Geological map of the middle Orco Valley, Western Italian Alps

Gasco, Ivano; Gattiglio, Marco

doi:10.4113/jom.2010.1121

Cited by 9 publications

(11 citation statements)

References 10 publications

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“…13d). Detailed mapping along the more southerly located Orco Valley, instead, reveals that the Paleozoic basement/Mesozoic meta-sediment interface is deformed by all folding stages detected in the field (Gasco and Gattiglio, 2010). Importantly, the three fold generations that have been recognized were entirely developed along the exhumation path of this tectono-metamorphic unit (Gasco et al, 2009), providing further evidence that structural analyses alone cannot univocally prove/disprove earlier juxtaposition during early-subduction dynamics.…”

Section: Sesia Zonementioning

confidence: 91%

“…Importantly, calcschists associated with Paleozoic basement host thick micaschist layers and, more rarely, dm-sized meta-granitoid clasts ( Fig. 13f; Gasco and Gattiglio, 2010), indicating a significant terrigenous input, hinting at original proximity of exhumed basement rocks. In specific circumstances, transitional contacts between leucocratic gneisses and calcschists over a thickness of 10 cm have been interpreted as primary sedimentary contacts between altered/ re-sedimented basement and calcschists or as gradual transitions between meta-arkose layers and calcschists (Gasco and Gattiglio, 2010).…”

Section: Sesia Zonementioning

confidence: 99%

“…13f; Gasco and Gattiglio, 2010), indicating a significant terrigenous input, hinting at original proximity of exhumed basement rocks. In specific circumstances, transitional contacts between leucocratic gneisses and calcschists over a thickness of 10 cm have been interpreted as primary sedimentary contacts between altered/ re-sedimented basement and calcschists or as gradual transitions between meta-arkose layers and calcschists (Gasco and Gattiglio, 2010). These observations suggest that the protoliths of the Gneiss Minuti Complex were regionally exhumed at the bottom of the Alpine Tethys, where they were locally overlain by Mn-rich cherts and calcschists, occasionally reworking the underlying continental basement.…”

Section: Sesia Zonementioning

confidence: 99%

“…Therefore, this paper is devoted to outlining a methodology to detect remnants of magma-poor hyper-extended rifted margins lacking a layer-cake architecture in highly deformed/metamorphosed terrains. The proposed approach is illustrated for the NorthWestern Alps and Corsica case studies, where both hyper-extended crustal domains (Ferrando et al, 2004;Gasco and Gattiglio, 2010;Beltrando et al, 2013) and areas floored by exhumed mantle (e.g. Lemoine et al, 1987;Dal Piaz, 1999;Beltrando et al, 2010a;Vitale Brovarone et al, 2011a;Beltrando et al, 2012;Meresse et al, 2012;) have been identified.…”

Section: Introductionmentioning

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

121

104

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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: Sesia Zonementioning

confidence: 91%

Section: Sesia Zonementioning

confidence: 99%

Section: Sesia Zonementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

121

104

View full text Add to dashboard Cite

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“…Provided that the correlations between Broillot unit and Combin unit on the one hand, and between Bardonney and Zermatt-Saas unit on the other hand are considered convincing (Beltrando et al, 2008), this study points to Ring, 1995;Reddy et al, 2003Reddy et al, , 1999Wheeler et al, 2001), would not be applicable to the Urtier area. However, these anomalous geometrical relationships appear to be a singularity, because in other areas south of Aosta Valley, a nappe stacking coinciding with that proposed north of Aosta Valley (i.e., Combin overthrusted over Zermatt-Saas) is described (Gasco & Gattiglio, 2010;Gasco, Gattiglio, & Borghi, 2009;Gasco, Gattiglio, & Borghi, 2013).…”

Section: Structural Evolutionmentioning

confidence: 95%

Nappe stack of Piemonte–Ligurian units south of Aosta Valley: New evidence from Urtier Valley (Western Alps)

Ellero

Loprieno²

2017

Geological Journal

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New results of structural and lithostratigraphic investigations performed in the Urtier Valley, located south of Aosta Valley at the northern flank of the Gran Paradiso Massif, shed new light on the nappe stack architecture of the Western Alps. Two distinct Piemonte–Ligurian units were recognized in the area: (a) the blueschist facies Broillot unit, with a well‐preserved lithostratigraphic succession that includes ophiolites and their metasedimentary cover and (2) the eclogitic Bardonney unit with clasts and/or slices of ophiolites embedded in a carbonate/quarzitic and/or metabasic matrix. Three major deformation stages have been recognized (D1, D2, and D3). D1 phase occurred during the peak metamorphic conditions (i.e., eclogite or blueschist facies). D2 and D3 phases are related to multistage exhumation processes, from early stacking to late refolding of former nappe contacts. Despite the intensity of deformation and metamorphism, the original lithostratigraphic succession of the Broillot unit allowed us to use a lithostratigraphic approach to reconstruct the structures in the study area. For the first time, differences in the nappe stack exposed south and north of the Aosta Valley are reported. In fact, contrary to what is observed in the north, the eclogitic units exposed in the Urtier Valley lay above and not below the blueschist units. A new model for the tectonic evolution, which ranges from stages of subduction to large‐scale nappe refolding, is proposed. It is able to explain the difference in the architecture of the north and south of the Aosta Valley.

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Robust Linear Regression-Based GIS Technique for Modeling the Processing Time at Tourism Destinations

Ali

Esztergár-Kiss

2022

HCI in Mobility, Transport, and Automotive Systems

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Geological map of the middle Orco Valley, Western Italian Alps

Cited by 9 publications

References 10 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

Nappe stack of Piemonte–Ligurian units south of Aosta Valley: New evidence from Urtier Valley (Western Alps)

Robust Linear Regression-Based GIS Technique for Modeling the Processing Time at Tourism Destinations

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