Журнал геологии и геофизики
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Integration of Landsat Imagery and High Resolution Aeromagnetic Data for Hydrothermal Alteration Mapping in Parts of the Middle-Benue Trough

Adikwu Stephen Onum, Ibeneme, Sabinus Ikechukwu, Okereke, Chikwendu Njoku Obioha, Young Ezenwa Okenu, Stella Chigozie Iduma Uch

The studies utilized landsat imagery and high resolution aeromagnetic data to delineate and unravel hydrothermal altered structures with mineralisation potential in parts of the Middle-Benue trough, Nigeria. The study area contained metal sulphides in the Cenomanian fractures of the Asu River Group. In the processing and analysis of the landsat-8 ETM, we used Single Band Combinations, Band Ratio and Principal Component Analysis (PCA) and reference spectra analysis method. A composite using the bands 7, 5, 2 (RGB) highlighted areas with abundant iron oxides bearing minerals, and Clay minerals, as illite, kaolinite, and montmorillonite. The major anomalous alteration are seen at Gidan Shehu, east of Wukari, Kuka, Bambam, Uzam, Agor and minor anomalous alteration at Bangalala, Akwana and Dongwan. The application of enhancement filters such as reduction to equator, Analytical Signal, First Vertical Derivative (FVD), Upward continuation and Tilt derivative indicate lithology discrimination(magnetised and demagnetised areas) that correspond to the altered mapped area in the Landsate 8 ETM . Result from the high resolution aeromagnetic also shows that the structures trend majorly NE-SW and EW with minor NW-SE trends.