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

使用高分辨率地震数据集确定北海扇第四纪海底巨型滑坡的驱动因素和机制

• 批准号: 2748228
• 金额: --
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2748228
• 关键词: Determining; drivers; mechanisms; Quaternary; submarine

"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?"

“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。它特别关注北海扇，这是前挪威海峡冰流头部的一个大型沉积中心，以及在扇的分层结构中发现的第四纪海底滑坡。其中最深、最古老的是斯塔德滑坡，由于其深度和缺乏足够高分辨率的地震数据，迄今为止人们对它的研究很少。利用新的高分辨率数据集，本研究分析了斯塔德滑坡的形态和沉积学，以揭示更多关于该事件的触发因素、先决条件和机制，包括可能发生的冰川条件。这将与扇内和更远的地方的其他滑动进行比较，以揭示围绕巨型滑动的更广泛的模式及其与波动的冰盖边缘的关系。槽口扇（TMFs）在冰川槽的顶部形成，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的冰流边缘被排出，形成沉积物的递进楔。北海扇（NSF）位于挪威海峡的前端，在第四纪间歇地容纳了挪威海峡冰流，是一个在北欧海东南部大陆斜坡上形成主要沉积中心的TMF。NSF包含的32,000km3层状沉积记录包含了自更新世早期开始以来冰川和海洋条件的丰富信息。在NSF的结构中，已经确定了几个大型潜艇滑坡。快速的冰川沉积加上间冰期“弱”沉积层的形成通常被认为是冰川边缘如此大规模滑动背后的机制。然而，目前对此类滑动的触发和进展的理解仍然存在差距。Storegga滑坡（8.1kya）形成了最近的滑坡，在NSF东北部的现代海底可以看到。在埋藏的NSF层中还发现了另外三个：Tampen（0.15亿a）、more（0.4亿a）和Stad Slides（0.5亿a）。斯塔德滑坡形成最深，可能是最大的滑坡在NSF。直到最近，对这种深度（海底以下700-1000米）滑动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详细分析现在是可行的。因此，本研究旨在对NSF巨型滑坡进行详细分析，特别关注斯塔德滑坡。这包括形态学和沉积学分析，以揭示更多关于滑动驱动和进展的信息，以及这如何与冰盖行为联系起来，例如沉积物向TMFs输送的模式和速度。与其他滑梯的比较将揭示更多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。地震数据成像被埋的海底表面，不同沉积物类型之间的声学特征差异允许重建过去的沉积。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。该技术已被用于详细分析NSF和潜艇幻灯片，并且这些数据集的深度分辨率不断提高，现在使得Stad幻灯片可以进行类似的分析。研究问题1)从斯塔德滑坡的结构和形态可以推断出其驱动因素和机制？2)斯塔德滑坡与NSF上其他巨型潜艇滑坡有什么异同，这又揭示了它们的相关驱动因素和性质？3)关于欧亚冰盖第四纪的波动，这些幻灯片能揭示什么？”