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Determining which geological target patterns are Liesegang

Ascertain whether all geological target patterns observed in rocks are formed by Liesegang precipitation, and develop definitive criteria to distinguish Liesegang-generated targets from those produced by other physical–chemical mechanisms.

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Background

Rocks frequently display concentric banding or rings termed "target patterns" that geologists often refer to as Liesegang rings by analogy with laboratory precipitation systems. However, multiple self-organization mechanisms can produce similar morphologies in soft matter and geological contexts.

The review explicitly states uncertainty about the universality of the Liesegang mechanism in geological target patterns and underscores the need to reserve the term "Liesegang rings" for cases demonstrably produced by that mechanism.

References

Some geological target patterns may indeed be formed by a Liesegang mechanism (see the discussion regarding agates, Sec.~\ref{sec:agates}), but it is not clear that all of them are, and, as we discuss below, there is a variety of physical-chemical mechanisms that can produce target patterns in soft matter.

— Self-Organized Pattern Formation in Geological Soft Matter (2412.18999 - Cartwright et al., 25 Dec 2024) in Subsection Target patterns