Spatial-Temporal Evolution from Meandering to Sinuous Deep-Water Channels: Examples from the Tachrift Turbidite System (Taza–Guercif Basin, NE Morocco, Late Tortonian)

Submarine channels are conduits for sediment and channel fills represent important reservoirs for natural resources and low-carbon initiatives. Although channel types are known, e.g., meandering, sinuous etc., the processes controlling changes from one style of channel to another remain elusive.

Here, the sedimentary architecture of a well-exposed channel-levee complex, of the Tachrift Turbidite System (late Tortonian, Melloulou Fm., Taza–Guercif Basin) is presented to investigate changes in channel style. Excellent lateral continuity (>2 km) and outcrop quality allowed acquisition and correlation of seventy-five sedimentary logs (at 1:20 scale). This dataset reveals the stratigraphy of the complex, which is subdivided into three units, representing different stages in the evolution of the complex. Unit 1 records the initial stage of the complex with tabular sandstone beds, with lateral accreting packages representing an eastward migration of a meandering channel. Unit 2 records a significant reorganization of the channel belt, with significant basal erosion and mass-wasting, followed by aggradation in the southeastern portion of the complex, and relocation of the channel-axis toward northwest. Finally, Unit 3 records eastward migrating channels in the upper part of the complex and represents the late phase fill until shutdown of the channel system.

This channel complex displays a peculiar evolution that differs from the classic evolutionary models, characterized by initial meandering channel fills, followed by a change to a sinuous system, before finishing with meandering channels. This example of atypical sedimentary architecture can help calibrate depositional models that can be used as an analogue for similar channel systems.