DOI: 10.6084/m9.figshare.28410452
title: Silica masses, morphological measures, and sedimentary fluxes of diatoms and radiolaria from the core RAPiD-21-3K

description: These data were produced from sediment samples taken from the kasten core RAPiD-21-3K (57°27.09’N, 27°54.53’W, 2630m) from the Gardar Drift in the subpolar North Atlantic Ocean during the RRS Charles Darwin’s cruise CD159 in 2004. Data generation took place in the Department of Earth Sciences, University of Oxford from 2022-2024. The polynomial age-model for this study was produced using four carbon-14 accelerator mass-spectrometry values from core RAPiD-21-3K, and six lead-210 values from the box core RAPiD-21-12B. The uppermost metre of the core (~800 years) was divided into 50 samples, with approximately 8-year resolution, for the quantification of silica mass in diatom frustules and radiolarian tests. 60 Coscinodiscus sp. frustules and 40 Hexacontium sp. tests per sample were isolated and their silica mass contents measured using ICP-mass spectrometry. 14 of these samples were used for size analysis, wherein 12-13 Coscinodiscus sp. frustules per sample were observed under a scanning electron microscope and their valve areas, valve diameters, valve face porosities, and mantle thicknesses were measured. The core was scanned using an ITRAX X-Ray Fluorescence core scanner at 2mm (1.6 year) resolution for flux quantification. Br and Si intensities were calibrated into weight percent Br and SiO2 and combined with the core dry-bulk density and sedimentation rate, and the latter with the measured silica mass-per-diatom frustule, to infer the flux of total organic carbon and the flux of diatoms to the sediments.Age_Model.txt - 'event' is the core, 'depth' is the distance each age measurement was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, 'error' is the measurement error in years.ICP-MS_Blanks.txt - 'event' is the core, 'sample id' is the arbitrary name of the blank run, 'Si 28 concentration' is the measured concentration of silicon-28 in each blank in µg/L.ICP-MS_Diatoms.txt - 'event' is the core, 'depth' is the midpoint distance each sediment sample was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, '# Diatoms' is the number of diatoms in each 0.5 mL sample to be measured, 'Si 28 concentration' is the measured total concentration of silicon-28 in each 0.45 mL sample aliquot in µg/L, 'blank corrected Si' is the total silicon-28 concentration minus the average blank value in µg/L, 'SiO2/diatom' is the blank corrected silicon-28 concentration scaled up from 0.45 mL to 0.5 mL, scaled from Si to SiO2, and divided by the number of diatoms per sample in ng, 'isoutlier' identifies values more than three scaled median absolute deviations from the median.ICP-MS_Radiolaria.txt - 'event' is the core, 'depth' is the midpoint distance each sediment sample was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, '# Radiolaria' is the number of radiolaria in each 0.5 mL sample to be measured, 'Si 28 concentration' is the measured total concentration of silicon-28 in each 0.45 mL sample aliquot in µg/L, 'blank corrected Si' is the total silicon-28 concentration minus the average blank value in µg/L, 'SiO2/radiolarian' is the blank corrected silicon-28 concentration scaled up from 0.45 mL to 0.5 mL, scaled from Si to SiO2, and divided by the number of radiolaria per sample in ng, 'isoutlier' identifies values more than three scaled median absolute deviations from the median.SEM_Diatoms.txt - 'event' is the core, 'depth' is the midpoint distance each sediment sample was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, 'specimen' is the arbitrary number of frustule within each sample, 'valve area' is the total area of the valve face and mantle per specimen in µg^{2}, 'mantle thickness' is the average thickness of the mantle across four points per specimen in µm, 'max/min feret's diameter' is the maximum or minimum diameter across the valve per specimen in µm.<br><br>Dry_Bulk_Density.txt - 'event' is the core, 'depth' is the midpoint distance each sediment sample was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, 'salt-corrected DBD' is the salt-corrected dry bulk density at each depth in g/cm^{3}.<br><br>XRF_Br_SiO2.txt - 'event' is the core, 'depth' is the midpoint distance each sediment sample was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, 'Br', 'SiO2' is the mass fraction of bromine or silica at each depth following calibration of the XRF-derived intensity, 'isoutlier' identifies Br or SiO2 mass fraction values more than three scaled median absolute deviations from the median.<br><br>Flux_Diatoms.txt - 'event' is the core, 'depth' is the midpoint distance each sediment sample was taken from the top of the core in cm, 'age' is the calibrated age in both years before present and in common era calendar years, 'diatom flux' is the number flux of diatom valves to the sediment per cm^{2} area per year.<br>