Middle Cretaceous abnormal geological events and global change
Middle Cretaceous abnormal geological events and global change
复制标题
作者：
HU Xiu-mian
中白垩世（125~90 Ma）是中生代最温暖的温室气候期之一，以异常的岩浆事件、大洋缺氧、生物更替和物质迁移、正常超时和大洋红层为特征。这些地质事件是岩石圈、生物圈和大气相互作用的结果。每一次地质事件都会引起一种特殊的全球变化，这种变化将通过一个积极或消极的反馈系统在产生其他事件方面发挥重要作用。本文着重介绍了这些地质事件及其引起的全球变化，特别是气候-海洋系统。并对这些地质事件在中白垩世的潜在联系和反馈机制进行了探讨。结果表明，大火成岩省的侵位等火成岩事件是通过CO_2的释放而导致异常海洋气候和温室气候的主要动力，并进一步加速了海洋缺氧、生物群的形成和沉积记录性质的改变。
The Mid-Cretaceous (125~90 Ma) was one of the warmest greenhouse climate periods of the Phanerozoic, and was characterized by extraordinary igneous events, oceanic anoxia, biotic turnovers and mass extinctions, normal superchron, and oceanic red beds. These geological events were the results of the interactions between the lithosphere, the biosphere and the atmosphere. Each geological event would give rise to a special global change which would play an important role in engendering other events through a system of positive or negative feedbacks. This paper focuses on the introduction of these geological events, the global changes that they caused, and especially climate-ocean system. A special effort is given to the potential linkage and feedback mechanism of these geological events in the the Mid-Cretaceous. It is concluded that the igneous events, such as the emplacement of Large Igneous Provinces were the primary force to cause the abnormal ocean and greenhouse climate through outgas of CO_2, which would have further accelerated the formation of the oceanic anoxia, biotic mass extinctions, and a change in the nature of the sedimentary record.