HOT SPOT VOLCANOES (NEW EXHIBITION AT THE EARTH SCIENCE MUSEUM AT MOSCOW STATE UNIVERSITY)

The new exhibition is located in Hall 5 «Geotectonics» in the Earth Science Museum at Moscow State University and devoted to an urgent problem of volcanic manifestations in areas of hot spots. Among the large number of active volcanoes on our planet, a significant place is occupied by volcanoes of hot spots and mantle plumes, which are characterized by the eruption of a huge amount of pyroclastic material (Hawaii, Yellowstone) and often form large igneous provinces (Eastern Siberia, Kerguelen, Deccan, Iceland). The exhibition presents geological samples from the funds and collections of the museum staff. All samples are characteristic of hot spot volcanoes and mantle plumes from different regions of the world.

Tectonic-sedimentary system of the Atlantis-meteor seamounts (North Atlantic): late Miocene to Pliocene volcanic and sedimentary environments and the position within the Atlantic-arctic structures

The article concerns the original materials obtained in the 33-rd cruise of the R/V Akademik Nikolai Strakhov in the eastern part of the North Atlantic while studying the system of AtlantisMeteor seamounts. The system is a single volcanic uplift formed on the Canary Abyssal Plate, and is one of the key objects for understanding the geological history of this segment of the Atlantic Ocean. The article discusses basalts, tefrites, and organogenic-terrigenous lagoon-marine sediments dredged from the Atlantis, Plateau, and Cruiser seamounts. The petrographic properties and compositions of the basalts of the seamounts Atlantis and Cruiser reflect significant differences in the environments of their effusions. In the first case, well-crystallized, not showing signs of vesicularity, olivine basalts poured out in deep-water conditions. Glassy highly vesicular basalts from the Cruiser seamount are characteristic of shallow subaerial effusions. Evidence has been obtained in favor of the subaerial settings of the accumulation of tefrites from the Plato seamount. The regularities of lithogenetic transformations of organogenic-terrigenous deposits of the Cruiser seamount, exposed to high-temperature effects of subaerial lava flows, are revealed. In the course of volcanogenic-sedimentary lithogenesis, the lignite-like material lost its primary structure, turning into natural anisotropic coke with a wide development of fusinite and pyrofusinite. The authors of the article associate the studied volcanic manifestations with the final (Late MiocenePliocene) stage of volcanism in the seamount system, which preceded the disintegration of the system, its progressive immersion and the transformation of islands into guyots.

Global geological methane emissions: An update of top-down and bottom-up estimates

A wide body of literature suggests that geological gas emissions from Earth’s degassing are a major methane (CH4) source to the atmosphere. These emissions are from gas-oil seeps, mud volcanoes, microseepage and submarine seepage in sedimentary (petroleum-bearing) basins, and geothermal and volcanic manifestations. Global bottom-up emission estimates, ranging from 30 to 76 Tg CH4 yr–1, evolved in the last twenty years thanks to the increasing number of flux measurements, and improved knowledge of emission factors and area distribution (activity). Based on recent global grid maps and updated evaluations of mud volcano and microseepage emissions, the global geo-CH4 source is now (bottom-up) estimated to be 45 (27–63) Tg yr–1, i.e., ~8% of total CH4 sources. Top-down verifications, based on independent approaches (including ethane and isotopic observations) from different authors, are consistent with the range of the bottom-up estimate. However, a recent top-down study, based on radiocarbon analyses in polar ice cores, suggests that geological, fossil (14C-free) CH4 emissions about 11,600 years ago were much lower (<15 Tg yr–1, 95% CI) and that this source strength could also be valid today. Here, we show that (i) this geo-CH4 downward revision implies a fossil fuel industry CH4 upward revision of at least 24–35%. (ii) The 95% CI estimates of the recent radiocarbon analysis do not overlap with those of 5 out of 6 other bottom-up and top-down studies (no overlap for the 90% CI estimates). (iii) The contrasting lines of evidence require further discussion, and research opportunities exist to help explain this gap.

INSTRUMENTAL MONITORING SYSTEM OF THE KAZBEK VOLCANIC CENTER DEVELOPMENT

Создана система инструментального мониторинга вулканических проявлений в районе Казбекского вулканического центра, включающая 4 сейсмические станции Геофизического института – филиала ВНЦ РАН на Кармадонском параметрическом полигоне и 2 станции сейсмологической службы Грузии. Обмен инструментальными данными позволит выявить целый ряд важных характеристик вулкана Казбек и значительно повысит безопасность жизнедеятельности за счет адекватной оценки риска и прогноза вулканической деятельности Is created the of the instrumental monitoring system volcanic manifestations in the region of Kazbek volcanic center, which includes 4 seismic stations of the geophysical institute of VSC RAS on the Karmadon parametric polygon and 2 stations of the Georgia seismological service. The instrument data exchange will make it possible to reveal a whole series of the important characteristics of volcano Kazbek and will considerably increase safety of vital activity due to the adequate evaluation of volcanic activity risk and forecast

Observations tectoniques dans le Pacifique (Hawaii, Tahiti, Nouvelles-Hebrides)

The Pacific islands of the Hawaii, Society, and New Hebrides groups are characterized by curvilinear faults resulting from peripheral subsidence slippage of portions of the islands toward the ocean deeps. The curvilinear faults are the sites of volcanic manifestations, particularly at junctions with other faults. Faults of the Hawaiian islands (Kilauea, Mauna Loa, and Mauna Kea volcanoes) and Maui (Haleakala) are concave to the southeast. The great curved fault of Oahu and Molokai is concave to the north. Faults in the islands of Moorea and Tahiti of the Society group are concave northward. Faults in the New Hebrides, on the contrary, are concave to the southwest, as are those in the Solomon and New Britain islands. Alpine structure in embryonic form thus is prolonged from the Himalayas and East Indies to the New Hebrides.