Distribution of clay minerals in the soils of china
1983
JI-QUAN, X U
This paper gives an account of the clay mineral composition of several major soil types in China and discusses its relationship with the hydrothermal condition, topography, and parent materials. Various soils formed on analogous igneous rocks are conspicuously characterized by horizontal or vertical zonality in clay mineral composition. To a certain extent, the clay mineral composition of the soils developed on Pleistocene deposits differs from that of the soil developed on igneous rocks, and the soils derived from sedimentary rocks have more significant inheritance of soil minerals from their parent materials. Hydromica and chlorite are known as the common components in soils of less weathering, whereas smectite occurs in great abundance in chestnut soil, chernozem, podzolic soil, and clayey alluvial soils. The amount of vermiculite increases with the increase of leaching intensity until reaching its peak in mountain yellow earths, but in the upper horizons of strongly acid soils, cheluviation of aluminum always leads to the transformation of vermiculite into chlorite. Kaolinite and gibbsite are distributed extensively in subtropic and tropic soils; their content is closely related to temperature, rainfall, and parent materials. As a rule, soils derived from basic rocks tend to contain much more gibbsite and iron oxides. As a result of the uplift of earth crust, polygenetic mineralogical profiles may be regarded as the important characteristics of the soils on the Qinghai-Xizang Plateau.
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