کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4677830 1634821 2011 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Iron-rich perovskite in the Earth's lower mantle
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Iron-rich perovskite in the Earth's lower mantle
چکیده انگلیسی

The equations of state of perovskite with (Mg0.75,Fe0.25)SiO3 and MgSiO3 compositions have been investigated by synchrotron X-ray diffraction up to 130 GPa at 300 K in diamond anvil cells. Here we show that the addition of 25% Fe in MgSiO3 perovskite increases its density and bulk sound velocity (VФ) by 4–6% and 6–7%, respectively, at lower-mantle pressures. Based on concurrent synchrotron X-ray emission and Mössbauer spectroscopic studies of the samples, the increase in VФ and density can be explained by the occurrence of the low-spin Fe3+ and the extremely high-quadrupole component of Fe2+. Combining these experimental results with thermodynamic modeling, our results indicate that iron-rich perovskite can produce an increase in density and a value of VФ that is compatible with seismic observations of reduced shear-wave velocity in regions interpreted as dense, stiff piles in the lower mantle. Therefore, the existence of the Fe-rich perovskite in the lower mantle may help elucidate the cause of the lower-mantle large low-shear-velocity provinces (LLSVPs) where enhanced density and VФ are seismically observed to anti-correlate with the reduced shear wave velocity.


► We have studied the equation of states of perovskite with 25% Fe and without Fe.
► A 4-7% increase in the density and VΦ at lower-mantle pressures was observed.
► The increase is explained as a result of the low-spin Fe3+ and high QS Fe2+.
► 4.An excess of 15% iron in perovskite may explain large-low-shear velocity provinces.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 309, Issues 3–4, 15 September 2011, Pages 179–184
نویسندگان
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