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First Evidence Suggesting Asthenospheric Injectioninto Mantle Wedge of the Izu Arc | |
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2018-02-26 | |
发布年 | 2018 |
语种 | 英语 |
国家 | 日本 |
领域 | 资源环境 |
正文(英文) |
Overview Scientists have identified two types of basalts with different zirconium contents collected from active backarc rift zone of the Izu arc in the northwest Pacific Ocean. Basalts collected at the Sumisu Rift show higher zirconium contents than those from the entire area of the active rift zone. In addition, it has become clear that the distribution of these basalts with higher zirconium contents corresponds with the anomalous zone of low seismic velocity of the underlying mantle wedge. The backarc rifting of the Izu arc began at about 3 million years ago just behind the volcanic front and has made the Aogashima, Myojin and Sumisu Rifts from north to south (Fig. 1). High zirconium contents in basalts from the Sumisu Rift indicate the subducting slab surface beneath the Sumisu Rift is extremely hot because the high zirconium contents result from the melting of zircon of the slab surface. This high temperature and the low seismic velocity of the mantle wedge suggest that hot asthenospheric materials have been injected into the mantle wedge. A typical example of back-arc basins is the Sea of Japan, which spread about 20 million years ago. The underwater “lost continent” of Zealandia in the South Pacific is believed to have separated from Australia due to the formation of backarc basins between the two continents. It has been pointed out that the opening of backarc basin may be related to the injection of deep asthenospheric materials. In this study, scientists have presented the first evidence supporting this hypothesis. Their findings indicate that asthenospheric injection could be a possible driving force of backarc basin opening. This study project was carried out by a research student, Yasuhiro Hirai and Dr. Yoshihiko Tamura from the Japan Agency for Marine Earth Science and Technology (JAMSTEC: President; Asahiko Taira) in collaboration with Profs. Satoshi Okamura from Hokkaido Education University and Ryuichi Shinjo from University of the Ryukyus. This work was supported by JSPS KAKENHI Grant Number JP17H02987.
The above study was published in Geology on February 24, 2018 (JST). Fig. 1. Study area and sampleing points
Fig. 2. A piece of lavas collected from the north of active Smisu Rift.
Fig. 3. Seismic wave (shear wave: S-wave) velocity perturbations beneath the volcanic front of the Izu-Bonin-Mariana arc.
Fig.4. Conceptual diagram of this study Contacts:
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来源平台 | Japan Agency for Marine-Earth Science and Technology |
文献类型 | 新闻 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/104326 |
专题 | 资源环境科学 |
推荐引用方式 GB/T 7714 | admin. First Evidence Suggesting Asthenospheric Injectioninto Mantle Wedge of the Izu Arc. 2018. |
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