The sediments of Lake L枚gurinn - A unique proxy record of Holocene glacial meltwater variability in eastern Iceland

详细信息	查看全文 | 推荐本文 |

• 作者：Johan Striberger^a ; ^{johan.striberger@geol.lu.se} ; Svante Bjö ; rck^a ; Sofia Holmgren^a ; Ladislav Hamerlí ; k^b ; ^c
• 关键词：Iceland ; Holocene ; Glacial meltwater variability ; Lake sediments ; Varves ; BSi ; Diatoms ; Chironomids
• 刊名：Quaternary Science Reviews
• 出版年：2012
• 期刊代码：78_02773791
• 类别：ear
• 出版时间：30 March, 2012
• 卷：38
• 期：Complete
• 页码：76-88
• 文件大小：1313 K

摘要

The full Holocene development of the large (8100聽km²) Vatnaj枚kull ice cap in Iceland with its many outlet glaciers is poorly known. The idea of an early deglaciation, leading to a glacier-free period in mid-Holocene, followed by the Neoglaciation is still the main concept for the glacial history in the North Atlantic region, including Iceland. We have examined a continuous sediment record from the glacier-fed Lake L枚gurinn in eastern Iceland to infer Holocene meltwater variability of Eyjabakkaj枚kull, which is a surge-type outlet glacier of the Vatnaj枚kull ice cap. We focus on the early and mid-Holocene, and our data show that Eyjabakkaj枚kull receded rapidly during the final phase of the last deglaciation, and did not deliver glacial meltwater to Lake L枚gurinn by 9000聽years BP, suggesting that Eyjabakkaj枚kull was significantly smaller than today at that time. The return of glacial meltwater transport to Lake L枚gurinn, and thus a return of Eyjabakkaj枚kull is dated to ca 4400聽years BP, suggesting an almost 5000 years long glacier-free period during early and mid-Holocene. During this time period, we infer that the 8.2 ka cold event did not cause a significant expansion of Eyjabakkaj枚kull, however, we note a marked decrease in the aquatic productivity in Lake L枚gurinn, which is suggested to be the result of shorter ice-free seasons of Lake L枚gurinn. The Holocene Thermal Maximum is inferred by a period of maximum Holocene aquatic productivity, and dated to ca 7900-7000聽years BP. Following the re-formation of Eyjabakkaj枚kull ca 4400聽years BP, we suggest that the glacier reached stable conditions ca 1700聽years BP, and remained fairly stable until the later part of the Little Ice Age, when Eyjabakkaj枚kull reached its maximum Holocene extent.