Iron Accumulation and Magmatism in Early Precambrian Greenstone Belts

The Age of Sedimentary-Volcanogenic Rocks of the Chortomlyk Iron Deposit, the Middle Dnipro Domain of the Ukrainian Shield

“…Three associations of ferruginous-siliceous rocks have been identified in the greenstone belts of the Middle Dnipro Domain. These are the ferruginous-siliceous-mafic and ferruginous-siliceous-keratophyre (schist-jaspilite-tholeiite) associations in the Konka Group and the transitional ferruginous-siliceous-shale to ferruginous-siliceous-keratophyre association in the Bilozerka Group, which many researchers compare with the ferruginous-siliceous formations of Kryvyi Rih Group (Semenenko et al, 1978;Semenenko et al, 1967;Sivoronov et al, 1990). The rocks of the early ferruginous-siliceous-mafic association are a few tens of meters thick and are found among the volcanogenic rocks of the komatiite-tholeiitic association.…”

“…Metakomatiite association: 1 -complex KT-1; 2 -complex KT-2; 3 -dunite-harzburgite association; 4 -complex KT-3; 5 -complex KT-4; 6complex of shale-jaspilite-tholeiite; 7 -metadacitetho leiite-andesite association: 8 -lower complex; 9upper complex; 10 -rhyodacite and tonalite-plagioclase granite association; 11 -subvolcanic facies; 12hypabyssal facies; 13 -granite of the Tik massif; 14 -granite-gneissic basement; 15 -faults; 16geological boundaries , 1967) which is composed of sedimentary and felsic effusive rocks with subordinate basic volcanic rocks and chemogenic ferruginous-siliceous sediments. Later, these rocks were attributed to the shale-jaspilite-tholeiite association and assigned to the Konka Group (Sivoronov et al, 1990). To solve this problem, we dated detrital zircon from quartz-amphibole schists from the section of the sedimentary-volcanogenic rocks of the Chortomlyk iron deposit (drillhole 12-B) (Fig.…”