Climate change recorded by the grain size end member since MIS 3 in Jingbian area

Abstract

As a typical multisource sediment, the grain size distribution of loess presents multi-peak distribution.End member analysis can be used to separate the end member components representing different sediment sources and sedimentary dynamics from the complex sediment size, which has been widely used in loess research.In this paper, Paterson parametric end member model was used to separate and explained the end member size of Sandaogou profile located in the southeastern margin of the Mu Us Desert.The analyzed results indicated that the Sandaogou loess in Jingbian was divided into four end members: EM1(8.93 μm) was the background dust; EM2(25.18 μm) was a component related to monsoon circulation.EM3(39.91 μm) and EM4(56.37 μm) were components related to winter wind.Among them, EM3 was the main component of loess in the loess plateau and EM4 was roughly the same grain size as modern sandstorms.Through the analysis of the curves of the end member components with age, the following conclusions were drawn: the profile recorded that the Jingbian area had experienced MIS 3(32.8-29.8 ka BP), LGM(29.8-22.8 ka BP), last deglacial(22.8-11.3 ka BP) and Holocene(8.7-1.7 ka BP) since MIS 3. Three climatic rapid change evented and cycles Dansgaard-Oeschger in deglaciation Heinrich 1(16.2-13.8 ka BP), Bølling-Allerød(13.8-12.8 ka BP) and Younger Dryas(12.8-11.3 ka BP) were recorded.The profile also recorded three major expansion-contraction cycles during last glacial period of the Mu Us Desert, and three dry sand events during the Holocene(8.7-8.2 ka, 6.0-5.0 ka, and 3.5-2.5 ka).

Keywords

• loess
• grain size
• end member component
• climate change
• desert expansion and contraction
• jingbian area