Context:
In the depths of the Bay of Bengal, scientists have discovered a 50,000-year-old sediment — a giant magnetofossil and one of the youngest to be found yet.
Relevance:
Facts for Prelims
Dimensions of the Article:
- About Magnetofossils
- Study Findings on Magnetofossils
About Magnetofossils
Definition:
- Magnetofossils are fossilised remnants of magnetic particles produced by magnetotactic bacteria, also known as magnetobacteria.
- These fossilised remains are found preserved within geological records.
Magnetotactic Bacteria:
- Characteristics:
- Magnetotactic bacteria are primarily prokaryotic organisms.
- They align themselves along Earth’s magnetic field.
- These bacteria were thought to utilize the magnetic field to navigate towards areas with optimal oxygen concentrations.
- They possess unique structured particles rich in iron, housed in small sacs that function as a compass for navigation.
- The bacteria produce tiny crystals composed of iron-rich minerals like magnetite or greigite, aiding them in navigating fluctuating oxygen levels in their aquatic habitats.
Study Findings on Magnetofossils
Sediment Core Analysis:
- A three-metre-long sediment core from the southwestern Bay of Bengal was predominantly composed of “pale green silty clays.”
Organism Presence:
- Abundant benthic and planktic foraminifera (single-celled shell-bearing organisms) were found, both near the seabed and free-floating.
Magnetofossil Identification:
- Microscopic analysis confirmed the presence of both ‘conventional’ magnetofossils and unusually large ones.
Oxygen Concentration:
- At depths between 1,000-1,500 meters, the Bay of Bengal displayed a notably low oxygen concentration.
Monsoon Fluctuations:
- Sediment sample analysis revealed fluctuations in the monsoon, evidenced by magnetic mineral particles from two distinct geological periods.
River Influence:
- Rivers like Godavari, Mahanadi, Ganga-Brahmaputra, Cauvery, and Penner, which discharge into the Bay of Bengal, were instrumental in magnetofossil formation.
- The nutrient-rich sediment carried by these rivers supplied ample reactive iron.
- This iron combined with available organic carbon in the suboxic (low oxygen) conditions of the Bay of Bengal, creating an environment conducive to magnetotactic bacteria growth.
Unique Oxygen Conditions:
- Freshwater discharge from these rivers, coupled with oceanographic processes like eddy formation, led to unique oxygen conditions not typically observed in other low-oxygen zones.
Persistence of Suboxic Conditions:
- The presence of magnetofossils indicated that the suboxic conditions in the Bay of Bengal persisted over an extended period, facilitating the sustained growth and activity of magnetotactic bacteria.
-Source: Indian Express
