The niobium-92–zirconium-92 (⁹²Nb–⁹²Zr) decay system with a half-life of 37 Ma has great potential to date the evolution of planetary materials in the early Solar System. Moreover, the initial abundance of the p-process isotope ⁹²Nb in the Solar System is important for quantifying the contribution of p-process nucleosynthesis in astrophysical models. Current estimates of the initial ⁹²Nb/⁹³Nb ratios have large uncertainties compromising the use of the ⁹²Nb–⁹²Zr cosmochronometer and leaving nucleosynthetic models poorly constrained. Here, the initial ⁹²Nb abundance is determined to high precision by combining the ⁹²Nb–⁹²Zr systematics of cogenetic rutiles and zircons from mesosiderites with U–Pb dating of the same zircons. The mineral pair indicates that the ⁹²Nb/⁹³Nb ratio of the Solar System started with (1.66 ± 0.10) × 10⁻⁵, and their ⁹²Zr/⁹⁰Zr ratios can be explained by a three-stage Nb–Zr evolution on the mesosiderite parent body. Because of the improvement by a factor of 6 of the precision of the initial Solar System ⁹²Nb/⁹³Nb, we can show that the presence of ⁹²Nb in the early Solar System provides further evidence that both type Ia supernovae and core-collapse supernovae contributed to the light p-process nuclei.

铌- 92 -锆-92（⁹² NB- ⁹² Zr）的衰减系统37 mA的半衰期有很大的潜力，迄今为止行星物料在早期太阳系的演化。此外，太阳过程中p过程同位素⁹² Nb的初始丰度对于定量天文学模型中p过程核合成的贡献很重要。当前对最初的⁹² Nb / ⁹³ Nb比率的估计存在很大的不确定性，这损害了使用⁹² Nb– ⁹² Zr天文钟的能力，并且使核合成模型的约束性很差。在这里，最初的⁹²通过将中生菱铁矿的共生金红石和锆石的⁹² Nb– ⁹² Zr系统与同一锆石的U–Pb测井相结合，可以高精度地确定Nb的丰度。矿物对表明，太阳系的⁹² Nb / ⁹³ Nb比率始于（1.66±0.10）×10 ^-5，而它们的⁹² Zr / ⁹⁰ Zr比率可由三阶段Nb-Zr演化解释。中观菱铁矿的母体。由于初始太阳系⁹² Nb / ⁹³ Nb的精度提高了6倍，我们可以证明存在⁹²早期太阳系中的Nb提供了进一步的证据，表明Ia型超新星和核塌陷超新星都对光p核产生了贡献。