The detailed structural analysis of a large sector of the Eastern Dolomites has been carried out. The field work based on existing unpublished geological maps, has been concentrated on the reconstruction of the major tectonic elements as well as on the unravelling of the complex regmatic system affecting the area. Mesostructural data have been collected throughout the area and analysed using well tested computer aided methodologies. From each station of measurements the three principal stress axes have been obtained. These results permit to reconstruct the tectonic stratigraphy of the area. According to the superposition of striae and similar relationships criteria, four compressional events have been recognised. The average directions of the sigma1 axes are N58°, N26°, N346° and N307°, from older to younger, respectively. Unfortunately, due to the age of the affected rocks (Permian-Triassic), only the relative chronology of the phases has been established. However, by comparison with the results of a similar study carried out in other sectors of the Southern Alps, these phases can be tentatively dated as pre-Oligocene, Chattian-Burdigalian, Serravalian-Tortonian and Late Messinian-Early Pliocene, respectively. The results also allow some conclusions concerning the temporal evolution of the stress ellipsoid whose shape changed from triaxial and purely compressional (subvertical sigma3), to triaxial and transcurrent (subvertical sigma2) via an intermediate stage with uniaxial geometry (sigma2 = sigma3). The possible plate-wide significance of the results is also discussed.
The polyphase tectonics of Eastern Dolomites, Italy
CAPUTO, Riccardo
1996
Abstract
The detailed structural analysis of a large sector of the Eastern Dolomites has been carried out. The field work based on existing unpublished geological maps, has been concentrated on the reconstruction of the major tectonic elements as well as on the unravelling of the complex regmatic system affecting the area. Mesostructural data have been collected throughout the area and analysed using well tested computer aided methodologies. From each station of measurements the three principal stress axes have been obtained. These results permit to reconstruct the tectonic stratigraphy of the area. According to the superposition of striae and similar relationships criteria, four compressional events have been recognised. The average directions of the sigma1 axes are N58°, N26°, N346° and N307°, from older to younger, respectively. Unfortunately, due to the age of the affected rocks (Permian-Triassic), only the relative chronology of the phases has been established. However, by comparison with the results of a similar study carried out in other sectors of the Southern Alps, these phases can be tentatively dated as pre-Oligocene, Chattian-Burdigalian, Serravalian-Tortonian and Late Messinian-Early Pliocene, respectively. The results also allow some conclusions concerning the temporal evolution of the stress ellipsoid whose shape changed from triaxial and purely compressional (subvertical sigma3), to triaxial and transcurrent (subvertical sigma2) via an intermediate stage with uniaxial geometry (sigma2 = sigma3). The possible plate-wide significance of the results is also discussed.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
