Alteration mineral mapping to identify primary tin potential using Landsat 8 images and geographic information system in Rimba Kulit Area, Southern of Bangka Island

Abstract

Remote sensing data has been proven to provide geographic information such as geographic structures, land covers, lithologies and hydrothermal alteration minerals, as shown in previous researches. Nonetheless, in this research, Landsat 8 images as one of remote sensing images are utilized in hydrothermal alteration mineral mapping to identify primary tin which is located in Gadung village, Toboali sub-district, South Bangka District. This research is intended to identify the distribution of primary tin based on types and alteration mineralogy in the research area by using Landsat 8 images. Accordingly, the method employed in this research is defoliant method for each mineral: 4/3;2/1 band ratio for quartz identification, 4/3;6/5 band ratio for illite identification, 4/2;7/6 band ratio for chlorite identification, and 4/3;7/6 band ratio for iron oxide. Further, the observations of morphology, lithology and geological structures used 5/4;6/3;4/2 and 5/3;6/4;5/4 composite image combinations. Moreover, petrography, X-Ray Diffraction (XRD) and XRF analyses served as confirmation for the result of image interpretation. The composing lithology of the research area is generally composed of sandstone units, whereas alteration which develops is predominantly dominated by clay alteration (illite mineral) and sulphide dominance in hydrothermal solution. The primary tin mineralization developed in the research area is classified as oxide mineral characterized by the presence of wolframite, pyrite, arsenopyrite, and cassiterite, and deposited in big polymetallic veins, as well as allegedly influenced by NNW-SSE-trending main geological structure and associated to iron oxide mineral in form of goethite and hematite. Meanwhile, the type of tin mineralization developed in the research area in form of mineralization in ironstone or gossan units is the result of supergene process carried by cassiterite which associated with iron oxide minerals.