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Difficulty: MediumEarth's Interior and Plate Tectonics

A chain of volcanic islands shows a clear age progression where the island at one end has active volcanoes, while the remaining islands become progressively older, extinct, and eroded in one direction. What geological mechanism is responsible for the formation of this island chain?

  1. A
    Subduction of an oceanic plate beneath another oceanic plate at a convergent trench
  2. A tectonic plate moving over a stationary mantle plumeAnswer
  3. C
    Continuous magma upwelling along a divergent mid-ocean ridge
  4. D
    Horizontal shearing and crustal fracturing along a transform fault

Answer

A tectonic plate moving over a stationary mantle plume
A mantle plume (hotspot) remains fixed in a relatively stationary position within the deeper mantle while the overriding tectonic plate moves continuously above it. Magma pierces the crust to form an active volcano; as plate motion carries that volcano away from the plume, the magma supply is cut off, causing the volcano to become extinct and erode while a new volcano forms directly over the hotspot.

Step-by-Step Solution

1
Analyze the spatial and temporal characteristics of the volcanic island chain
The island chain features a single active volcanic center at one end with older, extinct islands aligned in the direction of plate motion.
Differentiating isolated intraplate volcanism from boundary-wide volcanism depends on identifying age progression versus widespread simultaneous activity.
2
Evaluate the geological mechanism capable of producing this pattern
A stationary mantle plume (hotspot) continuously generates magma while the overriding lithospheric plate moves across it, producing an age-progressive track of volcanic islands.
Plate boundary volcanism (convergent arcs and divergent ridges) produces linear zones of simultaneous activity or symmetrical spreading, not a unilateral age progression.

Key Concept

Hotspot volcanism and tectonic plate motion
Estimated Time:1m 0s
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Topics

Earth's Interior and Plate Tectonics

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