April 20, 2024

Lukmaan IAS

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DISCOVERY OF 50,000-YEAR-OLD MAGNETOFOSSILS IN THE BAY OF BENGAL

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TAG: GS 3: SCIENCE AND TECHNOLOGY

THE CONTEXT: Scientists at the CSIR-National Institute of Oceanography, Goa, recently unearthed a significant discovery in the Bay of Bengal—a 50,000-year-old sediment containing giant magnetofossils.

EXPLANATION:

  • This finding, published in the journal Nature in February, represents one of the youngest giant magnetofossils discovered to date.

Magnetofossils:

  • Magnetofossils are fossilized remnants of magnetic particles produced by magnetotactic bacteria, also known as magnetobacteria.
  • These bacteria align themselves along Earth’s magnetic field lines, utilizing tiny crystals of iron-rich minerals like magnetite or greigite to navigate changing oxygen levels in their aquatic environments.
  • First described in the 1960s and 1970s, magnetotactic bacteria and their fossilized remains provide insights into ancient environmental conditions.

            Needle, spindle, bullet and spearhead shape-magnetofossils

Characteristics of the Sediment

  • The sediment core retrieved from the southwestern Bay of Bengal consisted primarily of pale green silty clays.
  • High-resolution transmission electron microscopy revealed the presence of magnetofossils shaped like needles, spindles, bullets, and spearheads, alongside conventional magnetofossils.
  • The unique characteristics of this sediment core shed light on the environmental conditions prevailing in the late Quaternary period.

Implications of the Discovery

  • The discovery challenges previous assumptions about the origins of giant magnetofossils, which were often attributed to events like hyperthermal vents or comet impacts.
  • Unlike earlier finds dating back millions of years, this discovery suggests that giant magnetofossils also formed during the late Quaternary period, a mere 50,000 years ago.

Role of Environmental Factors

  • Analysis of the sediment sample indicated fluctuations in monsoon activity during the last Glacial Maximum-Holocene period, approximately 29,000 to 11,700 years ago.
  • The presence of magnetic minerals from distinct geological periods suggests the influence of rivers like the Godavari, Mahanadi, Ganga-Brahmaputra, Cauvery, and Penner, which discharge into the Bay of Bengal.

Environmental Conditions Favorable for Magnetotactic Bacteria

  • The nutrient-rich sediment carried by these rivers provided an abundant supply of reactive iron, which, combined with organic carbon in suboxic conditions, created a conducive environment for magnetotactic bacteria to thrive.
  • Additionally, freshwater discharge from rivers and oceanographic processes like eddy formation contributed to oxygenation levels conducive to bacterial growth.

National Institute of Oceanography:

  • The National Institute of Oceanography (NIO) is one of the 37 constituent laboratories of the Council of Scientific & Industrial Research (CSIR), New Delhi.
  • NIO is headquartered at Dona Paula, Goa, and has regional centres at Kochi, Mumbai and Visakhapatnam.
  • NIO was established in 1966 following the International Indian Ocean Expedition (IIOE) in the 1960s.
  • It is a multi-disciplinary oceanographic research institute. The major research areas include the four traditional branches of oceanography – biological, chemical, geological/geophysical, and physical – as well as ocean engineering, marine instrumentation and marine archaeology.

SOURCE: https://www.thehindu.com/sci-tech/science/goa-scientists-find-50000-year-old-magnetic-fossils-in-bay-of-bengal/article67993453.ece

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