The tectonic evolution of the southern Dutch North Sea during the Palaeogene: basin inversion in distinct pulses

In this paper, we discuss the response of a sedimentary basin to compressional reactivation of extensional faults in distinct pulses. The inversion of the Broad Fourteens Basin in the southern Dutch North Sea is used as a case study. The first pulse of inversion occurred during the Late Mesozoic as a result of the sub-Hercynean phase. A second pulse occurred during the Mid-Palaeocene Laramide phase. A final inversion pulse occurred around the Eocene-Oligocene boundary coinciding with the Pyrenean tectonic event. We reconstructed the stratigraphic and structural development of the area during the Palaeogene in detail. Basic data are two 2D-seismic surveys, supported by 74 geophysical wireline logs, on which newly constructed depth and thickness maps are based. The reconstruction is aided by a quantitative subsidence analysis. Cessation of compression resulted in relaxation and tensional reactivation of faults caused differential subsidence. Inheritance of geological structures is a key element in the tectonic activity in the Broad Fourteens Basin during the Palaeogene; tectonic movement during the Palaeogene was always accommodated by reactivation of Palaeozoic-Mesozoic faults. The intensity of inversion in the southern North Sea Basin during the Pyrenean phase appears much larger than previously noticed. Moreover, the area affected by the inversion is much wider than during previous phases. Minor differences in the direction of the local stress field between the tectonic phases and by the deposition of a thick sedimentary succession during the periods of tectonic quiescence between the inversion phases can account for this. (C) 2003 Elsevier B.V. All rights reserved.