Late Cretaceous unconformities in the Subhercynian Cretaceous Basin (Germany)

Abstract

In the Subhercynian Cretaceous Basin, six Upper Cretaceous angular unconformities can be observed. The first unconformity, at the base of the Cenomanian transgressive deposits, is not related to the development of the basin. While the second (Lower to Middle Coniacian) unconformity is almost limited to the northern basin margin, four unconformities are developed at the Harznordrand Thrust and span the short period from the Middle Santonian to the late Early Campanian (about 3 Ma). The intra-Coniacian unconformity at the northern basin margin proves tilting of the basin floor to the south-east and is possibly related to the development of the thrust too. The Santonian to Campanian unconformities at the Harznordrand Thrust reflect the formation of a continuously growing fault-propagation fold. Deposition above unconformities occurred when the rate of eustatic sea-level rise exceeded thrusting rate. Transgressions occurred in the earliest Middle Santonian, in the Late Santonian (intra-Marsupites Zone), in the earliest Campanian (granulataquadrata Zone) and in the late Early Campanian (Offaster pilula Zone). The ages of unconformities correlate well with the transgressive pulses proved in Western and Middle Europe and are not related to discrete deformational events.