| Titre : |
Early Mesozoic extension and alpine tectonics in the western southern Alps : The geology of the area between Lugano and Menaggio (Lombardy, northern Italy) |
| Type de document : |
texte imprimé |
| Auteurs : |
Giovanni Bertotti, Auteur |
| Editeur : |
Padova : Societa cooperativa tipografica |
| Année de publication : |
1991 |
| Collection : |
Memorie di scienze geologiche, ISSN 0391-8602 num. 43 |
| Importance : |
1 vol. (17-103 p.) |
| Présentation : |
ill.,50 figures, 4 tables, 10 plates |
| Format : |
32 cm |
| Accompagnement : |
1 geological map |
| ISBN/ISSN/EAN : |
PPN 234336749 |
| Note générale : |
Texte remanié de : Doctoral Thesis : ETH Zurich : 1990. - Résumé en anglais, italien et allemand. - La légende de chaque planche est sur une feuille à part |
| Langues : |
Anglais (eng) |
| Tags : |
Tectonique -- Alpes (Italie) Tectonique -- Lombardie (Italie) Failles (géologie) Mésozoïque Geology, Structural -- Alps, Italian (Italy) Geology, Structural -- Lombardy (Italy) Faults (Geology) Geology, Stratigraphic -- Mesozoic |
| Index. décimale : |
551.809 4947 Tectonique - Région alpine |
| Résumé : |
The Southern Alps represent a segment of the Mesozoic South-Alpine passive continental margin which was involved in Alpine shortening in Tertiary times. In this work the large-scale tectonic and sedimentation pattern of two of the most important extensional structures, the Lugano swell and the M. Generoso basin are studied. The regional results are then integrated with data obtained from the literature in order to discuss the extension of the South-Alpine margin at a lithospheric scale. The crystalline basement of the studied area consists of paragneisses and subordinate orthogneisses and amphibolites of Variscan age. The Upper Permian to Carnian sediments were deposited in continental to shallow marine environments and show no abrupt thickness or facies variations. Beginning with the Norian, normal faulting caused dramatic differences in sediment thickness and, sometimes, facies. It is in Norian time that the Lugano swell and the M. Generoso sedimentary basin were individuated. The two domains were separated by the E-dipping Lugano normal fault. Tertiary Alpine tectonics caused the imbrication and the steepening of the northern part of the basin. Also pre-Alpine structures like the northern segment of the Lugano normal fault were steepened. The Lugano normal fault, after erosion, is now exposed at the surface and coincides with the E-W striking M. Grona line of previous authors. The central and western segments of the M. Grona line represent the contact between basement in the north and sediments in the south. The geometry of the Lugano normal fault before Alpine steepening can be reconstructed. The fault was steep (50 °-70 °) from the surface to a depth of ca. 5-7 km. It attained then gentler dips of 10 °-20 ° till a paleo-depth of ca. 15 km. Deformation is always limited to a well definable zone. A similar geometry is shown by the Lago Maggiore fault which controlled the evolution of the M. Nudo basin, west of Lugano. A stretching factor of 1.5 can be reconstructed along a W-E striking profile from the Canavese to the Albenza Plateau. The tectonically-derived crustal stretching factor applies also to the underlying lithospheric mantle. (Abstract shortened by UMI.)
|
| Note de contenu : |
Bibliogr. p.96-103 |
Early Mesozoic extension and alpine tectonics in the western southern Alps : The geology of the area between Lugano and Menaggio (Lombardy, northern Italy) [texte imprimé] / Giovanni Bertotti, Auteur . - Padova : Societa cooperativa tipografica, 1991 . - 1 vol. (17-103 p.) : ill.,50 figures, 4 tables, 10 plates ; 32 cm + 1 geological map. - ( Memorie di scienze geologiche, ISSN 0391-8602; 43) . ISSN : PPN 234336749 Texte remanié de : Doctoral Thesis : ETH Zurich : 1990. - Résumé en anglais, italien et allemand. - La légende de chaque planche est sur une feuille à part Langues : Anglais ( eng)
| Tags : |
Tectonique -- Alpes (Italie) Tectonique -- Lombardie (Italie) Failles (géologie) Mésozoïque Geology, Structural -- Alps, Italian (Italy) Geology, Structural -- Lombardy (Italy) Faults (Geology) Geology, Stratigraphic -- Mesozoic |
| Index. décimale : |
551.809 4947 Tectonique - Région alpine |
| Résumé : |
The Southern Alps represent a segment of the Mesozoic South-Alpine passive continental margin which was involved in Alpine shortening in Tertiary times. In this work the large-scale tectonic and sedimentation pattern of two of the most important extensional structures, the Lugano swell and the M. Generoso basin are studied. The regional results are then integrated with data obtained from the literature in order to discuss the extension of the South-Alpine margin at a lithospheric scale. The crystalline basement of the studied area consists of paragneisses and subordinate orthogneisses and amphibolites of Variscan age. The Upper Permian to Carnian sediments were deposited in continental to shallow marine environments and show no abrupt thickness or facies variations. Beginning with the Norian, normal faulting caused dramatic differences in sediment thickness and, sometimes, facies. It is in Norian time that the Lugano swell and the M. Generoso sedimentary basin were individuated. The two domains were separated by the E-dipping Lugano normal fault. Tertiary Alpine tectonics caused the imbrication and the steepening of the northern part of the basin. Also pre-Alpine structures like the northern segment of the Lugano normal fault were steepened. The Lugano normal fault, after erosion, is now exposed at the surface and coincides with the E-W striking M. Grona line of previous authors. The central and western segments of the M. Grona line represent the contact between basement in the north and sediments in the south. The geometry of the Lugano normal fault before Alpine steepening can be reconstructed. The fault was steep (50 °-70 °) from the surface to a depth of ca. 5-7 km. It attained then gentler dips of 10 °-20 ° till a paleo-depth of ca. 15 km. Deformation is always limited to a well definable zone. A similar geometry is shown by the Lago Maggiore fault which controlled the evolution of the M. Nudo basin, west of Lugano. A stretching factor of 1.5 can be reconstructed along a W-E striking profile from the Canavese to the Albenza Plateau. The tectonically-derived crustal stretching factor applies also to the underlying lithospheric mantle. (Abstract shortened by UMI.)
|
| Note de contenu : |
Bibliogr. p.96-103 |
|
551 Géologie, hydrologie, météorologie
trié(s) par (Pertinence décroissant(e), Titre croissant(e)) Affiner la rechercheEarly Mesozoic extension and alpine tectonics in the western southern Alps (1991)
