中国南方丘陵区不同母岩型红土成土特征研究——以赣南地区为例

Research on Formation Characteristics of Different Parent Rock Pattern Red Clay in Hilly Area of Southern China——Take Gannan Region as Example

综合运用化学成分分析、磁化率分析等技术手段,对黄金(HJ)剖面、沙河(SH)剖面和田村(TC)剖面间隔20cm取样分析,研究发现,田村红土剖面常量元素Si、K、Ca、Mg和Na在整个剖面基本上表现为淋溶迁移的特征,由下部往上部表现出迁移程度有逐渐增强的趋势;微量元素V、Cr和Mn累积率多数样品位于0.2～0.5之间,属于中度累积,并且由下往上呈现逐渐增强的趋势。这些都说明了赣南地区红土在当前气候条件下仍进行着明显的脱硅和富铝化作用。此外,三个剖面不同红土层低频质量磁化率大小关系为:红壤层<均质红土层<网纹红土层,第四纪红土低频质量磁化率平均值低于花岗岩红土。接近地表的样品同时出现了低频质量磁化率值反而较低,可能与赣南地区长期高温多雨的气候环境有关。三个剖面硅铝系数值、铝铁系数值由底部往上总体上呈现逐渐递减的趋势,而铝铁硅系数曲线值由底部往上总体上是递增的趋势,(<1μm)的粘粒百分含量曲线也有这样的变化趋势,反映了三个剖面风化程度由下往上逐渐增强,三个剖面曲线变化曲线锯齿状波动,说明风化程度也不是完全按照由底部往上正向递增的变化。

The chemical compositions and magnetic susceptibility were tested and analyzed in Huangjin （HJ） section, Shahe（SH） section and Dangtang（DT） section, and found that the major element （Si,K,Ca,Mg,Na） showed the＇characteristic of leaching and movement in Tiancun section,and increasing tendency from the bottom upwards,The accumulation of trace element （V,Cr, Mn） located between 0.2 - 0.5, and belong to moderate accumulation, and increasing tendency from the bottom upwards. All this points to the same conclusion：The desilica-allitization of red clay is in the pipeline on modern climate environment. The low frequency magnetic susceptibility of red clay zone. The vermiculated red clay is better than red soil horizon is better than soil ho- rizon in magnetic susceptibility,The average magnetic susceptibility of the quaternary red clay is less than that of granite red, the magnetic susceptibility surface goil get lower than underneath red clay. This may have some connection with warm and wet climate environment in gannan region. The coefficient of SiO2/Al2 O3 and Al2O3/Fe2 O3 has an decreasing tendency from the bottom upwards,while coefficient of R2 O3/SiO2 increasing tendency from the bottom upwards. Reflecting the degree of weathering get stronger and stronger from the bottom upwards.