Cretaceous-Palaeogene ocean and climate change in the subtropical North Atlantic
Cretaceous-Palaeogene ocean and climate change in the subtropical North Atlantic
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白垩纪-古近纪海洋与北大西洋副热带气候变化
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发表时间：
2001
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影响因子：
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通讯作者：
J. Erbacher
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作者：
R. Norris;D. Kroon;B. Huber;J. Erbacher
海洋钻探计划（ODP） Leg 171B恢复了连续序列，为地球历史上一系列“关键”事件提供了证据。主要事件包括始新世晚期放射虫灭绝、与晚古新世热极大期（LPTM）相关的晚古新世底栖有孔虫灭绝、白垩纪-古近纪（K-P）灭绝、中马斯垂斯事件以及记录晚塞诺曼世、晚阿尔比世和早阿尔比世暖期的几期火山冲积物沉积。legal171b遗址有孔虫稳定同位素结果汇编和先前发表的记录显示，从阿尔比世到始新世晚期，温度和δ13C趋势发生了一系列大规模的循环。浮游和底栖有孔虫之间的δ18O梯度演化表明，北大西洋从早期阿尔比世类似于现代地中海的环流系统演变为阿尔比世晚期-早期塞诺曼尼亚的更开放的海洋环流系统。海洋表面温度在白垩纪中期气候最佳时期达到峰值，从阿尔巴尼亚-塞诺曼尼亚边界到Coniacian时代，然后呈现出向马斯特里希特中部凉爽气候下降的趋势。Albian-Coniacian期的特征是浅底栖氧同位素值显示普遍温暖的深水。最轻的底栖动物氧同位素出现在Cenomanian-Turonian边界附近，表明北大西洋温度高达20°C的中深海水域。在Turonian时期大范围的冲积物的消失表明，将北大西洋与全球海洋其他部分分开的屏障最终被突破到足够的深度，从而允许从其他地方流入的深水进行通风。马斯特里赫特和古近纪记录显示了马斯特里赫特-达尼世晚期和古新世晚期-始新世早期两次大规模的碳埋藏和采掘。碳埋藏在大年代早期达到顶峰，这可能是对欧洲和北美大陆表层海洋撤出的反应。随后的大年期大部分时间都用于清除先前沉积的碳，并修复K-P大灭绝对深海碳输出系统造成的破坏。最年轻的一次碳发掘与始新世早期暖期和LPTM的开始一致，并归因于特提斯东部的构造闭合和喜马拉雅造山运动的开始。
Abstract Ocean Drilling Program (ODP) Leg 171B recovered continuous sequences that yield evidence for a suite of ‘critical’ events in the Earth’s history. The main events include the late Eocene radiolarian extinction, the late Palaeocene benthic foraminiferal extinction associated with the Late Palaeocene Thermal Maximum (LPTM), the Cretaceous-Palaeogene (K-P) extinction, the mid-Maastrichtian event, and several episodes of sapropel deposition documenting the late Cenomanian, late Albian and early Albian warm periods. A compilation of stable isotope results for foraminifera from Leg 171B sites and previously published records shows a series of large-scale cycles in temperature and δ13C trends from Albian to late Eocene time. Evolution of δ18O gradients between planktic and benthic foraminifera suggests that the North Atlantic evolved from a circulation system similar to the modern Mediterranean during early Albian time to a more open ocean circulation by late Albian-early Cenomanian time. Sea surface temperatures peaked during the mid-Cretaceous climatic optimum from the Albian-Cenomanian boundary to Coniacian time and then show a tendency to fall off toward the cool climates of the mid-Maastrichtian. The Albian-Coniacian period is characterized by light benthic oxygen isotope values showing generally warm deep waters. Lightest benthic oxygen isotopes occurred around the Cenomanian-Turonian boundary, and suggest middle bathyal waters with temperatures up to 20 °C in the North Atlantic. The disappearance of widespread sapropel deposition in Turonian time suggests that sills separating the North Atlantic from the rest of the global ocean were finally breached to sufficient depth to permit ventilation by deep waters flowing in from elsewhere. The Maastrichtian and Palaeogene records show two intervals of large-scale carbon burial and exhumation in the late Maastrichtian-Danian and late Palaeocene-early Eocene. Carbon burial peaked in early Danian time, perhaps in response to the withdrawal of large epicontinental seas from Europe and North America. Much of the succeeding Danian period was spent unroofing previously deposited carbon and repairing the damage to carbon export systems in the deep ocean caused by the K-P mass extinction. The youngest episode of carbon exhumation coincided with the onset of the early Eocene Warm Period and the LPTM, and has been attributed to the tectonic closure of the eastern Tethys and initiation of the Himalayan Orogeny.