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| Titel |
Magnetic fabrics in overthrusted terrains: example from the Buntsandstein Facies in the southern edge of the Axial Zone (Nogueres unit, Central Pyrenees) |
| VerfasserIn |
E. Izquierdo Llavall, A. Casas Sainz, B. Oliva Urcia |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058987
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| Zusammenfassung |
| Magnetic fabrics in deformed domains are a source of information of the strain rate and the
tectonic evolution of the rocks. The present study shows the results derived from the
application of this methodological approach to the Permian-Triassic red beds in the western
sector of the Nogueres unit and eastern sector of the Gavarnie thrust sheet (Central Pyrenees).
From the structural point of view, the sampled domain constitutes a key area since it is
located in the transition between the antiformal stack of the Axial Zone to the West, including
non-overturned basement thrust sheets, and the têtes plongeantes domain of the Nogueres
unit to the East. The latter comprises three folded thrust sheets, involving Stephanian,
Permian and Triassic rocks, whose fronts define several synformal anticlines. Alpine
cleavage is generally absent within the têtes plongantes domain but Triassic outcrops
located North and West are affected by WNW-ESE-striking, North-dipping cleavage
planes.
Samples for the study of the anisotropy of magnetic susceptibility were collected
from 31 sites, distributed throughout the different structural domains (in the têtes
plongeantes domain and in the red beds unconformably overlying the Paleozoic,
North and West of the Nogueres unit). Measurements of the magnetic fabric were
made at room and low temperature (~77ºK) with a KLY-3S susceptibility meter
(AGICO, Czech Republic) that combined with a CS-3 apparatus was also used to
perform thermomagnetic runs. Mean magnetic susceptibility (Km) in the sampled sites
ranges between 35 and 221-
10-6 S.I. It is lower in the sandstones ( |
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