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Universal Journal of Geoscience(CEASE PUBLICATION) Vol. 3(3), pp. 71 - 82
DOI: 10.13189/ujg.2015.030301
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Depositional Setting of Sandstones from the Oligocene-Miocene Ogwashi-Asaba Formation, Niger Delta Basin, Nigeria: Evidence from Grain Size Analysis and Geochemistry

Ejeh O. Innocent , Akpoborie I. Anthony ^*, Etobro, A. A. Israel
Department of Geology, Delta State University, Nigeria

ABSTRACT

Field observations at freshly exposed quarry sites, grain size analysis, mass spectrometry and statistical methods have been used to determine the depositional setting of sandstones from the Oligocene-Miocene Ogwashi-Asaba Formation. Some of the sandstones are ferruginized and indurated; others are friable, cross-bedded, non-ferruginized, white to yellow to reddish brown on weathering, and show top/bottom mantled pebbles. Textural examination indicates that the sandstones range from fine to coarse sands, with graphic mean grain size of -0.3 to 2.13筛. Standard deviation ranges from 0.62 to 1.52筛 and implies moderately sorted to poorly sorted sediments. Textural indices suggest that most of the sediments were deposited under fluvio-deltaic to shallow marine environment by fluvial and beach processes adjacent to a near shore whirlpool agitating turbidity conditions. Major elemental oxides show SiO₂ content > 71% with extreme depletion of mobile oxides such as Na₂O, CaO and the ferromagnesian minerals through weathering and sedimentary processes.

KEYWORDS
Niger Delta Basin, Ogwashi-Asaba Formation, Sandstones, Geochemistry, Depositional Setting

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Ejeh O. Innocent , Akpoborie I. Anthony , Etobro, A. A. Israel , "Depositional Setting of Sandstones from the Oligocene-Miocene Ogwashi-Asaba Formation, Niger Delta Basin, Nigeria: Evidence from Grain Size Analysis and Geochemistry," Universal Journal of Geoscience(CEASE PUBLICATION), Vol. 3, No. 3, pp. 71 - 82, 2015. DOI: 10.13189/ujg.2015.030301.

(b). APA Format:
Ejeh O. Innocent , Akpoborie I. Anthony , Etobro, A. A. Israel (2015). Depositional Setting of Sandstones from the Oligocene-Miocene Ogwashi-Asaba Formation, Niger Delta Basin, Nigeria: Evidence from Grain Size Analysis and Geochemistry. Universal Journal of Geoscience(CEASE PUBLICATION), 3(3), 71 - 82. DOI: 10.13189/ujg.2015.030301.