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Breaking up is hard to do: Magmatism during oceanic arc breakup, subduction reversal, and cessation

January 16, 2023

The formerly continuous Vitiaz Arc broke into its Vanuatu and Fijian portions during a reversal of subduction polarity in the Miocene. Basaltic volcanism in Fiji that accompanied the breakup ranged from shoshonitic to low-K and boninitic with increasing distance from the broken edge of the arc that, presumably, marks the broken edge of the slab. The Sr-Pb-Nd isotope ratios of the slab-derived component in the breakup basalts most closely match those of the isotopically most depleted part of the Samoan seamount chain on the Pacific Plate that was adjacent to the site of breakup at 4-8 Ma, and differ from those of subsequent basalts in spreading segments of the surrounding backarc North Fiji and Lau Basins. Subduction of the Samoan Chain along the Vitiaz Trench Lineament may have controlled the limit of polarity reversal and, hence, where the double saloon doors (Martin, 2013) opened. Prior to breakup, Fijian volcanics were more similar isotopically to the Louisville Seamount Chain.

Citation Information

Publication Year 2022
Title Breaking up is hard to do: Magmatism during oceanic arc breakup, subduction reversal, and cessation
DOI 10.1029/2022GC010663
Authors James F. Gill, Erin Todd, Kaj Hoernle, Folkmar Hauff, Alison Ann Price, Matthew G. Jackson
Publication Type Article
Publication Subtype Journal Article
Series Title Geochemistry, Geophysics, Geosystems
Index ID 70239730
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center

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