Magnetite: Formed in the Sea

 

Magnetite is considered the most magnetic material on earth. It is found in areas that have iron and high methane flux, particularly on the seafloor. But it isn’t exactly clear; it’s created Either by microbes that live near methane seeps or by a process that doesn’t require life.

Scientists can read magnetic records from the ancient seas. These records reveal tectonic activity, timing of earths poles, reversals, and other environmental changes of old.

Back in 2014, Zhiyong Lin And others took two sedimentary cores from the south China. This area has methane seepage from underwater formations, like gas chimneys, and mud volcanoes.

The team looked at many properties of the cores,  including genomic, magnetic, mineralogical, And geochemical. The purpose was to find the location of magnetite formation in the area.

Researchers recognized a multitude of layers of grainy, magnetite crystals containing high levels of iron. The crystals were Likely formed in an environment high in iron. Using gene sequencing, they discovered microbes such as Methanosarcina and Methanocella Inside the sedimentary layers. 

The team discovered that these unique microbes can reduce iron for energy. This reduction begins the formation of magnetite. 

Also, some sediment layers from the core were richer in pyrite, but lower in magnetite. This suggests previous activity from methane oxidizing microbes.

Findings were published in the journal of geophysical research: Solid Earth. The conclusion by scientists is magnetite found in the south China sea is likely made by microbial iron reduction, and not an abiotic process.