PECULIARITIES OF THE ULTRABASIC MINERALOG Y - CRITERION OF PALEOGEODYNAMIC CONDITIONS OF OPHIOLITE FORMATION IN THE ALTAI-SAYAN FOLDED AREA

New data are reported on the composition of ophiolite ultrabasite mine rals from the Altai-Sayan folded area (ophiolite associations from the Altai Mountains, Kuznetsk Alatau, West Sayan, and South Tuva). Peculi arities of the mineral compositions show that ultrabasic rocks are rep resented by two types - mantle tectonites and cumulates. Comparative a nalysis of studied utrabasite mineralogy and rocks of modern objects p ermit us to clear up paleogeodynamic environments under which ophiolit es were formed. These environments appeared to be similar to the setti ngs in the Western Pacific Ocean.