scholarly journals Diamond Anvil Cell Partitioning Experiments for Accretion and Core Formation: Testing the Limitations of Electron Microprobe Analysis

2019 ◽  
Vol 25 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Eleanor S. Jennings ◽  
Jon Wade ◽  
Vera Laurenz ◽  
Sylvain Petitgirard
Keyword(s):  
Microprobe Analysis ◽  
Element Distribution ◽  
Planetary Scale ◽  
Element Partitioning ◽  
Metal Silicate ◽  
Diamond Anvil ◽  
Cell Partitioning ◽  
Two Phases ◽  
Laser Heated ◽  
Tem Grid

AbstractMetal–silicate partitioning studies performed in high-pressure, laser-heated diamond anvil cells (DAC) are commonly used to explore element distribution during planetary-scale core–mantle differentiation. The small run-products contain suitable areas for analysis commonly less than tens of microns in diameter and a few microns thick. Because high spatial resolution is required, quantitative chemical analyses of the quenched phases is usually performed by electron probe microanalysis (EPMA). Here, EPMA is being used at its spatial limits, and sample thickness and secondary fluorescence effects must be accounted for. By using simulations and synthetic samples, we assess the validity of these measurements, and find that in most studies DAC sample wafers are sufficiently thick to be characterized at 15 kVacc. Fluorescence from metal-hosted elements will, however, contaminate silicate measurements, and this becomes problematic if the concentration contrast between the two phases is in excess of 100. Element partitioning experiments are potentially compromised; we recommend simulating fluorescence and applying a data correction, if required, to such DAC studies. Other spurious analyses may originate from sources external to the sample, as exemplified by 0.5 to >1 wt% of Cu arising from continuum fluorescence of the Cu TEM grid the sample is typically mounted on.

scholarly journals The niobium and tantalum concentration in the mantle constrains the composition of Earth’s primordial magma ocean

2020 ◽  
Vol 117 (45) ◽  
pp. 27893-27898
Author(s):  
Dongyang Huang ◽  
James Badro ◽  
Julien Siebert
Keyword(s):  
Diamond Anvil Cell ◽  
Magma Ocean ◽  
Core Formation ◽  
The Core ◽  
Bulk Silicate Earth ◽  
Reducing Conditions ◽  
Metal Silicate ◽  
Diamond Anvil ◽  
Laser Heated ◽  
Tantalum Concentration

The bulk silicate Earth (BSE), and all its sampleable reservoirs, have a subchondritic niobium-to-tantalum ratio (Nb/Ta). Because both elements are refractory, and Nb/Ta is fairly constant across chondrite groups, this can only be explained by a preferential sequestration of Nb relative to Ta in a hidden (unsampled) reservoir. Experiments have shown that Nb becomes more siderophile than Ta under very reducing conditions, leading the way for the accepted hypothesis that Earth’s core could have stripped sufficient amounts of Nb during its formation to account for the subchondritic signature of the BSE. Consequently, this suggestion has been used as an argument that Earth accreted and differentiated, for most of its history, under very reducing conditions. Here, we present a series of metal–silicate partitioning experiments of Nb and Ta in a laser-heated diamond anvil cell, at pressure and temperature conditions directly comparable to those of core formation; we find that Nb is more siderophile than Ta under any conditions relevant to a deep magma ocean, confirming that BSE’s missing Nb is in the core. However, multistage core formation modeling only allows for moderately reducing or oxidizing accretionary conditions, ruling out the need for very reducing conditions, which lead to an overdepletion of Nb from the mantle (and a low Nb/Ta ratio) that is incompatible with geochemical observations. Earth’s primordial magma ocean cannot have contained less than 2% or more than 18% FeO since the onset of core formation.

scholarly journals The carbon content of Earth and its core

2020 ◽  
Vol 117 (16) ◽  
pp. 8743-8749 ◽  
Author(s):  
Rebecca A. Fischer ◽  
Elizabeth Cottrell ◽  
Erik Hauri ◽  
Kanani K. M. Lee ◽  
Marion Le Voyer
Keyword(s):  
Carbonaceous Chondrite ◽  
Magma Ocean ◽  
Core Formation ◽  
Earth’S Core ◽  
Multistage Model ◽  
Earth's Core ◽  
Metal Silicate ◽  
Diamond Anvil ◽  
Laser Heated ◽  
Carbon Inventory

Earth’s core is likely the largest reservoir of carbon (C) in the planet, but its C abundance has been poorly constrained because measurements of carbon’s preference for core versus mantle materials at the pressures and temperatures of core formation are lacking. Using metal–silicate partitioning experiments in a laser-heated diamond anvil cell, we show that carbon becomes significantly less siderophile as pressures and temperatures increase to those expected in a deep magma ocean during formation of Earth’s core. Based on a multistage model of core formation, the core likely contains a maximum of 0.09(4) to 0.20(10) wt% C, making carbon a negligible contributor to the core’s composition and density. However, this accounts for ∼80 to 90% of Earth’s overall carbon inventory, which totals 370(150) to 740(370) ppm. The bulk Earth’s carbon/sulfur ratio is best explained by the delivery of most of Earth’s volatiles from carbonaceous chondrite-like precursors.

scholarly journals Reconciling metal–silicate partitioning and late accretion in the Earth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Terry-Ann Suer ◽  
Julien Siebert ◽  
Laurent Remusat ◽  
James M. D. Day ◽  
Stephan Borensztajn ◽  
...  
Keyword(s):  
High Pressures ◽  
Platinum Metal ◽  
Core Formation ◽  
Enriched Mantle ◽  
Metal Silicate ◽  
Partitioning Coefficients ◽  
Diamond Anvil ◽  
Laser Heated ◽  
Geochemical Constraints ◽  
Island Basalt

AbstractHighly siderophile elements (HSE), including platinum, provide powerful geochemical tools for studying planet formation. Late accretion of chondritic components to Earth after core formation has been invoked as the main source of mantle HSE. However, core formation could also have contributed to the mantle’s HSE content. Here we present measurements of platinum metal-silicate partitioning coefficients, obtained from laser-heated diamond anvil cell experiments, which demonstrate that platinum partitioning into metal is lower at high pressures and temperatures. Consequently, the mantle was likely enriched in platinum immediately following core-mantle differentiation. Core formation models that incorporate these results and simultaneously account for collateral geochemical constraints, lead to excess platinum in the mantle. A subsequent process such as iron exsolution or sulfide segregation is therefore required to remove excess platinum and to explain the mantle’s modern HSE signature. A vestige of this platinum-enriched mantle can potentially account for 186Os-enriched ocean island basalt lavas.

scholarly journals An in situ approach to study trace element partitioning in the laser heated diamond anvil cell

2012 ◽  
Vol 83 (1) ◽  
pp. 013904 ◽  
Author(s):  
S. Petitgirard ◽  
M. Borchert ◽  
D. Andrault ◽  
K. Appel ◽  
M. Mezouar ◽  
...  
Keyword(s):  
Trace Element ◽  
Diamond Anvil Cell ◽  
Trace Element Partitioning ◽  
Element Partitioning ◽  
Diamond Anvil ◽  
Laser Heated

In situ synchrotron X-ray diffraction with laser-heated diamond anvil cells study of Pt up to 95 GPa and 3150 K

RSC Advances ◽  
2015 ◽  
Vol 5 (19) ◽  
pp. 14603-14609 ◽  
Author(s):  
Xiaoli Huang ◽  
Fangfei Li ◽  
Qiang Zhou ◽  
Gang Wu ◽  
Yanping Huang ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Diamond Anvil Cells ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

In situ synchrotron X-ray diffraction with laser-heated diamond anvil cells study the EOS of Pt.

scholarly journals Synthesis of InSb in a Laser Heated Diamond Anvil Cell.

1998 ◽  
Vol 7 ◽  
pp. 1019-1021 ◽  
Author(s):  
N. V. Chandra Shekar ◽  
K. Takemura ◽  
H. Yusa
Keyword(s):  
Diamond Anvil Cell ◽  
Diamond Anvil ◽  
Laser Heated

Construction of laser-heated diamond anvil cell system for in situ x-ray diffraction study at SPring-8

2001 ◽  
Vol 72 (2) ◽  
pp. 1289 ◽  
Author(s):  
Tetsu Watanuki ◽  
Osamu Shimomura ◽  
Takehiko Yagi ◽  
Tadashi Kondo ◽  
Maiko Isshiki
Keyword(s):  
Diffraction Study ◽  
Diamond Anvil Cell ◽  
Cell System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

scholarly journals Melting of iron determined by X-ray absorption spectroscopy to 100 GPa

2015 ◽  
Vol 112 (39) ◽  
pp. 12042-12045 ◽  
Author(s):  
Giuliana Aquilanti ◽  
Angela Trapananti ◽  
Amol Karandikar ◽  
Innokenty Kantor ◽  
Carlo Marini ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Absorption Spectroscopy ◽  
Inner Core ◽  
Solid Phase ◽  
Melting Curve ◽  
X Ray ◽  
Core Boundary ◽  
Diamond Anvil ◽  
Laser Heated ◽  
X Ray Absorption

Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa.

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