LIFETIME OF SUPERHEATED WATER IN A MICROMETRIC SYNTHETIC FLUID INCLUSION

摘要

A synthetic pure water fluid inclusion showing a wide temperature range of metastability (T_h - T_n ≈ 50°C; temperature of homogenization T_h =144°C and nucleation temperature of T_n = 89°C) was selected to make a kinetic study of the lifetime of an isolated microvolume of superheated water. The occluded liquid was placed in the metastable field by isochoric cooling and the duration of the metastable state was measured repetitively for 7 fixed temperatures above Tn. Statistically, metastability lifetimes for the 7 data sets follow the exponential reliability distribution, i.e., the probability of non nucleation within time t equals e~(-λt). This enabled us to calculate the half-life periods of metastability τ for each of the selected temperature, and then to predict T at any temperature T > T_n for the considered inclusion, according to the equation τ(s)=22.1 x e~(1.046xΔT), (ΔT = T - T_n). Hence we conclude that liquid water in water-filled reservoirs with an average pore size≈10~4 μm~3 can remain superheated over geological timelengths (10~(13)s), when placed in the metastable field at 24°C above the average nucleation temperature, which often corresponds to high liquid tensions (≈-50 MPa).