MAPPING OF LIMESTONE DEPOSITS IN OKELUSEARIMOGIJA FOR RESERVE ESTIMATION USING GIS-BASED TECHNIQUE

Abstract

This research focused on the mapping of Okeluse-Arimogija limestone deposit using Remote Sensing and Geographical Information System (GIS) techniques. To achieve this, satellite imagery, namely Landsat 7 and Aster were acquired from where limestone mineralization in the study area were identified and extracted. Samples were collected from the study area and analyzed to determine its grade at different locations. Spatial distribution of the major oxides’ grade was investigated using geostatistics method. From the Landsat analysis carried out, three band ratios combinations (4/2 5/3 4/3, 4/3 5/2 3/1 and 5/3 4/3 4/1) were produced. The band ratios indicate the presence of limestone as dark-reddish, molted purplish and greenish brown. The results for the major oxide composition revealed that CaO, Fe2O3, SiO2, MgO, and Al2O3 have average values of 50.14%, 1.69%, 3.35%, 1.52% and 1.11% respectively. The spatial distribution for concentration of CaO and Loss of Ignition (LOI) decreases from west to east while others oxides increases from west to east. The area of limestone was carved out using the indications from the band combinations and was determined to be 3549.731Ha using GIS geometry tool. A total of 2.3 billion tonnes was reported as limestone reserve for Okeluse-Arimogija deposit. This result shows that that the limestone in the study area is economically viable.