Chemical effect of differential stress and its implication on metamorphism and partial melting

Mechanochemical study have shown that mechanical forces can directly affect chemical bonds and bias reaction pathways.

Quantum chemistry calculations and molecular simulations on the gas generation mechanisms of coals indicated that shear stress can directly affect the six-membered ring structure and cause rupture, resulting in structural defects that are unlikely to occur under thermal activation (Xu et al., 2015; Hou et al., 2017; Wang et al., 2017, 2019, 2021). The results also indicate that the creation of structural defects involves energy absorption and the conversion of mechanical energy into internal energy (Han et al., 2016, 2017). The aromatic rings can rotate more easily than the bond stretching under stress (Wang et al., 2019).

Combined with the Tersoff potential, molecular dynamics simulation on the shear deformation process of two α-quartz crystals show that the crystal model primarily exhibits atoms flowing and changing in the direction of chemical bonds during the steady-state flow stage at 600 K (Sun et al., 2025). The molecular potential energy and stress vary in an oscillating up-and-down curve during shear, indicating that chemical energy can be stored and released during plastic deformation.

Studies from the mechanochemistry and tectonic stress chemistry indicate that the differential stress may influence the metamorphism and also the mechanism of the partial melting of the subduction plate.

 

References:

• Han, Y., Xu, R., Hou, Q., Wang, J., and Pan, J., 2016, Deformation Mechanisms and Macromolecular Structure Response of Anthracite under Different Stress: Energy & Fuels, v. 30, no. 2, p. 975-983.
• Han, Y., Wang, J., Dong, Y., Hou, Q., and Pan, J., 2017, The role of structure defects in the deformation of anthracite and their influence on the macromolecular structure: Fuel, v. 206, p. 1-9.
• Hou, Q., Han, Y., Wang, J., Dong, Y., and Pan, J., 2017, The impacts of stress on the chemical structure of coals: a mini-review based on the recent development of mechanochemistry: Science Bulletin, v. 62, no. 13, p. 965-970.
• Sun, J., Guo, Q., and Hou, Q. 2025. Molecular dynamics simulation of quartz deformation under slow earthquake background: SCIENCE CHINA Earth Sciences. DOI: https://doi.org/10.1007/s11430-024-1469-0.
• Wang, J., Guo, G., Han, Y., Hou, Q., Geng, M., and Zhang, Z., 2019, Mechanolysis mechanisms of the fused aromatic rings of anthracite coal under shear stress: Fuel, v. 253, p. 1247-1255.
• Wang, J., Han, Y., Chen, B., Guo, G., Hou, Q., and Zhang, Z., 2017, Mechanisms of methane generation from anthracite at low temperatures: Insights from quantum chemistry calculations: International Journal of Hydrogen Energy, v. 42, no. 30, p. 18922-18929.
• Wang, J., Hou, Q., Zeng, F., and Guo, G., 2021, Stress Sensitivity for the Occurrence of Coalbed Gas Outbursts: A Reactive Force Field Molecular Dynamics Study: Energy & Fuels, v. 35, no. 7, p. 5801-5807.
• Xu, R. T., Li, H. J., Hou, Q. L., Li, X. S., and Yu, L. Y., 2015, The effect of different deformation mechanisms on the chemical structure of anthracite coals: Science China: Earth Sciences, v. 58, no. 4, p. 502-509.