关键词: 陆架沙漠化, 沙漠, 风成沙, 风棱石, 海面变化

Abstract: Since 1991, some scholars have proposed the hypothesis that at the end of the late Pleistocene when the sea level was low and glaciation reached its maximum, the environment of China’s continental shelf was once a desert. The idea has been used to interpret the formation of the remnant deposits in the shelf region. The main evidence includes the presence of uniform disintegration of marine strata, extensive mixed deposits, long erosional basal plane, repose angle type of structure, buried dune groups and ventifacts. We contend that whereas the idea has some merit when the environment at that time is seen at the macro scale, the evidence submitted thus far is not convincing. Moreover, the idea does not take into consideration the possible impact of aeolian sand on the environment during marine transgression in the post glacial period. On this issue, we offer three views. (1) In the absence of biological evidence, to distinguish aeolian sand facies (ancient sand dunes) from the desert environment (ancient desert) should follow the principle of using multiple indices, and the indices selected should be able to diagnose landform processes and environmental features. But thus far much of the evidence proposed to support the hypothesis such as the “buried sand dune groups” is not unique to desert environment. (2) Although ventifacts (aeolian gravel) do indicate strong aeolian activities, they are not the only indicator of an arid desert environment. A comparative analysis of the grave forms and surface texture of the gravel from the seabed of the South Sea with the ventifacts of a modern desert environment shows that they differ markedly. They should not be regarded as the same thing. (3) Under the dry and cold glacial climate, aeolian sand (sand dunes) does not speedily cemment and diagenize into rocks. In addition, aeolian san (sand dunes) was highly susceptible to damage and change by marine trnasgression during the post glacial period. Thus it is not likely that sediment structure such as repose angle type of structure and sand dune morphology such as buried sand groups could be preserved in large areas. In short, the remnant deposits on China’s continental shelf should not be seen as ancient desert deposits.

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