SM-ND ISOTOPE SYSTEM OF THE ANORTHOSITE- GRANITE ASSOCIATION OF THE UKRAINIAN SHIELD (THE KOROSTEN' BLOCK)

Abstract

This paper presents the results of an Sn-Nd isotope investigation of rocks from the anorthosite-granite association of the Ukrainian Shield. Geological data suggest that this association is the latest in the series of autonomous anorthosites and is unique in the variety and ratios of the constituent rocks, since its anorthosites are associated with large bodies of rapakivi granite. The specimens were collected from the Korosten' block, the rocks in which break through the early Proterozoic metamorphic formation of the Teterev series (amphibolite, gneiss and metasediments) on the northwest part of the Ukrainian Shield. This block is a complex igneous body whose first phase comprises mafic rocks, while the second consists of several types of rapakivi granite. Four specimens of mafic rocks were studied (4GL-73 anorthosite, 5SL-73, U-64 and U-73 gabbro-anorthosites: 4GL-73 and U-64 from the Golovino opencuts and 5SL-73 and U-73 from Slipchitsy); and one specimen of rapakivi granite (K3, 4 from the Bubets opencut near Malina). Study results are discussed.