--> Abstract: Structure and Facies Development of the Dutch/North German Rotliegende Basin, by P. Gralla; #90990 (1993).

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GRALLA, PETER, Veba Oil, Gelsenkirchen, Germany

ABSTRACT: Structure and Facies Development of the Dutch/North German Rotliegende Basin

The apparent east-west extension of the southern Rotliegende basin, stretching from southern England via the Netherlands and north Germany to Poland, developed from several subbasins running in a northwest-southeast direction.

The orientation of the subbasins and the graben systems have largely been caused by a regional stress field, which existed in the Late Paleozic of northern central Europe. The maximum extension was in an east-west direction. The graben systems of northern Germany and the southern part of the North Sea are running roughly north-south and are connected via a parallel set of wrench faults.

The subbasin with the largest Rotliegende thickness lies in the German part of the North Sea. It subsided in the region where the rift axis of the north-south-running north German graben system experienced left lateral displacements by northwest-southeast-running wrench faults. The active graben zone extended into the Horn-Bamle-Oslo graben.

The initial Dutch subbasin was connected with the early central graben and merged with the north German subbasin in the course of the progressive sedimentation of the basin. In contrast to the north German subbasin, where the initial sedimentation was mainly determined by the north-south-directed graben tectonics, intensive northwest-southeast-directed step faults developed in the Dutch subbasin.

The British subbasin was only marginally influenced by the active rift tectonics and is characterized by its comparatively low subsidence and/or sedimentation rates.

The initial subbasins were arranged in an en echelon pattern and merged during the main subsidence of the basin. The origin of the subbasins is linked to the Stephanian basins. Their development continued while several climate changes occurred up to the early Mesozoic.

Based on the multitude of exploration wells in the extensively explored British, Dutch, and German subbasins, the complex relationship between the post-Variscian tectonic processes and the cyclic climatic changes in the Rotliegende sediments can be recognized.

The influence of the climatic cycles on the Rotliegende sedimentation gets stronger toward the late stage of basin development, when subsidence was relatively reduced. The development of the intracontinental sedimentation from the small initial subbasin to the widespread southern Rotliegende basin can therefore be divided into three main stages: initial stage -- tectonics more effective than climate cycles, main stage -- equal effect of tectonics and climate cycles, and late stage -- climate cycles more effective than tectonics.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.