The thermal regime of the crystalline continental crust: Implications from the KTB

Abstract

Abstract. An extensive geothermal research program within the German Continental Deep Drilling Program (KTB) covered an almost complete spectrum of experimental and theoretical aspects. The main results and conclusions are as follows: (1) Equilibrium temperature is 118.6øC at 4000 m in the KTB pilot borehole (KTB-VB) and will be around 260øC at 9100 m in the KTB main borehole (KTB-HB). Time required for thermal equilibration of the KTB-HB to within 1% of the initial perturbation will be about 13-16 years. for large rock volumes, but simple numerical models indicate that the associated temperature regimes are imcompatible with KTB borehole data. (6) Heat production rate shows no systematic variation with depth and is related to lithology at the KTB as in other deep boreholes in crystalline rock. Numerical models, using heat production rate derived from seismic velocities, yield temperatures compatible with KTB borehole data.

Predicting heat flow in the 2001 Bhuj earthquake (<i>M</i><sub>w</sub>=7.7) region of Kachchh (Western India), using an inverse recurrence method

“…This may be especially true for mid to higher latitudes where warming of the ground surface since the Pleistocene has resulted in a transient reduction in surface temperature gradient which often persists to a depth of up to about 2 km. Such signal is also clearly visible in KTB borehole (Germany) (Clauser et al, 1997), which is one of the deepest drilled ever. In this borehole, measured present day heat flow is systematically too low, down to ∼1500 m depth (Clauser et al, 1997).…”

“…Such signal is also clearly visible in KTB borehole (Germany) (Clauser et al, 1997), which is one of the deepest drilled ever. In this borehole, measured present day heat flow is systematically too low, down to ∼1500 m depth (Clauser et al, 1997). It is common knowledge that in shallow boreholes, more recent climatic perturbations upto the Holocene period are important (Beck, 1977).…”

“…Further, observed surface heat flow has often been correlated with the thickness of the lithosphere Crough and Thompson, 1976;Negi et. al, 1987).…”

Thermal regime and heat transfer during the evolution of continental collision structures

“…The heat production in the 5 km main hole in the Chinese continental scientific drilling program shows increase from ∼ 0.5 to 1.7 W/m 3 [He et al, 2008]. At KTB, heat generation is the same at the depths 8-9 km and 1-2 km [Clauser et al, 1997] (Figure 2). …”

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

“…Calculating bulk thermal conductivities inversely from local heat flow density and log-derived interval temperature gradients (Blackwell and Steele 1989;Fuchs and Förster 2010) Another potential explanation would be an inherited paleoclimatic effect, induced by lower surface temperatures during the Pleistocene ice ages and responsible for reduced thermal gradients in the shallow subsurface at present-day (e.g. Clauser et al 1997;Norden et al 2008;Šafanda and Rajver 2001;Šafanda et al 2004). A related non-equilibrium of the measured temperature logs, i.e.…”