Journal of Earth Sciences and Geotechnical Engineering

Characterizing aggregate deposits using electrical resistivity method: case history of sand search in the Niger Delta, Nigeria

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• Abstract 

  Natural aggregates (e.g sand and gravel) are indispensible natural resource for any society. This is because sand and gravel deposits are good groundwater and hydrocarbon reservoirs, sources of obtaining economic placer deposits such as gold, tin, diamond etc, and are useful construction aggregates for civil engineering projects. It will be difficult to maintain our current quality of life without sand and gravel.  In order to obtain robust subsurface models to accurately delineate the geometry of sand and gravel deposit, we integrated geoelectric sounding and 2D resistivity imaging in an attempt to source for natural aggregates to reclaim swampy land in two oil bearing communities in the Niger Delta. The electrical resistivity investigations were carried out in seven locations. Due to the problem of equivalence associated with the interpretation of geoelectric sounding data, borehole data was used to constrain the interpretation. The total volume of dredgeable sand was calculated by using a simple volume arithmetic in which the length and width of the survey area was multiplied by the average sand thickness. The results show that four of the seven sites, whose bulk resistivity did not exceed 900 Om, were found to have no coarse material when drilled for verification. Significant accumulations of about 50,000 m³ of high resistivity deposits were found in each of the remaining three sites and were recommended for dredging. Application of geophysics to sand and gravel prospecting enhances considerable economic saving for the aggregate industry and also an environmental saving for society.

  Keywords: Sand and gravel, 2D resistivity imaging, Geoelectric sounding, Swampy land, Niger Delta