Structure of lamprophyres: a discriminant marker for Variscan and Alpine tectonics in the Argentera-Mercantour Massif, Maritime Alps
Item
Title (Dublin Core)
Structure of lamprophyres: a discriminant marker for Variscan and Alpine tectonics in the Argentera-Mercantour Massif, Maritime Alps
Description (Dublin Core)
Structural and microstructural analyses are carried out in two sites of the Argentera-Mercantour Massif, Valscura and Val du Haut Boréon, where swarms of lamprophyres intruded into Variscan migmatites and early Permian granitoids. Efforts aim at defining the structural relationships between lamprophyres and country rocks, and at constraining the structural and metamorphic evolution the dykes record. Mesoscale structural data are synthesised in geologic maps originally surveyed at 1/10 000 scale, supported by form-surface maps at 1/100 scale. The lamprophyres are magnesian, calc-alkalic to alkali-calcic, and metaluminous; they emplaced at very shallow crustal levels intersecting three generations of ductile structures in the host migmatites (D1, D2, D3). Epidote- and actinolite-bearing mineral assemblages result from late-intrusive hydrothermal circulation that has not affected the host rocks. Mylonitic shear zones of Alpine age (D4) are continuous through migmatites, granites, and lamprophyres: in these latter, they are supported by albite, actinolite, biotite, chlorite, epidote, phengite, and titanite. This detailed multi-scale structural analysis, coupled with major and trace elements geochemistry, highlights two main results: i) the lamprophyres, which post-date both the late- to post-collisional “high-Mg” and the “low-Mg” granitoids, reflect the last magmatic event in the Argentera-Mercantour Massif related to the Permian-Triassic lithospheric thinning; ii) the metamorphic assemblages that support the Alpine shear zones in the lamprophyres are consistent with the transition between the greenschist and amphibolite facies conditions.
Creator (Dublin Core)
Filippi Marco
Zanoni Davide
Gosso Guido
Lardeaux Jean-Marc
Verati Chrystèle
Spalla Maria Iole
Subject (Dublin Core)
external crystalline massifs
multiscale structural analysis
variscan deformation
alpine deformation and metamorphism
late- to post-variscan magmatism
high-k calc-alkaline lamprophyres
Geology
QE1-996.5
Publisher (Dublin Core)
EDP Sciences
Date (Dublin Core)
2019-01-01T00:00:00Z
Type (Dublin Core)
article
Identifier (Dublin Core)
1777-5817
10.1051/bsgf/2019014
https://doaj.org/article/fa26aef8c6d3471ebb4be3a7dd695f60
Source (Dublin Core)
BSGF - Earth Sciences Bulletin, Vol 190, p 12 (2019)
Language (Dublin Core)
EN
FR
Relation (Dublin Core)
https://www.bsgf.fr/articles/bsgf/full_html/2019/01/bsgf190010/bsgf190010.html
https://doaj.org/toc/1777-5817
Provenance (Dublin Core)
Journal Licence: CC BY