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How and when sediment moves from terrestrial sources to deep-water sinks is a significant area of research. We have used an array of seismic, borehole, and gravity core data sets to explore the timing and magnitude of sediment-routing to Pearl River slope over the last 478 k.y. As predicted by existing sequence stratigraphic models, most sediment dispersal to deep water is shown to have occurred during glacial sea-level falls; however, clastic detritus was still being transported into deep water during interglacial sea-level rises. We suggest that sediment routing to deep water during interglacial sea-level rise is caused by summer monsoon strengthening and resultant warmer and wetter climates, both of which have enhanced effective precipitation and sediment supply. Although some models for the delivery of sediment to deep-water basins stress the importance of proximity of canyon heads and coeval shorelines, we observed that sediment routing to deep water could occur regardless of the distance between channel head and coeval shorelines. In the present case, the success of delivery is related to the combined effects of (1) the short duration and high amplitude of sea-level oscillations during the past 478 k.y. and (2) the enhanced sediment supply caused by more humid climates and greater temperature difference between glacial and interglacial period. This hypothesis is supported by (1) observations that outer Pearl River deltas prograded as an apron over preexisting shelf edges for 10-15 km (6-9 mi) and (2) the occurrence of slope channels extending back to prodelta reaches of Pearl River shelf-edge deltas. [ABSTRACT FROM AUTHOR]

Using a seismic database from the Qiongdongnan Basin in the South China Sea, this study demonstrates that shelf-edge trajectories and stratal stacking patterns are reliable, but understated, predictors of deep-water sedimentation styles and volumes of deep-water sand deposits, assisting greatly in locating sand-rich environments and in developing a more predictive and dynamic stratigraphy. Three main types of shelf-edge trajectories and their associated stratal stacking patterns were recognized: (1) flat to slightly falling trajectories with negative trajectory angles (Tse) (-2° to 0°) and negative shelf-edge aggradation to progradation ratios (dy/dx) (-0.04 to 0) and associated progradational and downstepping stacking patterns with low clinoform relief (Rc) (150-550 m [492-1804 ft]) and negative differential sedimentation on the shelf and basin (As/Ab) (-0.6 to 0); (2) slightly rising trajectories with moderate Tse (0°-2°) and medium dy/dx (0- 0.04), and associated progradational and aggradational stacking patterns with intermediate Rc (250-400 m [820-1312 ft]) and intermediate As/Ab (0-0.6); and (3) steeply rising trajectories with high Tse (2°-6°) and high dy/dx (0.04-0.10) and associated dominantly aggradational stacking patterns with high Rc (350-650 m [1148-2132 ft]) and high As/Ab (1-2). Each trajectory regime represents a specific stratal stacking patterns, providing new tools to define a model-independent methodology for sequence stratigraphy. Flat to slightly falling shelf-edge trajectories and progradational and downstepping stacking patterns are empirically related to large-scale, sand-rich gravity flows and associated bigger and thicker sand-rich submarine fan systems. Slightly rising shelf-edge trajectories and progradational and aggradational stacking patterns are associated with mixed sand/mud gravity flows and moderatescale slope-sand deposits. Steeply rising shelf-edge trajectories and dominantly aggradational stacking patterns are fronted by large-scale mass-wasting processes and associated areally extensive mass-transport systems. Therefore, given a constant sediment supply, then Tse, dy/dx, Rc, and As/ A b are all proportional to intensity of mass-wasting processes and to amounts of mass-transport deposits, and are inversely proportional to the intensity of sand-rich gravity flows and to amounts of deep-water sandstone. These relationships can be employed to relate quantitative characteristics of shelf-edge trajectories and stratal stacking patterns to deep-water sedimentation styles. [ABSTRACT FROM AUTHOR]

A 300-km (186-mi) transect was reconstructed across the 500-m (1640-ft)-thick, 3-m.y. duration lies clastic wedge in southern Wyoming and northern Colorado using well logs and stratigraphic columns. This wedge developed into the middle-late Campanian-aged Western Interior seaway by progradation from the active Sevier fold and thrust belt and adjacent up-lifted areas. The wedge thickens basinward because late-stage, widespread uplift of the fold belt caused multiple unconformities across the proximal (former foredeep) reaches of the foreland basin. Transect analysis allows the wedge and its component sequences to be better understood and permits a two-dimensional characterization of the sand and mud distribution. The Iles wedge exhibits 11 low-gradient, regressive-transgressive, high-frequency sequences that were correlated across several hundred kilometers. Sediment partitioning analysis along the transect shows the following. (1) Within the regressive limb of the lies wedge, the component higher order regressive compartments tend to thicken into the medial reaches of the wedge, whereas transgressive compartments thicken landward. This geometry is driven by preferential erosion in proximal areas during regression, bypassing much sediment to the marine shorelines, and transgressive backfilling into proximal areas previously eroded more deeply. (2) The greatest concentration of sands tends to be located in the proximal fluvial and estuarine facies of the transgressive compartments and within the medial (shoreline) deltaic facies of the regressive compartments. (3) As the high-frequency sequences develop, the effectiveness of basinward sand partitioning reaches a maximum value near the peak regression level of the wedge, apparently reflecting stronger erosion and sediment bypass during these times. [ABSTRACT FROM AUTHOR]