Estimating Influence of Crystallizing Latent Heat on Cooling-Crystallizing Process of a Granitic Melt and Its Geological Implications

Abstract: Based on the theory of thermal conductivity, in this paper we derived a formula to estimate the prolongation period (Δt_L) of cooling‐crystallization process of a granitic melt caused by latent heat of crystallization as follows: where T_M is initial temperature of the granite melt, ^T_C crystallization temperature of the granite melt, C_p specific heat, Δt_col cooling period of a granite melt from its initial temperature (T_M) to its crystallization temperature (T_C), Q_L latent heat of the granite melt. The cooling period of the melt for the Fanshan granodiorite from its initial temperature (900°C) to crystallization temperature (600°C) could be estimated ?210,000 years if latent heat was not considered. Calculation for the Fanshan melt using the above formula yields a Δt_L value of ?190,000 years, which implies that the actual cooling period within the temperature range of 900°‐600°C should be 400,000 years. This demonstrates that the latent heat produced from crystallization of the granitic melt is a key factor influencing the cooling‐crystallization process of a granitic melt, prolongating the period of crystallization and resulting in the large emplacement‐crystallization time difference (ECTD) in granite batholith.