# Global Ocean Mg/Ca Concentration Data from .25 to 15.75 Mya #----------------------------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # Template Version 4.0 # Encoding: UTF-8 # NOTE: Please cite original publication, NOAA Landing Page URL, dataset and publication DOIs (where available), and date accessed when using downloaded data. # If there is no publication information, please cite investigator, study title, NOAA Landing Page URL, and date accessed. # # Description/Documentation lines begin with '#' followed by a space # Data lines have no '#' # # NOAA_Landing_Page: https://www.ncei.noaa.gov/access/paleo-search/study/36413 # Landing_Page_Description: NOAA Landing Page of this file's parent study, which includes all study metadata. # # Study_Level_JSON_Metadata: https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/json/noaa-ocean-36413.json # Study_Level_JSON_Description: JSON metadata of this data file's parent study, which includes all study metadata. # # Data_Type: Paleoceanography # # Dataset_DOI: 10.25921/dwkn-3c76 # # Science_Keywords: Other Reconstruction #--------------------------------------- # Resource_Links # # Data_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/contributions_by_author/rosenthal2021/mg-ca_rosenthal2021.txt # Data_Download_Description: NOAA Template File; Mg/Ca Data # #--------------------------------------- # Contribution_Date # Date: 2022-05-10 #--------------------------------------- # File_Last_Modified_Date # Date: 2022-05-10 #--------------------------------------- # Title # Study_Name: Global Ocean Mg/Ca Concentration Data from .25 to 15.75 Mya #--------------------------------------- # Investigators # Investigators: Rosenthal, Yair; Bova, Samantha #--------------------------------------- # Description_Notes_and_Keywords # Description: seawater Mg/Ca ratios from different proxies # Provided Keywords: seawater Mg/Ca #--------------------------------------- # Publication # Authors: Zhou, X., Rosenthal, Y., Haynes, L., Si, W., Evans, D., Huang, K.-H., Hönisch, B., and Erez, J. # Published_Date_or_Year: 2021 # Published_Title: Planktic foraminiferal Na/Ca: A potential proxy for seawater calcium concentration # Journal_Name: Geochimica et Cosmochimica Acta # Volume: 305 # Edition: # Issue: # Pages: 306-322 # Report_Number: # DOI: https://doi.org/10.1016/j.gca.2021.04.012 # Online_Resource: # Full_Citation: # Abstract: The reconstruction of seawater calcium concentration ([Ca2+]SW) in the geologic past is crucial to our understanding of biogeochemical processes and elemental cycling as linked to long-term climate change. Published [Ca2+]SW estimates for the Cenozoic differ from each other in both the direction and magnitude of the change, and are associated with large uncertainties. Here we demonstrate the potential of Na/Ca in planktic foraminifera as a new proxy for reconstructing Cenozoic variations in seawater Na/Ca. Because of the long oceanic residence time of Na+ (»50 Myr), variations in foraminiferal Na/Ca should in principle reflect changes in [Ca2+]SW. Our culture experiments on live planktic species validate the approach, showing that foraminiferal Na/Ca responds to changes in [Ca2+]SW when [Na+]SW is kept constant, consistent with previous experiments on a shallow water benthic foraminifer and on inorganic calcite. The culture study suggests that planktic Na/Ca is affected, to a small extent, by calcite saturation state (Ocalcite) but not resolvably affected by temperature or salinity. A core tops transect of the planktic foraminifer Trilobatus sacculifer shows similar decreasing trends in Na/Ca and Sr/Ca with water depth that can be associated with dissolution of the tests. The strong covariance with Sr supports the hypothesis that a dominant fraction of the Na resides in lattice positions within the calcite test. Down core planktic foraminiferal records from the Atlantic and Pacific Oceans consistently show 13–28% lower Na/Ca during the mid-Miocene than during the late Pleistocene. After considering the effects of temperature, salinity and diagenesis, we conclude that the observed down core decrease in Na/Ca primarily reflects changes in seawater calcium concentration. Using the calibrations generated from our culture experiments and core top data we reconstructed [Ca2+]SW, suggesting [Ca2+]SW in the mid-Miocene was 46 ± 22% higher than at present, and decreased toward present with a pattern resembling the Neogene climate evolution represented by the benthic d18O record. The new reconstruction of [Ca2+]SW for the past 16 Myr narrows the range suggested by other [Ca2+]SW proxies, and potentially offers a new way to generate continuous records of seawater calcium concentration at sub-million years resolution. #--------------------------------------- # Funding_Agency # Funding_Agency_Name: # Grant: #--------------------------------------- # Site_Information # Site_Name: Global Ocean Sites # Location: Global Ocean # Northernmost_Latitude: 90 # Southernmost_Latitude: -90 # Easternmost_Longitude: 180 # Westernmost_Longitude: -180 # Elevation_m: #--------------------------------------- # Data_Collection # Collection_Name: mg-ca_rosenthal2021 # First_Year: 15750000 # Last_Year: 250000 # Time_Unit: calendar year before present # Core_Length_m: # Parameter_Keywords: reconstruction; trace metals in carbonates # Notes: #--------------------------------------- # Chronology_Information # Chronology: #--------------------------------------- # Variables # PaST_Thesaurus_Download_Resource: https://www.ncei.noaa.gov/access/paleo-search/skos/past-thesaurus.rdf # PaST_Thesaurus_Download_Description: Paleoenvironmental Standard Terms (PaST) Thesaurus terms, definitions, and relationships in SKOS format. # # Data variables follow that are preceded by "##" in columns one and two. # Variables list, one per line, shortname-tab-var components: what, material, error, units, seasonality, data type, detail, method, C or N for Character or Numeric data) # ## Age age,,,million years ago,,Paleoceanography;Climate Reconstructions,,,N, ## Mg/Ca_sw magnesium/calcium,sea water,,millimole per mole,,Paleoceanography;Climate Reconstructions,,,N,Seawater [Ca] is derived from the Lowess fit of T. sacculifer Na/Ca data over the last 16 Myr (Zhou et al. 2021). Seawater [Mg] is calculated from the second order polynomial fit of fluid inclusion [Mg] data from Brennan et al. (2013). ## Mg/Ca_sw_upper magnesium/calcium,sea water,unspecified error upper bound,millimole per mole,,Paleoceanography;Climate Reconstructions,,,N,The upper and lower uncertainties of seawater Mg/Ca are calculated by Mg from fluid inclusions (Brennan et al. 2013) and Ca uncertainties of Lowess fit. ## Mg/Ca_sw_lower magnesium/calcium,sea water,unspecified error lower bound,millimole per mole,,Paleoceanography;Climate Reconstructions,,,N,The upper and lower uncertainties of seawater Mg/Ca are calculated by Mg from fluid inclusions (Brennan et al. 2013) and Ca uncertainties of Lowess fit. #------------------------ # Data: # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing_Values: NA Age Mg/Ca_sw Mg/Ca_sw_upper Mg/Ca_sw_lower 0.25 5.39 5.42 5.36 0.5 5.33 5.37 5.29 0.75 5.30 5.35 5.25 1 5.26 5.32 5.21 1.25 5.22 5.27 5.16 1.5 5.13 5.17 5.08 1.75 5.05 5.08 5.01 2 5.01 5.05 4.97 2.25 4.91 4.92 4.90 2.5 4.81 4.81 4.81 2.75 4.71 4.74 4.69 3 4.62 4.65 4.60 3.25 4.54 4.58 4.51 3.5 4.46 4.51 4.42 3.75 4.36 4.40 4.33 4 4.27 4.33 4.21 4.25 4.21 4.27 4.14 4.5 4.12 4.21 4.04 4.75 4.06 4.16 3.97 5 3.99 4.10 3.89 5.25 3.96 4.07 3.85 5.5 3.91 4.03 3.80 5.75 3.87 4.00 3.75 6 3.79 3.94 3.65 6.25 3.74 3.90 3.59 6.5 3.69 3.86 3.53 6.75 3.68 3.85 3.52 7 3.63 3.81 3.47 7.25 3.58 3.78 3.40 7.5 3.55 3.75 3.37 7.75 3.53 3.72 3.36 8 3.50 3.69 3.33 8.25 3.47 3.66 3.30 8.5 3.41 3.62 3.23 8.75 3.39 3.60 3.21 9 3.36 3.57 3.17 9.25 3.36 3.57 3.18 9.5 3.33 3.54 3.15 9.75 3.36 3.58 3.17 10 3.35 3.57 3.16 10.25 3.36 3.59 3.15 10.5 3.35 3.58 3.15 10.75 3.35 3.58 3.16 11 3.37 3.59 3.18 11.25 3.38 3.58 3.19 11.5 3.37 3.59 3.18 11.75 3.38 3.60 3.19 12 3.40 3.61 3.21 12.25 3.39 3.63 3.18 12.5 3.32 3.55 3.11 12.75 3.26 3.49 3.06 13 3.19 3.44 2.98 13.25 3.15 3.40 2.94 13.5 3.13 3.36 2.93 13.75 3.10 3.33 2.90 14 3.03 3.27 2.83 14.25 2.99 3.23 2.79 14.5 2.96 3.20 2.75 14.75 2.92 3.17 2.70 15 2.88 3.14 2.66 15.25 2.84 3.11 2.62 15.5 2.77 3.05 2.54 15.75 2.69 2.97 2.45