Distribution of Strontium in Sediments of the Minicoy Atoll, Lakshadweep

Abstract

Sr content in 67 sediment samples collected from the Minicoy reef and lagoon varies from 3960 to 7000 ppm (av. 5630 ppm). The concentration increases from the reef (c 4,000 ppm) in the north and west to the centre of the lagoon (c 7,000 ppm) while it is lower near the island. Distribution of Sr indicates an inverse relation with magnesium (r = -0.37). Sr/Ca x 1000 ratios on the reef and lagoon range from 4.9 to 8.7; being higher in the lagoon and lower on the reef. Low Sr values on the reef and higher values in the lagoon are possibly related to greater contribution of calcareous algae (calcite and rich in Mg and low in Sr) to the reef sediments. Luxuriant coral (aragonite and higher in Sr) growth and greater contribution from corals to the lagoonal sediments. Sr Ca x 1000 ratios seem to indicate that the reef is not very active while the coral knolls in the lagoon are active.