Late Cretaceous Temperature Evolution of the Southern High Latitudes: A TEX 86 Perspective
Late Cretaceous Temperature Evolution of the Southern High Latitudes: A TEX 86 Perspective
复制标题
南部高纬度地区的晚白垩世温度演化：TEX 86 视角
DOI：
10.1029/2018pa003546
复制
发表时间：
2019
影响因子：
3.5
通讯作者：
O'Connor L
中科院分区：
文献类型：
--
作者：
O'Connor L
白垩纪晚期是一个温室世界，其特点是气温升高和大气中二氧化碳浓度较高。即使在极端温室气候的背景下，来自福克兰高原（古纬度约 55°S）的现有浮游有孔虫 δ18O 数据也表明异常温暖，白垩纪晚期的大部分时间海面温度 (SST) >30°C，随后坎帕尼亚突然变冷。在过去的二十年里，人们一直在讨论这些基于 δ18O 的高海温是否反映了真实的温度信号，如果是的话，南大西洋是否存在局部温度异常，或者这些数据是否代表南纬 55° 的地带性古温度。为了对白垩纪晚期（塞诺曼阶到坎帕阶）南部高纬度地区海洋变暖程度提供新的见解，这里使用有机地球化学古温度计 86 个碳原子的 TetraEther 指数 (TEX86) 提供了福克兰高原和凯尔盖朗高原的新海表温度记录。总体而言，TEX86数据支持δ18O数据，表明晚白垩世南半球中高纬度地区出现极端且广泛的温暖，海温为27至37°C。至关重要的是，TEX86 数据显示从土伦纪到坎帕阶的缓慢而稳定的冷却，表明坎帕阶期间的温度梯度并没有像一些浮游有孔虫数据所暗示的那样陡峭。
The Late Cretaceous was a greenhouse world, characterized by elevated temperatures and high atmosphericpCO2. Even in the context of an extreme greenhouse climate, existing planktic foraminiferal δ18O data from the Falkland Plateau (paleolatitude of ~55°S) suggest anomalous warmth, with sea‐surface temperatures (SSTs) >30 °C for much of the Late Cretaceous, followed by sudden cooling in the Campanian. Over the last two decades, there has been discussion as to whether these high δ18O‐based SSTs reflect a genuine temperature signal and, if so, whether there was a local temperature anomaly in the South Atlantic or whether the data are representative of zonal paleotemperatures at 55°S. To provide new insights into the degree of ocean warming in the southern high latitudes during the Late Cretaceous (Cenomanian to Campanian), new SST records from the Falkland and Kerguelen Plateaus are presented here using the organic geochemical paleothermometer TetraEther indeX of 86 carbon atoms (TEX86). Overall, the TEX86data support the δ18O data, indicating extreme and widespread warmth in the middle to high southern latitudes in the Late Cretaceous, with SSTs from 27 to 37 °C. Crucially, the TEX86data show slow, steady cooling from the Turonian to the Campanian and suggest that temperature gradients during the Campanian did not become as steep as suggested by some planktic foraminiferal data.