Reconstruction of the primary organic productivity of Campano-Maastrichtian shales of Nkporo and Aptian-Albian Awi Formations, Calabar Flank using pigment yield index
K. Ibe1, C. Ogwuche1
1Federal University of Petroleum Resources, Effurun, Nigeria
Min. miner. depos. 2018, 12(3):113-118
https://doi.org/10.15407/mining12.03.113
Full text (PDF)
ABSTRACT
Purpose. To derive the paleo organic productivity exemplified by the pigment yield index in order to resolve the controversy on the petroleum potentials of Nkporo and Awi Formations in Calabar Flank, Southeastern Nigeria.
Methods. Twenty outcrop samples each from Nkporo and Awi Formations in Calabar Flank, Southeastern Nigeria were analysed for total organic carbon, soluble organic matter and pigment richness by Walkley Black method, soxhlet extraction and column chromatography in order to derive the pigment yield index associated with paleo organic productivity which is needed to assess the petroleum potential.
Findings. The geochemical analysis results of the total organic carbon, soluble organic matter, pigment richness showed that the outcrop samples had organic matter and hydrocarbon above the threshold required for petroleum generation and that the samples were deposited in predominantly anoxic setting.
Originality. The results of the organic carbon (TOC) for Nkporo Formation – 1.51 to 4.30%; Awi Formation – 0.75 – 6.40%; soluble organic matter (SOM) Nkporo Formation – 110.5 to 4550.0 ppm and Awi Formation – 288.50 – 2664.25 ppm attest to the above threshold petroleum potential. Ni/Ni + VoP ratios for both Nkporo and Awi Formations < 0.5 to > 0.6 showed anoxic, paralic and oxic settings, though predominantly anoxic, excellent for organic matter preservation. Pigment yield indices of 5.88 and 5.58 equally depicts high petroleum potentials for the two Formations.
Practical implications. These results can be used to assess the paleo bioproductivity which is primary in petroleum generation, and in the resolution of controversies in the comparative assessment of two or more basins or formations.
Keywords: porphyrins, pigment yield index, outcrops, paleo organic productivity, petroleum potential
REFERENCES
Adeleye, J.B., & Fayose, E.A. (1978). Depositional environments of carbonates, Calabar Flank, Nigeria. Journal Mi-neral Geology, (15), 1-13.
Baker, E.W., & Louda, J.W. (1980). Products of chlorophyll diagenesis in Japan Trench Sediments, Deep Sea Drilling Project Sites 438, 439, and 440. Initial Reports of the Deep Sea Drilling Project, 56/57.
https://doi.org/10.2973/dsdp.proc.5657.172.1980
Demaison, G.J., & Moore, G.T. (1980). Anoxic environments and oil source bed genesis. Organic Geochemistry, 2(1), 9-31.
https://doi.org/10.1016/0146-6380(80)90017-0
Didyk, B.M., Simoneit, B.R.T., Brassel, S.C., & Eglinton, G. (1978). Organic geochemical indicators of palaeoenvironmental conditions of sedimentation. Nature, 272(5650), 216-222.
https://doi.org/10.1038/272216a0
Edet, J.J., & Nyong, E.E. (1994). Palynostratigraphy of Nkporo Shale exposures (late Campanian-Maastrichtian) on the Calabar Flank, SE Nigeria. Review of Palaeobotany and Palynology, 80(1-2), 131-147.
https://doi.org/10.1016/0034-6667(94)90098-1
Ekpo, B.O., Essien, N., Fubara, E.P., Ibok, U.J., Ukpabio, E.J., & Wehner, H. (2013). Petroleum geochemistry of Cretaceous outcrops from the Calabar Flank, Southeastern Nigeria. Marine and Petroleum Geology, (48), 171-185.
https://doi.org/10.1016/j.marpetgeo.2013.08.011
Essien, N.U., Ukpabio, E.J., Nyong, E.E., & Ibe, K.A. (2005). Preliminary organic geochemical appraisal of Cretaceous rock units in the Calabar Flank, Southeastern Nigeria. Journal of Mining and Geology, 41(2), 185-191.
Grosjean, E., Adam, P., Connan, J., & Albrecht, P. (2004). Effects of weathering on nickel and vanadyl porphyrins of a Lower Toarcian shale of the Paris basin. Geochimica et Cosmochimica Acta, 68(4), 789-804.
https://doi.org/10.1016/s0016-7037(03)00496-4
Hodgson, G.W., Flores, J., & Baker, B.L. (1969). The origin of petroleum porphyrins: preliminary evidence for protein fragments associated with porphyrins. Geochimica et Cosmochimica Acta, 33(4), 532-535.
https://doi.org/10.1016/0016-7037(69)90134-3
Ibe, K.A., & Osabor, V.N. (2014). Use of TOC, SOM and Porphyrin indices for reconstructing sedimentation pattern as exemplified by Campano-Maastrichtian shales of Nkporo formation, Calabar Flank, Southeastern Nigeria. Journal Chemical Society of Nigeria, 39(1), 14-20.
Moldowan, J.M., Sundararaman, P., & Schoell, M. (1986). Sensitivity of biomarker properties to depositional environment and/or source input in the Lower Toarcian of SW-Germany. Organic Geochemistry, 10(4-6), 915-926.
https://doi.org/10.1016/s0146-6380(86)80029-8
Murat, R.C. (1972). In dessauvagie and whiteman. African Geology, 251-266.
Nyong, E.E., & Ramanathan, R. (1985). A record of oxygen circulation in lacustrine environment of Niger Delta. Paleoclimatology, (102), 161-163.
Petters, S.W. (1982). Central West African Cretaceous-Tertiary benthic foraminifera and stratigraphy. Palaeontographica A: Paleozoology, Stratigraphy, (179), 1-3.
Ramanathan, I.R., Kumaran, I. (1981). An upper Cretaceous assemblage from Nkporo shale of Calabar Flank, Nigeria. Journal Paleontology Society of India, (31), 9-13.
Reijers, T.J.A., & Petters, S.W. (1987). Depositional environments and diagenesis of Albian carbonates on the Calabar Flank, Southeastern Nigeria. Journal of Petroleum Geology, 10(3), 283-294.
https://doi.org/10.1111/j.1747-5457.1987.tb00947.x
Reyment, R.A. (1980). Review of Nigerian cretaceous cenozoic stratigraphy. Journal of Mineral Geology, 2(2), 61-80.
Reyment, R.A., & Dingle, J. (1987). Aspects of geology of Nigeria. Ibadan, Nigeria: Ibadan University Press.
Stein, R., Rullkotter, J., Kalkreuth, W., & Welte, D.H. (1987). Quantity, provenance, and thermal maturity of organic matter from the New Jersey Continental Margin, Deep Sea Drilling Project Leg 95. Initial Reports of the Deep Sea Drilling Project.
https://doi.org/10.2973/dsdp.proc.95.128.1987
Walkley, A., & Black, I.A. (1934). An examination of the degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil Science, 37(1), 29-38.
https://doi.org/10.1097/00010694-193401000-00003
Wignal, P.B., & Twitchet, R.J. (2002). Geological society. America Special Paper, 356-395.
