What are mantle plumes and how do they form geological hotspots?

Mantle plumes are proposed upwellings of abnormally hot rock within the Earth's mantle that help explain anomalous volcanism. As a plume head reaches shallow depths and partially melts, it can create volcanic hotspots like Hawaii or Iceland, as well as large igneous provinces. While plume theory suggests these features rise as thermal diapirs from the core-mantle boundary, alternative hypotheses attribute certain hotspots to weak or thin crust that permits passive melting.

What we know

• A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle. [1]
• Mantle plumes are proposed as a convection mechanism to explain volcanic hotspots and large igneous provinces such as the Deccan and Siberian Traps. [2]
• One hypothesis suggests mantle plumes rise as thermal diapirs from the core-mantle boundary. [3]
• The Iceland hotspot contributes to intense volcanic activity and is believed to have a higher temperature and higher concentration of water than the surrounding mantle. [4]

Still open

• While plume theory attributes hotspots to anomalously hot underlying mantle, an alternative plate theory suggests the mantle source is not anomalously hot, and instead a weak or thin crust permits passive melting.
• The exact origins of volcanic activity within tectonic plates remain controversial.

Where to go next

• what followedHow do hotspots create island chains?
• how it workedWhat role does water play in Icelandic volcanism?
• a case in pointWhat are large igneous provinces?
• the bigger pictureHow does plate tectonics explain margin volcanism?
• compared withCould weak crust cause hotspots instead of plumes?
• an unexpected connectionWhy does Iceland have subglacial eruptions?The thermal anomalies of the mantle plume beneath Iceland interact directly with surface ice caps, generating catastrophic glacial bursts alongside basaltic lavas.

Sources

• [1]mantle plume (Wikidata Q878045) · CC0 1.0
• [2]Mantle plume · CC BY-SA 4.0
• [3]Hotspot (geology) · CC BY-SA 4.0
• [4]Iceland hotspot · CC BY-SA 4.0
• [5]Intraplate volcanism · CC BY-SA 4.0