of the hinterland that affect the exploitation of rural areas of these cities and are trade partners. This research will compare the exchanges with other parts of the Black Sea, including the northern part where the Athenian influence is important during the 4th century. The goal is to compare the flow observed in the Pontic area with those existing in other regions of Greece<br>Ne propunem să elaborăm aici o nouă viziune a schimburilor între cetăţile greceşti de pe țărmul occidental al Mării Negre și restul lumii greceşti, din epoca clasică până în epoca elenistică. Studiind aceste cetăţi, de la Nikonion la Apollonia, într-o perspectivă economică, teza de față îşi propune să afle dacă respectivele cetăţi au caracteristici economice asemănătoare și dacă urmează acelaşi ritm de dezvoltare. Aceasta ne va putea ajuta să verificăm în ce măsură aceste cetăţi, care au relații comerciale intense, pot fi grupate într-un ansamblu economic coerent. Va trebui să identificăm de asemenea actorii acestor schimburi, ca și produsele schimbate, dintre care unele (cereale, pește, sclavi…) nu au lăsat decât puține urme în sursele arheologice, epigrafice și literare. Cercetarea include relațiile cu populațiile și regatele din hinterland care își exercită influența asupra exploatării teritoriilor rurale ale acestor cetăţi și care sunt parteneri comerciali. Această cercetare ne va permite să comparăm felul în care funcţionau schimburile cu alte zone ale Pontului Euxin, în special cu Pontul Nord, unde influența Atenei este importantă pe parcursul secolului al IV-lea. Scopul este acela de a putea să comparăm fluxurile observate în spațiul pontic cu cele existente în alte regiuni grecești

Photic-zone euxinia (PZE) is associated with several times in Earth's history including Phanerozoic extinction events and long parts of the Proterozoic. One of the best modern analogues for extreme PZE is Mahoney Lake in British Columbia, Canada where a dense layer of purple sulfur bacteria separate the oxic mixolimnion from one of the most sulfidic monimolimnions in the world. These purple sulfur bacteria are known to produce the carotenoid okenone. Okenone's diagenetic product, okenane, has potential as a biomarker for photic-zone euxinia, so understanding its production and transport is important for interpreting the geologic record. In the following dissertation, I examine Mahoney Lake with a multi-proxy approach. I use lipid biomarkers to understand organic matter production burial in the lake and find strong evidence of lateral transport of organic matter from shoreline microbial mats to the lake-bottom sediments. I also find evidence of okenone production in these shoreline mats and a carotenoid previously unreported in the environment, Thiothece-484, associated with the okenone synthetic pathway. Finally, I develop a new bioinformatics method to examine high-throughput metagenomic data and use this method to start understanding how the metabolic and lipid synthetic pathways of microbial communities in the lake are associated with each other.<br>Earth and Planetary Sciences

Le bassin de Cariaco représente un emplacement idéal pour l’étude de la préservation de la matière organique (MO) en particulier la sulfuration naturelle, car il a présenté des conditions euxiniques récurrentes au cours de son histoire. Pour contraindre les processus de préservation de la MO, nous avons étudié les sédiments varvés du bassin de Cariaco sur une période de 130 ka. Nous avons mis au point un protocole basé sur des hydrolyses séquentielles permettant d’isoler des kérogènes libres d'artefacts. Ce protocole a permis de libérer d’importantes quantités de carbohydrates représentant jusqu'à 3% du carbone organique total. Ces carbohydrates d’origine algo-bactérienne présentent une diminution en profondeur lié à des processus de dégradation in situ et/ou à l’incorporation dans la matrice macromoléculaire. L’étude des marqueurs moléculaires présents dans les extraits organiques corrobore l’origine principalement autochtone de la MO. Cependant la contribution des végétaux terrestres a été mise en évidence dans les échantillons correspondant aux périodes glaciaires. Le processus de sulfuration naturelle a un rôle important dans la préservation de la MO à Cariaco. La sulfuration intramoléculaire est indiquée par la présence des thiophènes et thiolanes à l’état libre. La désulfuration au nickel de Raney et la pyrolyse des kérogènes révèlent également une sulfuration intermoléculaire. La sulfuration ne présente pas une tendance générale à l’augmentation dans l’intervalle étudié. Le processus se révèle sensible aux variations climatiques, et facteurs tels que les conditions redox du milieu et la disponibilité et réactivité des précurseurs moléculaires<br>The Cariaco basin provide an ideal location to study the organic matter (OM) preservation processes in particular the natural sulfurization, since it has presented recurrent euxinic conditions along its history. To better understand the OM preservation processes, we have studied the varved sediments of Cariaco in a time interval of 130 ky. In this study, we have employed an artifact free method based on stepwise hydrolysis for the isolation of kerogen. This method permitted to obtain important amounts of monomeric carbohydrates, accounting for up to 3% of the total organic carbon. Those algal/bacterial-derived carbohydrates present a decrease with depth related to in situ degradation and/or incorporation to the macromolecular matrix. The investigation of the organic extracted biomarkers corroborate the authochtonous origin of the OM. Nevertheless, an important contribution of terrestrial OM was observed in the samples from glacials periods. The natural sulfurization process have an important role in the preservation of OM in Cariaco basin. The intramolecular sulfurization was revealed by the presence of free alkylthiophenes and thiolanes. Raney nickel desulfurization and kerogen pyrolysis also revealed intermolecular sulfurization. The natural sulfurization does not present a global increase in the time interval studied. This process respond to variations in climatic conditions, redox conditions in the water column and sediments and also to the reactivity and availability of the molecular precursors

Reconstruction of basin-scale paleogeography and paleoenvironments in the northern Perth Basin during the Early Triassic, utilising integrated geological and organic geochemical analyses, shows the distribution of photic zone euxinia and microbial mats following the end-Permian mass extinction. Such analyses also distinguish the organic geochemical signatures of photic zone euxinia and microbial mats, identify source rock potential across the basin, and have implications for the petroleum system in both the northern Perth and Northern Carnarvon basins.

Recherche de témoignages sur les échanges en mer Noire à l'époque archaîque (fin VIIème siècle-1er quart Vème siècle) recouvrant le commerce maritime entre colonies grecques et métropoles, le commerce entre colonies et les échanges avec les peuples autochtones, notamment Scythes et peuples sédentarisés de la steppe boisée. Examen des sources écrites littéraires et épigraphiques, des découvertes archéologiques et des monnaies. En 2ème partie, analyse détaillée des échanges : vin et huile (amphores), céramique, métaux, céréales, esclaves, sel et poisson, objets précieux, objets divers (bois, produits alimentaires, textiles, cuirs et fourrures, plantes. . . ). Evocation des acteurs des échanges (aristocrates ou marchands enrichis des cités de Grèce de l'Est, marchands vivant dans les colonies ou autochtones hellénisés). Traitement de quelques aspects techniques : routes maritimes, fluviales ou terrestres, rôle de l'Etat (réglementations, appareil judiciaire, poids et mesures, monnaies).

Thesis: Ph. D., Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Tracing the evolution of Earth's redox history is one of the great challenges of geobiology and geochemistry. The accumulation of photosynthetically derived oxygen transformed the redox state of Earth's surface environments, setting the stage for the subsequent evolution of complex life. However, the timing of the advent of oxygenic photosynthesis relative to the Great Oxidation Event (GOE; -2.4 Ga) is poorly constrained. After the deep ocean became oxygenated in the early Phanerozoic, hydrogen sulfide, which is toxic to most aerobes, may have transiently accumulated in the marine photic zone (i.e. photic zone euxinia; PZE) during mass extinctions and oceanic anoxic events. Here, the molecular fossil evidence for oxygenic photosynthesis and eukaryotes is reevaluated, where the results imply that currently existing lipid biomarkers are contaminants. Next, the stratigraphic distribution of green and purple sulfur bacteria biomarkers through geologic time is evaluated to test whether these compounds reflect a water column sulfide signal, which is implicit in their utility as PZE paleoredox proxies. Results from a modern case study underscore the need to consider allochthonous and microbial mat sources and the role of basin restriction as alternative explanations for these biomarkers in the geologic record, in addition to an autochthonous planktonic source.<br>by Katherine L. French.<br>Ph. D.

Influencés par les événements, la fin du XIXème siècle et notamment par le démantèlement de l’Empire ottoman, les notables grecs pontiques se sont regroupés autour d’un mouvement pour concrétiser un idéal, celui de faire revivre l’État pontique qui avait existé deux mille ans auparavant dans la Région de la mer Noire (actuellement au nord de la Turquie). Ce mouvement, né à la suite de la révolution jeune turque de 1908, prit de l’ampleur au cours des guerres balkaniques de 1911-1912, puis se consolida avec la guerre mondiale de 1914. Le mouvement pontique avait trois objectifs principaux : -L’annexion de la région à la Grèce. Gérmanos Kavanghélis, le métropolite d’Amasya et Samsun, soutenait fortement ce projet. -la création d’un État indépendant du Pont. Cette idée était le fait du Patriarcat orthodoxe de Constantinople, du lobby pontique en Europe et de certains dirigeants religieux locaux, comme Chrysanthos Philippidès, le métropolite de Trabzon. -la création d’une confédération autonome ponto-arménienne. Les événements qui firent suite à la Révolution bolchevique de 1917 réveillèrent l’enthousiasme de la diaspora pontique en Turquie, en Russie, en Grèce, aux États-Unis et en Europe. Ils tentèrent, dés lors, de se faire entendre lors de la Conférence internationale de la Paix de Paris (18 janvier 1919- août 1920). Cependant, ils n’étaient pas capables de constituer un groupe de pression suffisamment fort pour imposer leur projet. Ainsi, les puissances occidentales semblaient peu enclines à satisfaire les revendications des Grecs pontiques. Finalement, après la défaite de l’Armée grecque en Asie Mineure et la migration forcée suite au traité de Lausanne (le 24 juillet 1923) ont abouti à une élimination presque totale de la présence des Grecs du Pont dans la région de la mer Noire<br>Influenced by the events of the time, by the expiry of the 19th century and especially by the dismantlement of the Ottoman Empire, the Greek Pontic notables were grouped around a movement in order to concretize an ideal: to revive the Pontus State which had existed two thousand years ago in the Black Sea region (actually in the north of Turkey). This movement, which had appeared after the 1908 Young Turk revolution, intensified during the 1911-1912 Balkan Wars, and consolidated with the First World War in 1914. The Pontic movement had 3 principal objectives: Annexation of the region to Greece. Germanos Kavanghelis, metropolitan of Amasya and Samsun, strongly supported this project. Creation of an independent Pontus State. This idea was upheld by the Orthodox Patriarchate in Constantinople, by the Pontus lobby in Europe and by certain local religious administrators like Chrysanthos Philippides, metropolitan of Trabzon. Creation of an autonomous Pontic –Armenian confederation. The events that were experienced after the 1917 Bolchevik Revolution aroused enthusiasm among the Pontus diaspora in Turkey, Russia, Greece, the US and Europe. Thereupon, they tried to explain themselves during the Paris International Peace Conference (January 18, 1919- August 1920). However, they were not capable to constitute a pressure group that was strong enough to impose their project. Thus, the western powers seemed less inclined to satisfy the Pontus Greek revendications. Finally, the defeat of Greek army in Minor Asia and the forced migration following the treaty of Lausanne (July 24, 1923) gave way to the nearly total elimination of Pontic Greeks in the Black Sea region

High Hydrostatic Pressure (HHP) application, alone or in combination with refrigeration, ambient or moderate heating temperatures<br>inactivates pathogenic and spoilage microorganisms and conserves the product &bdquo<br>&bdquo<br>freshness

The Toarcian Oceanic Anoxic Event (T-OAE; ~183 million years ago) represents an interval during the Mesozoic when the emplacement of the Karoo-Ferrar Large Igneous Province (LIP) is thought to have resulted in significant environmental change. Associated with this interval was the widespread deposition of organic-rich sediments, carbon cycle and seawater chemistry changes, global warming, the development of marine anoxia, and major extinction events. The majority of studies of this event that have documented these responses have come from the Boreal and Tethyan regions of Europe, thus casting some doubt to the regional versus global significance of the event. Thus my dissertation has sought to reconstruct biogeochemical and paleoenvironmental changes across the T-OAE from a sedimentary succession that was deposited on the margins of a different ocean basin away from the well-studied European successions. Specifically, I have studied the chemostratigraphy of the Fernie Formation of the Western Canada Sedimentary Basin (WCSB), which was deposited on the eastern margin of the Panthalassa Ocean. The Toarcian carbon isotope excursions (CIEs) in the WCSB confirm that these features are global phenomena. I have suggested a new driver for small-scale CIEs observed during the event: the release of wetland-derived methane during progressive global warming. The osmium isotope record and numerical modeling of the osmium cycle suggests that continental weathering rates increased during the T-OAE by 230 – 540%. Rhenium abundance data also suggests that the increased geographic extent of marine anoxia during the T-OAE caused a global drawdown in the seawater rhenium inventory. Iron speciation data are used to reconstruct redox conditions within the WCSB, which suggest ferruginous conditions developed in the more distal locations at the onset of the T-OAE before returning to euxinic (anoxic and sulfidic) conditions. This is likely related to enhanced pyrite burial on a global scale, which caused the drawdown of the seawater sulfate inventory, thus limiting pyrite formation in the distal locations. The proximal setting remained euxinic across the T-OAE, and in all locations the iron speciation data suggest anoxic conditions persistent well after the interval that has been traditionally called the end of the T-OAE.<br>Ph. D.

Mégare a été l'une des cités les plus actives de la Grèce antique en matière de colonisation puisqu'elle a participé entre les VIIIe-VIe siècles av. J. -C. à la fondation d'un nombre important d'établissements autant en Sicile (Mégara Hyblaea et Sélinonte) qu'en Propontide (Astacos, Chalcédoine, Olbia, Sélymbria et Byzance) et dans le Pont-Euxin (Héraclée du Pont et Mésambria). Pour comprendre le mouvement mégarien de colonisation, nous avons divisé notre recherche en trois grandes parties. La première se propose d'examiner quelques événements de l'histoire archaïque de Mégare, à savoir la formation de l'État mégarien et les rapports de la cité avec Corinthe et Athènes, en traitant simultanément du développement et des conflits internes de la société mégarienne. En second lieu, nous nous penchons sur les fondations mégariennes, en mettant l'accent sur l'occupation globale du territoire, sur les relations entre les différents groupes d'apoikoi ("premiers colons ") et d'époikoi ("colons ultérieurs") grecs et sur les contacts avec les indigènes. La troisième partie porte sur les institutions politiques (subdivisions civiques et magistratures) d'origine mégarienne attestées dans les colonies fondées par Mégare. En examinant les causes de la colonisation mégarienne, nous soulignons le rôle important joué dans ce mouvement d'expansion par la compétition et les conflits entre les familles aristocratiques. Nous considérons par ailleurs que les colonies mégariennes furent le résultat d'un synœcisme primitif, d'un rassemblement de plusieurs groupes de colons le plus souvent hétéroclites du point de vue ethnique<br>Megara was one of the most active cilies of ancient Greece in term of colonization because she participated between the VIIIth-VIth centuries B. C. In the foundation of a significant number of settlements in Sicily (Megara Hyblaea and Selinous), the Propontis (Astakos, Chalcedon, Olbia, Selymbria and Byzantium) and the Black Sea (Herakleia Pontica and Mesambria). For the understanding of the Megarian colonization, we divided our research into three great parts. In the first one, we examine some events of the ancient history of Megara, especially the founding of the Megarian state, the relationships of Megara with the neighbouring cities of Corinth and Athens, the development of the Megarian society and the internal conflicts. In the second place, we consider the foundation of the Megarian colonial settlements, by stressing the global occupation of the territory by the colonists or the relations between the various groups of colonists, namely between the apoikoi ("first colonists") and the epoikoi ("later colonists"). We also examine the first rapports between Greeks and the indigenous peoples. Finally, the third part of the thesis relates to the political institutions (civic subdivisions and magistracies) of Megarian origin attested in the colonies. By examining the causes of the Megarian colonization, we underline the important part played in this movement of expansion by the competition and the conflicts between the aristocratic families. We consider in addition that the Megarian colonies were the result of an original synoikism, of a gathering of several groups of colonists, most often ethnically heterogeneous

La présence iranienne dans les régions pontiques, bien qu’apparaissent de manière incidente dans de nombreuses études, n’a jamais fait l’objet d’une thèse de doctorat. Ce travail de thèse se propose de retracer l’histoire de la présence des Iraniens dans les régions pontiques des origines à la chute de l’Empire achéménide. Dans la première partie de notre thèse, nous passons en revue les discussions les plus récentes sur l’origine, les stades de la formation et la répartition des populations nomades iranophones dans les steppes eurasiatiques. Nous nous penchons notamment sur les rasions du passage au grand nomadisme pastoral monté de ses tribus à l’aube du Ier millénaire avant J.-C. Dans la deuxième partie de notre thèse, nous retraçons d’abord l’histoire du peuple cimmérien, puis nous traitons in extenso du problème de leur appartenance linguistique et anthropologique. Dans cette partie sont également examiné l’origine de la culture de la Scythie du Pont, l’établissement des Scythes en Asie antérieures et leur retour aux steppes nord-pontiques. A la fin de cette partie, nous reprenons l’analyse de la première légende d’origine des Scythes rapportée par Hérodote et nous tentons, en utilisant la méthode comparative dumézilienne, de démontrer que les éléments constitutifs de cette légende sont la résurgence et l’assemblage de schémas narratifs des mythes fondateurs des peuples iraniens. La troisième partie de notre thèse est consacrée à l’étude de la présence iranienne dans les régions pontiques à l’époque achéménide. Nous nous appliquons à dresser le portrait historique de ces espaces géographiques sous la domination achéménide et nous tentons d’identifier les traces de l’occupation achéménide ainsi que les « marqueurs » de la présence iranienne dans ces régions. Les documents de natures diverses et complémentaires permettent de confirmer non seulement la présence iranienne, mais aussi la profondeur des contacts inter-culturels entre les Iraniens de la diaspora impériale, les Grecs et les populations locales de ces régions<br>The thesis studies the presence and influence of the Iranian peoples and tribes in the Pontus region from the origins to the fall of the Achaemenid Empire. While the sedentary Iranian people have been the center of attention, this work focuses firstly on the nomadic Iranian peoples originally living in western Siberia and who moved later in the north-Pontic region. In the absence of Cimmerian and Scythian written documents, the first part of thesis attempts to reconstruct a historical narrative of the migration and invasion of these people through the references made to them in ancient Greek and Assyrian texts, as well as by archaeological evidence. Modern debate about the Cimmerians’ linguistic and ethnic affiliation continues at a lively pace, for the existing documentation is both sparse and full of contradictions. Nonetheless, the inclination today is to consider them as an Iranian people. The second part of thesis traces the history of Scythian tribes in the North Pontic region. The first Scythian legend of origin, as related by Herodotus is studied and it is suggested that this legend incorporates typical features of Iranian legends of origin. The third part of the thesis studies the history of Pontus regions in the Achaemenid period and attempts to evaluate the impact of Persian and Iranian presence there. This part discusses the political status of the Pontus regions within the Achaemenid empire and attempts to determine the nature and the level of political incorporation of these regions into Achaemenid administrative organization. The work concludes by reviewing the written, archeological, artistic and various other sorts of evidence which suggests that there was not only a permanent presence of Persians and Iranians of the imperial diaspora, but also a considerable impact by the Achaemenid political and cultural influence in the Pontus region. This was due to the intense intercultural exchange between these Iranians and local populations

Dans les cités grecques, et particulièrement dans les systèmes démocratiques, l’exercice des magistratures amenait de nombreux citoyens à manier de l’argent public. L’oikonomos est l’une des magistratures financières civiques qui s’épanouit dans l’ensemble du monde grec à la fin de l’époque classique et pendant la période hellénistique, et plus précisément en Asie Mineure et dans les cités du Pont-Euxin.Le terme oikonomos renvoie à l’administration de l’oikos, l’unité économique et sociale de la société grecque. L’organisation de l’oikos et les pratiques déployées pour assurer la survie et le développement de ses membres, correspondent à des principes élémentaires connus depuis les poèmes épiques. À partir de la fin du Ve siècle, l’oikonomos est identifié comme détenteur d’une technè qui suscite les réflexions philosophiques dans la cité d’Athènes. Il est reconnu comme l’agent de la pratique de l’oikonomia, la science de la gestion domestique. À une époque de changements économiques, politiques et sociaux importants, les philosophes et les prosateurs font le lien entre la gestion domestique et l’administration des affaires de la cité. Grâce à l’apport des sources littéraires, notre enquête permet d’identifier et de comprendre le passage qui s’effectue à la fin du IVe siècle entre l’oikonomos, gestionnaire de l’oikos et la magistrature civique. Dans un second temps, l’étude des sources épigraphiques met en lumière le rôle et la place de la magistrature dans les cités où elle est attestée. Le plus souvent magistrat unique, l’oikonomos intervient à la fois dans le règlement des dépenses et dans la prise en charge matérielle des honneurs décrétés par la cité. Néanmoins, il n’est pas le seul magistrat. Trésoriers, néôpes ou d’autres magistratures, financières ou non, ont des rapports étroits avec l’oikonomos. L’analyse de leurs relations apporte des éléments de compréhension à la fois sur les attributions des oikonomoi, sur la chaîne des responsabilités engagées dans le processus de publication et de résolution des honneurs et enfin sur la gestion des finances des cités<br>In Greek cities, and especially in democratic systems, many citizens had to deal with public money. The oikonomos is one of the civic financial magistracies that spread throughout the Greek world in classical and Hellenistic times but especially in Asia Minor and Pont-Euxin.Firstly, the oikonomos refers to the administration of the oikos, the economic and social unit of Greek society. The organisation of the oikos and the practices implemented to ensure the survival and development of its members correspond to elementary principles known since epic poems. From the end of the 5th century onwards, the oikonomos has been identified as the holder of a technè that stimulated philosophical reflection in the city of Athens. The oikonomos was identified as the agent of the practice of oikonomia, the science of domestic management. In an era of significant economic, political and social change, philosophers established the link between domestic management and the administration of the city's affairs. The analysis of literary sources has made it possible to identify and understand the transition that took place at the end of the 4th century between the oikonomos, the manager of the oikos, and the civic magistracy. Secondly, the study of epigraphic sources highlights the role and place of the oikonomos in the cities where it is documented. In most cases, there was only one holder of the magistracy. The oikonomos was involved both in the payment of expenses and in the material support for the honours decreed by the city. Sometimes it may has been associated with other people. Treasurers, neopes or other financial or non-financial magistrates worked with the oikonomos. The analysis of their relationships provides elements for understanding not only the attributions of oikonomoi, the chain of the responsibilities involved in the process of honours publication and resolution but also on the management of the cities' finances