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Etude et caractérisation des structures hercyniennes à partir de données sismologiques : le cas du Massif Armoricain

Abstract : The Hercynian Range is a major object of the european tectonics, however its deep structure remains poorly known. The Armorican Massif is a preserved segment of this mountain range, the general trend is oriented NW-SE, parallel to the trend of the range in this region. Three domains are usually distinguished (North-, Central-, and South-Armorican Domains), separated by two main fault zones (North- and South-Armorican Shear Zones). The Armorican Massif presents the advantage of beeing preserved from important tectono-thermal event since the end of the collision, thus, it stands for a particularly intersting place for the study of an old collision range. In the framework of the GeoFrance3D-ARMOR2 project, two seismological field experiments has been run in 1997 and 1999 in the Armorican Massif. The aims were : (1) the determination of the depth extension of the shear zones ; (2) the determination of their deep geometry ; (3) the detailed mapping of the Champtoceaux Nappes (high pressure rocks exhumated at the early stage of the hercynian collision). The data collected during the field experiments were used to map seismic anisotropy at depth and to build a three-dimensional model of the P -wave velocity variations beneath the Armorican Massif. According to the crustal images, there is no evidence of the supposed rooting of the Champtoceaux Nappes in the lower crust. Nevertheless, the upper mantle images show a clear signal which is interpreted as the signature of a north-dipping subduction process ending during Devonian (~350 Ma) followed by a transpressif regime during Carboniferous. The results also show that the depth extension of the North-Armorican Shear Zone is limited to the crust while the South-Armorican Shear Zone can be observed down to more than 150 km.
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https://tel.archives-ouvertes.fr/tel-00001738
Contributor : Sébastien Judenherc <>
Submitted on : Wednesday, April 16, 2003 - 12:07:38 AM
Last modification on : Friday, April 5, 2019 - 8:16:14 PM
Long-term archiving on: : Monday, September 20, 2010 - 12:09:35 PM

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  • HAL Id : tel-00001738, version 2

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Sébastien Judenherc. Etude et caractérisation des structures hercyniennes à partir de données sismologiques : le cas du Massif Armoricain. Géologie appliquée. Université Louis Pasteur - Strasbourg I, 2000. Français. ⟨tel-00001738v2⟩

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