Environmental Geochemistry and Health

, Volume 38, Issue 4, pp 1029–1035 | Cite as

Positive anomalous concentrations of Pb in some gabbroic rocks of Afikpo basin southeastern Nigeria

  • J. N. Onwualu-John
Original Paper


Gabbroic rocks have intruded the sedimentary sequence at Ameta in Afikpo basin southeastern Nigeria. Petrographic and geochemical features of the rocks were studied in order to evaluate their genetic and geotectonic history. The petrographic results show that the rocks contain plagioclase, olivine, pyroxene, biotite, iron oxide, and traces of quartz in three samples. Major element characteristics show that the rocks are subalkaline. In addition, the rocks have geochemical characteristics similar to basaltic andesites. The trace elements results show inconsistent concentrations of high field strength elements (Zr, Nb, Th, Ta), moderate enrichment of large-ion lithophile elements (Rb, Sr, Ba) and low concentrations of Ni and Cr. Rare earth element results show that the rocks are characterized by enrichment of light rare earth elements, middle rare earth elements enrichment, and depletion of heavy rare earth elements with slight positive europium anomalies. Zinc concentrations are within the normal range in basaltic rocks. There are extremely high concentrations of Pb in three of the rock samples. The high Pb concentrations in some of these rocks could be as a result of last episodes of magmatic crystallization. The rocks intruded the Asu River Group; organic components in the sedimentary sequence probably contain Pb which has been assimilated into the magma at the evolutionary stage of the magma. Weathering of some rocks that contain galena could lead to an increase in the concentration of lead in the gabbroic rocks, especially when the migration and crystallization of magma take place in an aqueous environment. Nevertheless, high concentration of lead is hazardous to health and environment.


Gabbroic rocks Ameta Southern Benue Trough Lead (Pb) 


  1. Amajor, L. C., Ofoegbu, C. O., & Okeke, P. O. (1988). Chemical evidence for the ultimate origin of the highly altered Cretaceous basalts, Southern Benue Trough, Nigeria. Geochemistry, Mineralogy and Petrology, 25, 68–84.Google Scholar
  2. Burke, K., Dessauvagie, T. F. J., & Whiteman, A. J. (1971). Opening of the Gulf of Guinea and the geological history of the Benue depression and Niger Delta. Nature Physical Science, 233, 51–55.CrossRefGoogle Scholar
  3. Cox, K.G., Bell, J.D., & Pankhurst, R.J. (1979). The interpretation of Igneous rocks (p. 450). London: George Allen and Unwin Ltd.Google Scholar
  4. Fairhead, J. D., & Okereke, C. S. (1987). A regional gravity study of the West African rift system in Nigeria and Cameroon and its tectonic implication. Tectonophysics, 143, 141–159.CrossRefGoogle Scholar
  5. Floyd, P. A., & Winchester, J. A. (1975). Magma type and tectonic setting discrimination using immobile elements. Earth and Planetary Science Letters, 27, 211–218.CrossRefGoogle Scholar
  6. Irvine, T.N. & Baragar, W.R.A.(1971). A guide to the chemical Classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8(5), 523–548. doi: 10.1139/e71-055.
  7. O’Hara, M. J. (1965). Importance of the ‘shape’ of the melting regime during partial melting of the mantle. Nature, 314, 58–62.CrossRefGoogle Scholar
  8. Odigi, M. I., & Amajor, L. C. (2009). Brittle deformation in the Afikpo basin, southern Nigeria: evidence for a terminal cretaceous extensional regime in the lower Benue Trough, Nigeria. Chinese Journal of Geochemistry, 28, 369–376.CrossRefGoogle Scholar
  9. Onwualu-John, J. N., & Ukaegbu, V. U. (2009a). Petrogenetic and geotectonic implication of Lokpa Ukwu pyroclastics in Southern Benue Trough, Nigeria. The Pacific Journal of Science and Technology, 10(1), 487–498.Google Scholar
  10. Onwualu-John, J. N., & Ukaegbu, V. U. (2009b). Geochemistry of the association of syenodiorites and pyroclastics in the Southern Benue Trough, Nigeria: petrogenetic and tectonic implications. World Journal of Applied Science and Technology, 1(1), 11–27.Google Scholar
  11. Onwualu-John, J. N., & Ukaegbu, V. U. (2010). Alkaline magmatism in the lower Benue Trough, Southeastern Nigeria: a geochemical evaluation. The IUP Journal of Sciences, 4(4), 23–48.Google Scholar
  12. Pearce, J.A. (1975). Basalt geochemistry used to investigate past tectonic environment in cyprus. Tectonophysics, 25(5), 41–67.CrossRefGoogle Scholar
  13. Pearce, J. A., & Cann, J. R. (1971). Ophiolite origin investigated by discriminate analysis using Ti, Zr and Y. Earth and Planetary Science Letters, 12, 339–349.CrossRefGoogle Scholar
  14. Rollinson, H. R. (1995). Using geochemical data: evaluation, presentation, interpretation. Longman Geochemistry series. London: Longman House.Google Scholar
  15. Wood, D. A., Joron, J. L., & Treuil, M. (1979). A re-appraisal of the use of trace elements to classify and discriminate between magma series erupted in different tectonic settings. Earth and Planetary Science Letters, 45, 326–336.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  1. 1.Department of GeologyUniversity of Port HarcourtPort HarcourtNigeria

Personalised recommendations