کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5780020 1634698 2017 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Sensitivities of Earth's core and mantle compositions to accretion and differentiation processes
ترجمه فارسی عنوان
حساسیت های هسته و سازهای زمینی زمین به فرآیندهای تکثیر و تمایز
کلمات کلیدی
تشکیل هسته، ترکیب هسته، پارتیشن بندی فلزی سیلیکات، تکامل عناصر سبک، عناصر کمیاب،
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
چکیده انگلیسی


- Combined accretion simulations and partitioning experiments to model core formation.
- Si and O most likely dominate light element budget of Earth's core.
- Earth formed from reduced materials at temperatures near or slightly above liquidus.
- Tradeoff between equilibration depth and amount of metal and silicate equilibrating.
- Core and mantle compositions most sensitive to these factors plus accretion history.

The Earth and other terrestrial planets formed through the accretion of smaller bodies, with their core and mantle compositions primarily set by metal-silicate interactions during accretion. The conditions of these interactions are poorly understood, but could provide insight into the mechanisms of planetary core formation and the composition of Earth's core. Here we present modeling of Earth's core formation, combining results of 100 N-body accretion simulations with high pressure-temperature metal-silicate partitioning experiments. We explored how various aspects of accretion and core formation influence the resulting core and mantle chemistry: depth of equilibration, amounts of metal and silicate that equilibrate, initial distribution of oxidation states in the disk, temperature distribution in the planet, and target:impactor ratio of equilibrating silicate. Virtually all sets of model parameters that are able to reproduce the Earth's mantle composition result in at least several weight percent of both silicon and oxygen in the core, with more silicon than oxygen. This implies that the core's light element budget may be dominated by these elements, and is consistent with ≤1-2 wt% of other light elements. Reproducing geochemical and geophysical constraints requires that Earth formed from reduced materials that equilibrated at temperatures near or slightly above the mantle liquidus during accretion. The results indicate a strong tradeoff between the compositional effects of the depth of equilibration and the amounts of metal and silicate that equilibrate, so these aspects should be targeted in future studies aiming to better understand core formation conditions. Over the range of allowed parameter space, core and mantle compositions are most sensitive to these factors as well as stochastic variations in what the planet accreted as a function of time, so tighter constraints on these parameters will lead to an improved understanding of Earth's core composition.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 458, 15 January 2017, Pages 252-262
نویسندگان
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