Приводятся новые данные о строении подводных вулканов, гайотов и вулканических островов западной части Тихого океана, полученные в рамках интеграции ученых различной специализации академической, вузовской и отраслевой науки в области наук о Земле при проведении комплексных геолого-геофизических исследований в 2015-2016 гг.

The paper presents geological and geochemical characteristics of Cretaceous guyots of Marcus-Necker intraplate rise in the Pacific Ocean. Comparison of guyots located in different parts of the extended system revealed significant differences in their geochemical characteristics, which suggest lateral and (or) vertical mantle heterogeneity in the region. The studied volcanic rocks belong to the alkaline series. In some cases, they exhibit low values of Na2O/K2O. This volcanism is not typical for most of intraplate ocean rises. No consistency is observed between volcanic rock composition of guyots, their age and (or) geographic position. A complex pattern of magnetic anomaly lineations and irregular location of seamounts of different age cause difficulties in applying hot spot model to explain the formation of this intraplate magmatic province. The location of seamounts in the structure of the rise system and the entire system in the structure of the Pacific Ocean does not contradict the formation of fault zones, which initiate melting of upper mantle geochemically inhomogeneous substrate and lead to the formation of intraplate rises. Deep fluid flows may cause a large-scale melting of the upper mantle.

Сформулированы и приведены авторские определения терминов: катастрофическое вулканическое извержение (КИ), катастрофическое суперизвержение (КСИ), разноранговые и разнотипные эпизоды и этапы вулканического катастрофизма (ВК). Все извержения разделены на 3 класса по объему и весу выброшенного и перемещенного (ювенильного и резургентного) материала, независимо от его химического состава: I класс – ≥0.5 км3; II – >5 км3 и III, суперизвержения, – >50 км3. Охарактеризованы типы и разновидности КИ и КСИ, большинство которых – главные компоненты выделенных эпизодов и этапов ВК. Рассмотрены, в первую очередь, катастрофические события XIX–XXI веков не только Курило–Камчатского региона, но и других вулканических областей. Эти детально изученные современными методами извержения могут служить приближенными моделями для реконструкций подобных событий в прошлом, особенно в части их динамики, продуктивности и катастрофических последствий.

The origin of diamonds in the lava and ash of the recent Tolbachik eruption of 2012–2013 (Kamchatka) is enigmatic. The mineralogy of the host rocks provides no evidence for the existence of the high pressure that is necessary for diamond formation. The analysis of carbon isotope systematics showed a similarity between the diamonds and dispersed carbon from the Tolbachik lava, which could serve as a primary material for diamond synthesis. There are grounds to believe that the formation of Tolbachik diamonds was related to fluid dynamics. Based on the obtained results, it was suggested that Tolbachik microdiamonds were formed as a result of cavitation during the rapid movement of volcanic fluid. The possibility of cavitation-induced diamond formation was previously theoretically substantiated by us and confirmed experimentally. During cavitation, ultrahigh pressure is generated locally (in collapsing bubbles), while the external pressure is not critical for diamond synthesis. The conditions of the occurrence of cavitation are rather common in geologic processes. Therefore, microdiamonds of such an origin may be much more abundant in nature than was supposed previously.