浙江省内不同成土母质红土粒度特征比较

浙江省内7个典型红土剖面红土粒度测试表明：（1）浙江省内红土发育母质多样，沉积环境和母岩性状对红土粒度特征的控制意义较为显著，粒度组成能够有效区分不同成因的红土类型．（2）金华汤溪（TX）、浦江上山西南（SSSW）、安吉（AJ）、金华湖海塘（HHT）剖面红土以粉砂粒组占优势，粘粒含量次之，但TX、SSSW、AJ剖面砂含量很小，均值0．13％～1．18％；HHT剖面125～2000μm之间粗粒组分明显．前者显示风成特性，后者受风动力以外其他近源动力改造．风成特性加积型红土的存在对于认识第四纪期间风尘沉积物在长江以南地区的分布和季风演化信息具有重要意义．（3）基岩风化壳型红土的粒度组成因母岩性质而不同．相比较，众数峰值以砂岩红土最粗（30—63μm），花岗岩红土次之（15—30μm），玄武岩红土最细（4—6μm）．此外，花岗岩红土在125～2000μm之间有明显的中粗砂组分；玄武岩红土在0．2—1．0μm之间有明显的粘粒组分；砂岩红土除众数粒度峰外，在2—4μm以及0．2—1．0μm之间还存在多个分量．玄武岩红土比砂岩和花岗岩红土更均化．

Comparative study of red earth grain-size from different parent materials in Zhejiang Province

Red earth grain-size of seven typical sections in Zhejiang Province was tested. The results show that ： （ 1） There were a variety of red earth parent materials in Zhejiang Province, sedimentary environment or rock characteristics influenced red earth grain-size feature notably. The grain-size feature not only contained the information of original sediment or rock, but also indicated the characteristics of pedogenesis, which could be used to distinguish different types of red earth effectively. （ 2 ） TX, SSSW, AJ and HHT sections had the highest content of silt 14 - 63 μm ）, the clay C 〈 4 μm ） come in second, but TX, SSSW and AJ sections have low content of sand（ 〉63μm） , the mean values were between 0.13% and 1.18% ; HHT section＇s coarse ingredient （ 125 -2 000 μm） was obvious, the former showed aeolian characteristics, the latter was altered by proximal power. Red earth with aeolian characteristics was significant in the recognizing of the distribution of the aeolian sediments in south of the Yangtze River during the Quaternary and the information of monsoon evo-lution. （3） Grain-size distributions of the weathering crust red earth depend on their parent materials and weathering characteristics. In contrast, mode peak was in 30 -63 μm from sandstone red earth, in 15 - 30 μm from granite red earth, in 4 - 6 μm from basalt red earth. Furthermore, granite red earth has obvious middling and coarse sand ingredient between 125 μm and 2 000 μm ; basalt red earth has obvious clay ingredient between 0.2 μm and μm ; Besides the mode peak, sandstone red earth still had other constituents at 2 - 4 μm, 0.2 - 1 μm. Basalt red earth was more even than sandstone and granite red earth.