北部湾北部上更新统的沉积特征及其记录的古环境

晚更新世100 ka以来作为重要气候阶段对后续环境演化影响深远。北部湾位于东亚低纬度季风区，为冷暖气团影响交汇带，是我国最靠近印度洋的大型海湾，沿海地势崎岖，山洪暴发，需要加强对该阶段气候波动及演化研究。在北部湾北部钦州湾口外近浅海钻取了海底岩芯，岩芯直达第四系地层下伏风化壳且进尺为80.05 m，文章对上更新统25.1~9.7 m岩芯段沉积物进行了粒度、微量元素、碎屑矿物、微体古生物测试鉴定以及¹⁴C与光释光测年。对数据的研究结果显示，该岩芯段孢粉为热带-亚热带山地植被，所处沉积环境为河流相，沉积要素波动变化并具有阶段性特征，物源来自周边陆区风化侵蚀。划分出4个岩芯深度段及相应的4个气候阶段，并对测年数据应用线性插值方法得到气候阶段为：末次间冰期（103~60 ka）水动力低能-高能环境、末次冰期早冰阶（60~46 ka）低能环境、末次冰期间冰阶（46~19 ka）低能-高能环境、末次冰期晚冰阶（19~11.4 ka）低能环境，均与相邻云贵高原和中国长江以南地区同期区域气候具有可比性。除此之外，还辨识出67 ka前后出现了一次暖事件，具有颗粒变细，有机质、微量元素、黄铁矿和褐铁矿等含量出现异常峰值并且相对增幅极高的特征，表明环境湿热和微生物还原活跃等。该暖事件在时间上与Dansgaard-Oeschger旋回（D-O旋回）序号19暖事件最为接近，序号18暖事件则次之，说明在我国季风区的湖北三宝洞、重庆新崖洞、南京葫芦洞石笋研究已发现的对应D-O旋回暖事件序号20~18时期，再往西南沿岸同样发生了与D-O旋回可对应的暖事件。

The sedimentary characteristics of Upper Pleistocene and its palaeo-environmental records in northern Beibu Gulf

Under the tropical and sub-tropical climatic background, northern Beibu Gulf is an interaction zone between cold and warm air masses and is the gulf closest to Indian Ocean in China resulting frequent climatic fluctuations. By comparison with neighboring areas especially northern areas' rich data and research results, the study on palaeo-climatic fluctuations since Late Pleistocene in northern Beibu Gulf and their characteristics have almost not carried out yet. The seismic profile interpretation and geological core sediments analysis have revealed that there were buried river channels during Quaternary under seafloor outside Qinzhou Bay Mouth, which formed during sea transgression in Holocene and had become the transition zone from submarine slope to submarine plain. There are main run offs now Fangcheng River, Maoling River, Qin River, Dafeng River and Nanliu River from west to east along coastline of Qinzhou Bay and its neighboring areas.