Abstract
Subaerial endolithic systems of the current extreme environments on Earth provide exclusive insight into emergence and development of soils in the Precambrian when due to various stresses on the surfaces of hard rocks the cryptic niches inside them were much more plausible habitats for organisms than epilithic ones. Using an actualistic approach we demonstrate that transformation of silicate rocks by endolithic organisms is one of the possible pathways for the beginning of soils on Earth. This process led to the formation of soil-like bodies on rocks in situ and contributed to the raise of complexity in subaerial geosystems. Endolithic systems of East Antarctica lack the noise from vascular plants and are among the best available natural models to explore organo-mineral interactions of a very old “phylogenetic age” (cyanobacteria-to-mineral, fungi-to-mineral, lichen-to-mineral). On the basis of our case study from East Antarctica we demonstrate that relatively simple endolithic systems of microbial and/or cryptogamic origin that exist and replicate on Earth over geological time scales employ the principles of organic matter stabilization strikingly similar to those known for modern full-scale soils of various climates.
Highlights
The new knowledge on Proterozoic and Archaean paleosols[1,2,3,4] is continuously arising the understanding of initial stages of soil production from hard rock in a prokaryotic biosphere is scarcely replenished by the new data due to extremely low preservation potential of these early phases
Loose filaments and cell clusters grow in pore spaces between and around the minerals so that even such organisms as lichens are completely embedded in the rock matrix covered by the hard surface crust
The weathering zones of 0.1–1.0 mm size are formed and can be distinguished by μCT due to the well-established grid of microfractures and numerous roundish pores creating a “perforated” microcellular pattern (Fig. 1d). These zones show clear indications for organo-mineral associations, pointing to the fact that this organic carbon (OC) stabilization mechanism highly important in common soils operates in endolithic systems
Summary
The new knowledge on Proterozoic and Archaean paleosols[1,2,3,4] is continuously arising the understanding of initial stages of soil production from hard rock in a prokaryotic biosphere is scarcely replenished by the new data due to extremely low preservation potential of these early phases. We propose that modern subaerial endolithic systems (comprise endolithic organisms, mineral environment they inhabit and in situ altered organo-mineral byproducts18) of East Antarctica provide the closest appropriate proxy to render the soils progenitors in Precambrian when firstly cyanobacteria and much later fungi and lichens started to colonize silicate hard rocks This is most relevant to the cryptoendolithic varieties. Contemporary subaerial endolithic systems from extreme environments that we report in this study have a great potential to provide insights into early principles of organo-mineral interactions and soil production from hard rocks They lack noise originating from vascular plants with root systems and bryophytes, enable to look at biota-to-mineral interactions of organisms with very old phylogenetic ages (cyanobacteria, fungi, lichen) in “pure” and “pristine” conditions. The closest approach was recently applied by Mitchell et al.[24] who investigated soil development under modern cryptogamic ground covers in Iceland but with more advanced organisms involved e.g. bryophytes, relevant to understanding of vegetation and soils “coevolution” mainly in later times starting from Paleozoic
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
