کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4678398 1634845 2010 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
High-temperature compression of ferropericlase and the effect of temperature on iron spin transition
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
High-temperature compression of ferropericlase and the effect of temperature on iron spin transition
چکیده انگلیسی
High-temperature compression experiments with in situ X-ray diffraction of ferropericlase (Fp) with a composition of (Mg0.81Fe0.19)O were made in a laser-heated diamond anvil cell to pressures (P) of 116 GPa at a constant temperature (T) of 1600-1900 K. Room-temperature experiments with a laser annealing technique were also carried out on the same material. Anomalous unit-cell volume reductions that can be explained by the spin transition of ferrous iron were observed at P = 63-96 GPa and 45-63 GPa at T = 1600-1900 K and 300 K, respectively, indicating that the spin transition pressure interval expands with increasing temperature. The observed density changes across this spin transition at T = 1600-1900 K and 300 K are about 1.6% and 1.0%, respectively, indicating that the spin transition pressure interval expands with increasing temperature. The thermal expansivity of Fp is large in the mid-lower mantle due to the effect of the spin transition. In a peridotitic composition, the spin transition in Fp increases the rock density by 0.35% at the lowermost mantle conditions. Calculated densities show that both perovskitic and peridotitic mantle models may explain the PREM lower mantle density. However, the peridotitic lower mantle model requires less assumption to satisfy the PREM density and is more self-consistent.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 297, Issues 3–4, 1 September 2010, Pages 691-699
نویسندگان
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