Subduction of the oceanic Hikurangi Plateau and its impact on the Kermadec arc
2014
Large igneous province subduction is a rare process on Earth. A modern example is the
subduction of the oceanic Hikurangi Plateau beneath the southern Kermadec arc, offshore
New Zealand. This segment of the arc has the largest total lava volume erupted and the
highest volcano density of the entire Kermadec arc. Here we show that Kermadec arc lavas
south of B32°S have elevated Pb and Sr and low Nd isotope ratios, which argues, together
with increasing seafloor depth, forearc retreat and crustal thinning, for initial Hikurangi
Plateau—Kermadec arc collision B250 km north of its present position. The combined data
set indicates that a much larger portion of the Hikurangi Plateau (the missing Ontong Java
Nui piece) than previously believed has already been subducted. Oblique plate convergence
caused southward migration of the thickened and buoyant oceanic plateau crust, creating a
buoyant ‘Hikurangi’ me´lange beneath the Moho that interacts with ascending arc melts.
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