Reassessment of the Microbial Role in Mn-Fe Nodule Genesis in Andean Paleosols

W. C. Mahaney*, D. H. Krinsley, C. C. R. Allen, J. Ditto, K. Langworthy, A. D. Batchelor, M. Lecompte, M. W. Milner, K. M. Hart, S. S. O'Reilly, B. P. Kelleher, R. G. V. Hancock

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Citations (Scopus)


The presence of Mn-Fe nodules in the epipedons (surface horizons) of paleosols of presumed Upper Neogene age in the northwestern Venezuelan Andes have been interpreted as products of inorganic oxidation and reduction processes operating over the full range of glacial and interglacial cycles that affected paleosol morphogenesis. New microscopic/chemical data from combined SEM-EDS-FIB analyses of representative Mn-Fe nodules indicate microbes play an important role in Mn/Fe precipitation leading to their genesis in alpine Mollisols (Argiustolls). Although the prevailing new data are based mainly on fossil forms of filamentous bacteria and fungi and other biogenic pseudomorphs that may represent the former resident bacteria, the presence of extant microbes must await field experiments/collection, followed by a molecular microbiology approach to determine the biological drivers of metal precipitation. As in other terrestrial niche environments, microbes are seen here to play a role, perhaps a key one, in the morphogenesis of paleosols of importance in upper Neogene paleoenvironmental reconstruction.

Original languageEnglish
Pages (from-to)27-41
Number of pages15
JournalGeomicrobiology Journal
Issue number1
Early online date25 Jun 2014
Publication statusPublished - 2015


  • Andean paleosols
  • microbial assisted soil nodule growth
  • Mn nodules
  • redox role in nodule genesis reassessed

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Microbiology
  • Environmental Science(all)
  • Environmental Chemistry

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    Mahaney, W. C., Krinsley, D. H., Allen, C. C. R., Ditto, J., Langworthy, K., Batchelor, A. D., Lecompte, M., Milner, M. W., Hart, K. M., O'Reilly, S. S., Kelleher, B. P., & Hancock, R. G. V. (2015). Reassessment of the Microbial Role in Mn-Fe Nodule Genesis in Andean Paleosols. Geomicrobiology Journal, 32(1), 27-41.