The Triassic succession of the central Southern Alps (Italy) is stacked into several units bounded by south-verging low-angle thrust faults, which are related to two successive steps of crustal shortening. The thrust surfaces are cut by high-angle extensional and strike-slip faults, which controlled the emplacement of hypabissal magmatic intrusions that post-date thrusts motions. Intrusion ages based on SHRIMP U-Pb zircon dating span between 42 ± 1 and 39 ± 1 Ma, suggesting close time relationships with the earliest Adamello intrusion stages and, more in general, with the widespread calc-alkaline magmatism described in the Southern Alps. Fission-track ages of magmatic apatites are indistinguishable from U-Pb crystallization ages of zircons, suggesting that the intrusion occurred in country rocks already exhumed above the partial annealing zone of apatite (depth < 2-4 km). These data indicate that the central Southern Alps were already structured and largely exhumed in the Middle Eocene. Although we describe minor faults affecting magmatic bodies and local reactivations of older structures, no major internal deformations have occurred in the area after the Bartonian. Neogene deformations were instead concentrated farther south, along the frontal part of the belt. © 2010 Springer-Verlag

D'Adda, P., Zanchi, A., Bergomi, M., Berra, F., Malusa', M., Tunesi, A., et al. (2011). Polyphase thrusting and dyke emplacement in the central Southern Alps (Northern Italy). INTERNATIONAL JOURNAL OF EARTH SCIENCES, 100(5), 1095-1113 [10.1007/s00531-010-0586-2].

Polyphase thrusting and dyke emplacement in the central Southern Alps (Northern Italy)

D'ADDA, PAOLO;ZANCHI, ANDREA MARCO;BERGOMI, MARIA ALDINA;MALUSA', MARCO GIOVANNI;TUNESI, ANNALISA MARIA;ZANCHETTA, STEFANO
2011

Abstract

The Triassic succession of the central Southern Alps (Italy) is stacked into several units bounded by south-verging low-angle thrust faults, which are related to two successive steps of crustal shortening. The thrust surfaces are cut by high-angle extensional and strike-slip faults, which controlled the emplacement of hypabissal magmatic intrusions that post-date thrusts motions. Intrusion ages based on SHRIMP U-Pb zircon dating span between 42 ± 1 and 39 ± 1 Ma, suggesting close time relationships with the earliest Adamello intrusion stages and, more in general, with the widespread calc-alkaline magmatism described in the Southern Alps. Fission-track ages of magmatic apatites are indistinguishable from U-Pb crystallization ages of zircons, suggesting that the intrusion occurred in country rocks already exhumed above the partial annealing zone of apatite (depth < 2-4 km). These data indicate that the central Southern Alps were already structured and largely exhumed in the Middle Eocene. Although we describe minor faults affecting magmatic bodies and local reactivations of older structures, no major internal deformations have occurred in the area after the Bartonian. Neogene deformations were instead concentrated farther south, along the frontal part of the belt. © 2010 Springer-Verlag
Articolo in rivista - Articolo scientifico
Southern Alps, fold and thrust belt, structural analysis, calc-alkaline magmatism, U/Pb zircon age, apatite fission tracks
English
2011
100
5
1095
1113
none
D'Adda, P., Zanchi, A., Bergomi, M., Berra, F., Malusa', M., Tunesi, A., et al. (2011). Polyphase thrusting and dyke emplacement in the central Southern Alps (Northern Italy). INTERNATIONAL JOURNAL OF EARTH SCIENCES, 100(5), 1095-1113 [10.1007/s00531-010-0586-2].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/22619
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