MINERALOGICAL STUDIES OF SEVERAL MAJOR SOIL TYPES DEVELOPED FROM GRANITE IN GUANGDONG

This study deals with the mineral composition of every class of red earth, latcritic fed earth and latosol developed from granite in Guangdong Province by analyses of chemistry, X-ray diffraction, differential therm and electron microscope. According to the results of analyses,minerals of feldspar group are directly formed into halloysite and kao-linite and then kaolimte is transformed into gibbsite .Minerals of mica group are formed intogoethjte, hematite, 14A mineral and sericite. Plagioclase may change into sericite, and further into hydromica by depotassiumation. In the light of different compositions of primary and secondary minerals in the soil,it is suggested that the composition characteristics of soil minerals be affected not only by factors of soil formation that are dominated by zonality and bioclimatfc conditions, but also by complex reflection of all other factors of soil formation. Moreover, the neotectonic movement may also be one of the affecting factors .The intensity of weathering to minerals of latosol developed from granite in Hainan Island is not the strongest one in comparison with lateritic red earth and red earth. Whether it belongs to latosol needs further discussion.