Solar system Nd isotope heterogeneity: Insights into nucleosynthetic components and protoplanetary disk evolution

Nikitha Susan Saji*, Daniel Wielandt, Jesper Christian Holst, Martin Bizzarro

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

17 Citations (Scopus)

Abstract

High-precision Nd isotope measurements of a diverse set of solar system materials including bulk chondrites and achondrites reveal that their Nd isotope composition is governed by several distinct nucleosynthetic components. The full spectrum of non-radiogenic, mass-independent Nd isotope compositions of solar system materials is best explained by heterogeneous distribution of at least three nucleosynthetic components - the classical s-process component, pure p-process component and an anomalous, previously unidentified s-/r-process component. The Nd-142/Nd-144 variations in solar system reservoirs specifically fall into three distinct trends - those that result from variations in the s-process component, those resulting from variations in the pure p-process component, and those resulting from coupled s-process and p-process variations. The mu Nd-148 value, a proxy for s-process variations, as well as mu Nd-142 that has been corrected for s-process heterogeneity to reflect p-process variations, broadly show an inverse correlation with epsilon Cr-54. The linearity in mu Nd-148 - epsilon Cr-54 space for inner solar system bodies, CI chondrite and Allende-type CAIs possibly suggests the thermally labile nature of some s-process carrier grains unlike the mainstream refractory s-process SiC grains. The p-process carrier for Nd is inferred to be a refractory phase enriched in inner solar system materials through thermal processing. The bulk meteorite regression lines that specifically correspond to s- and p-process heterogeneity, largely define mu Nd-142 intercepts indistinguishable from terrestrial composition within analytical uncertainty, ruling out resolvable radiogenic mu Nd-142 excess on Earth that cannot otherwise be accounted for by nucleosynthetic heterogeneity. (C) 2020 Elsevier Ltd. All rights reserved.

Original languageEnglish
JournalGeochimica et Cosmochimica Acta
Volume281
Pages (from-to)135-148
Number of pages14
ISSN0016-7037
DOIs
Publication statusPublished - 2020

Keywords

  • Nucleosynthentic anomalies
  • Neodymium-142
  • Chondrites
  • Bulk silicate Earth
  • Early solar system
  • GIANT BRANCH STARS
  • S-PROCESS
  • EARLY DIFFERENTIATION
  • NEUTRON-CAPTURE
  • BUILDING-BLOCKS
  • CROSS-SECTIONS
  • ND-142
  • EARTH
  • CHONDRITES
  • ANOMALIES

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