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

这个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的波动而变化。特别是，它侧重于北海扇，这是位于前挪威海峡冰流头部的一个大型储藏中心，以及在扇的层状结构中发现的第四纪海底滑梯。其中最深、最古老的Std Slide由于其深度和缺乏足够高分辨率的地震数据，到目前为止一直被研究得很少。利用新的高分辨率数据集，本研究分析了Std Slide的形态和沉积学，以揭示该事件的触发因素、前提条件和机制，包括可能发生该事件的冰川条件。这将与扇内和更远的其他幻灯片进行比较，以揭示围绕巨型滑坡的更广泛的模式，以及它们与波动的冰盖边缘的关系。槽口扇(TMF)形成于冰槽的顶部，在那里快速流动的出口冰川(冰流)有效地侵蚀沉积物。这些沉积物在大陆斜坡上的冰流边缘被排出，形成一个进积的沉积物楔形。北海扇(NSF)位于挪威海峡的头部，在第四纪断断续续地承载着挪威海峡冰流，是一个TMF，在北欧海东南部的大陆斜坡上形成了一个主要的沉积中心。美国国家科学基金会32000千米的分层沉积记录包含了自早更新世开始以来的大量冰川和海洋条件信息。在国家科学基金会的结构中，已经发现了几个大规模的海底滑梯。快速的冰川沉积和间冰期“脆弱”沉积层的形成常常被认为是冰川边缘如此大的滑坡背后的机制。然而，目前对这类幻灯片的触发和进展的理解仍然存在差距。斯托雷加滑梯(8.1千亚)形成了最近的滑梯，在国家科学基金会东北方向的现代海底上可以看到。在埋藏的NSF层中还发现了三个：Tampen层(0.15Mya)、More(0.4Mya)和Std Slides(0.5Mya)。Std Slide形成了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)滑坡的详细研究还是不可能的。然而，新的高分辨率地震数据意味着，详细的分析现在是可行的。因此，这项研究的目的是对NSF巨型滑坡进行详细的分析，特别是STAD滑坡。这涉及到形态和沉积学分析，以揭示更多关于滑坡驱动因素和进程的信息，以及如何将其与冰盖行为联系起来，例如向TMF输送沉积物的方式和速度。与其他幻灯片的比较将揭示更多关于海底斜坡破坏的普遍和局部驱动因素和进展情况。该项目使用了来自东北大西洋边缘的大量地震数据集。地震数据成像埋藏的海底表面，不同沉积物类型之间的声学特征差异使其能够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。这项技术已被用于详细分析NSF和海底幻灯片，这类数据集在深度分辨率的提高现在使STAD幻灯片可以进行类似的分析。研究问题1)从STAD滑块的结构和形态可以推断出它的驱动因素和机制是什么？2)STAD滑块与NSF上的其他潜艇巨型滑块有什么不同和相似之处，这揭示了它们的相对驱动因素和性质？3)这些幻灯片可以揭示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?"