MAGNETIC FOSSILS

MAGNETIC FOSSILS

News: Recently, scientist have discovered a massive 50,000-year-old magnetic fossil in sediment deep in the Bay of Bengal, representing one of the most recent findings of its kind. Researchers at CSIR-National Institute of Oceanography employed magnetic analysis and electron microscopy to examine a sediment sample retrieved from the southwestern Bay of Bengal.

About:
• Magnetotactic Bacteria Overview:
o Magnetotactic bacteria are predominantly prokaryotic organisms discovered by Salvatore Bellini in 1963.
o These bacteria align themselves along the Earths magnetic field to locate regions with optimal oxygen levels.
o They synthesize iron-rich crystals within their cells, typically magnetite or greigite, aiding in navigation through varying oxygen 
concentrations and sediment saturation in aquatic environments.
o Crystals are arranged in a chain configuration via magnetotaxis.
• Origin of Magnetofossils:
o Giant magnetofossils are less common than regular magnetic fossils and are likely produced by eukaryotes rather than bacteria.
o Most giant magnetofossils are found in sediments dating back to two specific geological periods: the Paleocene-Eocene Thermal Maximum (approximately 56 million years ago) and the Middle Eocene Climatic Optimum (about 40 million years ago), coinciding with periods of global temperature increase.
o This suggests that magnetofossils formed primarily during times of significant warming.
o However, recent discoveries of giant magneto fossils in the Bay of Bengal, dating to the late Quaternary period (around 50,000 years ago), challenge the assumption that these fossils exclusively form during extreme warming phases.

Key Findings: 
• Monsoon Fluctuations:
o Sediment sample analysis revealed fluctuations in monsoon strength during the period from the last Glacial Maximum to the Holocene, influencing weathering processes and sediment deposition.
• Optimal Conditions for Magnetofossil Growth:
o The study proposes that warming events are not essential for the formation of giant magnetofossils. Instead, a delicate balance of iron availability, organic carbon content, and suboxic (low oxygen) conditions plays a crucial role.
• Information Encoded by Magnetofossils:
o Magnetofossils serve as indicators of past environmental conditions, preserving information about nutrient availability, oxygenation levels, and water stratification in ancient aquatic settings.
• Contributions of Rivers to Magnetofossil Formation:
o Rivers such as the Godavari, Mahanadi, Ganga-Brahmaputra, Cauvery, and Penner, which discharge into the Bay of Bengal, contributed significantly to the formation of magneto fossils. They supplied nutrientrich sediment and reactive iron, essential for the growth and preservation of magnetofossils in marine sediments.