--> Abstract: Slump/Mass Flow Dominated Cretaceous Slope Facies, Northern North Sea and Norwegian Sea (61-67 degrees N), by G. Shanmugam, L. R. Lehtonen, T. Straume, S. E. Syvertsen, R. J. Hodgkinson, and M. Skibeli; #90987 (1993).

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SHANMUGAM, G., Mobil Research and Development Corporation, Dallas, TX; L. R. LEHTONEN, Mobil Exploration and Producing US, Dallas, TX; and T. STRAUME, S. E. SYVERTSEN, R. J. HODGKINSON, and M. SKIBELI, Mobil Exploration Norway Inc., Stavanger, Norway

ABSTRACT: Slump/Mass Flow Dominated Cretaceous Slope Facies, Northern North Sea and Norwegian Sea (61-67 degrees N)

A regional study of Cretaceous sequences, based on 500 m of core from 14 wells, in the mid-Norway and Agat areas revealed that these sequences were deposited in an upper continental slope environment by mass-transport processes. There are eight distinct lithofacies: Facies 1 (conglomerate and pebbly sandstone) represents deposits of sandy mass flows/slumps, possibly in a channel setting; Facies 2 (contorted sandstone) is the most widespread and is the product of sandy mass flows/slumps; Facies 3 (contorted mudstone) suggests deposition from muddy mass flows/slumps; Facies 4 (rippled sandstone) indicates bottom-current reworking; Facies 5 (graded sandstone) represents turbidity-current deposits and is very rare; Facies 6 (laminated mudstone) represents suspension settling; Facies 7 (cr ss-bedded sandstone) is indicative of tidal channel processes; and Facies 8 (laminated sandstone) represents delta-front deposits. These facies suggest an upper slope/shelf-edge delta environment of deposition. There is also an abundance of sandstone dikes and sills, which may be related to overpressuring and dilation of sands caused by slumping. Although seismic facies are not resolvable at the Agat core sites, mounded seismic facies do occur downslope within the same depositional sequence. Our model predicts that these mounds may be composed of slump/mass-flow deposits. A modern analogue is the Storegga Slide on the Norwegian continental margin. This model differs from the conventional submarine-fan model, which has previously been advocated for these sandstones, and implies different epositional processes, settings, and sand-body geometries than predicted by a fan model.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.