Along-strike variability of forced regressive deposits: late Quaternary, northern Peloponnesos, Greece
Lesley S. McMurray, Robert L. Gawthorpe, 2000. "Along-strike variability of forced regressive deposits: late Quaternary, northern Peloponnesos, Greece", Sedimentary Responses to Forced Regressions, D. Hunt, R. L. Gawthorpe
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Late Quaternary depositional sequences in northern Peloponnesos, central Greece, occur as a number of offlapping and downstepping forced regressive wedges. Major along-strike variability is evident, with three environmental responses to forced regression: (i) attached shoreface deposits; (ii) detached shoreface deposits; (iii) fan-deltas. All three depositional systems are cut by incised valleys. Relative sea-level change was responsible for similarities in key stratal surfaces and stacking patterns; regional uplift drove the overall forced regression, whereas individual sequences relate to fourth- and fifth order glacioeustatic cycles. Variations in basin physiography and the amount and type of sediment led to along-strike variability of depositional sequences. Fan-deltas developed at the mouths of incised valleys in the west of the area, where supply of coarse-grained sediment was high and slope gradients were steep. In contrast, limited supply of coarse-grained sediment and low slope gradients over most of the study area promoted the development of shoreface systems. Forced regressive wedges in the shoreface systems attach and detach along strike. Detached wedges developed where both slope gradients and coarse-grained sediment supply were low, away from the axes of major incised valleys.
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Sedimentary Responses to Forced Regressions
An increasing number of studies in recent years have demonstrated that significant progradation of shallow marine systems occurs under conditions of base-level fall. These new data are forcing many sedimentary geologists to critically re-evaluate many aspects of sequence stratigraphy relating to erosion and deposition during base-level (lake- or relative sea-level) fall, and the intrinsic link made between stratal geometries and base-level change. For the first time, this volume brings together a collection of articles that focus solely on forced regressions, providing a more complete picture of the development, formation, variability and preservation of the surfaces and deposits generated during base-level fall.
The results of the studies published here will be of interest to all geologists attempting to understand the relationship between changes in base-level and stratigraphy, and to all who use sequence stratigraphy as a method of stratigraphic correlation and interpretation at outcrop and in the subsurface.