大亚湾全新世沉积与沉积环境变化

Changes of the Depositional Environment and Characteristics of Sedimentation during Holocene in Daya Bay

主要依据大亚湾中部海区B3802柱状沉积物的粒度、矿物、元素地球化学等特征,结合14C测年、有孔虫记录等对大亚湾海区全新世以来的沉积环境进行分析。结果表明,全新世以来大亚湾海区海平面波动上升,沉积速率逐渐下降,海水动力作用减弱。全新世初期为河口湾相沉积环境,广盐性有孔虫含量较高,海洋沉积物中陆源物质增加,气候由干冷转为温暖;全新世早―中期为正常海相环境,沉积物中海源物质增加,气候温暖湿润,指示当时海洋生态环境较好;全新世晚期为河海交互相沉积环境,海平面继续上升,气候仍然湿热。

According to the characteristics of the sediment particle size, mineral compositions and element geochemical, as well as the records of foraminifera and 14C age in B3802 core, the changes of depositional environment of the Daya Bay since Holocene are analyzed. The results indicate that： the sea level rose with fluctuations, sedimentary velocity dropped gradually since the early Holocene, the sea water dynamics was weaken. During the Holocene initial period, the depositional environmentwas associated with the euryhalinous foraminifera content, higher proportion of terrestrial sediment soureses, and a changing climate from biting cold to warm. The Holocene intermediate stage was associated with a normal marine environment, with increased oceanic sediments and a warmer and moist climate, indicating a good marine ecological environment. The latter Holocene period was associated with a transitional environment between river and the sea, as sea level continued to rise alternately andthe climate was still hot and damp.