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Research Paper | Geology | Nigeria | Volume 12 Issue 4, April 2023
Geochemistry and Depositional Environment of Shale Deposit in Nanim Field Offshore Niger Delta, Nigeria
Abstract: In this study, shale deposits from offshore wells in Nanim Field, Niger Delta were evaluated geochemically to establish the paragenesis of the studied section and thereafter, determine the conditions that control the depositional environments in the area. Shale samples were grinded, pulverized and sieved with less than 75?m and analyzed using X-ray fluorescence (XRF) for elemental analysis and X-ray diffraction techniques (XRD) for mineralogical composition. The XRD for mineralogical analysis shows that the lower part of the section under study is characterized by quartz and kaolinite as the major crystalline minerals with trace of halloysite and minor quantities of other minerals. The XRF results reveal that SiO2 and Al2O3 are the predominant major oxides in the analyzed samples. Silica enrichment is a measure of sandstone maturity, and is a reflection of the duration and intensity of weathering and destruction of other minerals during transportation. The presence of hematite in the basal part of the shale outcrop suggests oxidizing diagenetic environment of deposition. The A-K-F ternary plot of the depositional environment shows a gradual transition of the sediments of the basin from transitional to marine environment and the binary plot also shows that the samples support the non-marine boundary and marine zone, majorly falling within the transition zone. The Carbonaceous zone indicates elevated amounts of organic matter of floral or faunal origin, which are indicative of reducing conditions. The binary plot can also be used to determine depositional environments. The binary plot shows that the samples align with the non-marine boundary (Fluvial deltaic terrain) and marine zone i. e. the Transition-marine zone, which are also sedimentary terrains.
Keywords: Geochemistry, Depositional environment, kaolinite and elemental analysis
Edition: Volume 12 Issue 4, April 2023,
Pages: 1093 - 1097