RECENT PROGRESS OF QUATERNARY RESEARCH OF CHINA AND GLOBAL CHANGES
近年来中国第四纪研究与全球变化

Extensive environmental changes took place during Quaternary. It is in this period that the regime of modern geomorphology of China was set up. With its vast territory covering the north temperate to the subtropical and the tropical zone,the country is diverse in geomorphological features, biotas, geological and tectonic backgrounds and Quaternary deposits. Almost all events of global environmental change can be found in the country.Quaternary sediments are useful materials to reconstruct the Quaternary environmental history. Among them, loess is in all senses the most important carrier of the environmental information in China. Characterized by its tremendous thickness and almost complete sequence, loess occupies an area of 450 000 km2, mainly concentrated in the Loess Plateau. Paleomagnetic dating revealed that the Gauss/Matuyama boundary is just near the bottom boundary of loess4]. It strongly support the suggestion of setting the bottom boundary of Quaternary at about 2.5 Ma B.P. Alternations of loess and paleosol reflect climatic changes.Thirty-seven alternations of loess and paleosol were recognized since 2.5Ma B.P.and indicate the same numbers of climate cycles. Each cycle start&; from a cold and dry episode to accumulate loess and ends with a warm and wet episode to produce paleosol2,3].Paleosol S0 now to Paleosol S26 at 1.8Ma B.P. in typical loess sections can clearly be found their correspondences after Stage 61 of the deep sea isotopic curve6]. In addition, a depth-age conversion curve obtained from the Weinan loess section7] is roughly correlatable to the SPECMAP curve8].The distribution of loess is closely related to that of desert. The loess-desert transition belt is fragile and sensitive to environmental changes. The expansion and reduction of desert are dependent upon environments.Lakes are other reservoirs of information of envilronmental changes.There are a great number of lakes in China: fresh water lakes are mainly distributed in East China and the Yunnan-Guizhou Plateau, while closed inland salt water lakes are distributed in Northwest China and the Qinghai-Xizang (Tibet) Plateau.The elevation of these salt water lakes varies from-155m to 4 900m. In the Qarhan salt lakes there are two thick salt beds: one brine salt bed formed at 25 000a B.P.and another potash salt bed formed at 15 000a B.P. These two salt beds represent two salt-forming episodes and hence two relatively .dry stages in Northwest China12].The fluctuation of the lake-water level is another indicator of climate change.Higher lake-water levels and the desalination of salt lake water usually correspond to moderate climate and higher precipitation.China is one of countries with well-developed karst in the world. There has been karst from Proterozoic to Quaternary and from subtropical South China to arid-semiarid North China15]. Both climate changes and tectonic subsidence and uplift influence the development of karst. Especially in Southwest China, a variety of kar