Hydrothermal Alteration Interpretation Of Landsat And Aster Data For Iron Ore Detection In The Sheini Area, North Eastern Ghana
Date
2014-10
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Journal Title
Journal ISSN
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Publisher
University of Ghana
Abstract
The Sheini Hills in the Zabzugu/Tatale area of the Northern Ghana has one of the finest iron ores in Africa. The surface of the bare area at Sheini Hills is large and vegetation is few, so the extraction of mineral anomaly alteration from LANDSAT Enhanced Thematic Mapper (ETM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data is feasible, yet most mineral exploration concepts have failed to recognize the association of mineralization with alteration zones using remote sensed data. The area is an excellent environment to experiment with remote sensing for identifying iron ore. The ore deposits have iron-rich caps or gossans with distinct reflectance spectra. The large size of the gossans and associated alteration zones will make them easily detectable with orbital remote sensing platforms, such as Landsat ETM and ASTER.
The purpose of this project is to develop the procedures and demonstrate the feasibility of using multispectral remote sensed data to identify alteration zones associated with iron ore deposition in the study area. The multispectral remotely sensing datasets that have been used in this research are comprised of the LANDSAT Enhanced Thematic Mapping (ETM+) and the Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER). In this work, several advanced image processing techniques such as color composites, band ratios, principal components analysis (PCA) and the crosta technique was applied and tested. These images were produced to highlight important areas of hydrothermal alteration associated with iron ore deposition. Iron-oxide anomaly alteration was extracted by PC 3 on TM band1, band3, band4 and band7.
The results indicated good correlation between locations of hydrothermal alteration zones observed from the satellite images with the mapped iron formations, ferricretes and mapped quartzites. In this way LANDSAT and ASTER has been proven to be a powerful tool in the initial steps of ore deposit exploration.
The images produced proved to be useful in identification, detection, and delineation of hydrothermal alterations, and lithological rock units associated with iron ore deposits in the research area of the Sheini Hills. The ASTER data was processed for alteration assemblages associated with banded iron formation deposits. The Landsat ETM+ data was processed for iron oxides and generalized clay alteration. There is a close correlation between chlorite anomalies and drainage indicating that much of the alteration is related to alluvium along river or stream valleys. Many of the larger carbonate anomalies also coincide with broad areas of alluvium. There is a better correspondence between the Landsat derived haematite/jarosite anomalies and mapped iron formations/ ferricretes.
In the present study, there were no ground data, and the validation was performed on a geological map. The results of this study are based on remote sensing interpretations. As a follow up it would be advantageous to undertake a field based structural analysis to verify/revise and further develop the structural models. Field analysis should be undertaken to verify the geometry and kinematics of the major structures identified from the satellite image interpretations
Description
Thesis (MSc)
Keywords
Hydrothermal Alteration Interpretation, Landsat, Aster Data, Iron Ore, Sheini Area, North Eastern Ghana