# South Atlantic DSDP516 4 Myr Foraminifera Nd, Mg/Ca, and d18O #----------------------------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program # National Centers for Environmental Information (NCEI) #----------------------------------------------------------------------- # Template Version 3.0 # Encoding: UTF-8 # NOTE: Please cite Publication, and Online_Resource and date accessed when using these data. # If there is no publication information, please cite Investigators, Title, and Online_Resource and date accessed. # # Online_Resource: https://www.ncdc.noaa.gov/paleo/study/27750 # Description: NOAA Landing Page # Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/karas2019/karas2019nd.txt # Description: NOAA location of the template # # Original_Source_URL: # Description: # # Description/Documentation lines begin with # # Data lines have no # # # Archive: Paleoceanography # # Dataset DOI: # # Parameter_Keywords: oxygen isotopes, geochemistry, radiogenic isotopes #-------------------- # Contribution_Date # Date: 2019-09-23 #-------------------- # File_Last_Modified_Date # Date: 2019-09-23 #-------------------- # Title # Study_Name: South Atlantic DSDP516 4 Myr Foraminifera Nd, Mg/Ca, and d18O #-------------------- # Investigators # Investigators: Karas, C.; Goldstein, S.L.; deMenocal, P.B. #-------------------- # Description_Notes_and_Keywords # Description: Neodymium isotopes of Fe-Mn-oxyhydroxide encrusted foraminifera, benthic foraminiferal Mg/Ca and BWT, and stable isotopes from southwest Atlantic DSDP Site 516/516A for the past 4 million years. #-------------------- # Publication # Authors: Cyrus Karas, Steven L. Goldstein, Peter B. deMenocal # Published_Date_or_Year: 2019-11-01 # Published_Title: Evolution of Antarctic Intermediate Water during the Plio-Pleistocene and implications for global climate: Evidence from the South Atlantic # Journal_Name: Quaternary Science Reviews # Volume: 223 # Edition: 105945 # Issue: # Pages: # Report_Number: # DOI: 10.1016/j.quascirev.2019.105945 # Online_Resource: https://www.sciencedirect.com/science/article/pii/S0277379119304184 # Full_Citation: # Abstract: Formed in the Southern Ocean, Antarctic Intermediate Water (AAIW) plays a fundamental role in the modern climate system as an important sink for atmospheric CO2, and as a mid-depth conduit supplying nutrient-rich waters to subtropical and tropical upwelling regions. During the transition from warm Pliocene 'greenhouse' conditions to Pleistocene 'icehouse' conditions around 3 Ma, model simulations suggest dramatic circulation changes in the Southern Ocean AAIW formation region due to cooling and expanded sea ice cover around Antarctica. However, the history and properties of AAIW over this time period are still poorly understood. Here, we trace AAIW source water provenance, temperature, and salinity changes over the last 4 Myr using Nd isotopes of Fe-Mn-oxyhydroxide encrusted foraminifera, benthic foraminiferal Mg/Ca, and stable isotopes from southwest Atlantic DSDP Site 516. Our results show that modern AAIW properties emerged gradually over the last 3 Myr, as evidenced by gradual cooling (6C) and freshening of intermediate waters. Over this same interval, ENd-values decrease and diverge away from those of Pacific-sourced waters and converge on values of present-day Circumpolar Deep Water (CDW). These observations are in accordance with model simulations indicating increased deep vertical mixing at the Polar Front associated with sea ice extension. These modified AAIW source waters penetrated increasingly northward into the Atlantic at intermediate depths, enhancing nutrient supply and contributing to surface cooling along subtropical coastal upwelling sites. These circulation changes may have facilitated ocean CO2 storage, providing a positive feedback amplifying global cooling and intensification of Northern Hemisphere Glaciation. #------------------ # Funding_Agency # Funding_Agency_Name: German Research Foundation # Grant: KA3461/1-2 #------------------ # Funding_Agency # Funding_Agency_Name: Columbia University Center for Climate and Life # Grant: #------------------ # Funding_Agency # Funding_Agency_Name: Columbia University Department of Earth and Environmental Sciences # Grant: Storke Endowment #------------------ # Site_Information # Site_Name: DSDP 516A # Location: Ocean>Atlantic Ocean>South Atlantic Ocean # Country: # Northernmost_Latitude: -30.2833 # Southernmost_Latitude: -30.2833 # Easternmost_Longitude: -35.2833 # Westernmost_Longitude: -35.2833 # Elevation: -1313 #------------------ # Data_Collection # Collection_Name: Karas2019Nd # Earliest_Year: 4670000 # Most_Recent_Year: 70000 # Time_Unit: Cal. Year BP # Core_Length: 32.15 # Notes: #------------------ # Chronology_Information # Chronology: Based on foraminiferal, nannofossil biodatums and benthic isotope stratigraphy. For details see original publication # #---------------- # Variables # # Data variables follow are preceded by "##" in columns one and two. # Data line variables format: one per line, shortname-tab-variable components (what, material, error, units, seasonality, data type,detail, method, C or N for Character or Numeric data, free text) # ## SampleIDa sample identification,,,,,paleoceanography,,,N,Sample ID a ## SampleIDb sample identification,,,,,paleoceanography,,,C,Sample ID b ## SampleIDc sample identification,,,,,paleoceanography,,,N,Sample ID c ## SampleIDe sample identification,,,,,paleoceanography,,,N,Sample ID e ## SampleIDf sample identification,,,,,paleoceanography,,,N,Sample ID f ## depth_m depth, , , meter, ,paleoceanography,,,N, meters below sea floor ## age_Ma age,,,million years ago,,paleoceanography,,,N, ## 143Nd/144Nd 143Nd/144Nd,,,,,paleoceanography,,,N, ## 143Nd/144Nderr 143Nd/144Nd,,two standard deviations,,,paleoceanography,,,N,in-run error ## 143Nd/144Ndrepr 143Nd/144Nd,,two standard deviations,,,paleoceanography,,,N,Combined 143Nd/144Nd error and JNdi reproducibility ## eNd epsilon neodymium,,,,,paleoceanography,,,N, ## eNderr epsilon neodymium,,two standard deviations,,,paleoceanography,,,N,in-run error ## eNdrepr epsilon neodymium,,two standard deviations,,,paleoceanography,,,N,Combined eNd error and JNdi reproducibility # #---------------- # Data: # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing_Values: NaN # SampleIDa SampleIDb SampleIDc SampleIDe SampleIDf depth_m age_Ma 143Nd/144Nd 143Nd/144Nderr 143Nd/144Ndrepr eNd eNderr eNdrepr 1 H 1 25 27 0.25 0.07 0.512263 0.000016 0.000020 -7.31 0.31 0.40 1 H 2 75 77 2.25 0.53 0.512269 0.000017 0.000021 -7.20 0.33 0.42 2 H 1 75 77 3.25 0.71 0.512312 0.000015 0.000020 -6.37 0.29 0.39 2 H 2 75 77 4.75 0.98 0.512309 0.000018 0.000023 -6.41 0.36 0.44 3 H 1 25 27 7.15 1.47 0.512321 0.000016 0.000021 -6.19 0.31 0.41 3 H 2 75 77 9.15 1.87 0.512307 0.000011 0.000017 -6.45 0.21 0.34 3 H 3 25 27 10.15 2.23 0.512340 0.000015 0.000020 -5.80 0.30 0.40 4 H 1 25 27 11.55 2.91 0.512308 0.000013 0.000019 -6.39 0.26 0.37 4 H 2 25 27 13.05 3.05 0.512360 0.000005 0.000014 -5.40 0.10 0.28 4 H 3 25 27 14.55 3.19 0.512330 0.000013 0.000018 -6.00 0.25 0.36 5 H 1 75 77 16.45 3.38 0.512335 0.000012 0.000017 -5.91 0.23 0.34 5 H 2 25 27 17.45 3.47 0.512286 0.000012 0.000018 -6.87 0.23 0.35 5 H 3 75 77 19.45 3.66 0.512326 0.000012 0.000018 -6.09 0.23 0.35 6 H 1 25 27 20.35 3.71 0.512299 0.000012 0.000018 -6.60 0.24 0.35 6 H 2 75 77 22.35 3.84 0.512301 0.000025 0.000028 -6.58 0.49 0.56 6 H 3 75 77 23.85 3.97 0.512311 0.000010 0.000017 -6.38 0.20 0.33 7 H 1 25 27 24.75 4.05 0.512327 0.000014 0.000019 -6.06 0.28 0.38 7 H 2 75 77 26.75 4.22 0.512335 0.000014 0.000019 -5.91 0.28 0.38 7 H 3 25 27 27.75 4.30 0.512319 0.000013 0.000019 -6.22 0.26 0.37 8 H 2 125 127 31.65 4.63 0.512300 0.000016 0.000020 -6.60 0.31 0.40 8 H 3 25 27 32.15 4.67 0.512281 0.000013 0.000018 -6.96 0.25 0.36