Magnetic Fossils

Magnetic Fossils


Recently, a 50,000-year-old sediment(magneto fossil) have been discovered in the Bay of Bengal. It was done by scientists from CSIR-National Institute of Oceanography.

  • Magnetic analyses and electron microscopy was used to study sediment samples from the southwestern Bay of Bengal.


GS-1 (Physical Geography)

Key Highlights:

  • Analysis of sediment samples has revealed fluctuations in monsoon strength during the Glacial Maximum-Holocene period, which had significant impacts on weathering and sedimentation patterns.
  • According to the study, the formation of giant magneto fossils doesn’t necessarily require warming events; instead, it hinges on achieving an optimal balance of iron, organic carbon, and suboxic conditions.
  • Magneto fossils carry encoded information about past environmental conditions, such as nutrient availability, oxygen levels, and water stratification in ancient aquatic environments.
  • Rivers like the Godavari, Mahanadi, Ganga-Brahmaputra, Cauvery, and Penner, which discharge into the Bay of Bengal, played a crucial role in the formation of magneto fossils by supplying nutrient-rich sediment and reactive iron.
  • The finding of giant magneto fossils in the Bay of Bengal indicates their origin in the late Quaternary period, roughly 50,000 years ago, rendering them the most recent giant magneto fossils found so far.

What are Magento Fossils?

  • They are the fossilized remains of magnetotactic bacteria that contain magnetic minerals.
  • The majority of giant magneto fossils have been discovered in sediment layers corresponding to two specific geological epochs: the Paleocene-Eocene Thermal Maximum, occurring approximately 56 million years ago, and the Middle Eocene Climatic Optimum, around 40 million years ago. These periods are notable for experiencing significant increases in global temperatures.
  • It suggested that the magnetofossils formed only during periods of extreme warming.


Magnetotactic Bacteria:

  • Magnetotactic bacteria are responsible for the fossilised magnetic particles in geological records.
  • They are mostly prokaryotic organisms that arrange themselves along the earth’s magnetic field.
  • They track magnetic field to reach places that had optimal oxygen concentration due to the presence of iron-rich crystals within their cells.
  • They also create tiny crystals of magnetite or greigite within their cells to navigate changing oxygen levels and sediment saturation in water bodies.
  • Giant magneto fossils, which are less prevalent compared to conventional magnetic fossils, are believed to be primarily produced by eukaryotes rather than bacteria.

Facts for Prelims:

  • Prokaryotes are organisms characterized by the absence of a distinct nucleus and membrane-bound organelles. Instead, their genetic material, typically in the form of a circular DNA molecule, resides freely in the cytoplasm without being enclosed within a nuclear membrane.
  • Eukaryotes are organisms that have cells containing a well-defined nucleus enclosed within a membrane. They have a variety of membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, and a complex network of internal membranes.