MAGMATISM AND TECTONICS OF THE NORTHEAST OF THE OCTOBER REVOLUTION ISLAND (SEVERNAYA ZEMLYA ARCHIPELAGO)

In the northeastern part of October Revolution Island (Kara terrane), supra-subduction subvolcanic and volcaniclastic rocks are described. Their Ordovician-Early Devonian isotope age (U-Pb, SHRIMP II, zircon and baddeleyite) and tectonic structure have been established. Volcaniclastic rocks yielded age at 463±3 Ma. Subvolcanic granite porphyry dated at 461-472 Ma while basalts, basaltic lava breccias and dolerite sills yielded ages at 467±16 Ma. Chemical data suggest that, the studied rocks could be formed on the active continental margin of the Ordovician-Silurian in age. Deformed rocks are intruded by Late Silurian to Early Devonian dolerite dikes (407±1, 416±1.5 Ma). A comparison is made with coeval magmatic rocks of the southern and southeastern parts of October Revolution Island.