A Multi‐Basin Calibration of Magnetofossils as a Quantitative Proxy for Bottom Water Oxygenation
Rong Huang, Liao Chang, Shengfa Liu, Jimin Yu, Wanyi Lu, Jianghui Du, Babette A. A. Hoogakker, Masanobu Yamamoto, Keiji Horikawa, Yuhji Yamamoto, Yusuke Okazaki, Pengfei Xue, Qishun Sun, Yanting Lin, Xuefa Shi, Somkiat Khokiattiwong, Narumol KornkanitnanAbstract
Magnetofossils, produced by magnetotactic bacteria, are widespread in marine sediments and are thought to be linked to oxygen concentrations. Until recently, their applications as a quantitative proxy for bottom water oxygen (BWO) are limited due to the lack of data from modern marine environments. Here, we present a multi‐basin calibration of magnetofossil assemblages from a broad range of BWO concentrations using a large set of surface sediments. We find that both coercivity fractions and crystal morphologies of magnetofossils are linearly correlated with BWO over ∼0–230 μmol/kg. We also find that while organic carbon contents primarily control magnetofossil abundance, it only has a weak influence on magnetofossil morphologies compared to BWO. Our calibration establishes magnetofossils as a quantitative oxygenation proxy, which provides rapid, and high‐resolution reconstructions of past ocean oxygenation and associated deep‐ocean carbon storage under climate transitions.