| Titre | Timing of tectonometamorphism across the Green Mountain anticlinorium, northern Vermont Appalachians: 40Ar/39Ar data and correlations with southern Quebec |
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| Auteur | Castonguay, S ;
Kim, J; Thompson, P J; Gale, M H; Joyce, N; Laird, J; Doolan, B
L |
| Source | Geological Society of America Bulletin vol. 124, no. 3-4, 2012 p. 352-367, https://doi.org/10.1130/B30487.1 |
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| Année | 2012 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20100416 |
| Éditeur | Geological Society of America |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/B30487.1 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Québec |
| SNRC | 21E; 21L; 31H; 31I/01; 31I/02; 31I/07; 31I/08; 31I/09 |
| Région | Vermont; Appalachians |
| Lat/Long OENS | -73.3333 -70.5000 47.0000 42.7333 |
| Sujets | milieux tectoniques; cadre tectonique; interprétations tectoniques; métamorphisme; datation argon-argon; datations argon-argon; datations radiométriques; Anticlinorium de Green Mountain ; géochronologie;
tectonique; géologie structurale; Mésozoïque |
| Illustrations | cartes de localisation; photomicrographies; coupes transversales; graphiques |
| Programme | GEM : La géocartographie de l'énergie et des minéraux Bassins sédimentaires d'Hudson / Foxe Bay |
| Diffusé | 2011 11 21 |
| Résumé | (disponible en anglais seulement)
In the pre-Silurian lithotectonic units of the northern Vermont Appalachians, the timing of orogenesis and tectonometamorphism has traditionally been ascribed
to the combined effects of the Middle Ordovician Taconian orogeny and Middle to Late Devonian Acadian orogeny. However, numerous geo chronological studies throughout the Northern Appalachians, including neighboring southern Quebec, have obtained
Silurian and Early Devonian age data that document more or less continuous tectonometamorphic activity throughout the Ordovician - Devonian. The structural and metamorphic evolution of northern Vermont can be separated into three regional phases,
which are characterized by distinct structures, fabrics, and metamorphic parageneses. The fi rst phase (D1), associated with westward emplacement of various thrust slices leading to crustal thickening and regional metamorphism, and the second phase
(D2), characterized by bivergent structures and metamorphic overprint, have both been considered to be Taconian. The third phase, the structure and fabric
of which are also observed in the Silurian - Devonian rocks to the east, is considered to be
Acadian. We present new step-heating and spot fusion 40Ar/39Ar geochronological data on amphibole and fabric-forming muscovite from samples taken across the Green Mountain anticlinorium, which, coupled with published data, provide improved age
constraints on tectonometamorphism of D1 (latest Cambrian to Middle Ordovician), D2 (Silurian - Early Devonian), and D3 (Middle Devonian) events. By comparing structural and metamorphic characteristics, and now timing, these phases are interpreted to
be correlative to the tripartite tectonometamorphic evolution documented in southern Quebec, and they further exemplify the along-strike diachronism of tectonism induced by the inherited irregular geometry of the Laurentian margin. |
| GEOSCAN ID | 287844 |
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