Geochemical signatures of siliciclastic rocks constituting the sedimentary fill of a basin can provide useful clues for constraining sedimentary processes. The inorganic geochemical composition of interbedded sandstone and shale in hydrocarbon-producing zones of the Agbada Formation (Niger Delta Basin) were used as proxies to determine the provenance signatures, evaluate weathering intensity in the source area, and reconstruct paleo-redox conditions in the depositional environment. The Al2O3-(CaO + Na2O)–K2O relationship, Th/U ratio, CIA versus SiO2 correlation, and other weathering proxies (CIA, CIX, aAlE indices) indicate moderate to intense weathering conditions in the source area. Various elemental ratios such as La/Co, Cr/Th, Eu/Eu*, (La/Lu)N, Th/Co, LHREE/HREE (light to heavy rare earth elements), and the Eu anomaly suggest predominantly felsic sources. Other ratios (e.g., V/Cr, Ni/Co, Cu/Zn, Mo-EF/U-EF) sensitive to redox conditions reflect an oxic-suboxic depositional environment. The interbedded sandstones and shales reflect insignificant disparity in terms of their source area weathering and provenance.
Overare, B., Azmy, K., Garzanti, E., Osokpor, J., Ogbe, O., Avwenagha, E. (2021). Decrypting geochemical signatures in subsurface Niger delta sediments: Implication for provenance, weathering, and paleo-environmental conditions. MARINE AND PETROLEUM GEOLOGY, 126(April 2021), 1-20 [10.1016/j.marpetgeo.2020.104879].
Decrypting geochemical signatures in subsurface Niger delta sediments: Implication for provenance, weathering, and paleo-environmental conditions
Garzanti E.Penultimo
Membro del Collaboration Group
;
2021
Abstract
Geochemical signatures of siliciclastic rocks constituting the sedimentary fill of a basin can provide useful clues for constraining sedimentary processes. The inorganic geochemical composition of interbedded sandstone and shale in hydrocarbon-producing zones of the Agbada Formation (Niger Delta Basin) were used as proxies to determine the provenance signatures, evaluate weathering intensity in the source area, and reconstruct paleo-redox conditions in the depositional environment. The Al2O3-(CaO + Na2O)–K2O relationship, Th/U ratio, CIA versus SiO2 correlation, and other weathering proxies (CIA, CIX, aAlE indices) indicate moderate to intense weathering conditions in the source area. Various elemental ratios such as La/Co, Cr/Th, Eu/Eu*, (La/Lu)N, Th/Co, LHREE/HREE (light to heavy rare earth elements), and the Eu anomaly suggest predominantly felsic sources. Other ratios (e.g., V/Cr, Ni/Co, Cu/Zn, Mo-EF/U-EF) sensitive to redox conditions reflect an oxic-suboxic depositional environment. The interbedded sandstones and shales reflect insignificant disparity in terms of their source area weathering and provenance.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.