Pliocene and Lower Pleistocene fluvial history of the Lower Rhine Embayment, Germany: Examples of the tectonic forcing of river courses

Abstract

The Plio–Pleistocene succession has been studied in the northwestern and southern Lower Rhine Embayment by means of (a.o.) petrographical, geochemical and palaeomagnetic methods. Data obtained provide improved insight into the drainage pattern of the study area and give evidence to tectonically driven shifts of river courses. In the northwestern part of the region, the river Rhine changed its course gradually towards the north during Late Pliocene and Lower Pleistocene times. These shifts were forced by an increase of subsidence rates in the same direction. In the southern Lower Rhine Embayment, an infilling of the main channel of the Latest Pliocene Rhine river, the latter of which is represented by the newly defined “Öbel beds” throughout the Lower Rhine Embayment, was found in the central part of the tectonic unit of the Erft block (open-cast mine Hambach). Due to subsequent eastward tilting of this tectonic unit, the course of the Rhine shifted into the same direction. New palaeomagnetic results concerning the position of the Gauss–Matuyama boundary at the open-cast mine Hambach support this concept. A geochemical study of fine grained sediments has given evidence to a similar eastward shift of a local river entering the Lower Rhine Embayment from the south during Late Pliocene times. The Meuse river entered the Lower Rhine Embayment from the southwest during Pliocene times (“East Meuse river”). Probably, this course prevailed longer during the Early Pleistocene than previously thought. The advance of this river towards the east during Early Pleistocene times is probably due to the eastward tilting of the Erft block as well.