Trend surface analysis of Th,U, and K,and heat production in three related granitic plutons,Farsund area,south Norway

The radioelement concentrations and their distributions in the light (biotite hornblende) Farsundite and dark (charnockitic) Farsundite suggests that they are distinct plutons and not comagmatic. The trend surfaces of radioelement concentrations, coupled with available gravity data indicates that the light Farsundite has a closer relationship to the Holum granite than to the dark Farsundite. Average radioelement concentrations for the three plutons suggests they are all part of a low heat production province which may be related to the low radioelement contents in the rocks of the Egersund area to the west.