50,000-year-old magnetofossil

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Source-This post on 50,000-year-old magnetofossil is based on the article Goa scientists find 50,000-year-old magnetic fossils in Bay of Bengal” published in “The Hindu” on 26th March 2024.

Why in the News?

Recently, scientists have found 50,000-year-old magnetic fossils in the Bay of Bengal. It is one of the youngest giant magnetofossils to be found yet.

About the magneto fossil

Magentofossils
Source: The Hindu

Needle, spindle, bullet and spearhead shape-magnetofossils.Needle, spindle, bullet and spearhead shape-magnetofossils.Needle, spindle, bullet and spearhead shape-magnetofossils.

1. About: Magnetofossils are the fossilised remains of magnetic particles.

They are created by magnetotactic bacteria, also known as magnetobacteria.

2. Magnetotactic bacteria are mostly prokaryotic organisms that arrange themselves along the earth’s magnetic field. These unique creatures were first described in 1963.

3. These organisms were believed to follow the magnetic field to reach places that had optimal oxygen concentration.

4. It was found that the bacteria contained novel structured particles in small sacs that essentially worked as a compass. They are rich in iron.

5. These magnetotactic bacteria create tiny crystals made of the iron-rich minerals magnetite or greigite. The crystals help them navigate the changing oxygen levels in the water body in which they live.

6. The fossils left behind by the crystal-creating bacteria help scientists collect information regarding the conditions that prevailed millions of years ago, and which contributed to “the sediment magnetic signal”

Findings of the study

1. The sediment core from the southwestern Bay of Bengal consisted mainly of pale green silty clays.

2. There is presence of ‘conventional’ magnetofossils along with giant ones.

3. At a depth of around 1,000-1,500 m, the Bay of Bengal has a distinctively low oxygen concentration.

4. The rivers Godavari, Mahanadi, Ganga-Brahmaputra, Cauvery, and Penner played a crucial role in the formation of the magnetofossils.

5. Nutrient-rich sediments from rivers introduced reactive iron to the Bay of Bengal along with organic carbon in low-oxygen conditions, which supported growth of magnetotactic bacteria.

6. The freshwater discharge from these rivers along with the other oceanographic processes, like eddy formation, provided the oxygen content in these waters that isn’t usually found in other low-oxygen zones.

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