Progressive Filling of a Confined Middle Ordovician Foreland Basin Associated with the Taconic Orogeny, Quebec, Canada

  1. P. A. Allen and
  2. P. Homewood
  1. R. N. Hiscott1,
  2. K. T. Pickering2 and
  3. D. R. Beeden3

Published Online: 5 MAY 2009

DOI: 10.1002/9781444303810.ch17

Foreland Basins

Foreland Basins

How to Cite

Hiscott, R. N., Pickering, K. T. and Beeden, D. R. (1986) Progressive Filling of a Confined Middle Ordovician Foreland Basin Associated with the Taconic Orogeny, Quebec, Canada, in Foreland Basins (eds P. A. Allen and P. Homewood), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303810.ch17

Author Information

  1. 1

    Centre for Earth Resources Research, Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland A1B 3X5, Canada

  2. 2

    Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, UK

  3. 3

    Reservoir Geology Division, Poroperm-Geochem Limited, Chester Street, Saltney, Chester CH4 8RD, UK

Publication History

  1. Published Online: 5 MAY 2009
  2. Published Print: 22 DEC 1986

ISBN Information

Print ISBN: 9780632017324

Online ISBN: 9781444303810



  • Palaeozoic of North America;
  • progressive filling of confined Middle Ordovician foreland basin associated with Taconic Orogeny, Quebec, Canada;
  • Ordovician Taconic Orogeny - collision of eastern continental margin of North America with volcanic arc;
  • Taconic-age flysch units in Quebec Reentrant - allochthonous Tourelle, Metis, St Modeste and Deslandes formations;
  • facies classes, groups, and selected facies;
  • Arenig-Llanvirn slope basins;
  • Llandeilo-Mid-Caradoc Basin plain;
  • Mont-St-Pierre (MSP) - member of Cloridorme Formation;
  • Post-Caradoc Foreland-Basin evolution


The Ordovician Taconic Orogeny involved collision of the eastern continental margin of North America with a volcanic arc(s) situated above a SE-dipping subduction zone. Loading of the North American plate by thrust sheets of the thickened accretionary prism produced a complex foreland basin, with depositional remnants extending from Alabama to Newfoundland. In eastern Quebec, the oldest flysch deposits associated with the Taconic Orogeny are Arenig sand-rich submarine fans of the allochthonous Tourelle, Métis and St Modeste formations. These fans are characterized by packets of coarse-grained sandstones separated by interchannel or abandonment-facies siltstones and mudstones. The Tourelle Formation and coeval correlatives were deposited on uplifted continental rise deposits of the earlier passive-margin, suggesting deposition in small slope basins on the orogenic side of the foreland basin.

The main Caradoc–Ashgill fill of the foreland basin consists of (a) basin-floor deposits of the 2.3 km thick allochthonous Deslandes Formation, (b) basin-floor, lobe-fringe and sandstone lobe deposits of the 4.0 km thick parautochthonous Cloridorme Formation, and (c), on the craton side of the basin, black shales and silty carbonates of the autochthonous c. 100 m thick Macasty Formation and the c. 1.0 km thick Vauréal Formation. These units rest, or are inferred to rest, on foundered carbonates like those exposed north of Anticosti Island along the north shore of the St Lawrence River. The lower 1.5–2.0 km of the Cloridorme Formation consists of basin floor deposits with megaturbidites up to 10 m thick that resemble beds described from the modern Mediterranean basins and from the Italian Apennines. The upper 2.0 km consists of alternating coarse sandy lobe deposits like those of the Tourelle Formation, and muddy fan-fringe or lobe-fringe facies to about 500 m thick. The thicker mud intervals appear to represent times of elevated sea-level during filling of the foreland basin. Source-area denudation was essentially complete before the central part of the basin ever reached shelf depths, so that no molasse-type deposits overlie the foreland-basin flysch of eastern Quebec.