Concentrations and spatial distribution of trace elements in secondary minerals provide valuable information about mobility controlling processes in natural fractures. Important examples include rare-earth element contents that act as analogues for the retention of trivalent actinides such as Am/Cm or Pu(III). The secondary phases (carbonates) investigated in this study originate from exploration drilling bore cores of the Swedish Nuclear Fuel and Waste Management Company SKB (Forsmark, Simpevarp and Laxemar, Sweden).

Here, high-resolution element analysis (Micro-X-ray Fluorescence-Spectrometry (µXRF) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS)) is applied to scan for Na and the trace elements Mn, Fe, Sr, Pb, Th and U as well as the rare-earth elements Y, La, Ce and Yb associated with carbonate fracture fillings. High resolution element maps highlight growth zones and microstructures within the samples, which are not detected by the usual point and line measurements. Evidence of phase-dependent partitioning is observed.

The partition coefficients, D, determined from formation water and carbonate data were compared to experimentally generated coefficients and values derived from a 17-year precipitation experiment carried out at the Äspö Hard Rock Laboratory (HRL).

Distribution coefficients of the light rare-earth elements La and Ce have been found to be relatively high in the studied samples, whereas the coefficients of distribution of Sr and U are remarkably low.

Overall, the results of this work show that the secondary calcite formed in deep granitic fractures coprecipitated periodically with significant amounts of radionuclide analogues (i.e., rare-earth elements).

次生矿物中微量元素的浓度和空间分布为天然裂缝中的流动性控制过程提供了有价值的信息。重要的例子包括稀土元素含量，它们作为类似物用于保留三价锕系元素，例如 Am/Cm 或 Pu(III)。本研究中研究的第二相（碳酸盐）来自瑞典核燃料和废物管理公司 SKB（Forsmark、Simpevarp 和 Laxemar，瑞典）的勘探钻孔岩心。

在这里，高分辨率元素分析（微 X 射线荧光光谱法 (µXRF) 和激光烧蚀电感耦合等离子体质谱法 (LA-ICP-MS)）用于扫描 Na 和微量元素 Mn、Fe 、Sr、Pb、Th 和 U 以及与碳酸盐裂缝充填物伴生的稀土元素 Y、La、Ce 和 Yb。高分辨率元素图突出了样品中的生长区域和微结构，这些是通常的点和线测量所无法检测到的。观察到相位相关分区的证据。

将根据地层水和碳酸盐数据确定的分配系数D与在 Äspö 硬岩实验室 (HRL) 进行的 17 年降水实验得出的实验产生的系数和值进行比较。

研究发现轻稀土元素 La 和 Ce 的分布系数在研究样品中相对较高，而 Sr 和 U 的分布系数非常低。

总体而言，这项工作的结果表明，在深花岗岩裂缝中形成的次生方解石与大量放射性核素类似物（即稀土元素）周期性地共沉淀。