The Ranah Minang Silokek Geopark (RMSG) in West Sumatra is a designated Indonesian National Geopark aspiring for UNESCO Global Geopark status. This study provides a preliminary qualitative inventory of its geodiversity to evaluate its international significance, scientific value, and educational value. Based on literature synthesis and field investigations at 14 representative geosites, we characterize the lithological, stratigraphic, and geomorphological diversity. The results reveal an exceptional geological record spanning nearly 300 million years, from the Carboniferous–Permian to the Neogene. The geodiversity comprises a complete rock spectrum (sedimentary, igneous, and metamorphic), including Paleozoic limestones, Triassic granitoid intrusions, and Cenozoic sedimentary basin deposits. Geomorphological features are equally varied, encompassing extensive karst landscapes, structurally controlled fluvial systems, and tectonic landforms. This remarkable assemblage of geological features provides a coherent narrative of West Sumatra’s evolution, from its origins as part of the Gondwana, through Mesozoic tectonic amalgamation and magmatism, to Cenozoic basin development associated with the Sunda Arc subduction system. The high geodiversity of RMSG not only underscores its potential for international recognition but also offers significant opportunities for geotourism and geo-education, presenting a natural laboratory for understanding the complex geological history of Southeast Asia.

Heavy metal pollution is a major environmental concern due to the high toxicity of heavy metals in humans. High natural background radiation areas (HNBRAs) contain high concentrations of the radioactive element ²³⁸U, which decays into ²⁰⁶Pb, in their soil, crops, and water. Concentrations of the heavy metals lead (Pb) and uranium (U) are, thus, correlated with HNBRAs. Mamuju in Indonesia is a recently studied HNBRA where high concentrations of Pb and U in the soil have been reported. The present study analyzes Mamuju residents’ exposure to Pb and U. Two zones in the study area were selected for comprehensive assessment. North Botteng was chosen to represent the HNBRA, and Topoyo was selected as the control zone, with 22 urine samples collected from each zone. The samples were analyzed using a quadrupole inductively coupled plasma mass spectrometer (ICP-MS). The average concentrations of Pb measured in the urine samples were 1.31 mg L⁻¹ and 0.77 mg L⁻¹ in North Botteng and Topoyo, respectively. These values are higher than the urine Pb reference value of 5 µg L⁻¹. The urine Pb concentrations in both studied zones were alarmingly high, which may have serious health effects on the population and should warrant action to reduce Pb exposure in this area. The committed effective dose from the ingestion of ²³⁸U in North Botteng was higher than in Topoyo, measuring 36.0 mSv and 8.9 mSv, respectively. The area most affected by the ingestion of ²³⁸U was the red bone marrow, followed by the bone surface.

Granitoids in North Bangka, Bangka Belitung Province, Indonesia, are an integral part of the Southeast Asian Tin Belt magmatism, yet their deformation history from crystallization through tectonic cooling remains incompletely documented. This study characterizes the petrography and reconstructs the microstructural deformation history of granitoids. Nine representative granitoid samples were collected from outcrops at Bukit Bias, Tempilang, Siangau, Mangkol, Kelapa, Jebus, Pemali, Plangas, and Menumbing (Nikon Eclipse LV100NPOL (Nikon Corporation, Tokyo, Japan) with NIS-Elements BR software, Basic Research Version) and modal point counting (3608 points per section) were applied to ensure a more detailed description and accurate quantification of mineral compositions. The granitoids are classified as syenogranite, monzogranite, and quartz syenite based on the QAP modal diagram. The dominant minerals are K-feldspar (24.89–54.27 vol.%), quartz (16.47–37.13 vol.%), and plagioclase (10.89–24.45 vol.%), with biotite as the femic phase. Microstructural analysis reveals three successive deformation stages: (1) a suprasolidus stage (T > 650 °C) marked by submagmatic fractures, grain boundary migration (GBM) in feldspar and chessboard pattern quartz; (2) a high-temperature subsolidus stage (650–450 °C) characterized by GBM and subgrain rotation recrystallization in quartz, myrmekite, and flame perthite; and (3) a low-temperature subsolidus stage (T < 450 °C) evidenced by undulose extinction, bulging recrystallization (BLG), deformation twins in feldspar, and kink bands in feldspar and mica. The progressive microstructural sequence demonstrates that deformation was initiated during the late magmatic stage and persisted under decreasing temperature in the solid state, indicating that the North Bangka granitoids record a prolonged history of syn- to post-magmatic deformation linked to the regional tectono-magmatic evolution of the Southeast Asian Tin Belt. These granitoids belong to the Late Triassic–Early Jurassic (228–198 Ma) Klabat Granite Complex, emplaced within the Indonesian segment of the belt during the Sibumasu–Indochina collision, and the microstructural evolution documented here is consistent with this regional tectono-magmatic history.