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JPAS. 2020; 20(4): 384-398 Geochemical Characteristics of the Awe Basaltic Rocks within the Middle Benue Trough, Northcentral Nigeria.Isah Lekmang, Daspan, R.I., Dibal, H.U., Daku, S.S., Diyemak, V. B., Goyit, M. P., Ajol, F.A., Chup, A. S., Piwuna, R. M., Nimchak, R., Nimze, L. and Timothy P. Bata. Abstract | | | | The Awe basaltic rocks are located in Awe Local Government Area, Nasarawa State, part of Middle Benue Trough, North Central Nigeria. This study presents new geochemical characteristic of basalts of the Awe volcanoes within the Middle Benue Trough with a focus on their origin and evolution. The volcanic plugs which are essentially basaltic, extruded the sedimentary deposits of Asu River Group, Awe and Keana Formations. A total of fourteen (14) basaltic rock samples were analyzed for major, trace and rare earth elements using ICPMS. Major oxide trends show that the rocks are product of fractional crystallization with partial melting playing an important role in their evolution. On the TAS classification diagram, the rocks expressed narrow variation in their composition ranging from typical basalts to trachybasalt hawaiite. Further geochemical data revealed that the basalts are predominantly alkaline affiliated, emplaced within-plate intracontinental rift (extensional) setting and enriched deep mantle source reservoir. Similarly, their enrichment in Light Rare Earth Elements (LREE) relative to Heavy Rare Earth Elements (HREE) are comparable to those from EMORB and OIB, supportive of rocks derived from enriched alkaline magmatism. Also, incompatible element ratios Zr/Nb; Ba/La; La/Nb, La/Yb and Ba/Nb. Thus, the geochemistry of the Awe basalts supports a plume source origin for the rocks.
Key words: basaltic rocks, Middle Benue Trough, Awe, incompatible element, volcanic plugs.
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