Abstract International Ocean Discovery Program drilling in the Great Australian Bight (Site U1512) provides a record of Turonian to Santonian hemipelagic sedimentation deposited in an elongate epicontinental basin that opened westward to the Southern Ocean during the peak and the early decline of the Cretaceous hot greenhouse. Despite its relatively high paleolatitude (at about 60°S), the biostratigraphy of calcareous nannofossils from this succession is directly correlative to low-latitude zonation schemes throughout the Turonian to Santonian. These calcareous nannofossil assemblages are somewhat restricted in species composition, lacking some elements generally found in Late Cretaceous assemblages (e.g., holococcoliths). In addition, two biostratigraphically-important high latitude taxa (Thiersteinia ecclesiastica, and Zeugrhabdotus kerguelenesis) have biostratigraphic ranges notably shorter than elsewhere, indicating range truncation through local extirpation. Quantitative paleoecological analysis of the calcareous nannofossil assemblages indicates that the major change in the paleoenvironment was the evolution from conditions that were quite warm and had relatively elevated surface water fertility in the Turonian to cooler and possibly more oligotrophic conditions in the Coniacian–Santonian. The first cooling began at about 92 Ma, accelerated at about 91.2 Ma and then continued to gradually cool during the Coniacian–Santonian. This paleotemperature scenario is consistent with those documented from other localities globally.

中文翻译：

---

来自大澳大利亚湾（IODP Site U1512）的钙质纳米化石记录了白垩纪中期超级温室的高峰和早期衰退

摘要 国际大洋发现计划在大澳大利亚湾（U1512 站点）的钻探记录了土伦阶到桑顿阶半远洋沉积物，沉积在一个细长的陆上盆地中，该盆地在白垩纪热温室的高峰和早期衰退期间向西开放至南大洋。尽管其古纬度相对较高（约 60°S），但来自该系列的钙质纳米化石的生物地层与整个土伦阶到桑托阶的低纬度分区方案直接相关。这些钙质纳米化石组合在物种组成方面受到一定限制，缺乏通常在晚白垩世组合中发现的一些元素（例如，holococcoliths）。此外，两个生物地层学上重要的高纬度分类群（Thiersteinia ecclesiastica，和 Zeugrhabdotus kerguelenesis) 的生物地层范围明显短于其他地方，表明由于局部灭绝而导致范围被截断。对钙质纳米化石组合的定量古生态分析表明，古环境的主要变化是从土伦阶相当温暖且地表水肥力相对较高的条件演变为康尼亚-桑托阶中较冷且可能更加贫营养的条件。第一次冷却开始于大约 92 Ma，在大约 91.2 Ma 加速，然后在 Coniacian-Santonian 期间继续逐渐冷却。这种古温度情景与全球其他地方记录的情景一致。对钙质纳米化石组合的定量古生态分析表明，古环境的主要变化是从土伦阶相当温暖且地表水肥力相对较高的条件演变为康尼亚-桑托阶中较冷且可能更加贫营养的条件。第一次冷却开始于大约 92 Ma，在大约 91.2 Ma 加速，然后在 Coniacian-Santonian 期间继续逐渐冷却。这种古温度情景与全球其他地方记录的情景一致。对钙质纳米化石组合的定量古生态分析表明，古环境的主要变化是从土伦阶相当温暖且地表水肥力相对较高的条件演变为康尼亚-桑托阶中较冷且可能更加贫营养的条件。第一次冷却开始于大约 92 Ma，在大约 91.2 Ma 加速，然后在 Coniacian-Santonian 期间继续逐渐冷却。这种古温度情景与全球其他地方记录的情景一致。