scholarly journals Early Permian silicified floras from the Perdasdefogu Basin (SE Sardinia): comparison and bio-chronostratigraphic correlation with the floras of the Autun Basin (Massif central, France)

Geodiversitas ◽  
2011 ◽  
Vol 33 (1) ◽  
pp. 43-69 ◽  
Author(s):  
Jean Galtier ◽  
Ausonio Ronchi ◽  
Jean Broutin
Keyword(s):  
Early Permian ◽  
Massif Central

scholarly journals New Early Permian paleomagnetic results from the Brive basin (French Massif Central) and their implications for Late Variscan tectonics

2006 ◽  
Vol 95 (2) ◽  
pp. 306-317 ◽  
Author(s):  
Yan Chen ◽  
Bernard Henry ◽  
Michel Faure ◽  
Jean-François Becq-Giraudon ◽  
Jean-Yves Talbot ◽  
...  
Keyword(s):  
Early Permian ◽  
French Massif Central ◽  
Massif Central ◽  
Brive Basin

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.

Early Permian extensional shearing of an Ordovician granite: The Saint-Eutrope “C/S-like” orthogneiss (Montagne Noire, French Massif Central)

2012 ◽  
Vol 344 (8) ◽  
pp. 377-384 ◽  
Author(s):  
Pavel Pitra ◽  
Marc Poujol ◽  
Jean Van Den Driessche ◽  
Jean-Charles Poilvet ◽  
Jean-Louis Paquette
Keyword(s):  
Early Permian ◽  
French Massif Central ◽  
Massif Central ◽  
Montagne Noire

scholarly journals Carbon and Nitrogen Cycle Dynamic in Continental Late-Carboniferous to Early Permian Basins of Eastern Pangea (Northeastern Massif Central, France)

2021 ◽  
Vol 9 ◽  
Author(s):  
Mathilde Mercuzot ◽  
Christophe Thomazo ◽  
Johann Schnyder ◽  
Pierre Pellenard ◽  
François Baudin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Black Shales ◽  
Depositional Environments ◽  
Late Carboniferous ◽  
Type I ◽  
Early Permian ◽  
Massif Central ◽  
Carbon And Nitrogen ◽  
Rock Eval

Late Carboniferous to early Permian organic-rich sedimentary successions of late-orogenic continental basins from the northeastern Massif Central (France) coincide with both the Variscan mountain dismantling and the acme of the long-lasting Late Paleozoic Ice Age. Here, we investigate the carbon and nitrogen cycles in the newly dated sedimentary successions of the Decize–La Machine and Autun basins during these geodynamic and climate upheavals. The sedimentary organic matter has been analyzed through Rock-Eval pyrolysis, palynofacies and elemental and isotope geochemistry along cored-wells and outcropping sections, previously accurately defined in terms of paleo-depositional environments. Rock-Eval and palynofacies data have evidenced two origins of organic matter: a phytoplanktonic/bacterial lacustrine origin (Type I organic matter, organic δ13C values around −23.5‰), and a terrestrial origin (vascular land plants, Type III organic matter, organic δ13C values around −20‰), mixed in the deltaic-lacustrine sediments during background sedimentation (mean organic δ13C values around −22‰). Episodes of high organic matter storage, reflected by black shales and coal-bearing deposits (total organic carbon up to 20 and 70%, respectively) are also recognized in the successions, and are characterized by large negative organic carbon isotope excursions down to −29‰. We suggest that these negative isotope excursions reflect secondary processes, such as organic matter remineralization and/or secondary productivity varying under strict local controls, or possibly larger scale climate controls. At times, these negative δ13C excursions are paired with positive δ15N excursions up to +10‰, reflecting water column denitrification and anammox during lake-water stratification episodes. Together, these isotopic signals (i.e., low sedimentary organic δ13C associated with high bulk δ15N values) indicate periods of high primary productivity of surface waters, where nitrogen and carbon cycles are spatially decoupled. These local processes on the sedimentary isotope archives may partially blur our ability to directly reconstruct paleoclimate variations in such continental settings using only C and N isotopes. At last, we explore an organic δ13C-based mixing model to propose ways to disentangle autochthonous versus allochthonous origin of organic matter in lacustrine continental settings.

A new vertebrate Lagerstätte from the Lower Permian of France (Franchesse, Massif Central): palaeoenvironmental implications for the Bourbon-l'Archambault basin

2012 ◽  
Vol 183 (6) ◽  
pp. 509-515 ◽  
Author(s):  
J.-Sébastien Steyer ◽  
Sophie Sanchez ◽  
Pierre J. Debriette ◽  
Andrea M.F. Valli ◽  
François Escuille ◽  
...  
Keyword(s):  
Geographical Distribution ◽  
Aquatic Environment ◽  
First Record ◽  
Mass Mortality ◽  
Lower Permian ◽  
Early Permian ◽  
Massif Central

Abstract A new vertebrate locality from the Lower Permian (Cisuralian) of the Bourbon-l'Archambault basin (Massif Central, France) is reported and its associated flora and fauna preliminarily described. This locality corresponds to a mass mortality assemblage deposited in an aquatic environment. Interestingly, it has yielded hundreds of exceptionally well preserved seymouriamorph specimens, all referred to Discosauriscus austriacus. This exquisite assemblage corresponds to the first seymouriamorph Lagerstätte and the first record of D. austriacus outside the Boskovice basin in Czechia. It enlarges the geographical distribution of the species during the Early Permian, and has new palaeoenvironmental implications regarding the Palaeozoic Bourbon-l'Archambault basin.

The earliest ostracods from the Ordovician of the Prague Basin, Czech Republic

2014 ◽  
Vol 64 (4) ◽  
pp. 367-392 ◽  
Author(s):  
Karolína Lajblová ◽  
Petr Kraft
Keyword(s):  
Czech Republic ◽  
Bohemian Massif ◽  
Massif Central ◽  
Central European ◽  
Middle Ordovician ◽  
Prague Basin ◽  
Barrandian Area ◽  
Fossil Assemblages ◽  
European Variscides

Abstract The earliest ostracods from the Bohemian Massif (Central European Variscides) have been recorded from the Middle Ordovician of the Prague Basin (Barrandian area), in the upper Klabava Formation, and became an abundant component of fossil assemblages in the overlying Šarka Formation. Both early ostracod associations consist of eight species in total, representing mainly eridostracans, palaeocopids, and binodicopids. The revision, description, or redescription of all species and their distribution in the basin is provided. Their diversification patterns and palaeogeographical relationships to ostracod assemblages from other regions are discussed.

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