Crystallization temperatures have been calculated to evaluate the conditions of formation of the high-temperature microscopic veins and the intergrowths of brown amphibole + orthopyroxene as well as those of magmatic phases. Since the compositions of the minerals may have been changed during later-stage, lower-temperature processes, the calculated temperatures may be minimum values. Clinopyroxene and orthopyroxene temperatures were calculated with the geothermometer proposed by Lindsley and Anderson (1983) using the program written by Anderson et al. (1993), and amphibole-plagioclase temperatures were calculated with the geothermometer proposed by Holland and Blundy (1994). These calculations were made by assuming a pressure of 2 kbar, but the results are not particularly pressure sensitive. The calculated temperatures are shown in Table T10 and Figure F12.
Calculated temperatures for clinopyroxenes hosting the intergrowths near the high-temperature microscopic veins (1000°-700°C) and within the interfingering parts (1000°-840°C) are lower than those of magmatic clinopyroxenes (1200°-800°C). Temperatures of orthopyroxene blebs near the veins and in the interfingering clinopyroxenes are 1020°-820°C and are similar to those of the clinopyroxene hosting these orthopyroxene blebs. Amphibole-plagioclase temperatures for the high-temperature microscopic veins are 820°-650°C. Overall, the temperature data indicate that the interfingering textures and the high-temperature microscopic veins were formed under similar and rather high-temperature conditions up to 1000°C. One of the most important results of the temperature calculation is that the temperatures are gradational from the magmatic stage to the stage of the high-temperature microscopic vein and interfingering textures without a significant break (Fig. F12). This suggests that the penetration of the high-temperature microscopic veins and the formation of the intergrowth textures followed just after (or were coeval with the latest stage of) the magma crystallization.