Metallogenic Epochs and Provinces

Geology is part of Earth sciences dealing with the study of Earth, flow within the ocean, and Earth’s atmosphere. The field of Geology encompasses the analysis of the composition, physical properties, structure, history of the components of Earth, and the processes of shaping them. The field of Geology that is concerned with studying earth materials having economic value is called Economic Geology.

A unit of geologic time is metallogenic epochs during which favourable conditions were met, leading to specific mineral deposit classes. Metallogenic provinces are the geographic area characterised by the preponderance of particular mineral deposits.

Geology

• Geology is part of the Earth sciences dealing with the study of Earth, flow within the ocean, and the Earth’s atmosphere
• The field of Geology encompasses the study of composition, physical properties, structure, history of the components of Earth, and the processes of shaping them
• There are many subfields of Geology focusing on various areas of geologic studies

Economic Geology

• The subfield of Geology concerned with studying earth materials having economic value is Economic Geology
• The study of metallogenic epochs and provinces comes under economic Geology

Concept of metallogenic epochs and provinces

• Studies have shown that the distribution of mineral deposits in Earth’s crust is not uniform. Instead, particular deposit classes tend to be in abundance in specific areas or regions (called metallogenic provinces) and during a certain geologic period
• A unit of geologic time is metallogenic epochs during which favourable conditions were met, leading to specific mineral deposit classes. For example, the pre-Cambrian epoch deposits of iron ore in Bihar, Odisha, and Madhya Pradesh are metallogenic epochs
• Metallogenic provinces are the geographic areas characterised by the preponderance of particular mineral deposits like gold, iron, or copper
• In brief, metallogenic epochs and metallogenic provinces can be defined respectively as those intervals of time during the history of Earth and the regions of Earth that contain more than abundant deposits of a specific type; significantly more significant than in most geologic time and zones with deposits resulting from average rates of mineralisation that occurred over Phanerozoic time

Metallogenic epochs throughout Indian history and regions

Metallogenic epochs, in simple terms, are the specific periods during which mineral deposits are formed in a higher concentration than average. It does not necessarily mean that all deposits are formed in defined metallogenic epochs. The main metallogenic epochs in India were:

• Pre-Cambrian
• Late Palaeozoic
• Late Mesozoic to Early Tertiary

Pre-Cambrian epoch

• The pre-Cambrian epoch is considered very important worldwide because of a great length of time being involved and the presence or detection of varied and large deposits of minerals
• The huge range of pre-Cambrian meta-sediments and related granitoid, gneisses, etc., are considered to have a different metallogenic history where magmatism and metallogeny are posted consolidated events are important
• The pre-Cambrian epoch is defined in India by the presence of iron ore, manganese ore, gold, copper, chromite, lead, gypsum, kyanite, sillimanite, gemstones, etc
• For example, iron ore deposits in Odisha (Mayurbhanj, Keonjhar, Sundargarh), Bihar (southern Singhbhum), Madhya Pradesh (Bastar, Durg); chromite deposits in Bihar (Singhbhum), Karnataka (Mysore, Hassan); gold deposits in Andhra Pradesh (Ramgiri, Anantapur), copper deposits in Rajasthan, Andhra Pradesh (Mailagram, Gani), etc

Upper carboniferous or late Palaeozoic epoch

• Towards the permo carboniferous or late Palaeozoic epoch, significant changes on the surface of Earth were introduced by the Hercynian movement, marked by initiating the sedimentary era and mountain building
• It is known in India by the rich coal deposits of Lower Gondwana – regions like Bokaro, Jharia, Ramgarh, Raniganj, Darjeeling, etc

Late Mesozoic to early tertiary epoch

• Dominated by fissure eruptions of the basalt lava flow (commonly known as Deccan trap), this epoch occupies an area over 50K sq. km. in Central and Western India (Himalayan Ranges, Andaman, and Nicobar Islands) with semi-precious stones (amethyst, agate, rock crystal, etc.)

Metallogenic provinces throughout Indian history

The metallogenic provinces are referred to by names of specific deposits in which the region is dominant. A few popular and important metallogenic provinces in India are:

• Gold Province contains the regions of Karnataka, Andhra Pradesh, and Tamil Nadu
• Copper Provinces contain the regions of Singhbhum, Khetri-Pur, Banera-Bhinder
• Lead Zinc Province contains the regions of Hesatu-Belbathan
• Iron Ore Provinces contain the regions of Southern Singhbhum, Keonjhar, Sundargarh, Mayurganj, Durg, Bastar, Karnataka-Goa
• Manganese Provinces contain the regions of Balaghat, Bhandara, Nagpur

Conclusion

We now know that metallogenic epochs, in simple terms, are the specific periods during which mineral deposits are formed in a higher concentration than average and that metallogenic provinces are referred to by names of particular deposits the region is dominant in.