Folds and cleavage/fold relationships in the Brabant Massif, southeastern Anglo-Brabant Deformation Belt
Abstract
Detailed analyses of folds and cleavage/fold relationships within the Lower Palaeozoic Brabant massif have resulted in the recognition of pre-cleavage folds, three types of syn-cleavage folds, and two broad types of post-cleavage folds. These detailed analyses, and their integration with data from other sources, have led to major advances in our understanding of the Brabant Massif. The distribution of the different fold types yields significant insight into the small- and large-scale influence of pre-existing sedimentological, lithological and deformation features on the final deformation geometry. Changes in lithology and sedimentology result in different types of syn-cleavage folds, slump folds and local competent magmatic bodies control the position and to some extent also the orientation of syn-cleavage folds and on a larger scale also early basin-bounding features exert a major control on later deformation geometries. Moreover, combined with other data, the analysis of folds and cleavage/fold relationships provides valuable information on the large-scale architecture of the Brabant Massif, and on the evolutionary history of the Brabant Basin, from initial basin development to the final stages of basin inversion and gravitational collapse, and this both in time and in space. As illustrated herein, a thorough inventory of numerous detailed analyses of folds and cleavage/fold relationships is an absolute necessity for an understanding of the structural architecture, evolutionary history and tectonic significance of fold belts and slate belts.