Benthic Foraminifera as Paleoenvironmental Indicators and Their Paleooceanographic Significance around the Cenomanian-Turonian Boundary in
详细信息
- 责任者：Jia Jianzhong (School of the Earth Science and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Wan Xiaoqiao
- 刊名：Acta Micropalaeontologica Sinica
- 出版年：2010
- 卷期：27(2)
- 关键词：有孔虫类 ; foraminiferas ; 西藏 ; Tibet
- 页码：p.135-143
- 图表：4 illus., 2 tables, 43 refs.
- 分类号：1103
- issnNo：ISSN1000-0674
- isbnNo：CN32-1189/Q
摘要
The benthic foraminifera across the C/T boundary can be divided into three evolution stages, and both the main advantage species (Dorothia, Anomalinoides, Lenticulina, Conobina etc.) and plankton/benthos ratios [P/(P+B)are of 50%～80%] indicate that the habitat type is Ⅳ2 (outer shelf-shelf edge environment) with the water depth approximately 100～200 m. The benthic foraminiferal oxygen index（BFOI）ranges from-6 to-25, corresponding to the dissolved oxygen content of about 0.7～1.4 ml/L which belongs to suboxic condition. The benthic foraminiferal microhabitat（deep infauna/epifauna）shows a higher primary productivity in this area. Under the suboxic condition, a short-term blooming of primary producers may exacerbate the decrease of water oxygenation to form a more favorable conditions for organic matter accumulation and preservation, while the long-term conditions of a weak oxidation is likely to be caused by a series of environmental events around the C/T boundary.
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