@article{ef1b8bea08ff4c18a9642cda672a92e8,
title = "Sharp 660-km discontinuity controlled by extremely narrow binary post-spinel transition",
abstract = "The Earth{\textquoteright}s mantle is characterized by a sharp seismic discontinuity at a depth of 660 km that can provide insights into deep mantle processes. The discontinuity occurs over only 2 km—or a pressure difference of 0.1 GPa—and is thought to result from the post-spinel transition, that is, the decomposition of the mineral ringwoodite to bridgmanite plus ferropericlase. Existing high-pressure, high-temperature experiments have lacked the pressure control required to test whether such sharpness is the result of isochemical phase relations or chemically distinct upper and lower mantle domains. Here, we obtain the isothermal pressure interval of the Mg–Fe binary post-spinel transition by applying advanced multi-anvil techniques with in situ X-ray diffraction with the help of Mg–Fe partition experiments. It is demonstrated that the interval at mantle compositions and temperatures is only 0.01 GPa, corresponding to 250 m. This interval is indistinguishable from zero at seismic frequencies. These results can explain the discontinuity sharpness and provide new support for whole-mantle convection in a chemically homogeneous mantle. The present work suggests that distribution of adiabatic vertical flows between the upper and lower mantles can be mapped on the basis of discontinuity sharpness.",
author = "Takayuki Ishii and Rong Huang and Robert Myhill and Hongzhan Fei and Iuliia Koemets and Zhaodong Liu and Fumiya Maeda and Liang Yuan and Lin Wang and Dmitry Druzhbin and Takafumi Yamamoto and Shrikant Bhat and Robert Farla and Takaaki Kawazoe and Noriyoshi Tsujino and Eleonora Kulik and Yuji Higo and Yoshinori Tange and Tomoo Katsura",
note = "Funding Information: We appreciate H. Fischer, S. {\"U}belhack, R. Njul, H. Schulze, U. Trenz and S. Linhardt at Bayerisches Geoinstitut for their technical assistance. We acknowledge N. Tomioka, A. Shatskiy, G. Manthilake, S.-M. Zhai, K. Saito, K. Kawabe, E. Ito, A. Kubo, S. Okita, T. Okishio, M. Sugita, M. Matsui, A. Kuwata, M.-S. Song and S. Yokoshi for their participation in the early stage of this study (2003–2004). This work was supported by the research project approved by DFG (KA 3434/7-1, KA3434/8-1, KA3434/9-1) and BMBF (05K16WC2) to T. Katsura and DFG (IS 350/1-1) to T.I. This project has been also supported by the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (proposal no. 787 527). T.I. has been supported by a research fellowship for scientific research from the Japan Society for the Promotion of Science (JSPS) for Young Scientists, an overseas research fellowship from the Scientific Research of the JSPS for Young Scientists and an Alexander von Humboldt Postdoctoral Fellowship. The synchrotron X-ray diffraction experiments were performed in the beamline BL04B1 at SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (proposal no. 2003A0087, 2003B0638, 2004A0368, 2004B0497, 2015A1359, 2015B1196, 2016A1172, 2016A1274, 2016A1434, 2016B1094, 2017A1150, 2018A1071, 2018B1218). Publisher Copyright: {\textcopyright} 2019, The Author(s), under exclusive licence to Springer Nature Limited.",
year = "2019",
month = oct,
day = "1",
doi = "10.1038/s41561-019-0452-1",
language = "English",
volume = "12",
pages = "869--872",
journal = "Nature Geoscience",
issn = "1752-0894",
publisher = "Nature Publishing Group",
number = "10",
}