The Geological Record of Continental Seasonality

在全球变暖时期（白垩纪至始新世），温暖气候的动植物分布在古高纬度地区，这是证明大型大陆内部季节性温度变化范围减小的主要标准。然而，这种解释与基于能量平衡和环流气候模式的预测相冲突。根据模拟研究，与高纬度海洋变暖期间温暖而稳定的海洋和沿海环境相反，大陆内部应保持广泛的季节性温度变化。作为对这一假设的检验，本研究将利用化石海洋和非海洋双壳类的del 18O变化，提供北美大陆内部存在的最小季节温度变化的定量测量。取样技术的进步现在允许对双壳类存在的增生生长结构进行微观分析，时间分辨率为每周到次月。对这些序列地层数据的评估将限制北美内部从晚白垩纪到晚始新世的季节性和年平均温度的时间变化。

The distribution of warm-climate flora and fauna to high paleolatitudes during times of global warming (Cretaceous through Eocene) is a prime criterion arguing for a decreased range in seasonal temperature variation for the interiors of large continents. Such interpretations, however, are in conflict with predictions based on Energy Balance and General Circulation Climate Models. According to modeling studies, in contrast to warm and equable oceanic and coastal environments during periods of high latitude warming of the ocean, continental interiors should retain a wide range of seasonal temperature variation. As a test of this hypothesis, this study will provide quantitative measures of minimum seasonal temperature variation present within the continental interior of North America utilizing del 18O variation in fossil marine and non-marine bivalves. Advances in sampling techniques now permit microanalysis of the accretionary growth structure present in bivalves, with a time resolution of weekly to submonthly intervals. Evaluation of these data from sequential stratigraphic levels will constrain temporal changes in seasonality and mean annual temperature in the interior of North America from late Cretaceous to late Eocene times.