Biolithogenesis of Microcodium: Elucidation
- V. Paul Wright3 and
- Maurice E. Tucker4
Published Online: 8 APR 2009
Copyright © 1991 The International Association of Sedimentologists
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
Postgraduate Research Institute of Sedimentology (PRIS), University of Reading, UK
Department of Geological Sciences, University of Durham, UK
- Published Online: 8 APR 2009
- Published Print: 13 JUN 1991
Print ISBN: 9780632031870
Online ISBN: 9781444304497
- 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
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.