Polar Terrestrial Climate During the Coniacian Age (Middle Late Cretaceous)

阿拉斯加北坡王子溪组的图鲁瓦克舌，包含了最高纬度的Coniacian（中晚白垩纪）时代的植物群。初步研究表明，这里的植物群可能是一个混合针叶林，其中包含了多种被子植物。被子植物叶缘分析可以提供年平均气温的定量信息。通过分析植被地貌（受气候强烈控制的植被的总体方面）和化石木材的生长年轮特征，特别是如果这些特征可以与下面和上面的植物区系进行比较，就可以支持温度估计。因此，图鲁瓦克舌的植物区系提供了量化柯尼西亚时代近极地陆地温度的机会。根据来自低纬度海洋化石的同位素证据，Coniacian可能是晚白垩纪的热最大值，因此了解当时极地地区的气候尤为重要。此外，将Tuluvak植物区系与Albian-Cenomanian Niakogon舌（Chandler组）和Campanian-Maastrichtian Kogosukruk舌（Prince Creek组）的植物区系进行比较，将有助于确定在数据分辨率范围内，北极附近的气候变化是否与在低纬度观测到的变化是同步的。从图鲁瓦克舌收集到的信息不仅可以用来帮助建立柯尼西亚时代的纬向温度梯度，而且还将完成该地区较早和较年轻的植物区系已经确定的近极气候变化历史。

The Tuluvak Tongue of the Prince Creek Formation, North Slope of Alaska, contains the highest-latitude flora of Coniacian (middle Late Cretaceous) age. Preliminary work suggests that the flora probably represents a mixed coniferous forest, and that it contains a diverse assemblage of angiosperms. Leaf-margin analysis of angiosperms can provide quantitative information on mean annual temperature. The temperature estimates can be supported by analysis of the vegetational physiognomy (overall aspect of the vegetation, which is strongly controlled by climate) and of the growth-ring characteristics in fossil wood, particularly if these characteristics can be compared with those of under= and overlying floras. Thus, the flora of the Tuluvak Tongue provides the opportunity to quantify near-polar terrestrial temperatures for the Coniacian Age. Because the Coniacian may have been a thermal maximum in the Late Cretaceous, based on isotopic evidence from marine fossils at lower latitudes, it is particularly important to understand the climate in polar regions for that time. In addition, comparison of the Tuluvak flora with the floras of the Albian-Cenomanian Niakogon Tongue (Chandler Formation) and Campanian-Maastrichtian Kogosukruk Tongue (Prince Creek Formation) will help determine whether climate change near the North Pole was synchronous, within the resolution of the data, with the changes observed at lower latitudes. The information gathered from the Tuluvak Tongue can be used not only to help establish latitudinal temperature gradients for the Coniacian Age, but also will complete the history of near-polar climate change already determined from older and younger floras in the region.