Provenance, Tectonic Setting and Source-Area Weathering of the Coastal Plain Sediments, South West, Nigeria by H.Y. Madukwe, R.A. Obasi, O.R. Fakolade, C.E. Bassey, Scientific Research Journal (Scirj), Volume III, Issue II, February 2015 Edition

Scirj Volume III, Issue II, February 2015 Edition
ISSN: 2201-2796

Provenance, Tectonic Setting and Source-Area Weathering of the Coastal Plain Sediments, South West, Nigeria

H.Y. Madukwe, R.A. Obasi, O.R. Fakolade, C.E. Bassey

Abstract: Major oxide geochemical analysis was carried out on the Coastal Plain sediments in the Dahomey Basin, to infer their provenance, tectonic setting and source-area weathering. The depletion of highly mobile K and Ca elements is due to leaching during the formation of clay minerals during increased chemical weathering. Na is a highly mobile element that is enriched, this may be due to secondary enrichment. Si is a less mobile element and its enrichment suggests moderate chemical weathering. The immobile Fe and Ti and the less mobile Mg elements were depleted, this suggest that they may be from a common source with more felsic minerals and dearth of ferromagnesian minerals. The high Al2O3/TiO2 ratio also suggests felsic source rock. The CIA values for the samples ranged between 9 and 30%, while CIW ranged from 10-32% indicating a very low degree of weathering of the source materials, suggestive of materials from reworked clastic sediments. The PIA values ranged from -43-28%, this also indicates very low weathering with the negative values suggesting rapid deposition of pre-existing clastic sediments with little or no weathering. MIA values for the samples indicates no weathering of the source material, which is not in agreement with the other weathering indices. The Coastal Plain sediments plotted in the plagioclase zone on the A–CN–K diagram, indicating little or no weathering for some samples. The weathering trend suggests that the sediments are rich in plagioclase feldspars without alteration to smectite. The ternary plot of SiO2/Al2O3, MgO and Fe2O3 indicated that the studied samples were deposited in the non-marine and deltaic settings. This observed trend is supported by the binary plot of Fe2O3 versus MgO. Provenance discrimination diagram shows that plots appeared in three provenance fields except P4 (main igneous) indicating that they are derived from multiple environments.

Reference this Paper: Provenance, Tectonic Setting and Source-Area Weathering of the Coastal Plain Sediments, South West, Nigeria by H.Y. Madukwe, R.A. Obasi, O.R. Fakolade, C.E. Bassey published at: "Scientific Research Journal (Scirj), Volume III, Issue II, February 2015 Edition, Page 20-31 ".

Search Terms: Felsic, weathering, chemical maturity, provenance, tectonic setting

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