241-5 Rocky Planets, Fiery Hearts: A Plume Story

Session: Petrology, Volcanology, and Mantle Plumes across the Solar System, Part I

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Planets form hot and fast, then slowly cool through time. The processes associated with cooling give rise to the volcanic, tectonic, and seismic features we study. The transfer of heat from a planet’s deep interior, assumed to originate at the core-mantle boundary, to the surface (more correctly the base of the lithosphere) takes the form of a plume. The link between plumes within the Earth and surface observations is enigmatic, so the sparse observations available on other terrestrial planets ensure that identifying plumes within these bodies would be even more cryptic than on Earth. Starting with Venus, Earth’s hotter twin, the strong correlation between gravity and topography is likely a signature of mantle plumes at some plateaus. Coronae, enigmatic circular tectono-volcanic features unique to Venus, are thought to be formed by diapirs interacting with the lithosphere. We can ask whether there is a link between these coronae-forming diapirs and mantle plumes and if so, how we can reconcile these with the plateaus also thought to be supported by mantle plumes. Moving to Mars, the buildup of the Tharsis plateau, a continent-sized volcanic plateau centered near the equator in the western hemisphere, draws the immediate attention of the pondering scientist and they might ask if Mars is a one plume planet. Yet while Elysium Mons is dwarfed by Tharis, it is still larger in volume than the Ontong Java Plateau, the largest of the large igneous provinces on Earth. Even Mercury with its notably thin silicate shell of just 400 km has an extensive area of volcanically emplaced plains. Is this also the result of a plume or is did it form by some other process?  The expression of volcanic activity on each planet is unique yet, fluid dynamics shows that hot upwellings take the form of instabilities, generally called plumes, from the bottom of a spherical shell (often the core-mantle boundary). How does plate tectonics interact with upwelling plumes? Is upwelling dynamics on stagnant lid planets easier to understand or do we just have fewer, sometimes seemingly contradictory, observations? The end of the plume story has not yet been written.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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