摘要
从“海源陆生化石”、壳体O、C和S同位素等几个新的角度和方法对山东东营凹陷古近纪古湖泊湖水化学性质进行讨论。通过与现生“海源陆生生物”的比较 ,得出原先认为是“海相”标志的有孔虫、钙质超微化石、沟鞭藻和疑源类、多毛类和鱼类等实际上是“海源陆生化石” ,它们生活在以Cl-和Na+ 为主的咸水湖泊环境。超微化石S同位素分析表明 ,渐新世与始新世钙质超微化石的87Sr/ 86Sr比值都明显高于同时期海水的87Sr/ 86Sr比值 ,而与现代河、湖水的87Sr/ 86Sr比值相近 ,进一步揭示它们生活的环境不是海 ,而是与海无关的湖。介形虫壳体O、C同位素分析则表明 ,古东营湖是一封闭型咸水湖泊 ,从另一角度也否定了与海连通的可能性。根据不同层段同位素特征讨论了湖水矿化度的相对变化。
Water chemistry of the Paleogene Lake existent in Dongying depression of Shandong Province has been discussed by means of several new methods including talassogenous fossils, oxygen, carbon and strontium isotope of fossils. Foraminifera, calcareous nannofossils, dinoflagellates and acritarchs, fish and other groups of 'marine type fossils' were discovered in Paleogene sediments from Dongying depression and were then used as the indicators of marine transgression. Comparing them with modern talassogenous fauna, the authors have reached the conclusion that these fossils are talassogenous in nature and lived in the saline lake rich in Na and Cl. Strontium isotopic analysis indicates that 87 Sr/ 86 Sr ratios of nannofossils from Eocene and Oligocene sediments are higher than those of sea water of the same periods, and are close to the 87 Sr/ 86 Sr ratios of modern river and lake water. These results imply that nannofossils lived in a paleolake rather than in seawater. Carbon and oxygen isotopic analysis also demonstrates that the Paleogene Dongying Lake was a hydrologically closed lake. Variations in paleosalinity have also been discussed based on the stratigraphic changes of δ 18 O and δ 13 C.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2002年第3期237-242,共6页
Acta Geoscientica Sinica
基金
教育部高等学校骨干教师资助计划
教育部重大科学技术"中国新生代地形倒转及资源环境效应"项目资助
关键词
化石群
壳体
同位素
古近纪
东营湖
湖水化学
talassogenous fssils isotope water chemistry Paleogene Dongying depression
