Erosion Surfaces in the Ardenne–Oesling and Their Associated Kaolinic Weathering Mantle

Abstract

International audienceThis chapter deals with the long-term geomorphology of the Paleozoic Ardenne–Oesling massif of S Belgium and the landforms that currently attest the very long persistence and high resistance to erosion of landscape elements created as far back in time as the Lower Cretaceous in a region of predominantly continental regime and constant low to moderate elevation since the Permian. We first present recent results regarding the antiquity of kaolinic weathering mantles preserved in four sites on or close to the plateau surfaces characteristic of the Ardennian landscape, showing that they record at least three main weathering phases, namely in the Early Cretaceous (extending in the early Late Cretaceous), the Late Paleocene, and the Early Miocene. Then, having provided a working definition of the erosion surface and listed criteria helping recognize them in the landscape, we focus on the Hautes Fagnes massif, the highest NE part of the Ardenne–Oesling. We describe the geometric and sedimentary evidence that allow one to recognize a succession of four erosion surfaces formed during the Cretaceous and the Cenozoic and reconstruct the morphogenetic evolution of the area that responded to the variable interplay of the marine transgression-regression, climatic, and tectonic controls. Finally, we present the few estimates of long-term denudation rates available for the Ardenne massif, fission track and cosmogenic nuclide studies both suggesting Cenozoic denudation rates in the order of a few 10 m/Myr, and comment on their compatibility with field observations

Exploring the regolith with electrical resistivity tomography in large-scale surveys: electrode spacing-related issues and possibility

“…In addition, pointscale observations suggest a probable spatial variability of the subsurface electrical resistivity. Indeed, mirroring mul-tiple weathering phases in the Luxembourgish Ardennes Massif over geological timescales (Moragues-Quiroga et al, 2017;Demoulin et al, 2018), cores obtained from deep drilling campaigns (Fig. 2d) reveal different weathering degrees in the Weierbach catchment (Fig.…”

Genesis and 40Ar/39Ar dating of K-Mn oxides from the Stavelot Massif (Ardenne, Belgium): Insights into Oligocene to Pliocene weathering periods in Western Europe

“…These secondary Fe-Mn enrichments were controlled by the host-rock lithology, the local and regional geomorphology and the Cenozoic climatic conditions (Dill, 1985a). The ages recovered from K-Mn oxides in several of these massifs mostly delimit a Neogene period for weathering (see Table 1 for 40 Ar/ 39 Ar ages; Barbier et al, 2010;Brannath and Smykatz-Kloss, 1992;Bruyère et al, 2003;Demoulin et al, 2018Demoulin et al, , 2010Dill, 1985b;Dill et al, 2010;Dill and Wemmer, 2012;Hautmann and Lippolt, 2000;Segev et al, 1992Segev et al, , 1991Thiry et al, 2006;Yans, 2003).…”

“…1) and documents widely preserved weathering profiles, up to 80 m thick, on Paleozoic sediments (Thiry et al, 2006;Yans et al, 2003). The bedrock underwent a long evolution under tropical conditions (Demoulin et al, 2018). Stratigraphic arguments (age of the cover, tectonics) defined these periods in and around the Ardenne (Dejonghe and Boni, 2005;Dusar and Lagrou, 2007;Quesnel, 2003;Yans, 2003;Yans et al, 2003), but the timing and the duration require careful attention as datable material is often missing between the host rock formation and the cover of the saprolite.…”

“…(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) (2003), Demoulin et al (2018) worldwide for their coticule layers, a metasedimentary yellowish rock composed of fine-grained Mn-garnet (spessartine), quartz and white micas (Baijot et al, 2011;Herbosch et al, 2016;Lamens and Geukens, 1984). These strata have undergone strong weathering leading to the formation of supergene manganese oxides (Blondieau, 2019(Blondieau, , 2006(Blondieau, , 2005Fransolet, 1979;Gustine, 2002;Schreyer et al, 2001).…”

Evaluation of Belgian clays for manufacturing compressed earth blocks

“…Kaolins correspond to a primary type deposit or residual kaolin from the weathering of shales and arkoses. They are present on the Rocroi Massif across the border in France (Voisin, 1995) and on the peneplanated ridges of the High Ardenne (Dupuis et al, 1996, Demoulin et al, 2018.…”