Triassic Magmatism of the Talmi Volcanic Structure (Southwestern Primorye): Mantle and Crustal Sources and Evolution of Melts

New mineralogical–petrographical and isotope-geochemical data, as well as numerical simulation results, suggest that high-magnesian basalts and basaltic andesites of the eastern block of the Talmi volcanic structure formed as a result of crystallization differentiation during the rapid ascent of mantle magmas to a depth of ∼7.5 km, under conditions of relatively low oxygen fugacity and water content. We consider acid volcanics (SiO2 ∼76–78 wt %) of the central block as crustal melts, the mixing of which with mantle melts in shallow peripheral chambers leads to the appearance of andesites with numerous mineralogical and geochemical signs of hybridism. The geodynamic position of Triassic volcanism is governed by a transtensional regime under conditions of regionally manifested submeridional compression.