Late accretion history of the terrestrial planets inferred from platinum stable isotopes

Creech, J.; Baker, Joel J.A.; Handler, Monica R.; Lorand, Jean‐Pierre; Storey, Michael; Wainwright, Ashlea N.; Luguet, Ambre; Moynier, Frédéric; Bizzarro, Martin

doi:10.7185/geochemlet.1710

Cited by 29 publications

(27 citation statements)

References 8 publications

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“…The results thus not only provide support for models that require elevated atmospheric pCO 2 to compensate for the faint young sun 30 but also have significant implications for continental emergence/weathering through time 31 , 32 . Although our data do not definitively prove the existence of a global network of interconnected plate boundaries (as required by some definitions of “plate tectonics”), we show that subduction events occurred repeatedly throughout the Archean, in agreement with a growing body of evidence suggesting that plate-tectonic processes started prior to 3.5 Ga 1 , 6 , 9 , 10 , 20 , 31 – 34 .…”

Section: Resultssupporting

confidence: 64%

Calcium isotope evidence for early Archaean carbonates and subduction of oceanic crust

et al. 2021

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Continents are unique to Earth and played a role in coevolution of the atmosphere, hydrosphere, and biosphere. Debate exists, however, regarding continent formation and the onset of subduction-driven plate tectonics. We present Ca isotope and trace-element data from modern and ancient (4.0 to 2.8 Ga) granitoids and phase equilibrium models indicating that Ca isotope fractionations are dominantly controlled by geothermal gradients. The results require gradients of 500–750 °C/GPa, as found in modern (hot) subduction-zones and consistent with the operation of subduction throughout the Archaean. Two granitoids from the Nuvvuagittuq Supracrustal Belt, Canada, however, cannot be explained through magmatic processes. Their isotopic signatures were likely inherited from carbonate sediments. These samples (> 3.8 Ga) predate the oldest known carbonates preserved in the rock record and confirm that carbonate precipitation in Eoarchaean oceans provided an important sink for atmospheric CO2. Our results suggest that subduction-driven plate tectonic processes started prior to ~3.8 Ga.

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Section: Resultssupporting

confidence: 64%

Calcium isotope evidence for early Archaean carbonates and subduction of oceanic crust

et al. 2021

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“…Mass‐dependent isotope analyses may help to constrain terrestrial core formation and the late addition of extra‐terrestrial materials to the Earth's mantle (Creech et al . ). Moreover, stable Pt isotope techniques may also be applied as a redox tracer in marine environments, as environmental monitors of vehicle emissions (Creech et al .…”

Section: Relative Abundance Nucleosynthetic Production Sites and Majmentioning

confidence: 97%

Separation of Platinum from Palladium and Iridium in Iron Meteorites and Accurate High‐Precision Determination of Platinum Isotopes by Multi‐Collector ICP‐MS

Hunt

Schönbächler

2017

Geostandard Geoanalytic Res

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This study presents a new measurement procedure for the isolation of Pt from iron meteorite samples. The method also allows for the separation of Pd from the same sample aliquot. The separation entails a two‐stage anion‐exchange procedure. In the first stage, Pt and Pd are separated from each other and from major matrix constituents including Fe and Ni. In the second stage, Ir is reduced with ascorbic acid and eluted from the column before Pt collection. Platinum yields for the total procedure were typically 50–70%. After purification, high‐precision Pt isotope determinations were performed by multi‐collector ICP‐MS. The precision of the new method was assessed using the IIAB iron meteorite North Chile. Replicate analyses of multiple digestions of this material yielded an intermediate precision for the measurement results of 0.73 for ε192Pt, 0.15 for ε194Pt and 0.09 for ε196Pt (2 standard deviations). The NIST SRM 3140 Pt solution reference material was passed through the measurement procedure and yielded an isotopic composition that is identical to the unprocessed Pt reference material. This indicates that the new technique is unbiased within the limit of the estimated uncertainties. Data for three iron meteorites support that Pt isotope variations in these samples are due to exposure to galactic cosmic rays in space.

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“…Further, late accretion may have been dominated by the impact of several large projectiles (2500 -3000 km in diameter) stochastically delivered and emulsified into the BSE (Bottke et al, 2010;Dahl and Stevenson, 2010). Recent studies based on N body simulations and Pt isotope constraints support the contention that late accretion played a dominant role in establishing the abundances of HSE in the mantle (Rubie et al, 2016;Creech et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

The ruthenium isotopic composition of the oceanic mantle

Bermingham

Walker

2017

Earth and Planetary Science Letters

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The approximately chondritic relative, and comparatively high absolute m antle abundances of the highly siderophile elem ents (HSE), suggest that their concentrations in the bulk silicate Earth were primarily established during a final ~0.5 to 1% of "late accretion" to the mantle, following the cessation of core segregation. Consequently, the isotopic composition of the HSE Ru in the mantle reflects an amalgamation of the isotopic compositions of late accretionary contributions to the silicate portion of the Earth. Among cosm ochem ical materials, Ru is characterized by considerable mass-independent isotopic variability, making it a powerful genetic tracer of Earth's late accretionary building blocks. To define the Ru isotopic composition of the oceanic mantle, the largest portion of the accessible mantle, we report Ru isotopic data for materials from one Archean and seven Phanerozoic oceanic m antle domains. A sample from a continental lithospheric mantle domain is also examined. All samples have identical Ru isotopic compositions, within analytical uncertainties, indicating that Ru isotopes are well mixed in the oceanic mantle, defining a μ 100 Ru value of 1.2 ± 7.2 (2SD). The only known meteorites with the same Ru isotopic composition are enstatite chondrites and, when corrected for the effects of cosmic ray exposure, mem bers of the Main Group and sLL subgroup of the lAB iron meteorite complex which have a collective CRE corrected μ 100 Ru value of 0.9 ± 3.0. This suggests that materials from the region(s) of the solar nebula sampled by these m eteorites likely contributed the dominant portion of late accreted materials to Earth's mantle.

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Late accretion history of the terrestrial planets inferred from platinum stable isotopes

Cited by 29 publications

References 8 publications

Calcium isotope evidence for early Archaean carbonates and subduction of oceanic crust

Calcium isotope evidence for early Archaean carbonates and subduction of oceanic crust

Separation of Platinum from Palladium and Iridium in Iron Meteorites and Accurate High‐Precision Determination of Platinum Isotopes by Multi‐Collector ICP‐MS

The ruthenium isotopic composition of the oceanic mantle

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