Volcanism in the Vitim volcanic field dates back to the Miocene and covers an area of about 4,500 km2 east of the northern part of Lake Baikal. The most voluminous activity took place from the Miocene to Pleistocene, but a second phase occurred during the Pleistocene and Holocene. The latest dated eruption was at about 810,000 years ago. Most of the volcanic centers are located in the NW part of the field (Johnson et al., 2005). Mantle xenoliths are found in several locations.