Indian Ocean Pliocene Paired Foraminiferal d18O and Mg/Ca Data Karas, C.; Nürnberg, D.; Tiedemann, R.; Garbe-Schönberg, D. Karas, C. Nürnberg, D. Tiedemann, R. Garbe-Schönberg, D. earth science/paleoclimate/paleoceanography (delta 18O,Cibicidoides wuellerstorfi,null,per mil,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,Trilobatus sacculifer,null,per mil,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (magnesium/calcium,Trilobatus sacculifer,null,millimole per mole,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (age,null,null,million years ago,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,mbsf) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (ODP709C>LATITUDE -3.915>LONGITUDE 60.5517) (ODP763A>LATITUDE -20.5867>LONGITUDE 112.2083) To understand the gradual global cooling during the mid‐Pliocene (3.5-2.5 Myr ago) one needs to consider the tectonical constriction of tropical seaways, which affected ocean circulation and the evolution of climate. Here we use paired measurements of d18O and Mg/Ca ratios of planktonic foraminifera to reconstruct the Pliocene hydrography of the western tropical Indian Ocean (Site 709C) and changes in the Leeuwin Current in the eastern subtropical Indian Ocean (Site 763A) in response to Indonesian Gateway dynamics. Today, the Indonesian Throughflow (ITF) and, subsequently, the warm southward flowing Leeuwin Current off Western Australia are essential for the polar heat transport in the Indian Ocean. During 3.5-3 Ma, sea surface temperatures significantly dropped in the Leeuwin Current area, becoming since -3.3 Ma 2C-3C cooler than the rather unchanged sea surface temperatures from the eastern and western tropical Indian Ocean. We refer this drop in sea surface temperatures to a weakened Leeuwin Current with severe climatic effects on Western Australia induced by a tectonically reduced surface ITF. We suggest that this reduced surface ITF led to a diminished poleward heat transport in the Indian Ocean resulting in a weakened Leeuwin Current and possibly to cooling of the Benguela upwelling system. STUDY NOTES: Combined planktonic foraminiferal Mg/Ca and d18O data spanning the time period from 6-2 Ma, from 2 Indian Ocean ODP sites. Core ODP 763A is located in the subtropical eastern Indian Ocean within the present influence of the Leeuwin Current, and Core ODP 709C is located in the tropical western Indian Ocean. The ODP 709C isotope data are from Shackleton and Hall, 1990. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Karas, C. Investigator : Nürnberg, D. Investigator : Tiedemann, R. Investigator : Garbe-Schönberg, D. 2011-05-18 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/11195 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2011/karas2011.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2011/karas2011.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2011/karas2011.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2011/karas2011.xls English https://www.ncdc.noaa.gov/paleo/study/11195 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2011/karas2011.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2011/karas2011.xls Cyrus Karas, Dirk Nürnberg, Ralf Tiedemann, Dieter Garbe-Schönberg2011Pliocene Indonesian Throughflow and Leeuwin Current dynamics: Implications for Indian Ocean polar heat fluxPaleoceanography26210.1029/2010PA001949https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2010PA001949 START YEAR: 5994000 cal yr BP * END YEAR: 2004000 cal yr BP 60.5517 -20.5867 112.2083 -3.915