Kaersutitis in Azov Area Rocks (Ukrainian Shield): Petrological Aspect
Authors:   M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine, Gatsenko V.O. , Kurylo S.I. ,   Earth Science Institute, Slovak Academy of Sciences
Published: December 2021

The paper presents the results of new studies of kaersutites from lamprophyres of the Pokrovo-Kyriivo massif (PKM) of the Azov area (Ukrainian Shield). The comparison of mineralogical-petrographic and chemical features of kaersutites of lamprophyres with those of other dyke (microgabroid) and plutonic (pyroxenite) rocks of PKM is carried out and also, with this mineral from the camptonites of the Khlibodar quarry and the pyroxenites of the Chomutov massif. The paper presents the results of new studies of kaersutites from lamprophyres of the Pokrovo-Kyriivo massif (PKM) of the Azov area (Ukrainian Shield). The comparison of mineralogical-petrographic and chemical features of kaersutites of lamprophyres with those of other dyke (microgabroid) and plutonic (pyroxenite) rocks of PKM is carried out and also, with this mineral from the camptonites of the Khlibodar quarry and the pyroxenites of the Chomutov massif. The crystal chemical characteristics of the studied kaersutites were compared with those of other amphiboles in the Azov area. According to the chemical composition of kaersutites, the conditions of kaersutite formation in the mafic rocks of the Azov area region were estimated. Microprobe studies of the chemical composition of kaersutites from kaersutite lamprophyres were performed on JXA- 8520F (JEOL) X-ray microanalyzer equipped with five wave dispersion spectrometers (WDS) at the Institute of Natural Sciences of the Slovak Academy of Sciences (Bysterka Branch). The main characteristics of the chemical composition of kaersutite from kaersutite lamprophyres of PKM are low content of TiO2 (0.5-0.68 f.o.) and Al2O3 (up to 11.4%). Due to the low Al2O3 content, they are similar to kaersutites from afir gabroid and pyroxenite PKM. Kaersutites from other rocks of the Azov area are characterized by a higher content of Al2O3 (more than 12.3%, more often — 13%). The sample of kaersutites from PKM lamprophyres is not homogeneous, which indicates fluctuations in the conditions of rock formation. Most of the studied kaersutites of the Azov area are characterized by #Mg higher than 0.55. The exception is the measured ferrokaersutite from Hlibodarivka camptonite megacrysts (# Mg = 0.43). The vast majority of Azov area kaersutites have a high alkali content (more than 3%). According to their crystal chemical characteristics, kaersutites of the Azov area region differ significantly from other amphiboles of the district. The most highly baric are ferrokaersutites from Hlibodarivka camptonite megacrysts and kaersutite from porphyry amphibole-titanomagnetite microgabrroid PKM. The formation of kaersutite from the mafiс rocks of the Azov area corresponds to the conditions of high oxygen fugacity. Ferrokaersutite from Hlibodarivka camptonite was formed under conditions of medium oxygen fugacity. Keywords: kaersutite, lamprophyre, mafic dyke, pyroxenites, the Pokrovo-Kyriivo massif, camptonites of the Khlibodar quarry, Azov area.