Zircon age of metarhyodacite of the aleksandrovsk suite of the mykhailivka series (megablock KMA)

The LA-ICP-MS U-Pb method has been used to define the Palaeoarchaean (3264 ± 7 Ma) age of zircon from metarhyodacite Aleksandrovsk Suite Mykhailivka Series (the southeastern part Tim-Yastrebov structure Kursk Magnetic Anomaly (KMA)). According geochemical data, primary melt probably developed in a crustal magmatic source due melting older felsic rocks. closely resemble composition felsic, igneous A-type granites, formed continental rift or hot spot settings. studied was association with plume emplacement into tonalitic basement during initial stage development greenstone belts KMA megablock. It high potassium content (up 6.20 weight %), XFe ratio 0.67), low Sr content, and HFSE REEs. They are enriched light REEs, while heavy REEs undifferentiated. metarhyolite shows highly negative Eu anomaly (Eu/Eu* = 0.5). In contrast, younger, Mesoarchean (ca. 3.12 Ga) metavolcanic rocks Dichnya KMA, which close their chemical TTGs, were generated via partial mafic at vanishing mantle plume.