Source-Area Weathering, Composition and Paleo-Redox Condition of Stream Sediments from Ijero-Ekiti, Nigeria

Geochemical study of some stream sediments in Ijero-Ekiti was carried out to deduce their provenance, paleo-redox environment and source-area weathering. The SiO2/(Al2O3+K2O+Na2O) ratios for the paleoclimate during deposition indicates the arid/semi-arid conditions. This moderate climate will give rise to moderate weathering process. The weathering indices (CIA, CIW, PIA and MIA) and the A'“CN'“K Ternary diagram indicate a moderate degree of weathering of the source materials. The average Th/U ratio of the stream sediments is 1.66, which also suggests moderate degree of weathering of the source material. The stream sediments were enriched in both TiO2 and Zr, which implies that the stream sediments may have originated from a felsic source. The bivariate plot of Na2O-K2O shows that all the samples are quartz-rich, which suggests that they may be of felsic origin. The provenance discriminant function plot shows the samples plotted mainly in the felsic igneous and quartzose sedimentary zones. The TiO2 versus Zr plot shows all the stream sediments plotting in felsic zone; average Cr/V ratio for sediments is 1.49, while the Y/Ni ratio is 0.98; suggesting a felsic source. Bivariate plots Ti versus Ni and K versus Rb revealed that the samples are of acidic/felsic intermediate composition. The ternary plot of La-Th-Sc of the analyzed samples suggest derivation from felsic rocks of granite and granodiorite composition. However, In the ternary diagram of V-Ni-Th*10, all the samples plotted in the mafic source area. Element ratios such as U/Th, Ni/Co, Cu/Zn, (Cu+Mo)/Zn, V/Cr and V/Sc indicate that the stream sediments were deposited under oxic conditions. V/(Ni+V) ratios indicate suboxic to anoxic environment of deposition while the Mn* values suggests oxic and suboxic environment. Henry Y. Madukwe"Source-Area Weathering, Composition and Paleo-Redox Condition of Stream Sediments from Ijero-Ekiti, Nigeria" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-5 , August 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2365.pdf http://www.ijtsrd.com/other-scientific-research-area/geology/2365/source-area-weathering-composition-and-paleo-redox-condition-of-stream-sediments-from-ijero-ekiti-nigeria/henry-y-madukwe