Extensional ductile tectonics of the Sioule metamorphic series (Variscan French Massif Central)

1993 ◽  
Vol 82 (3) ◽  
pp. 461-474 ◽  
Author(s):  
M. Faure ◽  
J. Grolier ◽  
J. Pons
Keyword(s):  
French Massif Central ◽  
Massif Central ◽  
Metamorphic Series

Thermal maturation and exhumation of a middle orogenic crust in the Livradois area (French Massif Central)

2011 ◽  
Vol 182 (1) ◽  
pp. 5-24 ◽  
Author(s):  
Véronique Gardien ◽  
Olivier Vanderhaeghe ◽  
Nicolas Arnaud ◽  
Alain Cocherie ◽  
Marion Grange ◽  
...  
Keyword(s):  
Final Stage ◽  
Crustal Melting ◽  
Early Permian ◽  
French Massif Central ◽  
Rapid Cooling ◽  
Massif Central ◽  
Upper Carboniferous ◽  
Peak Metamorphism ◽  
Metamorphic Series ◽  
Granitic Dome

AbstractUpper Carboniferous heating and melting of the middle orogenic crust associated with the emplacement of syntectonic granitoids are documented in the Upper Gneissic Unit of the Livradois area (central part of the French Massif Central). Crustal melting post-dates peak metamorphism conditions (800-625°C, 10-8 kb) dated at 360 ± 4 Ma (U-Th-Pb on monazite). The P-T evolution of the metamorphic series indicates that Barrovian metamorphism was followed by a decompression (from 10 ± 1 kbar to 6 ± 1 kbar) associated with either a decrease in temperature in the southern part of the series or with an increase in temperature (of about 150°C) in the northern part of the series. This evolution records the first step of the exhumation of the series coeval with granitoids intrusion, of which the emplacements were dated at 315 ± 4 and 311 ± 18 Ma (U-Pb on zircon). The final stage of the exhumation is associated with an isobaric cooling of the whole series. Similarity of 40Ar/39Ar ages for biotite in the paragneisses (307-300 Ma) and K-feldspar in the granitoids (306-300 Ma) document rapid cooling for this stage. Moreover dextral reverse mylonites, at the border and the northern part of the metamorphic series indicate north-south compression coeval with the unroofing of the series. Youngest 40Ar-39Ar ages on K-feldspar (274.6 ± 5 Ma) combined with normal shearing in mylonites limiting the Carboniferous Brassac-les-Mines basin document the late Carboniferous-early Permian stage of extension coeval with the upwelling of the Velay granitic dome.

Deciphering orogeny: a metamorphic perspective Examples from European Alpine and Variscan belts

2014 ◽  
Vol 185 (5) ◽  
pp. 281-310 ◽  
Author(s):  
Jean-Marc Lardeaux
Keyword(s):  
Regional Development ◽  
Western Alps ◽  
Temporal Data ◽  
French Massif Central ◽  
Massif Central ◽  
Metamorphic History ◽  
Variscan Metamorphism ◽  
Geochemical Constraints ◽  
Metamorphic Series

AbstractIn this paper we review and discuss, in a synthetic historical way, the main results obtained on Variscan metamorphism in the French Massif Central. First, we describe the pre-orogenic architecture of the French Massif Central on the base of available lithostratigraphic and geochemical constraints. Second, we portray the progressive metamorphic evolution through time and space with the presentation of 6 metamorphic maps corresponding to critical orogenic periods, namely 430–400 Ma, 400–370 Ma, 370–360 Ma, 360–345 Ma, 340–325 Ma and 320–290 Ma. We discuss the role of multiple subductions in orogeny, the metamorphic effects of continental collision (i.e. regional development of intermediate-pressure metamorphic series) as well as the links between post-thickening tectonics and the regional development of low-pressure metamorphic series coeval with crustal partial melting. As it was the case for the western Alps, we emphasize the lack of temporal data on high-pressure/low-temperature metamorphic rocks as well as the uncertainties on the sizes of rock units that have recorded the same metamorphic history (i.e. coherent P-T-t/deformation trajectories). Finally, we underline the main differences and similarities between the metamorphic evolutions of the western Alps and the French Massif Central.

Evaluating Holocene natural hazards in the French Massif Central from a regional lake sediment approach

2021 ◽  
Author(s):  
E. Chapron ◽  
A. Foucher ◽  
L. Chassiot ◽  
W. Fleurdeus ◽  
V. Arricau ◽  
...  
Keyword(s):  
Natural Hazards ◽  
Lake Sediment ◽  
French Massif Central ◽  
Massif Central

Sellaphora labernardierei (Sellaphoraceae, Bacillariophyta), a new epilithic species from French spring and four new combinations within the genus Sellaphora

Phytotaxa ◽  
2016 ◽  
Vol 260 (3) ◽  
pp. 235 ◽  
Author(s):  
AUDE BEAUGER ◽  
CARLOS E. WETZEL ◽  
OLIVIER VOLDOIRE ◽  
ALEXANDRE GARREAU ◽  
LUC ECTOR
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Central Area ◽  
Mineral Waters ◽  
New Combinations ◽  
French Massif Central ◽  
Small Species ◽  
Massif Central ◽  
Floristic Survey ◽  
Scanning Electron

During a floristic survey of freshwater springs in the French Massif Central region, a new Sellaphora species (Bacillariophyceae) was found and is hereby described: Sellaphora labernardierei sp. nov. This new small species, with linear to linear-elliptical valves, slightly inflated in the middle, is formally described using light and scanning electron microscopy. The species has a single H-shaped chloroplast and striae usually biseriate tending to be uniseriate near the centre of the valve. The valve dimensions, the valve, pole and central area shapes, and the striae density and pattern allow their separation from similar taxa belonging to the genera Eolimna, Naviculadicta and Sellaphora. The ecological preferences of Sellaphora labernardierei are mineral waters with high nitrate concentrations. The examination of similar taxa belonging to the genera Eolimna and Naviculadicta and their characteristics lead to propose four new combinations of Sellaphora species.

scholarly journals Tephras in lacustrine sediments of the Sarliève marsh (French Massif Central): age and preservation

2006 ◽  
Vol 338 (16) ◽  
pp. 1141-1149 ◽  
Author(s):  
Agathe Fourmont ◽  
Jean-Jacques Macaire ◽  
Jean-Gabriel Bréhéret ◽  
Jacqueline Argant ◽  
Béatrice Prat ◽  
...  
Keyword(s):  
Lacustrine Sediments ◽  
French Massif Central ◽  
Massif Central
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