In this study, element geochemistry and zircon chronology are used to analyze the Oligocene sediments in the Baiyun Sag, Zhujiang River Mouth Basin. The experimental results are discussed with respect to weathering conditions, parent rock lithologies, and provenances. The chemical index of alteration and the chemical index of weathering values of mudstone samples from the lower Oligocene Enping Formation indicate that clastic particles in the study area underwent moderate weathering. Mudstone samples exhibit relatively enriched light rare earth elements and depleted heavy rare earth elements, “V”-shaped negative Eu anomalies, and negligible Ce anomalies. The rare earth element distribution curves are obviously right-inclined, with shapes and contents similar to those of post-Archean Australian shale and upper continental crust, indicating that the samples originated from acid rocks in the upper crust. The Hf-La/Th and La/Sc-Co/Th diagrams show this same origin for the sediments in the study area. For the samples from the upper Enping deltas, the overall age spectrum shows four major age peaks ca. 59–68 Ma, 98–136 Ma, 153–168 Ma and 239–260 Ma. For the Zhuhai Formation samples, the overall age spectrum shows three major age peaks ca. 149 Ma, 252 Ma and 380 Ma. The detrital zircon shapes and U-Pb ages reveal that during Oligocene sedimentation, the sediments on the northwestern margin of the Baiyun Sag were supplied jointly from two provenances: Precambrian-Paleozoic metamorphic rocks in the extrabasinal South China fold zone and Mesozoic volcanic rocks in the intrabasinal Panyu Low Uplift, and the former supply became stronger through time. Thus, the provenance of the Oligocene deltas experienced a transition from an early proximal intrabasinal source to a late distal extrabasinal source.

本研究利用元素地球化学和锆石年代学来分析珠江口盆地白云凹陷的渐新世沉积物。讨论了有关风化条件，母岩岩性和物源的实验结果。下渐新世恩平组泥岩样品的化学变化指数和风化值化学指数表明，研究区的碎屑颗粒经历了中度风化。泥岩样品表现出相对丰富的轻稀土元素和贫化的重稀土元素，“ V”形负Eu异常和可忽略的Ce异常。稀土元素的分布曲线显然是右倾的，其形状和含量类似于后阿尔奇时代的澳大利亚页岩和上陆壳，表明样品起源于上地壳的酸性岩石。Hf-La / Th和La / Sc-Co / Th图显示了研究区域沉积物的相同起源。对于来自恩平河三角洲上游的样本，总体年龄谱显示了四个主要年龄峰。59-68 Ma，98-136 Ma，153-168 Ma和239-260 Ma。对于珠海组样品，总体年龄谱显示出三个主要年龄峰。149马，252​​马和380马。碎屑锆石的形状和U-Pb年龄表明，在渐新世沉积期间，白云凹陷西北缘的沉积物是由两个物源共同提供的：华南前褶皱带的前寒武纪-古生代变质岩和中生代的中生代火山岩。番Pan低层隆起，前者供应随着时间的推移变得更强。因此，