白亜紀海洋無酸素事変
- 標題
- 白亜紀海洋無酸素事変
- 作者
- 平野 弘道, 安藤 寿男
- 文件屬性
- 日本研究
- 知識分類
- 基礎研究
- 出版年
- 2006
- 刊名
- 石油技術協会誌
- 卷
- 71
- 期
- 3
- 頁
- P 305-315
- 點閱數
- 4867
摘要
Thirty years passed since the Cretaceous Oceanic Anoxic Events were proposed by Schlanger and Jenkyns (1976). Three events, OAE1 to 3 were recognized at the beginning of the research. Nowadays, however, OAE1 is subdivided into four subevents, OAE1a, b, c, and d. The OAE1b subevent is further subdivided into three components, Jacob, Paquier, and Leenhardt. The existence of Mid-Cenomanian Event (MCE) between OAE1d and OAE2 is drawing attentions of world scientists. A concise review of the researches on these events and subevents is followed by more detailed descriptions of the synonymy (local names), geographic distribution, age, stable carbon isotope fluctuations, extinction and/or radiation of fossils, major synchronous events, characteristics including the duration and the types of kerogen, and their causal factors. It is recognized that all OAEs do not have the same causal factor. The western part of the Tethys and the narrower early Atlantic were rather closed basins, where anoxic to dysoxic conditions easily occurred through the stratification of water column by run off, like the Sapropel event 1 in the Holocene Mediterranean Sea. The Cretaceous global OAEs may have occurred either by the stagnation of the deep water associated with the global warming or by propagation of marine organisms. Due to a large amount of input of terrestrial siliciclasitics, the regional influence of OAEs in the Japanese Cretaceous strata may differ from that of the Tethyan/Atlantic region, even if the occurrence of OAEs is ocean wide or globally synchronous.