Dating polyphase deformation across low-grade metamorphic belts: An example based on 40Ar/39Ar muscovite age constraints from the southern Quebec Appalachians, Canada

Thermochronology in Orogenic Systems

“…The second is that, as multiple generations of datable minerals are likely to be found in metamorphic rocks, the most successful thermochronologic studies employ microanalytical techniques to ensure that the results are placed in proper petrographic context. Some examples include DeWolf et al (1993), Cocherie et al (1998), Hawkins and Bowring (1999), Schaltegger et al (1999), Vavra et al (1999), Simpson et al (2000), Terry et al (2000), Catlos et al (2001), Di Vincenzo et al (2001, Rubatto (2002), Zeck and Whitehouse (2002), Castonguay et al (2007), Schoene and Bowring (2007), Daniel and Pyle (2010), Macdonald et al (2010), Qiu et al (2010), and Vignaroli et al (2010).…”

New 40Ar/39Ar age constraints on the Late Palaeozoic tectonic evolution of the western Tianshan (Xinjiang, northwestern China), with emphasis on Permian fluid ingress

“…Cheilletz et al (1999) and Alexandrov et al (2002) have pointed out that saddle-shaped age spectra, similar to the one obtained for muscovite XJ679, may result from the presence of different reservoirs in partially recrystallised mica grains with distinct argon compositions that degas over a different energy interval: a primary, unrecrystallised or inherited domain (low and high temperature steps) and a newly formed or recrystallised one (saddle minimum in the intermediate to high temperature steps). As suggested by Castonguay et al (2007), the younger subdomains formed by growth or recrystallisation could characterise the last isotopic record during a protracted (re)crystallisation history. For muscovite XJ679, this prolonged recrystallisation would have lasted at least 3.5 Ma, between ca.…”

K–Ar age constraints on the evolution of polydeformed fold–thrust belts: The case of the Northern Appalachians (southern Quebec)

“…Recent structural (St-Julien, 1995;Lebel and Kirkwood, 1998;Castonguay et al, 2001a) and geochronological studies (Castonguay et al, 2001b(Castonguay et al, , 2007 on metamorphic rocks of the Laurentian continental margin in Quebec (i.e., the internal Humber zone) have indicated a polyphased structural evolution. Extensive 40 Ar/ 39 Ar dating of amphibole and mica grains yielded three groups of Palaeozoic ages: (1) Middle , associated with the main D 1-2 Taconic compressional event and regional metamorphism (Castonguay et al, 2001c;Tremblay and Castonguay, 2002); (2) , associated with D 3 hinterland-directed structures in the Laurentian margin and wedging of the Grenvillian basement, followed by Late Silurian to Early Devonian (ca.…”