| 西藏南部晚白垩世大洋氧含量变化的生物特征 |
| |
| 引用本文： | 司家亮,高莲凤,万晓樵.西藏南部晚白垩世大洋氧含量变化的生物特征[J].地学前缘,2005,12(2):113-122. |
| |
| 作者姓名： | 司家亮 高莲凤 万晓樵 |
| |
| 作者单位： | 中国地质大学,地球科学与资源学院,北京100083;中国地质大学,地球科学与资源学院,北京100083;中国地质大学,地球科学与资源学院,北京100083 |
| |
| 摘 要： | 西藏南部是中国海相白垩系分布最好的地区,基于岗巴宗山和江孜床得两条经典剖面,识别出分别对应于不同海洋环境的黑灰红三套岩层,利用微体古生物指标,对藏南晚白垩世海水氧含量变化进行了探讨。研究发现微体生物在不同性质的岩层中具有不同的表现,对其生存环境具有清楚的指示。黑层段中生物大量灭绝,深层水具旋脊有孔虫遭受的危机代表当时海洋深层水体严重缺氧的结果;灰层段中生物的恢复反映出海洋环境自缺氧事件之后逐步改善的过程;红层段属于富氧沉积的产物,特征是有孔虫生物的极度繁盛。同时期的钙质超微生物因其个体微小,易溶蚀,在死亡沉积过程中可能受海水强氧化作用的影响,使其保存为化石的数量减少。三套岩层中的微体生物的演变是对环境变化的响应。
|
| 关 键 词： | 藏南 晚白垩世 大洋氧含量 生物特征 |
| 文章编号： | 1005-2321(2005)02-0113-10 |
| 修稿时间： | 2004年12月20 |
Late Cretaceous biotic response to marine dissolved oxygen content in southern Tibet |
| |
| SI Jia-liang,GAO Lian-feng,WAN Xiao-qiao.Late Cretaceous biotic response to marine dissolved oxygen content in southern Tibet[J].Earth Science Frontiers,2005,12(2):113-122. |
| |
| Authors: | SI Jia-liang GAO Lian-feng WAN Xiao-qiao |
| |
| Abstract: | Southern Tibet is an ideal area for studying the marine Cretaceous in China. Based on the Zongshan Section of Gamba and the Chuangde Section of Gyangze, a black-gray-red bed sequence related to different marine environments has been recognized. In this paper, we discuss the oxygen content of the Late Cretaceous sea water by means of microfossil proxies. The composition of foraminifera and nano-fossils changed in accordance with the environmental variations in the sequence. It is suggested that the biotic extinction in the black unit was caused by the oceanic anoxic event at the C/T boundary, when the deep seawater was strongly anoxic. The gray unit reflects a recovery process of dissolved oxygen content, when the marine environment improved gradually. High abundance of the foraminifera and abnormal quantities of nano-fossils occurred in the red unit imply a highly oxidized marine environment. |
| |
| Keywords: | Late Cretaceous marine dissolved oxygen content biotic response southern Tibet |
| 本文献已被 CNKI 维普 万方数据 等数据库收录！ |
|
