La Zona Sesia-Lanzo e l'evoluzione tettonico-metamorfica delle Alpi nordoccidentali interne: quarant'anni dopo

Piaz, G. V. Dal

doi:10.3301/rol.2015.167

Cited by 33 publications

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“…The latter consists largely of Paleozoic continental basement recording Alpine metamorphism at blueschist to eclogite facies conditions (Dal Piaz et al, 1972;Compagnoni et al, 1977). The Sesia Zone is traditionally subdivided into Eclogitic Micaschist Complex, which experienced P N 1.8 GPa (Konrad-Schmolke et al, 2011), Second Dioritic-Kinzigitic Zone and Gneiss Minuti Complex, where only blueschist facies metamorphic assemblages have been reported (Fig.…”

Section: Tectono-metamorphic Evolution Of the Western Alpsmentioning

confidence: 99%

“…Based on Alpine metamorphism, presence of major bounding shear zones and type of preAlpine basement, the Sesia Zone is generally subdivided into three major units, labeled Eclogitic Micaschist Complex (EMC), Second Dioritic-Kinzigitic Zone (2DK), Gneiss Minuti Complex (GM) and the minor Rocca Canavese Unit (Dal Piaz et al, 1972;Compagnoni et al, 1977;Pognante, 1989). Rare Mesozoic meta-sediments have so far been observed only in the EMC (Venturini et al, 1994) and GM (Gosso et al, 1979;Minnigh, 1979;Pognante et al, 1987).…”

Section: Sesia Zonementioning

confidence: 99%

“…Originally, this term was adopted to indicate a tectonic unit consisting predominantly of Permian granitoids intruded in a pre-existing basement, then affected by pervasive Alpine reequilibration under blueschist to greenschist facies conditions (Dal Piaz et al, 1972;Compagnoni et al, 1977;Cortiana et al, 1998). The Gneiss Minuted Complex has alternativey been considered as separated from the EMC by an Alpine 'transition zone' (Dal Piaz et al, 1972) or shear zone (Williams and Compagnoni, 1983;Venturini, 1995) or as originally intrusive into the EMC Babist et al, 2006). Studies carried out in the south-western part of the Sesia Zone showed that the orthogneisses are locally directly in contact with micaschists, carbonate-bearing schists and Mn-rich quartzites, interpreted as Mn-bearing metacherts of probable Middle Jurassic age (Minnigh, 1979;Pognante et al, 1987).…”

Section: Sesia Zonementioning

confidence: 99%

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Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Beltrando

Manatschal

Mohn

et al. 2014

Earth-Science Reviews

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118

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Magma-poor rifted margins are being increasingly recognized in present-day Atlantic-type systems. However, findings of fossil areas floored by exhumed mantle or hyper-extended crust are comparatively rare within orogenic belts that were originated through the inversion of pre-existing rifted margins. This discrepancy may be due to the common reactivation of lithological contacts during subduction/orogeny, potentially masking pre-orogenic relationships, and, most importantly, to the frequent lack of a preorogenic layer-cake architecture, hindering retro-deformation of multiply deformed tectonic units. This study outlines a methodology to detect sections of magma-poor, hyper-extended rifted margins without a layer-cake architecture in multiply deformed/metamorphosed terrains. This approach is defined by comparison to well studied examples of fossil analogues preserved in weakly deformed parts of Alpine orogens. In the latter domains, continental basement and hydrated peridotites were exhumed at the basin floor during Jurassic rifting along long-offset detachment systems. Extensional geometries locally resulted in tectonic sampling of laterally discontinuous slivers of allochthonous continental basement and pre-rift sediments from the hanging wall blocks. Lithostratigraphic associations consisting of continental basement rocks directly juxtaposed with syn-to post-rift meta-sediments and/or serpentinized subcontinental mantle are widespread within sections of Alpine-type orogenic belts that underwent high-to ultra-high-pressure metamorphism. However, similar associations may arise from a variety of processes other than rift-related lithospheric thinning in magma-poor environments, including subduction mélange dynamics or deposition of sedimentary mélanges along convergent/divergent margins. The partial preservation of rift-related lithostratigraphic associations may still be assessed, despite the lack of biostratigraphic evidence, by (1) the consistency of the lithostratigraphic architecture over large areas, despite pervasive Alpine deformation, which rules out chaotic mixing during subduction/ exhumation, (2) the presence of clasts of basement rocks in the neighboring meta-sediments, indicating the original proximity of the different lithologies, (3) evidence of brittle deformation in continental basement and ultramafic rocks pre-dating Alpine metamorphism, indicating that they were juxtaposed by fault activity prior to the deposition of post-rift sediments, and (4) the similar Alpine tectono-metamorphic evolution of ophiolites, continental basement and meta-sediments. A re-assessment of basement-cover relationships in...

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Section: Tectono-metamorphic Evolution Of the Western Alpsmentioning

confidence: 99%

Section: Sesia Zonementioning

confidence: 99%

Section: Sesia Zonementioning

confidence: 99%

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Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Beltrando

Manatschal

Mohn

et al. 2014

Earth-Science Reviews

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118

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“…The complexity of Piemonte geology is the result of a continuous geodynamic process which, since the Rhaetian-Hettangian, led to the formation of two continental 'passive' margins: the 'Palaeo-European Margin' and the 'Palaeo-Adriatic Margin', and two oceanic zones: the Liguria-Piemonte Domain and the Valais Domain (Bernoulli & Jenkins, 2009;Bertotti, Picotti, Bernoulli, & Castellarin, 1993;Dal Piaz, 1974;1999;Dal Piaz, Bistacchi, & Massironi, 2003;Dal Piaz, Hunziker, & Martinotti, 1972;Dewey & Bird, 1970;Dewey, Pitman, Ryan, & Bonnin, 1973;Handy, Schmid, Bousquet, Kissling, & Bernoulli, 2010;Mohn, Manatschal, Müntener, Beltrando, & Masini, 2010;Sturani, 1975;Trumpy, 2001). Since the Late Cretaceous, the European and Adriatic continental plate margins began to converge (Le Pichon, 1968) inducing the subduction of the interposed oceanic lithosphere.…”

Section: The Alps-apennines Orogenic Systemmentioning

confidence: 99%

Geology of Piemonte region (NW Italy, Alps–Apennines interference zone)

et al. 2017

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The geological map of Piemonte Region (Italy) is a graphic representation of the geology of the region, grounded on a large geodatabase, that can be also browsed as an interactive scalable map (GeoPiemonte Map) using a WebGIS application. The Map, produced at 1:250,000 scale, is the first original release of the 'GeoPiemonte Map' project. The geological data represented on the map derive from a thorough revision of available geological maps and literature, integrated with unpublished original data. The revision and harmonisation of existing and new data have been based on explicit criteria used for the classification of geologic units and their representation on the Map. These criteria firstly aimed at providing a lithostratigraphic, hierarchic subdivision of Piemonte geologic units and describing them using shared concepts and vocabularies, consistent with IUGS Descriptive Standards for the Geosciences. ARTICLE HISTORY

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“…The Sesia-Lanzo Zone (SLZ) represents the largest portion ( ̴ 90 × 20 km) of Austroalpine continental crust that has been eclogized during the Alpine subduction and now exposed in the axial zone of the Western Alps (Babist, Handy, Konrad-Schmolke, & Hammerschmidt, 2006;Compagnoni et al, 1977;Dal Piaz, Hunziker, & Martinotti, 1972;Delleani et al, 2013;Lardeaux, 2014;Manzotti, Ballèvre, Zucali, Robyr, & Engi, 2014;Regis et al, 2014;Venturini, Martinotti, Armando, Barbero, & Hunziker, 1994;Zucali et al, 2002). The SLZ is bounded by rocks of the Penninic domain to the northwest, and the Canavese Line (Periadriatic Line (PL)) to the southeast, which separates the SLZ from the Southern Alps (Figure 1(A)).…”

Section: Geologic Outlinementioning

confidence: 99%

Analysis of fabric evolution and metamorphic reaction progress at Lago della Vecchia-Valle d’Irogna, Sesia-Lanzo Zone, Western Alps

et al. 2017

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The Lago della Vecchia-Valle d'Irogna rocks are part of the Eclogitic Micaschists Complex (EMC) of the Sesia-Lanzo Zone, western Austroalpine domain. The 1:10,000 scale map includes metaintrusive, minor micaschist, banded gneiss, and metabasic boudins. The multiscale structural analysis reveals successive magmatic and tectono-metamorphic stages: during M0 the metaintrusive protoliths emplaced; D1 took place under eclogite-facies conditions; during D2 stage, a pervasive foliation developed under retrograde blueschist-facies conditions; D3-D4 and D5 structures developed under greenschist-facies conditions; during M6 andesitic dykes intruded. The mapped degree of fabric evolution (FE) and metamorphic transformation (MT) related to D2-foliation shows that the MT was not only controlled by bulk rock and mineral compositions, but also by FE. The development of a pervasive blueschist-facies D2-foliation is in contrast with the eclogitic dominant fabric generally recorded in the EMC. This difference suggests that FE and MT are potentially responsible for km-scale heterogeneities in the tectono-metamorphic record.ARTICLE HISTORY

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La Zona Sesia-Lanzo e l'evoluzione tettonico-metamorfica delle Alpi nordoccidentali interne: quarant'anni dopo

Cited by 33 publications

References 0 publications

Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Geology of Piemonte region (NW Italy, Alps–Apennines interference zone)

Analysis of fabric evolution and metamorphic reaction progress at Lago della Vecchia-Valle d’Irogna, Sesia-Lanzo Zone, Western Alps

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