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Fernand Geukens

"Strike slip deformation" des deux côtés du Graben de Malmedy

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Annexes

Résumé

Les bassins permiens de Basse-Bodeux et Malmedy ont une direction varisque SW-NE et sont remplis de formations rougeâtres conglomératiques. Ils appartiennent à un graben qui divise le Massif de Stavelot en deux: au Nord domine une direction hercynienne SW-NE aussi bien dans les plis que dans les failles, au Sud on observe surtout une direction calédonienne WE. Des deux côtés du graben on constate de nombreux charriages provoqués par des décrochements horizontaux (left hand strike slip). L'origine et la sédimentation des bassins permiens semblent être en rapport avec ces mouvements de type strike slip. L'emplacement du graben a été influencé par des structures tectoniques anciennes.

Abstract

The Stavelot Massif can be divided in two different parts. The northern part is characterised by a general NE-SW strike, parallel to the Hercynian direction. Both the faults and the fold axes have this strike direction. The southern part is characterised by an W-E strike parallel to the Caledonian direction. Between these two parts exists a graben (Malmedy) filled with conglomeratic beds of Permian age. North as well as south of the Malmedy graben exists a strike slip fault system (dir. N50-60°E). The strike slip movements along this fault system are indicated north of the graben by the overthrust near Bra (the Ordovician thrusted over the Gedinnian), near Les Vilettes (Rv4 (Cambrian) thrusted over the Ordovician)) near Haute-Bodeux (Rv4-Rv3 thrusted over the Ordovician) and in the forest Derrière le Tige (Rv2 thrusted over the Rv3-Rv4). The tectonic structure south of the graben is also dominated by strike slip movements. Strike-slip faults are often associated with stepovers. In this model the two Permian basins (Stavelot-Malmedy and Basse-Bodeux) can be explained as pull-apart basins formed in connection with overstep structures. Stepovers as well as pull-apart basins are ascertained in many places along strike-slip deformations. Old Caledonian as well as Hercynian structures may have had an influence on the location of the Permian basins.

To cite this article

Fernand Geukens, «"Strike slip deformation" des deux côtés du Graben de Malmedy», Annales de la Société géologique de Belgique [En ligne], Fascicule 2, Volume 118 (1995), 139-146 URL : https://popups.ulg.ac.be/0037-9395/index.php?id=2102.

About: Fernand Geukens

Laboratorium Algemene Geologie Redingenstraat 16, 3000 Leuven, Belgie.