Abstract:

The “Dolomite Problem” has been a source of contention among geologists for over two centuries and remains one of the most contentious issues in the field. To advance research on dolomite genesis, this paper employs crystal structure analysis to investigate its structural characteristics, formation environment, and evolutionary characteristics, thereby providing a basis for revealing its formation mechanism. Given the mutual influence and constraints between crystal structure and nucleation-growth kinetics, the study combines crystal structure analysis with nucleation-growth thermodynamics to analyze dolomite’s formation mechanism and conditions in detail. Results demonstrate that the crystal structure controls the mineral type, nucleation-growth rate, growth direction, and final morphology of dolomite, thus determining its thermodynamic and kinetic properties. Thermodynamic studies indicate that modern seawater exhibits a thermodynamic tendency to precipitate dolomite, and the dolomitization reaction can proceed under standard conditions. However, actual dolomite deposition in modern seawater is minimal, and the feasibility of establishing a new thermodynamic model to explain dolomite genesis requires verification through experimentation. Kinetic studies reveal that factors impeding low-temperature inorganic dolomite formation in seawater include Mg²⁺ hydration, sulfate effects, cation ordering processes, $\mathrm{CO}_{3}^{2-}$ activity, solution supersaturation, and the presence or absence of nucleation sites. Nevertheless, current understanding of these factors remains inconclusive and does not fully resolve the pivotal issue of low-temperature inorganic dolomite formation. Dolomite formation and ordering result from dissolution-recrystallization processes over geological time. In the initial stages, dolomite formation is likely controlled by nucleation kinetics, with metastable intermediate phases predominating. As the process advances, growth kinetics becomes the primary control. The development and application of advanced analytical techniques have facilitated mineralogical research at the molecular and atomic scales. Such analysis provides direction for studying dolomite formation mechanisms. We therefore recommend utilizing advanced techniques rationally, integrating crystal structure analysis and nucleation-growth thermodynamic theory, to explore dolomite crystal growth mechanisms at the atomic scale. This approach aims to furnish novel perspectives on dolomite genesis research and provide a robust theoretical and empirical foundation for potentially unraveling the enigma of dolomite formation.

Key words: dolomite genesis, crystal structure, crystal nucleation-growth, thermodynamics, kinetics