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 language | English |
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Journal | Geochimica et Cosmochimica Acta |
Volume | 281 |
Pages (from-to) | 135-148 |
Number of pages | 14 |
ISSN | 0016-7037 |
DOIs | |
Publication status | Published - 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