This work simulates the dynamic crystallization process of the potassic phonotephritic lava from Laoheishan volcano, Wudalianchi at different cooling rates from 1150 degrees C to 700 degrees C. The relationship between crystal crystallization characteristics and cooling rate was studied from three aspects, namely, crystal size, crystal number and crystal morphology. The results show that: (1) The crystal size distribution (CSD) reveals that the relationship between crystal size and number density at the seven cooling rates show the characteristics of good power law. The exponent of power law is almost the same, ranging from 3. 69 to 4. 42, as indicates that the crystal size distribution does not significantly depend on the cooling rate. (2) As the cooling rate decreases from fast to slowly, the total number of crystals generally grows. When the cooling rate is 0. 0468 degrees C/min, the number of crystals reach a peak. Then, the crystals enter the Ostwald ripening process, and the crystallization is mainly the process of annealing and merging until the kinetics reaches equilibrium. (3) The crystal morphology has fractal characteristics at various cooling rates, and the fractal dimension is between 1. 39 and 1. 62. The complexity of crystal boundary at different cooling rates shows large random fluctuations, which reveals the strong sensitivity of crystal morphology to the cooling rate. When the cooling rate reaches 0. 0468 degrees C/min, the complexity of crystal boundary tends to be stable. The internal correlation between crystallization characteristics and cooling rate is of scientific significance for realizing the movement mechanism of lava flows in Laoheishan volcano and their dynamic crystallization mechanism.
