Abstract: Tracing sediment sources in the Yellow River Basin is of great importance for understanding the coupling relationship between uplift and denudation of the Tibetan Plateau and marine sedimentation in the western Pacific margin. K-feldspar is one of the common rock-forming minerals in river sediments, and its Pb isotopic compositions are effective tools in the provenance tracing research of large rivers. However, this research has not been carried out in the Yellow River Basin. In situ Pb isotopes of 967 K-feldspar samples were obtained by laser erosion inductively coupled plasma mass spectrometer(LA-ICP-MS). The results of 206Pb/204Pb and 208Pb/204Pb ratios showed that the Pb isotopic compositions of K-feldspar grains in the Yellow River, Daxihe River and Huangshui River in Maduo-Tongde section were significantly different from those in Lanzhou section. The Pb isotopic composition of K-feldspar in Lanzhou section of the Yellow River is consistent with that in Bayannur section of the Yellow River, which are influenced by similar eolian provenance. K-feldspar grains from the Yellow River and Fen River in the Jinshan-Shaanxi Gorge are mainly from the Loess Plateau. The K-feldspar grains in the Weihe River mainly derive from the Qinling Mountains. The Pb isotopic compositions of K-feldspar grains in the Kaifeng and Lijin sections of the Yellow River are different to those in the upper reaches of the Yellow River and the North China Plate, but similar to those in the middle reaches of the Yellow River. The Loess Plateau plays a leading role in the source of K-feldspar gains in the middle and lower reaches of the Yellow River.

Key words: Yellow River, K-feldspar, isotope, Provenance

摘要： 示踪黄河流域的泥沙来源，对于认识和理解青藏高原隆升剥蚀和西太平洋边缘海沉积之间的耦合关系至关重要。钾长石是河流沉积物中常见的造岩矿物之一，其铅(Pb)同位素比值在大河物源示踪研究时效果良好，但这一研究在黄河流域还未开展。本文利用激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)对黄河流域15件样品进行分析，获得了967 颗钾长石原位 Pb 同位素结果。206Pb/204Pb 和 208Pb/204Pb 比值二维散点图和多维判别图(MDS)结果表明，玛多到同德段黄河、大夏河和湟水的钾长石Pb同位素组成与兰州段黄河存在明显差异；兰州段黄河钾长石Pb同位素组成与巴彦淖尔段黄河一致，二者受相似的风成物源区的影响；晋陕峡谷段黄河、汾河的钾长石主要来自黄土高原；渭河的钾长石主要来自秦岭。开封和利津段黄河的钾长石Pb同位素组成一致，都与黄河上游和华北板块明显不同，但与黄河中游相似。黄土高原对黄河中、下游的钾长石来源起主导作用。

关键词: 黄河, 钾长石, Pb同位素, 物源示踪