Determining the drivers and mechanisms of Quaternary submarine megaslides on the North Sea Fan using high-resolution seismic datasets

“该项目使用覆盖东北大西洋边缘的地震数据集来分析冰川沉积如何随着冰盖边缘波动而变化。特别是，它侧重于北海扇，在前挪威海峡冰流的头部的大型沉积中心，和第四纪海底幻灯片，已确定的分层结构内的风扇。其中最深和最古老的是Stad Slide，由于其深度和缺乏足够高分辨率的地震数据，迄今为止对其研究甚少。利用新的高分辨率数据集，本研究分析了Stad Slide的形态学和沉积学，以揭示更多关于事件的触发因素，先决条件和机制，包括可能的冰川条件。这将与风扇内的其他幻灯片和更远的地方进行比较，以揭示更广泛的模式周围megaslides和他们的关系波动冰盖边缘。槽口扇（TMF）形成于冰川槽的顶部，快速流动的出口冰川（冰流）有效地侵蚀沉积物。这些沉积物在大陆坡的冰流边缘被排出，形成沉积物的横向楔。北海扇（NSF）位于挪威海峡的顶端，在第四纪期间间歇性地容纳了挪威海峡冰流，是一个在东南北欧海大陆坡上形成主要沉积中心的冰丘。国家科学基金会的32,000立方公里的分层沉积记录包含了大量关于早更新世以来冰川和海洋状况的信息。在NSF的结构中，已经确定了几个大规模的海底滑坡。快速的冰川沉积与间冰期“软弱”沉积层的形成经常被认为是冰川边缘如此大规模滑坡背后的机制。然而，目前对这些幻灯片的触发因素和进展的理解仍然存在差距。Storegga Slide（8.1kya）是最新的，在NSF东北部的现代海底可见。另外三个已被确定在埋NSF层：坦彭（0.15 Mya），更多（0.4 Mya）和斯塔德幻灯片（0.5 Mya）。Stad Slide是NSF中最深也可能是最大的滑梯。直到最近，对这种深（海底以下700- 1000米）滑坡的详细研究一直是不可能的。然而，新的高分辨率地震数据意味着现在可以进行详细的分析。因此，本研究旨在对NSF megaslides进行详细分析，特别关注Stad Slide。这涉及形态学和沉积学分析，以揭示更多关于滑坡驱动因素和进展的信息，以及这如何与冰盖行为联系起来，例如沉积物输送到TMF的模式和速度。与其他幻灯片的比较将揭示更多关于海底边坡破坏的普遍和局部驱动因素和进展。该项目使用了来自东北大西洋边缘的大量地震数据集。地震数据可对埋藏的海底表面进行成像，不同沉积物类型之间的声学特征存在差异，从而可以重建过去的沉积作用。地震地貌学可以揭示更大规模的模式，例如通过识别指示冰川活动的埋藏地貌。这种技术已被用于详细分析NSF和海底幻灯片，并且这些数据集的深度分辨率的增加现在使Stad幻灯片开放给类似的分析。1）从Stad Slide的结构和形态可以推断出什么关于其驱动因素和机制？2)Stad Slide和NSF上的其他海底巨型滑梯之间有什么区别和相似之处，这揭示了它们的相对驱动因素和性质？3)这些幻灯片能揭示什么关于欧亚冰盖第四纪的波动？"

"This project uses seismic datasets covering the Northeast Atlantic Margin to analyse how glacial sedimentation changes with ice sheet margin fluctuations. In particular, it focuses on the North Sea Fan, a large depocentre at the head of the former Norwegian Channel Ice Stream, and the Quaternary Period submarine slides that have been identified within the layered structure of the fan. The deepest and oldest of these, the Stad Slide, has been poorly studied until now as a result of its depth and a lack of high enough resolution seismic data. Making use of new high-resolution datasets, this study analyses the morphology and sedimentology of the Stad Slide to reveal more about the triggers, preconditions, and mechanisms of the event, including the glacial conditions under which it was possible. This will be compared to other slides within the fan and further afield to reveal broader patterns surrounding megaslides and their relation to fluctuating ice sheet margins. Trough mouth fans (TMFs) form at the head of glacial troughs, where fast-flowing outlet glaciers (ice streams) efficiently erode sediment. This sediment is expelled at the ice stream margin on the continental slope, forming a progradational wedge of sediment. The North Sea Fan (NSF), at the head of the Norwegian Channel, which during the Quaternary intermittently hosted the Norwegian Channel Ice Stream, is a TMF which forms a major depocentre on the continental slope of the southeast Nordic Sea. The 32,000km3 layered sedimentary record the NSF contains hosts a wealth of information on glacial and oceanic conditions since its early Pleistocene inception. Within the structure of the NSF, several large-scale submarine slides have been identified. Rapid glacial sedimentation combined with formation of interglacial "weak" sedimentary layers are often cited as the mechanisms behind such large slides on glacial margins. However, there are still gaps in current understanding of the triggers and progression of such slides. The Storegga Slide (8.1kya) forms the most recent and is visible on the modern-day seafloor to the northeast of the NSF. Three more have been identified within buried NSF layers: the Tampen (0.15Mya), More (0.4Mya), and Stad Slides (0.5Mya). The Stad Slide forms the deepest and possibly largest slide in the NSF. Until recently detailed study of this deep (700-1000m below the seafloor) slide has been impossible. However, new high-resolution seismic data means that detailed analysis is now feasible. This research therefore aims to perform a detailed analysis of the NSF megaslides, with a particular focus on the Stad Slide. This involves morphological and sedimentological analysis to reveal more about slide drivers and progression, and how this can be linked to ice sheet behaviour, such as the mode and pace of sediment delivery to TMFs. Comparison with other slides will reveal more about the universal and local drivers and progression of submarine slope failures. The project uses extensive seismic datasets from the Northeast Atlantic Margin. Seismic data image buried seafloor surfaces, with the differences in acoustic signature between different sediment types allowing reconstructions of past sedimentation. Seismic geomorphology can reveal larger-scale patterns, for example by identifying buried landforms indicative of glacial activity. This technique has been used to analyse the NSF and submarine slides in detail, and the increasing resolution at depth of such datasets now renders the Stad Slide open to similar analysis. Research Questions1) What can be inferred from the structure and morphology of the Stad Slide about its drivers and mechanisms?2) What differences and similarities are there between the Stad Slide and other submarine megaslides on the NSF, and what does this reveal about their relative drivers and nature?3) What can these slides reveal about Quaternary fluctuations in the Eurasian Ice Sheet?"