Study of the chemical composition of clinopyroxene and garnet megacrysts from the Dak Nong sapphire deposit and model calculations have shown that megacrysts originated from the crystallization of alkali basaltoid magma in a deep-seated intermediate chamber at 14–15 kbar, which is close to the Moho depth (50 km) in this part of southeastern Asia. The chamber was a source of heat and CO2 fluids for the generation of crustal syenitic melts producing sapphires and zircons. The formation conditions of sapphires and zircons are significantly different. The presence of jadeite inclusions in placer zircons points to high pressures during their crystallization, which is confirmed by the ubiquitous decrepitation of CO2-rich melt inclusions. Sapphires crystallized from iron-rich syenitic melt in the shallower Earth’s crust horizons with the participation of CO2 and carbonate–H2O–CO2 fluids. The subsequent eruptions of alkali basalts favored the transportation of garnet and pyroxene megacrysts as well as sapphire and zircon xenocrysts to the surface. It is shown that sapphire deposits can be produced only during multistage basaltic volcanism with deep-seated intermediate chambers in the regions with thick continental crust. The widespread megacryst mineral assemblage (clinopyroxene, garnet, sanidine, ilmenite) and the presence of placer zircon megacrysts can be used as indicators for sapphire prospecting.

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We have shown that the occurrences of Permo-Triassic magmatism in northern Vietnam compose the southwestern and southeastern flanks of the Emeishan large igneous province, shifted along the large-amplitude Ailao Shan-Red River shear zone. Based on new geochronological (U-Pb and Ar/Ar) data, two stages of magmatism related to the Emeishan plume have been recognized. At the first, Permian, stage (260 Ma), abundant picritoids of the Song Da and Song Hien zones formed, and at the second, gabbro-syenite and gabbro-monzodiorite associations of the Lo Gam zone, layered peridotite-gabbro massifs of the Nui Chua complex, high-alumina granites of the Phia Bioc complex, and basalt-rhyolite association of the Song Hien zone were produced. The metallogenic specialization of the Permo-Triassic magmatism of northern Vietnam is considered.

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The paper presents new data on geochemistry (major and trace elements, isotopes) and petrology (composition of phenocrysts and mineral thermometry) of basalts from the Early Cambrian Katun’ accretionary complex of the Kuznetsk–Altai island arc (Gorny Altai). We also discuss the geodynamic settings of the formation of basalts based on petrologic, geochemical and isotope data taking into account their relationships with associated sedimentary rocks of oceanic origin and with terrigenous sedimentary rocks of the accretionary complex. The Late Neoproterozoic basalts associated with siliceous sediments are characterized by medium TiO2 and Zr/Nb, flat REE patterns and Nb/Lapm < 1 (MORB-type oceanic floor basalts). The oceanic floor basalts are represented by high- and low-magnesium varieties. The Early Cambrian basalts (Manzherok Formation) were formed in an oceanic island setting (OIB-type). They occur in sections consisting of paleo-oceanic island basalts alternated with siliceous-terrigenous-carbonate sediments of slope facies. The Manzherok basalts are characterized by high crystallization temperatures (1175 °C), and enriched incompatible elements (LREE, Ti, Nb), whose variations suggest a mantle plume source and variable degrees of partial melting in the spinel and garnet stability fields. The low to high-Mg Middle Cambrian basalts of the Ust’-Sema Formation occur as subparallel dikes and lava flows, which cut and overlap the accretionary complex. The basalts are characterized by low TiO2, Nb, LREE, high Zr/Nb and, compared to the OIB-type basalts, lower temperatures of crystallization, 1047 °C and 1138 °C for the low- and high-Mg varieties, respectively. Geochemically, the low-Mg basalts of the Ust’-Sema Formation are close to MORB, and the high-Mg basalts—to island-arc tholeiites. Such a combination of geochemical and geological data suggest that the low-Mg basalts of the Ust’-Sema Formation formed during ridge subduction, and the high-Mg basalts formed in a suprasubduction setting, at the crust-mantle boundary.

Four stages of the thermochemical plume—lithosphere interaction generating a broad mushroom-like head of plume and especially fourth regressive cooling phase have the important role for metallogeny. The analysis of a thermochemical plume model together with recent geological and geochronological data on magmatic ore systems in the Siberian, Tarim, Emeishan, Central European, and some other large igneous provinces (LIPs) enabled the following characteristics of the metallogeny in large igneous provinces to be revealed: (1) the specific combination of mineralization types, which include magmatic Cu-Ni-Pt and Fe-Pt; hydrothermal Ni-Co-As (±Ag, U, Au), Au-As, Ag-Sb, Au-Hg, Sb-Hg and stratiform Cu (copper-bearing sandstones and shales enriched in Co, Ni, Ag, Pt);(2) the areal or spot-like pattern of the location of mineralization types (opposed to the linear-belt localization in subduction and rift settings);(3) the zoned distribution of mineralization types relative to LIPs’ centers, with Cu-Ni-Pt, Fe-Pt and stratiform Cu mineralization localized in a LIP center, and hydrothermal mineralization bound to a LIP periphery;(4) the essential contemporaneity of the formation of each mineralization type in LIPs, and the existence of coeval but spatially separated Cu-Ni-Pt, Ni-Co-As and Au-As deposits;(5) the close linkage between different mineralization types and particular pulses of mafic, alkaline mafic, and felsic magmatism;(6) the unified succession of ore-forming events;(7) the close relationship between the extent of mineralization and LIP igneous volumes, which in turn depend on the plume heat power. The major characteristics of localization of different mineralization types within LIPs, the timing and genetic relationships between mineralization and types of magmatism, as well as specific geological controls on ore formation provide a basis for establishing new geological, magmatic, litological, and geochemical criteria crucial for predicting and targeting new mineralization within LIPs.

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We discuss strike-slip tectonics as the key agent in the formation of the Early Paleozoic (Caledonian) collisional system of the western Baikal region. This tectonic setting implies existence of local syncompressional extension, with the ensuing conditions for mantle drainage and magmatism. Lower-middle crust collisional complexes exposed in the Olkhon area of the western Baikal region provide a record of synmetamorphic subalkaline-mafic magmatism associated with the early synorogenic collapse of the Olkhon collisional system, a part of the Central Asian collisional-accretionary belt.