Jurassic climate mode governed by ocean gateway.
Jurassic climate mode governed by ocean gateway.
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DOI：
10.1038/ncomms10015
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发表时间：
2015-12-11
影响因子：
16.6
通讯作者：
Thibault N
中科院分区：
文献类型：
--
作者：
Korte C;Hesselbo SP;Ullmann CV;Dietl G;Ruhl M;Schweigert G;Thibault N
侏罗纪（∼201–145 Myr前）长期以来被认为是一个温暖的“温室”时期；最近很酷，甚至还假设了“冰屋”情节。然而，控制所谓的暖模式和冷模式之间的转换的机制却鲜为人知。在这里，我们提出了一个新的大型高质量氧同位素数据集，其中包括之前建议的模式转换。我们的结果显示，在南北劳亚海道（连接赤道特提斯洋和北海的海洋通道）中，最早的中侏罗世（∼174Ma）中纬度海水特别突然冷却了10°C。与北海地区大规模区域性岩石圈隆起的时间惊人地一致，我们假设向北的海洋热量输送受到隆起的阻碍，从而更广泛地引发了冷模式条件。这种极端气候模式的转变为与大气温室气体含量的数量变化相关的其他中生代转变提供了反例。 劳亚海道的动力学被认为对中生代中期的海洋学和气候产生了广泛的影响。在这里，作者展示了海水温度变化的证据，归因于构造隆升阻碍了向极地的海洋热量输送，并在最早的中侏罗世引发了凉爽的气候模式。
The Jurassic (∼201–145 Myr ago) was long considered a warm ‘greenhouse' period; more recently cool, even ‘icehouse' episodes have been postulated. However, the mechanisms governing transition between so-called Warm Modes and Cool Modes are poorly known. Here we present a new large high-quality oxygen-isotope dataset from an interval that includes previously suggested mode transitions. Our results show an especially abrupt earliest Middle Jurassic (∼174 Ma) mid-latitude cooling of seawater by as much as 10 °C in the north–south Laurasian Seaway, a marine passage that connected the equatorial Tethys Ocean to the Boreal Sea. Coincidence in timing with large-scale regional lithospheric updoming of the North Sea region is striking, and we hypothesize that northward oceanic heat transport was impeded by uplift, triggering Cool Mode conditions more widely. This extreme climate-mode transition provides a counter-example to other Mesozoic transitions linked to quantitative change in atmospheric greenhouse gas content. Dynamics of the Laurasian Seaway are thought to have had wide effects on oceanography and climate in the mid-Mesozoic. Here, the authors show evidence for seawater temperature change, ascribed to tectonic uplift that impeded poleward oceanic heat transport and triggered a cool climate mode in the earliest Middle Jurassic.