Paper Publications

Impact Factor:0.0

DOI number:10.1016/j.epsl.2019.115790

Journal:Earth and Planetary Science Letters

Abstract:a b s t r a c t We build micromagnetic models to investigate the magnetic properties of biogenic magnetite – a common type of magnetic mineral that is responsible for recording a wide range of biological, geophysical and geological processes on earth. The geometry of modelled particles is based on realistic size and shape distributions from nanoscale observations. Systematic changes in microstructures of biogenic magnetite ensembles are built and their magnetic properties are calculated, which enables a quantitative and separate assessment of the effect of crystal morphology and chain structures. Although the same particle size and shape distributions are used in all calculations, simulation results document large of remanence (Bcr =∼14–81 mT), dispersion parameter (DP =∼0.1–0.5), and skewness values (S = variations in magnetic properties, i.e., wide distributions of coercivity (Bc =∼10–60 mT), coercivity observed “biogenic soft” and “biogenic hard” components on biogenic magnetite-bearing samples were ∼0.7–1.1) due to variable degree of anisotropy and magnetostatic interactions. Previously, the commonly often interpreted to reflect crystal morphologies, and that the small DP values of coercivity distributions were an indication of narrow particle size distributions. Our simulations suggest that these speculations are not always the case and that magnetosome microstructures likely exert a dominant control over their magnetic properties. Our modelling results provide a new theoretical perspective on the magnetic properties of biogenic magnetite, which is important for understanding magnetic proxy signals from magnetofossils in a wide range of environmental and geological settings, and for the search for biogenic magnetite in terrestrial rocks and in extra-terrestrial materials.

Volume:527

Page Number:115790

Translation or Not:no

Date of Publication:2019-03-12

First Author:Chang, Liao

All the Authors:Harrison, Richard J,Berndt, Thomas A