Depositional environments signatures, maturity and source weathering of Niger Delta sediments from an oil well in southeastern Delta State, Nigeria

Yıl 2017, Cilt: 6 Sayı: 3, 259 - 274, 01.07.2017

Samuel Oni Akinade Olatunji

https://doi.org/10.18393/ejss.297245

Cited By: 4

Öz

Attempts have been made to
classify the sediment on their degree of maturity. Compositional maturity is a
reflection of intensity of weathering and a function of labile grains,
unstable/stable rock fragments and stable quartz arenites. The main aim of this
study is to investigate maturity and area of deposition and attempt to shed
light on source area paleo-weathering conditions. Twenty one samples of shales
and sandstones units were collected from a depth precisely between 1160 to
11,480m at a well in western Niger Delta, grinded, pulverized and sieved with
less than 75μm. About 10g was packed and sent to Acme analytical Laboratory
LTD., Vancouver, Canada. From the results, various plots and indexes inferring
maturity and area of deposition were utilized. Using the A-K-F ternary plots of
Englund and Jørgensen (1973), the depositional
environment is transition zone. The silicate weathering indexes CIA, CIW and
PIA values ranges from 45-65, on average indicates low to moderate weathering
in the source area with extreme weathering of some sand fraction. Various
calculated values of the weathering indices: Chemical Index of Alteration
(CIA), Plagioclase Index of Alteration (PIA), Chemical Index of Weathering
(CIW) and scatter plots of formulated ratios of Al/Na, K/Na, and Rb/K vs
chemical index of alteration (CIA) were plotted. The moderate values below
average suggest low to moderate weathering conditions in the source area or
during transportation. This also inferred their recycling processes are
insignificant. The clay content is low and feldspars are averagely high
implying immaturity. The calculated ZTR index for the sand ranges from
36.4-75.0 from with an average mode of 55.5% implying almost all contain
mineralogically immature sediments. The calculated Zircon- Tourmaline-Rutile
(ZTR) index shows that majority of the sample depths have >43% ZTR index but
below 75% which corresponds to generally immature sediments.

Anahtar Kelimeler

PIA, CIW, CIA, AKF, ZTR index, weathering index, Niger delta, immature sediments, depositional environments

Kaynakça

• Abd El-Rahman, Y., Polat, A., Dilek, Y. Fryer, B. El-Sharkawy, M. Sakran, S., 2009. Geochemistry and tectonic evolution of the Neoproterozoic Wadi Ghadir ophiolite, Eastern Desert, Egypt. Lithos 113(1-2): 158-178.
• Akarish, A.I.M., Dessandier, D., 2011. Characterization and Source of sedimentary rocks of the Alexandria lighthouse Archeological objects, Egypt. Journal of Applied Sciences 11(14): 2513-2524.
• Avbovbo, A.A., 1978. Tertiary lithostratigraphy of Niger Delta: Geologic Notes. American Association of Petroleum Geologists Bulletin 62(2): 295-300.
• Chaudhuri, S., Brookings, D.G., 1979. The Rb Sr systematic in acid-leached clay minerals. Chemical Geology 24(3-4): 231–242.
• Colin, R., Chaumery, C.J., Guermeur, E.I., 1997. Organo-tin concentrations in Brest Naval Port, in 1993 and 1994. Annales de l'Institute Oceanographique 73(1):17-24
• Doust, H., Omatsola, E., 1990. Niger Delta. In: Divergent/passive Margin Basins. Edwards, J.D., Santogrossi, P.A. (Eds). AAPG Memoir 48, American Association of Petroleum Geologists, Tulsa, Oklahoma, USA. p. 239-248.
• Englund, J.O., Jørgensen, Dr.P., (1973): A chemical classification system for argillaceous sediments and factors affecting their composition. Geologiska Föreningens i Stockholm Förhandlingar 95(1): 87-97.
• Evamy, B.D., Haremboure, J., Kamerling, P., Knaap, W.A., Molloy, F.A., Rowlands, P.H., 1978. Hydrocarbon habitat of Tertiary Niger Delta. American Association of Petroleum Geologists Bulletin 62(1): 277- 298.
• Fedo, C.M., Nesbit, H.W., Young, G.M., 1995. Unravelling the effect of potassium metasomatism in sedimentary rocks and paleosols, with implications of paleoweathering conditions and provenance. Geology 23(10): 921-924.
• Fedo, C.M., Eriksson, K.A., Krogstad, E.J., 1996. Geochemistry of shales from the Archean (~3.0 Ga) Buhwa Greenstone Belt, Zimbabwe: implications for provenance and source-area weathering. Geochimica et Cosmochimica Acta 60(10): 1751–1763.
• Feo-Codecido, G., 1956. Heavy minerals techniques and their application to Venezuela stratigraphy. American Association of Petroleum Geologists Bulletin 40(5): 984-1000.
• Galehouse, J S., 1971. Sedimentation analysis. In: Procedures in Sedimentary Petrology. Carver, R.E. (Ed.),. Wiley-Interscience. New York, USA. pp. 69-94.
• Harnois, L., 1988. The CIW index: A new chemical index of weathering. Sedimentary Geology 55(3-4): 319–322.
• Herron, M.M., 1988. Geochemical classification of terrigenous sands and shales from core and log data. Journal of Sedimentary Petrology 58: 820- 829
• Hubert, J.F., 1962. A zircon-tourmaline-rutile maturity index and the interdependence of the composition of heavy mineral assemblages with the gross composition and texture of sandstones. Journal of Sedimentary Petrology 32(3): 440-450.
• Jacobson, A.D., Blum, J.D., Chamberlian, C.P., Craw, D., Koons, P.O., 2003. Climate and tectonic controls on chemical weathering in the New Zealand Southern Alps. Geochimica et Cosmochimica Acta 67(1): 29–46.
• Krynine, P.D., 1946. The tourmaline group in sediments. The Journal of Geology 54(2): 65-87.
• Kulke, H., 1995. Nigeria. In: Regional Petroleum Geology of the World. Part II: Africa, America, Australia and Antarctica. Kulke, H., (Ed.). Gebrüder Borntraeger, Berlin. pp. 143-172.
• Ma, Y., Liu, C., Huo, R., 2000. Strontium isotope systematics during chemical weathering of granitoids: importance of relative mineral weathering rates. Journal of Conference Abstracts 5(2): 657.
• McLennan, S.M., 2001. Relationships between the trace element composition of sedimentary rocks and upper continental crust. Geochemistry, Geophysics, Geosystems 2(4). Paper number 2000GC000109
• McLennan, S. M., Hemming, S., McDaniel, D. K., Hanson, G. N., 1993. Geochemical approaches to sedimentation, provenance, and tectonics. In: Processes controlling the composition of clastic sediments. Johnsson, M. J., Basu, A., (Eds.). The Geological Society of America, Special Paper 284. Colorado, USA. pp. 21-40.
• Nesbitt, H.W., Young, G.M., 1982. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 199: 715-717.
• Nesbitt, H.W., Young, G.M., 1984. Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations. Geochimica et Cosmochimica Acta 48(7): 1523-1534.
• Nesbitt, H.W., Young, G.M., 1989. Formation and diagenesis of weathering profiles. The Journal of Geology 97(2): 129-147.
• Nesbitt, H.W., Young, G.M., 1996. Petrogenesis of sediments in the absence of chemical weathering: effects of abrasion and sorting on bulk composition and mineralogy. Sedimentology 43(2): 341–358.
• Odumoso, S.E., Oloto, I., Omoboriowo, A.O., 2013. Sedimentological and depositional enviroment of the Mid-Maastritchtian Ajali Sandstone, Anambra Basin, Southern Nigeria. International Journal of Science and Technology 3(1): 26-33.
• Ofoegbu, C.O., 1984. Interpretation of aeromagnetic anomalies over the Lower and Middle Benue Trough of Nigeria. Geophysical Journal International 79(3): 813–823.
• Oni, S.O., Olatunji, A.S., Ehinola, O.A., 2014. Determination of provenance and tectonic settings of Niger Delta clastic facies using well-y, Onshore Delta State, Nigeria. Journal of Geochemistry. Article ID 960139.
• Osae, S., Asiedu, D.K., Banoeng-Yakubo, B., Koeberl, C., Dampare, S.B., 2006. Provenance and tectonic setting of Late Proterozoic Buem sandstones of southeastern Ghana: Evidence from geochemistry and detrital modes. Journal of African Earth Sciences 44(1): 85-96.
• Pettijohn, F.J., 1941. Persistence of heavy minerals and geologic age. The Journal of Geology 49(6): 610-625.
• Pettijohn, F.J., Potter, P.E., Siever, R., 1972. Sands and Sandstones. Springer-Verlag, New York, USA. 552p.
• Ruxton, B.P., 1968. Measures of degree of chemical weathering of rocks. The Journal of Geology 76(5): 515-527.
• Short, K. C., and Stäublee, A.J., 1965. Outline of geology of Niger Delta. American Association of Petroleum Geologists Bulletin 51(5): 761- 779.
• Stacher, P., 1995. Present understanding of the Niger Delta hydrocarbon habitat. In: Geology of Deltas. Oti, M.N., Postma, G., (Eds.). AA Balkema Publishers, Rotterdam. pp. 257-267.
• Wronkiewicz, D.J., Condie, K.C., 1989. Geochemistry and provenance of sediments from the Pongola Supergroup, South Africa: evidence for a 3.0-Ga-old continental craton. Geochimica et Cosmochimica Acta 53(7): 1537–1549.
• Xiao, H., Suppe, J., 1992. Origin of rollover. American Association of Petroleum Geologists Bulletin 76(4): 509-229