Partial melting of continental crust is generally considered to produce granitic rocks that have high radiogenic heat production rates when compared to their inferred sources and average continental crust. If this idea is correct, then granulite-facies rocks, which are the sources for crustally derived melt, and comprise the residual material left behind after melt loss, should have depleted heat production rates with respect to crustally derived granites. However, K–U–Th measurements from metapelitic compositions in five metamorphic terranes show that crustal heat production rates do not change significantly between subsolidus and formerly suprasolidus domains that have undergone fluid-absent partial melting and experienced significant (>20 vol%) melt loss. In some cases, crustal heat production rates increase in the residual granulite-facies rocks. This suggests fluid-absent partial melting does not deplete concentrations of heat-producing elements in residual metapelitic-derived granulite-facies rocks. Consequently, basement terranes may retain elevated concentrations of heat-producing elements and therefore be more susceptible to thermo-mechanical reactivation than typically expected.
Conservation of deep crustal heat production
Kiara L. Alessio
David E. Kelsey
Megan A. Williams
Laura J. Morrissey
Kiara L. Alessio, Martin Hand, David E. Kelsey, Megan A. Williams, Laura J. Morrissey, Karin Barovich; Conservation of deep crustal heat production. Geology doi: https://doi.org/10.1130/G39970.1
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