Metal–silicate partitioning of tungsten at high pressure and temperature: Implications for equilibrium core formation in Earth

Cottrell, Elizabeth; Walter, Michael J.; Walker, David

doi:10.1016/j.epsl.2009.02.024

Cited by 89 publications

(78 citation statements)

References 54 publications

(102 reference statements)

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“…Metal-silicate reactions between liquid metal and liquid silicates at high P-T have been the subject of a large number of previous studies (e.g., Chabot and Agee, 2003;Chabot et al, 2005;Corgne et al, 2008;Cottrell et al, 2009;Geßmann and Rubie, 1998;Hillgren et al, 1996;Ito et al, 1995;Jana and Walker, 1997;Kegler et al, 2008;Agee, 1996, 2001;Mann et al, 2009;Ohtani et al, 1997;Ricolleau et al, 2011;Righter et al, 1997Righter et al, , 2010Righter et al, , 2011Siebert et al, 2011Siebert et al, , 2012Siebert et al, , 2013Thibault and Walter, 1995;Tsuno et al, 2013;Wade and Wood, 2005;Wood et al, 2009). These studies have produced a wide range of estimates of the effective pressure and temperature of core formation (see Rubie et al (2015b) for a recent review).…”

Section: Introductionmentioning

confidence: 96%

High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O

Fischer

Nakajima

Campbell

et al. 2015

Geochimica et Cosmochimica Acta

207

263

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High pressure metal-silicate partitioning of Ni, Co, V, Cr, Si, and O, Geochimica et Cosmochimica Acta (2015), doi: http://dx.High pressure metal-silicate partitioning of Ni, Co, V, Cr, Si, and O AbstractThe distributions of major and minor elements in Earth's core and mantle were primarily established by high pressure, high temperature metal-silicate partitioning during core segregation. The partitioning behaviors of moderately siderophile elements can be used to constrain the pressure-temperature conditions of core formation and the 2 core's composition. We performed experiments to study the partitioning of Ni, Co, V, Cr, Si, and O between silicate melt and Fe-rich metallic melt in a multianvil press and diamond anvil cell, up to 100 GPa and 5700 K. Combining our new results with data from 18 previous studies, we parameterized the effects of pressure, temperature, and metallic melt composition on partitioning. Ni and Co partitioning are insensitive to composition. At low pressures, these elements become less siderophile with increasing temperature, with this trend reversing above ~45 GPa. V and Cr partitioning are much more sensitive to metallic melt composition and less sensitive to pressure. Partitioning of Si and O are insensitive to pressure, but with strong and moderate temperature dependences, respectively. Our new parameterizations of Ni and Co partitioning suggest that the Earth's distributions of these elements can be matched by single-stage coremantle equilibration at 54 ± 5 GPa and 3300-3400 K. These conditions would result in 8.5 ± 1.4 wt% Si and 1.6 ± 0.3 wt% O in the core, compatible with the core's measured density. However, this single-stage model matches the Earth's V and Cr distributions less well. We also incorporated our parameterizations into models of multi-stage core formation over evolving pressure-temperature-oxygen fugacity conditions, reproducing the Earth's Ni and Co distributions while simultaneously producing a core whose light element composition is consistent with its density.

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Section: Introductionmentioning

confidence: 96%

High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O

Fischer

Nakajima

Campbell

et al. 2015

Geochimica et Cosmochimica Acta

207

263

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“…Based on the FeO content of lunar basalts, the oxygen fugacity of the Moon has been estimated to be approximately one log unit below the iron-wustite buffer (∆IW ≈ −1) or even somewhat higher (Jones and Palme, 2000). D for tungsten at an oxygen fugacity of ∆IW=-1 is ≈ 30 (Cottrell et al, 2009;Walter et al, 2000), and decreases with increasing oxygen fugacity. This value for D W can be compared to that required to generate the high f Hf /W of the lunar mantle by differentiation of a model Moon with a lower bulk f Hf /W .…”

Section: Constraints On Lunar Origin: Evidence For Earth-moon Equilibmentioning

confidence: 99%

“…The tungsten partition coefficient D W is not necessarily constant in either time or space, because the partitioning of W into the core depends on several factors including oxygen fugacity, temperature and pressure (Cottrell et al, 2009). Mars and the Earth exhibit very different Hf/W ratios, suggesting that spatial or temporal variations may be important.…”

Section: Isotopic Calculationsmentioning

confidence: 99%

“…Because significant quantities of water are expected to be found only beyond a certain distance (the snow line) during accretion, the degree of oxidation is expected to increase with distance from the Sun (Pasek et al, 2005;Bond et al, 2009). Because reduced environments result in larger D W values (Cottrell et al, 2009), the Hf/W ratio should decrease with increasing semi-major axis. Variability in oxidation state between different embryos is consistent with the variability of Hf/W ratios seen in parent bodies of differentiated meteorites (Kleine et al, 2004a).…”

Section: Isotopic Calculationsmentioning

confidence: 99%

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Tungsten isotopic evolution during late-stage accretion: Constraints on Earth–Moon equilibration

Nimmo

O’Brien

Kleine

2010

Earth and Planetary Science Letters

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We couple the results of N-body simulations of late-stage accretion (O'Brien et al. 2006) to a hafnium-tungsten (Hf-W) isotopic evolution code to investigate the evolution of planetary bodies in the inner solar system. Simulations can simultaneously produce planets having Earth-and Mars-like masses and Hf-W systematics by assuming that the tungsten partition coefficient decreases with increasing semi-major axis (e.g. due to increasing oxidation). Simulations assuming that Jupiter and Saturn occupy circular orbits are more successful at reproducing the Hf-W systematics than those assuming presentday Jupiter and Saturn orbits. To generate Earth-like tungsten anomalies, 30-80% of each impactor core is required to re-equilibrate with the target mantle. Some model outcomes yield a target and final impactor having similar (Earth-and Moon-like) tungsten anomalies. However, in no case can the inferred lunar Hf/W ratio be simultaneously matched. This result suggests that the Moon isotopically equilibrated with the Earth's mantle in the aftermath of the giant impact (cf. Pahlevan and Stevenson 2007). Alternatively, either the dynamical models which show the Moon being derived primarily from the impactor mantle, or the accretion timescales obtained by the N-body simulations, are incorrect.

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“…We added to this model transport equations describing partitioning (maintaining system mass balance) of the siderophile elements Ni, Co, V, and Nb (in addition to W) between metal and silicate liquids using metal/silicate partition coefficients that are allowed to vary as Earth grows in response to changing pressures and temperatures and redox conditions. To reflect the physical conditions in the mantle up to the values at the core-mantle boundary as Earth grows, we used available thermodynamic fits (to P, T, and f O2 ) of experimentally determined metal-silicate partition coefficients (20,(27)(28)(29)) (see SI Appendix).…”

Section: Modeling Siderophile Element and W Isotopic Evolution Of Thementioning

confidence: 99%

Fast accretion of the Earth with a late Moon-forming giant impact

Jacobsen

2011

Proc. Natl. Acad. Sci. U.S.A.

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Constraints on the formation history of the Earth are critical for understanding of planet formation processes. 182 Hf-182 W chronometry of terrestrial rocks points to accretion of Earth in approximately 30 Myr after the formation of the solar system, immediately followed by the Moon-forming giant impact (MGI). Nevertheless, some N-body simulations and 182 Hf-182 W and 87 Sr chronology of some lunar rocks have been used to argue for a later formation of the Moon at 52 to >100 Myr. This discrepancy is often explained by metal-silicate disequilibrium during giant impacts. Here we describe a model of the 182 W isotopic evolution of the accreting Earth, including constraints from partitioning of refractory siderophile elements (Ni, Co, W, V, and Nb) during core formation, which can explain the discrepancy. Our modeling shows that the concentrations of the siderophile elements of the mantle are consistent with high-pressure metal-silicate equilibration in a terrestrial magma ocean. Our analysis shows that the timing of the MGI is inversely correlated with the time scale of the main accretion stage of the Earth. Specifically, the earliest time the MGI could have taken place right at approximately 30 Myr, corresponds to the end of mainstage accretion at approximately 30 Myr. A late MGI (>52 Myr) requires the main stage of the Earth's accretion to be completed rapidly in <10.7 AE 2.5 Myr. These are the two end member solutions and a continuum of solutions exists in between these extremes.Hf-W chronometry | planet formation C urrent theories and numerical simulations argue that the Earth grew by numerous collisions between small objects to form larger ones and the last collision with a Mars-sized impactor probably gave rise to the Moon (1-3). Because the core formation processes are thought to have been occurring continuously during the accretion, the time scale of core formation in the growing Earth provides a basis for determining the time scale of formation of the Earth-Moon system (4-7). So far, the best constraint on the time scale of formation of the Earth-Moon system is derived from a combination of 182 Hf-182 W chronology and core formation models (cf. 4, 5, 8). A two-stage model with a single core formation event gives the time of Earth's formation of 28-35 Myr after the onset of the solar system (9-11). A model with a continuous accretion and core formation process and an exponentially decreasing accretion rate leads to a mean time of the Earth's formation of 11 AE 1 Myr (9). This is the time needed to accumulate approximately 63% of the present Earth's mass (4). A model with an early continuous accretion and core formation immediately followed by a Moon-forming giant impact (5) yielded a mean time of Earth's formation of approximately 11.5 Myr and a time of the Moon-forming giant impact of approximately 32 Myr (5). Overall, all such models consistently show that the major mass of the Earth has a mean time of formation of approximately 11 Myr with the complete formation time of Earth, including the Moon-formi...

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Metal–silicate partitioning of tungsten at high pressure and temperature: Implications for equilibrium core formation in Earth

Cited by 89 publications

References 54 publications

High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O

High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O

Tungsten isotopic evolution during late-stage accretion: Constraints on Earth–Moon equilibration

Fast accretion of the Earth with a late Moon-forming giant impact

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