Indonesian Gateway DSDP214 Pliocene Paired d18O and Mg/Ca Data Karas, C.; Nuernberg, D.; Gupta, A.K.; Tiedemann, R.; Mohan, K.; Bickert, T. Karas, C. Nuernberg, D. Gupta, A.K. Tiedemann, R. Mohan, K. Bickert, T. earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (DSDP 214>LATITUDE -11.337>LONGITUDE 88.718) The tectonically driven closure of tropical seaways during the Pliocene epoch (~5-2 million years (Myr) ago) altered ocean circulation and affected the evolution of climate. Plate tectonic reconstructions show that the main reorganization of one such seaway, the Indonesian Gateway, occurred between 4 and 3 Myr ago. Model simulations have suggested that this would have triggered a switch in the source of waters feeding the Indonesian throughflow into the Indian Ocean, from the warm salty waters of the South Pacific Ocean to the cool and relatively fresh waters of the North Pacific Ocean. Here we use paired measurements of the delta18O and Mg/Ca ratios of planktonic foraminifera to reconstruct the thermal structure of the eastern tropical Indian Ocean from 5.5 to 2 Myr ago. We find that sea surface conditions remained relatively stable throughout the interval, whereas subsurface waters freshened and cooled by about 4 °C between 3.5 and 2.95 Myr ago. We suggest that the restriction of the Indonesian Gateway led to the cooling and shoaling of the thermocline in the tropical Indian Ocean. We conclude that this tectonic reorganization contributed to the global shoaling of the thermocline recorded during the Pliocene epoch, possibly contributing to the development of the equatorial eastern Pacific cold tongue. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Karas, C. Investigator : Nuernberg, D. Investigator : Gupta, A.K. Investigator : Tiedemann, R. Investigator : Mohan, K. Investigator : Bickert, T. 2009-07-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/8454 https://www1.ncdc.noaa.gov/pub/data/paleo/paleocean/by_contributor/karas2009 https://www1.ncdc.noaa.gov/pub/data/paleo/paleocean/by_contributor/karas2009 English https://www.ncdc.noaa.gov/paleo/study/8454 https://www1.ncdc.noaa.gov/pub/data/paleo/paleocean/by_contributor/karas2009 Karas, C., D. Nürnberg, A.K. Gupta, R. Tiedemann, K. Mohan, and T. Bickert. 2009. Mid-Pliocene climate change amplified by a switch in Indonesian subsurface throughflow. Nature Geoscience, 2, 434 - 438. START YEAR: 5461000 14C yr BP * END YEAR: 2013000 14C yr BP 88.718 -11.337 88.718 -11.337