Model Answer
0 min readIntroduction
The Tertiary period (66 to 2.6 million years ago) witnessed significant geological activity in India, resulting in the formation of sedimentary and volcanic rocks across various regions. These Tertiary formations are crucial hosts for several economically important mineral deposits. The Indo-Gangetic Plain, parts of the Himalayas, and the coastal regions are particularly rich in these resources. Understanding the association between Tertiary rocks and mineral deposits is vital for resource management and economic planning. This answer will briefly describe the key economic mineral deposits associated with these rocks, focusing on their occurrence and significance.
Economic Mineral Deposits in Tertiary Rocks of India
Tertiary rocks in India are broadly classified into Lower, Middle, and Upper Tertiary formations, each exhibiting varying mineral potential. The deposits are primarily sedimentary and volcanically derived.
1. Coal
Significant coal deposits are found in the Tertiary formations of North-Eastern India, particularly in Assam, Meghalaya, and Nagaland. These coals are typically lignite to bituminous in rank and are associated with the Numaligarh and Kopili formations. The Tertiary coalfields contribute substantially to the energy needs of the region.
2. Petroleum and Natural Gas
The most prominent economic mineral associated with Tertiary rocks is petroleum and natural gas. The Assam-Arakan basin, a foreland basin formed during the Tertiary period, is a major oil-producing region. Oil and gas are found in sandstones and shales of Oligocene and Miocene age. Major fields include Digboi, Naharkatiya, and Moran in Assam. The Krishna-Godavari basin also contains significant Tertiary oil and gas reserves.
3. Lignite
Lignite deposits are found in the Neyveli lignite fields in Tamil Nadu, associated with the Cuddalore Sandstone formation of the Miocene epoch. These lignite deposits are a crucial source of energy for power generation in South India.
4. Gypsum and Limestone
Tertiary sedimentary formations, particularly in Rajasthan and Gujarat, contain substantial gypsum and limestone deposits. These are used in cement production, fertilizer manufacturing, and other industrial applications. The gypsum deposits are often found as evaporites in lacustrine environments.
5. Iron Ore (Lateritic)
Lateritic iron ore deposits, formed due to weathering of basaltic rocks during the Tertiary period, are found in the Konkan coast of Maharashtra, Goa, and Karnataka. These deposits are relatively low in grade but are important for local iron and steel industries.
6. Bauxite
Bauxite, the primary ore of aluminum, is found in the Tertiary sediments of the Western Ghats and Eastern Ghats. These deposits are formed by the intense weathering of aluminum-rich rocks under tropical conditions.
7. Silica Sand
Tertiary sandstones provide a source of high-quality silica sand, used in glass manufacturing and other industries. These deposits are found in various parts of India, including Rajasthan and Gujarat.
| Mineral | Tertiary Formation | Location |
|---|---|---|
| Coal | Numaligarh, Kopili | Assam, Meghalaya, Nagaland |
| Petroleum & Natural Gas | Oligocene, Miocene | Assam-Arakan Basin, Krishna-Godavari Basin |
| Lignite | Cuddalore Sandstone | Neyveli, Tamil Nadu |
| Gypsum & Limestone | Miocene | Rajasthan, Gujarat |
| Iron Ore (Lateritic) | Tertiary Basalts | Konkan Coast (Maharashtra, Goa, Karnataka) |
Conclusion
In conclusion, Tertiary rocks of India are significant repositories of various economic mineral deposits, including coal, petroleum, lignite, gypsum, limestone, iron ore, bauxite, and silica sand. These resources play a crucial role in India’s economic development, particularly in the energy, construction, and manufacturing sectors. Further exploration and sustainable exploitation of these mineral resources are essential for ensuring long-term economic growth and energy security. Understanding the geological context of these deposits is vital for efficient resource management.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.