Partial melting of oxidized planetesimals: An experimental study to test the formation of oligoclase-rich achondrites Graves Nunataks 06128 and 06129

Lunning, N. G.; Gardner-Vandy, K. G.; Sosa, Emma S.; McCoy, Timothy J.; Bullock, E. S.; Corrigan, C. M.

doi:10.1016/j.gca.2017.07.004

Cited by 18 publications

(37 citation statements)

References 44 publications

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“…Their compositions resemble melt pockets (Fig. 2, 9), which were produced by in situ shock melting Rubin, 1985;Stöffler et al, 1991), as well as the compositions of partial melts in disequilibrium experiments (Feldstein et al, 2001;Lunning et al, 2017), although some of the melt pockets and experimental melts are more silicarich. None of the inclusions have the compositions one would expect of equilibrium partial melting.…”

Section: Fldr and Jgo-i1 Inclusionsmentioning

confidence: 78%

Petrology and oxygen isotopic composition of large igneous inclusions in ordinary chondrites: Early solar system igneous processes and oxygen reservoirs

Ruzicka

Greenwood

Armstrong

et al. 2019

Geochimica et Cosmochimica Acta

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Section: Fldr and Jgo-i1 Inclusionsmentioning

confidence: 78%

Petrology and oxygen isotopic composition of large igneous inclusions in ordinary chondrites: Early solar system igneous processes and oxygen reservoirs

Ruzicka

Greenwood

Armstrong

et al. 2019

Geochimica et Cosmochimica Acta

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“…If localized grain boundary conditions around the melt pools predominately controlled melt composition, we would expect greater variation between melt pools, as observed in endmember disequilibrium melting (e.g., Lunning et al. ). The major and minor element variations between melt in the experiments at 1075–1200 °C are also within the uncertainties of EMP analyses, which indicates the melt in these experiments is homogeneous in composition, and this is reflected in the trace element abundance variations.…”

Section: Discussionmentioning

confidence: 87%

“…) and sometimes even major element concentrations (Lunning et al. ) consistent with disequilibrium melting. The evidence presented here that Stannern‐trend eucrite formation by equilibrium partial melting of the eucritic crust highlights the complexity of the petrology of the HED parent body and the diversity of magmatic processes in the early solar system.…”

Section: Discussionmentioning

confidence: 92%

Experimental insights into Stannern‐trend eucrite petrogenesis

Crossley

Lunning

Mayne

et al. 2018

Meteorit & Planetary Scien

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The incompatible trace element‐enriched Stannern‐trend eucrites have long been recognized as requiring a distinct petrogenesis from the Main Group‐Nuevo Laredo (MGNL) eucrites. Barrat et al. () proposed that Stannern‐trend eucrites formed via assimilation of crustal partial melts by a MGNL‐trend magma. Previous experimental studies of low‐degree partial melting of eucrites did not produce sufficiently large melt pools for both major and trace element analyses. Low‐degree partial melts produced near the solidus are potentially the best analog to the assimilated crustal melts. We partially melted the unbrecciated, unequilibrated MGNL‐trend eucrite NWA 8562 in a 1 atm gas‐mixing furnace, at IW‐0.5, and at temperatures between 1050 and 1200 °C. We found that low‐degree partial melts formed at 1050 °C are incompatible trace element enriched, although the experimental melts did not reach equilibrium at all temperatures. Using our experimental melt compositions and binary mixing modeling, the FeO/MgO trend of the resultant magmas coincides with the range of known Stannern‐trend eucrites when a primary magma is contaminated by crustal partial melts. When experimental major element compositions for eucritic crustal partial melts are combined with trace element concentrations determined by previous modeling (Barrat et al. ), the Stannern‐trend can be replicated with respect to both major, minor, and trace element concentrations.

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“…This FeO-enrichment in their unequilibrated matrices reflects a higher intrinsic oxygen fugacity, which is reflected in more FeO-rich compositions for all olivine and pyroxene when equilibrated (Bischoff et al 2011). In addition, this higher intrinsic oxygen fugacity of R chondrites is reflected in higher Fe/Mn ratios in olivine and pyroxene in equilibrated R chondrites compared to those of other noncarbonaceous chondrites (Brearley and Jones 1998;Bischoff et al 2011;Lunning et al 2017;Miller et al 2017). Additionally, R chondrites are the only chondrite group that includes two distinct high-temperature metamorphic sequences (McCanta et al 2008;Bischoff et al 2011).…”

Section: Rumuruti Chondritesmentioning

confidence: 98%

“…Their high intrinsic oxygen fugacity made the anhydrous R chondrites (Righter and Neff 2007) a suitable analog to test the viability of forming the FeOrich, SiO 2 -rich achondrites Graves Nunataks 06128 and 06129 (GRA 06128/9) by disequilibrium fractional partial melting (Lunning et al 2017) although oxygen isotope compositions preclude a genetic relationship between GRA 06128/9 and R chondrites. GRA 06128/ 9 was the first identified achondrite with both an early solar system age (>4.5 Gyr) and a bulk composition more SiO 2 -rich than basalt (Shearer et al 2008(Shearer et al , 2010Day et al 2009aDay et al , 2009bDay et al , 2012Lindsay et al 2014;Zhou et al 2018); all previously recognized ancient achondrites are basaltic to ultramafic.…”

Section: Rumuruti Chondritesmentioning

confidence: 99%

Insights into the formation of silica‐rich achondrites from impact melts in Rumuruti‐type chondrites

Lunning

Bischoff

Groß

et al. 2019

Meteorit & Planetary Scien

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Ancient, SiO 2-rich achondrites have previously been proposed to have formed by disequilibrium partial melting of chondrites. Here, we test the alternative hypothesis that these achondrites formed by fractional crystallization of impact melts of Rumuruti (R) chondrites. We identified two new melt clasts in R chondrites, one in Pecora Escarpment (PCA) 91241 and one in LaPaz Icefield (LAP) 031275. We analyzed major, minor, and trace element concentrations, as well as oxygen isotopes, of these two clasts and a third one that had been previously recognized (Bischoff et al. 2011) as an impact melt in Dar al Gani (DaG) 013. The melt clast in PCA 91241 is an R chondrite impact melt closely resembling the one previously recognized in DaG 013. The melt clast in LAP 031275 has an L chondrite provenance. We show that SiO 2-rich melts could form from the mesostases of R chondrite impact melts. However, their CI-normalized rare earth element patterns are flat, whereas those of ancient SiO 2-rich achondrites (Day et al. 2012; Srinivasan et al. 2018) and those of disequilibrium partial melts of chondrites (Feldstein et al. 2001) have positive Eu anomalies from preferential melting of plagioclase. Thus, we conclude that ancient SiO 2-rich achondrites were probably formed by disequilibrium partial melting (due to an internal heat source on their parent bodies), rather than from impact melts. 132 N. G. Lunning et al.

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Partial melting of oxidized planetesimals: An experimental study to test the formation of oligoclase-rich achondrites Graves Nunataks 06128 and 06129

Cited by 18 publications

References 44 publications

Petrology and oxygen isotopic composition of large igneous inclusions in ordinary chondrites: Early solar system igneous processes and oxygen reservoirs

Petrology and oxygen isotopic composition of large igneous inclusions in ordinary chondrites: Early solar system igneous processes and oxygen reservoirs

Experimental insights into Stannern‐trend eucrite petrogenesis

Insights into the formation of silica‐rich achondrites from impact melts in Rumuruti‐type chondrites

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