Magnetofossil

Magnetofossils are the fossil remains of magnetic particles produced by magnetotactic bacteria (magnetobacteria) and preserved in the geologic record.

[3] Following this discovery researchers began to think of the effect of magnetotactic bacteria on the fossil record and magnetization of sedimentary layers.

These hyperthermal events, such as the Palaeocene-Eocene Thermal Maximum or the Holocene Warm Period (HWP), stimulated increased productivity in planktonic and benthic foraminifera,[6] which in turn, resulted in higher levels of sedimentation.

Using this increase in concentration, researchers can use magnetofossils as an indicator of a period of relatively high (or low) temperatures in Earth's history.

Sediment aging and dissolution or alteration of magnetite present problems with providing useful measurements as the crystals structural integrity may not be preserved.

Other methods such as transmission electron microscopy (TEM)[7] of samples from deep boreholes and ferromagnetic resonance (FMR)[8] spectroscopy are being used.

FMR spectroscopy of chains of cultured magnetotactic bacteria compared to sediment samples are being used to infer magnetofossil preservation over geological time frames.

FMR measurements of saturation isothermal remanent magnetization (SIRM) in some samples, compared with FMR and rainfall measurements taken over the past 70 years, have shown that magnetofossils can retain a record of paleorainfall variations[9] on a shorter time-scale (hundreds of years), making a very useful recent history paleoclimate indicator.

This however, does not alter the promise of better insight into the Earth's microbial ecology[9] and geomagnetic variations over a large time scale presented by magnetofossils.