کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
11024662 | 1701097 | 2018 | 43 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Rates of dehydration of olivines from San Carlos and Kilauea Iki
ترجمه فارسی عنوان
نرخ های کم آبی بدن از الیوین ها از سان کارلوس و کیلواوا آیکی
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
The results show that the apparent diffusivity of total H+ varies both over time and for olivines with different defect populations, and thus H+ does not diffuse at inherently site-specific rates. These variations are due to rapid reactions that may occur between sites as a function of changing defect concentrations. Our experiments reveal three new phenomena: (1) H+ that is associated with the Ti-clinohumite defect, [Ti-2H], can enter and exit olivine at the fastest rate measured. (2) The rate of H+ loss from specific infrared absorption peaks, and in total, may change with progressive dehydration due to the buildup of Fe3+ and redistribution of defects, particularly the rehydration of [Ti-2H]. (3) The following Arrhenius laws appear to apply to total H+ diffusion out of most natural olivines that have been studied experimentally and naturally during dehydration: Daâ¯=â¯10â5.4exp(â130/RT); Dbâ¯=â¯10â6.9exp(â130/RT); and Dcâ¯=â¯10â6.6exp(â130/RT), where R is the gas constant 8.314â¯J/mol K; T is the temperature, the units of the diffusivities (D) are in m2/s; and the activation energy is 130â¯kJ/mol. This rate is slower than proton-polaron redox rate but faster than proton-metal vacancy diffusion and appears to characterize olivine of Foâ¯â¼90 composition in a wide range of conditions, from self-diffusion, to melt inclusion re-equilibration, to mantle xenolith and volcanic phenocryst zonation during ascent.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 242, 1 December 2018, Pages 165-190
Journal: Geochimica et Cosmochimica Acta - Volume 242, 1 December 2018, Pages 165-190
نویسندگان
Elizabeth Ferriss, Terry Plank, Megan Newcombe, David Walker, Erik Hauri,