Collision-induced post-plateau volcanism: Evidence from a seamount on Ontong Java Plateau

Takeshi Hanyu, Maria Luisa G. Tejada, Kenji Shimizu, Osamu Ishizuka, Toshiyuki Fujii, Jun Ichi Kimura, Qing Chang, Ryoko Senda, Takashi Miyazaki, Yuka Hirahara, Bogdan S. Vaglarov, Kosuke T. Goto, Akira Ishikawa

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Abstract

Many seamounts on the Ontong Java Plateau (OJP) occur near the Stewart Arch, a topographic high that extends parallel to the North Solomon Trench along the southern margins of the plateau. Despite the thick sediment cover, several volcanic cones with strong acoustic reflection were discovered on the submarine flank of the Nuugurigia Seamount. From such volcanic cones, basalts were successfully sampled by dredging. Radiometric dating of basalts and ferromanganese encrustation indicate eruption age of 20–25 Ma, significantly younger than the ~ 122 Ma main OJP plateau and post-plateau basalts. The age range coincides with the collision of the OJP with the Solomon Arc. The Nuugurigia basalts geochemically differ from any other rocks sampled on the OJP so far. They are alkali basalts with elevated Sr, low Zr and Hf, and Enriched Mantle-I (EMI)-like isotopic composition. Parental magmas of these alkali basalts may have formed by small-degree melting of peridotitic mantle impregnated with recycled pyroxenite material having enriched geochemical composition in the OJP's mantle root. We conclude that small-volume alkali basalts from the enriched mantle root migrated through faults or fractures caused by the collision along the Stewart Arch to form the seamount. Our results suggest that the collision of the OJP with the Solomon arc played an important role in the origin of similar post-plateau seamounts along the Stewart Arch.

Original languageEnglish
Pages (from-to)87-96
Number of pages10
JournalLITHOS
Volume294-295
DOIs
Publication statusPublished - Dec 1 2017

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All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Cite this

Hanyu, T., Tejada, M. L. G., Shimizu, K., Ishizuka, O., Fujii, T., Kimura, J. I., ... Ishikawa, A. (2017). Collision-induced post-plateau volcanism: Evidence from a seamount on Ontong Java Plateau. LITHOS, 294-295, 87-96. https://doi.org/10.1016/j.lithos.2017.09.029