Petrographic and geotechnical properties of Lateritic Soils developed over different parent rocks in Ago-Iwoye area, Southwestern Nigeria

2012 ◽  
Vol 1 (4) ◽  
pp. 584-594 ◽  
Author(s):  
Bayewu O.O ◽  
Olountola M.O ◽  
Mosuro G.O ◽  
Adeniyi S.A
Keyword(s):  
Geotechnical Properties ◽  
Southwestern Nigeria ◽  
Lateritic Soils ◽  
Parent Rocks

scholarly journals Mineralogical and Geochemical Trends in the Residual Soils above Basement Rocks in Ore Area, Southwestern Nigeria

2017 ◽  
Vol 9 (3) ◽  
pp. 42
Author(s):  
Adewole John Adeola ◽  
Emmanuel Tamunobelema Tubonemi
Keyword(s):  
Inductively Coupled Plasma ◽  
Soil Layer ◽  
Clay Mineralogy ◽  
Lateritic Soil ◽  
Residual Soils ◽  
Southwestern Nigeria ◽  
Thin Sections ◽  
Tropical Regions ◽  
Basement Rocks ◽  
Parent Rocks

Residual clays and laterite of economic values often occur within weathering profiles above basement rocks in tropical regions due to supergene enrichment and leaching of liable components. Previous studies in Ore area mainly on geochemistry of the basement rocks with scanty information on the weathered profiles. This study was carried out to determine the compositional characteristics of the basement rocks, the geochemical trends within the profiles above the parent rocks and the evaluation of their economic potentials.Petrographic study was carried out on thin sections of the rock samples. Elemental compositions of the rocks, clay, laterite, and top-soil were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Clay mineralogy was determined using X-ray Diffraction (XRD) analysis. Chemical index of Alterations (CIA) was calculated from geochemical data.Weathering of granite and banded gneiss in Ore resulted in the formation of soil layer, which ranged 0-0.5m, laterite 1.2-3m and clayey zone 2.9-3.0m. Quartz, plagioclase feldspars, microcline, biotite and hornblende were the essential minerals in the parent rocks. Granite and banded gneiss is high SiO2 (>65%) but low in MgO (<2.0%) and CaO (<4.0%). Kaolinite (60-80%), goethite (3-12%) and microcline (4-10%) were the dominant minerals in the XRD of the weathering profiles. Traces of illite were present only in granite. The CIA was generally > 85 indicating advanced state of weathering producing lateritic soil. The lateritic profiles over granite and banded gneiss of Ore area varied with the composition of the parent rocks. The clay layer has economic potential for ceramics, fertilizer and structural wares.

scholarly journals Mineralogy and Geochemistry of the Weathering Profiles above the Basement Rocks in Idi- Ayunre and Akure Districts, Southwestern Nigeria

2016 ◽  
Vol 8 (2) ◽  
pp. 15
Author(s):  
Adewole John Adeola ◽  
Abisola M. Oyebola
Keyword(s):  
Soil Layer ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Southwestern Nigeria ◽  
X Ray ◽  
Porphyritic Granite ◽  
Basement Rocks ◽  
Parent Rocks ◽  
Gneiss Granite ◽  
Chemical Index Of Alteration

Idi-ayunre and Akure areas are part of the basement complex of southwestern Nigeria and are predominantly consisted of gneisses, granite and migmatite with some minor quartz veins and pegmatite. These rocks have been greatly weathered to form clay, laterite and soils.Chemical analysis were carried out on basement rocks and exposed profiles. The weathering profile was subjected to X ray diffraction (XRD) analysis to determine mineralogical compositions whereas Chemical Index of Alteration (CIA) was calculated from the elemental concentrated data.Weathering of basement rocks in Idi-Ayunre and Akure districts resulted in the formation of soil layer which ranged 0-0.4m, laterite layer 1.2-2.2m, and clayey zone 3.8-6.6m. Quartz, plagioclase, microcline, and biotite were the main minerals in parent rocks. Some of the primary minerals such as biotite and K-feldspar have been weathered to form kaolinite. Quartz, kaolinite and goethite formed the dominant minerals revealed by X-ray diffraction on decomposed granite sequences. The results from chemical analysis showed that Al and Fe have been enriched in weathering profiles of banded gneiss, migmatite gneiss and porphyritic granite whilst on the other hand Ca, Mg, Mn, Na, K, Ti were reported to be depleted.. Silica was relatively stable from basement to the topsoil in the profile. The CIA generally ranged between 80 - 99The lateritic profiles over banded gneiss, granite and porphyritic granite of Idi-Ayunre and Akure areas varied with the composition of the parent rocks. The thick clayey layers could be of great economic importance for the production of ceramics wares and for constructional purposes.

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