Editorial: Advances in Magnetism of Soils and Sediments

Our understanding of how rock magnetism records sedimentary and environmental processes, along with the refinement of analytical methods, has substantially improved in the last decade. In addition, there is an increasing appreciation of the strong interaction between (bio)geochemical and physical systems and their preservation in the sedimentary record. These developments hold great promise for a better comprehension of the evolution of our planet through time. In this Special Issue, we highlight some of the most significant advances to the topic of sedimentary and soil magnetism and their impact on several related domains.

The Advances in Magnetism of Soil and Sediments Special Issue focuses on identifying and assessing the impact of processes that occur throughout the entire sedimentary and soil cycle on rock magnetic, paleomagnetic, and environmental records (Figure 1). Magnetic mineral assemblages are affected by a wide range of chemical, physical and biological processes at different scales in depth and through time, and therefore are good indicators of environmental changes. In terrestrial environments (e.g., soil, sediment, speleothem), the magnetic mineralogy is dominated by detrital particles, mostly iron oxy-hydroxides and iron oxides, which are eroded and transported by wind or water. Some of these minerals are further altered by weathering and diagenetic processes at depth, related to the degradation and fermentation of the organic matter. Biological activity is responsible for the formation of authigenic minerals, either intracellularly or extracellularly, in oxic sedimentary environment. Other constituents of the magnetic assemblage can include atmospheric particles from volcanic ash and anthropogenic aerosols, and to a lesser extent extraterrestrial input. Particles from land are then transported and deposited in aqueous environments and constitute the main magnetic component in marine sediments. Eolian particles (dust), volcanic ash, biogenic magnetic particles from biomineralization, and extraterrestrial input also contribute to magnetic minerals in marine sediments. Post-depositional alteration due to burial, diagenetic processes or fluid and gas circulation, in anoxic conditions, leads to a drastic change in the magnetic mineral assemblages with the reduction of iron oxy-hydroxides and iron oxides to form iron sulfides. Because of magnetic minerals sensitivity to (bio)geochemical conditions, investigating the changes in the magnetic mineral assemblages and associated mechanisms in a diversity of environments leads to new insights on past environmental and paleoceanographic conditions.