Figure F10. Plots of demagnetization of natural remanent magnetization (NRM), anhysteretic remanent magnetization (ARM), and isothermal remanent magnetization (IRM) and of the acquisition of IRM for (A) Section 182-1130A-6H-5 and (B) Section 182-1130A-27X-1. The plots summarize the magnetic characteristics of these samples. The ratio of IRM:ARM in (A) is indicative of single-domain behavior and suggests a magnetotactic origin of the magnetite. In (B), the ratio of ARM:IRM has fallen substantially, indicating increased dissolution with increasing depth.