SEDIMENTARY EXPRESSION AND GEODYNAMIC SIG NIFICANCE OF DEPOSITIONAL SEQUENCES IN A STABLE PLATFORM DOMAIN - EXAMPLE FROM THE HETTANGIAN IN THE GERMAN BASIN

Six depositional sequences (duration less than 1 Ma), probably of eust atic origin, have been identified in the German Basin during the Lower Lias. In the absence of regional unconformities, each unit was define d between two condensed sections correlatable at the basin scale. Duri ng the Hettangian, the stacking pattern of the depositional sequences characterizes a transgressive/regressive cycle. In the regressive part of this cycle, the vertical evolution of the more distal and proximal facies is perturbated. It leads to an ambiguity concerning the genera l tendency of eustatic variations. The perturbation can be interpreted as the sedimentary expression of changes in amplitude of the eustatic signal, which induces the depositional sequences of short duration.