heat production - heat flow relations (2)

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RGB airborne radiometric image of the Pilbara - with K concentration on the red colour channel, Th on the green colour channel and U on the blue colour channel.
Light colours are high heat producing granitic rocks, dark colours are low heat production basaltic rocks.
The HPE's are lithophile and strongly fractionated by crust froming processes, explaining the relative enrichment of the upper crust in the HPEs.