IJSRP, Volume 5, Issue 4, April 2015 Edition [ISSN 2250-3153]
A. O. Talabi
Weathering indices of meta-igneous rocks was qualitatively employed to decipher groundwater potentiality in Ekiti-State. Five representative samples of weathered migmatite, granite and charnockite were analysed for major and trace elements using X-Ray Fluorescence Spectrometry Analytical methods. Temperature (oC), EC (µS/cm), pH and wells static water levels/depths were measured using Multi-parameter TestrTm 35 series Meter and dip meter respectively. Ruxton ratio (RR), Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW) and Plagioclase Index of Alteration (PIA) were estimated from the chemical data. The weathering indices revealed granitic terrain with average values of RR (3.04), CIA (93.14%), CIW (98.29%) and PIA (98.19%) as the most favourable for groundwater occurrence. Migmatite with average values of RR (3.61), CIA (86.51%), CIW (91.01%) and PIA (90.45%) ranked second while charnockite with mean values of RR (3.30), CIA (84.70%), CIW (88.84%) and PIA (88.25%) was least favourable. The RR values fell in the moderately weathered profile while CIA, CIW and PIA have values greater than >50% which signified intense tropical weathering. This observation agreed with existing boreholes records in the area with average yields of 105.75m3/day, 70.21m3/day and 67.16m3/day in granite, migmatite and charnockitic terrains respectively.