干旱区生态环境知识资源中心

The origin and provenance of the loess deposits of the Chinese Loess Plateau (CLP) are still debated. In order to pinpoint the dust sources, surface samples from the piedmont of the Northeastern Tibetan Plateau, the Gobi Altai Mountains, and modern eolian dunes from the Tengger desert and Mu Us sand field were analyzed by using the detrital zircon dating technique. In order to quantitatively discriminate the content of different potential sources, zircon grains of different ages were grouped according to their tectonic origin. Zircon grains aged from 1300 to 550Ma were assigned to the Northeastern Tibetan Plateau, and grains aged from 550 to 0Ma to the Northeastern Tibetan Plateau or the Gobi Altai Mountains, or to a combination of the two. Zircon ages of around 2.8Ga to 1.3Ga may be a mixture of sources from the Northeastern Tibetan Plateau, Gobi Altai Mountains, or North China Craton. Sediments from the Tengger desert and Mu Us sand field consist of a mixture of the three sources and exhibit a high degree of spatial variability in terms of their source. In the northern part of the two deserts, 43-83% of the sediments are derived from the Gobi Altai Mountains, while in the south, material from the Northeastern Tibetan Plateau comprises 51-98% of the sediments. Loess deposits from the CLP also comprise a mixture of the three different sources, with material from the Northeastern Tibetan Plateau making the dominant contribution (65-100%), with material from the North China Craton and the Gobi Altai Mountains comprising 0-35% and 0-40% of the loess deposits, respectively. The contributions from the three sources to the loess deposits on CLP vary spatially. Application of the novel statistical method of provenance group analysis demonstrates that the loess deposits comprise a mixture of material from a broad region of northern China and that the Northeastern Tibetan Plateau material makes the dominant contribution.