Abstract

AbstractCarbonatites are carbonate-rich rocks of igneous origin. They form the magmas of their own that are generated in the deep mantle by low degrees of partial melting of carbonated peridotite or eclogite source rocks. They are known to occur since the Archaean times till recent, the activity showing gradual increase from older to younger times. They are commonly associated with alkaline rocks and be genetically related with them. They often induce metasomatic alteration in the country rocks forming an aureole of fenitization around them. They are host for economically important mineral deposits including rare metals and REE. They are commonly associated with the continental rifts, but are also common in the orogenic belts; but not known to occur in the intra-plate regions. The carbonatites are known to occur all over the globe, majority of the occurrences located in Africa, Fenno-Scandinavia, Karelian-Kola, Mongolia, China, Australia, South America and India. In the Indian Subcontinent carbonatites occur in India, Pakistan, Afghanistan and Sri Lanka; but so far not known to occur in Nepal, Bhutan, Bangladesh and Myanmar. This paper takes an overview of the carbonatite occurrences in the Indian Subcontinent in the light of recent data. The localities being discussed in detail cover a considerable time range (>2400 Ma to <0.6 Ma) from India (Hogenakal, Newania, Sevathur, Sung Valley, Sarnu-Dandali and Mundwara, and Amba Dongar), Pakistan (Permian Koga and Tertiary Pehsawar Plain Alkaline Complex which includes Loe Shilman, Sillai Patti, Jambil and Jawar), Afghanistan (Khanneshin) and Sri Lanka (Eppawala). This review provide the comprehensive information about geochemical characteristics and evolution of carbonatites in Indian Subcontinent with respect to space and time.

Highlights

  • Carbonatite melts are known to form by very low degrees of partial melting of the carbonated olivine-rich mantle forming interconnected melts at fractions lower than 0.05 wt%

  • In the Indian Subcontinent carbonatites occur in India, Pakistan, Afghanistan and Sri Lanka; but so far not known to occur in Nepal, Bhutan, Bangladesh and Myanmar

  • The localities being discussed in detail cover a considerable time range (>2400 Ma to

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Summary

Introduction

Carbonatite melts are known to form by very low degrees of partial melting of the carbonated olivine-rich (peridotitic) mantle forming interconnected melts at fractions lower than 0.05 wt%. The present paper attempts to review the carbonatite bearing alkaline complexes of the Indian subcontinent; except Bangladesh, Nepal, Bhutan and Myanmar due to absence of carbonatite occurrences (Figure 1). Such occurrences are not considered further in this review. The collision of Indian plate with the Eurasian plate responsible for the Himalayan orogeny, has a profound tectonic influence on the geology of India, Pakistan, Nepal, Bhutan and Afghanistan. Their correlation beyond the geopolitical boundaries is very useful. Notwithstanding above, the present review highlights important and distinguishable characteristics of each of the carbonatite complexes

Carbonatites in space and time
Host rocks and associated silicate rocks
Carbonatite varieties
Fenitization
Mineralogy and Mineral chemistry
10 Whole rock geochemistry
13 Genesis of carbonatites
Findings
14 Economic mineral deposits
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