Slow Si-Al interdiffusion in garnet and stagnation of subducting slabs

Masayuki Nishi, Tomoaki Kubo, Hiroaki Ohfuji, Takumi Kato, Yu Nishihara, Tetsuo Irifune

研究成果: Contribution to journalArticle査読

43 被引用数 (Scopus)

抄録

Si4++M2+↔2Al3+ (M=Mg+Fe+Ca) interdiffusion rates in majoritic garnet have been determined at pressure of 17GPa and temperatures of 1550-1700°C using a Kawai-type high-pressure apparatus. The diffusion profiles were measured across the interface between pyropic garnet and majoritic garnet samples by an analytical transmission electron microscope, and the rate of the Si4++M2+↔2Al3+ interdiffusion was determined to be a DSi-Al (m2s-1)=2×10-10exp [-364 (kJmol-1)/RT]. We found that the diffusion rate is low compared to the Si diffusion rate in other silicate minerals relevant to the deep mantle. Slow kinetics of the pyroxene-garnet transformation due to the low diffusion rate indicates that large low-density metastable regions may exist in the slab, greatly contributing to the slab stagnation around the transition region. Stagnant slabs possibly stay in this region over 108yr because of the sluggish pyroxene-garnet transformation, but may eventually fall into the lower mantle after the completion of the transformation.

本文言語英語
ページ(範囲)44-49
ページ数6
ジャーナルEarth and Planetary Science Letters
361
DOI
出版ステータス出版済み - 1 1 2013

All Science Journal Classification (ASJC) codes

  • 地球物理学
  • 地球化学および岩石学
  • 地球惑星科学(その他)
  • 宇宙惑星科学

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