Alluvial placer garnet deposits of Vaippar basin, southern Tamil Nadu, India: Origin, distribution, geomorphological control and resource evaluation

The occurrence of workable beach placer deposits of garnet and ilmenite along the coastal region of southern Tamil Nadu is known for long. Though the adjoining rivers like Kallar, Vaippar and Vembar are generally thought to be the major contributors of placer minerals, especially garnet, to their respective beaches, none of the river basins has yet been explored. The present paper discusses the distribution, resource potential and geomorphic controls of garnet placer in the Vaippar basin using ArcGIS. Analysis of sediment samples collected from the Vaippar River and its tributaries shows that the concentration of garnet is up to 20 wt.% and predominantly localized in river alluvium, coastal alluvium and pediment. A distribution map of garnet for the entire basin (5508 km(2)) portrays three zones of enrichment: zone I: 0.06-1.0 million tonnes (Mt); zone II: 1.0-1.1 Mt; zone III: 1.1-1.21 Mt. It is estimated that in zone III (942 km(2)) for every 100 km(2), about 17 km(2) area has an average garnet reserve of 1 Mt and this could be profitably mined.