Early Pliocene Low Primary Productivity: Evidence from Car Nicobar Island, Northern Indian Ocean

Primary productivity is an important component of the ocean. Primary productivity data from Pliocene of northern Indian Ocean is lacking. Marine siliceous organisms viz., diatoms, radiolarians, silicoflagellates and siliceous sponges uptake dissolved silica (dSi) from the seawater. The biological uptake of dissolved silica (dSi) from the seawater and subsequent precipitation as biogenic silica (bSi) is a major biogeochemical cycle that has significant influence on productity. There is evidence of less silicified organisms based on micropalaeontological studies from early Pliocene (Zanclean) of Car Nicobar Island. The present study based on geochemical analyses (XRD and FTIR) from Sawai Bay Formation on Car Nicobar Island indicates that limited bSi is possibly the reason for low productivity during early Pliocene (Zanclean).