Highly Siderophile Elements in Earth, Mars, the Moon, and Asteroids

Day, James M.D.; Brandon, A. D.; Walker, Richard J.

doi:10.2138/rmg.2016.81.04

Cited by 136 publications

(111 citation statements)

References 220 publications

(547 reference statements)

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“…All of the initially accreted siderophiles would have been lost from the mantle. [78] Nevertheless, it is evident that the Earth's crust-mantle has gold and other siderophiles in what is called a "veneer". Their concentrations are much higher than expected if they had been delivered before core closure.…”

Section: Impacts Have the Potential To Deliver Large Amounts Of Reducmentioning

confidence: 99%

“…2016)). [78,80] These elements are believed to have arrived later, after the core became closed, via impacts of bodies too small to re-melt the Earth entirely and redifferentiate its constituents. [81] As extremes, the amounts of siderophiles observed in the mantle's veneer may have come from one larger impactor [82] or from many, many small impactors.…”

Section: Impacts Have the Potential To Deliver Large Amounts Of Reducmentioning

confidence: 99%

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When Did Life Likely Emerge on Earth in an RNA‐First Process?

et al. 2019

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The widespread presence of ribonucleic acid (RNA) catalysts and cofactors in the Earth′s biosphere today suggests that RNA was the first biopolymer to support Darwinian evolution. However, most “path‐hypotheses” to generate building blocks for RNA require reduced nitrogen‐containing compounds not made in useful amounts in the CO2−N2−H2O atmospheres of the Hadean. We review models for Earth′s impact history that invoke a single ∼1023 kg impactor (Moneta) to account for measured amounts of platinum, gold, and other siderophilic (“iron‐loving”) elements on the Earth and Moon. If it were the last sterilizing impactor, by reducing the atmosphere but not the mantle Moneta, would have opened a “window of opportunity” for RNA synthesis, a period when RNA precursors rained from the atmosphere onto land holding oxidized minerals that stabilize advanced RNA precursors and RNA. Surprisingly, this combination of physics, geology, and chemistry suggests a time when RNA formation was most probable, ∼120±100 million years after Moneta′s impact, or ∼4.36±0.1 billion years ago. Uncertainties in this time are driven by uncertainties in rates of productive atmosphere loss and amounts of sub‐aerial land.

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Section: Impacts Have the Potential To Deliver Large Amounts Of Reducmentioning

confidence: 99%

Section: Impacts Have the Potential To Deliver Large Amounts Of Reducmentioning

confidence: 99%

When Did Life Likely Emerge on Earth in an RNA‐First Process?

et al. 2019

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“…In addition, during mantle partial melting, Os behaves compatibly, whereas Re is moderately incompatible during mantle melting (e.g., Shirey and Walker 1998). This unique isotopic system has therefore been exploited to address a wide variety of geochemical and cosmochemical questions (Shirey and Walker 1998, Peucker-Ehrenbrink and Jahn 2001, Day et al 2010, 2016a, b, Harvey et al 2016, Lorand and Luguet 2016.…”

mentioning

confidence: 99%

Rhenium‐Osmium Isotope Measurements of Geological Reference Material BIR‐1a: Evaluation of Homogeneity and Implications for Method Validation and Quality Control

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Sun

et al. 2017

Geostandard Geoanalytic Res

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To evaluate the homogeneity of geological reference material BIR‐1a (basalt; United States Geological Survey, USGS) for Re‐Os isotopic studies at the 0.2–1.0 g test portion size level, sixty‐three precise measurement results of Re and Os mass fractions and isotope amount ratios were obtained over an 18‐month period. These data reveal that the reference material has higher Re (0.691 ± 0.022 ng g−1, 2s, n = 63) and lower Os mass fractions (0.343 ± 0.089 ng g−1, 2s, n = 63) than UB‐N (serpentinite, CRPG) and is homogeneous in 187Os/188Os isotope amount ratio (0.13371 ± 0.00092, 2s, n = 63) at the 0.2–1.0 g test portion size level. The results are essentially consistent with previous views indicating that BIR‐1a gives precise measurement results for Re‐Os isotope amount ratio measurements at the 1 g test portion size level (Ishikawa et al., Chemical Geology, 2014, 384, 27–46; Meisel and Horan, Reviews in Mineralogy and Geochemistry, 2016, 81, 89–106). Based on these new Re‐Os data and previous studies, we propose BIR‐1a as a useful reference material that can be used in method validation and quality control and interlaboratory comparisons for studies dealing with mafic geological samples at test portion sizes of > 0.4 g.

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“…The time interval has traditionally been defined as between lunar core segregation (determined by highly siderophile elements (HSE) partitioning into the lunar core; Dale et al 2012;Day et al 2016;Day and Walker 2015;Kruijer et al 2015) and the end of magma ocean solidification (which marks the point when the crust inhibited the addition of significant quantities of further exogenous material to the mantle). The time interval was dependent on the cooling rate of the Moon and is thought, on the basis of lunar sample ages, to have lasted until *200 Myr after lunar formation (Elkins-Tanton et al 2011).…”

Section: Late Accretionmentioning

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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Highly Siderophile Elements in Earth, Mars, the Moon, and Asteroids

Cited by 136 publications

References 220 publications

When Did Life Likely Emerge on Earth in an RNA‐First Process?

When Did Life Likely Emerge on Earth in an RNA‐First Process?

Rhenium‐Osmium Isotope Measurements of Geological Reference Material BIR‐1a: Evaluation of Homogeneity and Implications for Method Validation and Quality Control

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

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