Collaborative Research: Chronology of Ice Fluctuations in the South Shetland Islands Since the Last Glacial Maximum

该奖项支持对南半球气候变化时间的研究，目的是恢复从火地岛温带到极地南极半岛的关键纬度断面上以前的冰范围和波动以及古气候。已经在手的样本将允许对南设得兰群岛(SSI)的冰波动进行测年，SSI是横跨南极汇聚的一个关键位置。令人惊讶的是，关于该岛链中以前的冰层范围，几乎没有具体的证据。这项研究的结果将回答有关南极半岛冰层范围和随后冰川消融时间的一些基本问题。从乔治王和利文斯顿群岛上精心挑选的冰雹上收集的样本将产生一份宇宙暴露年龄年表。马里安湾外冰雹中的一块大型花岗闪长岩巨石的初步年龄为18000年，这表明冰雹可能代表了最后一次冰盛期(LGM)的冰位。这些数据表明，有可能在SSI中形成约20,000年的冰波动记录，这是以前从未实现的。这些数据不仅可以用来解决SSI中长期存在的关于LGM冰范围的争论，而且在评估大规模气候变化的全球同步性方面也将是有价值的。研究生和本科生都将参与其中。这项工作的基础是最近成功地使用铍-10(10Be)测定了南极早在300年前的冰川沉积物的年龄，以及2002/2003年在SSI绘制冰原地图和收集暴露年龄样本的意外机会。这项研究将对SSI中冰波动的时间、以前冰盖的范围和厚度产生新的理解，并可能使冰川年代学的发展从末次盛冰期延伸到全新世晚期。这项工作还将为气候变化的半球间比较提供基础，并符合极-赤道-极(PEP 1)样带的限制，以开发美洲和南极半岛高分辨率、年代准确的古气候记录。

This award supports a study of the timing of climate changes in the Southern Hemisphere with the goal of reconstructing former ice extent and fluctuations, as well as paleoclimate, along the key latitudinal transect from temperate Tierra del Fuego to the polar Antarctic Peninsula. Samples already in hand will allow the dating of ice fluctuations in the South Shetland Islands (SSI), a critical location where that transect crosses the Antarctic Convergence. Surprisingly little concrete evidence exists concerning former ice extent in the island chain. The results of this study will answer a number of basic questions regarding ice extent and the timing of subsequent deglaciation in the Antarctic Peninsula. A cosmogenic exposure-age chronology will be produced from samples collected at carefully selected moraines on King George and Livingston Islands. A preliminary age of 18,000 years for a large granodiorite boulder from the outer moraine at Marian Cove suggests that the moraine may represent the Last Glacial Maximum (LGM) ice position. These data point to the potential for developing a ~20,000-yr record of ice fluctuations in the SSI, something that has not been achieved previously. Such data could be used not only to settle the long-standing debate over LGM ice extent in the SSI, but also would be valuable in assessing the global synchrony of large climate changes. Both a graduate and undergraduate student will be involved. This work builds on the recent success in dating glacial deposits in the Antarctic as young as 300 years using Beryllium-10 (10Be), as well as on an unexpected opportunity to map moraines and collect exposure-age samples in the SSI in 2002/2003. This research will produce a new understanding of the timing of ice fluctuations in the SSI, the extent and thickness of former ice cover, and may allow the development of a glacial chronology extending from the LGM to the late Holocene. This work will also provide a basis for inter-hemispheric comparisons of climate change and fits within the constraints of the Pole-Equator-Pole (PEP 1) transect to develop high-resolution, well-dated paleoclimate records in the Americas and Antarctic Peninsula.