Question

Which of the following statements is NOT true about mantle plumes?

A. They may occur far from plate boundaries.
B. They appear to be rooted deep in the mantle.
C. The basalt that erupts from mantle plume volcanoes is geochemically different from other volcanoes
D. They never appear below the oceanic crust.

Answer 1

The statement that is NOT true about mantle plumes is option D. They never appear below the oceanic crust they can in fact produce volcanoes such as those in the Hawaiian Islands.

Step-by-step explanation:

Mantle plumes can indeed appear below the oceanic crust and result in the formation of volcanic islands such as the Hawaiian Islands, which are formed over the Hawaii hotspot. Mantle plumes are upwellings of abnormally hot rock within the Earth's mantle and can occur far from plate boundaries (A), are rooted deep in the mantle (B), and the basalt that erupts from mantle plume volcanoes has unique geochemical signatures (C).

When tectonic plates move over a stationary hotspot, a chain of volcanoes can form. If a hotspot is located under oceanic crust, it produces basalts, which are characteristic of ocean island basalt (OIB) chemistry. This demonstrates the fact that mantle plumes can, and do, exist beneath both continental and oceanic crust.