Limits on Late Ordovician Eustatic Sea-Level Change from Carbonate Shelf Sequences: An Example from Anticosti Island, Quebec

  1. Henry W. Posamentier2,
  2. Colin P. Summerhayes3,
  3. Bilal U. Haq4 and
  4. George P. Allen5
  1. D. G. F. Long

Published Online: 15 APR 2009

DOI: 10.1002/9781444304015.ch24

Sequence Stratigraphy and Facies Associations

Sequence Stratigraphy and Facies Associations

How to Cite

Long, D. G. F. (1993) Limits on Late Ordovician Eustatic Sea-Level Change from Carbonate Shelf Sequences: An Example from Anticosti Island, Quebec, in Sequence Stratigraphy and Facies Associations (eds H. W. Posamentier, C. P. Summerhayes, B. U. Haq and G. P. Allen), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304015.ch24

Editor Information

  1. 2

    Plano, Texas, USA

  2. 3

    Godalming, UK

  3. 4

    Washington, DC, USA

  4. 5

    St Remy les Chevreuses, France

Author Information

  1. Department of Geology, Laurentian University, Sudbury, Ontario, Canada P3E 2C6

Publication History

  1. Published Online: 15 APR 2009
  2. Published Print: 17 NOV 1993

ISBN Information

Print ISBN: 9780632035489

Online ISBN: 9781444304015

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Keywords:

  • limits on late Ordovician eustatic sea-level change from carbonate shelf sequences from Anticosti Island, Quebec;
  • Anticosti Island - tectonic framework and subsidence history;
  • Vaureal Formation and Ellis Bay Formation of Anticosti Island;
  • Hummocky cross-stratification in sandy facies, Velleda Member;
  • conglomeratic facies in Laframboise Member;
  • abundant corals and algal oncolites in Laframboise Member – accumulation in water depths of less than 10 m;
  • blackened top of inter-reef strata

Summary

Short-term fluctuations in global sea level during late Ordovician and early Silurian times are thought to be directly related to volume changes within a continental ice sheet, centred on the Gondwana super-continent. The extent and frequency of eustatic sea-level change are best recorded in shallow-marine strata deposited far from the loading effects of the ice sheet, where the marine record is sufficiently long to permit calculation of tectonic subsidence rates.

The St Lawrence Platform of eastern Canada contains a thick, continuous sequence of early Ordovician to early Silurian marine carbonates, with minor mudstones and quartz-rich sandstones which record the depositional history of a carbonate ramp to platform sequence on the northwestern margin of lapetus ocean. Five transgressive–regressive cycles can be recognized in the late Rawtheyan and Hirnantian strata which form the uppermost Vauréal and Ellis Bay Formations on Anticosti Island. Mean shelf subsidence rates for this part of the St Lawrence Platform fell from a mean of 26 cm/1000 yr in the Ashgill to 4 cm/1000 yr in the Wenlock. Comparison of estimated subsidence rates with the distribution of depth-dependent facies in Hirnantian strata of Anticosti Island indicates a maximum synglacial sea-level change of 32 to 36 m in the latest Ordovician.