Study on borehole provenance tracing and fluvial sediment diffusion in the Bohai Sea: Double constraints from detrital zircon U-Pb age and in-situ geochemical element of apatite grains

Abstract

Bohai Bay Basin, located in the North China Craton, are surrounded by the Yanshan Mountains to the north, the Taihang Mountains to the west, the Jiaodong and Liaodong peninsulas to the south and east, respectively. The Yellow River, combined with the Liaohe, Luanhe and Haihe rivers, produces a huge amount of detrital sediments to the Bohai Bay Basin each year. However, it has not been clear whether the sediments have been transported to the Bohai Sea and the gulf of Jiaodong Peninsula. In addition, there is no definite result suggesting that these sediments are related to the provenance in the gulf of Jiaodong Peninsula. Zircon and apatite are common accessory minerals in the river sediments. The zircon U-Pb age and the in-situ geochemical data of apatite grains show significant differences in different regions, making them the ideal minerals for the provenance study. In this case, we used the published detrital zircon U-Pb ages from the major inflow rivers of the Bohai Bay Basin, combining with the drilling cores zircon U-Pb ages and integrating with the multi-dimensional identification (MDS) of kolmogorov-smirnov statistical method, to systematically identify the potential source areas in the Liaodong Bay, Bohai Central Basin and Laizhou Bay. The results show that the detrital sediments in the Liaodong Bay mainly came from the Liaohe River, while that in the Bohai Central Basin and Laizhou Bay from the Yellow River. The Yellow River plays a major role in the material composition of the central and western parts of the Bohai Sea. At the same time, we carried out the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on the detrital apatite grains from the lower reaches of the Yellow River (n=70), and the Weihai Bay (n=120) and Yintan Bay (n=60) from the Jiaodong Peninsula. The results show that there is no provenance relationship between them. Combined with the in-situ geochemical analysis results of detrital K-feldspar in this area, it further indicates that there is no provenance relationship between the Yellow River and the gulf of Jiaodong Peninsula. Therefore, the combination of in-situ geochemical analysis of detrital zircon and apatite helps to accurately determine the provenance relationship.

Keywords

• bohai sea
• jiaodong peninsula
• zircon
• u-pb ages
• apatite
• provenance