کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8906828 | 1634662 | 2018 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Phase stability and thermal equation of state of δ-AlOOH: Implication for water transportation to the Deep Lower Mantle
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
علوم زمین و سیاره ای (عمومی)
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چکیده انگلیسی
In this study, we present new experimental constraints on the phase stability and thermal equation of state of an important hydrous phase, δ-AlOOH, using synchrotron X-ray diffraction up to 142 GPa and 2500 K. Our experimental results have shown that δ-AlOOH remains stable at the whole mantle pressure-temperature conditions above the Dâ³ layer yet will decompose at the core-mantle boundary because of a dramatic increase in temperature from the silicate mantle to the metallic outer core. At the bottom transition zone and top lower mantle, the formation of δ-AlOOH by the decomposition of phase Egg is associated with a â¼2.1-2.5% increase in density (Ï) and a â¼19.7-20.4% increase in bulk sound velocity (VΦ). The increase in Ï across the phase Egg to δ-AlOOH phase transition can facilitate the subduction of δ-AlOOH to the lower mantle. Compared to major lower-mantle phases, δ-AlOOH has the lowest Ï but greatest VΦ, leading to an anomalous low Ï/VΦ ratio which can help to identify the potential presence of δ-AlOOH in the region. More importantly, water released from the breakdown of δ-AlOOH at the core-mantle boundary could lower the solidus of the pyrolitic mantle to cause partial melting and/or react with Fe in the region to form the low-velocity FeO2Hx phase. The presence of partial melting and/or the accumulation of FeO2Hx phase at the CMB could be the cause for the ultra-low velocity zone. δ-AlOOH is thus an important phase to transport water to the lowermost mantle and helps to understand the origin of the ultra-low velocity zone.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 494, 15 July 2018, Pages 92-98
Journal: Earth and Planetary Science Letters - Volume 494, 15 July 2018, Pages 92-98
نویسندگان
Yunfei Duan, Ningyu Sun, Siheng Wang, Xinyang Li, Xuan Guo, Huaiwei Ni, Vitali B. Prakapenka, Zhu Mao,