Geophysical mapping and mineralisation characterisation of the mesothermal auriferous basement complex in southern Kebbi, NW Nigeria

Figures & data

Figure 1. Geological map of southern Kebbi

Table 1. Radioelement contents of some rock types and minerals (extracted from Dickson and Scott 1997; International Atomic Energy Agency (IAEA) 2003; Dentith and Mudge 2014)

Rock type/mineral	K (%)	Th (ppm)	U (ppm)
Orthoclase Microcline Anorthoclase Biotite Muscovite Glauconite Shale Illite Plagioclase Pyroxene Amphibole Olivine Quartz Zircon Calcite *Granitoid *Gneissic rock	14.05 14.05 3.67 9.02 9.81 5.49 0.1–5.0 5.03 0.1–0.5 0.1–1.2 10–11.4 10–12.6 1.0–5.0 0.7 0.1–6.5 0.3–4.5 12.4–13.8	12.0–15.0 12.0–15.0 4.2–4.5 0.1–1.2 0.1–1.2 0.1–1.2 1.6–13.8 4.6–5.2 0.1–5.0 0.1–40 0.1–0.3 0.1–1.5 1.3–5.0 0.1–35.0 0.4–7.9 0.4–7.8 2.1–13.6	0.2–1.3 0.2–1.3 0.2–1.3 0.8–3.1 0.6–3.1 0.1–3.1 1.0–5.5 1.0–1.5 0.1–3.0 0.1–2.5 0.1–0.5 0.1–4.0 6.0–16.0 0.1–25.0 0.1–2.9 2.3–4.5 1.8–5.5

*Rock types showing average range of radionuclide value.

Figure 2. Total magnetic intensity map

Figure 3. Reduced to equator magnetic map

Figure 4. Residual magnetic (intensity) map

Figure 5. Analytic signal magnetic map

Figure 6. First vertical derivative magnetic map

Figure 7. Structural map derived from magnetic interpretation

Figure 8. Euler solutions map

Figure 9. Potassium concentration map

Figure 10. Thorium concentration map

Figure 11. Uranium concentration map

Figure 12. Potassium-to-thorium ratio map

Figure 13. Ternary map

Figure 14. Radiolithic map

Figure 15. Depth profile of the area

Figure 16. Geophysical classification map

Figure 17. Euler solutions superimposed on ternary image

Dickson BL, Scott K. 1997. Interpretation of aerial gamma-ray surveys adding geochemical factors. AGSO J Aust Geol Geophys. 17(2):187–200.

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International Atomic Energy Agency (IAEA). 2003. Guidelines for radioelement mapping using gamma ray spectrometry data. IAEA-TECDOC-1363. Vienna (Austria).

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Dentith M, Mudge ST. 2014. Geophysics for the mineral exploration geoscientist. Cambridge (United Kingdom): Cambridge University Press.

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