CARDIUM FORMATION AT RICINUS FIELD, ALBERTA: A CHANNEL CUT AND FILLED BY TURBIDITY CURRENTS IN CRETACEOUS WESTERN INTERIOR SEAWAY.

Ricinus field is different from all other Cardium fields: the sandstone body is up to 20 m thick compared with a Cardium average of only a few meters, and well-log cross sections indicate that this 20-m sandstone rests in a channel up to 55 km long, 8 km wide and 20-40 m deep. Study of 71 cores showed that the channel fill consists of massive sandstone beds up to several meters thick, and thinner graded beds that are either massive or contain the sequence of sedimentary structures from parallel lamination to ripple cross-lamination. The nature of the channel fill indicates deposition in depths mostly below storm wave base, probably by turbidity currents. The channel also may have been eroded by turbidity currents during a brief lowstand of sea level.