涌潮沉积揭示长江河口湾全新世最高海面

海面变化对沿海地区的自然环境和社会经济有着重要影响，了解过去海面变化规律可以为预测未来海面上升情景提供参考依据。以长江古河口湾湾顶附近的扬州市昌建广场建筑工地所揭示的自然沉积剖面（CJGC剖面）为研究对象，通过详细调研，在剖面下部发现了保存有海相贝壳的涌潮沉积，为研究全新世最高海面和最大海侵提供了绝佳的地质材料。通过系统的沉积相与光释光（OSL）年代学研究，重建了古河口湾中全新世以来沉积环境的变化过程。结果表明，该地点中全新世以来经历了从陆相→潮滩→河口沙坝→河漫滩的沉积环境变迁，清晰显示了由海侵到海退的变化过程。OSL测年数据表明长江河口全新世最高海面和河口湾湾顶最大海侵出现的年代约为5.6 ka，当时对应的海面高度不低于海拔1.3 m，这一时期的高海面在世界多地均有记录。

The sea-level highstand of the Changjiang River estuary in the Holocene revealed from tidal bore deposits

Sea level changes have an important impact on the natural environment and community economy of coastal areas. Understanding the evolution of sea level in the past could help predict the future sea level rising. In this study, a natural Holocene soil outcrop (CJGC profile) was scrutinized. The profile was located in a construction site of Changjian Square in Yangzhou City, east Jiangsu Province in ancient estuary of the Yangtze River. The tidal bore deposits contain euryhaline mollusc shells in the lower part of the profile, which provides excellent geological materials for studying the sea-level highstand and the maximum transgression in the Holocene. In addition, we studied the sedimentary facies and conducted optically stimulated luminescence (OSL) dating, from which the evolution of sedimentary environment in the study area since the middle Holocene was reconstructed. Results show that this site has undergone sedimentary environmental changes of land →tidal beach→river mouth bar→floodplain, which clearly shows a change from transgression to regression. The OSL ages show that the sea-level highstand and the maximum transgression of ancient Changjiang River estuary in the Holocene appeared at ~5.6 ka in elevation no less than 1.3 m above sea level, which is consistent with the sea-level highstand of the same period found elsewhere in many places of the world.