Heterogeneous Crystalline Crust Controls the Shallow Thermal Field – A Case Study of Hessen (Germany)

We present a seismic- and 3D-gravity-constrained lithospheric-scale 3D structural model of Hessen that differentiates 7 sedimentary units, 5 Variscan upper crustal bodies, the lower crystalline crust and the lithospheric mantle. To predict the present- day subsurface temperatures, we solve the steady-state conductive heat equation by using a 3D FE method and assigning lithology-dependent thermal properties. We show that the thermal field is mainly controlled by the varying radiogenic heat production in the crystalline crust, which results in a colder NW and a warmer SE domain. Locally, this regional trend is superimposed by thermal blanketing of low-conductive sediments leading to higher temperatures.