NEW DATA ON THE STRUCTURE AND COMPOSITION OF GABBROIDS AND PLAGIOGRANITES FROM THE LATE CRETACEOUS OPHIOLITIC COMPLEX OF THE KAMCHATSKY MYS PENINSULA (EASTERN KAMCHATKA)

Abstract

The complex petro-, geochemical and mineralogical investigation of gabbroides and associating with them plagiogranites permits to conclude that formation of the gabbroic pluton, which fragments are mapped in 1-ya Olchovaya river headwater, proceeded under per-subduction conditions within the island arc system. Apparently gabbroides and plagiogranites are derivatives of the island-arc toleite melts. The conducted study confirms the validity of uniting gabbroides and plagiogranites in the integral ophiolite complex with highly depleted peridotites of Soldatskaya mountain massif and island-arc toleitic basalts and boninites of Tarchov suite. Gabbro-plagiogranite pluton is a fragment of the bedding of upper-Cretaceous Kronot early island arc.