New Data on the Structure and Composition of Gabbroids and Plagiogranites from the Late Cretaceous Ophiolitic Complex of the Kamchatsky Mys Peninsula (Eastern Kamchatka)

摘要

The study of ophiolites as analogues of the ancient oceanic crust is hampered by the tectonic disintegration of rock complexes, which usually constitute separate tectonic sheets and blocks within a serpentinized melange. Paleotectonic settings of ophiolites are commonly indicated by ultramafic and basaltic rocks, although adequate interpretation of them is possible only if based on the entire spectrum of ophiolitic rocks. This communication presents new petrological, miner-alogical, and geochemical data on gabbroids and pla-giogranites that form a large massif within a serpen-tinite melange in the southern Kamchatsky Mys Peninsula. In [1], we assumed that the Late Cretaceous ophiolitic complex includes these gabbroids along with highly depleted peridotites of Mt. Soldatskaya and island-arc tholeiites and boninites of the Tarkhov Formation [1]. Dolmatov [2] discovered acid rocks in this region, and a brief description of them is given in [3].