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Probing the Lithosphere Under Samoa: A 2500-meter drill core to explore hotspot-trench interactions, continental recycling, the deep biosphere, and geothermal resources

Project Acronym: PLUS | State: Workshop Approved

Volcanic hotspots, like Hawai’i and Samoa, are sourced by mantle plumes that upwell from the deep mantle. Excellent exposure and sampling of Hawaiian volcanoes provide data for what has been considered the prototypical model for ocean island evolution worldwide. Available data, however, suggest that Samoan volcanoes grow in a manner very different from Hawai’i. To better understand how a Samoan volcano grows and evolves, this proposal seeks funding for a workshop to discuss drilling a 2500 m borehole on the Samoan island of Savai’i. In addition to providing a critical counterpoint to the “Hawaiian model,” the drill core will help address long-standing problems associated with the evolution of a Samoan volcano, including: 1) evaluating the poorly-understood genesis of Samoan lavas with extreme continental signatures recovered by dredging the deep submarine flanks of Savai’i; 2) investigating the near-absence of tholeiites in the Samoan shield stage in light of their ubiquity at Hawaii; 3) testing a possible plate flexure origin for the unusual volumes of rejuvenated lava on Savai’i that takes into account Savai’i’s juxtaposition with the nearby Tonga trench. This will shed light into the globally relevant problems of how different tectonic mechanisms interact with mantle plumes to modulate hotspot volcanism.

Keywords: Oceania, Samoa, Volcanic Hotspot, Mantle Plume, Plate Flexure, Hydrothermal, Deep Biosphere

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Workshop Proposal Approved