PETROLOGY OF LAYERED KOMATIITE LAVA FLOWS FROM THE KOSIVTSEVSKAYA GREENSTONE STRUCTURE (UKRAINIAN SHIELD)

In the lower part of Kosivtsevskaya greenstone structure 16 lava flows have been recognized that possessing the basic compositional and text ural features of layered komatiite lava flows. Lava flows consist of t hree zones: spinifex textured (A), massive porphyri-type rocks or tran sitional (B), basal cumulative (C). The chemical compositions of the l ava flows rocks are intermediate between the uncommon Barberton one an d most widespread rocks of komatiite series from other regions. At the same time the high FeO content is the specific feature of komatiites studied. The bulk composition of the lava flows rocks allows us to pro pose flows formation due to differentiation of lavas contained up to 1 0% of olivine at the moment of eruption.