Open AccessGeochemical Trends in Weathering Profiles and Their Underlying Precambrian Basement Rocks in Akure, Southwestern Nigeria
Author(s) -
Oluwatoyin O. Akinola,
Olusola A. Ola Olorun
Publication year - 2021
Publication title -
journal of environmental and earth sciences
Language(s) - English
Resource type - Journals
ISSN - 2661-3190
DOI - 10.30564/jees.v3i2.3308
Subject(s) - weathering , migmatite , charnockite , geology , basement , geochemistry , precambrian , gneiss , parent rock , proterozoic , mineralogy , metamorphic rock , geomorphology , granulite , tectonics , archaeology , paleontology , facies , structural basin , history
Akure area in southwestern Nigeria falls within the basement complex underlain by migmatite, quartzite granite and charnockite. Geochemical features of these crystalline rocks and their overlying in-situ weathering profiles are investigated and reported. Analytical result from ICP-MS facility at the University of Malaya reveals average SiO2 content in quartzite (91.1%), granite (73.8%), migmatite (67.4%) and charnockite (58.6%) categorize the rocks as siliceous. SiO2 contents in the weathering profiles above these rocks are 61.9%, 60.2%, 52.2% and 54.6% respectively. Alumina contents in the weathering profiles overlying quartzite (23.8%), granite (19.9%), migmatite (26.3%) and charnockite (24.3%) are substantially higher than the precursor rocks. In the same order, average alkali (Na2O+K2O) contents in the profiles are 3.38%, 3.42%, 3.48% and 2.68%. Chemical features of the profiles reflect that there exists some correlation between the chemistry of crystalline basement and their in-situ weathering profiles. The residual soils contain low plastic clays with kaolinitic characteristics and compare well with other clays reported from other parts of Nigeria basement complex.