Paper Number: 2272
Multifractal Analysis for Threshold Determination in Hydrothermally Altered Images around Dutsen Danbakoshi, Northwestern Nigeria.
Amuda, A.K 1*, Andongma, W.T., 2 and Gajere, J.N. 3 and Amuda A.G 4
1 Department of Geology, Ahmadu Bello University, Zaria, Kaduna State, Nigeria. akabdulgafar@abu.edu.ng
2 KITTE Geological Consult Keffi, Nasarawa State, Nigeria.
3 Department of Geology, Nasarawa State Polytechnic, Nasarawa State, Nigeria.
4 Department of Civil Engineering, Universiti Malaysia Sarawak, Sarawak, Malaysia.
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The study area lies within the Nigerian Precambrian Basement Complex. This study is aimed at identifying highly altered zones by applying concentration-area (C-A) fractal model technique on Landsat ETM+. Multifractal analysis was used to quantify degree of alteration on satellite images processed using crosta technique. The C-A fractal model was used to establish a power law relationship between area and pixel value. A log–log plot was used to display the multifractal characteristics for clay and iron altered images and identify threshold values. Maximum and minimum threshold values obtained from fractal analysis are 1.74 and 4.01 for clay altered images and 0.607 and 3.04 for iron altered images. Delineating highly altered zones from these images reveals high clay alteration mainly in the North-Central and Eastern part of the study area. High clay alteration zones accounts for 5.89% of the study area and covered an area of 22.28km2. Areas of high iron alterations are primarily located within the South-Western and South-Eastern part of the study area. These high iron alteration zones accounts for 7.84% of the study area and accounts for 29.65km2. These highly altered zones are favorable targets for prospecting mineral deposits.
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