Osmium isotope and highly siderophile element systematics of lunar impact melt breccias: Implications for the late accretion history of the Moon and Earth

Puchtel, I. S.; Walker, Richard J.; James, O. B.; Kring, D. A.

doi:10.1016/j.gca.2008.04.006

Cited by 103 publications

(112 citation statements)

References 61 publications

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“…The slopes of the linear trends can, therefore, be assumed to record the HSE ratios of the basin forming impactors. Puchtel et al (2008) and Sharp et al (2014) (2012), thus, strengthening their observation. In the compilation of data reported by Liu et al (2015), nearly all data for lunar impact melt rocks plot along a continuous linear trend ranging from a HSE composition that is broadly chondritic, to an endmember with 187 Os/ 188 Os, Ru/Ir and Pd/Ir ratios far above those of known chondrites (Fig.…”

Section: Accepted Manuscriptmentioning

confidence: 56%

In search of late-stage planetary building blocks

et al. 2015

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Section: Accepted Manuscriptmentioning

confidence: 56%

In search of late-stage planetary building blocks

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“…Because of the proportionally large relative uncertainties in Re blank contributions (e.g., ∼11-76% variation in Re for TPB), the value Re * is also reported; this is the concentration of Re calculated assuming chondritic 187 Os/ 188 Os at the assumed time of sample crystallization. External reproducibility of measurements were also monitored by regular analysis of diluted and concentrated reference materials (Allende, UB-N, HARZ-01, GP-13) in the UMd laboratory (see Walker et al, 2004;Puchtel et al, 2008;Day et al, 2012).…”

Section: Methodsmentioning

confidence: 99%

“…This is because prior studies have shown that the upper portions of the lunar crust, especially regolith, are enriched in chondritic impactor debris (Gros et al, 1976;Hertogen et al, 1977;Korotev, 1987;Warren et al, 1989;Norman et al, 2002;Puchtel et al, 2008;Fischer-Gödde and Becker, 2012), coupled with the fact that chondrites have high HSE contents (Horan et al, 2003;Fischer-Gödde et al, 2010). Consequently, HSE contamination must be considered for any mare basalts potentially extruded onto HSE-rich regolith.…”

Section: Regolith Contaminationmentioning

confidence: 99%

“…Due to propagated uncertainties in Re/Os, the model uses present-day 187 Os/ 188 Os and assumes a modestly radiogenic 187 Os/ 188 Os of putative mantle melts of 0.22. For the very low initial Os content, the mixing calculations show that Os , lunar impact-melt breccias (LIMB; Puchtel et al, 2008) and chondrites (Horan et al, 2003). The curve shows mixing between a hypothetical mare basalt parental melt composition with very low Os ( 187 Os/ 188 Os −∼0.22; Os = 1 pgg −1 ) and low Os (10 pg g −1 ) and a regolith composition with ∼1% chondritic contamination ( 187 Os/ 188 Os = 0.1275; Os = 10,000 pg g −1 ).…”

Section: Regolith Contaminationmentioning

confidence: 99%

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Highly siderophile element depletion in the Moon

Day

Walker

2015

Earth and Planetary Science Letters

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70135) mare basalts, along with mare basalt meteorites La Paz icefield (LAP) 04841 and Miller Range (MIL) 05035. These mare basalts have consistently low HSE abundances, at ∼2 × 10 −5 to 2 × 10 −7 the chondritic abundance. The most magnesian samples have broadly chondrite-relative HSE abundances and chondritic measured and calculated initial 187 Os/ 188 Os. The lower abundances and fractionated HSE compositions of more evolved mare basalts can be reproduced by modeling crystalliquid fractionation using rock/melt bulk-partition coefficients of ∼2 for Os, Ir, Ru, Pt and Pd and ∼1.5 for Re. Lunar mare basalt bulk-partition coefficients are probably higher than for terrestrial melts as a result of more reducing conditions, leading to increased HSE compatibility. The chondritic-relative abundances and chondritic 187 Os/ 188 Os of the most primitive high-MgO mare basalts cannot readily be explained through regolith contamination during emplacement at the lunar surface. Mare basalt compositions are best modeled as representing ∼5-11% partial melting of metal-free sources with low Os, Ir, Ru, Pd (∼0.1 ng g −1 ), Pt (∼0.2 ng g −1 ), Re (∼0.01 ng g −1 ) and S (∼75 μg g −1 ), with sulphide-melt partitioning between 1000 and 10,000. Apollo 12 olivine-, pigeonite-and ilmenite normative mare basalts define an imprecise 187 Re-187 Os age of 3.0 ± 0.9 Ga with an initial 187 Os/ 188 Os of 0.107 ± 0.010. This age is within uncertainty of 147 Sm-143 Nd ages for the samples. The initial Os isotopic composition of Apollo 12 samples indicates that the source of these rocks evolved with Re/Os within ∼10% of chondrite meteorites, from the time that the mantle source became a system closed to siderophile additions, to the time that the basalts erupted. Similarity in absolute HSE abundances between mare basalts from the Apollo 12, 15 and 17 sites, and from unknown regions of the Moon (La Paz mare basalts, MIL 05035), indicates relatively homogeneous and low HSE abundances within the lunar interior. Low absolute HSE abundances and chondritic Re/Os of mare basalts are consistent with a late accretion addition of ∼0.02 wt.% of the Moon's mass to the mantle, prior to the formation of the lunar crust. Late accretion must also have occurred significantly prior to cessation of lunar mantle differentiation (>4.4 Ga), to enable efficient mixing and homogenization within the mantle. Low lunar HSE abundances are consistent with proportionally 40 times more late accretion to Earth than the Moon. Disproportional late accretion to the two bodies is consistent with the small 182 W excess (∼21-28 ppm) measured in lunar rocks, compared to the silicate Earth.

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“…Kring and Cohen 2002 and references therein; Strom et al 2005;Puchtel et al 2008;Joy et al 2012;Marchi et al 2012;, and provides critical constraints to models of the Solar System's dynamical environment. A wide variety of these theoretical models have emerged since the early proposals of Wetherill (1975), and these are constantly being developed and refined as new lunar samples and geological data becomes available.…”

Section: Introductionmentioning

confidence: 99%

The Moon: An Archive of Small Body Migration in the Solar System

et al. 2016

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The Moon is an archive of impact cratering in the Solar System throughout the past 4.5 billion years. It preserves this record better than larger, more complex planets like the Earth, Mars and Venus, which have largely lost their ancient crusts through geological reprocessing and hydrospheric/atmospheric weathering. Identifying the parent bodies of impactors (i.e. asteroid bodies, comets from the Kuiper belt or the Oort Cloud) provides geochemical and chronological constraints for models of Solar System dynamics, helping to better inform our wider understanding of the evolution of the Solar System and the transfer of small bodies between planets. In this review article, we discuss the evidence for populations of impactors delivered to the Moon at different times in the past. We also propose approaches to the identification and characterisation of meteoritic material on the Moon in the context of future lunar exploration efforts.

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Osmium isotope and highly siderophile element systematics of lunar impact melt breccias: Implications for the late accretion history of the Moon and Earth

Cited by 103 publications

References 61 publications

In search of late-stage planetary building blocks

In search of late-stage planetary building blocks

Highly siderophile element depletion in the Moon

The Moon: An Archive of Small Body Migration in the Solar System

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