STRUCTURAL EVOLUTION OF THE GERMAN CENTRAL GRABEN

In former studies of the German North Sea sector (Baldschuhn et al., 2001) the northwestern part of the German North Sea sector, the so called „Entenschnabel“ is missing. Therefore a detailed structural model of the area is developed within the framework of the GPDN-Project (Geopotenzial Deutsche Nordsee). The model is based on detailed interpretation of seismic and well data. The focus of the presented work is on the structural and kinematic evolution from the Rotliegend to the Paleogene in the “Entenschnabel” and surrounding areas. In addition to fault interpretation and structural analyses our studies include the investigation of salt structures, their evolution and interaction with the predominant fault-pattern.

In the Entenschnabel area, the Central Graben is the dominating structural element. First extensional pulses took place in the Lower Triassic followed by several phases of rifting from the Middle to Late Triassic. During the Jurassic the main extensional phase took place in combination with extensive diapirism. In the major grabens further to the east (Horn Graben, Glückstadt Graben), a Jurassic extensional event is absent or less evident. Due to this differences in evolution history most of the Upper Jurassic sediments are preserved inside the Central Graben. Analyses of rim-synclines reveal that most of the salt structures inside the Central Graben had a main phase of growth during the Late Jurassic while the salt structures situated toward the southeast had their main phase of growth during the Triassic.

Another difference of the German Central Graben compared to the rest of the German North Sea is a structural inversion during the Late Cretaceous. Most of these Late Cretaceous inversion structures along the Central Graben indicate an approximate E-W component of contraction which is nearly perpendicular to the regional trend of contraction along the Central European Basin System in a NE-SW to NNE-SSW direction during this time.

Baldschuhn, R., et al. (2001). Geotektonischer Atlas von Nordwestdeutschland und dem deutschen Nordsee-Sektor - Strukturen, Strukturentwicklung, Paläogeographie. Geologisches Jahrbuch, A 153: 3-95.