地理学报 ›› 1996, Vol. 51 ›› Issue (3): 251-259.doi: 10.11821/xb199603007

• 论文 • 上一篇    下一篇

阿拉斯加巴罗地区AB-67钻孔的微体动物群及其古环境意义

李元芳, 张青松   

  1. 中国科学院, 国家计划委员会地理研究所,北京100101
  • 收稿日期:1995-08-01 修回日期:1995-11-01 出版日期:1996-05-15 发布日期:1996-05-15
  • 基金资助:
    国家自然科学基金,中国科学院中美合作特别资助

MICRO FAUNA IN BOREHOLE AB-67 AND ITS PALAEO ENVIRONMENTAL SIGNIFICANCE IN BARROW,ALASKAN ARCTIC

Li Yuanfang, Zhang Qingsong   

  1. Institute of Geography,Chinese Academy of Sciences and the State Planning commission of P.R. China, Beijing 100101
  • Received:1995-08-01 Revised:1995-11-01 Online:1996-05-15 Published:1996-05-15

摘要: 根据对AB-67钻孔岩芯中微体动物群的分析,本文讨论了北极阿拉斯加巴罗地区过去450年的气候环境变迁历史。

关键词: 阿拉斯加, 微体动物群, 环境演变;

Abstract: A60cm depth core of about 450 years old was drilled from Elson Lagoon in Barrow, Alaskan Arctic(70°21’N, 156°40’W)in the August,1994.The drilling site was located in a water Of 2m deep and was 1.5km away from coast.About 50 samples with intervals of 1-2cm were taken from the core to analyze the micro-fauna.Based upon the distribution properties,8 genera and 13 species of foraminifera were identified and three assemblages were distinguished:(1) At the lower part(35-60cm) of the borehole AB-67 Assemblage Elphidium orbiculareElphidium clavatum were distributed,in which the in which the dominant species were Elphidium orbiculare,E.clavatum, E.bartletti,Buccella frigida,et al.,without gluey shell foraminifera;(2) Assemblage buccella frigida-Ammotium cassis were found in the middle part(19-35cm)of the core;(3) Assemblage Elphidium asklundi-Elphidium excavatum alba were in the upper part(0-19cm)of the core. 9 general and 9 species of ostracoda were identified too,which can be divided into two assem blages:(1) Assemblage Limnocythere sp.-Normanicythere leioderma which were distributed In the lower section(31-60cm)of the core and were characterized by existence of both maritime and ter restrial ostracoda;(2) Assemblage Cytheromorpha macchesneyi were distributed in the upper section(0-31cm)of the core.Based upon the assembled characters and ecological features of the microfauna in the borehole AB-67,environmental changes in Barrow,Alaska in the past 450 years can be recognized as follows:(1)Before 1740 AD(e.g.from the mid of the 16th century to the 18th century),It was rela tively cold and in a low sea level stage,which were concluded by the existence of both marine and non-marine micro-fauna.The non-marine ostracoda indicates a lake-stream deposition environment with fresh-brackish water.The marine micro-fauna was likely eurythermal and euryhaline forms,so the drilling site was estimated to be located at a river mouth or in a tidal zone near the coast and the sea level might be 2.5m lower than that of the present between the mid-16 century and mid-18 cen tury,which coincided with a little ice age.(2) From mid-18 century to mid-19 century,it was becoming warmer and a slight transgres sion commenced.(3)From mid-19 century to present,it as warming,accompanied by continuous transgression.

中图分类号: 

  • P532