The origin of the Baikal rift zone is under debate between active and passive rifting hypotheses owning to the enigmatic deep structure beneath the region. Revealing the formation mechanism of the Baikal rift zone may help to elucidate the process of continental rifting. Applying P-wave teleseismic tomography to an improved data set, we discover low-velocity anomalies under the southwestern flank of the Baikal rift zone, which are interpreted as hot mantle upwellings from under the Siberian craton, indicating hot materials transferring from beneath the craton to beneath the rift. Our images also reveal low-velocity anomalies under the Hangai Dome, probably suggesting the process of delamination, another consequent effect connected to the Siberian upwellings. We propose that the mantle upwellings beneath the Baikal rift zone and surrounding areas play a vital role in the formation of deep structures and geological settings in this area.
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