Hot Spot and Structure of the Western Baikal Rift System

Space-time distribution of volcanism in the Belaya dome uplift, Upper-Oka rift segment, and Khubsugul-Belaya accommodation zone are considered in connection with hot spot evolution at the western Baikal rift system. The accommodation zone has the north-south trend, spatially corresponding to the central part of the dome uplift and separating the Tunka rift segment from the Upper-Oka and Khubsugul rift segments. Uplifting of the Belaya arch took place in the Early Miocene and is supposed to be the result of the mantle hot plume ascent. Rifting was accompanied by lateral under-lithosphere spreading of hot mantle material. Plume-related lavas in the Oka volcanic field were characterized by olivine tholeiite and alkali olivine basalt composition, relatively high Sr and low Ba concentration. During rifting basanite melts were produced by interactions of asthenosphere magmas with high-Mg peridotites of lithosphere mantle.