Distinct ages and mantle sources for Southern Ocean oceanic plateaus

The Agulhas Plateau, Maud Rise, and Northeast Georgia Rise are large oceanic plateaus previously interpreted as fragments of a single large igneous province formed at the Bouvet triple junction, and subsequently separated by rifting. However, limited age and geochemical constraints for these plateaus in the Southern Ocean have hindered a robust evaluation of this model. Here we present new 40 Ar/ 39 Ar ages from igneous rocks cored during IODP Expedition 392 on the Agulhas Plateau, together with new and compiled Sr-Nd-Pb-Hf isotope geochemistry from Agulhas Plateau, Maud Rise, Northeast Georgia Rise and the Mozambique Ridge to investigate possible cogenetic origins. Our ages indicate that the youngest magmatism on the Agulhas Plateau took place between 87 and 80 Ma. Radiogenic isotope compositions show that Agulhas lavas form a distinct compositional field characterized by relatively depleted Sr, Nd, and Hf isotopic signatures, and Pb isotope ratios that plot near the Northern Hemisphere Reference Line. In contrast, Maud Rise lavas display more enriched and DUPAL-like isotopic signatures that closely resemble those of the Mozambique Ridge, while Northeast Georgia Rise lavas have intermediate isotopic compositions. Integration of geochronological, geochemical, and seafloor magnetic constraints suggests that the Agulhas Plateau and Northeast Georgia Rise likely formed together around 90 Ma from a ridge-centered Bouvet hotspot, whereas Maud Rise more likely formed earlier together with the Mozambique Ridge. These results demonstrate that Southern Ocean oceanic plateaus formed during at least two episodes of plume-influenced magmatism associated with evolving plate boundary geometries.

Authors

Institutions

Publication Details

Journal
Earth and Planetary Science Letters
Published
2026-08-03
DOI
https://doi.org/10.1016/j.epsl.2026.120219
Primary Topic
Geological and Geochemical Analysis
Type
article
Field-Weighted Citation Impact
0.00

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Distinct ages and mantle sources for Southern Ocean oceanic plateaus

Edoardo Dallanave, Shannon J. Haynes, Allyson C. Tessin, Juan Li et al.
Earth and Planetary Science Letters
Geological and Geochemical Analysis
article

Distinct ages and mantle sources for Southern Ocean oceanic plateaus

Edoardo Dallanave, Shannon J. Haynes, Allyson C. Tessin, Juan Li, Daniel E. Heaton, Folkmar Hauff, Steve Bohaty, Anthony Koppers, Pratyusha Chanda, Kelsey E. Doiron, Thomas Westerhold, Derya Gürer, Chie Kato, Odysseas A. Archontikis, Jörg Geldmacher, Sietske J. Batenburg, Debadrita Jana, Matthew M. Jones, Thomas Wagner, Alexander Minakov, Courtney Sprain, Peter Bijl, Denise Kulhanek, Kaj Hoernle, Peter C. Davidson, Donald E. Penman, Jia Liu, Laurel Childress, Brian Huber, Gabriele Uenzelmann-Neben, Daniel A. Frick, Yuji Ichiyama
article en

Abstract

The Agulhas Plateau, Maud Rise, and Northeast Georgia Rise are large oceanic plateaus previously interpreted as fragments of a single large igneous province formed at the Bouvet triple junction, and subsequently separated by rifting. However, limited age and geochemical constraints for these plateaus in the Southern Ocean have hindered a robust evaluation of this model. Here we present new 40 Ar/ 39 Ar ages from igneous rocks cored during IODP Expedition 392 on the Agulhas Plateau, together with new and compiled Sr-Nd-Pb-Hf isotope geochemistry from Agulhas Plateau, Maud Rise, Northeast Georgia Rise and the Mozambique Ridge to investigate possible cogenetic origins. Our ages indicate that the youngest magmatism on the Agulhas Plateau took place between 87 and 80 Ma. Radiogenic isotope compositions show that Agulhas lavas form a distinct compositional field characterized by relatively depleted Sr, Nd, and Hf isotopic signatures, and Pb isotope ratios that plot near the Northern Hemisphere Reference Line. In contrast, Maud Rise lavas display more enriched and DUPAL-like isotopic signatures that closely resemble those of the Mozambique Ridge, while Northeast Georgia Rise lavas have intermediate isotopic compositions. Integration of geochronological, geochemical, and seafloor magnetic constraints suggests that the Agulhas Plateau and Northeast Georgia Rise likely formed together around 90 Ma from a ridge-centered Bouvet hotspot, whereas Maud Rise more likely formed earlier together with the Mozambique Ridge. These results demonstrate that Southern Ocean oceanic plateaus formed during at least two episodes of plume-influenced magmatism associated with evolving plate boundary geometries.

Earth and Planetary Science LettersVol. 692
Smithsonian Institution (US), Utah State University (US), Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (DE), Planetary Science Institute (US), Oregon State University (US), National Museum of Natural History (US), Kyushu University (JP), Harvard University (US), Kent State University (US), Chiba University (JP), University of Bremen (DE), University of Oslo (NO), University of Milan (IT), Utrecht University (NL), National Oceanography Centre (GB), Princeton University (US), Heidelberg University (DE), Christian-Albrechts-Universität zu Kiel (DE), Heriot-Watt University (GB), University of Florida (US), GEOMAR Helmholtz Centre for Ocean Research Kiel (DE), University of Oxford (GB), University of Southampton (GB), Zhejiang University (CN), Nanjing University (CN), Texas A&M University (US)
United States Science Support Program, Deutsche Forschungsgemeinschaft
Life below water
Openalex Percentile: Top 11%
Geological and Geochemical Analysis
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.