Channel development in the chalk of the Tor Formation, North Sea: evidence of bottom current activity - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 575

Phase 1: Incision of the sea floor and channel margin aggradation

Upslope bottom current
from the deep part of the
Central Graben

N

Incipient Ekofisk and
West Ekofisk highs

Headward retreat
by collapse of the
channel margin

A '

A

Channel margins

A A '

2km

Phase 2: Passive infilling by allochthonous chalk material

Incipient Ekofisk and
West Ekofisk highs

A '

Down slope
mass
movements
deflected by
the current
toward SE

A

A A '

2 km

Fig. 16. Block-diagram cartoon showing the inferred two main phases of the channel development, corresponding to the
deposition of the lower and upper channel units. The bipartite subdivision of the Tor Formation with pelagic facies below
(BHC facies in Figs 14 and 15) and allochthonous material above (e.g. PFC and DC facies in Figs 14 and 15) represent
respectively the channel initial channel erosion and aggradation (Phase 1: channel development) and the subsequent infill
by gravity flow deposits (Phase 2: channel-fill).