Anomalous uplift and subsidence of the Ontong Java Plateau inferred from CO<inf>2</inf> contents of submarine basaltic glasses

Julie Roberge, Paul J. Wallace, Rosalind V. White, Millard F. Coffin

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Abstract

The Ontong Java Plateau in the western Pacific is anomalous compared to other oceanic large igneous provinces in that it appears to have never formed a large subaerial plateau. Paleoeruption depths (at 122 Ma) estimated from dissolved H2O and CO2 in submarine basaltic glass pillow rims vary from ∼1100 m below sea level (mbsl) on the central part of the plateau to 2200-3000 mbsl on the northeastern edge. Our results suggest maximum initial uplift for the plateau of 2500-3600 m above the surrounding seafloor and 1500 ± 400 m of postemplacement subsidence since 122 Ma. Our estimates of uplift and subsidence for the plateau are significantly less than predictions from thermal models of oceanic lithosphere, and thus our results are inconsistent with formation of the plateau by a high-temperature mantle plume. Two controversial possibilities to explain the anomalous uplift and subsidence are that the plateau (1) formed as a result of a giant bolide impact, or (2) formed from a mantle plume but has a lower crust of dense garnet granulite and/or eclogite; neither of these possibilities is fully consistent with all available geological, geophysical, and geochemical data. The origin of the largest magmatic event on in Earth in the past 200 m.y. thus remains an enigma. © 2005 Geological Society of America.
Original languageAmerican English
Pages (from-to)501-504
Number of pages450
JournalGeology
DOIs
StatePublished - 1 Jun 2005
Externally publishedYes

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