Boreal extinction and recovery patterns in the Permian of Spitsbergen

地质记录中的大灭绝塑造了地球上的进化和生命进程，没有它们，人类就不会存在。因此，了解导致大规模物种灭绝的原因是科学研究中最吸引人的话题之一。我们离解开这些古老的谋杀之谜还有很长的路要走。通过研究深层时间内重大变化的原因和后果，我们可以对当今的气候变化和影响地球上生命的问题有一个独特的视角。有史以来影响地球的两次最大的物种灭绝发生在1000万年之内，分别是在中二叠纪和二叠纪-三叠纪（PT）的交界处。后者导致95%的海洋物种死亡，是地质记录中最大的生命危机。这两次灭绝都发生在二叠纪赤道地区，可能的原因包括火山作用、海平面变化和海洋氧气消耗。然而，人们对中高纬度地区环境或动物变化的记录所知甚少，也不清楚低纬度地区损失的原因是否在其他地方起作用。这个项目将通过检查北极斯匹次卑尔根岛的二叠纪序列来验证这一点，那里的悬崖上暴露的海洋岩石包含了动物和环境变化的记录。在研究期间，斯匹次卑尔根位于北纬40-60度，远离赤道，位于北方海。由于无法准确确定岩石的年代，对该地区的研究受到了阻碍。因此，在北方王国的事件的相对年龄是不清楚的。已知岩石中含有丰富的化石，但它们对两次灭绝事件的反应尚不清楚。火山活动被认为是导致中国南方二叠纪中期物种灭绝的原因，但目前尚不清楚它的影响是否超出了中国大陆。海洋的变暖和缺氧是造成PT事件的因素，但北方海的冷水应该不那么容易受到影响（因为氧气在较低的温度下更容易溶解）。在两次物种灭绝之间，人们对北方生态系统的恢复知之甚少：生命是在PT边界被摧毁之前完全恢复的，还是那次危机如此严重，因为生态系统已经受到了早期事件的压力？提高对该地区动物丧失和恢复的认识将有助于我们评估相互竞争的灭绝机制。北纬记录与世界其他地区的对比是该项目成功的组成部分，并将利用化学地层学来实现。因此，我们将制作一条碳同位素曲线- -这条曲线最近已为其他地区建立，但尚未为斯匹次卑尔根建立。因此，该项目将：a)建立二叠纪年龄模型，使斯匹次卑尔根剖面能够在全球范围内进行对比；b)检查这段时间内环境和动物变化的记录。为了实现第二个目标，我们将采用多种技术：实地和显微镜检查化石，以确定灭绝和恢复的时间；层序地层学（反映海平面变化的岩石类型的变化）；分析岩石中的黄铁矿（以评估海洋氧含量的变化）。所有这些方法以前都被成功地使用过，但从未应用于北方王国的研究。这个项目的最终目的是确定北方地区的两次大规模灭绝事件，并确定它们的时间和原因。这将检验二叠纪期间赤道灭绝的驱动因素是否真的可以被认为是全球性的。研究结果将通过学术刊物向科学受众公布，并通过项目网站、学校外展活动和大众媒体向更广泛的受众公布。

Mass extinctions in the geological record have shaped the course of evolution and life on Earth, and without them, humans would not exist. Understanding what causes mass extinctions is therefore one of the most fascinating topics for scientific research. We are still a long way from solving these ancient murder mysteries. By studying the cause and consequence of major changes in deep time, we can gain a unique perspective on current-day climate change and the issues affecting life on Earth. Two of the biggest extinctions ever to affect the Earth occurred within 10 million-years of each other, in the Middle Permian and at the Permian-Triassic (PT) boundary. The latter event killed up to 95% of marine species and is the greatest crisis of life in the geological record. Both extinctions are well-known from Permian equatorial regions, where their probable causes include volcanism, sea-level change, and oceanic oxygen depletion. However, little is known of the record of environmental or faunal change in mid-high latitudes, and it is not clear whether the causes of low-latitude losses were operating elsewhere. This project will test this by examining superb Permian sequences from the Arctic island of Spitsbergen, where marine rocks are exposed in cliffs that contain a record of faunal and environmental change. During the study interval, Spitsbergen was located at 40-60 degrees north, far removed from equatorial settings, in the Boreal seas. Study in the region has been hampered by an inability to accurately date the rocks. Thus, the relative age of events in the Boreal realm is unclear. The rocks are known to contain abundant fossils but their response to the two extinction events is unknown. Volcanism is thought to have caused the Middle Permian extinction in South China, but it is not clear if its effects reached beyond that continent. Warming and lack of oxygen in the oceans are factors in the PT event, but the cool waters of the Boreal seas ought to have been less susceptible (because oxygen is more readily dissolved at lower temperatures). Little is known of the recovery of the Boreal ecosystem between the two extinctions: did life recovery fully before being devastated at the PT boundary, or was that crisis so severe because the ecosystem was already stressed by the earlier event? An improved understanding of faunal loss and recovery in the region will help us to evaluate the competing extinction mechanisms. The correlation of the Boreal record with other parts of the world is integral to the success of the project, and will be achieved using chemostratigraphy. Thus, we will produce a carbon isotope curve - which has recently been established for other regions but not yet for Spitsbergen. The project will therefore: a) develop a Permian age model, allowing Spitsbergen sections to be correlated globally; and b) examine the record of environmental and faunal change within that time framework. To achieve the second objective, we will employ a variety of techniques: field- and microscope examination of fossils to pinpoint the timing of extinction and recovery; sequence stratigraphy (changes in rock type that reflect changing sea-levels); and analysis of pyrite in the rocks (to assess changes in oceanic oxygen levels). All of these methods have been used successfully before, but have never been applied to studies of the Boreal realm. Ultimately this project aims to identify two mass extinction events in the Boreal realm, and to ascertain their timing and causes. This will test whether the drivers of equatorial extinctions during the Permian can truly be considered global. The results will be publicised to a scientific audience through the academic press, and to a wider audience via the project website, school outreach activities, and the mass media.