Heat transfer processes in the upper crust: influence of structure, fluid flow, and palaeoclimate
Numerical models constrained by geological and geophysical data form the basis of understanding the thermal regime of the Earth's crust. This dissertation focuses on modelling heat transport in the upper crust, studying the relative contributions of different processes to the specific heat flow...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Publikationsserver der RWTH Aachen University
2007
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| Online Access: | https://publications.rwth-aachen.de/record/62428 https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123997%22 |
| Summary: | Numerical models constrained by geological and geophysical data form the basis of understanding the thermal regime of the Earth's crust. This dissertation focuses on modelling heat transport in the upper crust, studying the relative contributions of different processes to the specific heat flow distribution. Its vertical variation is a well known fact, caused by different processes such as changes in surface temperature, fluid flow, and heterogeneity. In particular, the first one can provide valuable information. Since the subsurface temperatures are directly related to past temperatures, their inversion into ground surface temperature histories are the only method available in palaeoclimatology to construct palaeotemperatures without using indirect proxy methods. Furthermore, a general better understanding of the processes affecting the thermal regime of the upper crust is needed for better downward continuation of thermal data, which is important for considerations about the thermal evolution of the lithosphere. A large geothermal data set from the Kola peninsula is processed and described in detail in order to prepare it for a numerical case study simulating heat transport processes in the Kola super-deep hole area. The data set includes 3400 measurements of thermal conductivity on 1375 samples from 21 boreholes with a depth up to 1.6 km and 36 temperature logs. The modelling involves 3-D forward simulation of both conductive and advective heat and mass transfer, and 1-dimensional inverse modelling for the palaeoclimatic ground temperature changes in the study area. Steady-state and transient 3-D models as well as the inverse modelling allow to estimate and quantify systematically the influence of fluid flow, spatial heterogeneity of thermal properties of rock, and palaeoclimate on the subsurface temperature field. Being aware that the information on permeability is sparse, the modelling results suggest that advection has a major influence on the vertical specific heat flow distribution. This is confirmed by ... |
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