Harmonisation et définition des unités lithostratigraphiques briançonnaises dans les nappes penniques du Valais

Sartori, Mario; Gouffon, Yves; Marthaler, Michel

doi:10.1007/s00015-006-1200-2

Cited by 46 publications

(93 citation statements)

References 9 publications

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“…these formations are absent in the other parts of the nappe (front and overturned limb) due to detachment from their substratum during Alpine deformation and can be identified now in the Préalpes Médianes rigides (trümpy 1955;sartori 1990;sartori & Marthaler 1994).…”

Section: Normal Limb Of the Siviez-mischabel Nappementioning

confidence: 96%

“…the normal limb of the siviez-Mischabel nappe has been well documented (sartori & thélin 1987; sartori 1990; thélin et al 1993) (Escher 1988;sartori 1990;thélin et al 1993;sartori et al 2006 (Marthaler 1984;, 1990: divided in two series in the barrhorn area; the barrhorn series and the toûno series. these formations are absent in the other parts of the nappe (front and overturned limb) due to detachment from their substratum during Alpine deformation and can be identified now in the Préalpes Médianes rigides (trümpy 1955;sartori 1990;sartori & Marthaler 1994).…”

Section: Normal Limb Of the Siviez-mischabel Nappementioning

confidence: 98%

“…this super-nappe was separated into distinct tectonic units (Escher 1988;sartori et al 2006), from bottom to top: (a) the Houillère zone, (b) the ruitor zone, (c) the siviez-Mischabel nappe and (d) the Mont-Fort nappe (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…1. Location of the studied area (black box) on the structural map of the Penninic units, modified after Escher (1988) andsartori et al (2006).…”

Section: Introductionmentioning

confidence: 99%

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Lithostratigraphy and U-Pb zircon dating in the overturned limb of the Siviez-Mischabel nappe: a new key for Middle Penninic nappe geometry.

et al. 2008

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Detailed field work and zircon analysis have improved the knowledge of the lithostratigraphy at the base of the siviez-Mischabel nappe in the Mattertal (st-Niklaus-törbel area). they confirm the existence of an overturned limb and clarify the structure of the st-Niklaus syncline. the following formations can be observed:• Polymetamorphic gneisses; composed of paragneisses, amphibolites and micaschists (bielen Unit, pre-Ordovician).• Fine-grained, greyish quartzite and graywacke with kerogen-rich horizons (törbel Formation, presumed carboniferous).• Green or white micaschists characterized by brown carbonate spots associated with white conglomeratic quartzites (Moosalp Formation, Early Permian). • Massive, green or white, fine grained, microconglomeratic or conglomeratic quartzites with characteristic pink quartz pebbles (bruneggjoch Formation, Late Permian-Early triassic).this coherent overturned sequence can be observed from the st-Niklaus area to the Moosalp pass to the north. Detailed mapping revealed that the st-Niklaus syncline is symmetrical and connects the overturned limb of the siviez-Mischabel nappe to the normal series of the Upper stalden zone. U-Pb zircon geochronology on magmatic and detrital zircons allowed constraining ages of these formations. Detrital zircons display ages ranging from 2900 ± 50 to 520 ± 4 Ma in the törbel Formation, and from 514 ± 6 to 292 ± 9 Ma in the Moosalp Formation. In addition, the Permian randa orthogneiss is intrusive into the polymetamorphic gneisses and into the Permo-carboniferous metasediments of the overturned limb of the siviez-Mischabel nappe. this revision clarified also the lithostratigraphy of the nearby and subjacent Lower stalden zone composed of an overturned limb with Permo-carboniferous formations. this has critical implications for the tectonic setting of the nappes in the region, speaking for few recumbent folds with well preserved normal and overturned limbs instead of a succession of imbricate thrust sheets in a normal stratigraphic position.

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Section: Normal Limb Of the Siviez-mischabel Nappementioning

confidence: 96%

Section: Normal Limb Of the Siviez-mischabel Nappementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

“…1. Location of the studied area (black box) on the structural map of the Penninic units, modified after Escher (1988) andsartori et al (2006).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Lithostratigraphy and U-Pb zircon dating in the overturned limb of the Siviez-Mischabel nappe: a new key for Middle Penninic nappe geometry.

et al. 2008

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“…The rock type present is very large, from Cambrian polycyclic basements to Mesozoic and Cenozoic sedimentary covers (Sartori et al, 2006) of the Helvetic, Penninic and Austro-Alpine domains (Trümpy, 1980). Furthermore, large areas are covered by quaternary deposits that are fluvioglacial deposits, colluvial fans or moraines.…”

Section: Detection Of Block Release Areasmentioning

confidence: 99%

Rockfall hazard and risk assessments along roads at a regional scale: example in Swiss Alps

Michoud

Derron

Horton

et al. 2012

Nat. Hazards Earth Syst. Sci.

126

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Abstract. Unlike fragmental rockfall runout assessments, there are only few robust methods to quantify rock-massfailure susceptibilities at regional scale. A detailed slope angle analysis of recent Digital Elevation Models (DEM) can be used to detect potential rockfall source areas, thanks to the Slope Angle Distribution procedure. However, this method does not provide any information on block-release frequencies inside identified areas. The present paper adds to the Slope Angle Distribution of cliffs unit its normalized cumulative distribution function. This improvement is assimilated to a quantitative weighting of slope angles, introducing rock-mass-failure susceptibilities inside rockfall source areas previously detected. Then rockfall runout assessment is performed using the GIS-and process-based software Flow-R, providing relative frequencies for runout. Thus, taking into consideration both susceptibility results, this approach can be used to establish, after calibration, hazard and risk maps at regional scale. As an example, a risk analysis of vehicle traffic exposed to rockfalls is performed along the main roads of the Swiss alpine valley of Bagnes.

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The Grand St Bernard‐Briançonnais Nappe System and the Paleozoic Inheritance of the Western Alps Unraveled by Zircon U‐Pb Dating

et al. 2017

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The continental crust involved in the Alpine orogeny was largely shaped by Paleozoic tectono‐metamorphic and igneous events during oblique collision between Gondwana and Laurussia. In order to shed light on the pre‐Alpine basement puzzle disrupted and reamalgamated during the Tethyan rifting and the Alpine orogeny, we provide sensitive high‐resolution ion microprobe U‐Pb zircon and geochemical whole rock data from selected basement units of the Grand St Bernard‐Briançonnais nappe system in the Western Alps and from the Penninic and Lower Austroalpine units in the Central Alps. Zircon U‐Pb ages, ranging from 459.0 ± 2.3 Ma to 279.1 ± 1.1 Ma, provide evidence of a complex evolution along the northern margin of Gondwana including Ordovician transtension, Devonian subduction, and Carboniferous‐to‐Permian tectonic reorganization. Original zircon U‐Pb ages of 371 ± 0.9 Ma and 369.3 ± 1.5 Ma, from calc‐alkaline granitoids of the Grand Nomenon and Gneiss del Monte Canale units, provide the first compelling evidence of Late Devonian orogenic magmatism in the Alps. We propose that rocks belonging to these units were originally part of the Moldanubian domain and were displaced toward the SW by Late Carboniferous strike‐slip faulting. The resulting assemblage of basement units was disrupted by Permian tectonics and by Mesozoic opening of the Alpine Tethys. Remnants of the Moldanubian domain became either part of the European paleomargin (Grand Nomenon unit) or part of the Adriatic paleomargin (Gneiss del Monte Canale unit), to be finally accreted into the Alpine orogenic wedge during the Cenozoic.

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Harmonisation et définition des unités lithostratigraphiques briançonnaises dans les nappes penniques du Valais

Cited by 46 publications

References 9 publications

Lithostratigraphy and U-Pb zircon dating in the overturned limb of the Siviez-Mischabel nappe: a new key for Middle Penninic nappe geometry.

Lithostratigraphy and U-Pb zircon dating in the overturned limb of the Siviez-Mischabel nappe: a new key for Middle Penninic nappe geometry.

Rockfall hazard and risk assessments along roads at a regional scale: example in Swiss Alps

The Grand St Bernard‐Briançonnais Nappe System and the Paleozoic Inheritance of the Western Alps Unraveled by Zircon U‐Pb Dating

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