中国黄海南部的海底砾石是风成砾石吗?

Are These Stones from Seabed of the Southern Yellow Sea of China Ventifacts?

近年来 ,一些学者提出在末次盛冰期低海面时期中国大陆架以风力作用为主 ,并发展为干旱沙漠化环境的理论 ,其主要证据之一就是在南黄海海底发现了“风成砾石”。但南黄海海底砾石的扁平和长条形态 ,以及无定向线形风蚀沟槽分布的表面结构特征不具备风棱石的特点 ;海底砾石分布区与其北部“沙漠化区”以及海底黄土沉积区的位置关系和偏北风吹扬下沉积物粒度的区域分异规律不符。因此 ,南黄海海底砾石不宜定为“风成砾石”。另外 。

Since 1991,some researchers have proposed a hypothesis which claims that the continental shelves of China were once desert environment during the low sea\|level of the last glacial maxim in the late Pleistocene. One of the most important evidences of the shelf desertization is that many stones have been collected from the seabed of the southern Yellow Sea of China, which was regarded as ventifacts by the hypothesis.\;In this paper, the shape and surface characteristics of the seabed stones have been carefully analyzed, and the following differences have been found existing obviously between the seabed stones and ventifacts.\;First, the shapes of the stone are longish and flat. There are no facets on the surface, which are often regarded as fundamental characteristics of small ventifacts (<10 cm). Second, on the surface of the stones, there are no directional arranged flutes and grooves, which are resulted from the wind abrasion, and they often appear on the big ventifacts (>10 cm). Third, the location of the stones is to the south of the seabed relict and loess regions, which are opposite direction to the north wind. According to the hypothesis, the north wind were dominant during the low sea\|level of the last glacial maxim, thus the regional changes of grain size of the relict deposits on the shelves should become thinner and thinner from north to south. In a word, it is not suitable that the seabed stones from the southern Yellow Sea were regarded as ventifacts.\;Moreover, although ventifacts are indicative of intense wind activity, they do not necessarily signify, as they also form in temperate regions along ocean or lake margins, and in periglacial settings. Therefore, ventifacts cannot be taken as diagnosis of desert environment.