272-5 Exploring the Synergistic Influence of Curvature and Thermal Cycles on Granite Dome Fractures

Session: Faults, Fractures, and Geomechanics for the Energy Transition (Posters)

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Abstract:

The processes that drive exfoliation and its associated cracking on granite domes remain poorly understood, thus limiting our knowledge of landscape evolution and the sensitivity of these and similar processes to climatic variation in granite terrains. Cyclic thermal forcing has been proposed as a primary driver of exfoliation, however the magnitudes of resultant tensile stresses are difficult to quantify as they depend on superimposed temperature cycles - that vary hourly, daily, and seasonally with weather - and the multi-scale curvature of bedrock surfaces (Martel, 2011). In this study we use a formal surface theory approach applied to spectrally filtered digital elevation models to calculate topographic curvature spectra for several domes in the Appalachian and Sierra Nevada mountains. These curvatures are then used as inputs to calculate surface normal tensile stress arising from thermal cycling - the inputs for which are derived from both synthetic and field measured temperature data. We use these calculations to identify both topographic and thermal depth domains of likely fracturing based on where their synergy results in stress maxima. Finally, we compare predicted depths of stress concentrations with field data of the thicknesses of exfoliated sheets measured in several field sites. Our results indicate that most exfoliation sheets in our field areas can be plausibly linked to strain from cyclic thermal forcing of a curved surface.

This approach offers new insights into where and why exfoliation joints may initiate with implications for predicting rockfall risk and better understanding the long-term evolution of granitic landscapes.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7566

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