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The Eocene-Oligocene Annot Sandstones of southeast France record the predominantly deep-water, siliciclastic infill of the early French Alpine foreland basin. They accumulated in a topographically complex basin as recorded by variable onlap relationships with the underlying Globigerina Marls. Onlap configurations and paleobathymetric data from the western outcrops of the Annot Sandstones enables a contour map of the pre-Annot Sandstone basin-floor topography to be reconstructed. The basin comprised a northern and a southern sub-basin, which were separated by a ridge, through which a trough was cut (the Coyer Trough) linking the two sub-basins during the latter stages of infilling. Data on provenance and paleocurrents suggest that the sandstones were sourced from two main feeder systems: an eastern source from the Alps fed the northern sub-basin, and a southern source fed the southern sub-basin. There is evidence of mixing of provenance in the lower parts of the southern sub-basin.Integration of the reconstructed basin-floor topography, sedimentdispersal data, and facies and stratal architectures suggests a depositional model comprising sand-rich, delta-fed submarine ramps and/or aprons whose development was strongly influenced by the basin-floor topography. The southern sub-basin initially had a steeper delta front, characterized by debris flows; this contrasted with the lower-gradient northern sub-basin. The southern sub-basin comprises approximately 800 m of thick-bedded sandstones interpreted as the deposits of sustained and possibly ponded turbidity currents. The upper part of the southern sub-basin records increased channeling and scour related to bypass of material after the basin was filled; these channels transported material northwards through the Coyer Trough, and capped the northern sub-basin. This development of the southern sub-basin is comparable to the ''fill and spill'' development of perched, intra-slope basins in the Gulf of Mexico.
The Eocene-Oligocene Annot Sandstones of southeast France record the predominantly deep-water, siliciclastic infill of the early French Alpine foreland basin. They accumulated in a topographically complex basin as recorded by variable onlap relationships with the underlying Globigerina Marls. Onlap configurations and paleobathymetric data from the western outcrops of the Annot Sandstones enables a contour map of the pre-Annot Sandstone basin-floor topography to be reconstructed. The basin comprised a northern and a southern sub-basin, which were separated by a ridge, through which a trough was cut (the Coyer Trough) linking the two sub-basins during the latter stages of infilling. Data on provenance and paleocurrents suggest that the sandstones were sourced from two main feeder systems: an eastern source from the Alps fed the northern sub-basin, and a southern source fed the southern sub-basin. There is evidence of mixing of provenance in the lower parts of the southern sub-basin.Integration of the reconstructed basin-floor topography, sedimentdispersal data, and facies and stratal architectures suggests a depositional model comprising sand-rich, delta-fed submarine ramps and/or aprons whose development was strongly influenced by the basin-floor topography. The southern sub-basin initially had a steeper delta front, characterized by debris flows; this contrasted with the lower-gradient northern sub-basin. The southern sub-basin comprises approximately 800 m of thick-bedded sandstones interpreted as the deposits of sustained and possibly ponded turbidity currents. The upper part of the southern sub-basin records increased channeling and scour related to bypass of material after the basin was filled; these channels transported material northwards through the Coyer Trough, and capped the northern sub-basin. This development of the southern sub-basin is comparable to the ''fill and spill'' development of perched, intra-slope basins in the Gulf of Mexico.
The Eocene to Oligocene deposits of the Alpine Foreland Basin of Southeast France include a series of partially preserved, originally interconnected turbidite-filled subbasins. Within these remnants, well-constrained interpretations of sediment architectures have been developed by many geologists of the last five decades which are used to resolve both intrabasinal and interbasinal filling histories (e.g., the Annot, Grand Coyer, Col de la Cayolle, and Trois É vêchés subbasins). However, little is known about the depositional system in more distal areas. The Eastern Grès du Champsaur (Champsaur Sandstones), which has not been subject to detailed evaluation, is thought to represent the down-dip continuation of the Grès d'Annot Turbidite System. Presented here is an outcrop case study from the Eastern Champsaur Basin that describes how intrabasinal bathymetry affected gravity-current behavior, in turn driving quantifiable variations in sediment distribution patterns.The initial paleobathymetric template of the Eastern Champsaur Basin prior to turbidite deposition is reconstructed here through the generation of isopach maps constructed from field studies of the basin fill. The extent to which successive onlapping turbidity-current deposits were controlled by this bathymetry is determined through the analysis of paleocurrent, facies proportion, and isopach data from measured sections. Quantifiable variations in both facies (particularly the occurrence of clast-rich intervals) and sand/shale ratio are observed in association with an intrabasinal high, which is interpreted to have contained flows within this depositional system, allowing only a relatively finer fraction of the flow to move down dip in the distal parts of the basin. This study has direct application in aiding the understanding of sand emplacement processes at the fringes of turbidite basins, in defining the genesis of stratigraphic trap geometries in confined deep-water settings, and in better understanding connectivity issues within deep-water reservoirs.
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