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利用多磁性参数(包括质量磁化率、频率磁化率、饱和等温剩磁、退磁系数以及热磁曲线)及磁组构分析,以长江中游武汉天兴洲近代河流沉积物为研究对象,探讨了近100年以来沉积物磁性参数变化特征及其对长江中上游水文变化及气候环境的指示.结果表明,上部组合带(0.60~1.50 m)和下部组合带(2.40~3.30 m)沉积物的磁性载体以亚铁磁性矿物磁铁矿为主,同时存在少量较稳定的不完整反铁磁性物质,中部(1.50~2.40 m)亚铁磁性矿物相对较少,且剖面上部沉积物的超顺磁(SP)颗粒对沉积物χ贡献较大.整个沉积剖面自下而上磁性矿物含量呈“C”字型变化,反映了“软”-“硬”-“软”的磁性特性.沉积物磁组构组合带研究显示,历史时期沉积环境水动力强度、颗粒排列有序化程度以及长江流速发生了明显的变化,沉积环境水动力强度经历了“不稳定”-“稳定”-“不稳定”的变化过程,反映了长江古水文状况的变化.近代沉积物磁性特征变化格局与1900年以来以来长江中上游“暖湿”-“温凉”-“暖湿”气候环境变化和“强降水”-“弱降水”-“强降水”以及长江汉口站流量变化过程相吻合.这一研究成果为深刻认识历史时期长江流域气候环境变迁其及对长江古水文和沉积环境的影响提供了重要的参考资料.
Taking the multi-magnetic parameters (including mass magnetic susceptibility, frequency magnetic susceptibility, saturation isothermal remanent magnetization, demagnetization coefficient and thermal magnetic curve) and magnetic structure analysis, taking the modern river sediments of Tianxingzhou in Wuhan in the middle reaches of the Yangtze River as the research object, The characteristics of sediment magnetic parameters and its indication to the hydrological changes and climate in the middle and upper reaches of the Yangtze River since 100 years.The results show that the magnetic carriers of the sediments in the upper combination zone (0.60-1.50 m) and the lower zone (2.40-3.30 m) The ferrimagnetic mineral magnetite is mainly composed of a small amount of relatively stable and incomplete antiferromagnetic materials, while the ferrite magnetic minerals in the middle (1.50-2.40 m) are relatively few and the superparamagnetic (SP ) Particles contribute more to the sediment χ, and the magnetic mineral content of the whole sedimentary section shows a “C” -shaped change from bottom to top, reflecting “soft” - “hard” - “soft” Magnetic properties: The study of the magnetic fabric combination of sediments shows that the hydrodynamic strength, the order of particle arrangement and the velocity of the Yangtze River have changed obviously during the historical period. The hydrodynamic strength of the sedimentary environment underwent “unstable” “Stable ” - “unstable ” change process, reflected The change of paleo-hydrology in the Yangtze River: The change of magnetic characteristics of the modern sediments since 1900 has been related to the change of climate and climate in the middle and upper reaches of the Yangtze River since “warm and wet” - “warm and cool” - “warm and wet” “” - “Precipitation ” - “Strong Precipitation ” and the change process of the Changjiang River Hankou Station.The result of this research is to deeply understand the change of climatic and environmental conditions in the Yangtze River Basin during the historical period and its impact on the ancient hydrology and sedimentary environment of the Yangtze River Impact provides an important reference.