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两种不同时代、相互接触的花岗岩,由于其化学成分上的差异以及后期水—岩反应,在漫长的地质历史时期内必然导致其中元素、天然放射性核素的迁移,这种迁移行为可类比为高放废物深地质处置库中放射性废物的近场迁移行为。广西资源县境内的某处印支期花岗岩(全岩Rb-Sr年龄214±3 Ma)和海西期花岗岩(锆石U-Pb年龄196±31 Ma)接触带,根据全岩化学成分、O、Pb同位素待征和铀系核素的~(234)U/~(238)U,~(234)U/~(230)Th,~(230)Th/~(238)U,~(226)Ra/~(230)Th等核素活度比值,其两侧花岗岩在其演化过程中成为一个相对开放的比学体系,但由于其附近没有明显的开放性断裂,其中常量元素、微量元素及天然铀系核素在接触带中的迁移距离仅约1～2m,接触面薄弱带中发生的水-岩反应仅使化学组分迁移约30 cm。花岗岩裂隙是流
Due to the difference in chemical composition and the later water-rock reaction, the granites that are in contact with each other in two different ages inevitably lead to the migration of elements and natural radionuclides during the long geologic history period. The migration behavior can be analogized as Near-field migration of radioactive waste in HLW deep geological repository. Indosinian granites (whole rock Rb-Sr ages 214 ± 3 Ma) and Hercynian granites (zircon U-Pb ages 196 ± 31 Ma) are located in the contact area of Indosinian in Guangxi Province. According to the chemical composition of the whole rock, O ~ (238) U, ~ (234) U / ~ (230) Th, ~ (230) Th / ~ (238) U, ~ 226 ) Ra / ~ (230) Th. The granites on both sides become a relatively open ratio system during their evolution. However, due to the absence of obvious open fractures in the vicinity, the contents of major and minor elements And the migration distance of natural uranium nuclide in the contact zone is only about 1 ~ 2m. The water-rock reaction in the weak zone of the interface only makes the chemical components migrate by about 30 cm. Granite cracks are flow