珠江口盆地的沉积充填与珠江的形成演变

沉积物元素地球化学分析表明，南海北部地区沉积物渐新统与中新统明显不同，两者之间存在物源突变事件。这一沉积地质事件在时间上与南海扩张轴发生跳跃、滇西高原以及东喜马拉雅构造结的快速隆升等一系列地质构造事件十分吻合，是珠江以及珠江口盆地搬运—沉积—充填演化史上一次重大的转变。Ca/Si、CIA以及Al₂O₃等参数变化显示，珠江侵蚀区极有可能由渐新世近源硅酸盐为主的华南沿海地区拓展为中新世远达青藏高原东麓的云贵高原碳酸盐为主的地区，流域范围突然扩大。同时伴随沉积物供给增大，造成珠江口盆地从渐新世富砂为主的沉积堆积体系转变为中新世以来以泥为主的沉积堆积体系，显示出珠江的发育演化以及中新世以来的青藏高原隆升在南海北部的沉积充填演变中扮演了重要角色,对南海北部地区油气藏的形成影响深远。

Sedimentary Filling of the Pearl River Mouth Basin and Its Response to the Evolution of the Pearl River

The sediment geochemical composition between Oligocene and Miocene was different in the northern South China Sea,indicating a significant provenance change.This abrupt change coincided with a series of events including a seafloor spreading axis jump in the South China Sea and uplift of the Western Yunnan Plateau and Eastern Tibet Plateau,leading to obvious changes in drainage areas of the Pearl River and the sediment geochemical composition.The variations in Ca/Si,CIA and Al2O3 reflect that the erosion areas of the Pearl River transformed from close-to-source neighboring areas in the Oligocene to the Western Yunnan Plateau and Eastern Tibet Plateau since the early Miocene,and the provenance rock types changed from silicate to carbonate,as well as the main sediment composition changed from sand-dominated to mud-dominated material.Therefore,the evolution of the Pearl River and the uplift of the Tibet Plateau played a key role in the sedimentary transformation and accumulation in the Pearl River Mouth Basin.This abrupt change event has a profound influence on the evolution of petroleum offshore in the northern South China Sea.