Mineralogical and textural characterization of salt pan core sediments using X-ray diffraction from the south coast of India

Core sediments from the Mahabalipuram Salt Pan (SAP) were analyzed to determine grain size distribution, calcium carbonate (CaCO₃) content, organic matter, and mineral composition using X-ray diffraction (XRD). Grain size analysis shows that sand dominates the upper layers (approximately 65–80%), while finer fractions increase with depth, indicating shifts in sediment transport mechanisms and hydrodynamic conditions. Organic matter content decreases with depth, from 3.8% at the surface to 0.9% in deeper layers, reflecting changes in biological productivity and post-depositional processes. CaCO₃ concentrations range from 1.0% to 9.5%, suggesting periodic changes in salinity and marine influence. XRD results identify quartz (55–68%) as the dominant mineral, followed by feldspar (10–15%), goethite (4–8%), augite (2–5%), and trace amounts of hubnerite, indicating both terrestrial and marine sediment sources. The increasing clay and iron-rich minerals (up to 10%) in deeper layers suggest prolonged oxidative conditions and diagenetic alteration. These results provide insights into past climate variability, hydrological changes, and sedimentary dynamics in a coastal salt pan environment. The integrated sedimentological and geochemical data serve as a foundation for understanding depositional processes and support sustainable development and conservation efforts.