Late Quaternary activity of the Feldbiss Fault Zone, Roer Valley Rift System, the Netherlands, based on displaced fluvial terrace fragments

Abstract

The Meuse River crosses the Feldbiss Fault Zone, one of the main border fault zones of the Roer Valley Graben in the southern part of the Netherlands. Uplift of the area south of the Feldbiss Fault Zone forced the Meuse River to incise and, as a result, a flight of terraces was formed. Faults of the Feldbiss Fault Zone have displaced the Middle and Late Pleistocene terrace deposits. In this study, an extensive geomorphological survey was carried out to locate the faults of the Feldbiss Fault Zone and to determine the displacement history of terrace deposits. The Feldbiss Fault Zone is characterized by an average displacement rate of 0.041–0.047 mm a −1 during the Late Pleistocene. Individual faults show an average displacement rate ranging between 0.010 and 0.034 mm a −1. The spatial variation in displacement rates along the individual faults reveals a system of overstepping faults. These normal faults developed by reactivation of Paleozoic strike-slip faults. As fault displacements at the bases of the younger terrace deposits are apparently similar to the tops of the adjacent older terrace, the age of these horizons is the same within thousands of years. This implies that the model of terrace development by rapid fluvial incision followed by slow aggradation does apply for this area.