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

合作研究：自末次盛冰期以来南设得兰群岛冰涨落的年代学

• 批准号: 0338141
• 负责人: John Stone
• 金额: $ 8.39万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0338141&HistoricalAwards=false
• 关键词: Collaborative; Research; Chronology; Ice; Fluctuations

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.

该奖项支持对南半球气候变化时间的研究，目的是沿着从温带火地岛到极地南极半岛的关键纬度横断面重建以前的冰范围和波动以及古气候。 现有的样本将有助于确定南设得兰群岛（SSI）冰层波动的年代，南设得兰群岛是该横断面穿越南极辐合带的关键地点。令人惊讶的是，关于岛链以前冰层范围的具体证据很少。这项研究的结果将回答有关南极半岛冰层范围和随后冰消时间的一些基本问题。宇宙成因暴露年龄年表将从乔治王群岛和利文斯顿群岛精心挑选的冰碛中收集的样本产生。 玛丽安湾外冰碛中的一块大型花岗闪长岩的初步年龄为 18,000 年，表明该冰碛可能代表末次盛冰期 (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，这是以前从未实现过的。这些数据不仅可以用来解决关于SSI末次盛冰期冰范围的长期争论，而且对于评估全球气候变化的同步性也很有价值。研究生和本科生都将参与其中。这项工作建立在最近利用 Beryllium-10 (10Be) 测年南极冰川沉积物年龄长达 300 年的成功基础上，以及 2002/2003 年在 SSI 中绘制冰碛图并收集暴露年龄样本的意外机会的基础上。这项研究将对 SSI 中冰波动的时间、前冰盖的范围和厚度产生新的认识，并可能允许发展从末次盛冰期延伸到全新世晚期的冰川年代学。 这项工作还将为半球间气候变化比较提供基础，并适应极地-赤道-极地（PEP 1）横断面的限制，以开发美洲和南极半岛的高分辨率、日期明确的古气候记录。