Brittle-Ductile Deformation
Behaviour in the Middle Crust
as Exemplified by Mullions (Former "Boudins")
in the High-Ardenne Slate Belt, Belgium

By Ilse Kenis
December 2004
Leuven University Press
ISBN: 9058674452
135 pages, Illustrated, 8 ¼" x 11 ¾"
$99.50 Paper Original

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In the High-Ardenne slate belt multilayer sequences occur, consisting of pelite intercalated with psammite layers. The psammite layers are commonly characterized by the particular occurrence of arrays of quartz veins, which are oriented at high angle to the bedding. In between two adjacent veins, the pelite-psammite interface is characterized by a cylindrical cuspate-lobate geometry.

Describing the structures and their geometry introduced the terms "boudin" and "boudinage." In the current literature, boudinage refers to the process of layer-parallel extension of competent layers embedded in a more incompetent matrix. Confronted with this kinematic definition, it remained until recently a matter of controversy whether or not this definition applies to the structures in the High-Ardenne slate belt, i.e. the "boudinage" question.

Contents include: Introduction, "Boudins" in the Ardenne-Eifel area. A historical review, Geodynamic setting, Structural Analysis, Fluid flow and formation of the veins, Kinematic model, Numerical mullion model and parameter sensitivity analysis, Rheology of psammites deforming in the middle crust, Discussion, Conclusions.

Geology
Aardkundige Mededelingen, No. 14

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