Authigenic carbonates from cold seep systems, such as chimney and crust carbonate deposits, are important archives of biogeochemical processes associated with the migration and seepage of methane-rich fluids and seepages on the seafloor. Here we use a new U–Th dating method to precisely determine the ages of the authigenic carbonates of a chimney in the Okinawa Trough (OT), East China Sea. The method uses a series of heavy liquids (HL, a mixture of tribromomethane and alcohol with a density of 2.71–2.80 g/cm³) to separate subsamples of carbonate contaminated by detrital material. The contents of relevant elements (Al, Rb, Zr, Nb, and rare earth elements) of the subsamples reveal that the separation of the mineral phase was successful. Five samples from along the radius of a well-structured chimney (PES-1) from station D2-5 in the OT were analyzed and yielded U–Th ages of 28.8 ± 0.4 ka, 26.1 ± 0.5 ka, 24.4 ± 0.7 ka, 22.5 ± 0.6 ka and 20.1 ± 0.6 ka, from the exterior to the interior of the chimney section, and AMS ¹⁴C dating of the same samples produced the similar results. The agreement between the ²³⁰Th/U and AMS ¹⁴C ages suggests that the application of heavy liquid methods in U–Th dating can be very successful, and it reduces the influence of detrital contamination. Therefore, the approach has a great potential space for studying the evolutionary history of authigenic carbonates in cold seep systems. Moreover, the new ²³⁰Th/U ages show that the carbonate chimney was formed during the Last Glacial Maximum (LGM), which corresponding to the large sea-level fall in the East China Sea. Together with information on biogeochemical processes, the results will provide valuable geochronological information for the future study of active fluid venting on continental margins.

来自冷渗流系统的自生碳酸盐，如烟囱和地壳碳酸盐沉积物，是与富含甲烷的流体的迁移和渗流以及海底渗流相关的生物地球化学过程的重要档案。在这里，我们使用一种新的 U-Th 定年方法来精确确定东海冲绳海槽 (OT) 烟囱的自生碳酸盐年龄。该方法使用一系列重液体（HL，三溴甲烷和酒精的混合物，密度为 2.71–2.80 g/cm ³) 分离被碎屑材料污染的碳酸盐子样品。子样品中相关元素（Al、Rb、Zr、Nb 和稀土元素）的含量表明矿物相分离成功。对来自 OT 中 D2-5 站的结构良好的烟囱 (PES-1) 半径的五个样本进行了分析，得出的 U-Th 年龄分别为 28.8 ± 0.4 ka、26.1 ± 0.5 ka、24.4 ± 0.7 ka、22.5 ± 0.6 ka 和 20.1 ± 0.6 ka，从烟囱部分的外部到内部，相同样品的AMS ¹⁴ C 测年产生了相似的结果。²³⁰ Th/U 和 AMS ¹⁴之间的协议C年龄表明重液方法在U-Th定年中的应用非常成功，并且减少了碎屑污染的影响。因此，该方法对于研究冷渗系统中自生碳酸盐岩的演化历史具有很大的潜在空间。此外，新的²³⁰ Th/U年龄表明碳酸盐烟囱形成于末次盛冰期（LGM），与东海海平面大幅下降相对应。连同生物地球化学过程的信息，这些结果将为未来大陆边缘活动流体排放的研究提供有价值的地质年代学信息。