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Finite-element analysis of shallow temperature anomaliesNormal access

Author: J. Geertsma
Journal name: Geophysical Prospecting
Issue: Vol 19, No 4, December 1971 pp. 662 - 681
DOI: 10.1111/j.1365-2478.1971.tb00909.x
Organisations: Wiley
Language: English
Info: Article, PDF ( 1.24Mb )

Summary:
Finite-element analysis has been used in calculating shallow temperature anomalies due to both the presence of salt domes and near-surface faults. The results of the numerical analysis are in good agreement with field observations reported earlier by Poley and van Steveninck. The calculations show how surface emissivity must be responsible for the pronounced temperature anomalies above salt domes.

Faulting is a mechanism that disorders the layering sequence of sedimentary deposits. If the disordered sedimentary layers show notable differences in heat conductivity, the layers are thick enough and the displacements along the fault plane large enough, temperature anomalies close to the free surface may be apparent because of the surface-emissivity mechanism.

In order to explain certain characteristic temperature anomalies where a fault reaches or approaches the free surface, an additional mechanism has to be assumed; namely a distortion of texture, and consequently a change in the heat conductivity of the rock material surrounding the fault plane. The consequences of both a reduced and an increased heat conductivity of the surroundings of a near-surface fault have been calculated, and they show remarkable agreement with temperature anomalies observed in various parts of the world.


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