Heat flow and lithospheric thermal regime in the Northeast German Basin

Deep 3D thermal modelling for the city of Berlin (Germany)

“…In addition, a unit dominated by rock salt (the Upper Permian Zechstein salt), which forms numerous domes and diapirs in the region and is characterised by higher thermal conductivities than the overlying sedimentary sequences, induces significant small-scale thermal anomalies (e.g. Balling et al 2013 -this issue;Bayer et al 1997;Cacace et al 2010;Cherubini et al 2013 -this issue;Hurtig and Rockel 1992;Noack et al 2010;Norden et al 2008). Beside thermal conduction, also heat transfer coupled to flowing groundwater has been identified as an important controlling factor for subsurface temperatures in the NEGB (Cacace et al 2010;Kaiser et al 2011;Noack et al 2013 -this issue).…”

“…For instance, radiogenic-heat-production values have been determined for the main geological units of the sediments and crust based on laboratory measurements, well log and chemical analyses (Norden and Förster 2006;Norden et al 2008Norden et al , 2012. A similarly comprehensive database of thermal conductivities measured on drill core samples is available (Fuchs and Förster 2010;Norden and Förster 2006;Norden et al 2008).…”

“…A similarly comprehensive database of thermal conductivities measured on drill core samples is available (Fuchs and Förster 2010;Norden and Förster 2006;Norden et al 2008). However, we additionally use temperature logs available for the boreholes Velten and Wartenberg to derive rock thermal conductivity from observed temperature gradients.…”

“…For the present study, the interval temperature gradients are computed from high-precision temperature measurements (logged under thermal equilibrium conditions; LIAG 2009). The interval heat flow values, in turn, were computed based on an average surface heat-flow density of 77 mW/m² that represents a mean value estimated for the NEGB where values range between 68 and 91 mW/m² (Norden et al 2008). …”

“…Since direct information on the thermal properties of rocks in the subsurface of Berlin is still sparse, e.g. core samples on which laboratory measurements could be performed, we partly revert to measured data from the same stratigraphic units in other parts of the NEGB (Norden and Förster 2006;Norden et al 2008).…”