关键词: 黄河, 钾长石, Pb同位素, 物源示踪

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