Early Neogene Calcareous Nannofossil Biostratigraphy of Henry Lawrence Island, Ritchie's Archipelago, Andaman Sea

A rich assemblage of calcareous nannofossils containing thirty three species is recorded from the southeast coast section of Henry Lawrence Island in the Ritchie's Archipelago of Andaman Sea. The assemblage can be assigned to the Helicosphaera ampliaperta Zone (NN4) of Martini (1971) corresponding to Zone CN3 of Okada and Bukry (1980) which is of late Early Miocene to early Middle Miocene age.