Publisher: Chemical Society of Nigeria

Use of Toc, Som and Porphyrin As Indices For Reconstructing Sedimentation Pattern As Exemplified By Campano- Maastrichtian Shales of Nkporo Formation, Calabar Flank, Southeastern Nigeria.

K. A. Ibe, V. N. Osabor
KEYWORDS: Porphyrins, paleoenvironment, outcrops, depositional cycle, sedimentation.


Thirty outcrop samples from Nkporo formation in Calabar Flank, Southeastern Nigeria were analysed for total organic carbon, soluble organic matter and porphyrins. The values of the total organic carbon (TOC) ranged from 1.78 to 4.3% while those of the soluble organic matter (SOM) ranged from 110.5 to 4550ppm. The ratio of nickel- summation of nickel & vanadium porphyrins ranged from 0.15 to 1.00. The pattern of variation of the TOC and SOM values (spasmodic drop in systematic variation) depicts a multi- cycle sedimentation pattern. And the reconstructed paleoenvironment using the porphyrinic ratios was predominantly oxidizing. However, the TOC values were mostly greater than 2.5%, suggesting that conditions that generate reducing environment existed

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