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This paper reports results from a study of two new genetic types of diamond discovered in Kamchatka. These diamonds were formed under extra-mantle conditions, as can be inferred from the fact that there is no indication of post-crystallization annealing with the formation of aggregated nitrogen defects in them. The first of these types is defined by us as volcanic-atmoelectrogenic. This is formed directly in a volcanic ash-gas cloud due to deep-seated methane released by atmospheric electric discharges. The second genetic type of diamonds is formed at depth within a magmatic-pneumatolytic-hydrothermal ore deposit, and can be defined as the explosive-tuffisite type. The industrial potential of these types enables us to assert the discovery of a new diamondiferous province, i.e., the Kamchatka Province. [ABSTRACT FROM AUTHOR]

Comprehensive mineralogical and geochemical studies were conducted in application to a representative sample of tephra from Cumbre Vieja Volcano (the 2020–2021 eruption). The tephra has a gravel-psammitic grain-size distribution, and is characterized by an anomalously high degree of particle vesicularity. The whole-rock composition of this tephra is consistent with the transition from alkaline picrobasalts to alkaline basalts, while being essentially different from the tephra ashes discharged by marginal continental volcanoes. The tephra was studied to detect 45 trace elements with whole-rock compositions occasionally reaching 2333 g/t, above the respective figure for the tephra of island arc volcanoes. Judging by the relationship among geochemical criteria, the Cumbre Vieja tephra is consistent with the average parameter values for intraplate volcanoes in oceans. One geochemical feature of this tephra consists in a strong enrichment in lanthanoids, as well as in noble and platinoid metals. The lithogenic gas phase which was obtained by heating the tephra sample was found to contain H2, CO, CO2, H2O, CH4, C2H4, C2H6, C3H6, and С3H8. The proportions among inorganic components in the gas phase as a whole correspond to the boundary region between crustal and mantle–crustal derivates, but water is in relatively low amounts. Microlites were found to contain Fo73–84 olivine; this contains dominantly diopside clinopyroxene, andesine–bytownite plagioclase, chrome-spinellids, phase-homogeneous solid solutions of ilmenite in magnetite, phases of Ni-Cu bearing native iron, quartz, and sodic hydroxyl-chlorides. In addition, the Cumbre Vieja tephra was found to contain dispersed scattered carbonaceous material with δ13СPDB = –30...–24‰ as the isotopic composition of carbon, which is consistent with the isotopic composition of carbon in abiogenic carbonaceous materials of volcanogenic origin. The entire set of results of these mineralogical and geochemical studies characterizes Cumbre Vieja Volcano as a typical intraplate-oceanic plume volcano. [ABSTRACT FROM AUTHOR]

The upper Sandbian, Katian, and Hirnantian complexes of conodonts in the upper Ordovician section of the western slope of the Southern Urals near the village of Nabiullino were studied. The δ13C positive excursion with a maximum of 3.3‰ associated with the global Hirnantian isotopic event, HICE, was fixed for the first time. This excursion shows the beginning of the Hirnantian stage in the terrigenous-carbonate section of the upper Ordovician in the Southern Urals. It coincides with the first occurrence of the Hirnantian conodont species of Gamachignathus ensifer and the conodonts of shallow-water biophacies, Aphelognathus-Ozarkodina, reflecting the global glacio-eustatic event. [ABSTRACT FROM AUTHOR]

This paper reports a study of xenoliths sampled in marine sedimentary carbonate rocks in fumaroles of the crater zone in the Second Cone of the GTFE (Great Tolbachik Fissure Eruption) North Vent. These rocks have been subjected to the action of the GTFE exhalative pneumatolytic fluids, resulting in carbonates giving rise to numerous compounds with mixed carbonate-sulfate-chloride anion radicals, which are treated as two interclass and nine intertype crystal-chemical hybrids. The patterns identified in the altered micro xenoliths, which consist in inhomogeneities of mineral paragenesis, are treated here as resulting from successive epigenetic transformation of the original carbonates to, at first, sulfate carbonates, then to carbonate sulfates, and subsequently to chloride-carbonate-sulfates and chlorides. Judging by an absence of signs of phase heterogeneity, the crystal-chemical hybrids studied here are homogeneous solid-phase mixtures of carbonates, sulfates, and chlorides in varying proportions. The carbonates in the micro xenoliths have isotopic compositions of carbon (δ13СPDB = –5.34 ± 0.62‰) and oxygen (δ18OSMOW = 24.09 ± 1.05‰) that are consistent with carbonates to be found in marine sedimentary limestones that were redeposited during volcanogenic transportation. The sulfate sulfur has the isotopic composition (δ34S = 1.5–2‰) varying within the range of variation established for sulfates of volcanogenic origin. In the carbonaceous particles associated with micro xenoliths, the isotopic composition of carbon (δ13CPDB = –27.37 ± 2.97‰) and of nitrogen (δ15NAir = 6.74 ± 2.48‰) tend toward the mode in the distribution of these values in the ejecta of present-day continental volcanism. The crystal-chemical hybrids identified here furnish a typomorphic criterion for the exhalation fumarole facies and are treated as a previously unknown phenomenon of present-day volcanism. [ABSTRACT FROM AUTHOR]

Our multidisciplinary petrologic, mineralogical, and geochemical studies of volcanic material sampled from three chronologically discrete, but successive, ash discharges during the period from November 30, 2020 to January 18, 2021 were concerned with grain-size inhomogeneity, chemical and mineral phase composition, the concentrations of trace elements, the isotopy of Sr, Nd, and carbon, and with the composition of inorganic and organic lithogenic gases. For the first time volcanic ashes were found to contain eskolaite, mantle spinellids of the magnetite–magnesioferrite composition, hybrid compounds of Ca–Zn-carbonates with titanium formate, and polycomponent metallo-organic compounds. The net result was to obtain proof of a mantle–asthenosphere origin of the ash material and to identify a previously unknown pattern consisting in a conjugate temporal orderliness in the variations of many properties in the material sampled from the explosions. This seems to reflect the evolution of the melt in the mantle magma chamber. [ABSTRACT FROM AUTHOR]

Ejecta of recent volcanic eruptions were found to contain a carbonaceous mineral phase paragenesis of explosive atmospheric electrogenic origin. The paragenesis involves diamonds of octahedral habitus with non-aggregated nitrogen defects (without signs of mantle burning), disordered graphite, shungite-like bitumen (kerite–anthraxolite), carbonaceous globules (clustered allotropes of dicarbon composition), metal carbon nano-microcomposites resulting from thermal impact decomposition of metal organic compounds, and abiogenic organic compounds. The carbonaceous paragenesis identified here is considered as a unique natural phenomenon that indicates the existence of a global process that favor endogenous carbonization of the Earth's crust during crust–mantle interactions. [ABSTRACT FROM AUTHOR]