CHARACTERISTICS OF ALTERATION AND MINERALIZATION OF PRIMARY TIN IN MEMPAYAK DISTRICT, BELITUNG TIMUR REGENCY, BELITUNG ISLAND

Abstract

Indonesia is recognized as one of the world’s foremost tin-producing countries, with the Bangka Belitung Islands constituting a principal region of both historical and ongoing tin exploitation. Tin mineralization in this area is broadly categorized into secondary (placer) and primary types, with the latter commonly associated with granitic intrusions and indicative of a magmatic-hydrothermal genesis. Comprehensive investigation of primary tin deposits is critical for delineating unexploited mineral resources and provides a scientific basis for promoting sustainable development within the tin mining sector. The Mempayak area in Belitung Timur is considered geologically prospective, with indications of mineralization linked to granitic intrusions and associated hydrothermal processes. Primary tin mineralization encountered at Mempayak, Belitung Timur, is studied aiming at deposit geology, alteration and ore mineralization characterization. Samples used for this study were collected by random mapping through soil and rock chip sampling, laboratory analysis of rock and soil samples, including X-Ray Fluorescence-Portable (XRF), X-Ray Diffraction (XRD), petrography and ore microscopy. The deposit is characterized by the discovery of granite dykes and veins in granodiorite units, which contain high-grade tin mineralization grading 2.8% in quartz-muscovite-tourmaline veins. These high-grade cassiterite mineral veins are associated with sulfide minerals, including arsenopyrite and chalcopyrite and gangue minerals such as mica, tourmaline and quartz. The orientation of these veins intersects the greisen body. Alteration in this area includes clay alteration minerals, including kaolinite, k-illite and halloysite, as well as with greisen-specific minerals such as muscovite and tourmaline. The alteration and mineralization present in the study area are influenced by geological structures that show southwest-northeast and northwest-southeast oriented deformation trends. The primary tin mineralization in Mempayak is structurally controlled and genetically linked to hydrothermal processes associated with post-intrusion granitic activity. The presence of greisen alteration zones and high-grade cassiterite-bearing veins suggests a well-developed mineralizing system with significant economic potential for further tin exploration in Belitung Timur.

Keywords: Tin, Belitung Timur, Granodiorite, Veins