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A Revised Stratigraphy for the Pliocene and Lower Pleistocene Deposits of the Lower Rhine Embayment
Fluvial sedimentary record of the Rhine/Meuse system
H.A. Kemna
Journal: Netherlands Journal of Geosciences / Volume 87 / Issue 1 / March 2008
Published online by Cambridge University Press: 01 April 2016, pp. 91-105
The Plio-Pleistocene succession in the Lower Rhine Embayment was subjected to a thorough revision of existing stratigraphic concepts. The deposits were studied at key sites in the type area near Venlo and in the large open-cast mine Hambach in the southern part of the Lower Rhine Embayment by means of sedimentological, petrographical, as well as palaeo- and rockmagnetic methods.
The work has yielded improved insights of the drainage pattern and the Late Pliocene and Early Pleistocene depositional history of the region. As a result, a new comprehensive lithostratigraphical framework has been established.
Study of the succession at Hambach showed the occurrence of deposits of the Rhine, Meuse and a local river in the Lower Pleistocene part of the succession. Paleo- and rockmagnetic studies of the deposits marking the transition from Pliocene to Pleistocene indicate that the Gauss-Matuyama magnetic reversal occurs several meters above the top of the Reuver Clay at Hambach.
The study of the Lower Pleistocene succession in the type area has confirmed the recently new established lithostratigraphic framework of the Netherlands. As a consequence, the previous Dutch lithostratigraphic system which forms the basis of the chronostratigraphic subdivision of the Pliocene and Early Pleistocene of NW Europe has been proven to be inappropriate and should be abandoned. This chronostratigraphic framework is based on the interpretation of palynological data and was first established in the Netherlands during the 1960s. The new lithostratigraphic concept has revealed numerous contradictions with the chronostratigraphic framework. Based on these results it is proposed to abandon the chronostratigraphic subdivision of the Early Pleistocene in northwestern Europe.
The confluence area of Rhine, Meuse, and Belgian rivers: Late Pliocene and Early Pleistocene fluvial history of the northern Lower Rhine Embayment
W.E. Westerhoff, H.A. Kemna, W. Boenigk
Published online by Cambridge University Press: 01 April 2016, pp. 107-125
The fluvial history of the northern Lower Rhine Embayment shows interplay of three main river systems: Rhine, Meuse and smaller rivers draining the central and northern part of Belgium.
The Pliocene and Early Pleistocene (pre-)Rhine and Meuse river systems had their conjunction in the southern part of the Roer Valley Graben between Aachen and Jülich. Despite slight differences in the heavy-mineral assemblages the lithological composition of the Pliocene deposits of the three river systems shows close resemblance and therefore they cannot be mapped separately. However, due to a marked change of the petrographical composition the Upper Pliocene and Lower Pleistocene deposits of the Rhine are easily recognised and as a result Rhine and Meuse deposits can be mapped separately upstream of their confluence.
The Lower Pleistocene deposits of Rhine, Meuse and the Belgian rivers show a clear interrelationship. They are bounded by two regional well-mapable unconformities and are preserved in from west to east changing lithostratigraphical sequences. Revision of the lithostratigraphical schemes in Germany and the Netherlands and the better defined lithostratigraphical position of Meuse deposits in Germany now strongly constrain the correlation of the various fluvial deposits. As a result existing reconstructions of the fluvial deposition and tectonic history of the southern Roer Valley Graben can be evaluated and re-adjusted.
It is concluded that the main course of the Meuse was aligned through the so-called East Meuse valley during the larger part of the Early Pleistocene. Available pollen data do not conflict with this conclusion. At the same time the Rhine ceased to enter the southern part of the Roer Valley Graben. Instead, the Meuse accumulated here a series of deposits derived from the East-Meuse valley. Simultaneously, the Belgian rivers filled available accommodation space in the Roer Valley Graben of the southern Netherlands. The conclusions are based primarily on the revised lithostratigraphical framework. In general they simplify the picture of fluvial and tectonic behaviour of the area.