ENVIRONMENTAL SIGNIFICANCE OF MAGNETIC SUSCEPTIBILITY AND GRAIN SIZE IN JINGERWA CORE, YANGYUAN BASIN

Based on the characteristic of grain size, the evolution of Yangyuan lake was divided into swamp, shallow lake, shallow-coastal lake and coastal lake, including eight high-low cycles, during the past 200ka. The 50~100μm grain size, >50μm grain size and median are the valid indicators of environmental change in coastal lake. The fine particle, <5μm and 2~50μm grain size, is good porxy in shallow lake. The values of magnetic susceptibility in Yanyuan lake are controlled by the amount of chemical deposit, grain size and sedimentary facies. They have positive correlation with the content of coarse particles in shallow-coastal lake, and with the content of fine particles in shallow lake. They have no clear correlation in coastal salt lake.