Establishing the nickel (Ni) isotopic composition of the upper continental crust (UCC) is crucial for using the Ni isotope system to trace biogeochemical processes and understand crust-mantle interactions. This study reports the Ni isotopic composition of eighty-four well-characterized upper crustal samples, including granites, granodiorites, tonalite-trondhjemite-granodiorite (TTG), loess, river sediments and glacial diamictites, to constrain the Ni isotopic composition of the UCC. Significant variations in δ⁶⁰Ni are revealed for I-type (0.02‰ – 0.26‰), A-type (-0.05‰ – 0.08‰) and S-type (0.08‰ – 0.36‰) granites for the first time. These Ni isotopic variations are attributed to magmatic differentiation for I- and A- type granites and source heterogeneity of S-type granites. The δ⁶⁰Ni values of fine-grained clastic sediments (including loess, river sediments and glacial diamictites) range from -0.01‰ to 0.23‰. Such δ⁶⁰Ni variations cannot be explained by Ni isotopic fractionation during chemical weathering because there are no clear correlations between δ⁶⁰Ni and Ni/Al₂O₃, or the chemical index of alteration (CIA). Instead, the δ⁶⁰Ni variations in fine-grained clastic sediments are likely inherited from source rocks. The δ⁶⁰Ni values of our samples for 3.2-3.5 Ga TTGs (0.00‰-0.13‰), 2.4-2.5Ga TTGs (0.04‰-0.13‰) and < 0.4 Ga granites (excluding S-type granites) are statistically indistinguishable (P<0.05, student's t-test), implying limited variation of δ⁶⁰Ni in the felsic igneous UCC since 3.5 Ga. Similarly, the δ⁶⁰Ni values of glacial diamictites suggest insignificant temporal variation in the weathered UCC since 2.4Ga. The data gathered in this study combined with literature data yields an arithmetic mean δ⁶⁰Ni value of 0.12 ±0.15‰ (2SD) for the UCC (ranging from -0.07‰ to 0.36‰). And the weighted average δ⁶⁰Ni is estimated to be 0.07±0.10‰ (2SD) or 0.11±0.09‰ (2SD) depending on the assumed δ⁶⁰Ni of the metamorphic rocks. Thus, a lithology-weighted average δ⁶⁰Ni needs to be further determined by future studies when the δ⁶⁰Ni values of metamorphosed sedimentary rocks in the UCC are constrained.

确定上大陆地壳 (UCC) 的镍 (Ni) 同位素组成对于使用镍同位素系统追踪生物地球化学过程和了解壳幔相互作用至关重要。本研究报告了 84 个特征明确的上地壳样品的 Ni 同位素组成，包括花岗岩、花岗闪长岩、英云长岩-长长花岗闪长岩 (TTG)、黄土、河流沉积物和冰川混杂岩，以限制 UCC 的 Ni 同位素组成。首次揭示I型（0.02‰～0.26‰）、A型（-0.05‰～0.08‰）和S型（0.08‰～0.36‰）花岗岩δ ⁶⁰ Ni显着变化。这些Ni同位素变化归因于I型和A型花岗岩的岩浆分异和S型花岗岩的来源非均质性。δ ⁶⁰细粒碎屑沉积物（包括黄土、河流沉积物和冰川混杂岩）的Ni值范围为-0.01‰～0.23‰。这种 δ ⁶⁰ Ni 变化不能用化学风化过程中的 Ni 同位素分馏来解释，因为 δ ⁶⁰ Ni 和 Ni/Al ₂ O ₃或化学蚀变指数 (CIA) 之间没有明确的相关性。相反，细粒碎屑沉积物中的δ ^{60 Ni 变化很可能继承自烃源岩。}3.2-3.5 Ga TTGs（0.00‰-0.13‰）、2.4-2.5Ga TTGs（0.04‰-0.13‰）和<0.4 Ga花岗岩（不包括S型花岗岩）的δ ⁶⁰ Ni值在统计上无法区分（ P<0.05，学生 t 检验），意味着 δ 的变化有限自 3.5 Ga 以来长英质火成 UCC 中的^{60 Ni。类似地，冰川混杂岩的 δ 60} Ni 值表明自 2.4 Ga 以来风化 UCC 的时间变化不显着。本研究收集的数据与文献数据相结合，得出 UCC 的算术平均值 δ ⁶⁰ Ni 值为 0.12 ±0.15‰ (2SD)（范围从 -0.07‰ 到 0.36‰）。并且根据变质岩的假定δ ⁶⁰ Ni，加权平均δ ⁶⁰ Ni 估计为0.07±0.10‰（2SD）或0.11±0.09‰（2SD） 。因此，当UCC变质沉积岩的δ ⁶⁰ Ni值受到约束时，需要通过未来的研究进一步确定岩性加权平均δ ^{60 Ni。}