Collaborative Research: New Constraints on Post-Glacial Rebound and Holocene Environmental History along the Northern Antarctic Peninsula from Raised Beaches

非技术描述南极冰川融化有可能导致全球海平面显著上升。根据GPS接收器的测量，冰川加速融化的一个证据是南极半岛的陆地上升速度加快。然而，GPS对隆起的观测仅限于过去20年。这项研究的一个目标是确定这些新观测到的隆升速率如何与南极半岛较长时间间隔内的平均隆升速率进行比较。研究人员将利用南极半岛低洼沿海丘陵上搁浅的古代海滩的年龄和海拔来重建过去的海平面，以确定过去5000年的抬升速度。研究人员还将使用探地雷达分析海滩的结构和海滩沉积物的特征，以了解海平面上升和过去的气候变化是如何记录在海滩沉积物中的。这些新记录的好处有三：(1)它们将有助于确定南极冰盖和相对海平面的自然变异性；(2)它们将提供关于隆起和地球内部结构的新见解；以及3)它们将帮助研究人员改进用于确定地质沉积物年龄的方法。研究结果将在K-12学校的推广活动中分享，并与圣巴巴拉自然历史博物馆的参观者分享。三名研究生将通过这个项目得到支持。技术说明古海平面数据对于重建过去冰盖的大小和范围、记录冰川消退后的抬升增加以及根据冰川后反弹的影响校正基于重力的冰块损失测量至关重要。然而，只有14个地点有南极洲的相对海平面数据，而最近一项对北美冰盖复合体的研究使用了500多个地点。该项目的目的是利用光学激发发光来确定南极半岛东部新发现的一系列隆起海滩的年代，以及南设得兰群岛一系列已知但仅初步确定年代的隆起海滩的年代。将在抬高的海滩收集的数据包括年龄和海拔、探地雷达剖面、鹅卵石的圆度和冰筏碎片的岩性。这项研究将检验三个假设：(1)相对于南极半岛的晚全新世，现代的抬升速率有所增加；(2)南极半岛北端的海平面历史与南设得兰群岛的海平面历史明显不同；(3)凸起的海滩上的鹅卵石圆度和冰筏碎片的来源随着时间的推移而系统地变化，反映了南极半岛北部的气候历史。

Nontechnical DescriptionGlacier ice loss from Antarctica has the potential to lead to a significant rise in global sea level. One line of evidence for accelerated glacier ice loss has been an increase in the rate at which the land has been rising across the Antarctic Peninsula as measured by GPS receivers. However, GPS observations of uplift are limited to the last two decades. One goal of this study is to determine how these newly observed rates of uplift compare to average rates of uplift across the Antarctic Peninsula over a longer time interval. Researchers will reconstruct past sea levels using the age and elevation of ancient beaches now stranded above sea level on the low-lying coastal hills of the Antarctica Peninsula to determine the rate of uplift over the last 5,000 years. The researchers will also analyze the structure of the beaches using ground-penetrating radar and the characteristics of beach sediments to understand how sea-level rise and past climate changes are recorded in beach deposits. The benefits of these new records will be threefold: (1) they will help determine the natural variability of the Antarctic Ice Sheet and relative sea level (2) they will provide new insight about uplift and the structure of the Earth's interior; and 3) they will help researchers refine the methods used to determine the age of geologic deposits. The study results will be shared in outreach events at K-12 schools and with visitors of the Santa Barbara Natural History Museum. Three graduate students will be supported through this project. Technical descriptionPaleo sea-level data is critical for reconstructing the size and extent of past ice sheets, documenting increased uplift following glacial retreat, and correcting gravity-based measurements of ice-mass loss for the impacts of post-glacial rebound. However, there are only 14 sites with relative sea-level data for Antarctica compared to over 500 sites used in a recent study of the North American Ice-Sheet complex. The purpose of this project is to use optically stimulated luminescence to date a series of newly discovered raised beaches along the eastern Antarctic Peninsula and an already known, but only preliminarily dated, series of raised beaches in the South Shetland Islands. Data to be collected at the raised beaches include the age and elevation, ground-penetrating radar profiles, and the roundness of cobbles and the lithology of ice-rafted debris. The study will test three hypotheses: (1) uplift rates have increased in modern times relative to the late Holocene across the Antarctic Peninsula, (2) the sea-level history at the northern tip of the Antarctic Peninsula is distinctly different than that of the South Shetland Islands, and (3) cobble roundness and the source of ice-rafted debris on raised beaches varied systematically through time reflecting the climate history of the northern Antarctic Peninsula.