Статистический петрохимический анализ габбро-монцосиенит-гранитовой формации в Среднегорской структурной зоне Болгарии

B. Kamenov, A. Andreev, S. Boyadižiev. Statistical Petrochemical Analysis of the Gabbro-Monzosyenite-Granite Formation from the Sredna Cora Structural Zone in Bulgaria. On the basis of statistical analysis of 470 silicate analyses from the intrusive complexes of the gabbro-monzosyenite-granite formation a generalized formational petrochemical characteristic is proposed. The statistical parameters of the following rock groups are determined: basic, medium-basic, medium-acid, sub alkaline and acid. The general formational features of the rock groups are discussed in detail. The comparison of oxide pairs by means of the Fisher and Student criteria showed facial differences between the plutonic and the dyke magmatites. The oxides are grouped in descending order according to the significance of the differences. The multiple means in dykes and plutonites of the formation and separately from the eastern part of the Sredna Gora zone are compared by means of the method of Hotteling. The order of significance of the oxide influence in individual rock groups is reviewed by the evaluation of the differences in the multiple case. The comagmatic relations between magmatic rocks of the plutonic and dyke stages are pointed out and at the same time some interfacial differences are found. Noted is the relatively more calcium and slightly more manganese character of almost all rock groups of the formation in comparison with the average rock types.