文章通过碎屑锆石U-Pb测年和Hf同位素研究，揭示桂北地区丹洲期与南华冰期之间沉积转换的年代学记录。分别对丹洲群合桐组、拱洞组以及南华系长安组进行碎屑锆石U-Pb年龄和Hf同位素分析。结果表明，丹洲群合桐组和拱洞组具有相似的碎屑锆石年龄谱系，U-Pb年龄集中在720~1000 Ma、1700~2300 Ma和2400~2700 Ma。而南华系长安组的U-Pb年龄集中在650~720 Ma和720~1000 Ma，明显区别于丹洲群。丹洲群合桐组和拱洞组具有相似的Hf同位素特征，其ε_Hf(t)以负值为主，且多数锆石的二阶段Hf模式年龄（T_DM2）大于2400 Ma。而南华系长安组的Hf同位素特征区别于丹洲群，其ε_Hf(t)以正值为主，T_DM2值集中于1000~1300 Ma和1400~2200 Ma。碎屑锆石U-Pb年龄谱系和Hf同位素组成的不同，以及锆石形态和物源的差异，表明“雪峰不整合面”上下的南华冰期与丹洲期沉积地层之间存在明显的沉积转换。

U-Pb dating and Hf isotope analysis of detrital zircons from Hetong formation and Gongdong formation of Danzhou group and Chang’ an formation of Nanhuan system were carried out by LA-ICP-MS to reveal the chronological records of sedimentary transformation between Danzhou period and Nanhuan glacial period in northern Guangxi. The analytical results show that the Hetong formation and Gongdong formation of Danzhou group have similar detrital zircon age pedigrees, and the U-Pb ages are concentrated in 720-1000 Ma, 1700-2300 Ma and 2400-2700 Ma. The detrital zircon ages of Chang’ an formation of Nanhuan system are concentrated in 650-720 Ma and 720-1000 Ma, which are obviously different from Danzhou group. Hetong formation and Gongdong formation of Danzhou group have similar Hf isotopic characteristics, with negative εHf(t) and the TDM2 values of most zircons are greater than 2400 Ma. However, the zircon Hf isotopic characteristics of Chang’ an formation of Nanhua system are different from Danzhou group, with mainly positive εHf(t) values and TDM2 values concentrated in 1000-1300 Ma and 1400-2200 Ma. The differences of U-Pb age spectrum and Hf isotope of detrital zircon, combined with the difference of zircon CL image and provenance, show that there is obvious sedimentary transformation between Nanhua system and Danzhou sedimentary strata.