1999
Een analyse van bodembewegingen tijdens het Tertiair ten noorden van Winterswijk (Provincie Gelderland, Nederland)
Publication
Publication
Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie , Volume 36 - Issue 1/4 p. 109- 132
An experimental analysis of Cenozoic tectonic movements in an area north of Winterswijk (province of Gelderland) is presented. Based on a detailed lithostratigraphic framework which, within the area, enables correlations to be carried out on a scale of less than 1 metre, unconformities were traced. Their position in relation to NAP (Normaal Amsterdams Peil) was subsequently plotted on maps for each level; these maps form the basis of the analysis. Research into the deep subsoil (mineral exploration) and regular geological mapping of the shallow subsoil have not yielded corresponding results; to bridge this gap is the goal of the present investigation. To analyse tectonic structures numerous boreholes are needed; data assembled from wells sunken for private people in the area have shown that the results are spectacular and fundamental. The study area lies on the border of the Münsterland Basin, a subsidence area during the Cretaceous, and the North Sea Basin, which is a Cenozoic subsidence area. In this region compressional movements occurred during the Late Cretaceous and Early Cenozoic, tilting and resulting angular unconformities in several intervals of short duration during the entire Cenozoic, and decompression in two phases, widely separated in time, during the early Late Cenozoic and, probably, continuing into the Pleistocene. Remarkable at the Eocene-Oligocene transition are strong inversion movements, as a result of compression (Pyrenean phase ?). In the Late Rupelian (transition Woold and Winterswijk members), locally also a comparable movement is found, but this may be due to local salt tectonics. Of note also is the outcome of tension, the subsidence of narrow zones along existing faults, which occurred in two widely separated intervals (at least 20 Ma apart). The influence of this so-called Savic phase is found to predate sedimentation of the Aalten Member, and is possibly of Early Miocene date. A second phase has been recognised after deposition of Miocene (and Early Pliocene) deposits, and may probably be dated as Pleistocene. In the present paper, the existing tectonic orogenesis and the results obtained here are not linked, since these are ambiguous. The importance of a very detailed lithostratigraphy is demonstrated; boreholes were sampled either continuously (core) or every 25 cm (cuttings); in samples taken every 50 cm the overall picture may still be recognised. However, in 1 m samples it is blurred to such an extent that such samples are not suitable for detailed tectonic analyses. In part, this explains why the Cenozoic interval is so poorly known in exploration wells in the area.
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Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie | |
CC BY-NC-ND 2.0 NL ("Naamsvermelding-NietCommercieel-GeenAfgeleideWerken") | |
Organisation | Werkgroep voor Tertiaire en Kwartaire Geologie |
Maarten van den Bosch. (1999). Een analyse van bodembewegingen tijdens het Tertiair ten noorden van Winterswijk (Provincie Gelderland, Nederland). Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie, 36(1/4), 109–132. |