A backstepping, fluviatile-paralic-marine succession, Sinemurian, Lower Jurassic, Skåne, southern Sweden

Abstract

A temporal exposure of a Lower Sinemurian succession of fluviatile, coastal plain and marine sediments was accessible for study during a short time interval in 1997 at Örby, NW Skåne, Sweden. The succession adds significantly to the knowledge and understanding of the Sinemurian sedimentary evolution of the Fennoscandian Border Zone and the north-eastern margin of the Danish Basin. The top of the section overlaps the base of a section previously exposed at the nearby quarry at Gantofta. The combined evidence from Örby, Gantofta and a few borings shows that Sinemurian sedimentation took place during marked stepwise transgression. This is recorded by backstepping of the depositional environments from braided streams, over lakes and swamps, to estuarine and finally fully marine, offshore conditions. The sedimentary packages of the individual systems are well defined and separated mainly by sharp boundaries representing lacustrine, estuarine and marine flooding and ravinement surfaces. A regional sea-level rise punctuated by a minor fall is suggested to be the main factor controlling Early Jurassic basin evolution of the northeastern margin of the Danish Basin and the Fennoscandian Border Zone.