ZHANG Junhui, LIU Bin, LI Dongxing, ZHOU Xionghui, KANG Xiuli, LIN Qing, JIANG Shan, WANG Yanhu

(1.College of geography and Environment, Baoji University of Arts and Sciences, Baoji Shaanxi 721013, China；
2.Shaanxi Key Laboratory of Disasters Monitoring and Mechanism Simulation, Baoji University of Arts and Sciences, Baoji Shaanxi 721013, China).

Abstract: Magnetic minerals in sediments are sensitive to changes in climate and environment. A comprehensive and systematic analysis of the magnetic characteristics of the WH1617 profile sediments in the Weihe River shows that the magnetic mineral content in the sediment is relatively low, the main magnetic minerals are magnetite and magnetic hematite, while containing hematite, the magnetic grain is mainly multi-domain (MD); χARM/ SIRM (the ratio of non-hysteresis residual magnetism magnetization to saturated isothermal residual magnetism) has a good positive correlation with rainfall, and further analysis shows that χARM/SIRM can be used as a proxy index to reveal the changes of precipitation in the Weihe River basin since 1957-2010, the 1957-1969, χARM/SIRM decrease of value indicates that the particle size of magnetic mineral becomes thicker and the rainfall decreases, and the 1969-1985, χARM/SIRM value increases, which indicates that the particle size of magnetic mineral is thinner, the rainfall increases, the 1985-1995, χARM/SIRM value decreases, the particle size of magnetic mineral becomes thicker, and the rainfall decreases relatively. The 1995-2010, χARM/SIRM value is incremented, the particle size of magnetic mineral becomes thicker, and the rainfall fluctuation increases, but the increase was modest. Through Morlet wavelet analysis, it is shown that the main periodic changes of 8a and 19a are present in the near modern rainfall of Weihe river basin, the main periodic changes of 8a and 16a are χARM/SIRM, and the periodic variation characteristics of the two are more consistent, which further indicates the effectiveness of χARM/SIRM as a substitute index of precipitation in Weihe sediments.

Key words: Weihe River; sediment; environmental magnetism; Rainfall

EARTH AND ENVIRONMENT Vol.47, No.3, Tot No.329, 2019, Page 235-246