Recycling of depleted continental mantle by subduction and plumes at the Hikurangi Plateau large igneous province, southwestern Pacific Ocean | Zendy

Kimihiro Mochizuki | Zendy; R. Sutherland | Zendy; Stuart Henrys | Zendy; Dan Bassett | Zendy; Harm J. A. Van Avendonk | Zendy; Ryuta Arai | Zendy; Shuichi Kodaira | Zendy; Gou Fujie | Zendy; Yojiro Yamamoto | Zendy; Nathan L. Bangs | Zendy; D. H. N. Barker | Zendy

Open Access

Recycling of depleted continental mantle by subduction and plumes at the Hikurangi Plateau large igneous province, southwestern Pacific Ocean

Author(s) -

Kimihiro Mochizuki,

R. Sutherland,

Stuart Henrys,

Dan Bassett,

Harm J. A. Van Avendonk,

Ryuta Arai,

Shuichi Kodaira,

Gou Fujie,

Yojiro Yamamoto,

Nathan L. Bangs,

D. H. N. Barker

Publication year - 2019

Publication title -

geology

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 2.609

H-Index - 215

eISSN - 1943-2682

pISSN - 0091-7613

DOI - 10.1130/g46250.1

Subject(s) - geology , mantle (geology) , subduction , mantle plume , craton , lithosphere , hotspot (geology) , crust , mantle wedge , transition zone , crustal recycling , mantle convection , geochemistry , continental crust , geophysics , seismology , tectonics

Seismic reflection and refraction data from Hikurangi Plateau (southwestern Pacific Ocean) require a crustal thickness of 10 ± 1 km, seismic velocity of 7.25 ± 0.35 km/s at the base of the crust, and mantle velocity of 8.30 ± 0.25 km/s just beneath the Moho. Published models of gravity data that assume normal crust and mantle density predict 5–10-km-thicker crust than we observe, suggesting that the mantle beneath Hikurangi Plateau has anomalously low density, which is inconsistent with previous suggestions of eclogite to explain observations of high seismic velocity. The combination of high seismic velocity and low density requires the mantle to be highly depleted and not serpentinized. We propose that Hikurangi Plateau formed by decompression melting of buoyant mantle that was removed from a craton root by subduction, held beneath 660 km by viscous coupling to slabs, and then rose as a plume from the lower mantle. Ancient Re-Os ages from mantle xenoliths in nearby South Island, New Zealand, support this hypothesis. Erosion of buoyant depleted mantle from craton roots by subduction and then recycling in plumes to make new lithosphere may be an important global geochemical process.

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