Robert D. McCulloch , Michael J. Bentley , Derek Fabel , Hans Fernández-Navarro , Juan-Luis García , Andrew S. Hein , Carla Huynh , Stewart S.R. Jamieson , María-Paz Lira , Christopher Lüthgens , Grace A. Nield , Manuel San Román , Eileen W. Tisdall
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We critically re-evaluate the extant evidence for the c. 15.0–12.0 cal ka BP lake, here named ‘Lago Kawésqar’, and provide further sedimentological and chronological evidence for its existence. We also provide new cosmogenic surface nuclide dating of erratic and bedrock samples collected from extensive field campaigns that confirm the rapid and widespread retreat of the Magellan ice fields to the inner fjords of the Fuegian archipelago by c. 16.0 ka. To resolve the apparent paradox between these two lines of evidence we propose that glacial isostatic adjustment led to a topographic barrier to lake drainage rather than an ice dam. We use Glacial Isostatic Adjustment modelling to demonstrate that rapid isostatic recovery following the early deglaciation after c. 17.0 cal ka BP likely led to elevation of the present shallow south-western coastal margin of the Fuegian archipelago. Final drainage of Lago Kawésqar was probably caused by neotectonic subsidence of the same margin along the boundary of the South American – Scotia tectonic plates at c. 12.0 cal ka BP.</div></div>","PeriodicalId":20926,"journal":{"name":"Quaternary Science Reviews","volume":"344 ","pages":"Article 108866"},"PeriodicalIF":3.2000,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53–54°S) during the last glacial – interglacial transition\",\"authors\":\"Robert D. McCulloch , Michael J. Bentley , Derek Fabel , Hans Fernández-Navarro , Juan-Luis García , Andrew S. Hein , Carla Huynh , Stewart S.R. Jamieson , María-Paz Lira , Christopher Lüthgens , Grace A. Nield , Manuel San Román , Eileen W. 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引用次数: 0
摘要
麦哲伦海峡(Estrecho de Magallanes)中部隆起的海岸线和相关的湖泊沉积物被解释为是在大约公元前 15.0 卡至 12.0 卡之间的晚冰期,心形冰川阻塞了一个大型冰期湖泊并阻止向南太平洋和南大洋排水的产物。然而,越来越多的冰川地质证据表明,麦哲伦冰盖的退缩时间更早,不足以在当时阻塞湖泊。我们对约公元前 15.0-12.0 卡卡湖(此处命名为 "Lago Kawésqar")的现存证据进行了严格的重新评估,并为其存在提供了进一步的沉积学和年代学证据。我们还提供了新的宇宙源表面核素测年方法,这些测年方法是在广泛的野外考察活动中采集的岩屑和基岩样本,证实了麦哲伦冰原在约 16.0 ka 年前向富给加群岛的内峡湾快速而广泛地后退。为了解决这两个证据之间的明显矛盾,我们提出冰川等静力调整导致了湖泊排水的地形障碍,而不是冰坝。我们利用冰川等静力调整模型来证明,大约公元前 17.0 千卡之后的早期冰川脱落之后的快速等静力恢复很可能导致了现在的富给加群岛西南浅海岸边缘的抬升。卡瓦斯卡尔湖(Lago Kawésqar)的最终排水很可能是由于大约公元前 12.0 卡卡年南美-斯科舍板块边界沿线同一边缘的新构造下沉造成的。
Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53–54°S) during the last glacial – interglacial transition
Raised shorelines and associated lacustrine sediments in the central Estrecho de Magallanes (Strait of Magellan) have been interpreted as products of cordilleran glaciers impounding a large proglacial lake and preventing drainage to the South Pacific and Southern Ocean during the Late glacial between c. 15.0 and 12.0 cal ka BP. However, a growing body of glacial geological evidence points towards an earlier retreat of the Magellan cordilleran ice dome, insufficient to dam lakes at that time. We critically re-evaluate the extant evidence for the c. 15.0–12.0 cal ka BP lake, here named ‘Lago Kawésqar’, and provide further sedimentological and chronological evidence for its existence. We also provide new cosmogenic surface nuclide dating of erratic and bedrock samples collected from extensive field campaigns that confirm the rapid and widespread retreat of the Magellan ice fields to the inner fjords of the Fuegian archipelago by c. 16.0 ka. To resolve the apparent paradox between these two lines of evidence we propose that glacial isostatic adjustment led to a topographic barrier to lake drainage rather than an ice dam. We use Glacial Isostatic Adjustment modelling to demonstrate that rapid isostatic recovery following the early deglaciation after c. 17.0 cal ka BP likely led to elevation of the present shallow south-western coastal margin of the Fuegian archipelago. Final drainage of Lago Kawésqar was probably caused by neotectonic subsidence of the same margin along the boundary of the South American – Scotia tectonic plates at c. 12.0 cal ka BP.
期刊介绍:
Quaternary Science Reviews caters for all aspects of Quaternary science, and includes, for example, geology, geomorphology, geography, archaeology, soil science, palaeobotany, palaeontology, palaeoclimatology and the full range of applicable dating methods. The dividing line between what constitutes the review paper and one which contains new original data is not easy to establish, so QSR also publishes papers with new data especially if these perform a review function. All the Quaternary sciences are changing rapidly and subject to re-evaluation as the pace of discovery quickens; thus the diverse but comprehensive role of Quaternary Science Reviews keeps readers abreast of the wider issues relating to new developments in the field.