Blake Ridge Chemistry, Foraminifera, Stable Isotope and Radiogenic Isotope Data for the last 35,000 Years Wycech, J.; Kelly, D.C.; Marcott, S.A. Wycech, J. Kelly, D.C. Marcott, S.A. earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Foraminiferal Shell Classification: Translucent Intermediate or Opaque) earth science/paleoclimate/paleoceanography (calcium carbonate,sediment,null,percent,null,paleoceanography,null,carbon coulometry,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,null) earth science/paleoclimate/paleoceanography (manganese/calcium,Globigerinoides ruber|Orbulina universa|Trilobatus sacculifer,two standard deviations,millimole per mole,null,paleoceanography,null,inductively-coupled plasma atomic emission spectroscopy,N,null) earth science/paleoclimate/paleoceanography (weight,Trilobatus sacculifer,null,microgram,null,paleoceanography,null,null,N,250-355 µm size fraction) earth science/paleoclimate/paleoceanography (Trilobatus sacculifer,null,null,count,null,paleoceanography,null,null,N,per foraminiferal classification; >150 µm size fraction) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,N,Number of sample splits >150 µm size fraction) earth science/paleoclimate/paleoceanography (Orbulina universa,null,null,count,null,paleoceanography,null,null,N,per foraminiferal classification; >150 µm size fraction) earth science/paleoclimate/paleoceanography (total planktic foraminifers,sediment,null,count,null,paleoceanography,null,null,N,>150 µm size fraction) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Foraminifera (T. sacculifer or Polyspecific=T. sacculifer Gs. ruber O. universa) Polyspecific from >150 µm size fraction T sacculifer from 250-355 µm size fraction) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Foraminiferal Shell Classification: Translucent or Opaque) earth science/paleoclimate/paleoceanography (delta 13C,Globigerinoides ruber|Orbulina universa|Trilobatus sacculifer|carbonate,null,per mil PDB,null,paleoceanography,null,accelerator mass spectrometry,N,Foraminifera from >150 µm size fraction) earth science/paleoclimate/paleoceanography (magnesium/calcium,Globigerinoides ruber|Orbulina universa|Trilobatus sacculifer,two standard deviations,millimole per mole,null,paleoceanography,null,inductively-coupled plasma atomic emission spectroscopy,N,null) earth science/paleoclimate/paleoceanography (manganese/calcium,Globigerinoides ruber|Orbulina universa|Trilobatus sacculifer,null,millimole per mole,null,paleoceanography,null,inductively-coupled plasma atomic emission spectroscopy,N,Polyspecific from >150 µm size fraction Trilobatus sacculifer from 250-355 µm size fraction) earth science/paleoclimate/paleoceanography (depth at sample start,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,Trilobatus sacculifer,null,per mil PDB,null,paleoceanography,null,null,N,250-350 µm size fraction) earth science/paleoclimate/paleoceanography (Globigerinoides ruber,null,null,count,null,paleoceanography,null,inductively-coupled plasma atomic emission spectroscopy,N,per foraminiferal classification; >150 µm size fraction) earth science/paleoclimate/paleoceanography (delta 18O,Trilobatus sacculifer,two standard deviations,per mil PDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (planktic:benthic foraminifer,sediment,null,dimensionless,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth at sample end,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (magnesium/calcium,Globigerinoides ruber|Orbulina universa|Trilobatus sacculifer,null,millimole per mole,null,paleoceanography,null,inductively-coupled plasma atomic emission spectroscopy,N,Polyspecific from >150 µm size fraction Trilobatus sacculifer from 250-355 µm size fraction) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,N,250-355 µm size fraction) earth science/paleoclimate/paleoceanography (total benthic foraminifers,sediment,null,count,null,paleoceanography,null,null,N,>150 µm size fraction) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (CH15-00-PC9>LATITUDE 31.9282>LONGITUDE -75.7296) Radiocarbon (14C) ages obtained from planktic foraminiferal calcite are a mainstay for reconstructing ocean-climate change and carbon cycle dynamics of the past 30 thousand years, yet the effects of diagenesis on this vital chronometer are poorly constrained. Here, we address this shortcoming by comparing 14C ages and trace element ratios (Mg/Ca, Mn/Ca) of planktic foraminifera with white, opaque shells deemed well preserved by traditional standards to those with exquisitely preserved translucent shells. Results support a diagenetic mechanism as opaque shells yield 14C ages invariably older and trace element ratios consistently higher than those of translucent shells. Radiocarbon age offsets are particularly pronounced in mono-specific samples taken from stratigraphic horizons proximal to the d18O maximum marking the Last Glacial Maximum (LGM) and the subsequent deglacial. Radiocarbon-based calendar ages of translucent shells from the two intervals are congruent with the established age ranges for these climate events, whereas those of co-occurring opaque shells overestimate the LGM and deglacial by 8,000-15,000 yrs and 14,000-22,000 yrs, respectively. These results demonstrate that the use of translucent foraminifera enhances reproducibility and accuracy of 14C ages by minimizing the deleterious effects of diagenesis. This study serves as a cautionary tale since white, opaque foraminifera are common in pelagic sediments, and 14C ages derived from their ostensibly well-preserved shells can lead to discrepancies in the timing of Quaternary climate events and ocean circulation reconstructions. STUDY NOTES: Radiocarbon chronology, geochemistry, and abundance counts of foraminiferal shells for the upper 270 cm of a piston core from the Blake Ridge Provided Keywords: paleoceanography, radiocarbon, foraminifera, Quaternary, diagenesis NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Wycech, J. Investigator : Kelly, D.C. Investigator : Marcott, S.A. 2016-05-19 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/20165 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-forams.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-d18o.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-pl-ben.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-chem.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-forams.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-d18o.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-pl-ben.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-chem.txt English https://www.ncdc.noaa.gov/paleo/study/20165 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-forams.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-d18o.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-pl-ben.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/wycech2016/wycech2016-ch15-00-pc9-chem.txt Wycech, J., Kelly, D.C., and Marcott, S.2016Effects of Seafloor Diagenesis on Planktic Foraminiferal Radiocarbon AgesGeology447551-55410.1130/G37864.1 -75.7296 31.9282 -75.7296 31.9282