Early Palaeozoic orogenic events north of the Rheic suture (Brabant, Ardenne): A review

Abstract

The Lower Palaeozoic rocks exposed in the Brabant-Ardenne region (Belgium, France) recorded the Early Palaeozoic history on the southern margin of the perigondwanan microcontinent of Avalonia, north of the Rheic suture. These rocks crop out in the Brabant basement and in the Ardenne basement inliers within the Variscan Ardenne allochthon. The two main unconformities are classically associated with distinct orogenic episodes, the Late Ordovician ''Ardennian'' event and the Early Devonian ''Brabantian'' event. A review of the current state-of-knowledge with respect to the reconstruction of Early Palaeozoic geodynamics in the Brabant-Ardenne region is presented. It is demonstrated that an unconformity does not necessarily represent an orogenic event, and that the hiatus related to an unconformity does not necessarily coincide with tectonic activity, especially when tectonism is diachronous in nature. The former applies to the Ardennian unconformity, while the latter applies to the Brabantian unconformity. Finally, the well-constrained Brabantian orogeny, as well as the Ardenne-Eifel basin development, is tentatively framed within the Early Palaeozoic geodynamic context of the northern margin of the Rheic realm. By doing so, it is shown that the Brabant-Ardenne region links, both in space and time, the Rheic and Rhenohercynian ocean. To cite this article: M.

A new geological map of the outcrop areas of the Brabant Massif (Belgium)

“…1A). Both areas form part of the "AngloBrabant Deformation Belt" (ABDB; Pharaoh et al, 1993Pharaoh et al, , 1995Van Grootel et al, 1997), a predominantly concealed slate belt along the E-side of the Neoproterozoic Midlands Microcraton (Sintubin et al, 2009). To the S, SW and SE, the Brabant Massif is separated by a Givetian angular unconformity from overlying relatively undeformed Devonian to Carboniferous deposits of the Namur Basin.…”

“…3; cf. Mansy et al, 1999;Sintubin et al, 2009;Belanger et al, 2012). To the south, the Brabant Parautochthon is tectonically overlain by the Ardenne Allochthon via the Midi-Aachen Fault System which marks the Variscan Thrust Front (Figs 1A, 3).…”

“…3) straddles the central part of the Midi-Aachen Fault System. These Lower Palaeozoic rocks also belong to the Anglo-Brabant Deformation Belt but are now incorporated within Variscan thrust sheets along the leading edge of the Ardennes Allochthon (Verniers et al, 2002a;Debacker & Vanmeirhaeghe, 2007;Sintubin et al, 2009;Belanger et al, 2012;Herbosch & Verniers, 2014).…”

“…As part of the "AngloBrabant Deformation Belt", the Brabant Massif is currently considered to be situated above the boundary of two lithospheric blocks, the Midlands Microcraton to the SW and the Southern North Sea -Lüneberg Terrane to the NE ( Fig. 1A; Verniers et al, 2002a;Sintubin & Everaerts, 2002;Sintubin et al, 2009).…”

“…There is evidence only for one single progressive compressional deformation event, now called the Brabantian deformation event (Debacker, 2001;Verniers et al, 2002a;Sintubin et al, 2009;Debacker, 2012). The main features associated with this deformation are folds and a well-developed cogenetic cleavage.…”