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150 Words10 Marks
Q.Define mantle plume and explain its role in plate tectonics. [150 Words, 10 Marks]
UPSC Mains 2018•Geography
Model Answer
View this Question In PYQ RealmSyllabus Point
- Salient features of World’s Physical Geography.
Approach
- Introduction (30-40 words): Define a mantle plume and its origin.
- Body (170-180 words):
- Explain the role of mantle plumes in plate tectonics (hotspots, rifting, LIPs).
- Provide relevant geological examples.
- Conclusion (30-40 words): Summarize their significance in understanding Earth's dynamic processes.
Introduction
A mantle plume is a localized upwelling of exceptionally hot rock originating from deep within the Earth's mantle, often near the core-mantle boundary. As it rises buoyantly, it melts the lithosphere, generating intense volcanic activity independent of plate boundaries.
Body
Role of Mantle Plumes in Plate Tectonics
- Formation of Hotspots: Plumes create stationary thermal anomalies (hotspots) that cause intraplate volcanism.
- Example: The Hawaiian Island chain was formed as the Pacific Plate moved over a stationary mantle plume.
- Evidence of Plate Motion: The linear progression of volcanic islands or seamounts left by a plume provides direct evidence of tectonic plate speed and direction.
- Example: The Emperor-Hawaiian Seamount Chain tracks the historical movement of the Pacific Plate.
- Continental Rifting and Breakup: Large plumes exert immense thermal and mechanical pressure, fracturing the lithosphere and initiating continental rifting.
- Example: The Deccan Traps in India were created by a mantle plume associated with the breakup of the Gondwana supercontinent.
- Superplume Events: Massive upwellings can alter global mantle convection patterns, influencing overall plate dynamics.
- Example: The African Superplume drives the rifting of the East African Rift System.
- Large Igneous Provinces (LIPs): Plumes trigger massive flood basalt eruptions that shape global geography.
- Example: The Siberian Traps and Columbia River Basalts.
- Oceanic Plateaus: They contribute to the formation of thick oceanic crustal features.
- Example: The Ontong Java Plateau in the Pacific Ocean.
Conclusion
Mantle plumes are vital drivers of Earth's internal heat dissipation, playing a key role in continental breakup, hotspot volcanism, and plate motion tracking, thereby shaping the planet's geological evolution.