A GIS-Based Geological Model for Assessing the Reserves of Phosphate in the Tozeur-Nefta Field, Southern Tunisia

摘要

The Gafsa phosphate basin is the most significant mining region in Tunisia with more than 8 million tons of natural phosphate extracted annually. Both the economic and industrial developments of Tunisia rely heavily on Phosphate deposit and this holds true as long as appropriate estimation of the reserves is undertaken. The aim of this study is to geostatistically explore the phosphate spatial distribution and geological reserve in the Tozeur-Nafta area (part of Gafsa phosphate basin) in Southwestern of Tunisia through sixty boreholes that had been randomly drilled. Optimal unbiased geostatistical tools of ArcGIS-Geostatistical analysts have been used to investigate the quantification of spatial arrangement through outlining the most optimum variogram model. The phosphate-thickness kriged map has shown a spatial distribution of phosphate in the southern of Tunisia. The variants of phosphate thickness in the kriged map reveal there is a rise of phosphate deposits towards the east. Two East-West and North-South correlations were applied using RockWorks16 software which provides visual correlation for phosphate thickness distribution throughout the Tozeur-Nafta region. The East-West correlation confirms that phosphate layer thickness increased towards the East direction, the North-South correlation shows that phosphate thickness in the northeastern limb of the Tozeur-Nafta anticline is more pronounced than in the southeastern limb. Phosphate reserves were estimated using the Ordinary Kriging Method (OKM) at 325.432661 Million tons. The results of this research indicate that the area under study shows much promise as a prospective target for investment in the local raw materials.