1. Geothermics of the Pannonian basin A talk in the frame of the Tibor Mendöl Workshop Lecturer: László Lenkey

2. Fundamentals of geothermics Geothermal gradient = grad T =  T ~  T z = dT/dz ~ ΔT/Δz Heatflow density (heat flow), q=-  T ~ q z = - dT/dz~ - ΔT/Δz, where is the thermal conductivity of rocks Heat transport equation:

5. Thermal lithosphere Herein et al., 2008 Ra=10e6Ra=10e7 2D spherical shell models of thermal convection in the mantle

6. Thermal lithosphere Herein et al., 2008

7. Thermal lithosphere Geotherms in the mantle Schubert et al., 2001

8. Definition of the lithosphere Lithosphere= (Thermal Boundary Layer, TBL)

9. Thickness of the lithosphere in Europe from Artemieva et al. 2006

10. Thickness of the lithosphere in Europe from Artemieva et al. 2006

11. Heatflow in Europe Pollack et al. 1993Artemieva 2003 Thickness of the thermal lithosphere

12. Geothermal conditions in Hungary Geothermal Database of Hungary (Dövényi, 1994)  4477 wells  deeper than 200 m  temperature higher then 30°C  all wells before 1993 12 000 temperature measurements Automatic correction of temperatures Lithology of the well Thermal conductivity data and trends

13. Geothermal database

14. Interpolation, heatflow Temperature corrections –Bottom hole temperature –Wells test –Outflowing water T Calculation of heatflow (condition: constant heatflow) Interpolation of T temperature [°C] depth [m] Thermal conductivity [W/mK] MAKO -2 Measured T Corrected temperature Thermal conductivity Interpolated temperature lithology For 1 layer:

15. Number of temperature measurements in wells EOV X EOV Y vagy több

16. (Horváth et al. 2005: Geodynamic atlas of the Pannonian basin) Heat flow in the Pannonian basin and surrounding areas

17. Processes influencing heatflow –Volcanic activity (e.g. Hargita) –Groundwater flow (e.g. Transdanubian Central Range) –Sedimentation/erosion (e.g. Makó trough) –Variation of thermal conductivity in 2D/3D (topography of the basement of the sediments e.g. Makó trough, Transylvanian basin) –Tectonics

18. Power of thermal springs at the feet of the Transdanubian Central Range

19. (Horváth et al. 2005: A Pannon-medence geodinamikai atlasza) Heat flow in the Pannonian basin and surrounding areas

20. Groundwater, helium and heat transport modell along a section in the Great Hungarian Plain Cserepes and Lenkey, 1999

21. Thickness of Neogene and Quarternary sediments

22. Sedimentation - model A thick and cold sediment layer is deposited at the surface Parameters of the model: –Thickness of the layer –Time of sedimentation –Time passed since deposition Z T T T0T0 T0T0

23. Infill of the Pannonian basin

24. Heatflow deficit due to sedimentation

25. Heatflow corrected for sedimentation

26. Transylvanian basin: variation of heat flow due to variation of the thermal conductivity of rocks

27. Thermal model of lithospheric extension

28. (Horváth et al. 2005: Geodynamic atlas of the Pannonian basin Thickness of the lithosphere in the Pannonian basin

29. Subsidence history Subsidence history off shore eastern cost of North America

30. Subsidence history

33. Summary Heat flow is an important geodynamic parameter Large scale variation in heat flow are caused by tectonic processes Small scale variations are due to groundwater flow, volcanism, variations in thermal condcutivity and heat production High heat flow in the Pannonian basin is a result of lithospheric extension occurred 20-15 Ma The extension of the lithosphere was not uniform: the mantle part was more thinned than the crust