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

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SEDIMENT ANALYSIS OF THE CENTRAL DRILLING SECTION IN DAIHAI LAKE AND ITS ENVIRONMENTAL EVOLUTION FOR THE PAST 600 YEARS

Wuyungerile1   

  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