Jom-Bolok volcanic field is located in the East Sayan Mts. of Siberia (Russia), a portion of the Asian convergent zone. It is located at the boundary of the Riphean Tuva-Mongolia massif, which was probably reactivated because of the interplay between far-field tectonic stress derived from the India-Asia collision zone and extension in the south-western Baikal rift system. The volcanic field comprises a number of hawaiitie lava flows, of various lengths, which flowed down paleorivers. Flows were fed by fissure eruptions and the largest lava flow field was dated as 7,130 ± 140 cal (14)C years BP using a buried organic sample found inside the associated cinder cone. This lava flow field is about 70 km long, similar to 100 km(2) in area, and 7.9 km(3) in volume. The area and volume of this flow field ranks this eruption highly in the global record of fissure-fed effusive eruptions. This lava flow field makes up 97% of the entire Jom-Bolok volcanic field, a fact which raises a puzzling question: why and/or how did a relatively small-volume volcanic field produce such a large-volume individual eruption? A working hypothesis is that a pond of sublithospheric melt accumulated over a relatively pro-longed period. This was then rapidly drained in response of tectonic changes triggered by unloading of ice in the Early Holocene
