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Stéphanie Brichau Jean-Patrick Respaut Patrick Monié 《International Journal of Earth Sciences》2008,97(4):725-738
During the development of the Variscan orogeny, large amounts of granitic melt were produced, giving rise to the intrusion
of granitoids at different structural levels. Despite numerous studies, ages available from previous work on the Cévennes
granites remain largely imprecise. In order to better constrain the age and emplacement mode of these granites, we have combined
U–Pb dating on monazites and zircons and 40Ar/39Ar dating on biotites with petrological observations, major element chemical analysis and SEM zircon imaging on five samples
from the Aigoual–St Guiral–Liron and Mont Lozère granitic massifs. The results revealed that granitic intrusions and cooling
in Southern Cévennes occurred in a short time span at ∼306 Ma after the main episode of regional metamorphism. Petrological
and chemical data suggest that they result from a mixing between mantle-derived basic magmas (lamprophyres) and lower crust
acid magmas. At a regional scale the production of these melts occurred at the end of crustal thickening induced by nappe
stacking, at the same time as the late anatectic events recorded further north in the Velay dome and the granulite facies
metamorphism recorded in metasedimentary granulite enclaves brought up by Tertiary volcanoes of the Velay area (Bournac). 相似文献
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Françoise Roger Jean-Patrick Respaut Maurice Brunel Philippe Matte Jean-Louis Paquette 《Comptes Rendus Geoscience》2004,336(1):19-28
We present new U–Pb results on felsic Augen orthogneisses from the Axial Zone of the Montagne Noire (French Massif Central). The data indicate Ordovician ages, 456±3 and 450±6 Ma for two samples collected at ‘Pont-de-Larn’ and ‘Gorges d'Héric’, respectively. These ages are interpreted as the igneous emplacement age of the granitic protolith. To cite this article: F. Roger et al., C. R. Geoscience 336 (2004). 相似文献
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Olivier Maurel Jean-Patrick Respaut Patrick Monié Nicolas Arnaud Maurice Brunel 《Comptes Rendus Geoscience》2004,336(12):1091-1098
Zircon UPb dating by SIMS of the Mont-Louis granite yields an age of 305±5 Ma, intrepreted to reflect the igneous emplacement age of the massif. It is in agreement with the Hercynian syntectonic character of Pyrenees granite. 40Ar/39Ar on hornblende, biotite and K-feldspar permit, to estimate the massif cooling. A rapid temperature decrease (≈30 °C/Ma) is revealed from Westphalian to Late Stephanian, coeval with the emplacement of a laccolithe in the upper crust. Then, the cooling rate decreases to ≈1 °C/Ma. This would be consistent with a long time residence for the pluton from the Late Palaeozoic to the Early Cainozoic at 6–8 km depth. To cite this article: O. Maurel et al., C. R. Geoscience 336 (2004). 相似文献
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