Relationship of Heavy Mineral Redistribution in Different Microenvironments to Seasonal Changes of Beach Processes in an Embayed Beach of Yarada-Gangavaram, North Coastal Andhra Pradesh

Along and across the east coast of India between Yarada and Gangavaram, sediment samples were collected from different microenvironments of the beach representing lower foreshore, middle foreshore, upper foreshore, berm, backshore and dune, at four stations(Yarada, Dibbavanipalem, Valametta and Gangavaram) in different monsoon seasons (NE and SW) for the period of two years (1997 to 1999). All the nucroenvironments except at Dibbavanipalem have not shown cyclic deposition and erosion with monsoons Out of Four-Size ranges +60 (+0 25 mm), +120 (-0 25 to +0 125 mm), +170 (-0 125 to +0 088 mm) and +230 (-0 088 to +0 063 mm), the -0 125 to +0 088 mm and -0 088 to +0 063 mm size range shows rich concentration of heavy minerals The heavy mineral content in the bulk sediment samples ranges from 0 53 - 48 56% in December, 1997 and 0 83 - 53 22% in December, 1998 Opaques, sillimamte, garnets, pyroxenes, amphiboles, zircons, monazite, rutile, biotite, tourmaline and apatite from the beach sands of Yarada-Gangavaram are reported Opaques are concentrated in fine fraction while garnets are concentrated in coarse fraction Scatter plots of heavy mineral assemblages and erosion/accretion indicates as the rate of erosion increases, heavy mineral concentration slightly increases in dune, backshore and foreshore Sub-Environments and the concentration of heavy minerals decreases with increase of erosion in berm sub-environment. The concentration of heavy minerals in nucroenvironments is not only related to erosion/accretion but also related to their densities Khondalite, chamokite and leptynite of the Eastern Ghats appear to be the major source for the above heavy mineral assemblages.