ASSESSING THE SOURCE OF MAGNETIZATION IN SEDIMENTS WITH ROCK MAGNETISM AND FERROMAGNETIC RESONANCE SPECTROSCOPY
Rock magnetism and ferromagnetic resonance spectroscopy (FMR) can be used to analyze the magnetic composition of sediments at a bulk level. Magnetization properties particularly serve as a means for assessing crystal size distribution. FMR provides a mechanism for surveying the distribution of internal fields within a sample, and thus of investigating the degree of homogeneity and nature of crystal arrangement and elongation within a sample, traits which are particularly characteristic of the magnetotactic bacteria. Measurements of modern and ancient sediments suggest that FMR can distinguish sediments with magnetic mineralogy dominated by magnetite produced by magnetotactic bacteria from those with magnetic mineralogy dominated by detrital input or biologically-induced mineralization.