Q.“Most of the metallic minerals in India occur in the peninsular plateau region in the old crystalline rocks.” Examine the statement.
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Start your 14-day free trial to unlock the full solution →India’s metallic minerals are overwhelmingly concentrated in the peninsular plateau because its ancient, hard crystalline rocks have hosted mineral-forming processes for billions of years, unlike the younger sedimentary rocks of the northern plains.
The statement points to a fundamental geological truth about India’s mineral wealth. The peninsular plateau — comprising the Deccan Plateau, the Central Highlands, and the northeastern extensions — is built from some of the oldest rocks on Earth, dating back to the Precambrian era. These are the Archaean gneisses and schists, the Dharwar schist belts, and the Gondwana and Deccan Trap formations. It is precisely this ancient, stable crust that has allowed metallic minerals to form and remain concentrated over immense spans of geological time.
Why does age matter? Metallic minerals such as iron ore, manganese, copper, bauxite, gold, and zinc are typically associated with igneous and metamorphic processes — volcanic activity, magma intrusion, and the intense heat and pressure that recrystallise rocks. The peninsular plateau’s crystalline basement has experienced repeated episodes of such activity. For example, the iron ore belts of Odisha-Jharkhand (like the famous Singhbhum region) lie within ancient greenstone belts where banded iron formations were deposited in Precambrian seas and later metamorphosed. Similarly, the Kolar gold fields in Karnataka are hosted in Archaean schist belts. These are not random occurrences; they are direct consequences of the region’s geological history.
The northern plains, by contrast, are built from deep alluvial sediments deposited by the Indus-Ganga-Brahmaputra river systems. These are young, unconsolidated rocks — less than a few million years old — and have never undergone the heat, pressure, or magmatic activity needed to concentrate metallic ores. You will find no significant metallic mineral deposits in the Gangetic plains.
The statement also holds true for the distribution of bauxite (the ore of aluminium). Bauxite forms through lateritisation — a process of intense chemical weathering in tropical climates — and is found on the plateau’s elevated surfaces, such as the Amarkantak plateau, the Maikal hills, and parts of the Western Ghats. Again, the old crystalline rocks provide the right parent material and the stable land surface for this process to occur over millions of years. …
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