We consider the structure, composition, and age of Early Paleozoic intrusive associations of the Bumbat-Hairhan area located in the central part of the island-arc system of the Lake Zone, western Mongolia. There are large polychronous plutons (Bumbat-Hairhan and Gundguzin) and small intrusions in this area. We have established that they are composed of granitoid and gabbroid associations of different lithology, ages, and geodynamic nature. The results of U-Pb dating show that granitoid and basic magmatism took place within 551–465 Ma. Two main stages of intrusive magmatism are recognized, which reflect two stages of the geodynamic evolution of the region: island-arc (551–524 Ma) and accretion–collision (511–465 Ma). At all stages, predominant rocks in the region were diorite–tonalite–plagiogranite and plagiogranite associations of calc-alkaline series.

Selenium compounds are relatively rare as minerals; there are presently only 118 known mineral species. This work is intended to codify and systematize the data of mineral systems and the thermodynamics of selenium minerals, which are unstable (selenides) or formed in near-surface environments (selenites), where the behavior of selenium is controlled by variations of the redox potential and the acidity of solutions at low temperatures and pressures. These parameters determine the migration of selenium and its precipitation as various solid phases. All selenium minerals are divided into four groups-native selenium, oxide, selenides, and oxysalts-anhydrous selenites (I) and hydrous selenites and selenates (II). Within each of the groups, minerals are codified according to the minimum number of independent elements necessary to define the composition of the mineral system. Eh-pH diagrams were calculated and plotted using the Geochemist's Workbench (GMB 9.0) software package. The Eh-pH diagrams of the Me-Se-H 2 O systems (where Me = Co, Ni, Fe, Cu, Pb, Zn, Cd, Hg, Ag, Bi, As, Sb, Al and Ca) were plotted for the average contents of these elements in acidic waters in the oxidation zones of sulfide deposits. The possibility of the formation of Zn, Cd, Ag and Hg selenites under natural oxidation conditions in near surface environments is discussed.

A Neanderthal Refugium in the Eastern AdriaticOn the basis of mineralogical analysis of the tephra layer in the Bioče rock shelter in Montenegro, we revise the cultural and population changes in the eastern Adriatic at the Middle to Upper Paleolithic transition. The disappearance of Neanderthals from that region was traditionally attributed to the Campanian Ignimbrite eruption ~40 ka BP. Comprehensive studies at Bioče by the Russian-Montenegrin expedition in 2010-2015 have resulted in a hypothesis that a Neanderthal refugium existed in the Balkans. We list the lithological and stratigraphic characteristics of the Pleistocene sequence of the site and describe four main strata. Petrographic and x-ray phase analyses and scanning electron microscopy suggest that minerals from samples of ground from horizon 1.3 are of volcanic origin. The comparison of tephra from that horizon with those from local sequences in terms of composition, shape, and size of particles reveals similarity with the Y-5 tephra from the main phase of the Campanian eruption, dating to 39.30-39.85 ka BP. In the habitation sequence of Bioče, the tephra layer is inside lithological stratum 1. Artifacts from that layer and from the overlying and underlying ones, judging by technological and typological criteria, belong to one and the same lithic industry-the micro-Mousterian facies of the local Middle Paleolithic. New fi ndings imply that the Campanian Ignimbrite eruption did not cause the disappearance of the culture associated with Neanderthals in the eastern Adriatic.

—The mineral composition, petrography, and petrochemistry of middle Cambrian diopside porphyry basalts of the Ust’-Sema Formation in Gorny Altai are considered in comparison with ankaramites of different geodynamic settings. The basalts of the Ust’-Sema Formation are enriched in phenocrysts of high-Mg clinopyroxene (Mg# ≤ 94) (20 to 40–50 vol.%) with a high content of Cr2O3 (up to 1.11 wt.%), enclosed in the clinopyroxene–plagioclase microlitic groundmass. In addition, there are minor phenocrysts of saussuritized plagioclase (An49–71), olivine replaced by secondary minerals, amphibole with Mg# = 55.7–68.2, and Cr-spinel with Cr# = 36.2–41.7. Inclusions of Cr-spinel in high-Mg clinopyroxene are richer in Cr (Cr# ≤ 72.8). The basalts of the Ust’-Sema Formation are chemically heterogeneous and are subdivided into two main groups: high-Ca (MgO = 7.98–14.77 wt.% and CaO/Al2O3 = 1.0–1.8) and low-Ca (MgO = = 2.84–9.89 wt.% and CaO/Al2O3 = 0.2–0.9). The obtained data on the high-Ca basalts of the Ust’-Sema Formation show that the rocks are similar to the reviewed ankaramites and thus can be assigned to this type of rocks. The low-Ca basalts of the Ust’-Sema Formation might have resulted from the fractionation of ankaramitic melt in intermediate magma chambers. The Gorny Altai ankaramites formed through the melting of the wehrlitized suprasubductional lithospheric mantle during the closure of the Paleoasian Ocean.