【摘要】 发育于沉积物、砂岩和页岩残积物的藏北高山草原土、高山草甸土和亚高山草甸土,粘土矿物组成十分相似,各层次之间差异很少,都以云母和伊利石为主,伴有高岭、蛭石以及少量蒙脱和绿泥石,此外在高山土壤的表层则有非晶质水化氧化铁存在,似乎与土壤封冻期长有关。藏南高山土壤与亚高山土壤在粘土矿物组成上有显著不同,千枚岩发育的高山草甸土与藏北土壤接近,但同类母质所发育的亚高山草甸土,除表层可能受坡积物影响,以致云母和伊利石较多外,其余土层中伊利石含量都很低,以结晶较差的高岭为主,并伴有蛭石、三水铝矿和蒙脱,同时还有夹层矿物（12.6A）存在。三水铝矿聚集在剖面上部;而蒙脱则聚集在下部。山地灌丛草原土所处气候条件比较干旱,粘土矿物的主要组成是伊利石、高岭和蛭石,伴存蒙脱而没有三水铝矿,钙积层中蒙脱含量有所增多。喜马拉雅山南坡亚东附近森林植被下花崗岩坡积物所发育的山地灰化土各层都有伊利石、蛭石和高岭存在,此外,在A₂层有大量的蒙脱聚集,在腐殖质淀积层出现显著量的三水铝矿。同类母质所发育的山地棕壤中,粘土矿物组成以伊利石、高岭、三水铝矿、氧化铁矿物为主,蛭石和蒙脱数量甚少。西藏高原土壤中粘土矿物组成随着生物气候条件而发生相应的变化。藏北高山带和亚高山带以及藏南高山带气候干冷,土壤中粘土矿物的组成与母质中的相差不多,主要是脱钾和水化作用使云母变为伊利石。藏南亚高山带以下,气候比较温暖,所以,在比较湿润的亚高山草甸土中开始了脱硅作用,形成高岭和三水铝矿;在半干旱的山地灌丛草原土中则形成较多的蛭石。再向南,至湿润温暖的喜马拉雅山南坡山地棕壤中,则有大量的三水铝矿和较多的高岭形成。更多还原

【Abstract】 The constituents of clay minerals in 11 soil profiles of Tibetan highland were identified by chemical analysis, cation-exchange capacity determination, differential thermal analysis and X-ray diffraction. The mineral constituents in the clay fractions of alpine and subalpine soils of northern Tibet are very similar, illite being predominant, accompanied with kaolinite and vermiculite and sometimes small amounts of chlorite and montmorillonite. Besides, some amorphous free iron oxide is also present in the surface layer of alpine soils. There are significant differences in clay mineral constituents between the alpine and subalpine soils of southern Tibet. The clay fraction of alpine meadow soil derived from phyllite is similar to that of alpine soils in northern Tibet, but is quite different from that of subalpine soils derived from similar parent material, which contain greater amount of poorly crystallized kaolinite together with some vermiculite, gibbsite, montmorillonite and interstratified mineral （12.6 A）. Except in the surface layer, the content of illite in the profile of subalpine meadow soil of southern Tibet is very low. Gibbsite usually accumulates in the upper horizons, while montmorillonite often found in the lower horizons. In the mountain shrub-steppe soils, the clay minerals consist mainly of an association of illite, kaolinite and vermiculite accompanied with montmorillonite, which increases in the calcareous layers, but no gibbsite is found. In the mountain podzolic soil from granite origin, illite, kaolinite and vermiculite occur in all horizons. Besides, a great amounts of montmorillonite accumulate in A₂, and gibbsite appears in the humus accumulating layer. The clay minerals of mountain brown forest soil （also from granite origin） consist mainly of illite, kaolinite, gibbsite and iron oxides, the amount of vermiculite and montmorillonite is small. It is very clear that the clay mineral constituents of the soils of Tibetan highland vary under different bio-climatic conditions. Illite occurs abundantly in the cool dry alpine tract, much vermiculite in the semiarid mountain regions along the River Tsanpo; while kaolinite and gibbsite in large amount in the warm moist region of southern Tibet.更多还原