Dykes and Pipes of Remobilized Cornieules within the Cornieule Evaporitic-Complex of the Mont Jovet Area (Northwestern French Alps)

Fudral, Serge; Chang-yi, LU; Paillet, André

doi:10.3166/ga.23.195-205

Cited by 4 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, in contrast to the map of Michard (1967), we defined tectonic contacts by separating continental sedimentary sequences that include Triassic carbonates at their base from juxtaposed oceanic sequences that include serpentinites, despite of the apparent structural and metamorphic continuity of the units. Such tectonic contacts are frequently well-marked by lenses of serpentinites or cargneules (also spelled cornieules = evaporitic tectonic breccias; Masson, 1972;Fudral et al, 2010). Admittedly, where such markers are lacking, tracking a tectonic limit between oceanderived Schistes lustrés (Cretaceous) and Schistes lustrés (Jurassic) that are part of the Prepiemonte sedimentary sequence remains uncertain in places.…”

Section: Methodology For Drawing a New Structural Mapmentioning

confidence: 99%

See 1 more Smart Citation

The Maira-Sampeyre and Val Grana Allochthons (south Western Alps): review and new data on the tectonometamorphic evolution of the Briançonnais distal margin

et al. 2022

View full text Add to dashboard Cite

Here we describe the structure, the high-pressure, low-temperature (HP-LT) metamorphism and tectonic evolution of the Briançonnais distal margin units from the south Western Alps. The studied area extends southwest of the Dora-Maira (U)HP basement units and east-southeast of the classical Briançonnais nappes. A new structural map accompanied by geological profiles shows the thrusting of the oceanic nappes (Monviso and Queyras units) onto the distal Briançonnais units (D1 and D2 late Eocene deformation phases) under blueschist-facies conditions. Subsequent deformation during the Early Oligocene (D3 deformation phase) took place under greenschist-facies conditions and was associated with back-folding and -thrusting in the units overlying the Dora-Maira massif and with exhumation related to normal reactivation of former thrusts within the latter massif. Two large cover units, detached from their former distal Briançonnais basement, are redefined as the Maira-Sampeyre and Val Grana Allochthons (shortly: Maira-Grana Allochthons = MGA) including, (i) the Val Maira-Sampeyre unit involving Lower and Middle Triassic formations, seemingly detached from the Dora-Maira units during the subduction process, and (ii) the Val Grana unit with Middle-Upper Triassic and Early-Middle Jurassic formations, which was probably detached from the Maira-Sampeyre unit and correlates with the “Prepiemonte units” known from the Ligurian Alps to the Swiss Prealps. Three major shear zones involving tectonic mélanges of oceanic and continental rocks at the base of the Val Grana, Maira-Sampeyre and Dronero units testify to an early phase of exhumation within the subduction channel in front of the Adria plate. We present a new metamorphic map based on published and new petrological data, including new thermometric data obtained by Raman spectroscopy of carbonaceous material (RSCM). The TRSCM values range from ~ 400 °C to > 500 °C, going from the most external Val Grana unit and overlying Queyras schists to the uppermost Dora-Maira unit. During the Late Triassic, the width of the Briançonnais s.l. domain can be restored at ~ 100 km, whereas it reached ~ 150 km after the Jurassic rifting. A significant, second rifting event affected the Briançonnais domain during the Late Cretaceous-Paleocene, forming the Longet-Alpet chaotic breccias, which deserve further investigations.

show abstract

Section: Methodology For Drawing a New Structural Mapmentioning

confidence: 99%

“…The Pradleves cargneule zone (Fig. 5) could result from the hydraulic extrusion (Fudral et al, 2010) of the Triassic evaporitic rocks (brecciated in the sole of the Val Grana unit) between the Pradleves-Rocca Caire and Valgrana D 3 anticlines.…”

Section: Deformation Phases: From Early Thrusting To Backfoldingmentioning

confidence: 99%

The Maira-Sampeyre and Val Grana Allochthons (south Western Alps): review and new data on the tectonometamorphic evolution of the Briançonnais distal margin

et al. 2022

View full text Add to dashboard Cite

show abstract

“…The origin of the cornieules is not very clear, however; they may have been partially re-mobilized at the tectonic contact and thus, in the terminology of some authors (e.g. Alberto et al 2007;Fudral et al 2010), they might be pseudo-cornieules.…”

Section: The Barmet Shear Zonementioning

confidence: 99%

Internal geometry of the central Sesia Zone (Aosta Valley, Italy): HP tectonic assembly of continental slices

Giuntoli

Engi

2016

Swiss J Geosci

View full text Add to dashboard Cite

Detailed field mapping reveals that the Sesia Zone is subdivided into two complexes with the Barmet Shear Zone (BSZ) outlining the tectonic contact between them. This greenschist-facies contact reflects a metamor-phic gap between the Internal Complex (eclogite facies, eclogitic micaschists dominant) and the External Complex (epidote blueschist facies). The BSZ comprises a wedge shape area in which fragments and slices of orthogneiss and paragneiss are wrapped by siliceous dolomite marbles displaying a mylonitic foliation. Conspicuous cornieules and high pressure breccias occur along this contact. We propose that the eclogite facies Internal Complex is sub-divided into three basement units, called sheets, delimited by discontinuous metasedimentary trails of probable Mesozoic age. Thin monocyclic bands thus separate kilo-metre scale polycyclic sheets. The External Complex comprises three epidote blueschist facies sheets of com-parable size, which are separated by lenses retaining a pre-Alpine high temperature imprint. These weakly overprinted fragments (parts of the classically termed 2DK zone) are aligned along greenschist facies shear zones that separate the gneissic sheets. The BSZ, with a wedge rich in meta-sediments, chiefly siliceous dolomite marbles, is a key element in which fragmentation and reworking of materials from the internal and external complexes are evident. A carbonate breccia occurs in this shear zone, with clasts displaying a HP foliation randomly oriented in a ductile carbonate matrix. Siliceous dolomite marbles appear to have acted as lubricants to accommodate deformation related to the juxtaposition of the two basement complexes during exhumation. We propose a model of the Sesia Zone, with the BSZ as the thrust responsible for the juxtaposition of eclogite facies rocks of the Internal Complex on top of epidote blueschist facies rocks of the External Complex. The two complexes were already assembled when this shear zone became active. The entire stack was finally rotated (40 60°) during the Vanzone Phase.

show abstract

Salt Dissolution and Pointers to Vanished Evaporites: Karst, Breccia, Nodules and Cement

Warren

2016

Evaporites

View full text Add to dashboard Cite

Dykes and Pipes of Remobilized Cornieules within the Cornieule Evaporitic-Complex of the Mont Jovet Area (Northwestern French Alps)

Cited by 4 publications

References 20 publications

The Maira-Sampeyre and Val Grana Allochthons (south Western Alps): review and new data on the tectonometamorphic evolution of the Briançonnais distal margin

The Maira-Sampeyre and Val Grana Allochthons (south Western Alps): review and new data on the tectonometamorphic evolution of the Briançonnais distal margin

Internal geometry of the central Sesia Zone (Aosta Valley, Italy): HP tectonic assembly of continental slices

Salt Dissolution and Pointers to Vanished Evaporites: Karst, Breccia, Nodules and Cement

Contact Info

Product

Resources

About