The "Bois du Peu" thrust sheets (external French Jura mountains):re-examining the concept of "Fault-Fold"

Grégory Bièvre (1, 2) , Eric Mercier (3)

1 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
2 CETE de Lyon - Centre d'études techniques de l'équipement de Lyon
3 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]

Significant reconnaissance field work along a road project which crosses the site of the “Bois du Peu" thrust sheets (near Besançon, Eastern France), provides us the opportunity to re-examine the concept of “fault-folding" (in french, “faille-pli”) which was introduced by Glangeaud (1944) to account for the observed tectonics of the Jura mountains and, more specifically, external Jura. From a theoretical point of view, we contend that this concept is incompatible with general principles of balanced cross-sections and has to be rejected. We show that in the “Bois de Peu" area, data fit with a deformation model which associates several modes of folding (fault-propagation fold and fault-bend fold). The decollement level related to these folds is located into Keuper strata, Oxfordian-Argovian levels being used locally as a secondary decollement level.

Keywords: Fault-fold; Jura mountains; "Fault-fold"; Décollement tectonics; Balanced cross-sections; Forward modelling

Domains: Tectonics; Global Changes

Grégory Bièvre, Eric Mercier. The "Bois du Peu" thrust sheets (external French Jura mountains):re-examining the concept of "Fault-Fold". 2010. ⟨insu-00442191v2⟩