Revisiting the Geomorphology, Texture, and Mineralogy of Red Sediments from Visakhapatnam’s Coast: A Novel Perspective on Their Origin

ABSTRACT

Mokka, J.R. and K.S.S., M. 0000. Revisiting the geomorphology, texture, and mineralogy of red sediments from Visakhapatnam’s coast: A novel perspective on their origin.

This study revisits the geomorphology, texture, and mineralogy of the red sediments along the Visakhapatnam coast, presenting a novel perspective on their origin and depositional history. These sediments, characterized by their distinctive reddish hue and unique depositional features, display mineralogical and textural similarity with a combination of modern beach sands, dune sands, and shelf sediments. Quartz dominates the mineral composition portion of sand (65%) alongside heavy minerals such as sillimanite, garnet, zircon, and opaque phases, suggesting contributions from high-grade metamorphic source rocks and extensive weathering processes. The clay and silt portion accounts to 35% with clay mineral composition equivalent to present-day shelf sediments with abundant kaolinite, followed by illite and montimorillonite. These attain their reddish color due to postdepositional leaching and oxidation of certain unstable minerals such as garnets. Textural analyses reveal moderate sorting, positive skewness, and leptokurtic distributions, indicative of medium- to fine-grained sands deposited under variable energy conditions. These properties, coupled with sedimentary structures and mineral sorting patterns, strongly suggest deposition influenced by past high-energy events. Geomorphological evidence and sedimentological signatures corroborate a tsunami event in the Holocene as a significant contributor to the formation and distribution of these deposits. The episodic nature of tsunami waves facilitated the entrainment and deposition of sediments from coastal and offshore sources, resulting in the observed mixed provenance. By integrating detailed field, mineralogical, and textural data with spatial mapping and comparative analyses of analogous coastal sediments, this study refines the understanding of the genesis and paleo-environmental significance of Visakhapatnam’s red sediments. These findings underscore the interplay of marine, aeolian, and tsunami-driven processes, providing critical insights into coastal sedimentary dynamics and Holocene coastal evolution.