渤海海峡BHS01孔海陆交互相沉积物粒度特征及沉积环境分析

通过对渤海海峡BHS01孔上部40 m沉积物样品进行粒度测试分析，探讨渤海海峡地区的沉积环境变化。结果表明，渤海海峡BHS01孔上部沉积物平均粒径(X)介于3.2Φ~7.5Φ，以粉砂质砂、砂质粉砂为主；分选系数(δ)介于1.3~2.5，分选较差—差；偏度(Sk)为-0.4~3.0，以正偏、极正偏为主；峰度(Ku)1.9~12.4，表现为尖锐—正态。通过对沉积物粒级组成、粒度结构以及粒度参数随深度变化等特征进行分析，揭示了渤海海峡地区水动力条件较强，波动频繁的环境变化信息，据此将BHS01孔上部沉积物自下而上划分为7个沉积层段，反映渤海海峡地区中更新世以来经历了从浅海相-河流相-浅海相的沉积变化过程。

GRAIN-SIZE DISTRIBUTION PATTERNS OF THE CORE SEDIMENTS FROM BHS01 OF BOHAI STRAIT AND THEIR ENVIRONMENTAL IMPLICATIONS

Grain-size distribution patterns of the upper 40m of sediments of the core BHS01 are studied to detect the evolutional course of depositional environment of the Bohai Strait. Results show that the mean grain size of the sediments varies from 3.2Φ to 7.5Φ, indicating mixed sediments of silty sand and sandy silt. The sorting of the sediments ranges from 1.3 to 2.5, indicating poor sorting deposits. The skewness of the sediments are mostly dropped in the range of -0.4~3.0, showing a positive and super-positive skewness, while the kurtosis of the sediments varies from 1.9 to 12.4, showing an acute normal distribution. Based on the integrated analysis of grain size parameters, C-M diagrams, scatter diagrams and the changes in grain size with depth, it is concluded that the Bohai Strait was once a high-energy environment. Seven sedimentary units are recognized for the upper part of BHS01, which indicate the evolutional history of the region since Middle Pleistocene from shallow sea facies to fluvial facies, to shallow sea facies again.