Досліджено геохімічні особливості, морфологію і забарвлення монациту з метасомати-тів Сущано-Пержанської зони Українського щита. Метасоматити просторово й генетично пов’язані з гранітоїдною серією Коростенського плутону. Визначено три геохімічні типи монациту; за співвідношеннями мікроелементів і віком виокремлено тип, синпетрогенний до формування метасоматитів. Результати геохімічної типізації підтверджено геохімічним моделюванням мікроелементного складу монациту, генетично пов’язаного з магматогенно-гідротермальною системою Коростенського плутону. З’ясовано, що, принаймні, у цьому випадку кореляції візуально спостережених ознак з результатами геохімічної типізації зе-рен практично нема.
We investigated monazite from various metasomatic rocks of Sushchano-Perzanska zone and granitoids of Korostenskyi pluton with which they are spatially associated and genetically linked (North-Western part of the Ukrainian Shield). We studied the geochemical characteristics of monazite, its morphology and colour.
Monazite is present in small quantities in metasomatically altered rocks, and is distributed very unevenly - in most rocks varieties (Perzhanski granites with glassed silica, quartz-feldspar metasomatites, albitites, siderophyllite-feldspar metasomati&tes) it is actually no; in significant concentrations, it is available only in Perzhanski granites (72 ppm), altered Perzhanski granites (137) and siderophyllite metasomatites (920 ppm).
We have identified three geochemical types of monazite. Grains& of the first geochemical type, most likely, are relict, because their age and composition coincide with the age and composition of monazite from Korostenski granitoids. The grains of the second type are synchronous in age with the formation of metas&omatic rocks, and the grains of the third type probably relate to the processes of later hydrothermal alteration of Perzhanski granites, which is confirmed by the pres-ence of low-temperature hydrothermal minerals in the respective rocks composition.&
We performed geochemical modelling of the composition of ore-bearing hydrothermal-metasomatic rocks using the geochemical model of the formation of the Korostenskyi pluton granitoid series.
The criteria of monazite geochemical typification have be&en developed. Defined geochemical types of the mineral reflect the lot of stages of the metasomatic rocks formation in the region. The second geochemical type of monazite corresponds to the main stage of the Sushchano-Perzhanski metasomatic rocks for&mation, which is defined by the ratio of all studied trace elements and by the obtained values of absolute age. The results of typification of monazite in colour indicate that it is impractical to typify the monazite grains on this basis during the s&tudy of metasomatic rocks (at least such that we stud-ied), although this question requires further study.
