Integration of SRTM and ASTER data for litho-structural and alteration mapping in Nholi area, central Tanzania

Abstract

In this study, satellite imagery was used for structural and alteration mapping in the Nholi area, central Tanzania. Structural mapping was carried out by processing and interpreting SRTM-DEM data using remote sensing and GIS techniques. Various band ratios and the Relative Absorption Band Depth (RBD) method of ASTER image were used to delineate hydrothermal alteration zones. The orientation analysis of the extracted lineaments indicates that the study area is controlled by five structural trends: NE–SW, WNW–ESE, N–S, E–W and NW–SE. The VNIR and SWIR bands of ASTER data were effective in delineating hydrothermal alteration mineral zones associated with gold mineralization. The spatial distribution of hydrothermal alteration zones was verified by field survey, microscopic studies and XRD analysis. Furthermore, the extension of alteration zones around the known gold deposit together with lineaments has led to the identification of new potential areas. Data integration shows a positive correlation between the extracted lineaments and hydrothermal alteration zones, which may indicate that the mineralization in the study area is structurally controlled. Moreover, the microscopic study of sulphide minerals revealed both syn- and post-shearing characteristics.