FRACTAL ANALYSIS OF AMPHIBOLE AGGREGATION GROWTH FROM A BASALTIC MELT AND RESIDUAL MELT AT HIGH PRESSURE AND HIGH TEMPERATURE

摘要

The aim of this work is to quantitatively explore the texture evolution of amphibole aggregation and residual melt with pressure and temperature. The amphibole aggregation growth from a basaltic melt and the residual melt at high pressure (0.6-2.6 GPa) and high temperature (860-970 degrees C) exhibit statistical self-similarity which made us consider studying such characteristic by fractal analysis. The bi-phase box counting method was applied for fractal analysis of each product to identify the fractal phase and the fractal dimension was estimated. In the experimental products, the residual melt is identified as the fractal and amphibole as the Euclidean except for one experiment. The results show that the residual melt can be quantified by the fractal dimension (D-B) within the range of 1.782-1.848. The temperature has a significant effect on the morphology of amphibole arid the fractal dimension of the residual melt. The higher the crystallization temperature is, the more regular the amphibole grains are. At lower temperature (from 860 degrees C to 915 degrees C), the fractal dimension of the residual melt decreased with the increasing crystallization temperature, but at higher temperature (970 degrees C), the fractal phase changed to amphibole and the fractal dimension of amphibole is 1.816. The pressure may be the dominant factor that controls the morphology of the mineral aggregation and the residual melt. The fractal dimension of melt decreased linearly with the increasing pressure and if the linear relationship between the fractal dimension and pressure can be further verified in the future, it can be used as a potential geological barometer.