AMS 14C测年揭示的渤海湾沿海低地第Ⅱ海相层年龄（Ⅱ）

摘要

在初步获得渤海湾海河南部沿海低地第Ⅱ海相层年龄大于43.5ka BP的基础上，在沧州北部和海河北部的沿海低地又利用6个新的机械钻孔岩心，建立了2条垂直于现代岸线的长剖面。根据沉积物岩性和有孔虫查明了第Ⅱ海侵层在剖面中的空间分布，并获得一组新的AMS 14C年龄数据。结果显示，在第Ⅱ海相层中新获得的9个AMS 14C年龄同样均大于43.5ka BP。至此，渤海湾3条垂直现代岸线剖面10个钻孔的第Ⅱ海相层的21个AMS 14C年龄均大于43.5ka BP，进一步证实了普遍发育于渤海湾沿海低地的第Ⅱ海相层形成于MIS 3阶段早期或MIS 5阶段，而不是前人认为的23~39ka BP。%Preliminary result has indicated that the age of the second marine layer in the southern coastal lowland of Bohai Bay is>43.5ka BP. Recently, six boreholes have been drilled in the coastal lowlands north of Cangzhou and north of the Haihe River, and two new profiles perpendicular to the modern shoreline were then established. Combined with the lithostratigraphy, foraminiferal as⁃semblages and AMS 14C dating results, the second marine layer in these cores has been identified spatio-temporarily. The dating re⁃sults of 9 samples collected from the second marine layer show that the ages are all older than 43.5ka BP. Up till now, 21 AMS 14C ag⁃es collected from the second marine layer in 10 boreholes, given by the authors, indicate that the widely distributed second marine layer was formed in the early MIS 3 or MIS 5 stages rather than 23~39ka BP as previously believed.