Electrical resistivity of saturated and unsaturated sediments in northeastern Canada

This study presents typical values of electrical resistivity for common saturated and unsaturated sediments in Québec in the form of a resistivity chart. The database for this study consists of surface geophysical investigations [i.e., transient electromagnetic (TEM) surveys] together with stratigraphic and hydrogeological data from boreholes drilled among five regions of the Province of Québec in Canada: Mauricie, Abitibi-Témiscamingue, Saguenay-Lac-Saint-Jean, Charlevoix and Haute-Côte-Nord. TEM stations were selected near the sites where boreholes, stratigraphic cross-sections and piezometric surveys were acquired to derive an empirical and local petrophysical relationship and establish a resistivity chart of the sediments. This chart proposes ranges of resistivity applying to fourteen classes of common sediments, seven of which have never been included in previous studies: silty clay, clay with sand/gravel/pebbles, unsaturated clayey silt with sand, saturated and unsaturated silty sand and saturated and unsaturated clayey sand and gravel. A standardization method was developed and used in this study to produce an accurate and representative chart, and to eliminate outliers that might distort the results and reduce their relevance. This method was designed with the aim of mitigating the impact of outliers and ensuring a reliable and consistent dataset. The findings from this study may provide scientists and practitioners with precise electrical resistivity characteristics of typical saturated and unsaturated sediments, enabling a more accurate assessment of groundwater resources.