摘要
从１９９１年以来，一些学者把我国大陆架上的残留沉积作为古沙漠沉积，推测中国大陆架在末次冰期低海面时期以风力作用为主，并发展为干旱沙漠化环境。本文对我国塔克拉玛干沙漠沉积和南黄海大陆架残留沉积进行比较沉积学研究。结果表明，南黄海大陆架上的残留沉积不宜判定为古沙漠堆积。
Since 1991, some researchers put forward a hypothesis, in which it is inferred that it was once dominated by desert environment in the continental shelves in China during the low sea- level of the last glacial maximum in the late Pleistocene. This hypothesis has been used to interpret the origin and formation of the relict deposits in the shelf regions. The main evidences of the shelf desertification are disintegration of the integrated marine stratum, extensive mixed deposits, and erosional surface, texture of reposed angle, buried dunes, ventifacts, etc. In this paper, based upon the comparison of the sedimentary features between the desert deposits in the arid land (Taklamakan Desert) and relict deposits in the continental shelf (south Yellow Sea), it has been found that the following differances exist between the relict deposits and desert deposits. Firstly, the accumulated coastal land forms of the relict deposits, such as bars, deltas, shore terraces, etc., distribute extensively in south Yellow Sea, which were formed by wave process but not by wind process. Secondly, the dip angles of the relict deposit bedding, usually 10°- 23°, are far gentler than the reposed angle of dry eolian sand (33°－ 35°). Thirdly, the relict deposits are mainly consisted of silt. The silt content amounts highly to 20%, but there is no silt or only a little silt (usually < 5 % )in aeolian sand. Fourthly, the shape and surface texture of quartz sand of the relict deposits resulted from the process under aqueous environment without the surface features occurring on the grain surface of aeolian sand. Fifthly, the relict minerals are glauconites and the accessory-minerals of phosphorite, which positively formed under a shallow sea environment. Sixthly, there are a lot of Picea, Cupressaceae and Quercus pollen (total > 30% ) in pollen component of the relicts, which indicates a cold and wet paleoclimate. And there are many marine nonverte-bral animal fossils, such as foraminifera, ostracoda and molluscs in the relict deposits,
出处
《干旱区地理》
CSCD
北大核心
1999年第2期8-13,共6页
Arid Land Geography
基金
中国科学院新疆生态与地理研究所阜康荒漠绿洲生态系统观测试验站基金
关键词
残留沉积
沙漠环境
沙漠沉积
干旱区
沙漠
relict deposit
aeolian factes
desert environment
distinguish index
Taklamakan Desert
south Yellow Sea.
