Uncertainty for elemental and isotopic measurements in calcite by LA‐ICP‐MS is largely controlled by the homogeneity of the reference materials (RMs) used for calibration and validation. In order to produce calcite RMs with homogeneous elemental and isotopic compositions, we incorporated elements including U, Pb and rare earth elements into calcite through heat‐ and pressure‐induced crystallisation from amorphous calcium carbonate that was precipitated from element‐doped reagent solution. X‐ray absorption spectra showed that U was present as U(VI) in the synthesised calcite, probably with a different local structure from that of aqueous uranyl ions. The uptake rate of U by our calcite was higher in comparison with synthetic calcite of previous studies. Variations of element mass fractions in the calcite were better than 12% 2RSD, mostly within 7%. The ²⁰⁷Pb/²⁰⁶Pb ratio in the calcite showed < 1% variations, while the ²³⁸U/²⁰⁶Pb ratio showed 3–24% variations depending on element mass fractions. Using the synthetic calcite as primary RMs, we could date a natural calcite RM, WC‐1, with analytical uncertainty as low as < 3%. The method presented can be useful to produce calcite with controlled and homogeneous element mass fractions and is a promising alternative to natural calcite RMs for U‐Pb geochronology.

中文翻译：

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通过无定形碳酸钙的结晶将方解石中的U，Pb和稀土元素掺入：用于微量分析的参考材料的简单制备

通过LA‐ICP‐MS对方解石进行元素和同位素测量的不确定性在很大程度上取决于用于校准和验证的参考物质（RM）的均一性。为了生产具有均质元素和同位素组成的方解石RMs，我们通过热和压力诱导从无定形碳酸钙中析出的元素中掺入了包括U，Pb和稀土元素在内的方解石，这些元素是从掺杂元素的试剂溶液中沉淀出来的。X射线吸收光谱表明，在合成方解石中U以U（VI）的形式存在，其局部结构可能与含水铀酰离子的局部结构不同。与先前研究的合成方解石相比，我们的方解石对U的吸收率更高。方解石中元素质量分数的变化优于12％2RSD，大部分在7％之内。方解石中²⁰⁷ Pb / ²⁰⁶ Pb的变化率小于1％，而²³⁸ U / ²⁰⁶ Pb的变化率根据元素的质量分数变化3％至24％。使用合成方解石作为主要RM，我们可以确定天然方解石RMWC-1，分析不确定度低至<3％。提出的方法可用于生产元素质量分数受控且均质的方解石，并且是用于U-Pb地球年代学的天然方解石RM的有前途的替代方法。