Sediment transport and heavy mineral distribution along the Bavanapadu-Nuvvalarevu shelf, East Coast of India: Implications for coastal Morphodynamics

Abstract

Offshore sediment transport and mineral dispersal remain less understood compared to coastal settings, despite their importance for geological and resource studies. Unlike previous studies that focused primarily on coastal sediment transport, our research extends offshore, revealing complex interactions between riverine and marine influences. This study provides new insights into sediment transport and heavy mineral distribution along the Bavanapadu–Nuvvalarevu shelf, East Coast of India, by integrating offshore sediment core analysis. Grain-size analysis indicates a transition from medium to fine sand at the surface, with silt and clay dominating subsurface layers, suggesting fluctuating energy conditions. CM diagrams and Pejrup M-triangle plots confirm a river-dominated depositional environment with beach influences, where marine currents contribute to sediment redistribution. Total Heavy Mineral (THM) content across four depth intervals (0.00–4.00 m) shows a consistent decline with depth, with the highest concentrations (1.056–9.667 wt%) in the uppermost layer, decreasing progressively to 0.210–4.417 wt% at 3.00–4.00 m. The study also reveals that heavy mineral concentration is lowest in the coarse (-35 + 60), higher in medium (-60 + 120), and highest in the fine (-120 + 230) fractions. Heavy mineral analysis reveals a decline in concentration with depth, with magnetite, ilmenite, and garnet being most abundant in fine sand, highlighting the role of hydrodynamic sorting. These findings enhance our understanding on offshore placer mineral deposition and sediment redistribution, offering valuable implications for shoreline management and resource exploration. Understanding these dynamics is essential for sustainable coastal planning and the long-term assessment of India’s offshore mineral wealth.