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，其目标是沿着从温带火地岛到极地南极半岛的关键纬度样带重建以前的冰范围和波动，以及古气候。已经到手的样本将允许测定南设得兰群岛（SSI）的冰波动的年代，这是该样带穿过南极辐合带的关键位置。令人惊讶的是，几乎没有关于岛链上以前的冰范围的具体证据存在。这项研究的结果将回答一些关于南极半岛冰范围和随后冰消退时间的基本问题。从乔治国王岛和利文斯顿岛精心挑选的冰碛上收集的样本将产生宇宙形成暴露年龄年表。玛丽安湾外冰碛上的一块花岗闪长岩巨石的初步年龄为18000年，这表明该冰碛可能代表末次冰盛期（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，这是以前没有实现的。这些数据不仅可以用来解决长期以来关于SSI中LGM冰范围的争论，而且在评估大气候变化的全球同步性方面也很有价值。研究生和本科生都将参与。这项工作建立在最近利用铍-10 （10Be）测定南极冰川沉积物年龄的成功基础上，以及2002/2003年在SSI中绘制冰碛石和收集暴露年龄样本的意外机会。这项研究将对SSI冰波动的时间、前冰盖的范围和厚度产生新的认识，并可能允许从LGM延伸到晚全新世的冰川年代学的发展。这项工作还将为半球间气候变化的比较提供基础，并在极-赤道-极（PEP 1）样带的约束下进行拟合，从而在美洲和南极半岛建立高分辨率、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.