Abstract:
Dolomite sandification is widespread in central Yunnan, China, where previous studies have primarily focused on sandification classification and variations in the physical and mechanical properties of dolomite rocks. However, the fundamental mechanisms responsible for dolomite sandification remain poorly understood. This study analyzed the influences of acidity, temperature, and stress on the dissolution rate of dolomite through dissolution tests. Integrating both compositional and microscopic structural changes, the micro-mechanism of dolomite sandification was then investigated. The results indicate that with the increase of dissolution temperature, stress, and pH, average dissolution rate of dolomite increases gradually. Temperature exerts the strongest influence on the dissolution rate of dolomite, followed by pH, while stress has a comparatively weaker effect. The dissolution rate of MgCO
3 in dolomite by oxalic acid is significantly higher than that of CaCO
3, and small solution pores with different sizes and uneven distribution are formed in the crystal cell structure of dolomite, resulting in microscopic differential dissolution. Additionally, dolomite contains certain components that are either insoluble or difficult to dissolve in acid, forming a skeleton with a Sakima structure that eventually disintegrates into dolomite sand by external force. Therefore, dolomite sandification represents the macroscopic manifestation of microscale differential dissolution. Elevated temperature, increased stress, and stronger acidity accelerate dolomite dissolution, enhance differential dissolution processes, and promote more extensive sandification. This study provides a scientific basis for the understanding and prevention of the sandification mechanism of dolomite in the Central Yunnan region.