UNDERWATER LOESS AND PALEOCLIMATE
泥河湾盆地的水下黄土堆积及其古气候意义

In East Asia during the Pleistocene there happened many loess shower events', in which a lot of loess ash fell into the ancient lake, then formed a special sediment in the lacustrine profile, this sediment is' called underwater loess. This paper deals with some characteristics of underwater loess in the Nihewan basin. On the basis' of pollen analysis and surface structure of quartzite sands, we conclude that the underwater loess was fromed in the dry-colder climate, and the lacustrine formed in the warm-dampness more than loess deposition region. Alternation of underwater-loess and lacustrine in the Nihewan series formed an underwater loess-lacustrine system, that provided climatic vari ations in Quaternary period: for example, since 72 0 000yrs. BP. paleoclimatic veriations can be obviously divided into 8 dry-cold and 8 warm-damp periods. It can be completely compared with variation of 18 content of deep-sea core V28 .23 and paleoclimatic evolution shown by loess-paleosoil system in lochuan.