Acta Geographica Sinica ›› 1998, Vol. 65 ›› Issue (s1): 76-82.doi: 10.11821/xb1998s1010

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  1. 1. The Institute of Archaeology Chinese Academy of Social Sciences, Beijing 100710;
    2. Department of Resources and Environmental Sciences, Beijing Normal University, Beijing 100875
  • Received:1997-01-10 Revised:1998-10-20 Online:1998-12-15 Published:1998-12-15
  • Supported by:

    Supported by National Natural Science Foundation of China

Abstract: The article studied the process of environmental evolution and characters of each stages for the past 600 years in Daihai District, through the clay minerals analysis, microelements analy-sis, organic matter content analysis, sporepollen analysis and ostracoda compound analysis of the sediment in the drills of central Daihai Lake and its historical data.Sediment in the 120 cm~80 cm part of drilling hole (600 a BP~400 a BP) contains high contents of organism and humid climate elements as Si, Al, Fe, Mn, and Ni, while the contents of ostracoda are low, with only less-salt-water limnocythere and fresh-water Candona existing in the middle of the this part of drill, reflecting a fresh-water environment of that period. The sporepollen contents are mainly Artemisia-, Chenopodiaceae, Pinus and Betula. Near the end of that period, the contents of Betula pollen increased a lot, and the average content of arbor sporepollen is over 27. 5%. Such data illustrate a temperate-cold and semihumid environmental of that period.Sediment in the 80 cm~40 cm part of drilling hole (400 a BP~200 a BP) contains more Os-tracoda than its former period does. Between 72 cm and 48 cm, a gram of sediment contains 1309~2383 Ostracodas, reflecting the more salty lake water. During this period, Illite and Boron contents are higher, while the warm-humid elements content become low. The content of Arbor sporepollen mainly Pinus and Betula, decreases a lot, while bush and grass sporepollen contents reach 75%~95%. The deeper part of this stage contains more Betula pollen, while the upper part contains more of Chenopodiaceae. These data represent a temperate-cold and semi-arid environmental character.The mumber of Ostracoda. mainly Limnocythere duhiosa and Leucocytherella trinoda, in-creases greatly in the sediment 40 cm to up (200 a BP~now). reflecting a more-salty-water en-vironment. Sporepollen are dominately bush and grass, with little content of Arbor, and the hu-mid climate elements decrease a lot, showing the temperate-cool and semi-arid environment and the developing tendency of arid climate.Form the division of sporepollen zone and environmental evolution periods . and also from the changing of environment data cycle. it can be concluded that there exists a quasi-cycle of cli-mate during the past 600 years’ evolution which changes every 200 years.

Key words: Daihai Central drilling, environmental evolution, sporepollen analysis, corresponding analysis

CLC Number: 

  • P531