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

Mitchell, Ria L.; Strullu‐Derrien, Christine; Kenrick, Paul

doi:10.1144/jgs2018-191

Cited by 18 publications

(31 citation statements)

References 67 publications

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“…This difference might be a factor of time, where hole type 2 morphologies are created first and a longer duration of weathering leads to the creation of larger, more rounded and branched tunnels (hole type 1). Hole type 1 has rounded sides and circular cross section compared with type 2; these are reminiscent of 2D tunnel structure observed in other studies 18,25 which are reported as being from a biological origin, usually fungal 48 . Fungal tunnels within soil minerals have been explained as a result of dissolution and 'boring' by combined biomechanical forcing and biochemical alteration; the tunnel retains its shape following the death and degradation of the hyphae 24,44,45 .…”

Section: Discussionsupporting

confidence: 56%

“…Our findings demonstrate that an assortment of markings are present on the surface of a soil grain of interest. These are reminiscent of the surficial bowls, tramlines, elongate troughs, and internal pore networks previously described as biologically mediated weathering features (BWFs) by 18 that are common in modern CGC soils. Although no microorganisms were observed colonising the grain surface from our XRM scans (the voxel size is not small enough to resolve them; Supplementary Methods S10), the presence of these features could suggest a biological origin.…”

Section: Discussionmentioning

confidence: 93%

“…Previous research on modern CGCs developing on primordial land surfaces from Iceland were mostly limited to 2D investigations, mainly of grain surface processes 18 . These revealed biologicallymediated weathering features (BWFs) on volcanic glass and scoria within soils that were attributed to the actions of different organisms (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…symbiosis, root-mediated dissolution) 18 . Prominent among these were 'tunnels', which are thought to be created by 'boring' fungal hyphae [18][19][20][21][22][23][24][25][26][27][28][29] . Here, we develop a novel correlative microscopy workflow across modes, dimensions and scales to investigate the physical, chemical and morphological characteristics of these tunnels.…”

Section: Introductionmentioning

confidence: 99%

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Correlative Microscopy: a tool for understanding soil weathering in modern analogues of early terrestrial biospheres

Mitchell¹,

Davies²,

Kenrick³

et al. 2021

Preprint

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Correlative imaging provides a method of investigating complex systems by combining analytical (chemistry) and imaging (tomography) information across dimensions (2D-3D) and scales (centimetres-nanometres). We studied weathering processes in a modern cryptogamic ground cover (CGC) from Iceland, containing early colonizing, and evolutionary ancient, communities of mosses, lichens, fungi, and bacteria. Targeted multi-scale X-ray Microscopy (XRM) of a grain in-situ within a soil core revealed networks of surficial and internal features (tunnels) originating from organic-rich surface holes. Further targeted 2D grain characterisation by optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (SEM-EDS), following an intermediate manual correlative preparation step, revealed Fe-rich nodules within the tunnels. Finally, nanotomographic imaging by focussed ion beam microscopy (FIB-SEM) revealed coccoid and filamentous-like structures within subsurface tunnels, as well as accumulations of Fe and S in grain surface crusts, which may represent a biological rock varnish/glaze. We attribute these features to biological processes. This work highlights the advantages and novelty of the correlative imaging approach, across scales, dimensions, and modes, to investigate biological weathering processes. Further, we demonstrate correlative microscopy as a means of identifying fingerprints of biological communities, which could be used in the geologic rock record and on extra-terrestrial bodies.

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Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Correlative Microscopy: a tool for understanding soil weathering in modern analogues of early terrestrial biospheres

Mitchell¹,

Davies²,

Kenrick³

et al. 2021

Preprint

Self Cite

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“…Early development of terrestrial ecosystems often includes interactions between cryptogamic lithobiontic communities (cyanobacteria, green algae, lichens, and fungi together with other heterotrophic organisms), the lithomatrix of rocks and the given climatic conditions ( Mergelov et al., 2018 ; Mitchell et al., 2019 ). Since the occurrence of life on Earth, the interplay between the biotic and abiotic world is amongst the most ancient processes shaping the earth's surface.…”

Section: Introductionmentioning

confidence: 99%

Lichens Bite the Dust – A Bioweathering Scenario in the Atacama Desert

et al. 2020

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Summary Bioweathering mediated by microorganisms plays a significant role in biogeochemical cycles on global scales over geological timescales. Single processes induced by specific taxa have been described but could rarely be demonstrated for complex communities that dominate whole landscapes. The recently discovered grit crust of the coastal Atacama Desert, which is a transitional community between a cryptogamic ground cover and a rock-bound lithic assemblage, offers the unique chance to elucidate various bioweathering processes that occur simultaneously. Here, we present a bioweathering scenario of this biocenosis including processes such as penetration of the lithomatrix, microbial responses to wet-dry cycles, alkalinolysis, enzyme activity, and mineral re-localization. Frequently occurring fog, for example, led to a volume increase of microorganisms and the lithomatrix. This, together with pH shifts and dust accumulation, consequently results in biophysical breakdown and the formation of a terrestrial protopedon , an initial stage of pedogenesis fueled by the grit crust .

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Evolutionary synchrony of Earth’s biosphere and sedimentary-stratigraphic record

Davies

Shillito

Slater

et al. 2020

Earth-Science Reviews

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The landscapes and seascapes of Earth's surface provide the theatre for life, but to what 12 extent did the actors build the stage? The role of life in the long-term shaping of the 13 planetary surface needs to be understood to ascertain whether Earth is singular among known 14 rocky planets, and to frame predictions of future changes to the biosphere. Modern 15 geomorphic observations and modelling have made strides in this respect, but an under-16 utilized lens through which to interrogate these questions resides in the most complete 17 tangible record of our planetary history: the sedimentary-stratigraphic record (SSR). The 18 characteristics of the SSR have been frequently explained with reference to changes in 19 boundary conditions such as relative sea level, climate, and tectonics. Yet despite the fact that 20 the long-term accrual of the SSR was contemporaneous with the evolution of almost all 21 domains of life on Earth, causal explanations related to biological activity have often been 22 overlooked, particularly within siliciclastic strata. This paper explores evidence for the ways 23 in which organisms have influenced the SSR throughout Earth history and emphasizes that 24 further investigation can help lead us towards a mechanistic understanding of how the 2 25 planetary surface has co-evolved with life. The practicality of discerning life signatures in 26 the SSR is discussed by: 1) distinguishing biologically-dependent versus biologically-27 influenced sedimentary signatures; 2) emphasizing the importance of determining relative 28 time-length scales of processes and demonstrating how different focal lengths of observation 29 (individual geological outcrops and the complete SSR) can reveal different insights; and 3) 30 promoting an awareness of issues of equifinality and underdetermination that may hinder the 31 recognition of life signatures. Multiple instances of life signatures and their historic range 32 within the SSR are reviewed, with examples covering siliciclastic, biogenic and chemogenic 33 strata, and trigger organisms from across the spectrum of Earth's extant and ancient life. 34 With this novel perspective, the SSR is recognised as a dynamic archive that expands and 35 complements the fossil and geochemical records that it hosts, rather than simply being a 36 passive repository for them. The SSR is shown to be both the record and the result of long-37 term evolutionary synchrony between life and planetary surface processes. 38 42 precipitation from solution. Where it is tractable, in exposed outcrop, cores or seismic 43 sections, the SSR has immense value as a record of ancient surface processes. It is the 44 primary repository of deep time geochemical and fossil evidence, and the only tangible 45

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

Cited by 18 publications

References 67 publications

Correlative Microscopy: a tool for understanding soil weathering in modern analogues of early terrestrial biospheres

Correlative Microscopy: a tool for understanding soil weathering in modern analogues of early terrestrial biospheres

Lichens Bite the Dust – A Bioweathering Scenario in the Atacama Desert

Evolutionary synchrony of Earth’s biosphere and sedimentary-stratigraphic record

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