НОВЫЕ ИЗОТОПНО-ГЕОХИМИЧЕСКИЕ ДАННЫЕ ПО КАЙНОЗОЙСКОМУ ВУЛКАНИЗМУ И ГЕОДИНАМИКЕ ПОДВОДНОГО ХРЕБТА ВИТЯЗЯ (ТИХООКЕАНСКИЙ СКЛОН КУРИЛЬСКОЙ ОСТРОВНОЙ ДУГИ)

Abstract

Original analytical data on rare elements and radiogenic Nd and Pb isotopes in volcanic rocks of the Southern and southwestern part of the Northern Plateau of the underwater Vityaz Ridge are presented. Interpretation of these data and a comparative analysis with published materials on volcanic rocks from the southern and northern parts of the Kuril Island Arc (KOD), which formed on two basement blocks of different genetic nature, allow us to draw the following conclusions. The tholeiite varieties of volcanic rocks of the Southern Plateau and the southern part of the KOD have similar isotope-geochemical features, which point at the general geodynamic conditions of formation and the identical degree of influence of low-temperature fluid on magma-generating processes. The geochemistry of the volcanic rocks of the Northern Plateau, which are mainly represented by subalkaline varieties, indicates a more pronounced participation of the mantle component in magmagenesis and a greater degree of influence of high-temperature melt compared to the rocks of the Southern Plateau, but less compared to the rocks of the northern part of the arc. The volcanics of both plateaus are derivatives of a single mantle source, the MORB of the Indian Ocean (Indian MORB), and were formed together with the rocks of the southern part of the KOD within the lithospheric block transformed by tectonomagmatic processes that accompanied the opening of the Kuril Basin.