Along-strike geochemical variations of the Quaternary volcanic rocks in southern Kermadec are classified into two types, “arc-type” (e.g., Rumble V Ridge) and “rift-type” basalts (e.g., Ngatoro Rift), that indicate partial melting and no melting of the subducted sediment, respectively. A recent geochemical study attributed the arc-type basalts to the increased slab surface temperatures resulting from a hot finger-like temperature anomaly in the mantle wedge. To test the existence of the temperature anomaly, we conducted three-dimensional numerical subduction models varying the size of a hot temperature anomaly in the mantle wedge under the Rumble V Ridge. A temperature anomaly with a diameter of 60 km and magnitude of ~ 150 °C increased the slab surface temperature by up to 60 °C and resulted in the localized partial melting of the subducted sediment under the Rumble V Ridge, which is reflected in the arc-type basalts. In addition, the temperature anomaly in the mantle wedge explains the spacing (~ 80 km) between the Rumble V Ridge and Ngatoro Rift. Thus, hot finger-like temperature anomalies in the mantle wedge plausibly explain both the along-strike geochemical variations of the Quaternary volcanic rocks and the spacing between the Rumble V Ridge and Ngatoro Rift in southern Kermadec. High-resolution seismic tomography of the mantle wedge and back-arc mantle could confirm the existence of the temperature anomalies.
Bibliographical noteFunding Information:
Funding information Y.-M. Kim was supported by the Basic Research Project (GP2017-015) of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Science and ICT of Korea. C. Lee was supported by the National Research Foundation of Korea Grant funded by the Ministry of Education, Science and Technology of Korea Government (2016R1D1A1B03930906).
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
All Science Journal Classification (ASJC) codes
- Environmental Science (miscellaneous)
- Geotechnical Engineering and Engineering Geology
- Earth and Planetary Sciences (miscellaneous)