Stable isotope record of Maestrichtian foraminifera

A global compilation of deep-sea isotopic records suggests that Maastrichtian ocean-climate evolution was technically driven. During the early Maastrichtian the Atlantic intermediate-deep ocean was isolated from the Pacific, Indian, and Southern Oceans; deep water formed in the high-latitude North Atlantic and North Pacific. At the early/late Maastrichtian boundary a major reorganization of oceanic circulation patterns occurred, resulting in the development of a thermohaline circulation system similar to that of the modern oceans. A combination of isotopic and plate kinematic data suggests that this event was triggered by the final breaching of tectonic sills in the South Atlantic and the initiation of north-south flow of intermediate and deep water in the Atlantic. The onset of Laramide tectonism during the mid Maastrichtian led to the concurrent draining of major epicontinental seaways. Together, these events caused cooling, increased latitudinal temperature gradients, increased ventilation of the deep ocean, and affected a range of marine biota.一项基于全球深海同位素记录汇编的研究表明，马斯特里赫特阶（Maastrichtian）的海洋气候演化受构造作用驱动。马斯特里赫特阶早期，大西洋中深海水域与太平洋、印度洋及南大洋相互隔绝，高纬度北大西洋和北太平洋区域形成了深水水体。在马斯特里赫特阶早-晚交界时期，大洋环流格局发生重大重组，形成了与现代海洋相似的温盐环流（thermohaline circulation）系统。同位素与板块运动学数据的综合分析显示，该环流重组事件由南大西洋构造岩槛（tectonic sills）的最终贯通所触发，并伴随大西洋中深层水南北向流动的启动。马斯特里赫特阶中期，拉拉米构造运动（Laramide tectonism）的启动导致主要陆表海道同步干涸。上述一系列事件共同引发了气候变冷、纬向温度梯度增大、深海通风作用增强，并对诸多海洋生物类群产生了影响。