关键词: 中国西北, 全新世, 环境变迁

Abstract: The process of climatic and environmental changes is exposed based on the analysis of Holocene loess, Paleosol, colian sand , periglacial deposits, glacial deposits, saline-lake deposits, migration of cultural sites in the plateaus and basins of Northwest China. It is revealed that there are six climatic stages, comprising three climatic cycles from cold-arid to warm-humid in Holocene, each cycle is about 3600 or 3700 years.
Q¹₄, 10, 500－8500aB. P., the cold-arid stage of the first climatic cycle, colian loess deposited in the Loess Plateau, Periglacial deposits in the Inner Mongolia Plateau, saline deposits in the Qaidam Basin, the glacieres began retreating in Mt. Tianshan.
Q²₄, 8500-6800 a B. P. , the wam-humid stage of the first climatic cycle, a wide weath-ering-soilization period, Burozem, Brown Soil, Black loessial Soil formed on ground, lakc deposits and bog-Coal in lowland.
Q³₄, 6800-5000aB. P. , the cold-arid stage of the second climatic cycle. eolian loess deposited in the Loess Plateau, periglacial deposits, eolian sand in the Inner Mongolinan Pla－ teau, saline deposits in the Qaidam Basin, the glacieres progressed in Mt. Tianshan and other mountains in Western China because of the lowering of snow-line.
Q⁴₄, 5000－3120 aB. P., the warm-humid stage of the second climatic cycle. Another wearthering－Soilization period. soils, lake deposits, bog-coal formed. The drift was weath-ered chemically in Mt. Tianshan and soil even appeared on the sand dune of the Tarim Basin.
Q⁵₄, 3120-1400aB. P. , the cold－arid stage of the third climatic cycle. Another depositing period of eolian sand and loess, saline deposits. The glacieres progressed in Mt. Tianshan and other mountains of the Qienhai area.
Q⁶₄, last 1400 years, the warm-humid stage of the third climatic cycle. Modern soils form widely in the loess plateau and Inner Mongolia Pateau. The snow－line riscs and the glacieres retreat in the mountains of Western China, but the drifting sand keep moving ii the inland basins.