Ladakh's Rock Varnish

• 27 Jul 2024

Source: PIB

Why in News?

Recently,  Magnetofossils, fossilised magnetic particles from magnetotactic bacteria, have been discovered in rock varnish layers in Ladakh.

• Rock varnish is a dark brown to black coating that covers stable, subaerially exposed rock surfaces in arid and semiarid regions.

What are the Key Highlights of the Study?

• Findings:
  • The analysis of the rock varnish samples from Ladakh revealed higher concentrations of oxidized manganese (Mn4+) and carboxylic acid functionality, indicating organic signatures.
  • These findings suggest that the rock varnish in Ladakh, a potential Martian analogue site, contains enriched concentrations of magnetic minerals likely derived from biotic sources.
    • Magnetic minerals are those that preserve a record of the Earth's magnetic field from when they formed and can be found in rocks, sediments, and soils.
• Significance:
  • The study offers valuable insights for astrobiology by demonstrating how life can thrive in extreme environments, such as Ladakh, the "cold desert of India."
  • The findings are crucial for planning future space missions by Indian Space Research Organisation (ISRO) and other space agencies, including Mars exploration, where identifying habitable environments is a primary goal.
    • Identifying biotic signatures in rock varnish helps scientists target potential biosignatures on Mars and other planets, supporting the search for extraterrestrial life
      • A biosignature is any characteristic, element, molecule, substance, or feature that can be used as evidence for past or present life.

Magentofossils

• About:
  • Magnetofossils refer to fossilised remains of magnetotactic bacteria that contain magnetic minerals.
    • Magnetotactic bacteria leave fossilised magnetic particles in geological records.
• Magnetotactic Bacteria:
  • Magnetotactic bacteria are mostly prokaryotic organisms that arrange themselves along the earth’s magnetic field. It was discovered by Salvatore Bellini in 1963.
  • These organisms follow the magnetic field to reach places that had optimal oxygen concentration. This process is facilitated by the presence of iron-rich crystals within their cells. 
    • Magnetotactic bacteria create tiny crystals of magnetite or greigite within their cells to navigate changing oxygen levels and sediment saturation in water bodies.
    • Crystals within magnetotactic bacteria are arranged in a chain configuration through magnetotaxis.
  • Rare giant magneto fossils are less common than conventional magnetic fossils, these are likely produced by eukaryotes rather than bacteria.

UPSC Civil Services Examination, Previous Year Question (PYQ)

Q. Consider the following:  (2021)

1. Bacteria
2. Fungi
3. Virus

Which of the above can be cultured in an artificial/synthetic medium?

(a) 1 and 2 only 

(b) 2 and 3 only

(c) 1 and 3 only 

(d) 1, 2 and 3

Ans: (a)

Q. Consider the following statements:   (2018)

1. The Earth’s magnetic field has reversed every few hundred thousand years.
2. When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide.
3. When living organisms originated, they modified the early atmosphere of the Earth.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Ans: (c)