Accumulative landforms in valleys with gas-hydrothermal manifestations of the Kuril-Kamchatka region

Within the watercourse valleys of geothermal zones, where manifestations of gas-hydrothermal activity are noted, the processes of relief formation are accompanied by chemical and thermal effects. Thermal waters contribute to the formation of specific accumulative landforms both directly in the channel and in the bottom and on the sides of river valleys. Similar phenomena have been studied in river valleys draining the slopes of the Mendeleev volcano (Kunashir Island), Baransky volcano (Iturup Island), Mutnovsky volcano and Uzon-Geyzernaya caldera (Kamchatka). The typification of accumulative relief forms is carried out, the influence of gas-hydrothermal manifestations on fluvial and slope processes is determined.

Addition to the lichen flora of Iturup Island (Sakhalin Region, Russian Far East)

As a result of expeditionary investigations on Iturup Island (southern group of islands of the Kuril archipelago), 61 species of lichens were identified as new to the island, including Porpidia contraponenda and Xylographa rubescens – new to the Russian Far East, and Amandinea coniops and Arthonia dispuncta – new to the South of the Russian Far East. Six species are new to the Sakhalin Region. The difference in species composition of the Sea of Okhotsk coast and the Pacific coast of Iturup Island is briefly discussed.

Пирит в осадках озер Курильских островов

Holocene sediments of the Kuril Archipelago lakes (Pernatoye, Paramushir Island; Tokatan, Urup Island; Maloye and Kasatka, Iturup Island) were studied. The sediments consist of freshwater lake, lagoon, and marine facies. Pyrite is most often found in sediments of lagoon and marine facies, being their indicator. It is found as separate spheroids and clusters of framboidal structure. Pyrite aggregates fill up diatom valves. Valves were filled with pyrite gradually.

VOLCANISM OF THE EARLY FORMATION STAGE OF ITURUP ISLAND (GREAT KURILE CHAIN)

The article presents new petrogeochemical data on the Middle Miocene-Pliocene volcanic rocks from central part of Iturup Island (Great Kurile Chain). It is shown that volcanism of the Middle Miocene-Early Pliocene age in the central part of the Iturup Island took place in a suprasubduction setting. The distribution of high field strength elements (HFSE) and their ratio in the basaltoids indicate their formation upon partial melting of the depleted upper mantle, while the enrichment of rocks with large ionic lithophilic elements (LILE) indicates both a fluid mantle additive introduced into the melts during the evolution of primary magma and the participation of a low-temperature suprasubduction fluid. The established differences in the composition of the basaltoids of the frontal and rear zones due to the limited number of analyzed samples are considered preliminary. Thus, basaltoids in the rear zone are distinguished by higher concentrations of Th, Pb, HFSE (Nb, Zr, Y, Hf), relative enrichment in LREE, pronounced negative Zr and Hf anomalies, and positive Eu.