This dissertation focuses on understanding the relative importance of external (eustacy) versus local tectonic and sedimentary processes in controlling continental-margin depositional architectures and their implications for sediment distribution. The emphasis of this study is the interpretation of clinoform geometries and stratigraphic relationships observed on 3D and 2D seismic reflection data in the Taranaki Basin, which is characterized by a variety of clinoform architectures on its Pliocene-Recent margin (Giant Foresets Formation). I combined seismic stratigraphic interpretations and biostratigraphic studies using a dataset that consists of 1,700 km2 of 3D seismic lines, 4,000 km of 2D regional seismic lines, and data from six wells. The study was divided into three sections. First, three major stages of clinoform evolution were identified based on their architectural and geomorphological characteristics. Isochron maps were generated to identify correlations between stratigraphy and paleostructures, and seismic attribute maps were elaborated to identify and characterize geological features and depositional elements. In the second phase of the study, 2D stratigraphic forward modeling techniques were applied in an effort to quantitatively determine the relative importance of the mechanisms acting in the basin (eustacy, tectonism and sediment supply). Finally, a similar approach was applied using clinoform morphologies in the eastern Trinidad margin where the tectonic configuration of the basin was completely different to the one in the Taranaki Basin. The objective was to compare the results in a region with different a tectonic setting to validate the applicability of the methodology in other basins worldwide. The results of this research indicate that the methodology that was developed for the quantitative analysis of clinoform architectures in the Taranaki Basin is applicable to other basins worldwide and that the work flow provides a more comprehensive understanding of the factors that influence continental margin development. Generic observations of this research showed that (1) underlying structures in the shelf and slope area can play an important role in influencing the location and morphology of the shelf edge area and controlling sediment distribution; (2) high sediment supply, along with accommodation, play a key role in the construction of high-relief clinoforms and earlier dispersal of sediments into deep water; and (3) lateral variations associated with high sediment discharge sources (e.g. paleo Orinoco shelf-edge delta) can generate important changes in continental-scale clinoform architectures alongstrike in continental margins influence sediment distribution patterns in the deep-water component of the basin. / text

Ce manuscrit de thèse propose la première étude sédimentologique exhaustive de l’escarpement du Dur At Talah (150 km de long sur 120 m de hauteur). Ce dernier affleure dans la dépression d’Abu Tumayam, dans la partie méridionale du Bassin de Syrte (Libye). La Formation du Dur At Talah offre une séquence sédimentaire régressive (au 2nd ordre), allant de faciès marins peu profonds à des faciès fluviatiles, datée de l’Eocène supérieur. Les exceptionnelles conditions d'affleurement ont permis une analyse sédimentologique approfondie (lithofaciès, ichnofaciès, géométries et découpage séquentiel) conduisant à une caractérisation multiscalaire d'un système margino-littoral dominé par la dynamique tidale. Parmi les résultats saillants de cette étude figure l'identification de deux processus sédimentaires : la progradation signée par des structures clinoformes et l’accrétion latérale caractérisée par des stratifications hétérolithiques inclinées (IHS). Dès lors, plusieurs corps sédimentaires se distinguent sans ambiguïté tel que les barres d’embouchure hétérolithiques et les barres de méandres de chenaux tidaux. L'auscultation de ces grands corps sédimentaires permet alors d'en définir les critères de reconnaissance et le contexte séquentiel de mise en place, mais aussi d'en contraindre le potentiel réservoir. / This manuscript provides the first exhaustive sedimentological study of the Dur At Talah escarpment (≈120 m high and ≈150 km length). This latter is exposed in the Abu Tumayam Trough, in the southern Sirt Basin (Libya). The Dur At Talah Formation forms a 2nd order regressive sequence, from shallow marine to fluviatile deposits, dated as upper Eocene. This exceptional outcrop allows an extensive and detailed sedimentological analysis (lithofaciès, ichnofaciès, geometries and sequence stratigraphy) leading to a multi-scale characterization of nearshore to paralic environments dominated by tidal dynamic. Among outstanding results, two sedimentary processes have been recognized and characterized: the progradation is expressed by large-scale clinoform structures and the lateral accretion is characterized by inclined heterolithic stratifications (IHS). Several sedimentary bodies are, thus, unequivocally distinguishable such as heterolithic mouth-bars and tidal channel point-bars. Thorough analysis of these sedimentary bodies allows to define diagnostic criteria to recognize them. They can be replaced in a consistent stratigraphic framework explaining their architecture and their vertical evolution in order to be used as reservoir analog.