Mineralogical and Geophysical Properties of Peat Soil for Sustainable Urban Development in South Kalimantan, Indonesia

Abumbun Jaya Village, Sungai Tabuk District, South Kalimantan, is the focus of urban expansion. This land is vulnerable to settlement under loading because the topography of this area lies at an altitude of 0–10 m above sea level, with a slope of 0–2°, and is formed by alluvial deposits, sandy mud, peat, river deltas, and swamps. This study investigates the soil mineralogy of the region based on geophysical and geochemical properties as a first step towards effective and sustainable land management of two different types of peatlands: degraded and intact peatland. The geophysical properties were determined using the Wenner configuration geoelectrical method, and geochemical properties using methods such as Infrared spectroscopy, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) with Energy-Dispersive Spectroscopy (EDS) mapping. The results of the geophysical test indicate that this land is suitable for conversion because the peat thickness is less than 1.50 m, with resistivity values categorizing it into two types: first, peat with moderate to slow subsidence (20-99 Ωm), geologically interpreted as dense and dry peat with different minerals. Second, peat with minimal subsidence, suitable for light foundations (100-153 Ωm). This behavior is in line with the peat's physical properties, namely sapric peat, and its geochemical properties, which consist of O–H, C–H, C=O, C=C, C–O–C, Si–O, Al–Al–OH, Si–O–Al, and Fe–O functional groups, classifying it as mineral-rich peat that helps maintain soil stability. These scientific findings support urban development planning on peatlands and sustainable land management in peat-rich areas of South Kalimantan.