Foraminifera bound nitrogen isotope values, biogenic silica mass accumulation, and abundance of Neogloboquadrina pachyderma at IODP Site 361-U1475, Agulhas Plateau, spanning the MPT (600 - 1200 ka) ...

• Main Authors: Marcks, Basia, Santos, Thiago Pereira dos, Lessa, Douglas Villela de Oliveira, Cartagena-Sierra, Alejandra, Berke, Melissa A, Starr, Aidan, Hall, Ian R, Kelly, Roger P, Robinson, Rebecca S
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2022
• Subjects: Agulhas Plateau; biogenic silica; Foraminifera-bound nitrogen isotopes; G. bulloides; G. inflata; mid-Pleistocene transition; N. pachyderma; opal; Subtropical Front; Neogloboquadrina pachyderma
• Online Access: https://dx.doi.org/10.1594/pangaea.946021; https://doi.pangaea.de/10.1594/PANGAEA.946021

Individual species were identified and 550 individuals per species were picked from the >250 µm fraction under dissecting microscope for each sample. Approximately 7 mg of picked and identified foraminifera shells were crushed between glass microscope slides and rinsed with MilliQ water. Samples were cleaned prior to δ¹⁵NFB measurement as described in Marcks et al., (2023). Once samples were clean, organic nitrogen was released into solution by acid dissolution of the foraminiferal calcite. Samples were acidified prior to measurement. Nitrate concentrations were measured by chemiluminescence on a Teledyne Instruments (Model 200E) chemiluminescence NO/NOx analyzer. δ15NFB samples, 10 nmol in size, were measured by bacterial conversion of nitrate to nitrous oxide, with measurement of the δ¹⁵N of the nitrous oxide by automated extraction and gas chromatography-isotope ratio mass spectrometry on a Thermo Delta V Plus IRMS. The potassium nitrate reference materials IAEA-N3 and USGS 34 (+4.7 ‰ and 1.8 ‰, ...