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- Title
Geochemical Discriminant for Provenance, Source Area Weathering and Paleoredox of Some Shale Deposits in Edo State, Nigeria.
- Authors
Ilevbare, Martins; A., Adeleye Rita
- Abstract
The shale samples from Uzebba, Ayoguiri, and Ugbenor within Edo State, Anambra basin, southern Nigeria, were geochemically analyzed for major oxides, trace elements, and mineral content. The trace element ratios from the paleoredox inferences revealed that the shale samples were deposited in an oxic environment (Ni/Co, V/Cr, and V/V+Ni) except for V/Ni which was deposited in a dysoxic - oxic environment. The ancient climate condition of the shale was a semi-arid climate with increasing chemical maturity and the bivariate relations (SiO2 vs. Al2O3) authenticating that the shale was terrestrially sourced. The Al2O3/TiO2 (13.48) indicates that the provenance of the shale is from a felsic source. The bivariate relationship of (SiO2 vs. Al2O3+Na2O+K2O) suggests a semi-arid paleoclimate with increasing chemical maturity in a phanerozoic shale environment. The data obtained from the study, showed that the average values of the following weathering indices: the Plagioclase Index of Alteration (PIA) with a value of 91.00% (73.58-98.43), the Chemical Index of Alteration (CIA) of value 74.33% (65.18-78.25), the Chemical Index of Weathering (CIW) with a value of 93.12% (73.58-98.43) and the Mineralogical Index of Alteration (MIA) valued at 48.67% (30.36-56.50) which indicates a substantial, moderate to intense chemical weathering with a PIA average indicating a phenerozoic ancient environment. The mineralogy of the shale from the diffractogram profiles were quartz, fluorapatite, calcite and montmorillonite. The predominance of quartz again confirms the resistance of quartz to weathering conditions while the other minerals that are in trace amounts are only indications that they are less resistant to weathering and have dissolved in the solution.
- Subjects
EDO State (Nigeria); WEATHERING; GEOCHEMISTRY; FELSIC rocks; TRACE element analysis; PALEOCLIMATOLOGY
- Publication
Jordan Journal of Earth & Environmental Sciences, 2023, Vol 14, Issue 4, p258
- ISSN
1995-6681
- Publication type
Article