- 1Department of Earth and Climate Science, Indian Institute of Science Education and Research, Pune, India
- 2GFZ Helmholtz Centre for Geosciences, Potsdam, Germany
- 3Institute of Applied Geosciences, Technical University Berlin, Germany
The mean stress state of the continental lithosphere is thought to align with the stresses generated by gravitational potential energy at mid-oceanic ridges. This equilibrium is manifested in an average continental crust of thickness ~40 km and elevations of a few hundred meters as suggested by Airy type compensation and geoid height data 1–3. Our recent data-driven thermomechanical model of the Alpine-Himalayan collision zone (AHCZ) suggested that this balance has a fundamental thermodynamical meaning in that such a state of continental lithosphere maintains a critical crustal thickness with optimal strength controlled by the radiogenic heat production 4. Such a state of critical crustal thickness is referred to as a “stable fixed-point attractor” 4, serving as a “reference tectonic state” 1 for the continental lithosphere. It facilitates comprehending intraplate continental deformation as a finite-amplitude perturbation, where thicker/thinner regions exhibit extension/compression at length scales devoid of flexural effects. We also demonstrated that the high amplitude orogen-type perturbations (e.g., Tibet, Alps) can evolve back to this reference tectonic state via damped oscillatory behaviour consistent with the Wilson Cycle timescale over a few hundred million years. In this study, we expand the data-driven thermomechanical models to a global scale to capture existing variability, particularly in the relatively less evolved orogen of Andes than the AHCZ. Observations of critical crustal thickness persist globally; however, the degree of weakening above the critical crustal thickness is less pronounced in the Andes than in Tibet.
References:
- Coblentz, D. D., Richardson, R. M. & Sandiford, M. On the gravitational potential of the Earth’s lithosphere. Tectonics 13, 929–945 (1994).
- Coblentz, D., van Wijk, J., Richardson, R. M. & Sandiford, M. The upper mantle geoid: Implications for continental structure and the intraplate stress field. in vol. i 197–214 (2015).
- Sandiford, M. Why are the continents just so…? J. Metamorph. Geol. 28, 569–577 (2010).
- Kumar, A., Cacace, M. & Scheck-Wenderoth, M. Thermodynamics of continental deformation. Sci. Rep. 13, 19920 (2023).
How to cite: Kumar, A., Cacace, M., and Scheck-Wenderoth, M.: Critical crustal thickness as a reference tectonic state: a global perspective, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3527, https://doi.org/10.5194/egusphere-egu25-3527, 2025.
