کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8910407 1637496 2018 33 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Carbonated mantle domains at the base of the Earth's transition zone
ترجمه فارسی عنوان
حوزه های گوشته کربن در پایه منطقه انتقال زمین
کلمات کلیدی
چرخه کربن، غلظت کربن، قابلیت ارتجاعی، محاسبات اولیه اصول، گوشته زمین،
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی
The oxygen fugacity of the upper mantle is 3-4 orders of magnitude higher than that of the lower mantle and this has been attributed to Fe2 + disproportionating into Fe3 + plus Fe0 at pressures > 24 GPa. The upper mantle might therefore have been expected to have evolved to more oxidizing compositions through geological time, but it appears that the oxygen fugacity of the upper mantle has remained constant for the last 3.5 billion years. Thus, it indicates that the mantle has been actively buffered from the accumulation of Fe3 +, and that this is linked to oxidation of diamond to carbonate coupled with reduction of Fe3 + to Fe2 +. When subducted plates penetrate into the lower mantle, compensational upwelling transports bridgmanite into the transition zone, where it breaks down to ringwoodite and majorite, releasing the ferric iron. The system returns to equilibrium through oxidation of diamond. Early in Earth history, diamond may have been enriched at the base of the transition zone in the Magma Ocean, because it is denser than peridotite melts at depths shallower than 660 km, and it is more buoyant below. Ongoing oxidation of diamond forms carbonate, leading to relatively high carbonate concentrations in the source of ocean island basalts.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Geology - Volume 478, 5 February 2018, Pages 69-75
نویسندگان
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