MAGNETIC SUSCEPTIBILTY VARIATIONS AND INFLUENCE FACTORS AT JINGYUAN LOESS SECTION, NORTHWESTERN CHINA

The environment magnetism investigation on a thick loess section at Jingyuan, Gansu, which is located in the northwestern margin of the Loess Plateau and close to the northern desert, indicates that there is no obvious difference in ferri-magnetic minerals assemblage between the major part of Chinese Loess Plateau and Jingyuan region of northwestern China. And the variation in magnetic susceptibilty at Jingyuan section could be correlated with the loess sequence and paleosol layers in Chinese Loess Plateau. But there are many unique characteristics of magnetic susceptibility in Jingyuan region rather than in the central part of Chinese Loess Plateau, such as the huge diffesence of magnetic susceptibility in the loess and paleosol. The value of magnetic susceptibility in paleosol S₅ is lower than paleosol S₄、S₃、S₂ and S₁. The magnetic susceptibility increases in an asceding order from the bottom to top. Data suggest that the total organic carbon (TOC) plays an important role in magnetic susceptibility variation in Jingyuan region.