ABSTRACT

Detailed field and photogeological mapping of the Charo Canyon and Arro Sandbody, which can be traced directly into the canyon, shows the relationships between shelf, slope, canyon, and base-of-slope deposition. The Charo Canyon is incised into slope and shelf facies of the Castisent Group (50.5-49.5 Ma), and was a sediment conduit for turbidity currents and their deposits during the upper part of the Castisent Group, and the Santa Liestra Group (49.5-44 Ma). The Arro Sandbody, downslope from the Charo Canyon, belongs to the upper part of the Castisent Group. Unlike the overlying Santa Liestra channel complex, the Arro Sandbody, shows few features typical of a channel-fill deposit, but is characterized by a base-of-slope facies association in front of the canyon mouth. The key factors influencing the internal architecture of the Arro Sandbody were variations in slope angle and an increase in sediment supply, both factors being largely controlled by mid-Castisent thrust activity. This paper describes the composite fill of the Charo Canyon and investigates its relationship to the depositional setting of the downcanyon deposits.