Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schroetter, J.-M. Articles by Villeneuve, M. E. Search for Related Content GeoRef GeoRef Citation

Syncollisional basin development in the Appalachian orogen—The Saint-Daniel Mélange, southern Québec, Canada

Jean-Michel Schroetter^,1, Alain Tremblay^,2, Jean H. Bédard^,3 and Mike E. Villeneuve^#,4

¹ Institut National de la Recherche Scientifique—Eau, Terre et Environnement, 490 de la Couronne, Québec, PQ G1K 9A9, Canada
² Département des Sciences de la Terre, Université du Québec à Montréal, CP 8888, Succursale centre ville, Montréal, PQ H3C 3P8, Canada
³ Geological Survey of Canada—Québec, 490 de la Couronne, Québec, PQ G1K 9A9, Canada
⁴ Geological Survey of Canada—Ottawa, 601 Booth St., Ottawa, Ontario K1A OE8, Canada

The Saint-Daniel Mélange is an orogen-scale sedimentary basin of the Québec Appalachians that is commonly interpreted as the remnant of a subduction complex formed during the Taconian orogeny. However, geochronological, structural, and stratigraphical data from Laurentian continental margin rocks and adjacent ophiolitic rocks in southern Québec indicate that the Saint-Daniel Mélange is an olistostromal, syncollisional piggyback basin that represents the base of the Magog Group forearc basin. The regional stratigraphic framework of the Saint-Daniel Mélange and its relationships with underlying and overlying rock units have been established on the basis of six stratigraphic sections from the Thetford-Mines, Asbestos, and Mont-Orford ophiolitic complexes. Our results imply that (1) the Saint-Daniel Mélange is a sedimentary sequence that unconformably overlies different structural and pseudostratigraphic levels of the southern Québec ophiolites; (2) it is made up of four distinct and laterally discontinuous units that record the obduction of ophiolites onto Laurentia and exhumation of basement rocks, followed by subsidence and deposition of the overlying Saint-Victor Formation of the Magog Group; (3) the sedimentary rocks of the Saint-Daniel record a transition from ophiolite-dominated to continental sources, indicating progressive exhumation of both the ophiolite and the continental margin upon which it was obducted; ⁴⁰Ar/³⁹Ar analysis of muscovite from metamorphic rock fragments in debris flows of the mélange yield an age of 467 ± 2 Ma, which is within the range of Ar ages measured in metamorphic rocks that underlie the ophiolites, and indicates the uplift of metamorphosed continental deposits during or shortly after obduction; (4) the Saint-Daniel Mélange is stratigraphically overlain by the Magog Group and represents the base of a syncollisional basin developed in a forearc setting during the Taconian orogeny.

Key Words: Appalachians • Québec • ophiolite • syncollisional basin • mélange

This article has been cited by other articles:

				S. Castonguay, G. Ruffet, and A. Tremblay Dating polyphase deformation across low-grade metamorphic belts: An example based on 40Ar/39Ar muscovite age constraints from the southern Quebec Appalachians, Canada Geological Society of America Bulletin, July 1, 2007; 119(7-8): 978 - 992. [Abstract] [Full Text] [PDF]

				J. F. Tull, C. I. Barineau, P. A. Mueller, and J. L. Wooden Volcanic arc emplacement onto the southernmost Appalachian Laurentian shelf: Characteristics and constraints Geological Society of America Bulletin, March 1, 2007; 119(3-4): 261 - 274. [Abstract] [Full Text] [PDF]