The sequential extraction procedure is used to reconstruct the processes of redistribution of uranium isotopes in the mineral phases of the aquifer of the Vendian sandy-argillaceous deposits developed in the coastal territory of the European North of Russia. This aquifer has large resources of drinking and mineral groundwater which, however, are used in extremely limited quantities. This is due to the very complex nature of the hydrochemical conditions, and uranium-isotopic methods are used to clarify these conditions. The following mineral phases of core samples were characterized: adsorbed trace materials and carbonate minerals; ferrihydrate, amorphous minerals of Fe, Al and Si, and secondary U minerals; crystalline iron minerals; clay and some refractory minerals; and all remaining resistant minerals. The most resistant minerals, whose fraction ranges from 70.58 to 96.4%, have a minimum average uranium concentration of 0.47 ppm. This uranium is practically conserved in the rock, as a result of which the average ratio of its ²³⁴U:²³⁸U isotopes is close to equilibrium. In the remaining fractions, uranium is redistributed by groundwater along their flow lines from recharge areas in watersheds to areas of discharge into river valleys. Its maximum concentration (12.89 ppm) measurement is carried out by coprecipitation with iron hydroxides, then the uranium is adsorbed and precipitated with carbonates (9.14 ppm). The average ²³⁴U:²³⁸U is maximum in adsorbed trace materials and carbonate minerals (2.39 ± 0.36) and is close to that in fresh groundwater (2.8 ± 0.42). It is also increased in the amorphous minerals of Fe (1.53 ± 0.23). In general, there is a dependence of the ²³⁴U:²³⁸U activity ratio in rock on the degree of participation of groundwater in the deposition of hydrogenic uranium isotopes into the cracks and pores of these rocks. The results obtained contribute to the refinement of such a parameter as the retardation factor, which is necessary for understanding the processes of migration and concentration of uranium in sedimentary basins.

中文翻译：

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顺序萃取法在含沙矿床中铀同位素的分布

顺序萃取程序用于重建在俄罗斯北部欧洲沿海地区开发的Vendian砂质泥质沉积物含水层的矿物相中铀同位素的重新分布过程。该含水层拥有大量的饮用水和矿泉水资源，但使用量极为有限。这是由于水化学条件的性质非常复杂，因此使用铀同位素方法来阐明这些条件。对岩心样品的以下矿物相进行了表征：吸附的痕量物质和碳酸盐矿物；铁水合物，铁，铝和硅的无定形矿物以及次要的U矿物; 结晶铁矿物；粘土和一些难熔矿物；以及所有剩余的抗矿物质。最有抵抗力的矿物质 铀的最低平均浓度为0.47 ppm，其含量范围为70.58％至96.4％。这种铀实际上保存在岩石中，因此，其平均比率²³⁴ U：²³⁸ U同位素接近平衡。在其余的馏分中，铀沿着地下水的流线从集水区的补给区向排入河谷的区重新分配。其最大浓度（12.89 ppm）的测量是通过与氢氧化铁共沉淀进行的，然后铀被碳酸盐（9.14 ppm）吸附并沉淀。吸附的痕量物质和碳酸盐矿物中的平均值为²³⁴ U：²³⁸ U，最大值为（2.39±0.36），接近淡水的平均值（2.8±0.42）。铁的无定形矿物中含量也增加（1.53±0.23）。通常，存在²³⁴ U：²³⁸的依赖性岩石中的U活度比取决于地下水参与氢铀同位素向这些岩石的裂缝和孔隙中的沉积程度。获得的结果有助于改进诸如延迟因子之类的参数，这对于理解沉积盆地中铀的迁移和浓度过程是必不可少的。