Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/100086
Type: Thesis
Title: Comparison of geophysical techniques to determine depth to bedrock in complex weathered environments of the Mount Crawford region, South Australia
Author: Fotheringham, T. J.
Issue Date: 2013
School/Discipline: School of Physical Sciences
Abstract: Geophysical techniques have the ability to characterise the subsurface and define the depth to bedrock. The non-destructive nature and relatively cheap costs of geophysical surveying compared to drilling make it an attractive tool for subsurface analysis. Many studies have utilized geophysics to interpret soil features such as clay content, water content, salinity, textural properties and bulk density. Further work has been done to map the regolith-bedrock boundary. Previous work has been conducted in the Mount Crawford region using remote sensing based techniques to determine depth to bedrock. Comparisons between the effectiveness of different geophysical techniques at determining depth to bedrock have not previously been undertaken in similar environments. Fieldwork was undertaken along three transects chosen to represent different geological environments. Three geophysical apparatus were compared: Electrical Resistivity (ER), Frequency Domain EM (FDEM) and Ground Penetrating Radar (GPR). A simultaneous soil sampling program was conducted to provide ground truthing. The work in this study reveals the strengths and weakness of the three geophysical techniques at determining depth to bedrock in complex weathered environments of the Mount Crawford region, South Australia. The study reveals differences in the responses of the three geophysical techniques at each of the transects. The GPR was found to be largely unsuitable due to rapid attenuation of the signal. Resistivity and FDEM appeared to show similar variations in the models generated, with differences in the resolution and depth of investigation relating to intrinsic differences between the two systems. Qualitative analysis of the data suggests resistivity provides the strongest correlations with drill refusal depths. The FDEM appeared to display similar trends to the resistivity data and the system offers faster data acquisition, however the inverted model displays lower resolution. The data suggests that bedrock along the surveyed transects is highly weathered and relatively conductive compared to overlying regolith.
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2013
Where: Mount Lofty Ranges, South Australia
Keywords: Honours; Geology; bedrock; resistivity; DualEM; Ground Penetrating Radar; Mount Crawford; geophysics
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
Appears in Collections:School of Physical Sciences

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