Biolithogenesis of Microcodium: Elucidation

  1. V. Paul Wright3 and
  2. Maurice E. Tucker4
  1. Colin F. Klappa

Published Online: 8 APR 2009

DOI: 10.1002/9781444304497.ch5

Calcretes

Calcretes

How to Cite

Klappa, C. F. (1991) Biolithogenesis of Microcodium: Elucidation, in Calcretes (eds V. P. Wright and M. E. Tucker), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304497.ch5

Editor Information

  1. 3

    Postgraduate Research Institute of Sedimentology (PRIS), University of Reading, UK

  2. 4

    Department of Geological Sciences, University of Durham, UK

Author Information

  1. Jane Herdman Laboratories of Geology, University of Liverpool, Liverpool, UK

  1. Memorial University of Newfoundland, Department of Geology, St John's, Newfoundland, Canada A1B 3X7, Canada

Publication History

  1. Published Online: 8 APR 2009
  2. Published Print: 13 JUN 1991

ISBN Information

Print ISBN: 9780632031870

Online ISBN: 9781444304497

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Keywords:

  • biolithogenesis of microcodium - elucidation;
  • unusual calcite structures, Microcodium elegans;
  • Microcodium, occurring in Tertiary rocks;
  • Microcodium, grains displaying re-entrants or embayments;
  • vesicular-arbuscular endomycorrhiza;
  • Microcodium, relating to fungus-root association

Summary

Petrographic studies of Tertiary and Pleistocene caliche from the western Mediterranean show some unusual calcite structures. These structures were designated Microcodium elegans Glüuck 1912. New data are presented which question earlier interpretations with regard to the origin of this structure. The new discovery of Microcodium in Recent soils extends its stratigraphic range into the Holocene. Retention of fine detail in Recent samples, revealed by light microscopy and SEM, has suggested an origin hitherto unconsidered, calcification of mycorrhizal associations. Ancient and Recent Microcodium fabrics are compared; sufficient preservation of ultrastructure in the Ancient indicates a homologous origin.

Environmental, stratigraphic and palaeoecological significance of Microcodium is discussed; correct recognition indicates existence of a palaeosol, and hence is a valuable criterion for recognition of continental conditions, cessation of sedimentation, subaerial exposure, and time-equivalent horizons. In particular, Microcodium is a characteristic component of caliche in the western Mediterranean. A review of the literature suggests that its presence may have been overlooked or misinterpreted in other parts of the world and, thus, may be more widespread than hitherto suspected.

This study, in its embryonic stage of development, illumines the potential importance of biolithogenesis within terrestial carbonates.