TIMING AND DURATION OF THE PROGRESSIVE DEFORMATION OF THE BRABANT MASSIF, BELGIUM
Structural Geology & Tectonics Group, Katholieke Universiteit Leuven, Redingenstraat 16, B-3000 Leuven.
Geodynamics & Geofluids Research Group, Katholieke Universiteit Leuven, Celestijnenlaan 200C, B-3000 Leuven.
Structural Geology & Tectonics Group, Katholieke Universiteit Leuven, Redingenstraat 16, B-3000 Leuven.
Onderzoekseenheid Paleontologie, Vakgroep Geologie en Bodemkunde, Universiteit Gent, Krijgslaan 281, S8, B-9000
Geodynamics & Geofluids Research Group, Katholieke Universiteit Leuven, Celestijnenlaan 200C, B-3000 Leuven.
Eenheid Geochronologie, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel
Abstract
A comparison of structural, geophysical, metamorphic, stratigraphical and sedimentological data suggests that the progressive deformation of the Brabant Massif, the Brabantian orogeny, is more diachronous than commonly thought. Apparently, the Cambrian core of the massif was already deforming by the late Llandovery, whereas the Ludlow deposits below the angular unconformity probably did not experience deformation prior to the late Pragian. Hence, the Brabant Massif experienced a long-lived deformation history, lasting for at least ~30 Ma.
The slow, progressive deformation model is supported by 40Ar/39Ar dating of syn- to post-cleavage, metamorphic muscovite/sericite grains. The 40Ar/39Ar spectra indicate that episodic metamorphic fluid circulation occurred between ~426 and ~393 Ma. This time interval corresponds to that of the progressive deformation inferred from structural, geophysical, metamorphic, stratigraphical and sedimentological observations.