Up until now heat flow through the bottom of Lake Baikal has been determine
d in more than 700 sites. Mean measured flux is 73.5 +/- 24 mW/m(2); correc
ted for topography and sedimentation it is 77.8 +/- 24 mW/m(2). Heat flow v
alues vary greatly in a range from 0 to 20 000 mW/m(2). The zero values wer
e obtained in localities of recent landslides, while the extreme highs are
attributed to sites of hydrothermal discharge. In the northern Baikal, narr
ow positive heat flow anomalies are associated with near-shore faults exten
ding along bottom foothills on both sides of the basin. An intense heat flo
w anomaly, about 8 km wide, stretches along the southeastern side of Centra
l Baikal. Its position coincides with a fault detected by seismic multichan
nel reflection.
The most prominent positive anomaly is the one over 30 km wide, found in So
uth Baikal. An attempt was made earlier to explain this anomaly by injectio
n of mantle material into the upper crust. Estimations performed with regar
d to hydrothermal outflow of heat show that such an intrusion, even if it w
ere 10 to 12 km wide, would be able to sustain the anomaly in South Baikal
for less than 1 My. If the anomaly had existed for a longer time it must ha
ve been fed by renewable sources of heat. Ground waters may provide such a
source. They penetrate along faults to depths of 3 to 6 km and deeper benea
th the rift shoulders where they heat-up in the regional thermal field, the
n move towards the Baikal basin and ascend through the faulted bottom of La
ke Baikal already as thermal waters. Modelling shows that such redistributi
on of deep heat by moving ground waters is also responsible for low heat fl
ows of less than 40 mW/m(2)observed in shallow boreholes in the rift should
ers.