Along-strike variability of forced regressive deposits: late Quaternary, northern Peloponnesos, Greece

Abstract

AbstractLate 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.