Large-scale relief development related to Quaternary tectonic uplift of a Proterozoic-Paleozoic basement: The Armorican Massif, NW France

The topography of basements located in intraplate domains has often been interpreted in terms of planation theory by examining the remnants of paleosurfaces. In this paper, we address the significance of the present-day drainage networks that erode such topographies by looking at the relief development on the Armorican Massif basement (northwestern France). Using digital elevation model (DEM) analysis, the topography of this massif is characterized by large-scale (similar to 250 km) relief variations that define high elevation domains (HEDs). These domains control the pattern of drainage networks by setting the location of the main drainage divides and the polarity of the regional slopes. Large-scale relief is strongly associated with the existence of scarps along inherited fault zones, suggesting that relief development is mainly controlled by tectonics through fault reactivation, A surface evolution study shows that drainage networks developed during the Quaternary, which corresponds to the timing of the tectonic activity which also led to relief development. The study of Quaternary fluvial erosion through a new method for measuring incision shows that the drainage basins of the HEDs record greater amounts of base level fall during Quaternary times. This implies that differential uplift is responsible for the large-scale relief development of the Armorican Massif during the Quaternary. Our study suggests that as seen in active settings, the topography of basements corresponds to a dynamic signal between tectonics and erosional processes which can be used, for example, in the study of intraplate deformation.