TY - JOUR
T1 - Proxies for paleo-oxygenation
T2 - A downcore comparison between benthic foraminiferal surface porosity and I/Ca
AU - Lu, Wanyi
AU - Barbosa, Catia F.
AU - Rathburn, Anthony E.
AU - Xavier, Priscila da Matta
AU - Cruz, Anna P.S.
AU - Thomas, Ellen
AU - Rickaby, Rosalind E.M.
AU - Zhang, Yi Ge
AU - Lu, Zunli
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/10/1
Y1 - 2021/10/1
N2 - Benthic foraminiferal surface porosity (the mean percentage of surface area covered by pores; higher porosity: lower oxygenation) and iodine to calcium ratio (I/Ca, higher I/Ca: higher oxygenation) are both promising paleoceanographic proxies that will advance through testing in down-core studies. Here we report the first down-core comparison (~45 kyr) of these proxies for a core from the southern Brazilian margin (26°40.22′ S, 46°26.46′ W, 475 m water depth). Both proxies are most sensitive to low-O2 conditions (<50 μmol/kg), and not well-constrained at higher O2 concentrations. Porosity values are generally low (<15%) and I/Ca ranges between ~4 and ~ 6 μmol/mol throughout the core. The two proxies are overall consistent, suggesting that bottom-water oxygen concentrations at the site remained above 50 μmol/kg during the last 45 kyr. Several non-O2 factors (e.g., iodate reduction rates, water mass mixing, temperature, foraminiferal shell robustness) could influence the proxies and require further investigation.
AB - Benthic foraminiferal surface porosity (the mean percentage of surface area covered by pores; higher porosity: lower oxygenation) and iodine to calcium ratio (I/Ca, higher I/Ca: higher oxygenation) are both promising paleoceanographic proxies that will advance through testing in down-core studies. Here we report the first down-core comparison (~45 kyr) of these proxies for a core from the southern Brazilian margin (26°40.22′ S, 46°26.46′ W, 475 m water depth). Both proxies are most sensitive to low-O2 conditions (<50 μmol/kg), and not well-constrained at higher O2 concentrations. Porosity values are generally low (<15%) and I/Ca ranges between ~4 and ~ 6 μmol/mol throughout the core. The two proxies are overall consistent, suggesting that bottom-water oxygen concentrations at the site remained above 50 μmol/kg during the last 45 kyr. Several non-O2 factors (e.g., iodate reduction rates, water mass mixing, temperature, foraminiferal shell robustness) could influence the proxies and require further investigation.
KW - Benthic foraminifera
KW - Bottom water
KW - Iodine
KW - Oxygen
KW - Surface pores
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U2 - 10.1016/j.palaeo.2021.110588
DO - 10.1016/j.palaeo.2021.110588
M3 - Article
AN - SCOPUS:85112760691
SN - 0031-0182
VL - 579
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
M1 - 110588
ER -