UPb emplacement and 40Ar/39Ar cooling ages of the eastern Mont-Louis granite massif (Eastern Pyrenees, France)

Abstract

Zircon U-Pb 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. 40 Ar/ 39 Ar 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.

Anisotropy of magnetic susceptibility of the Pyrenean granites

“…The U-Pb ages published in recent decades for the Pyrenean granites indicate that the Variscan plutonism of the Pyrenees is essentially Upper Carboniferous at 301-314 Ma (Denèle, Paquette, Olivier, & Barbey, 2011) and syntectonic (Gleizes, Crevon, Asrat, & Barbey, 2006;Guerrot, 1998Guerrot, , 2001Maurel, Respaut, Monié, Arnaud, & Brunel, 2004;Olivier, Gleizes, & Paquette, 2004;Paquette, Gleizes, Leblanc, & Bouchez, 1997;Roberts, Pin, Clemens, & Paquette, 2000;Romer & Soler, 1995). A younger plutonism, Permian in age (267 ± 1 Ma) has recently been obtained for the Aya pluton (Denèle et al, 2011).…”

Structure, age and mode of emplacement of the Hercynian Bordères-Louron pluton (Central Pyrenees, France)

“…Zircon U-Pb dating on east Pyrenean plutons shows that they emplaced during the Upper Carboniferous. Available ages are westwards: 307 -1 Ma for Saint Arnac (Olivier et al 2004), 307 -3 Ma for Qué rigut (Roberts et al 2000), 305 -3 Ma for Mont-Louis-Andorra (Romer and Soler 1995;Maurel et al 2004) and 312 -3 Ma for Bassiè s (Paquette et al 1997). The slightly older age of the Bassiè s pluton raises the question of the emplacement ages of plutons in the central and western Pyrenees where U-Pb geochronological data are poorly constrained with two ages in the eastern part of the Cauterets pluton at 301 -7 Ma (Guerrot 1998) and in the Eaux-Chaudes pluton at 301 -9 Ma (Guerrot 2001).…”

Detrital zircons from the Ordovician rocks of the Pyrenees: Geochronological constraints and provenance

“…Syn-to late-orogenic granitoids (late Bashkirian-Kasimovian, Romer and Soler, 1995;Maurel et al, 2004;Aguilar et al, 2014 and references therein) intruded mainly into the upper levels of the succession. It should be noted that in the Pyrenees no tectono-metamorphic events related to the Cadomian orogeny have ever been described and that only a weakly developed Ordovician deformation (Mid?…”