Define mantle plume and explain its role in plate tectonics.

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Ghissu Editorial · Accepted Answer

A mantle plume is a hot, buoyant column rising from the deep mantle that forms hotspots, records plate motion, splits continents and builds flood basalts. The Reunion plume formed the Deccan Traps about 66 million years ago and is argued to have sped India's northward drift.

**Introduction**

A mantle plume is a column of abnormally hot, buoyant rock rising from deep in the mantle, possibly the core-mantle boundary, with a broad head and narrow tail; at the surface it forms a hotspot. Wilson (1963) and Morgan (1971) built the idea into plate tectonics.

**How a Mantle Plume Works**

FIGURE: geography-p6-3 | Hot Spot and Mantle Plume Formation

1. **Deep source**: Seismic tomography, such as French and Romanowicz's 2015 imaging, shows broad plume conduits rooted near the core-mantle boundary.
2. **Head and tail**: The head melts by decompression under the lithosphere, while the tail feeds a stationary hotspot for millions of years.
3. **Flood basalts**: Plume heads produce large igneous provinces, such as the Deccan Traps from the Reunion plume about 66 million years ago.

**Role of Mantle Plumes in Plate Tectonics**

1. **Recorder of plate motion**: A plate sliding over a fixed plume leaves an age-progressive chain, as in the Hawaiian-Emperor chain, whose bend records a change in Pacific plate motion.
2. **Initiator of rifting**: Plume heads crack continents, as the Afar plume opened the Red Sea, Gulf of Aden and East African Rift.
3. **Driver of plate speed**: Cande and Stegman (2011) argued the Reunion plume pushed India to its fastest northward drift, leaving the Lakshadweep-Chagos ridge as its track.
4. **Explains the exceptions**: Plumes explain volcanism far from boundaries, as at Hawaii and Yellowstone.

**Conclusion**

Mantle plumes add a deep, vertical engine to plate tectonics, though their depth of origin is still debated. For India they explain the Deccan Traps and, arguably, the fast drift that preceded the Himalayan collision.

Define mantle plume and explain its role in plate tectonics.

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