Earth's chondritic Th/U: Negligible fractionation during accretion, core formation, and crust-mantle differentiation

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F18%3A10384816" target="_blank" >RIV/00216208:11320/18:10384816 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1016/j.epsl.2018.06.029" target="_blank" >https://doi.org/10.1016/j.epsl.2018.06.029</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.epsl.2018.06.029" target="_blank" >10.1016/j.epsl.2018.06.029</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Earth's chondritic Th/U: Negligible fractionation during accretion, core formation, and crust-mantle differentiation

Popis výsledku v původním jazyce

Radioactive decay of potassium (K), thorium (Th), and uranium (U) power the Earth&apos;s engine, with variations in Th-232/U-238 recording planetary differentiation, atmospheric oxidation, and biologically mediated processes. We report several thousand Th-232/U-238 (kappa) and time-integrated Pb isotopic (kappa(Pb)) values and assess their ratios for the Earth, core, and silicate Earth. Complementary bulk silicate Earth domains (i.e., continental crust kappa(CC)(Pb) = 3.95(-0.13)(+0.19) and modern mantle kappa(MM)(Pb) = 3.87(-0.07)(+0.15)) tightly bracket the solar system initial kappa(SS)(Pb) = 3.890 +/- 0.015. These findings reveal the bulk silicate Earth&apos;s kappa(BSE)(Pp) is 3.90(-0.08)(+0.13) (or Th/U = 3.77 for the mass ratio), which resolves a long-standing debate regarding the Earth&apos;s Th/U value. We performed a Monte Carlo simulation to calculate the kappa(Pb) of the BSE and bulk Earth for a range of U concentrations in the core (from 0 to 10 ng/g). Comparison of our results with kappa(SS)(Pb) constrains the available U and Th budget in the core. Negligible Th/U fractionation accompanied accretion, core formation, and crust-mantle differentiation, and trivial amounts of these elements (&lt;0.2 ng/g U) were added to the core and do not significantly power (similar to 0.03 TW) the geodynamo. (C) 2018 Elsevier B.V. All rights reserved.

Název v anglickém jazyce

Earth's chondritic Th/U: Negligible fractionation during accretion, core formation, and crust-mantle differentiation

Popis výsledku anglicky

Radioactive decay of potassium (K), thorium (Th), and uranium (U) power the Earth&apos;s engine, with variations in Th-232/U-238 recording planetary differentiation, atmospheric oxidation, and biologically mediated processes. We report several thousand Th-232/U-238 (kappa) and time-integrated Pb isotopic (kappa(Pb)) values and assess their ratios for the Earth, core, and silicate Earth. Complementary bulk silicate Earth domains (i.e., continental crust kappa(CC)(Pb) = 3.95(-0.13)(+0.19) and modern mantle kappa(MM)(Pb) = 3.87(-0.07)(+0.15)) tightly bracket the solar system initial kappa(SS)(Pb) = 3.890 +/- 0.015. These findings reveal the bulk silicate Earth&apos;s kappa(BSE)(Pp) is 3.90(-0.08)(+0.13) (or Th/U = 3.77 for the mass ratio), which resolves a long-standing debate regarding the Earth&apos;s Th/U value. We performed a Monte Carlo simulation to calculate the kappa(Pb) of the BSE and bulk Earth for a range of U concentrations in the core (from 0 to 10 ng/g). Comparison of our results with kappa(SS)(Pb) constrains the available U and Th budget in the core. Negligible Th/U fractionation accompanied accretion, core formation, and crust-mantle differentiation, and trivial amounts of these elements (&lt;0.2 ng/g U) were added to the core and do not significantly power (similar to 0.03 TW) the geodynamo. (C) 2018 Elsevier B.V. All rights reserved.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10500 - Earth and related environmental sciences

Projekt

<a href="/cs/project/GA17-01464S" target="_blank" >GA17-01464S: Studium radiogenního zahřívání Země metodami částicové geofyziky: geoneutrina a vzácné plyny</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Earth and Planetary Science Letters

ISSN

0012-821X

e-ISSN

—

Svazek periodika

498

Číslo periodika v rámci svazku

September

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

7

Strana od-do

196-202

Kód UT WoS článku

000442060600017

EID výsledku v databázi Scopus

2-s2.0-85049555784