Heiny Elizabeth A, Stolper Edward M, Eiler John M
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
Proc Natl Acad Sci U S A. 2025 May 6;122(18):e2418198122. doi: 10.1073/pnas.2418198122. Epub 2025 May 2.
The isotope anomalies of noncarbonaceous (NC) and carbonaceous (CC) extraterrestrial materials provide a framework for tracing the distribution and accretion of matter in the early solar system. Here, we extend this framework to sulfur (S)-one of six "life-essential" volatile elements [T ~ 664 K]-via the mass-independent S-isotope compositions of differentiated meteorites. We observe that on average, NC and CC iron meteorites are characterized by distinct ΔS (ΔS = 0.013 ± 0.003‰; ΔS = -0.021 ± 0.009‰; 2 SE). The average ΔS of NC and CC irons are less well resolved (ΔS = -0.006 ± 0.039‰; ΔS = -0.101 ± 0.114‰; 2 SE), but the ΔS values of the CC irons are concentrated in the lower half of the range of those observed for iron meteorites. A lack of CC achondrite S-isotope analyses prevents direct comparison of the ΔS and ΔS of NC and CC achondrites, but the average ΔS and ΔS of NC achondrites (ΔS = 0.02 ± 0.008; ΔS = -0.019 ± 0.064‰; 2 SE) overlap with those of the NC irons. The average ΔS values of NC achondrite groups also correlate with nucleosynthetic anomalies of other elements (e.g., Cr) previously used to define isotopic heterogeneity within the NC reservoir. The position of the Earth in ΔS-ΔS composition space implies that 24% of terrestrial S derives from CC materials, while the majority (76%) was delivered by NC materials.
非碳质（NC）和碳质（CC）地外物质的同位素异常为追溯早期太阳系中物质的分布和吸积提供了一个框架。在此，我们通过分异陨石的质量无关硫（S）同位素组成，将这个框架扩展到硫（S）——六种“生命必需”挥发性元素之一[温度~664K]。我们观察到，平均而言，NC和CC铁陨石具有明显不同的Δ³³S（Δ³³S = 0.013±0.003‰；Δ³³S = -0.021±0.009‰；2倍标准误差）。NC和CC铁陨石的平均Δ⁴⁴S分辨得较差（Δ⁴⁴S = -0.006±0.039‰；Δ⁴⁴S = -0.101±0.114‰；2倍标准误差），但CC铁陨石的Δ⁴⁴S值集中在铁陨石观测值范围的下半部分。由于缺乏CC无球粒陨石的S同位素分析，无法直接比较NC和CC无球粒陨石的Δ³³S和Δ⁴⁴S，但NC无球粒陨石的平均Δ³³S和Δ⁴⁴S（Δ³³S = 0.02±0.008；Δ⁴⁴S = -0.019±0.064‰；2倍标准误差）与NC铁陨石的重叠。NC无球粒陨石组的平均Δ³³S值也与先前用于定义NC储库内同位素非均一性的其他元素（如Cr）的核合成异常相关。地球在Δ³³S - Δ⁴⁴S组成空间中的位置表明，地球上约24%的硫来自CC物质，而大部分（约76%）是由NC物质输送的。
