舟山群岛北部的地理环境与黄棕壤的形成——兼论新构造运动影响及红壤带的北界问题

舟山群岛北部历来划属红壤带,但良好发育且分布最广的是黄棕壤,因其多种性状与气候等环境酷似南京下蜀黄土上的典型黄棕壤。黄棕壤上无红化迹象,不能以下部有酸性古红土而将本区误定为红壤带。第四纪以来地球上有过多次气候波动,使红壤带的北界南北摆动。红壤带在目前不一定有红壤化作用在进行,它仅表示为红壤相对集中的地带。本文还讨论了该黄棕壤形成过程中,新构造运动在多方面的重要影响。

YELLOW BROWN EARTH ON THE ZHOUSHAN ISLANDS INTHE EAST CHINA SEA (WITH A DISCUSSION ON THEPROBLEM OF NORTHERN EDGE OF THERED EARTH ZONE)

: The northern part of Zhoushan Islands in the East China Sea is traditionally incorpora- ted with the red earth zone. But most of the widely spread and well developed zonal soil in this area should belong to the yellow brown earth. We have identified these soils by com- paring them with the typical yellow brown earths collected from Nanjing and Wuhan. Most of the soil properties are very much similar between them, such as clay minerals, CEC, SiO2/Al2O3 (clay), pH, color etc. Neotectonic movements with their accompanied soil-forming process in this area may be as follows: uplift leading to erosion-subsidence ltading to locss deposition-uplift and slight tilting northeast ward-relatively stable, yellow brown earth developed on loess de- posit-continuous uplift and soil degleization developed at the lower part of the soil profile. There is no indication of laterization in the profile of yellow brown earth. So we can say that no laterization developed since Q3. Although some acide red paleosol can often be found under the profile of yellow brown earth and may even expose on land surface when the erosion was severe we can not say this region belongs to the red earth zone. Since the end of Tertiary Period there have been many times of climatic fluctuations in the world. During the glacial age the laterization would be stagnated. The boundary bet- ween red earth and yellow brown earth will move north-ward and south-ward frequently. At present in the red earth zone we are not sure that laterization is going on or not. So the So- called "red earth zone" in Zhoushan Islands can be identified as relic red earth which occurred in some places in the Islands.