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Geochemical Analysis and Sedimentary Characteristics of the Nigerian Tar Sand; Implications on Classification, Maturity and Depositional Environment

Nwanekezi-Phil Chukwumerije G., Chukwu Chidinma N and Dr. Wale Akinmosin
Keywords: geochemical analysis, sedimentary characterstics, tar sand, despositional environment.

Cite ➜

Chukwumerije, N.G., Chidinma, C.N. and Dr. Akinmosin, W., 2021. Geochemical Analysis and Sedimentary Characteristics of the Nigerian Tar Sand; Implications on Classification, Maturity and Depositional Environment. United International Journal for Research & Technology (UIJRT), 2(5), pp.16-24.

Abstract

14 subsurface samples from 3 wells (denoted as well A, B, C,) were selected for analysis of geochemical and sedimentary characteristics for the purpose of inferring on sediment classification, maturity and paleo – depositional settings of the Afowo Formation of Dahomey Basin. The study areas are located at Ayede-Ajegunle with coordinate 6.58 N, 4.62 E as Well A, Araromi-Obu/Ago Alaye with coordinate 6.59 N, 4.54 E as Well B and Ajegunle with coordinate 6.60, 4.60 E as Well C.  Grain size analysis was carried out, parameters computed for were mean, mode, standard deviation, kurtosis, and skewness. Sediments from Well A range from fine to very fine grained sizes. However, samples between depth 69m and 72m have their grain sizes ranging from medium grained to very fine grained. The grains are moderately sorted to very well sorted, platykurtic to mesokurtic and symmetrically skewed. The grains from Well B range from fine to very fine grain sizes.

The grains are mostly moderately sorted, mesokurtic to very platykurtic and symmetrical to strongly coarse skewed. The result of grain size analysis for core samples from Well C are largely fine grained. The grains are moderately sorted, platykurtic and fine skewed. The sandstones found in wells B and C should be relatively closer to the distal position of the basin and reflect single source of sediment supply (largely unimodal). This is due to the comparatively narrow range of grain size observed. Multivariate analysis shows that the environment of deposition was dominated by fluvial activities.. Major elements analysis result showed higher SiO2 with an average of 69.3%, AlO3 with an average of 12.9% and Fe2O3 with an average of 3.49%.

Relevant crossplots with the oxides were used for classification, maturity index and depositional setting inference. From the crossplot of Log (Fe2O3/K20)/Log (SiO2), 11 of the sediments are classified as Iron Sands while 4 of the samples were classified as Iron Shale. Scatter plot of SiO2/Al2O3+K2O+Na2O shows that climatic conditions at   deposition were humid to semi – humid. The chemical index of alteration (CIA) values for the sampled locations ranges from 98.97-99.90 with an average of 98.61 while the chemical index of weathering (CIW) ranges from 98.21-99.89 with an average of 99.53. Observation from the thin section showed that quartz percentage made up 75% with the absence of feldspar and lithic fragment while iron makes up for the rest 25%.

Upon this, the ferruginous sandstones can be said to belong to the class of Quartz Arenites.  It is obvious that from the above results that the sediments were of fluvial origin and its source rock was exposed to intensive weathering which depicts matured sediments.

References

  1. Whiteman, Nigeria: Its Petroleum Geology, Resources and Potentials. Vol. 1 & 2 Graham and Trotman Ltd.: London, UK. 1982.
  2. K. Sahu, Depositional mechanisms from the size analysis of clastic sediments. J sed. petrol 34:73–83, 1964.
  3. P. Roser, and R.J. Korsch, Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio. J. Geol., 94: pp.635-650, 1968.
  4. P. Roser, R.A. Cooper, S. Nathan, and A.J. Tulloch, Reconnaissance sandstone geochemistry, provenance, and tectonic setting of the lower Paleozoic terrains of the West Coast and Nelson, New Zealand. New Zealand. J. Geol. Geophysics., 39: 1-16, 1996.
  5. Cingolani, M. Manassero, and P. Abre, Composition, provenance, and tectonic setting of Ordovician siliciclastic rocks in the San Rafael block: Southern extension of the Precordillera crustal fragment, Argentina: Journal of South American Earth Sciences, 16(1): 91-106, 2003
  6. H. Krinsley and J.C. Doornkamp, Atlas of Quarts surface Sand Texture, New York Cambridge University Press, and pp.91, 1973.
  7. R. Prothero, Sedimentary Geology New York; W.H. Freeman and company, 2004.
  8. I. Enu, Textural characteristics of the Nigerian Tar sands. Sedimentary geology. 44, pp. 65 – 81, 1985.
  9. I. Enu, The Paleoenvironment of deposition of late maastrichtian to paleocene black Shales in the Eastern Dahomey Basin, Nigeria. Geol. En mynbouw, pp. 15-20, 1987.
  10. W. Nesbitt, and G.M. Young, Early proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature, 299: pp. 715-717, 1982.
  11. Y. Madukwe, provenance, tectonic setting and maturity of the Ishara sandstone, south-western, Nigeria: insight from major element geochemistry, 2014.
  12. Hockey, The Geology of part of southwestern Nigeria. Geological Survey of Nigeria (GSN) Bulletin, 1964. vol 31, 101, 1994
  13. J. Weber, and E. Daukoro, Petroleum Geology of the Niger Delta. Ninth world petroleum congress, 2. pp. 209 – 221, 1997.
  14. O. Onuoha, Structural features of Nigerian coastal margins, an assessment based on age data from well. Journal of African Earth Science, V. 20/03, pp. 485 – 499, 1999.
  15. J. Suttner, P.K. Dutta, Alluvial sandstone composition and paleoclimate. L. Framework mineralogy. Journal of sedimentary petrology; Vol. 56, p. 329-345, 1986.
  16. A. Omatsola, and O.S. Adegoke, Tectonic Evolution and Cretaceous Stratigraphy of the Dahomey Basin. Journal of Mining Geology, Vol. 18, No. 1, pp. 130-137, 1981.
  17. Nton, Sedimentological and geochemical studies of rock units in the eastern Dahomey basin, south western Nigeria, unpublished P.H.D thesis, University of Ibadan, 2001, pp 315, 2001.
  18. A. Agagu, A geological guide to bituminous sediments in Southwestern Nigeria. Unpublished Report, Department of Geology University of Ibadan, 1985.
  19. S. Adegoke, B.D. Ako, E.I. Enu, Geotechnical investigations of the Ondo State bituminous sands. Vol. 1. Geology and reserve estimate. Rept. Geological Consulting Unit, Dept. of Geology, University ofIfe. 257pp, 1980.
  20. Oluwole et al., Chemical Composition of Bituminous Extracts of Nigeria Tar Sand. In: proceeding of 3rd intern confer. On heavy crude and Tar Sands: Long beach California; Chap. 33, pp. 373 – 379, 1985.
  21. Oshinowo et al., Bituminous Tar Sand of Nigeria, Analysis oils part 1. Journal of Nigerian Chemical Engineers, 1(1) 44 – 48, 1982.
  22. A. Reyment, Aspect of Geology of Nigeria, Ibadan University Press, pp. 77, 1965.
  23. C.C. Wilson and C.A. Williams, Oceanic transformation structures and the development of the Atlantic continental margin sedimentary basin review. Journal of Geological Society of London, V, 136, P, 311 – 320, 1979.
  24. L. Folk, and W.C. Ward, Brazos River Bar: A Study in the Significance of Grain Size Parameters. Journal of Sedimentary Petrology, Vol. 27, No. 1, pp. 3 – 26, 1957.
  25. I.J. Coker, and Ejedawe, J.E, Petroleum prospect of the Benin Basin Nigeria. Journal of Mining and Geology, V. 23(01), P. 7 -43, 1987.
  26. I.j. Cox,et al, The influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern United States: Geochemical et Cosmochimica Acta, vol. 59: p. 2919–2940, 1995.
  27. I.J. Coker, Heavy mineral potential with the mineable areas of the Okitipupa oil sand deposits, Nigeria. Abstracts .N.M.G.S Conf. Kaduna, 1990.

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