--> Abstract: Fan Delta of the Middle Devonian "Granite Wash" and Keg River Clastics, Red Earth Field, North Alberta Basin, Canada, by H. Sabry; #91012 (1992).

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ABSTRACT: Fan Delta of the Middle Devonian "Granite Wash" and Keg River Clastics, Red Earth Field, North Alberta Basin, Canada

SABRY, HASSAN, Mobil Oil Canada

A detailed sedimentological investigation of over 4000 ft of core and 500 well logs of the Middle Devonian "Granite Wash" and Keg River clastics in the Red Earth field, North Alberta basin, Canada, has led to the recognition of a "Granite Wash" subaerial fan-delta that is laterally continuous with a Keg River subaqueous delta component along an eastern shoreline of the ancestral Peace River Arch.

The subaerial fan-delta includes these lithofacies: (1) alluvial fan facies, (2) sheet wash and mud flows, and (3) playa lakes. The subaqueous delta component includes these lithofacies: (1) lower shoreface, (2) upper shoreface, (3) beach-foreshore, (4) eolian sand dunes, (5) lagoon, (6) washover sands, (7) tidal channels and flats, and (8) supratidal carbonates and anhydrites. Within this system, six mappable units are defined. These are in ascending order: (1) Granite Wash A sand, (2) Granite Wash B sand members, (3) Granite Wash shale member, (4) Keg River A, (5) Keg River B, and (6) Keg River C members.

A conceptual depositional model for the sequence depicts four main events:

1. Erosion of Peace River arch uplifted faulted blocks produced coarse-grained fan-delta sediments in adjacent fault-bounded margin. Subsequent fluvial reworking resulted in the deposition of thick lenticular and wedge-shaped alluvial fans of Granite Wash.
2. Progradation of alluvial fans seaward tectonically triggered into the Keg River Sea.
3. Transgression by Middle Devonian seas from the east reworked alluvial fans and led to deposition of discontinuous linear sand bodies represented by the landward (backstepping) migration of Keg River shoreline sediments westward.
4. Restriction of the sea by the Presquil'le Barrier Reef to the north deposited evaporites of the Muskeg Formation over the whole sequence.

A modern analog to this fan-delta system is the coastal fans, Gulf of Aqaba, Red Sea. Red Earth field contains over 27 million barrels of recoverable oil, related to a combination structure-stratigraphic trap.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)