Early Eocene successions from Spitsbergen and o¡shore Ireland, showing well-developed shelfmargin clinoforms and a variety of deepwater sands, are used to develop models to predict the presence or absence of turbidite sands in clinoform strata without signi¢cant slope disturbance/ ponding by salt or mud diapers.The studied clinoforms formed in front of narrow to moderate width (10^60 km) shelves and have slopes, 2^41, that are typical of accreting shelf margins.The clinoforms are evaluated in terms of both shelf-transiting sediment-delivery systems and the resultant partitioning of the sand and mud budget along their di¡erent segments. Although this sedimentbudget partitioning is controlled by sediment type and £ux, shelf width and gradient, process regime on the shelf and relative sea-level behaviour, the most tell-tale or predictive signs in the stratigraphic record appear to be (1) sediment-delivery system type, (2) degree of shelf-edge channelling and (3) character of shelf-edge trajectory through time.The clinoform data sets from the Porcupine Basin (wells and 3-D seismic) and from the Central Basin on Spitsbergen (outcrops) suggest that riverdominated deltas are the most e⁄cient delivery systems for dispersing sand into deep water beyond the shelf-slope break. In addition, low-angle or £at, channelled shelf-edge trajectories associate with co -eval deepwater slope and basin-£oor sands, whereas rising trajectories tend to associate with muddy slopes and basin £oors. Characteristic features of the shelf-edge, slope and basin-£oor segments of clinoforms for these trajectory types are documented. Seismic lines along the slope to basin-£oor transects tend to show apparent up-dip sandstone pinchouts, but most of these are likely to be simply sidelap features. Dip lines aligned along the axes of sandy fairways show that stratigraphic traps are unlikely, unless slope channels become mud-¢lled or are structurally partitioned. Another feature that is prominent in the data sets examined is the lack of slope onlap. During the relative rise of sea level back up to the shelf, the clinoform slopes are generally mud-prone and they are characteristically aggradational.
The down-dip portion of submarine fans comprises terminal lobes that consist of various gravity flow deposits, including turbidites and debrites. Within lobe complexes, lobe deposition commonly takes place in topographic lows created between previous lobes, resulting in an architecture characterized by compensational stacking. However, in some deep water turbidite systems, compensational stacking is less prominent and progradation dominates over aggradation and lateral stacking. Combined outcrop and subsurface data from the Eocene Central Basin of Spitsbergen provide a rare example of submarine fans that comprise progradationally stacked lobes and lobe complexes. Evidence for progradation includes basinward offset stacking of successive lobe complexes, a vertical change from distal to proximal lobe environments as recorded by an upward increase in bed amalgamation, and coarsening and thickening upward trends within the lobes. Slope clinoforms occur immediately above the lobe complexes, suggesting that a shelfslope system prograded across the basin in concert with deposition of the lobe complexes. Erosive channels are present in proximal axial lobe settings, whereas shallow channels, scours and terminal lobes dominate further basinward. Terminal lobes are classified as amalgamated, non-amalgamated or thin-bedded, consistent with turbidite deposition in lobe axis, offaxis and fringe settings, respectively. Co-genetic turbidite-debrite beds, interpreted as being deposited from hybrid sediment gravity flows which consisted of both turbulent and laminar flow phases, occur frequently in lobe off-axis to fringe settings, and are rare and poorly developed in channels and axial lobe environments. This indicates bypass of the laminar flow phase in proximal settings, and deposition in relative distal unconfined settings. Palaeocurrent data indicate sediment dispersal mainly towards the east, and is consistent with slope and lobe complex progradation perpendicular to the NNW-SSE trending basin margin.
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