Electrical and seismic tomography used to image the structure of a tailings pond at the abandoned Kettara mine, Morocco

Date

2012-03

Journal Title

Journal ISSN

Volume Title

Publisher

Springer

Abstract

The Kettara site (Morocco) is an abandoned pyrrhotite ore mine in a semi-arid environment. The site contains more than 3 million tons of mine waste that were deposited on the surface without concern for environmental consequences. Tailings were stockpiled in a pond, in a dyke, and in piles over an area of approximately 16 ha and have generated acid mine drainage (AMD) for more than 29 years. Geophysical methods have been used at the Kettara mine site to determine the nature of the geological substrate of the tailings pond, the internal structure of the mine wastes, and to investigate the pollution zones associated with sulphide waste dumps. Electrical resistivity tomography (ERT) and seismic refraction data were acquired, processed, and interpreted; the results from ERT and seismic refraction were complementary. A topographical survey of the tailings disposal area was also undertaken to estimate the volume of wastes and quantify the AMD process. Two-dimensional inverse models were used to investigate the geophysical data and indicated alteration zones at depth. It was determined that the material could be classified into three categories: tailings, with low resistivity (5–15 Ω m) and low velocity (500–1,800 m/s); altered, black shales, with intermediate resistivity (20–60 Ω m) and velocity (2,000–3,500 m/s), and; materials with high resistivity and velocity (>60 Ω m and >4,000 m/s, respectively), including unaltered shales associated with quartzite seams. The low-resistivity zone generates AMD, which migrates downward through fractures and micro-fractures. The substrate is composed of broken and altered shale, which facilitates AMD infiltration.

Description

Keywords

ACID MINE DRAINAGE, MINE WASTE, ELECTRICAL RESISTIVITY TOMOGRAPHY, KETTARA MINE SITE, SEISMIC REFRACTION TOMOGRAPHY, ENVIRONMENTAL DAMAGE, TOPOGRAPHY

Citation

Meriem Lghoul, Teresa Teixidó, José Antonio Peña, Rachid Hakkou, Azzouz Kchikach, Roger Guérin, et al. (2012). Electrical and Seismic Tomography Used to Image the Structure of a Tailings Pond at the Abandoned Kettara Mine, Morocco. Mine Water and the Environment, 31(1), 53-61.doi:10.1007/s10230-012-0172-x

DOI