##plugins.themes.bootstrap3.article.main##

Mineralogical and paleocurrent studies of Amasiri Sandstone, a member of Ezeaku Group outcropping as a ridge in Abini were done to determine the quantitative values of component minerals for proper designation of the facies of sandstone and the direction of paleocurrent. Sampling, paleocurrent measurements, petrographic and X-ray diffraction (XRD) analyses were employed to achieve results. Three highly indurated beds of white fine – medium, angular - subrounded grained sandstones were observed. The basal and second beds had thin laminations, whereas the third was massive. The sandstone is found to be hybrid facies, it is not a quartz arenite neither a calcareous sandstone. Calcite (CaCo3) is the most abundant mineral ranging from 43% - 66%, with an average of 51.39%. Calcite is seen occurring as skeletal grains and sparry calcite, corroding, and replacing quartz grains. Quartz (SiO2) ranges from 3% - 37.6% with an average of 17.22%, occurring as detrital quartz and authigenic quartz overgrowth. Monocrystalline and polycrystalline quartz occur, with monocrystalline dominating. Feldspars such as albite, plagioclase, sanidine and orthoclase occur, with the potasssic feldspars dominating. Silica, calcite, and iron oxide were the observed cementing materials. The paleocurrent direction is in the SE. The angularity of the grains implies a source area with close proximity. Therefore, the source area could be inferred to be the Oban Massif or and the Cameroun Mountains.

References

  1. Pettijohn FJ. Sedimentary rocks, Third edition, CBS publishers and distributors, 2004.
     Google Scholar
  2. Doyle Larry J. Roberts, Harry H. Editors. Carbonate clastic transition (Developments in sedimentology). Published by Elsevier Science Publishers., Amsterdam, Oxford et. al. (1988) ISBN 10: 0444429042 ISBN 13: 9780444429049.
     Google Scholar
  3. Simpson, A. The Nigerian coalfield: Geology of parts of Onitsha, Owerri and Benue provinces. Bull. GSN, 1995;24:85.
     Google Scholar
  4. Murat RC. Stratigraphy and paleogeography of Cretaceous Lower Tertiary in southern Nig. African Geol. TFJ. Dessauvagie and MD. Whiteman (Ed), University of Ibadan press, 1972, 251-268.
     Google Scholar
  5. Umeji OP. Ammonite palaeoecology of the Ezeaku Formation, southeastern Nigeria. Journal of Mining and Geology, 1984, vol. 21, pp 55-59.
     Google Scholar
  6. Ekueme BN, Nyong EE, Peters,SW. Geological excursion guidebook to Oban Massif, Calabar Flank and Mamfe Embayment. Dec-Ford Publishers, Calabar, 1995.
     Google Scholar
  7. Akpofure E. and Didei SI. Sedimentology of the Turonian Ezeaku Sandstone in the Afikpo Basin, Nigeria. International Journal Geology and Mining, 2018; 4(2):211-223.
     Google Scholar
  8. Hoque M. Petrographic differentiation of tectonically controlled Cretaceous sedimentary cycles, South Nigeria. Journal of Sedimentary Geology, 1977;17:235-245.
     Google Scholar
  9. Reyment RA. Aspects of geology of Nigeria. Ibadan university press, 1965, p. 133.
     Google Scholar
  10. Nwajide CS. Geology of Nigeria’s sedimentary basins. Lagos, CSS Press, 2013.
     Google Scholar
  11. Peters SW, Nyong EE, Akpan EB, Essien NU. Lithostratigraphic revision for the Calabar Flank, SE Nigeria. In Proc. of the 31st Ann. Conf. of NMGS.
     Google Scholar
  12. Amajor LC. The Eze-Aku Sandstone ridges (Turonian) of southeastern Nigeria. A re-interpretation of their depositional origin. Nigerian Journal of mining and Geology, 1987;23(1&2):19-26.
     Google Scholar