Geothermal data on six kimberlite provinces of ancient platforms in Siberia
, Africa, North America, and South America are considered. The intensity of
heat flow there varies from 10-18 to 62-100 mW/m(2), averaging 46-54 mW/m(
2). These average values are in concordance with conductive geotherms obtai
ned by thermobarometry of mineral associations from deep-seated xenoliths f
rom kimberlite pipes. The only exclusion is the Yakutian kimberlite provinc
e In the east of the Siberran Platform, where the intensity of measured hea
t flows (20-30 mW/m(2)) is considerably lower than that calculated for the
time of kimberlite formation (35-40 mW/m(2)). This anomaly may be related n
ot to the climate cooling but to a decrease in the intensity of radiogenic
heat generation in the Earth's crust and shielding of mantle heat now. This
is suggested from the occurrence of kimberlite fields within the protrusio
ns of the lower crust with minimum contents of radioactive elements in its
rocks.