Dating coseismic marine terrace formation during the Kaikoura 2016 earthquake

2016 年凯库拉地震期间同震海洋阶地形成的年代测定

• 批准号: NE/P021433/1
• 负责人: Martin Hurst
• 金额: $ 6.68万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP021433%2F1
• 关键词: Dating; coseismic; marine; terrace; formation

The recent earthquake in Kaikoura, New Zealand on 14th November 2016 resulted in the uplift of large stretches of coast. Previously intertidal rocky shore platforms cut into bedrock are now stranded high and dry above the tides. The opportunity to observe the marooning of raised marine terraces is rare, yet these are ubiquitous landforms flanking the coasts in tectonically active settings around the globe, from the edges of the Mediterranean Sea to the Pacific margin of the Andes and Rocky mountains. These marine terraces previously formed at sea level are important spatial and chronologic markers of the interactions between tectonic uplift and eustatic sea level change that allow reconstruction of a history of tectonic uplift rates. Terraces can be dated using cosmogenic isotopes (CIs), but the accuracy of ages is tied to inherent (and untested) assumptions about the nuclide inventory at the time of terrace abandonment. Moreover, their formation and abandonment are poorly understood because the processes involved are not typically observed in real time. The goal of this project is to address both of these existing knowledge gaps and use a shore platform instantaneously uplifted and abandoned during the 14th November 2016 Kaikoura, New Zealand earthquake to directly observe the processes of formation and abandonment of marine platforms. The Kaikoura earthquake demonstrated that the formation of stranded marine terraces can be due to instantaneous, coseismic uplift of previously active rocky shore platforms. We will measure 10Be concentrations from the surface of a newly stranded shore platform in a transect of in-situ bedrock samples so as to determine the apparent platform age at the time of terrace formation. We will also use measured 10Be concentrations in concert with existing data on shore platform and coastal erosion to understand the prior history of shore-platform development leading up to the earthquake in order to understand the inheritance of 10Be accumulated during active coastal development. The proposed work is vital for the provision of a baseline for future studies both locally and globally. Sampling must take place as soon as possible, prior to any significant breakdown of the surface due to subaerial weathering, deposition or human modification. This rare event provides a unique opportunity to calibrate and validate existing models for platform abandonment and evolution, and in turn improve our assessment of vertical tectonic rates and associated hazards in tectonically active coastal regions around the globe.

2016年11月14日在新西兰凯库拉发生的地震导致大片海岸隆起。以前的潮间带岩石海岸平台切割成基岩，现在搁浅在潮汐上方的高处和干燥处。观察海洋台地被放逐的机会是罕见的，但这些地貌在地球仪周围构造活跃的海岸两侧无处不在，从地中海边缘到安第斯山脉和落基山脉的太平洋边缘。这些先前在海平面形成的海洋阶地是构造抬升与海平面变化之间相互作用的重要空间和年代标记，可以重建构造抬升速率的历史。阶地可以使用宇宙成因同位素（CI）来定年，但年龄的准确性与阶地废弃时的核素库存的固有（和未经检验的）假设有关。此外，人们对它们的形成和废弃知之甚少，因为所涉及的过程通常不能在真实的时间内观察到。该项目的目标是解决这些现有的知识差距，并使用在2016年11月14日新西兰凯库拉地震期间瞬间升起和废弃的海岸平台，直接观察海洋平台的形成和废弃过程。凯库拉地震表明，搁浅的海洋阶地的形成可能是由于先前活跃的岩石海岸平台的瞬时同震抬升。我们将测量10 Be浓度从一个新搁浅的海岸平台在一个横断面的原位基岩样品，以确定在阶地形成时的表观平台年龄。我们还将使用测得的10 Be浓度与现有的海岸平台和海岸侵蚀数据相结合，以了解导致地震的海岸平台开发的历史，从而了解活跃的海岸开发过程中积累的10 Be的继承。拟议的工作对于为本地和全球的未来研究提供基线至关重要。取样必须在地表风化、沉积或人为改造造成任何重大破坏之前尽快进行。这一罕见的事件提供了一个独特的机会来校准和验证现有的平台废弃和演变模型，并反过来提高我们的垂直构造速率和相关的危害在构造活跃的沿海地区周围的地球仪的评估。