Model Answer
0 min readIntroduction
A craton is a stable continental block composed of ancient crystalline rocks, typically surrounded by mobile belts. The Singhbhum Craton, located in eastern India (Jharkhand and Odisha states), is one of the oldest and most important cratons in the Indian Shield. It represents a fragment of the ancient Gondwana supercontinent and holds significant geological and economic importance due to its rich mineral resources. Understanding its stratigraphy – the layering of rocks – is fundamental to deciphering its geological evolution and predicting the location of valuable mineral deposits. This answer will detail the stratigraphy of the Singhbhum Craton, progressing from the basement rocks to the overlying sedimentary sequences, and subsequently discuss its economic significance.
Stratigraphy of Singhbhum Craton
The stratigraphy of the Singhbhum Craton can be broadly divided into the following units, arranged chronologically from oldest to youngest:
1. Basement Rocks (Archean to Proterozoic)
The basement comprises highly metamorphosed and deformed rocks representing the oldest part of the craton. These include:
- Granite-Gneiss Complex: Predominantly tonalite-trondhjemite-granodiorite (TTG) gneisses and granites, formed during the Archean eon (older than 2.5 billion years). These are the fundamental building blocks of the craton.
- Iron Formation (Early Proterozoic): Banded Iron Formations (BIFs) are crucial components of the basement, representing significant sources of iron ore. The Noamundi and Gua iron formations are prime examples.
- Dharwar Supergroup (Early Proterozoic): Consisting of volcanic and sedimentary rocks, including cherts, greywackes, and shales.
2. Proterozoic Sedimentary Sequences
Overlying the basement rocks are Proterozoic sedimentary sequences, representing periods of relative tectonic stability and basin formation.
- Iron Ore Series (Early Proterozoic): Characterized by thick sequences of banded iron formations (BIFs), shale, and dolomite. This series is the primary source of iron ore in the region. The major formations include:
- Noamundi Formation: Known for high-grade hematite iron ore.
- Gua Formation: Also rich in hematite iron ore.
- Badampahar Formation: Contains both hematite and magnetite iron ore.
- Paila Group (Middle Proterozoic): Comprises shale, sandstone, and conglomerate, indicating a transition to a more clastic sedimentary environment.
- Chaibasa Group (Late Proterozoic): A thick sequence of shale, sandstone, conglomerate, and limestone. This group is important for understanding the paleogeographic conditions during the Late Proterozoic.
- Gangpur Group (Late Proterozoic): Characterized by shale, sandstone, and iron-rich sediments.
3. Gondwana Sediments (Permian-Jurassic)
The youngest sediments are of Gondwana age, representing continental rift-related deposition.
- Talchir Formation (Permian): Characterized by coarse-grained sediments, including conglomerates and sandstones, deposited in fluvial environments.
- Barakar Formation (Permian-Triassic): Dominated by sandstones and shales, often containing coal seams.
- Mahadevi Formation (Triassic): Composed of sandstones and shales.
- Rajnagar Formation (Jurassic): Characterized by sandstones and shales.
Economic Significance
The Singhbhum Craton is renowned for its abundant mineral resources. The economic significance is primarily linked to the following:
- Iron Ore: The BIFs of the Iron Ore Series are the most significant economic resource. The Noamundi, Gua, and Badampahar mines are major producers of iron ore, contributing significantly to India's steel industry.
- Manganese: Significant deposits of manganese ore are associated with the iron formations and sedimentary sequences.
- Chromite: Chromite deposits are found in association with ultramafic rocks within the basement complex.
- Copper: Copper mineralization is associated with volcanic and sedimentary rocks of the Proterozoic sequences.
- Uranium: Uranium mineralization is found in the Proterozoic sediments, particularly in the East Singhbhum district.
- Coal: Gondwana sediments contain economically viable coal seams, contributing to energy production.
- Limestone: The Chaibasa Group contains substantial limestone deposits used in cement production.
The geological mapping and exploration efforts, aided by remote sensing and geochemical surveys, continue to reveal new mineral potential within the Singhbhum Craton.
Conclusion
The Singhbhum Craton’s stratigraphy reveals a complex geological history spanning billions of years, from Archean basement formation to Gondwana sedimentation. This layered geological record is directly responsible for the craton’s exceptional mineral wealth, particularly its iron ore deposits, which are vital to India’s economic development. Continued geological research and sustainable mining practices are crucial for maximizing the economic benefits while minimizing environmental impacts. Further exploration, utilizing advanced technologies, is likely to uncover additional mineral resources within this geologically significant region.
Answer Length
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