Pervasive Dolomitization of a Subtidal Carbonate Ramp, Silurian and Devonian, Illinois Basin, USA

  1. Bruce Purser,
  2. Maurice Tucker and
  3. Donald Zenger
  1. J. M. Kruger and
  2. J. A. Simo

Published Online: 14 APR 2009

DOI: 10.1002/9781444304077.ch22

Dolomites: A Volume in Honour of Dolomieu

Dolomites: A Volume in Honour of Dolomieu

How to Cite

Kruger, J. M. and Simo, J. A. (1994) Pervasive Dolomitization of a Subtidal Carbonate Ramp, Silurian and Devonian, Illinois Basin, USA, in Dolomites: A Volume in Honour of Dolomieu (eds B. Purser, M. Tucker and D. Zenger), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304077.ch22

Author Information

  1. Department of Geology and Geophysics, University of Wisconsin-Madison, 1215 West Dayton Street, Madison, Wisconsin 53706, USA

  1. 1560 Lila Ave., Baton Rouge, Louisiana 70820, USA

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 25 MAY 1994

ISBN Information

Print ISBN: 9780632037872

Online ISBN: 9781444304077

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Keywords:

  • pervasive dolomitization of subtidal carbonate ramp, Silurian and Devonian, Illinois Basin, USA;
  • pre-Kaskaskia sequence-bounding unconformity - cuts downsection through Tippecanoe II to the north;
  • dolomite stratigraphy, petrography and timing;
  • dolomite fabrics in Middle Devonian rocks overlying pre-Kaskaskia unconformity;
  • dolomite geochemistry;
  • dolomite in Silurian and Devonian rocks - not from single dolomitization event

Summary

Silurian and Devonian rocks of the Tippecanoe II and Kaskaskia I sequences in the Illinois Basin provide an example of extensively dolomitized subtidal carbonate rocks. Dolomite in predominantly midramp, fine-grained Silurian and Devonian rocks occurs as two types: a pervasive and extensive massive grey dolomite that cross-cuts facies and depositional sequences and extends across an interregional unconformity, and a less abundant brown type that occurs in tabular bodies that cross-cut bedding. Stratigraphic and petrographic data indicate that both brown and grey dolomite range in age from Silurian to Devonian. Brown and grey dolomites have similar δ18O and δ13C values and overlapping major, minor and trace element concentrations. The similar or overlapping chemical signatures suggest that all dolomites precipitated from similar or related fluids. Oxygen and strontium isotopic values indicate that contemporaneous Silurian and Devonian seawater or modified seawater was the dolomitizing fluid, and that dolomitization was a continuous, or quasicontinuous, process. Seawater was probably pumped through Silurian and Devonian sediments during rises and falls in relative sea level.