Freshwater plume-like condition near the north-eastern coastal Arabian Sea during early Miocene: Evidence from the stable isotope record in the growth bands of gastropods (Turritella sp.)

The Early Miocene witnessed major tectonic, palaeoceanographic and climatological reorganizations over the Asian realm. The Himalayan and Tibetan plateau upliftment influenced monsoon intensity during this age. Contemporary high-resolution tropical hydroclimate records are limited. Here, we present an early Miocene sub-annual stable isotope record from the growth bands of well-preserved Turritella sp. from the Kachchh basin, Western India. It showed delta 13C and delta 18O variabilities from -4.83 parts per thousand to -1.80 parts per thousand and - 7.06 parts per thousand to -2.66 parts per thousand (in VPDB) respectively. Conventional oxygen isotope thermometry showed an apparent temperature seasonality from 9.3 degrees to 28.1 degrees C. A comparison of the present early Miocene delta 18O record with the modern delta 18O records in the carbonates from coastal-estuarine environments of the Indian Ocean confirmed a high freshwater influx into the NE Arabian Sea during the early Miocene, similar to the modern-day freshwater plume events observed in the coastal region.