Tonalite-throndemite-granodiorite (TTG) associations of the middle Dnieper Archean craton

Plagiogranites comprize about 70% of whole area of the Middle Dnieper craton (MDC) which is situated in the megablock of the Ukrainian Shield (USh) of the same name. They form dome or swell-like structures distributed between the set of greenstone belts (structures) of synclinal morphology. Some authors treat these plagiogranite as typical formations of tonalite-trondhemite-granodiorite (ÒÒG) associations/series though such term do not receive wide usage among ukrainian researchers. The aim of this publication is the desription of amount and general features of TTG associations of MDC and their comparative analysis with similar Archean formations of world known cratons. On their composition and general features, archean plagiogranites of MDC are generally similar to TTG associations of the world. Plagiogranites of Dnepropetrovsk, Saksagan and Sura complexes ar thought to be treated as typical TTG associations of the Middle Dnieper area. But hypabissal and volcanogenic rocks which comprize small massifs or subvolcanic bodies and dikes found within greenstone structures; migmatized supracrustal rocks of different composition ranging from basic to felsic varieties; microclime-rich varieties of plagiogranites; bifeldspar granitoids which commonly occur among plagiogranites with subtle and gradual transitions to them should be excluded. Some affinity established between plagiogranites of Dnepropetrovsk, Saksagan and Sura complexes is proved by heir common petrographic features, chemical and mineralogical composition as well as similar distribution patterns of admixture-elements. Comprehensive review of published data available makes it possibity to conclude that plagiogranites of these complexes are formed during the age interval of 3,1-2,9 bln years. Geologically several events of magmatic activity have been established but their certain ages are not still finally determined. The problem of identification and reliable mapping of plagiogranite ÒÒG associations of MDC requires more comprehensive and detailed investigation with using both common and more precise (up to date) analytycal methods.