Identification of Possible Weakness Zones in Limestone Bedrock by Resistivity and Induced Polarization
Författare
Summary, in English
In connection to an environmental investigation of a former industrial site, the cretaceous sandy limestone bedrock in the surrounding area were mapped with resistivity and time domain induced polarization (DCIP). The aim of the DCIP survey was to delineate geological units and possible preferential pathways of DNAPL contaminated groundwater. Although IP anomalies corresponding to fractured crystalline bedrock have been observed previously and are commonly interpreted as results of clay weathering, there are not many studies of the IP behavior of limestone in previous research. In contrast to silicates, the weathering of calcite minerals in pure limestone results only in dissolution, without any weathering products in form of minerals. In this study, varying resistivity values and large IP anomalies were found in the sandy limestone bedrock, which are probable indications of weakness zones. The observed strong IP anomalies may be caused by calcite dissolution and precipitation processes or by clay mineral precipitation from chemical weathering of the silica grains contained in the sandy limestone. Another possibility may be sporadic presence of glauconitic sand in the limestone. More research is needed to confirm the sources of the observed anomalies.
Avdelning/ar
Publiceringsår
2015
Språk
Engelska
Publikation/Tidskrift/Serie
Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics
Dokumenttyp
Konferensbidrag
Förlag
European Association of Geoscientists & Engineers
Ämne
- Geophysics
- Geology
Conference name
Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics
Conference date
2015-09-06 - 2015-09-10
Conference place
Torino, Italy
Status
Published
Projekt
- Geoelectrical Imaging for Site Investigation for Urban Underground Infrastructure