Seasonal variations of textural and heavy minerals of the Karamana river sediments and beach sediments of Trivandrum, Southern Kerala

Abstract

Kerala, a southwestern state of India, is known for its abundant heavy mineral deposits along the coast. Beach placer deposits in Kerala are known for containing ilmenite, rutile, zircon, monazite, sillimanite, and garnet. The grain size study of the sediments from the Karamana river, flowing in the southern part of Kerala, was conducted. Sediments from different parts of the river basin were studied, which enabled the understanding of grain size variations along the course of the river from the Peppara dam to Thiruvallam, very near the coast. The mineralogy of the river varies from one place to another depending on different factors such as host rocks in the province, climate conditions of the area, agents of transport, and hydraulic condition during deposition. This can also predict the actual source area associated with heavy minerals. Textural and heavy mineral studies of the placers of the beach and Karamana river basins indicate that the river is one of the important contributors of sediments to the western coast of the southern part of Kerala. Samples from various parts of the river indicate that the sediment is medium sand, moderately sorted, fine skewed, and platykurtic. The characteristics of grain size distribution are related to the source rocks, process of weathering, and different sorting processes during transportation and deposition. The total heavy mineral percentage shows it is prominently enriched in fine sand and very fine sands.