PDF(Pubmed)
Abstract：
The Late Cretaceous was a unique period in the history of the Earth characterized by elevated sea levels, reduced land area, and significantly high concentrations of atmospheric CO2 resulting in increased temperatures across the globe-a \'Greenhouse World\'. During this period, calcareous dinoflagellate cysts (c-dinocysts) flourished and became a ubiquitous constituent of calcifying plankton around the world. An acme in calcareous dinocysts during the Albian to the Turonian coincided with the highest recorded seawater surface temperatures and was possibly linked to conditions that favored calcification and a highly oligotrophic system in European shelf seas. This study examines the potential applicability of c-dinocysts as a proxy for paleoenvironmental conditions based on their assemblage changes plotted against foraminiferal occurrences and microfacies analysis. The material was extracted from the upper Turonian chalk of the Dubivtsi region in western Ukraine. An inverse correlation was observed between species diversity and the number of c-dinocyst specimens. Nutrient availability gradients apparently determined important changes in the calcareous dinocysts distribution. These trophic changes were likely caused by the interplay of eustatic sea-level fluctuations and Subhercynian tectonic activity leading to changeable nutrient inputs from the nearby land.
摘要：
晚白垩纪是地球历史上一个以海平面升高为特征的独特时期,土地面积减少,和显著高浓度的大气二氧化碳导致全球气温升高-一个“温室世界”。在此期间,钙质鞭毛藻囊肿（c-dinocysts）蓬勃发展，并成为世界各地钙化浮游生物的普遍存在成分。在Albian至Turonian期间，钙质食性食囊中的极峰与记录到的最高海水表面温度相吻合，并且可能与有利于钙化和欧洲陆架海域高度贫营养系统的条件有关。这项研究根据对有孔虫发生和微相分析绘制的组合变化，研究了c-dinocuss作为古环境条件替代的潜在适用性。该材料是从乌克兰西部Dubivtsi地区的上Turonian粉笔中提取的。在物种多样性与c-dinocust标本数量之间观察到负相关。养分利用度梯度显然决定了钙质膀胱分布的重要变化。这些营养变化可能是由欣喜的海平面波动和Subhercynian构造活动的相互作用引起的，导致附近土地的养分输入不断变化。
