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

南极洲冰川的消融有可能导致全球海平面显著上升。全球定位系统（GPS）接收器测量到，南极半岛的陆地上升速度在加快，这是冰川消融加速的一个证据。然而，GPS对隆升的观测仅限于最近二十年。这项研究的一个目标是确定这些新观测到的隆起率如何与南极半岛在更长的时间间隔内的平均隆起率进行比较。研究人员将利用现在搁浅在南极半岛低洼海岸山丘上的古海滩的年龄和海拔高度来重建过去的海平面，以确定过去5000年的上升速度。研究人员还将利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如何记录在海滩沉积物中。这些新记录的好处将是三重的：(1)它们将有助于确定南极冰盖和相对海平面的自然变化；(2)它们将提供关于隆起和地球内部结构的新见解；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学校的推广活动中与圣巴巴拉自然历史博物馆的游客分享。本项目将资助三名研究生。技术描述古海平面数据对于重建过去冰盖的大小和范围，记录冰川退缩后增加的隆起，以及根据冰川后反弹的影响校正基于重力的冰质量损失测量是至关重要的。然而，与最近对北美冰盖复合体的研究中使用的500多个地点相比，只有14个地点有南极洲的相对海平面数据。这个项目的目的是利用光学刺激发光来确定南极半岛东部一系列新发现的凸起海滩的年代，以及南设得兰群岛一系列已知的凸起海滩的年代，但只是初步的年代。在凸起的海滩收集的数据包括年龄和海拔、探地雷达剖面、鹅卵石的圆度和浮冰碎片的岩性。该研究将验证三个假设：(1)与全新世晚期相比，南极半岛的隆升率在现代有所增加；(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)凸起海滩上的鹅卵石圆度和冰筏碎片的来源随时间系统地变化，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.