This research was conducted to analyze the greenschists from the Kranjska reber area. Eight samples were collected in the field and analyzed using various methods: optical microscopy, scanning electron microscopy, powder X-ray diffraction, illite and chlorite crystallinity, chlorite geothermometry, and thermodynamic modeling of pseudosections. Based on the analytical results, it was possible to determine the mineral compositions of the samples and to estimate the temperature–pressure conditions of rock formation.
It was established that the main minerals present in the samples are quartz, chlorites, plagioclases, and white micas, with stilpnomelane and actinolite also present in some cases. Samples KR 2-1, KR 2-2, KR 2-3, and KR 3 were mineralogically and structurally very similar to one another, whereas KR 1, KR 4-1, KR 4-2 and KR 5 differed significantly from each other. This was also confirmed by the cluster analysis of the samples X-ray diffractograms. The plagioclases were classified within the albite range, the chlorites between chamosite and in some cases clinochlore, and the white micas within the phengite range. The illite and chlorite crystallinity methods showed that the samples reached the epizone grade, while chlorite geothermometry indicated a range of estimated temperatures from a minimum of 150 °C to a maximum of 455 °C.
The results of the analyses of chlorite geothermometry, illite crystallinity and thermodynamic modeling, consistent with previous studies of the Kranjska reber greenschists, confirm a low degree of metamorphism within the greenschist facies. Mineralogical and temperature variations indicate heterogeneity of the protolith and local differences in metamorphic conditions within the studied area, as well as not reaching the complete thermodynamic equilibrium of rocks during metamorphism.
|
