TY - JOUR

T1 - Solar system Nd isotope heterogeneity

T2 - Insights into nucleosynthetic components and protoplanetary disk evolution

AU - Saji, Nikitha Susan

AU - Wielandt, Daniel

AU - Holst, Jesper Christian

AU - Bizzarro, Martin

PY - 2020

Y1 - 2020

N2 - 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.

AB - 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.

KW - Nucleosynthentic anomalies

KW - Neodymium-142

KW - Chondrites

KW - Bulk silicate Earth

KW - Early solar system

KW - GIANT BRANCH STARS

KW - S-PROCESS

KW - EARLY DIFFERENTIATION

KW - NEUTRON-CAPTURE

KW - BUILDING-BLOCKS

KW - CROSS-SECTIONS

KW - ND-142

KW - EARTH

KW - CHONDRITES

KW - ANOMALIES

U2 - 10.1016/j.gca.2020.05.006

DO - 10.1016/j.gca.2020.05.006

M3 - Journal article

VL - 281

SP - 135

EP - 148

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

ER -