Quantifying Contributions of Magnetic Inclusions Within Silicates to Marine Sediments: A Dissolution Approach to Isolating Volcanic Signals for Improved Paleoenvironmental Reconstruction

Abstract

Nano-sized magnetic minerals (NSMMs) have been studied extensively due to their capability of carrying stable remanence over billions of years (e.g., Evans et al., 1968;Tarduno et al., 2006), which makes significant contributions to the preservation of paleomagnetic and paleoenvironmental records preserving in sediments (

Holocene Paleosecular Variations Recorded by Relict Magnetic Minerals in the Anoxic Black Sea Sediments

“…The irFORC distributions of studied samples have a positive peak along the B c axis up to ∼50 mT and spreading the B i > 0 axis up to ∼30 mT, and a negative region along the B i < 0 axis. This pattern is typically found in samples bearing SD magnetite (e.g., Chang, Roberts, et al., 2016; Jiang et al., 2021). The tfFORC diagrams also show positive peaks along the B c axis (Figure 6d) which are also a key indicator of the presence of SD particles (Zhao et al., 2017).…”

“…In the magnetic extractions, magnetic inclusions hosted in silicates can be found in both SEM (Figure 3j) and TEM observations (Figure 4). In Figure 4, the EDS analyses on the silicate particle indicate peaks of Iron (Fe), Oxygen (O), and Silica (Si; Figure 4c), which is coinciding with that of magnetite inclusions (e.g., Chang, Roberts, et al., 2016; Jiang et al., 2021). In Figures 4b and 4a lattice fringe image is shown for one magnetite inclusion.…”

“…Jiang et al. (2021) show that sediments dissolved in 10 mol/L HCL solution for 24 hr can efficiently remove biogenic and unprotected magnetic phases and preserve silicate hosted magnetic inclusions. In studied Black Sea sediments, SEM images of magnetic extractions from residuals after HCL treatment indicate the survivals of hemoilmenite skeletons, Cr‐Fe spinels, and magnetic inclusions (Figure S2 in Supporting Information S1).…”

“…More detailed procedures are described by Jiang et al. (2021). The obtained residuals and untreated samples were freeze‐dried again and used for later rock magnetic measurements.…”

“…After removal of the supernatant fluid, the samples were washed with ultrapure water three times. More detailed procedures are described by Jiang et al (2021). The obtained residuals and untreated samples were freeze-dried again and used for later rock magnetic measurements.…”