Rhizoliths in Terrestrial Carbonates: Classification, Recognition, Genesis and Significance

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

Published Online: 8 APR 2009

DOI: 10.1002/9781444304497.ch6

Calcretes

Calcretes

How to Cite

Klappa, C. F. (1991) Rhizoliths in Terrestrial Carbonates: Classification, Recognition, Genesis and Significance, in Calcretes (eds V. P. Wright and M. E. Tucker), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304497.ch6

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. Gulf Canada Resources Inc., P.O. Box 130, Calgary, Alberta, Canada T2P 2H7, 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:

  • rhizoliths in terrestrial carbonates - classification;
  • rhizoliths, organosedimentary structures resulting in preservation of roots;
  • rhizoliths and associated features of the rhizosphere, indicating terrestrial conditions;
  • plant roots, accelerating weathering of rocks;
  • calcretization, involving modification or obliteration of precursor fabrics;
  • roots, fundamental contributors to pedodia-genetic processes

Summary

Rhizoliths are defined as organosedimentary structures resulting in the preservation of roots of higher plants, or remains thereof, in mineral matter. They are abundant and characteristic features of Quaternary terrestrial carbonates (calcretes and aeolianites) from coastal regions of the western Mediterranean. Field and petrographic observations indicate that five basic types of rhizoliths can be recognized: (1) root moulds, which are tubular voids that outline positions of former, now decayed roots; (2) root casts, which are sediment- and/or cement-filled root moulds; (3) root tubules, which are cemented cylinders around root moulds; (4) rhizocretions s.s., which are pedodiagenetic mineral accumulations (here low magnesian calcite) around living or dead plant roots; and (5) root petrifactions, which are mineral impregnations or mineral replacements of organic matter whereby anatomical features of roots have been preserved partially or totally. Apart from rhizoliths themselves, roots of higher plants are responsible for the formation of numerous and characteristic features of pedogenetically affected terrestrial carbonates. Plant roots are responsible for, or contribute to, the formation of alveolar textures, in situ brecciation (rhizobrecciation) textures, horizontal sheet cracks, vertically elongate glaebules (concretionary soil structures) and micritization (rhizo-micritization) within terrestrial carbonates. Rhizoliths, together with the above features, are products of pedodiagenesis. More significantly, rhizoliths and related features are indicators of palaeosols and hence of subaerial vadose environments in ancient (post-Silurian) successions.