CORALLINE ALGAE FROM THE HUT BAY FORMATION (MIDDLE MIOCENE), LITTLE ANDAMAN, INDIA

The sediments of Hut Bay Formation (Middle Miocene), Little Andaman are characterized by coralline algae, corals and foraminifera. In the present paper, thirteen species belonging to nine genera of coralline algae are described. Out of these, one species (Harveylithon rupestris) is a new record for India. Eight species (Mesophyllum obsitum, M curium, M koritzae, M. commune, Phymatolithon calcareum, Aethesolithon problematicum, Harveylithon munitum and Sporolithon lvovicum) are first time recorded from the study area. The coralline algal assemblages can be broadly differentiated into two associations: one developed in the lower part of the studied succession deposited in deep, cool-water under low-energy conditions, and the other developed in the upper part indicating deposition in shallow, warm-water with high energy conditions. These two associations along with their growth-forms in the study area suggest that the depth, temperature, and hydrodynamic conditions might have fluctuated during deposition of the Hut Bay Formation. It seems that Lithopyllum and Phymatolithon flourished in relatively cool water environment, while Sporolithon, Harveylithon, Lithoporella, and Aetesolithon might have dominated during the warmer interval.