Heat shielding effects in the Earth’s crust

Knowledge of heat flow and associated variations of temperature with depth is crucial for understanding how the Earth functions. Here, we demonstrate possible heat shielding effects that result from the occurrence of mafic intrusions/layers (granulitic rocks) within a dominantly granitic middle crust and/or ultramafic intrusions/layers (peridotitic rocks) within a dominantly granulitic lower crust; heat shielding is a familiar phenomenon in heat engineering and thermal metamaterials. Simple one-dimensional calculations suggest that heat shielding due to the intercalation of granitic, granulitic and peridotitic rocks will increase Moho temperatures substantially. This study may lead to a rethinking of numerous proposed lower crustal processes.