Cm300 tem

Two characteristic interglacial and glacial samples (taken from 1.25 and 3.15 m, respectively) were subjected to TEM analysis to obtain information about magnetofossil size and shape distributions. Magnetic extraction was performed with a Frantz isodynamic magnetic separator and a long glass tube with a stopcock at the base^{66 (link)}. Magnetic extracts were viewed and analyzed using a Philips CM300 TEM operated at 300 kV at ANU. TEM images containing magnetofossils were acquired randomly. All magnetofossil crystals in the TEM images were counted to prevent biased BS and BH estimates.

TEM samples were prepared following ref ^{31 (link)}. About 1 cm³ of untreated sediment was mixed with distilled water, and was placed in an ultrasonic bath for ~5 min. Magnetic extraction was performed with a Frantz isodynamic magnetic separator and a long glass tube with a stopcock at the base. For extraction, the tube was filled with distilled water and was placed between the electromagnet pole pieces, which was then switched on and sediment solution was added slowly into the tube from the top. Magnetic minerals, including magnetofossil crystals, were trapped onto the tube walls, while non-magnetic materials were deposited at the bottom of the tube. This procedure was repeated to increase the amount of magnetic material on the tube wall. Finally, magnetic minerals were washed off the tube wall into a container and were purified using a strong rare-earth magnet. A TEM grid was floated on top of the solution containing the extracted magnetic materials with a rare-earth magnet suspended above the TEM grid. Magnetic extracts were viewed and analysed using a Philips CM300 TEM operated at 300 kV at the Australian National University (ANU). SEM observations were made using a Carl Zeiss UltraPlus analytical field emission SEM with an INCA ENERGY 450 energy-dispersive X-ray spectroscopy system at ANU.