BOTTOM-CURRENT-CONTROLLED SEDIMENTATION - A SYNTHESIS OF THE CONTOURITE PROBLEM

An overview of the main items concerning deep bottom-current-controlled deposits is presented. These include: the definition of contourites, their processes of deposition and facies characteristics; contourite drift types and seismic patterns; the interplay of turbidity and bottom-current processes; and the correlation between bottom-current processes and global changes in climate/sea-level. From this discussion, several of the more significant problems are highlighted, which we believe should be priority targets for future research: (1) identification of contourites, especially in ancient series, where they are interbedded with turbidites and other facies; (2) refinement of the numerous parameters used as tracers of palaeocirculation patterns; (3) understanding the interaction between the different types of bottom currents, and also between bottom-current and other deep-water processes; (4) distinction in the sedimentary record between the effects of short time-scale bottom-current variations due to regional causes like benthic storms, and geological-scale current fluctuations related to climatic or astronomic control; (5) understanding the control of glacial/interglacial climatic cycles on the nature and rate of contourite deposition.