scholarly journals Isotopic evolution of planetary crusts by hypervelocity impacts evidenced by Fe in microtektites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. M. Chernonozhkin ◽  
C. González de Vega ◽  
N. Artemieva ◽  
B. Soens ◽  
J. Belza ◽  
...  
Keyword(s):  
Solar System ◽  
Isotopic Fractionation ◽  
Exact Nature ◽  
Volatile Elements ◽  
Hypervelocity Impacts ◽  
Evaporation And Condensation ◽  
Impact Ejecta ◽  
Isotopic Evolution ◽  
Impact Heating ◽  
Impact Events

AbstractFractionation effects related to evaporation and condensation had a major impact on the current elemental and isotopic composition of the Solar System. Although isotopic fractionation of moderately volatile elements has been observed in tektites due to impact heating, the exact nature of the processes taking place during hypervelocity impacts remains poorly understood. By studying Fe in microtektites, here we show that impact events do not simply lead to melting, melt expulsion and evaporation, but involve a convoluted sequence of processes including condensation, variable degrees of mixing between isotopically distinct reservoirs and ablative evaporation during atmospheric re-entry. Hypervelocity impacts can as such not only generate isotopically heavy, but also isotopically light ejecta, with δ56/54Fe spanning over nearly 5‰ and likely even larger variations for more volatile elements. The mechanisms demonstrated here for terrestrial impact ejecta modify our understanding of the effects of impact processing on the isotopic evolution of planetary crusts.

Carbonaceous chondrite meteorites experienced fluid flow within the past million years

Science ◽  
2021 ◽  
Vol 371 (6525) ◽  
pp. 164-167
Author(s):  
Simon Turner ◽  
Lucy McGee ◽  
Munir Humayun ◽  
John Creech ◽  
Brigitte Zanda
Keyword(s):  
Fluid Flow ◽  
Solar System ◽  
Cosmic Ray ◽  
Parent Body ◽  
Uranium Isotopes ◽  
The Past ◽  
Uranium Ion ◽  
Impact Heating ◽  
The Impact ◽  
Cosmic Ray Exposure Age

Carbonaceous chondritic meteorites are primordial Solar System materials and a source of water delivery to Earth. Fluid flow on the parent bodies of these meteorites is known to have occurred very early in Solar System history (first <4 million years). We analyze short-lived uranium isotopes in carbonaceous chondrites, finding excesses of 234-uranium over 238-uranium and 238-uranium over 230-thorium. These indicate that the fluid-mobile uranium ion U6+ moved within the past few 100,000 years. In some meteorites, this time scale is less than the cosmic-ray exposure age, which measures when they were ejected from their parent body into space. Fluid flow occurred after melting of ice, potentially by impact heating, solar heating, or atmospheric ablation. We favor the impact heating hypothesis, which implies that the parent bodies still contain ice.

scholarly journals Erosive Hit-and-Run Impact Events: Debris Unbound

2015 ◽  
Vol 10 (S318) ◽  
pp. 9-15
Author(s):  
Gal Sarid ◽  
Sarah T. Stewart ◽  
Zoë M. Leinhardt
Keyword(s):  
Solar System ◽  
Asteroid Belt ◽  
Mass Composition ◽  
Residual Velocity ◽  
Processed Material ◽  
Planetary Bodies ◽  
Hit And Run ◽  
Main Asteroid Belt ◽  
Impact Events

AbstractErosive collisions among planetary embryos in the inner solar system can lead to multiple remnant bodies, varied in mass, composition and residual velocity. Some of the smaller, unbound debris may become available to seed the main asteroid belt. The makeup of these collisionally produced bodies is different from the canonical chondritic composition, in terms of rock/iron ratio and may contain further shock-processed material. Having some of the material in the asteroid belt owe its origin from collisions of larger planetary bodies may help in explaining some of the diversity and oddities in composition of different asteroid groups.

Stochastic accretion of the Earth

2020 ◽  
Author(s):  
Paolo Sossi ◽  
Ingo Stotz ◽  
Seth Jacobson ◽  
Alessandro Morbidelli ◽  
Hugh O'Neill
Keyword(s):  
Building Blocks ◽  
Physical Processes ◽  
Volatile Elements ◽  
Volatile Element ◽  
Elemental Abundances ◽  
Stable Isotope Fractionation ◽  
The Earth ◽  
Gravitational Pull ◽  
Atmospheric Loss ◽  
Impact Events

&lt;p&gt;The Earth is depleted in volatile elements relative to chondritic meteorites, its possible building blocks. Abundances of volatile elements descend roughly log-linearly with their calculated volatilities during solar nebula condensation [1, 2]. This depletion, however, is not accompanied by any stable isotope fractionation, which would otherwise be expected during vaporisation/condensation and atmospheric loss attending accretion [3, 4]. Thus, the physical processes that led to the formation of the Earth are yet to be reconciled with its chemical composition. Here, we integrate N-body simulations of planetary formation [5] within a framework that combines estimates for the compositions of planetary building blocks with volatile element losses during collisions, to link Earth&amp;#8217;s elemental- and isotopic make-up with accretion mechanisms. The smooth pattern of volatile depletion in the Earth reflects the stochastic accretion of numerous, smaller, partially-vaporised precursor bodies whose elemental abundances are set by the heliocentric distances at which they formed. Impact events engender vaporisation, but atmospheric loss is only efficient during the early stages of accretion when volatile species can readily escape the gravitational pull of the proto-Earth. The chemical and isotopic compositions of the most volatile elements are controlled by that of late-accreting material, during which time the proto-Earth is sufficiently large so as to limit atmospheric loss. Stable isotopes of moderately- and highly volatile elements thus retain near-chondritic compositions.&lt;/p&gt; &lt;p&gt;[1] O&amp;#8217;Neill and Palme (2008), &lt;em&gt;Phil. Trans. R. Soc.&lt;/em&gt; 4205-38 [2] Braukm&amp;#252;ller et al. (2019), &lt;em&gt;Nat. Geosci.&lt;/em&gt;, 564-9 [3] Wang and Jacobsen (2016), &lt;em&gt;Nature&lt;/em&gt;, 521-4 [4] Sossi et al. 2018, &lt;em&gt;Chem. Geol.&lt;/em&gt; 73-84 [5] Jacobson and Morbidelli (2014), &lt;em&gt;Phil. Trans. R. Soc.&lt;/em&gt; 20130174&lt;/p&gt;

scholarly journals Strong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula

2021 ◽  
Vol 7 (30) ◽  
pp. eabg7775
Author(s):  
Zijie Luo ◽  
Yarui Zhao ◽  
Zhichao Chen ◽  
Yao Chang ◽  
Su-e Zhang ◽  
...  
Keyword(s):  
Solar System ◽  
Isotope Effect ◽  
Quantum State ◽  
Solar Nebula ◽  
Isotopic Fractionation ◽  
Branching Ratios ◽  
Terrestrial Planets ◽  
Isotopic Ratios ◽  
Alternative Source ◽  
Photochemical Models

The deuterium versus hydrogen (D/H) isotopic ratios are important to understand the source of water on Earth and other terrestrial planets. However, the determinations of D/H ratios suggest a hydrogen isotopic diversity in the planetary objects of the solar system. Photochemistry has been suggested as one source of this isotope heterogeneity. Here, we have revealed the photodissociation features of the water isotopologue (HOD) at λ = 120.8 to 121.7 nm. The results show different quantum state populations of OH and OD fragments from HOD photodissociation, suggesting strong isotope effect. The branching ratios of H + OD and D + OH channels display large isotopic fractionation, with ratios of 0.70 ± 0.10 at 121.08 nm and 0.49 ± 0.10 at 121.6 nm. Because water is abundant in the solar nebula, photodissociation of HOD should be an alternative source of the D/H isotope heterogeneity. This isotope effect must be considered in the photochemical models.

scholarly journals Earth’s water may have been inherited from material similar to enstatite chondrite meteorites

Science ◽  
2020 ◽  
Vol 369 (6507) ◽  
pp. 1110-1113 ◽  
Author(s):  
Laurette Piani ◽  
Yves Marrocchi ◽  
Thomas Rigaudier ◽  
Lionel G. Vacher ◽  
Dorian Thomassin ◽  
...  
Keyword(s):  
Solar System ◽  
Isotopic Composition ◽  
Carbonaceous Chondrite ◽  
Earth’S Crust ◽  
Outer Solar System ◽  
Volatile Elements ◽  
Earth’S Mantle ◽  
Isotopic Compositions ◽  
Enstatite Chondrite ◽  
Earth's Crust

The origin of Earth’s water remains unknown. Enstatite chondrite (EC) meteorites have similar isotopic composition to terrestrial rocks and thus may be representative of the material that formed Earth. ECs are presumed to be devoid of water because they formed in the inner Solar System. Earth’s water is therefore generally attributed to the late addition of a small fraction of hydrated materials, such as carbonaceous chondrite meteorites, which originated in the outer Solar System where water was more abundant. We show that EC meteorites contain sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans. EC hydrogen and nitrogen isotopic compositions match those of Earth’s mantle, so EC-like asteroids might have contributed these volatile elements to Earth’s crust and mantle.

The Effects of Hyperbolic Meteoroids from Parker Solar Probe to the Moon

2020 ◽  
Author(s):  
Jamey Szalay ◽  
Petr Pokorny ◽  
Mihaly Horanyi ◽  
Stuart Bale ◽  
Eric Christian ◽  
...  
Keyword(s):  
Solar System ◽  
Solar Radiation ◽  
Radiation Pressure ◽  
Solar Radiation Pressure ◽  
The Sun ◽  
The Moon ◽  
Zodiacal Cloud ◽  
Impact Ejecta ◽  
Density Enhancement ◽  
Small Grains

&lt;p&gt;The zodiacal cloud in the inner solar system undergoes continual evolution, as its dust grains are collisionally ground and sublimated into smaller and smaller sizes. Sufficiently small (~&lt;500 nm) grains known as beta-meteoroids are ejected from the inner solar system on hyperbolic orbits under the influence of solar radiation pressure. These small grains can reach significantly larger speeds than those in the nominal zodiacal cloud and impact the surfaces of airless bodies. Since the discovery of the Moon's asymmetric ejecta cloud, the origin of its sunward-canted density enhancement has not been well understood. We propose impact ejecta from beta-meteoroids that hit the Moon's sunward side could explain this unresolved asymmetry. The proposed hypothesis rests on the fact that beta-meteoroids are one of the few truly asymmetric meteoroid sources in the solar system, as unbound grains always travel away from the Sun and lack a symmetric inbound counterpart. This finding suggests beta-meteoroids may also contribute to the evolution of other airless surfaces in the inner solar system as well as within other exo-zodiacal disks. We will also highlight recent observations from the Parker Solar Probe (PSP) spacecraft, which suggest it is being bombarded by the very same beta-meteoroids. We discuss how observations by PSP, which lacks a dedicated dust detector, can be used to inform the structure and variability of beta-meteoroids in the inner solar system closer to the Sun than ever before.&lt;/p&gt;

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