‘Transgressive washing’ concept: a sequence stratigraphic approach for calci- and siliciclastic turbidites

Abstract

AbstractCarbonate breccias, calciturbidites and sandstone flysch sediments are typically assigned to the lowstand regime, based on the double assumption that these thick sedimentary packages necessitate (1) emergence phases for the production of their terrigenous material, and (2) a relatively lower position of the shoreline, which did not lie too far from the shelf-break line. In strictly regarding these conditions, we can run the risk of neglecting the role played by the transgression-related currents in reworking and exporting basinward bioclastic and siliciclastic sands from shelves. The ‘transgressive washing’ concept proposed here accounts for the latter mechanism, particularly in the case when the stratigraphic record shows that the onset of both the calci- and siliciclastic material was contemporaneous with newly marine-encroached continental source areas. Four examples from the Rifian internal (source) and external zones (basin) are presented to illustrate this phenomenon.