江西九庐公路红土剖面的磁学特征及其反映的风化成土作用

Magnetic properties of red clay section along the Jiu-Lu highway at Jiujiang,Jiangxi and implications for pedogenesis

南方第四纪红土是研究古环境变化的重要载体.本文对采自江西九江的九庐公路红土剖面进行了详细的环境磁学研究,拟探讨多项磁参数在提取南方红土古环境信息方面的价值.结果显示,红土剖面上段的弱风化层,磁化率随着成土作用的增强而增大,反映了成土过程中产生的细颗粒亚铁磁性矿物导致的磁化率增加;而在剖面下段强风化的网纹红土层,表现为磁化率和退磁参数S比值下降但硬剩磁显著增加,反映强风化成土作用下不完整反铁磁性矿物的富集.与单一磁化率指标相比,多项磁学参数的综合运用可以在南方红土古气候重建领域发挥重要作用.

Quaternary red clay in southern China is an important media for the study of paleoenvironmental change. Detailed magnetic characterization was carried out on the JL（Jiu-Lu） red clay section at Jiujiang, Jiangxi Province, with the purpose to investigate the feasibility of magnetic properties in paleoclimate reconstruction. The results show that magnetic susceptibility increases with stronger degree of pedogenesis in the upper weakly weathering layer. However, magnetic susceptibility and S-ratio declines while Hard Isothermal Remanent Magnetization （HIRM） increases significantly in the lower strongly weathering reticulate red clay layer, which results from the enrichment of antiferromagnetic minerals. In comparison to magnetic susceptibility, an use of multiple magnetic parameters can play a significant role in paleoclimate reconstruction for red clay in southern China.