Isotopic evidence for temperature variation during the early Cretaceous (late Ryazanian–mid‐Hauterivian)
Isotopic evidence for temperature variation during the early Cretaceous (late Ryazanian–mid‐Hauterivian)
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DOI：
10.1144/jgs.157.2.335
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发表时间：
2000-03
影响因子：
2.7
通讯作者：
G. Price;A. Ruffell;C. E. Jones;R. Kalin;J. Mutterlose
中科院分区：
文献类型：
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作者：
G. Price;A. Ruffell;C. E. Jones;R. Kalin;J. Mutterlose
氧和碳同位素组成已被确定从belemnite属Acroteuthis和Hibolites采样从早白垩世（梁赞Hauterivian）间隔的Speeton粘土形成，Filey湾，英格兰。斯皮顿粘土组由一系列沉积于陆表海的粘土岩和钙质泥岩组成。符合保存完好的骨架碳酸盐岩石学和化学标准的碧流岩的δ 18 O值显示了温暖的海洋古温度（c. 12-15°C），而最早的奥特里阶则推断为低温（<9°C）。在豪特里维安的剩余时间里，气温波动很大，最高达到15.5°C。高岭石和蒙皂石丰度的变化被认为反映了气候的潮湿和干旱阶段，与温暖和凉爽的事件有关。古温度记录，似乎与头足类动物群的证据相矛盾，头足类动物群显示特提斯流入在推断早期奥特里温凉期。然而，这是一个海侵阶段，因此头足类动物可能对温度不太敏感，而对水柱稳定性和陆地屏障不太敏感。一个积极的转变，在碳同位素配置文件中获得的Speeton箭石出现可验证的碳同位素配置文件记录从远洋特提斯继承，虽然有一些不同的绝对值。这些数据支持早期的碳同位素变化模型，因为正偏移与推断的全球海平面上升有关。
Oxygen and carbon isotopic compositions have been determined from the belemnite genera Acroteuthis and Hibolites sampled from the early Cretaceous (Ryazanian–Hauterivian) interval of the Speeton Clay Formation, Filey Bay, England. The Speeton Clay Formation consists of a series of claystones and calcareous mudrocks deposited in an epicontinental sea. δ18O values from belemnites, which met petrographic and chemical criteria for well preserved skeletal carbonate, indicate warm marine palaeotemperatures (c. 12–15°C) for much of the early Valanginian whilst cool temperatures (<9°C) are inferred for the earliest Hauterivian. During the remainder of the Hauterivian, temperatures fluctuated considerably and rose to a maximum of 15.5°C. Changes in kaolinite and smectite abundances, considered to reflect humid and arid phases of climate, correlate with warm and cool episodes. The palaeotemperature record, appears to contradict evidence from cephalopod faunas, which show a Tethyan influx during the inferred early Hauterivian cool period. However, this was a transgressive phase and thus the cephalopods could have been less sensitive to temperature than to water column stability and to land barriers. A positive shift in the carbon isotope profile obtained from the Speeton belemnites appears correlatable with carbon isotope profiles recorded from pelagic Tethyan successions, albeit with somewhat differing absolute values. The data support earlier models of carbon isotope variation, in that positive excursions are associated with an inferred global rise in sea level.