| Abstrakt: |
Testing of the geochemical compositions of the Late Cenozoic volcanic rocks of Kamchatka on new discriminant diagrams confirmed the existence of different geodynamic settings at that time. Late Miocene (~6 Ma)–Pliocene volcanic rocks of Eastern Kamchatka and the Central Kamchatka Depression, as well as the Late Pliocene (~3.5 Ma)–Holocene alkaline, calc–alkaline, and adakite volcanic rocks in the central part of the Sredinnyi Range are shown to be similar to the volcanic rocks of the Pacific-type transform margins. At the same time, the Miocene–Holocene volcanic rocks of Southern Kamchatka, the Miocene–Early Pliocene volcanic rocks of the Sredinnyi Range, and the Pleistocene–Holocene volcanic rocks of Eastern Kamchatka resemble the volcanic rocks of convergent margins. In central Kamchatka (from the coast to the Sredinnyi Range), igneous complexes typical of the transform margin were formed at the end of the Miocene–Pliocene, during the collision of the Kronotsky island-arc terrane and the movement of the Pacific plate. The geochemistry of the transform-margin volcanic rocks is caused by the upwelling of the subslab asthenosphere, both into the collision zone and the zone of the Sredinnyi Range volcanic arc, following the Commander–Kronotsky microplate slab segmentation and breakoff. [ABSTRACT FROM AUTHOR] |
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