Q.Define mantle plume and explain its role in plate tectonics. [150 Words, 10 Marks]
How to approach: Break the explanation into logical causal factors, illustrate with a diagram/flowchart or map where relevant, and link to contemporary relevance.
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- 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.
Question Specifications, Marking Rubric & Syllabus Mapping
| Examination & Year | UPSC Civil Services Mains Examination 2018 (Question 3) |
|---|---|
| Paper & Syllabus Topic | General Studies Paper I — Heritage, History, Society & Geography → Physical, Human & Indian Geography |
| Marks, Word Limit & Ideal Time | 10 Marks • 150 Words • Ideal Writing Time: 7–8 Minutes |
| Directive Word & Core Demand | Explain: Clarify the underlying causes, mechanisms, and significance of the phenomenon in plain, structured terms. |
| Recommended Structure Split | Intro: ~20–25 Words • Body: ~100 Words (3–4 dimensions) • Conclusion: ~20–25 Words |
| AI Practice & Evaluation Tools | Upload Handwritten Answer for 3-Min Vision AI Evaluation | Generate Custom Answer & Mind Map |
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Frequently Asked Questions — UPSC Mains 2018 GS1 (Geography)
How should I structure the answer for this UPSC Mains 2018 GS Paper I question on Geography?
This 2018 GS Paper I question carries 10 marks with a 150-word limit and uses the "Explain" directive. Break the explanation into logical causal factors, illustrate with a diagram/flowchart or map where relevant, and link to contemporary relevance. Follow the ideal word split (Intro: ~20–25 Words • Body: ~100 Words (3–4 dimensions) • Conclusion: ~20–25 Words) and aim to finish within 7–8 Minutes.
Which UPSC Mains syllabus topic does this 2018 question belong to?
This question is part of General Studies Paper I — Heritage, History, Society & Geography under the syllabus module "Physical, Human & Indian Geography". You can explore all repeated questions from Geography in Acme AI's 3D PYQ Realm or filter all Geography PYQs on the Mains PYQ Directory.
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