Model Answer
0 min readIntroduction
Copper is a vital metal for industrial development, and India possesses several significant copper deposits. Two prominent occurrences are found within the Precambrian terrains of eastern and northwestern India – the Singhbhum Shear Zone in Jharkhand and the Khetri Copper Belt in Rajasthan. These deposits are genetically linked to large-scale tectonic events and represent important examples of volcanogenic massive sulfide (VMS) and sedimentary exhalative (SEDEX) mineralization, respectively. Understanding their geological settings is crucial for resource assessment and sustainable exploitation.
Geological Setting of Singhbhum Shear Zone Copper Deposits
The Singhbhum Shear Zone (SSZ) is a Proterozoic (approximately 1.8-1.6 Ga) crustal-scale shear zone extending for over 250 km in eastern India. It represents a major suture zone between the Chotanagpur Gneissic Complex (CGNC) and the younger sedimentary sequences of the Pranhita-Godavari Valley.
- Tectonic Setting: The SSZ formed due to transcurrent movements along a major fault system during the assembly of the Indian continent. This shearing created pathways for hydrothermal fluids.
- Rock Types: Predominantly Archaean gneisses, granites, and schists of the CGNC, along with Proterozoic metasedimentary rocks (quartzites, conglomerates, shales).
- Mineralization: Copper mineralization occurs as stratiform and stratabound deposits, primarily as chalcopyrite, pyrite, and pyrrhotite, associated with banded iron formations (BIFs) and volcanogenic rocks. The deposits are considered volcanogenic massive sulfide (VMS) type.
- Ore Characteristics: Disseminated and massive sulfide ores, often containing gold and silver as by-products.
- Examples: Key deposits include Surda, Kendadih, and Badia.
Geological Setting of Khetri Copper Belt
The Khetri Copper Belt is located in the Delhi Supergroup of Rajasthan, representing a Neoproterozoic (approximately 850-750 Ma) sedimentary basin. It extends for about 300 km in a north-south direction.
- Tectonic Setting: The Khetri Belt formed in a rifted continental margin setting associated with the breakup of the Rodinia supercontinent. This rifting created a basin for sedimentary accumulation and volcanic activity.
- Rock Types: Predominantly sedimentary rocks of the Delhi Supergroup, including quartzites, shales, and limestones, interbedded with volcanic rocks (basalts, rhyolites).
- Mineralization: Copper mineralization occurs as stratiform and stratabound deposits, primarily as chalcopyrite, bornite, and chalcocite, associated with black shales and volcanic horizons. The deposits are considered sedimentary exhalative (SEDEX) type.
- Ore Characteristics: Layered sulfide ores, often enriched in zinc and lead, with significant silver content.
- Examples: Key deposits include Khetri, Singhana, and Balia.
Comparative Analysis
| Feature | Singhbhum Shear Zone | Khetri Copper Belt |
|---|---|---|
| Age | Proterozoic (1.8-1.6 Ga) | Neoproterozoic (850-750 Ma) |
| Tectonic Setting | Transcurrent Shear Zone | Rifted Continental Margin |
| Dominant Rock Type | Archaean Gneisses & Proterozoic Metasediments | Delhi Supergroup Sediments & Volcanics |
| Mineralization Type | VMS (Volcanogenic Massive Sulfide) | SEDEX (Sedimentary Exhalative) |
| Major Copper Mineral | Chalcopyrite, Pyrite, Pyrrhotite | Chalcopyrite, Bornite, Chalcocite |
Conclusion
Both the Singhbhum Shear Zone and the Khetri Copper Belt represent significant copper resources in India, formed in distinct geological settings and through different mineralization processes. The SSZ’s VMS deposits are linked to Archaean crustal reworking, while the Khetri Belt’s SEDEX deposits are associated with Neoproterozoic rifting. Further exploration and understanding of the geological controls on mineralization in these regions are crucial for sustainable copper production and contributing to India’s economic growth.
Answer Length
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