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GEOREF RECORD

Taconian melanges in the parautochthonous zone of the Quebec Appalachians revisited; implications for foreland basin and thrust belt evolution

F. A. Comeau, Donna Kirkwood, M. Malo, E. Asselin and R. Bertrand
Taconian melanges in the parautochthonous zone of the Quebec Appalachians revisited; implications for foreland basin and thrust belt evolution
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (December 2004) 41 (12): 1473-1490

Abstract

In the Quebec Appalachians, disruption, imbrication, and thrusting of the Taconian foreland basin sequence are responsible for the development of chaotic units within the turbiditic sequence of the Caradocian Sainte-Rosalie Group, the main lithologic assemblage of the parautochthonous zone. These chaotic units have been termed olistostromes or tectonosomes on the basis of field criteria and following Pini's (1999) classification. Olistostromal units containing blocks of the middle mudstone (Utica Shale) and upper turbidite units (Ste-Rosalie Group) of the foreland basin and spanning the Caradocian N. gracilis, C. americanus, O. ruedemanni, and C. spiniferus graptolite zones were deposited and incorporated into the Sainte-Rosalie Group. Disruption of more competent beds of the flyschic sequence and fault stacking and slicing of older rock units occurred along major thrust faults and now form structurally aligned corridors or tectonosomes. Graptolites and new chitinozoan data from both olistostromes and tectonosomes indicate older ages (early Late Ordovician) than the flysch units of Sainte-Rosalie Group (mid Late Ordvician). Lithological, stratigraphic, and structural criteria indicate that tectonosome slices are imbricated foreland basin rocks that are correlative to the Black River, Trenton, Utica, Sainte-Rosalie, and Lorraine groups of the Laurentian platform. Thermal maturation data indicates that disruption of the autochthonous sequence, and folding and thrusting of the entire foreland basin sequence, must have occurred shortly after their deposition. Contrary to what had been suggested, blocks in the olistostromes and tectonosomes were not derived from the allochthonous Chaudiere thrust sheet, even though it presently marks the southern contact with the parautochthonous zone. Imbrication of the foreland basin sequence must have occurred before emplacement of the Chaudiere thrust sheet.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 41
Serial Issue: 12
Title: Taconian melanges in the parautochthonous zone of the Quebec Appalachians revisited; implications for foreland basin and thrust belt evolution
Affiliation: Universite Laval, Departement de Geologie et de Genie Geologique, Sainte-Foy, QC, Canada
Pages: 1473-1490
Published: 200412
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 61
Accession Number: 2005-040922
Categories: StratigraphyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Geol. Surv. Can., Contrib. No. 2003105
Illustration Description: illus. incl. sects., strat. col., geol. sketch maps
N45°00'00" - N47°00'00", W74°00'00" - W71°00'00"
Secondary Affiliation: INRS-Eau, CAN, CanadaRessources Naturelles du Canada, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200515
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