TITLE:
ASTER Data Processing by Discrete Wavelets Transform and Band Ratio Techniques for the Identification of Lineaments and Hydrothermal Alteration Zones in Poli, North Cameroon
AUTHORS:
Mohamadou Ahamadou, May Nome Stella, Meying Arsène
KEYWORDS:
Discrete Wavelets Transform, Band Ratio, Lineaments, Hydrothermal Alteration
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.9,
September
25,
2023
ABSTRACT: The aim of this study is to carry out hydrothermal alteration mapping and structural mapping using ASTER images in order to identify indices that could guide mining exploration work
in the Poli area and its surroundings. To achieve this, the ASTER images
were first preprocessed to correct atmospheric effects and remove vegetation influence. Secondly, a lineament mapping was
conducted by applying Discrete Wavelet Transform (DWT) algorithms to the First Principal Component Analysis (PCA1) of Visible
Near-Infrared (VNIR) and Shortwave Infrared (SWIR) bands. Lastly, band
ratio methods were applied to the VNIR, SWIR,
and Thermal Infrared (TIR) bands to determine indices of iron
oxides/hydroxides (hematite and limonite), hydroxyl-bearing minerals (chlorite,
epidote, and muscovite), and the quartz index. The results obtained showed that the lineaments were mainly
oriented NE-SW, ENE-WSW, and E-W, with
NE-SW being the most predominant direction. Concerning hydrothermal alteration, the identified indices
covered almost the entire study area
and showed a strong correlation with lithological data. Overlaying the obtained lineaments with the hydrothermal alteration indices revealed a
significant correlation between existing mining indices and those observed in
the field. Mineralized zones generally coincided with areas of high lineament
density exhibiting significant hydrothermal alteration. Based on the correlation between existing mining indices and the
results of hydrothermal and structural mapping, the results obtained can
then be used as a reference document for any mining exploration in the study
area.