Dating coseismic marine terrace formation during the Kaikoura 2016 earthquake

最近于2016年11月14日在新西兰凯库拉发生的地震导致大片海岸抬升。以前的潮间带岩石海岸平台切入基岩，现在在潮汐之上搁浅，高度和干燥。观察凸起的海洋梯田漂流的机会很少，但这些都是无处不在的地貌，位于全球构造活跃的海岸两侧，从地中海边缘到安第斯山脉和落基山脉的太平洋边缘。这些以前在海平面上形成的海洋阶地是构造抬升和海平面变化之间相互作用的重要空间和时间标志，可以重建构造抬升速率的历史。可以使用宇宙成因同位素(Cis)来确定梯田的年代，但年龄的准确性取决于关于梯田废弃时核素清单的固有(和未经检验的)假设。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是实时观察的。该项目的目标是解决这两个现有的知识差距，并利用2016年11月14日新西兰凯库拉地震期间瞬间抬升和废弃的岸上平台，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以归因于先前活跃的岩石海岸平台的瞬时同震抬升。我们将测量一个新搁浅的海岸平台表面的原位基岩样品的10Be浓度，以确定阶地形成时的视平台年龄。我们还将利用测得的10Be浓度结合现有的岸台和海岸侵蚀数据来了解地震前岸台发育的历史，以了解在海岸活跃发展过程中积累的10Be的继承性。拟议的工作对于为今后的本地和全球研究提供基线至关重要。取样必须尽快进行，在地表因空气风化、沉积或人为修改而发生重大破坏之前。这一罕见的事件提供了一个独特的机会，可以校准和验证现有的平台废弃和演化模型，进而改进我们对全球构造活跃的沿海地区垂直构造速率和相关灾害的评估。

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.