Soil-like Patterns Inside the Rocks: Structure, Genesis, and Research Techniques

Microprofiles established due to the activity of endolithic communities inside the solid rocks of East Antarctica were studied with the approaches of soil science. Major products of endolithic rock transformation in situ are the silty-sandy fine earth and abundant organo-mineral films that are formed within the porous space of endolithic system. Such films are the result of interaction between biofilms and mineral surfaces and reflect elemental composition of both components, mainly comprising C, O, Si, Al, Fe, K, Ca, Na, and Mg. Morphology observed on different hierarchical levels and microtomography data indicated that different layers of endolithic system are connected with the fracture network serving for the elements transfer in the subsurface part of solid rocks. Examined profiles in granites with high quartz content had clear eluvial-illuvial differentiation patterns similar to macro-profile of a common Podzol (Spodsol) on loose substrates. It is shown, that subaerial segment of hard rocks is not sealed and is potentially permeable for dissolved products of endolithic weathering and pedogenesis. As a unique result-the soil-like pattern is established inside the massive, crystalline rock. Understanding modern processes in endolithic systems is of fundamental importance to decrypt paleosol record, as such systems may be the closest modern analogues of protosoils that existed on our planet before the higher vascular plants with root systems established.