Melting of the Indarch meteorite (EH4 chondrite) at 1GPa and variable oxygen fugacity: Implications for early planetary differentiation processes

Berthet, S.; Malavergne, Valérie; Righter, K.

doi:10.1016/j.gca.2009.07.030

Cited by 68 publications

(94 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…b K 2 O and Na 2 O calculated from Peplowski et al (2012Peplowski et al ( , 2014; TiO 2 and MnO contents based on Weider et al (2014). EH composition from Berthet et al (2009). c See details about the silicate-metal mixtures used in each experiment as well as the content of Si metal added to the starting material in Supplementary Dataset 1.…”

Section: Experiments Analytical Methods and Oxygen Fugacitymentioning

confidence: 99%

“…We considered a Na/Si ratio of 0.06 (∼2.7 wt.% Na 2 O) and 0.1 wt.% K 2 O. For the EH starting material, we used the silicate composition of the Indarch meteorite (McCoy et al, 1999;Berthet et al, 2009).…”

Section: Choice and Preparation Of Starting Compositionsmentioning

confidence: 99%

“…The intrinsic oxygen fugacity ( f O 2 ) of the samples was reduced by adding Si metal powder to the silicate starting material (Berthet et al, 2009;Cartier et al, 2014a;Malavergne et al, 2014). In most experiments, we varied the Si/SiO 2 ratio (0-0.5) in order to control f O 2 without affecting cation ratios of the starting compositions.…”

Section: Choice and Preparation Of Starting Compositionsmentioning

confidence: 99%

“…However, any interpretation of magmatic processes on Mercury and, in particular, the behavior of sulfur in magmas are presently very difficult because of the very limited number of experimental studies performed under oxygen fugacity conditions relevant to Mercury (McCoy et al, 1999;Berthet et al, 2009;Chabot et al, 2014;Malavergne et al, 2014;Vander Kaaden and McCubbin, 2016). In this study, we present the results of 100 new, high-temperature, low-to high-pressure (1 bar to 4 GPa), experiments performed under highly reducing conditions (IW-1.5 to .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Namur

Charlier

Holtz

et al. 2016

Earth and Planetary Science Letters

112

160

View full text Add to dashboard Cite

Chemical data from the MESSENGER spacecraft revealed that surface rocks on Mercury are unusually enriched in sulfur compared to samples from other terrestrial planets. In order to understand the speciation and distribution of sulfur on Mercury, we performed high temperature (1200-1750 • C), lowto high-pressure (1 bar to 4 GPa) experiments on compositions representative of Mercurian lavas and on the silicate composition of an enstatite chondrite. We equilibrated silicate melts with sulfide and metallic melts under highly reducing conditions (IW-1.5 to IW-9.4; IW = iron-wüstite oxygen fugacity buffer). Under these oxygen fugacity conditions, sulfur dissolves in the silicate melt as S 2− and forms complexes with Fe 2+ , Mg 2+ and Ca 2+ . The sulfur concentration in silicate melts at sulfide saturation (SCSS) increases with increasing reducing conditions (from <1 wt.% S at IW-2 to >10 wt.% S at IW-8) and with increasing temperature. Metallic melts have a low sulfur content which decreases from 3 wt.% at IW-2 to 0 wt.% at IW-9. We developed an empirical parameterization to predict SCSS in Mercurian magmas as a function of oxygen fugacity ( f O 2 ), temperature, pressure and silicate melt composition. SCSS being not strictly a redox reaction, our expression is fully valid for magmatic systems containing a metal phase. Using physical constraints of the Mercurian mantle and magmas as well as our experimental results, we suggest that basalts on Mercury were free of sulfide globules when they erupted. The high sulfur contents revealed by MESSENGER result from the high sulfur solubility in silicate melt at reducing conditions. We make the realistic assumption that the oxygen fugacity of mantle rocks was set during equilibration of the magma ocean with the core and/or that the mantle contains a minor metal phase and combine our parameterization of SCSS with chemical data from MESSENGER to constrain the oxygen fugacity of Mercury's interior to IW-5.4 ± 0.4. We also calculate that the mantle of Mercury contains 7-11 wt.% S and that the metallic core of the planet has little sulfur (<1.5 wt.% S). The external part of the Mercurian core is likely to be made up of a thin (<90 km) FeS layer.

show abstract

Section: Experiments Analytical Methods and Oxygen Fugacitymentioning

confidence: 99%

Section: Choice and Preparation Of Starting Compositionsmentioning

confidence: 99%

Section: Choice and Preparation Of Starting Compositionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Namur

Charlier

Holtz

et al. 2016

Earth and Planetary Science Letters

112

160

View full text Add to dashboard Cite

show abstract

“…However, under the reducing conditions that prevail on Mercury, estimated to be between 2.6 and 6.5 log units below the iron-wüstite buffer (Malavergne et al, 2010;Zolotov, 2011;McCubbin et al, 2012), iron occurs mainly as a metal phase or as a sulfide. Low-and high-pressure partial melting experiments at low fO 2 on the Indarch enstatite chondrite (McCoy et al, 1999;Berthet et al, 2009), a potential building block of Mercury (Wasson, 1988;Brown and Elkins-Tanton, 2009), have shown that immiscible metallic and sulfide melts are in equilibrium with the silicate melt. These iron and sulfide immiscible melts contain significant amounts of Si, Ca and Mg, showing that lithophile elements behave partly as siderophile and chalcophile elements under reducing conditions.…”

Section: Surface Compositions: Calculations and Assumptionsmentioning

confidence: 99%

Phase equilibria of ultramafic compositions on Mercury and the origin of the compositional dichotomy

Charlier

Grove

Zuber

2013

Earth and Planetary Science Letters

View full text Add to dashboard Cite

a b s t r a c tMeasurements of major element ratios obtained by the MESSENGER spacecraft using x-ray fluorescence spectra are used to calculate absolute element abundances of lavas at the surface of Mercury. We discuss calculation methods and assumptions that take into account the distribution of major elements between silicate, metal, and sulfide components and the potential occurrence of sulfide minerals under reduced conditions. These first compositional data, which represent large areas of mixed highreflectance volcanic plains and low-reflectance materials and do not include the northern volcanic plains, share common silica-and magnesium-rich characteristics. They are most similar to terrestrial volcanic rocks known as basaltic komatiites. Two compositional groups are distinguished by the presence or absence of a clinopyroxene component. Melting experiments at one atmosphere on the average compositions of each of the two groups constrain the potential mineralogy at Mercury's surface, which should be dominated by orthopyroxene (protoenstatite and orthoenstatite), plagioclase, minor olivine if any, clinopyroxene (augite), and tridymite. The two compositional groups cannot be related to each other by any fractional crystallization process, suggesting differentiated source compositions for the two components and implying multi-stage differentiation and remelting processes for Mercury. Comparison with high-pressure phase equilibria supports partial melting at pressure o10 kbar, in agreement with last equilibration of the melts close to the crust-mantle boundary with two different mantle lithologies (harzburgite and lherzolite). Magma ocean crystallization followed by adiabatic decompression of mantle layers during cumulate overturn and/or convection would have produced adequate conditions to explain surface compositions. The surface of Mercury is not an unmodified quenched crust of primordial bulk planetary composition. Ultramafic lavas from Mercury have high liquidus temperatures (1450-1350 1C) and very low viscosities, in accordance with the eruption style characterized by flooding of pre-existing impact craters by lava and absence of central volcanoes.

show abstract

Exotic crust formation on Mercury: Consequences of a shallow, FeO‐poor mantle

2015

View full text Add to dashboard Cite

The range in density and compressibility of Mercurian melt compositions was determined to better understand the products of a possible Mercurian magma ocean and subsequent volcanism. Our experiments indicate that the only mineral to remain buoyant with respect to melts of the Mercurian mantle is graphite; consequently, it is the only candidate mineral to have composed a primary floatation crust during a global magma ocean. This exotic result is further supported by Mercury's volatile-rich nature and inexplicably darkened surface. Additionally, our experiments illustrate that partial melts of the Mercurian mantle that compose the secondary crust were buoyant over the entire mantle depth and could have come from as deep as the core-mantle boundary. Furthermore, Mercury could have erupted higher percentages of its partial melts compared to other terrestrial planets because magmas would not have stalled during ascent due to gravitational forces. These findings stem from the FeO-poor composition and shallow depth of Mercury's mantle, which has resulted in both low-melt density and a very limited range in melt density responsible for Mercury's primary and secondary crusts. The enigmatically darkened, yet low-FeO surface, which is observed today, can be explained by secondary volcanism and impact processes that have since mixed the primary and secondary crustal materials.

show abstract

Melting of the Indarch meteorite (EH4 chondrite) at 1GPa and variable oxygen fugacity: Implications for early planetary differentiation processes

Cited by 68 publications

References 84 publications

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Phase equilibria of ultramafic compositions on Mercury and the origin of the compositional dichotomy

Exotic crust formation on Mercury: Consequences of a shallow, FeO‐poor mantle

Contact Info

Product

Resources

About