Early Cretaceous turbidites of the Outer Moray Firth form a major hydrocarbon play in the early post-rift of the UK North Sea.

Rifting and subsequent sediment starvation during the late Jurassic resulted in the early Cretaceous inheriting a complex antecedent rift topography. Detailed seismic horizon mapping has identified the sub-division of the Outer Moray Firth into the westerly Witch Ground Basin and the easterly Renee Basin by an ‘Axial High'. Seismic analysis has also helped to constrain the sedimentation history of the early Cretaceous. The Axial High exerted considerable control on sedimentation during the earliest Cretaceous, but this diminished through time, and was subsequently breached allowing flows access to the Renee Basin. Horizon mapping has also identified the shifting and eastwards migration of the main depot-centres through the early Cretaceous. This is interpreted as the progradation of the depositional system.

Sediment gravity flows are interpreted to have transported sediment axially through the Outer Moray Firth. The depositional system exhibited a change from an confined depositional setting in the west to an unconfined nature in the east. The sediments deposited by these flows are ‘atypical' turbidites. Sedimentary structures within the cores indicate deposition by the full spectrum of sediment gravity flows, but dominantly by high density turbidity currents and slurry flows (flows transitional between debris flows and turbidity currents).

The major controls on sedimentation are; the antecedent topography, relative sea-level and provenance area.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah