Channel Bed Sediment Textural Characteristics and Heavy Mineral Distribution in the Thamirabarani River, Southern India: Implications on Depositional Environment, Provenance, Tectonics and Climate

ABSTRACT Textural characteristics of fluvial sediments are excellent proxies for deciphering: tectonic, geomorphic and climatic conditions at source‐sink and the depositional settings, prevalent environment and energy conditions and modes and medium of transport. In this paper, we have documented the textural characteristics and heavy mineral distribution in channel bed sediments ( n = 51) of the Thamirabarani River from its source to confluence, in order to understand current environmental characteristics, and to establish a baseline data for the future studies. The results show that the majority of the samples were coarse‐ to medium‐grained, and moderately sorted. The occurrences of monazite, garnet (almandine, spessartine), magnetite, zircon, tourmaline, hypersthene, kyanite, rutile, and ilmenite indicate the provenance and general lithological control over the heavy mineral distribution. Angular heavy mineral grains all through the stream, including the lower reaches of the channel, together with high fluctuations of heavy mineral (0%–30%) in addition to a perceptible decrease at the confluence, suggested ongoing exhumation of the source areas, lower sorting effect and recycling of sediments by natural and anthropogenic influences. The spatial distribution of the textural and morphological characteristics of all the sediments and the heavy mineral grains, togther with the inferences from discriminant functions and diagrams, revealed prevailing spatial heterogeneity in unroofing of catchment/provenance, dilution effects of sediment characteristics by tributaries, as well as anthropogenic pressures/land use changes. Collectively, the study implies corroboration with inferences drawn on sedimentary textural characteristics of adjacently located river basins, signifying the documented phenomena as a regional character rather than endemic to this basin.