A magnetic approach to unravelling the paleoenvironmental significance of nanometer-sized Fe hydroxide in NW Pacific ferromanganese deposits

Chemostratigraphic and Textural Indicators of Nucleation and Growth of Polymetallic Nodules from the Clarion-Clipperton Fracture Zone (IOM Claim Area)

“…In some nodules (3602, 3604, 3613, and, especially, 3614), we observed changes in the geochemistry (increases in the Fe and Ti contents) around 750-900 ka, which may be related to the mid-Pleistocene cooling events [81], increased Fe accumulation [82], and high bioproductivity evidenced by a barite formation. On the orbital time scales, the export production of barite is generally higher during cold periods (glacial maxima) between 4.3 and 1.1 Ma [83].…”

Nanoscale Mineralogical Characterization of Terrestrial and Extraterrestrial Samples by Transmission Electron Microscopy: A Review

“…This is an exciting research area that has already gained recognition and offers much scope for new findings. ,− For example, biomineralization involves the interaction of minerals and microorganisms and is a widespread process. In recent decades, some research has shown that magnetite produced by magnetotactic bacteria (MTB) is a natural single-domain magnetic nanocrystal that can provide useful paleo-environmental information, as its morphology is associated with the environment in which the MTB groups lived. ,,, For example, Li et al used BF-TEM, HRTEM, HAADF-STEM, and 3D visualization (tomographic reconstruction imaging) to study the chain assembly and crystal growth patterns of bullet-shaped magnetosomes (Figure ) and the relationship between bacterial phylogeny and magnetosomal magnetite morphology. ,, The establishment of the relationship between magnetosome morphology and the bacterial living environment would become an important tool for the study of various paleo-environments.…”

“…As conventional TEM uses electromagnetic lenses to focus the electron beam, magnetic materials can permanently adhere to the lenses, irreparably damaging the system. Therefore, any sample containing magnetic material must be immobilized, for example, by using an oyster grid and FIB method. , In addition, terrestrial and extraterrestrial samples are complicated, so contamination during their preparation must be minimized and can be removed by plasma cleaning. The following four methods are commonly used to prepare TEM specimens from geological samples.…”

Abyssal Manganese Nodule Recording of Global Cooling and Tibetan Plateau Uplift Impacts on Asian Aridification

“…The resultant low sedimentation rates favor formation of manganese nodules, which typically grow via concentric iron and manganese oxide/hydroxide accumulation around nuclei (e.g., Christensen et al., 1997; Hein et al., 2020; van de Flierdt et al., 2004). Despite slow growth rates (∼1–10 mm/Ma), manganese nodules are suggested to be sensitive to eolian dust variations and to bottom current evolution (e.g., Jiang et al., 2021; Jones et al., 2000; Ling et al., 2005; Liu et al., 2020). Furthermore, manganese nodules can provide viable micro‐environments for deep ocean microorganisms (Blöthe et al., 2015), as evidenced by abundant living microbial populations inside nodules (e.g., Blöthe et al., 2015; Shiraishi et al., 2016).…”

“…• A manganese nodule from the NW Pacific carries a paleoclimatic record of Asian aridification since the Late Miocene • Asian aridification impacted biogeochemical cycling and abyssal microbial activity in the NW Pacific Ocean • Major Asian aridification events at ∼8-7 Ma and ∼3.6-0 Ma may be attributed to NE Tibetan Plateau uplift and global cooling, respectively be sensitive to eolian dust variations and to bottom current evolution (e.g., Jiang et al, 2021;Jones et al, 2000;Ling et al, 2005;Liu et al, 2020). Furthermore, manganese nodules can provide viable micro-environments for deep ocean microorganisms (Blöthe et al, 2015), as evidenced by abundant living microbial populations inside nodules (e.g., Blöthe et al, 2015;Shiraishi et al, 2016).…”