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Biologically mediated weathering in modern cryptogamic ground covers and the early Paleozoic fossil record

Ria Mitchell Orcid Logo, Christine Strullu-Derrien, Paul Kenrick

Journal of the Geological Society, Volume: 176, Issue: 3, Pages: 430 - 439

Swansea University Author: Ria Mitchell Orcid Logo

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DOI (Published version): 10.1144/jgs2018-191

Abstract

Specific micro-weathering features and biochemically derived residues formed by living organisms can be used asbiomarkers to infer the presence of biological communities within sedimentary units of ancient ecosystems. We examinedbasaltic soil minerals from modern cryptogamic ground covers (CGCs) in...

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Published in: Journal of the Geological Society
ISSN: 0016-7649 2041-479X
Published: 2019
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URI: https://cronfa.swan.ac.uk/Record/cronfa51050
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Abstract: Specific micro-weathering features and biochemically derived residues formed by living organisms can be used asbiomarkers to infer the presence of biological communities within sedimentary units of ancient ecosystems. We examinedbasaltic soil minerals from modern cryptogamic ground covers (CGCs) in Iceland and compared these with two early Paleozoicfossil systems. Nine biologically mediated weathering features (BWFs) were identified in modern soils including micron-scalesurface trenching and penetrative tunnels, which are attributed to the actions of bacteria, fungi and exudates. Specific BWFs areassociated with Fe residues, and with Fe-rich bio-precipitated nodules. Further, putative comparable features and Fe enrichmentare identified in palaeosols from the late Silurian (Llansteffan, south Wales) and the Early Devonian (Rhynie chert, Scotland).Although we are cautious about attributing biological affinity to individual isolated features, our results demonstrate thepotential of using multiple BWF types as a collective together with their chemical signatures as new proxies to understandcommunity structure and interactions in early terrestrial ecosystems. This new information is the first evidence of interactionsbetween ancient CGC-like organisms and substrate or soil inorganic components in the fossil record, and demonstrates theability of CGC-like biospheres to contribute to mineral weathering, soil development and biogeochemical cycling duringthe early Paleozoic.
Keywords: Weathering; evolution; soil development; microbe interactions
College: Faculty of Science and Engineering
Issue: 3
Start Page: 430
End Page: 439