Contrasting tectonic records in pre-Alpine metabasites of the Southern Alps (lake Como, Italy)

Paola, Silvia di; Spalla, Maria Iole

doi:10.1016/s0264-3707(99)00032-0

Cited by 21 publications

(10 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Exhumation paths were characterized by cooling or by increasing temperature during decompression (e.g. Brodie, Rex & Rutter, 1989; di Paola & Spalla 2000) and were generally accomplished under a high thermal regime. HT Permian–Triassic mineral associations have never been detected in the pebbles of Permian conglomerates from the Orobic Alps, suggesting that HT rocks were not yet exposed in their Variscan source areas before the late Permian – Triassic period (Spalla et al 2009; Zanoni, Spalla & Gosso, 2010).…”

Section: Natural Datamentioning

confidence: 99%

Thermo-mechanical numerical model of the transition from continental rifting to oceanic spreading: the case study of the Alpine Tethys

et al. 2016

Self Cite

View full text Add to dashboard Cite

We develop a two-dimensional thermo-mechanical numerical model in which the formation of oceanic crust and serpentinite due to the hydration of the uprising mantle peridotite has been implemented, with the aim of discussing the behaviour of the lithosphere of the Alps and Northern Apennines during the transition from continental rifting to ocean spreading of the Alpine Tethys. The predictions of the model are compared with natural data related to the Permian–Triassic high-temperature – low-pressure (HT-LP) metamorphism affecting the continental lithosphere and data from the JurassicP–Tevolution of the oceanic lithosphere from the Alps and the Northern Apennines. Our analysis indicates that a thinned continental crust, an ocean–continent transition zone and an oceanic lithosphere characterize the final structure of the system in a poor magma rift pre-Alpine configuration. We also find that mantle serpentinization starts before crustal break-up and that denudation occurs before ocean spreading. The mantle denudation starts several million years before the gabbros/basalt formation, generating an ocean–continent transition zone from the passive continental margin to the oceanic lithosphere of size 160–280 km. The comparative analysis shows that the extension of a hot and weak lithosphere, which promotes the development of hyperextended Alpine margins, better agrees with the natural data. Finally, our comparative analysis supports the hypothesis that the lithospheric extension preceding the opening of the Alpine Tethys did not start in a stable continental lithosphere, but developed by recycling part of the old Variscan collisional suture.

show abstract

Section: Natural Datamentioning

confidence: 99%

Thermo-mechanical numerical model of the transition from continental rifting to oceanic spreading: the case study of the Alpine Tethys

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…In places, contact aureole developed in country rocks of shallow intrusions (34). Exhumation was characterized by decompressional cooling [e.g., Brodie et al , 1989] or by increasing temperature during decompression [e.g., di Paola and Spalla , 2000]. Generally, the exhumation paths are characterized by high T/P.…”

Section: Geological Outlinementioning

confidence: 99%

Permian‐Triassic high thermal regime in the Alps: Result of late Variscan collapse or continental rifting? Validation by numerical modeling

Marotta

Spalla

2007

Tectonics

Self Cite

View full text Add to dashboard Cite

[1] The Permian-Triassic igneous activity, associated with regional scale deformation developed under high-temperature/low-pressure (HT-LP) metamorphic conditions and widely recorded in the pre-Alpine crust of the European Alps, can result from late orogenic collapse of a collisional belt or from lithospheric thinning leading to a continental rifting process. In order to reduce this ambiguity, we use a two-dimensional finite element model to give new insights on the sequence of mechanisms operating during active ocean-continent convergence, followed by continental collision and pure gravitational evolution and on the regional geodynamic interpretation of the Paleozoic-Mesozoic evolution of the Alpine area. The modeling predictions are compared with the PT climax conditions of Variscan and Permian-Triassic metamorphism affecting the continental crust of the Helvetic to Southalpine domains. The good agreement between model predictions and natural data realized for the early to Neovariscan evolution indicates that during Paleozoic, the pre-Alpine crust of the Alps was part of an active ocean-continent convergence margin and an intracontinental suture zone. Furthermore, modeling results support the interpretation envisaging a Permian-Triassic lithospheric extension as responsible for the HT metamorphism and related intense igneous activity. This evolution was precursor of the Mesozoic oceanization, during which the tectonic units, coupled and accreted during the Variscan subduction and collision, were separated to form the two passive European and Adriatic continental margins.

show abstract

“…therein). Any relationship with the Permian-Triassic high thermal state that characterized the DOZ [25,52,73,74] is precluded since the SCB was already exhumed at that time. The identified high thermal state is thus interpreted as related to a Variscan late-orogenic thinning, associated with lithospheric delamination.…”

Section: Discussionmentioning

confidence: 99%

“…the Dervio-Olgiasca Zone (DOZ), which is the only TMU that records the high thermal state relatable to the "Tethyan rifting" at intermediate crustal depth [25,27]. Andalusite replacing sillimanite testifies to exhumation under high T/P ratio [25,52,73,74]. The Triassic age of this event is constrained by syn-D2 pegmatite ages [25,34,70,75]; 5.…”

Section: Geological Settingmentioning

confidence: 99%

Cld-St-And-Bearing Assemblages in the Central Southalpine Basement: Markers of an Evolving Thermal Regime during Variscan Convergence

et al. 2021

Self Cite

View full text Add to dashboard Cite

Multiscale structural analysis was carried out to explore the sequence of superposed pre-Alpine chloritoid–staurolite–andalusite metamorphic assemblages in the polydeformed Variscan basement of the upper Val Camonica, in the central Southalpine domain. The dominant fabric in the upper Val Camonica basement is the late-Variscan S2 foliation, marked by greenschist facies minerals and truncated by the base of Permian siliciclastic sequences. The intersection with the sedimentary strata defines a Permianage limit on the pre-Alpine tectonometamorphic evolution and exhumation of the Variscan basement. The detailed structural survey revealed that the older S1 foliation was locally preserved in low-strained domains. S1 is a composite fabric resulting from combining S1a and S1b: in the metapelites, S1a was supported by chloritoid, garnet, and biotite and developed before S1b, which was marked by staurolite, garnet, and biotite. S1a and S1b developed at intermediate pressure amphibolite facies conditions during the Variscan convergence, S1a at T = 520–550 °C and P ≃ 0.8 GPa, S1b at T = 550–650 °C and P = 0.4–0.7 GPa. The special feature of the upper Val Camonica metapelites is andalusite, which formed between the late D1b and early D2 tectonic events. Andalusite developed at T = 520–580 °C and P = 0.2–0.4 GPa in pre-Permian times, after the peak of the Variscan collision and before the exhumation of the Variscan basement and the subsequent deposition of the Permian covers. It follows that the upper Val Camonica andalusite has a different age and tectonic significance as compared to that of other pre-Alpine andalusite occurrences in the Alps, where andalusite mostly developed during exhumation of high-temperature basement rocks in Permian–Triassic times.

show abstract

Contrasting tectonic records in pre-Alpine metabasites of the Southern Alps (lake Como, Italy)

Cited by 21 publications

References 21 publications

Thermo-mechanical numerical model of the transition from continental rifting to oceanic spreading: the case study of the Alpine Tethys

Thermo-mechanical numerical model of the transition from continental rifting to oceanic spreading: the case study of the Alpine Tethys

Permian‐Triassic high thermal regime in the Alps: Result of late Variscan collapse or continental rifting? Validation by numerical modeling

Cld-St-And-Bearing Assemblages in the Central Southalpine Basement: Markers of an Evolving Thermal Regime during Variscan Convergence

Contact Info

Product

Resources

About