Tracking missing mantle plume in ancient Samoa: researchers shed light on 30 million year gap

Bathymetric map of the Pacific region focusing on the trajectory of Samoa’s Hotspot 100 Mil, from Samoa’s hotspot active volcanoes (Vailuluu Seamount) to the Dutton Ridge (near the Mariana Trench). Credit: AGU Advances (2024). DOI: 10.1029/2023AV001079
As magma plumes rise through the Earth’s lithosphere, volcanoes, islands, seamounts, and other features form on the Earth’s surface. As tectonic plates move over these plumes, they form distinct hotspot trails that mark the plume’s position and the movement of the crust above it over time.
The most famous of these routes in the Pacific include the Hawaiian Islands. Another trajectory includes the Samoan Islands, but the trajectory is interrupted by a strange gap that represents roughly 30 million years of Earth’s history.
MG Jackson and colleagues have discovered an explanation for the missing part of the Samoan hotspot track, determining that its older section, which extends into the Mariana Trench, dates back 100 million years. The research will be published in the journal AGU Advances.
The authors suggest that about 60 million years ago, the movement of the Pacific plate carried the Ontong Java Plateau, a large volcanic region with a very thick lithosphere, onto the Samoan plume. This plateau effectively covered the plume for 30 million years, suppressing mantle melting and preventing the formation of new volcanic structures, resulting in a 30 million year gap in the Samoan archipelago.
By combining isotopic and geochronological data from lava samples with plate motion models, the researchers were able to link older and younger parts of the hotspot trail. Key to their research was new evidence discovered on Malaita Island, part of the Solomon Islands, about 3,000 kilometers east of Samoa.
There, researchers discovered 44-million-year-old volcanic rock on the edge of the Ontong Java Plateau with a geochemical fingerprint consistent with lava from the Samoan hotspot. This discovery suggested that the eruptions that produced the rocks originated from the same hotspot, providing a missing link between the sections.
The authors outline a scenario in which the Ontong Java Plateau suppressed or diverted magma from the Samoan plume, and argue that mantle melting was probably largely suppressed, with the possible exception of the Malaita lava. They say this new study identifies a previously unknown geological process called the “plume plateau” interaction, and fleshes out previous theories about the hotspot’s history.
The authors found evidence of this process elsewhere, suggesting that the Ontong Java Plateau also moved and suppressed the Rarotonga hotspot, and that the Manihiki Plateau similarly suppressed the Pitcairn Island and Society hotspots. did. All three hot spots are associated with the formation of the eponymous island.
As a side note, Shichun Huang said that the plateau may not necessarily be thick enough to completely prevent plume melting, so that concentrated material that melts at lower temperatures may preferentially melt. It suggests that there is. Such preferential melting could mean that hotspot lava does not necessarily represent the plume from which it came.
In addition, Huang said, the occurrence of plume-plateau interactions could limit the global flow of material from mantle plumes, as some plumes can become temporarily capped and become unproductive. It points out that it may mean that it is undervalued.
Further information: MG Jackson et al, “When the plateau suppresses the plume: Disappearance of the Samoan plume beneath the Ontong Java Plateau,” AGU Advances (2024). DOI: 10.1029/2023AV001079
Shichun Huang, Plume-Plateau Interaction, AGU Advance (2024). DOI: 10.1029/2024AV001464
This article is republished courtesy of Eos, sponsored by the American Geophysical Union. Read the original story here.
Citation: Tracking missing mantle plume in ancient Samoa: Researchers shed light on 30 million-year gap (October 28, 2024) https://phys.org/news/2024-10-tracking-mantle Retrieved October 28, 2024 from-Plume-Ancient Samoa.html
This document is subject to copyright. No part may be reproduced without written permission, except in fair dealing for personal study or research purposes. Content is provided for informational purposes only.