Greenstone and Ophiolitic Belts in the Southern Part of East Siberia

Based on analysis of geologo-structural setting and petrochemical composition of ultrabasic and basic complexes of the rocks situated at the conjunction of the Siberian Craton and its folded fringing, the author comes to the conclusion that many of such complexes from this region are part of either reprocessed greenstone or later ophiolitic belts. The former are inherent in outcrops of the old craton (Sharyzhalgai Protrusion), and the latter form a series of successively adjacent belts in later mobile constructions (Baikal folded region). The greenstone belts are inherent in only Archean cratons, while the ophiolitic belts are repeated many times in the Earth’s history. Ultrabasic rocks in these belts essentially differ in their petrochemistry: the greenstone belts are represented by Fe-rich varieties while the ophiolitic belts contain Mg-rich Alpine-type rocks.