Presence of biogenic magnetite in ferromanganese nodules

Abstract

Transmission electron microscopy (TEM) and rock magnetic study of ferromanganese nodule sample JC120-104B collected from Clarion-Clipperton zone (CCZ) in the eastern Pacific Ocean indicate the presence of biogenic magnetite (magnetofossils). Firstorder reversal curves (FORCs) and decomposition of isothermal remanent magnetization (IRM) curves were used as the main tool for the characterization of magnetic properties of the bulk magnetic minerals present in the sample. TEM was performed for the direct identification of biogenic magnetic minerals (magnetofossils). The nodule sample has distinctive alternating Mn and Fe-rich layers per micro-X-ray fluorescence data. While diagenetic precipitation of Mn is known for the less oxygenated environment, the presence of biogenic magnetite is also common in the environments where the supply of oxygen is limited. Moreover, the increase in magnetic properties is consistent with the increase in Mn-content, which is related to favourable conditions for Mn precipitation as well as magnetite biomineralization in oxic-suboxic transition zone. Investigations on magnetofossil fingerprints lead to a better understanding of paleoenvironmental conditions involved in the formation and growth of deep-sea ferromanganese nodules.

Diversification of Iron‐Biomineralizing Organisms During the Paleocene‐Eocene Thermal Maximum: Evidence From Quantitative Unmixing of Magnetic Signatures of Conventional and Giant Magnetofossils

“…They are less distinguishable in marine sediments, due to their broader coercivity distributions in those environments (Egli, 2004a; Ludwig et al., 2013). The biogenic soft component is usually more abundant in marine sediments (Roberts, Chang, et al., 2012) and is commonly attributed to equidimensional magnetosomes, such as those found in oligotrophic environments (Hassan et al., 2020; Jiang et al., 2020; Li, Pan, et al., 2009; Li, Wu, et al., 2012; Oda et al., 2018; Yuan et al., 2020). There is good agreement between the median field of the biogenic soft component and that of cultured MTB that produce cuboctahedral magnetite particles (Li, Pan, et al., 2009; Li, Wu, et al., 2012).…”

Spatial Patterns of Microbial Diversity, Composition and Community Structure in Fe-Mn Deposits and Associated Sediments in the Atlantic and Pacific Oceans

“…Further, we detected a relatively high abundance of ASVs in the Fe-Mn crusts and nodules associated with Fe reducers and Mn oxidizers from the Alteromonadaceae, Burkholderiaceae, and Pseudomonadaceae families. Representatives of these groups have been proposed as potential keys in forming and growing Fe-Mn crusts and nodules in the Pacific Ocean (Wu et al ., 2013; Blöthe et al ., 2015; Kato et al ., 2018; Hassan et al ., 2020).…”

Spatial patterns of microbial diversity in Fe-Mn deposits and associated sediments in the Atlantic and Pacific oceans

“…We also detected a relatively high abundance of ASVs in the Fe-Mn crusts and nodules associated with Fe reducers and Mn oxidizers from the Alteromonadaceae, Burkholderiaceae, and Pseudomonadaceae families. Representatives of these groups have been proposed as potential keys in forming and growing Fe-Mn crusts and nodules in the Pacific Ocean (Blöthe et al, 2015;Hassan et al, 2020;Kato et al, 2018;Wu et al, 2013).…”