GRANITOIDS OF THE ZACHATIVKA-FEDORIVKA ANTICLINE IN THE MANGUSH SYNCLINORIUM: GEOCHEMICAL FEATURES, ORIGIN, AND AGE (AZOV DOMAIN OF THE UKRAINIAN SHIELD)

Abstract

The Paleoproterozoic crust formation in the Azov domain remains underexplored. In the Neoarchean-Paleoproterozoic, the Azov segment of the Archean crust was fragmented by large rift structures. This stage is associated with the formation of Neoarchean-Paleoproterozoic sedimentary-volcanic complexes of the Central Azov Series (2.76-2.22 Ga) and extensive granitoid magmatism. The research aimed at studying granitoid intrusions in the Zachativka-Fedorivka anticline in the Mangush synclinorium of the Central Azov region from the geochemical perspective. Granitoids of the Zachativka-Fedorivka anticline in the Mangush synclinorium include granitoids and later pegmatoidal granites. Plagiogranitoids are moderate-potassium rocks of the K-Na series, with predominance of Na2O over K2O and low Rb/Sr ratio (0.03). They are divided into plagiogranites with low contents of HFS elements and positive europium anomalies and granodiorites with higher contents of HFS elements and predominantly negative europium anomalies. The U-Pb age of titanite from granodiorites is 2028±47 Ma. This age corresponds to the closure of the U-Pb isotope system of titanite and thus reflects the minimum age of granodiorite. The 207Pb/206Pb age of zircon from granites is 2.07-2.09 Ga. The formation of the Paleoproterozoic granitoids of the Central Azov may be related to the activization of the mantle beneath the Azov domain during the formation of the East Sarmatian orogen at ca. 2.1 Ga. They could have formed because of partial melting of the lower crust because of underplating of mafic melts. The 2.05 Ga old vein bodies of pegmatoidal subalkaline granites, were probably formed at the stage of collision of the Sarmatia and Volga-Ural continents.