The great isotopic dichotomy of the early Solar System

The Astrophysical Journal

The fundamentally different isotopic compositions of non-carbonaceous (NC) and carbonaceous (CC) meteorites reveal the presence of two distinct reservoirs in the solar protoplanetary disk that were likely separated by Jupiter. However, the extent of material exchange between these reservoirs, and how this affected the composition of the inner disk, are not known. Here we show that NC meteorites display broadly correlated isotopic variations for Mo, Ti, Cr, and Ni, indicating the addition of isotopically distinct material to the inner disk. The added material resembles bulk CC meteorites and Ca-Al-rich inclusions in terms of its enrichment in neutron-rich isotopes, but unlike the latter materials is also enriched in s-process nuclides. The comparison of the isotopic composition of NC meteorites with the accretion ages of their parent bodies reveals that the isotopic variations within the inner disk do not reflect a continuous compositional change through the addition of CC dust, indicating an efficient separation of the NC and CC reservoirs and limited exchange of material between the inner and outer disk. Instead, the isotopic variations among NC meteorites more likely record a rapidly changing composition of the disk during infall from the Sun's parental molecular cloud, where each planetesimal locks the instant composition of the disk when it forms. A corollary of this model is that late-formed planetesimals in the inner disk predominantly accreted from secondary dust that was produced by collisions among pre-existing NC planetesimals.

Nature, 2018

Nucleosynthetic isotope variability among Solar System objects is often used to probe the genetic relationship between meteorite groups and the rocky planets (Mercury, Venus, Earth and Mars), which, in turn, may provide insights into the building blocks of the Earth-Moon system. Using this approach, it has been inferred that no primitive meteorite matches the terrestrial composition and the protoplanetary disk material from which Earth and the Moon accreted is therefore largely unconstrained. This conclusion, however, is based on the assumption that the observed nucleosynthetic variability of inner-Solar-System objects predominantly reflects spatial heterogeneity. Here we use the isotopic composition of the refractory element calcium to show that the nucleosynthetic variability in the inner Solar System primarily reflects a rapid change in the mass-independent calcium isotope composition of protoplanetary disk solids associated with early mass accretion to the proto-Sun. We measure ...

Origin of the Solar System, 1963

The matsrlal in this chapter.is drawn in pax7t from two papers by. the author (~nders 1962, 1963). . , inevitable in such a.long extrapolation. Given,this di,fference in models, even a simple observation, such as' the fact that the iron meteorites were once molten, may. occasionally. lead to . . radically. different interpretations. . Ringwood (1959), Lovering. (1957), and Wood (1958) assumed that the melting was caused by 238 40 ~h ~~~, u~~~ , and U ) ; Urey long-lived radioactivities (K , attributed' it to chemical r~eactioizs among thermodyr~arriically unstable cunipounds (~rey and Donn, 1956) or adiabatic compression of gases (~rey. 1962a); and Fish, Goles, and Anders (lg60"), . . followj.ng an earlier suggestion by. Urey. (19551, proposed that 26 extinct radioactivities, specifically 740,000-year ~l , wenle responsible for the melting. Not many. properties of meteorites, however well established, permit-only. a single, unambiguous interpretati-on. Hence, the most one can deriiand of arly theory. of the origin of the solar system is that it be compatible with the primary. properties of the meteorites, and with those secondary deductions on which a consensus exists. . . , .

Nature, 1983

Planetary and Space Science, 2012

The evolution of planets is driven by the composition, structure, and thermal state of their internal core, mantle, lithosphere, and crust, and by interactions with a possible ocean and/or atmosphere. A planet's history is a long chronology of events with possibly a sequence of apocalyptic events in which asteroids, comets and their meteorite offspring play an important role. Large meteorite impacts on the young Earth could have contributed to the conditions for life to appear, and similarly large meteorite impacts could also create the conditions to erase life or drastically decrease biodiversity on the surface of the planet. Meteorites also contain valuable information to understand the evolution of a planet through their gas inclusion, their composition, and their cosmogenic isotopes. This paper addresses the evolution of the terrestrial bodies of our Solar System, in particular through all phenomena related to meteorites and what we can learn from them. This includes our present understanding of planet formation, their interior, their atmosphere, and the effects and relations of meteorites with respect to these reservoirs. It brings further insight into the origin and sustainability of life on planets, including Earth. Particular attention is devoted to Earth and Mars, as well as to planets and satellites possessing an atmosphere (Earth, Mars, Venus, and Titan) or a subsurface ocean (e.g., Europa), because those are the best candidates for hosting life. Though the conditions on the planets Earth, Mars, and Venus were probably similar soon after their formation, their histories have diverged about 4 billion years ago. The search for traces of life on early Earth serves as a case study to refine techniques/environments allowing the detection of potential habitats and possible life on other planets. A strong emphasis is placed on impact processes, an obvious shaper of planetary evolution, and on meteorites that document early Solar System evolution and witness the geological processes taking place on other planetary bodies.

Meteoritics & Planetary Science, 2008

Little is known about the stellar environment and the genealogy of our solar system. Short-lived radionuclides (SLRs, mean lifetime τ shorter than 100 Myr) that were present in the solar protoplanetary disk 4.56 Gyr ago could potentially provide insight into that key aspect of our history, were their origin understood. Aims. Previous models failed to provide a reasonable explanation of the abundance of two key SLRs, 26 Al (τ 26 = 1.1 Myr) and 60 Fe (τ 60 = 3.7 Myr), at the birth of the solar system by requiring unlikely astrophysical conditions. Our aim is to propose a coherent and generic solution based on the most recent understanding of star-forming mechanisms.

Science, 2001

... 0.9 Ma, within 0 to 4 Ma of CAI formation (36). Hf-W dating of iron meteorites also points to rapid differentiation of their parent bodies (<5 to 15 Ma after CAIs) (45). The age limits set by these different meteorites are all consistent ...

The Astrophysical Journal, 2007

CITATIONS 77 READS 73 2 authors: Some of the authors of this publication are also working on these related projects:

Protostars and Planets VI, 2014

Radioisotopic ages for meteorites and their components provide constraints on the evolution of small bodies: timescales of accretion, thermal and aqueous metamorphism, differentiation, cooling and impact metamorphism. Realising that the decay heat of short-lived nuclides (e.g. 26 Al, 60 Fe), was the main heat source driving differentiation and metamorphism, thermal modeling of small bodies is of utmost importance to set individual meteorite age data into the general context of the thermal evolution of their parent bodies, and to derive general conclusions about the nature of planetary building blocks in the early solar system. As a general result, modelling easily explains that iron meteorites are older than chondrites, as early formed planetesimals experienced a higher concentration of short-lived nuclides and more severe heating. However, core formation processes may also extend to 10 Ma after formation of Calcium-Aluminum-rich inclusions (CAIs). A general effect of the porous nature of the starting material is that relatively small bodies (< few km) will also differentiate if they form within 2 Ma after CAIs. A particular interesting feature to be explored is the possibility that some chondrites may derive from the outer undifferentiated layers of asteroids that are differentiated in their interiors. This could explain the presence of remnant magnetization in some chondrites due to a planetary magnetic field.