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TECTONICS, VOL. 27, TC5005, doi:10.1029/2008TC002282, 2008

Interactions between thin- and thick-skinned tectonics at the northwestern front of the Jura fold-and-thrust belt (eastern France)

Herfried Madritsch

Geologisch-Paläontologisches Institut, University of Basel, Basel, Switzerland


Stefan M. Schmid

Geologisch-Paläontologisches Institut, University of Basel, Basel, Switzerland


Olivier Fabbri

UMR Chrono-Envrionnement, Université de Franche-Comté, Besançon, France


Abstract

This study investigates spatial and temporal interactions of thin- and thick-skinned tectonics in a classical foreland setting located at the front of the Jura fold-and-thrust belt in eastern France. The working area coincides with the intracontinental Rhine-Bresse Transfer Zone and represents the most external front of the deformed Alpine foreland. The investigation combines analyses of largely unpublished and newly available subsurface information with our own structural data, including an exhaustive paleostress analysis and geomorphologic observations. Results are provided in the form of a new tectonic map and a series of regional cross sections through the study area. The Besançon Zone, forming the most external part of the thin-skinned fold-and-thrust belt, encroached onto the Eo-Oligocene Rhine-Bresse Transfer Fault System until early Pliocene times. Thrust propagation was largely controlled by the Late Paleozoic to Paleogene preexisting fault pattern that characterizes the Rhine-Bresse Transfer Zone. Thick-skinned deformation, dominant throughout the Avant-Monts Zone located farther to the west, was associated with compressional to transpressional reactivation of such faults. Overprinting and crosscutting criteria of fault slip data allow distinguishing between systematically fanning maximum horizontal stress axes that define the front of the thin-skinned Jura fold-and-thrust belt and consistently NW–SE directed maximum horizontal stress axes that characterize deformation of the autochthonous cover of the foreland, which is affected by thick-skinned tectonics. Tectonic and geomorphic analyses indicate that thick-skinned tectonics started at a very late stage of foreland deformation (post-early Pliocene). Geomorphic observations imply that deformation between Mesozoic cover and basement is locally still decoupled. However, overprinting relationships and recent seismicity suggest that present-day tectonic activity is thick skinned, which probably reflects ongoing tectonic underplating in the Alpine foreland.

Received 26 February 2008; accepted 18 June 2008; published 4 October 2008.

Keywords: Jura fold-and-thrust belt; thin- and thick-skinned tectonics; paleostress; neotectonics; France.

Index Terms: 8110 Tectonophysics: Continental tectonics: general (0905); 8107 Tectonophysics: Continental neotectonics (8002); 8168 Tectonophysics: Stresses: general; 8005 Structural Geology: Folds and folding; 8010 Structural Geology: Fractures and faults.

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Citation: Madritsch, H., S. M. Schmid, and O. Fabbri (2008), Interactions between thin- and thick-skinned tectonics at the northwestern front of the Jura fold-and-thrust belt (eastern France), Tectonics, 27, TC5005, doi:10.1029/2008TC002282.