PLAYING WITH SAND AND PLAY DOH: USING SIMPLE ANALOG MODELS TO INVESTIGATE TECTONICS ON EARTH AND OTHER PLANETARY BODIES

Simple analog modeling can be used to understand – and tangibly explain – the most complicated tectonic settings in the solar system. An Yin was an ardent practitioner of simple analog modeling, often distilling complex problems into straightforward conceptual or analog models, whether teaching a summer field class, explaining strike-slip fault systems across central Asia, or trying to understand the Tiger Stripe fractures on Saturn’s moon Enceladus. He would use a mixture of common and unusual materials, such as Play Doh, crunchy peanut butter, therapeutic putty, sand, crushed walnut shells, fallen ceiling tiles, and Hi-Chew candies, to illustrate and interpret complex geometries, kinematics, and inferred dynamics. As most know, An Yin was an inspirationally curious and creative scientist, constrained only by his own imagination, and therefore such physical models were an effective way to bracket the physical viability of a hypothesis. When properly scaled, such models also help illuminate the mechanics of the system. Here we review some recent works using analog models to better understand continental tectonics on Earth and other planetary bodies. Sandbox models reveal the linear correlation between brittle-crust thickness and strike-slip fault spacing that scales to the Earth’s continents and the icy deformed shells of planetary satellites. Two-layer brittle-ductile models can be used to better understand continuum modes of deformation that include V-shaped conjugate faults in central Tibet and the ridged plains of Europa. Play Doh models used in (field) teaching can be used to visualize Basin and Range extension, duplex kinematics, out-of-sequence deformation, pluton emplacement, and so much more. The philosophy around these and other simple analog models is to gain an understanding of how real-world materials behave in a variety of mimicked tectonic settings. The visual and hands-on nature of even the simplest analog experiments serves as a complement to more sophisticated numerical or analog models, especially in unintuitive environments. We can all learn something from An Yin’s creative scientific approach that incorporated foundational field observations, rigorous mechcanical analysis, and sometimes just playing with some sand or Play Doh.