Timing of magmatism, foreland basin development, metamorphism and inversion in the Anglo-Brabant fold belt

Abstract

New data implying crustal activation of Eastern Avalonia along the Anglo-Brabant fold belt are presented. Late Ordovician subduction-related magmatism in East Anglia and the Brabant Massif, coupled with accelerated subsidence in the Anglia Basin and in the Brabant Massif during Silurian time, indicate a foreland basin development. Final collision resulted in folding, cleavage development and thrusting during the mid-Lochkovian to mid-Eifelian. In the southeast of the Anglo-Brabant fold belt, Acadian deformation produced basin inversion and the regional antiformal structure of the Brabant Massif. The uplift, inferred from the sedimentology, petrography and reworked palynomorphs in the Lower Devonian of the Dinant Synclinorium is confirmed by illite crystallinity studies. The tectonic model discussed implies the presence of two subduction zones in the eastern part of Eastern Avalonia, one along the Anglo-Brabant fold belt and another under the North Sea in the prolongation of the North German-Polish Caledonides.

Contractional kink bands formed by stress deflection along pre-existing anisotropies? Examples from the Anglo-Brabant Deformation Belt (Belgium) and the North Dobrogea Orogen (Romania)

“…3) is a poorly exposed NW-SE-trending Lower Palaeozoic slate belt, composed of lowgrade lowermost Cambrian to upper Silurian siliciclastic sequences, situated within the subsurface of N-Belgium and SE-England (Van Grootel et al, 1997). Within the Belgian part of this slate belt, called the Brabant Massif, the deformed Lower Palaeozoic sequences are unconformably overlain by subhorizontal to gently dipping, virtually undeformed, diagenetic Middle Devonian and younger sequences (Legrand, 1968;De Vos et al, 1993;Van Grootel et al, 1997;Verniers et al, 2002). Within the Brabant Massif, there is only evidence for one (pre-kink band) single-phase progressive deformation event, called the Brabantian deformation, which took place between the late Llandovery and the Middle Devonian (Debacker, 2001;Verniers et al, 2002;Debacker et al, 2005a and references therein).…”

Transitional geometries between gently plunging and steeply plunging folds: an example from the Lower Palaeozoic Brabant Massif, Anglo-Brabant deformation belt, Belgium

“…1) forms the southeastern part of the Anglo-Brabant deformation belt, one of the fold belts of eastern Avalonia (Van Grootel et al 1997;Verniers et al 2002). The massif comprises low-grade, mainly fine-grained, siliciclastic deposits, ranging from the earliest Cambrian to the late Silurian in age.…”

“…The massif comprises low-grade, mainly fine-grained, siliciclastic deposits, ranging from the earliest Cambrian to the late Silurian in age. An angular unconformity separates these deformed, low-grade Lower Palaeozoic deposits from overlying, diagenetic, undeformed Givetian deposits (Legrand 1967;De Vos et al 1993b;Van Grootel et al 1997;Debacker et al 1999). At present, there is evidence only for a single progressive deformation event, currently considered to have taken place between the Llandovery and the end of the Early Devonian, possibly continuing into the Eifelian (Debacker 2001;Debacker et al 2002;Verniers et al 2002).…”

“…2). The folds plunge steeply to the NW, have straight limbs, a Z-shaped geometry, steeply northdipping, east-west-trending axial surfaces, open interlimb an- et al 1993b;Van Grootel et al 1997) showing the position of the study area (see Fig. 2).…”

Alteration and fluid characteristics of a mineralised shear zone in the Lower Palaeozoic of the Anglo-Brabant belt, Belgium

“…Deformation and metamorphism of the Brabant Massif occurred during the Early to early Middle Devonian (Van Grootel et al, 1997). The study area is located at the southern edge of the Brabant Massif ( Fig.…”