The sondalo gabbroic complex (central alps, Northern Italy): evidence for emplacement of mantle-derived melts into amphibolite-facies metapelites

Braga, Roberto; Giacomini, Folco; Messiga, Bruno; Tribuzio, R.

doi:10.1016/s1464-1895(01)00063-1

Cited by 21 publications

(34 citation statements)

References 14 publications

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“…The Campo nappe contains Permian gabbros that were emplaced at a mid-crustal level (Tribuzio et al 1999;Braga et al 2001Braga et al , 2003. 40 Ar/ 39 Ar data on biotite (Meier 2003) as well as K/Ar ages on biotite and muscovite (Meier 2003;Thöni 1981) on the country rocks of this mid-crustal intrusion record cooling ages around 180-200 Ma.…”

Section: Methodology and Problems Of The Paleogeographic Restorationmentioning

confidence: 99%

“…These rocks were intruded by a 300-to 270-Ma old mafic intrusion referred to as the Sondalo gabbro (Koeing 1964;Tribuzio et al 1999). Based on the relations with the surrounding basement rocks as well as P-T estimates of the country rocks of the Sondalo gabbro, Tribuzio et al (1999) and Braga et al (2001Braga et al ( , 2003 concluded that these rocks were intrusive and residing at mid-crustal levels (0.6 ± 0.2 GPa, 900°C) during the Permian. Thermochronological data from Thöni (1981) and Meier (2003) show cooling ages on white micas and biotite by 40 Ar/ 39 Ar and K/Ar ranging between 180 and 200 Ma.…”

Section: Variscan To Permian Basementmentioning

confidence: 99%

“…The section to the right shows a simplified cross-section through the crust in later Permian time, indicating the original position of the rocks found today in the different tectonic units. The P-T-t paths are shown for a pre-rift middle crustal gabbros (Sondalo gabbro Tribuzio et al 1999;Braga et al 2001Braga et al , 2003Meier 2003); b pre-rift upper crustal granitoid (Bernina and Err intrusives (Peters 2005(Peters , 2007); c pre-rift lower crustal rocks (Malenco crust-mantle boundary Villa et al 2000)). The data highlight the exhumation during Jurassic rifting of middle and lower crustal rocks.…”

Section: Variscan To Permian Basementmentioning

confidence: 99%

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Rift-related inheritance in orogens: a case study from the Austroalpine nappes in Central Alps (SE-Switzerland and N-Italy)

Mohn

Manatschal

Masini

et al. 2011

Int J Earth Sci (Geol Rundsch)

100

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The Austroalpine nappe systems in SE-Switzerland and N-Italy preserve remnants of the Adriatic rifted margin. Based on new maps and cross-sections, we suggest that the complex structure of the Campo, Grosina/Languard, and Bernina nappes is inherited largely from Jurassic rifting. We propose a classification of the Austroalpine domain into Upper, Middle and Lower Austroalpine nappes that is new because it is based primarily on the rift-related Jurassic structure and paleogeography of these nappes. Based on the Alpine structures and pre-Alpine, riftrelated geometry of the Lower (Bernina) and Middle (Campo, Grosina/Languard) Austroalpine nappes, we restore these nappes to their original positions along the former margin, as a means of understanding the formation and emplacement of the nappes during initial reactivation of the Alpine Tethyan margin. The Campo and Grosina/ Languard nappes can be interpreted as remnants of a former necking zone that comprised pre-rift upper and middle crust. These nappes were juxtaposed with the Mesozoic cover of the Bernina nappe during Jurassic rifting. We find evidence for low-angle detachment faults and extensional allochthons in the Bernina nappe similar to those previously described in the Err nappe and explain their role during subsequent reactivation. Our observations reveal a strong control of rift-related structures during the subsequent Alpine reactivation on all scales of the former distal margin. Two zones of intense deformation, referred to as the Albula-Zebru and Lunghin-Mortirolo movement zones, have been reactivated during Alpine deformation and cannot be described as simple monophase faults or shear zones. We propose a tectonic model for the Austroalpine nappe systems that link inherited, rift-related structures with present-day Alpine structures. In conclusion, we believe that apart from the direct regional implications, the results of this paper are of general interest in understanding the control of rift structures during reactivation of distal-rifted margins.

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Section: Methodology and Problems Of The Paleogeographic Restorationmentioning

confidence: 99%

Section: Variscan To Permian Basementmentioning

confidence: 99%

Section: Variscan To Permian Basementmentioning

confidence: 99%

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Rift-related inheritance in orogens: a case study from the Austroalpine nappes in Central Alps (SE-Switzerland and N-Italy)

Mohn

Manatschal

Masini

et al. 2011

Int J Earth Sci (Geol Rundsch)

100

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“…Tribuzio et al 1999). The metamorphism in the country rocks is characterized by upper greenschist to amphibolite facies mineral assemblages, while narrow granulite facies metamorphism is locally observed in close proximity of the gabbroic intrusions (Braga et al 2001(Braga et al , 2003.…”

Section: Continental Crustmentioning

confidence: 99%

Unravelling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins

Mohn

Manatschal

Müntener

et al. 2010

Int J Earth Sci (Geol Rundsch)

161

163

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The discovery of exhumed continental mantle and hyper-extended crust in present-day magma-poor rifted margins is at the origin of a paradigm shift within the research field of deep-water rifted margins. It opened new questions about the strain history of rifted margins and the nature and composition of sedimentary, crustal and mantle rocks in rifted margins. Thanks to the benefit of more than one century of work in the Alps and access to world-class outcrops preserving the primary relationships between sediments and crustal and mantle rocks from the fossil Alpine Tethys margins, it is possible to link the subsidence history and syn-rift sedimentary evolution with the strain distribution observed in the crust and mantle rocks exposed in the distal rifted margins. In this paper, we will focus on the transition from early to late rifting that is associated with considerable crustal thinning and a reorganization of the rift system. Crustal thinning is at the origin of a major change in the style of deformation from high-angle to lowangle normal faulting which controls basin-architecture, sedimentary sources and processes and the nature of basement rocks exhumed along the detachment faults in the distal margin. Stratigraphic and isotopic ages indicate that this major change occurred in late Sinemurian time, involving a shift of the syn-rift sedimentation toward the distal domain associated with a major reorganization of the crustal structure with exhumation of lower and middle crust. These changes may be triggered by mantle processes, as indicated by the infiltration of MOR-type magmas in the lithospheric mantle, and the uplift of the Briançonnais domain. Thinning and exhumation of the crust and lithosphere also resulted in the creation of new paleogeographic domains, the Proto Valais and Liguria-Piemonte domains. These basins show a complex, 3D temporal and spatial evolution that might have evolved, at least in the case of the Liguria-Piemonte basin, in the formation of an embryonic oceanic crust. The re-interpretation of the rift evolution and the architecture of the distal rifted margins in the Alps have important implications for the understanding of rifted margins worldwide, but also for the paleogeographic reconstruction of the Alpine domain and its subsequent Alpine compressional overprint.

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“…Ivrea Zone, Quick et al, 1995;External Liguride units, Montanini and Tribuzio, 2001) and mid-crust (e.g. Sondalo, Braga et al, 2001;Mont Collon, Monjoie et al, 2005). The intrusion of the basic melts was commonly associated with a significant process of crustal assimilation (Voshage et al, 1990;Sinigoi et al, 1994;Tribuzio et al, 1999), which hampers an accurate definition of their primary mantle melts.…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of Early Permian olivine-bearing cumulates and associated basalt dykes from Bocca di Tenda (Northern Corsica): Implications for post-collisional Variscan evolution

et al. 2009

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The sondalo gabbroic complex (central alps, Northern Italy): evidence for emplacement of mantle-derived melts into amphibolite-facies metapelites

Cited by 21 publications

References 14 publications

Rift-related inheritance in orogens: a case study from the Austroalpine nappes in Central Alps (SE-Switzerland and N-Italy)

Rift-related inheritance in orogens: a case study from the Austroalpine nappes in Central Alps (SE-Switzerland and N-Italy)

Unravelling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins

Petrogenesis of Early Permian olivine-bearing cumulates and associated basalt dykes from Bocca di Tenda (Northern Corsica): Implications for post-collisional Variscan evolution

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