Stratigraphic and lithologic relationships: lateral outcrop profiles and architectural elements of middle Eocene Torrey submarine canyon, La Jolla, California

Heterogeneous fills within similar subsurface systems are problematic for hydrocarbon exploration and production. Diagramming the stratigraphic and lithologic associations of the Torrey Canyon on photomosaics demonstrates the complexities. Many elements resemble fluvial fills; others are unique to the submarine setting. The basal (first-order) bounding surface is an unconformity, at least 2 mi wide, truncating paralic to slope units. Internally, the canyon comprises channels on a variety of scales. Large (second-order) cuts are up to 300 ft deep and 1/2 mi wide. Within these are (third-order) crosscutting, meandering to braided channels, 5 ft to more than 60 ft deep and 10 ft to more than 1500 ft wide. A variety of (fourth order) bed forms, lithofacies, and fabrics embody the fill. Conglomerates occur as bars, channels, and sheets. They range from clast to matrix supported and disorganized to imbricated. Sandstones include sheets with turbidite or dish structures; channels of structureless to faintly laminated crosscutting units; and crevasse-splay wedges, sheets, and channels of laminated, cross-bedded, or rippled fabrics. Fine-grained deposits are sheets or channel fills and encompass intercalated sandstone and mudstone, mudstone with starved ripples, and laminated mudstone. Lithologically diverse slump masses add further complexities. The predominance of conglomerates and interconnected sandstonesmore » downdip vs. mudstone channels and segregated sandstones updip provides a model for predicting subsurface reservoir types, geometries, and permeability trends in similar systems.« less