CHROMITE MINERALIZATION IN ULTRAMAFITES OF KAMCHATSKY MYS PENINSULA (KAMCHATKA)

摘要

Peculiarities of chemical composition of the rock-forming minerals (chromospinelides, first of all) have been studied for ultramafites of Kamchatsky Mys (cape) peninsula, East Kamchatka. Obtained data, as well as isotope-geochemical dating and geochemical modeling, carried previously out, allow distinguishing three series of these rocks. The first one-abyssal peridotites originated from the low depleted mantle restites (type I); type II-the suprasubduction zone (SSZ) harzburgites originated from the highly depleted mantle restites; type III-the dunite-pyroxenite series of cumulate rocks. The latters take their origin from arc melts of boninite and, partly, tholeiite composition ad they are just associated with chromite ores. There were also revealed several stages in the Kamchatsky Mys ultramafites complex development; they correspond to different geodynamic regimes during the ophiolite formation. Each of these stages is characterized by its own type of Cr-spinel mineralization. The mere chromite ores are located in the inner parts of lens-shaped dunite bodies; they were formed as a result of interaction between host harzburgites and primitive arc melts.