Composition and geodynamic settings of formation of titanium-bearing ultrabasic-basic massifs in the Central-Asian fold belt

Geological, mineralogical, and geochemical studies showed that all high-Ti ultrabasic-basic massifs are subdivided into two groups. The first group is island-are anorthosite-pyroxenite-gabbro massifs. In contents and patterns of REE they are similar to high-alumina low-alkali low-Ti peridotite-gabbr o massifs of paleosubduction zones. The mutual arrangement of massifs of lo w- and high-Ti gabbroids permits reconstruction of both the strike and the direction of subsidence of paleosubduction zones in deeply eroded folded ar eas. The second group of high-Ti gabbroids involves peridotite-pyroxenite-g abbro and syenite-clinopyroxenite-gabbro massifs, which are similar in geoc hemical composition to basalts of plume nature and are the products of with in-plate basic magmatism. High-Ti massifs occur in oceanic, collisional, an d intracontinental settings.