SILICICLASTIC SLOPE AND BASE-OF-SLOPE DEPOSITIONAL SYSTEMS - COMPONENT FACIES, STRATIGRAPHIC ARCHITECTURE, AND CLASSIFICATION

Subaqueous slope and base-of-slope depositional systems are a major co mponent of most marine and many lacustrine basin fills, and constitute primary targets for hydrocarbon exploration and development. Seven ba sic facies building blocks comprise slope systems: (1) turbidite chann el fills, (2) turbidite lobes, (3) sheet turbidites, (4) slide, slump, and debris-flow sheets, lobes, and tongues, (5) fine-grained turbidit e fills and sheets, (6) contourite drifts, and (7) hemipelagic drapes and fills. The grain size of supplied sediment is a primary control on channel and lobe morphologies and on the scale and importance of slum p and debris-flow deposits. Two general families of siliciclastic slop e systems occur. Constructional (allochthonous) systems, including fan s, aprons, and basin-floor channels, are built of sediment supplied fr om superjacent delta, shore-zone, shelf, or glacial systems. The facie s architecture of allochthonous systems is determined jointly by the s ediment texture and pattern of supply to the shelf margin. Point sourc es of supply create fans; line sources create strike-elongate prisms o f slope sediment called slope aprons. Shelf-margin deltas provide a pa rticularly common intermediate source geometry, forming offlapping del ta-fed aprons. Autochthonous systems, including retrogressive aprons, canyon fills, and megaslump complexes, record slope reworking and rese dimentation.