Long term records and impacts of glacially-fed river systems in Patagonia

巴塔哥尼亚冰川河流系统的长期记录和影响

• 批准号: 2112922
• 金额: --
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2112922
• 关键词: Long; term; records; impacts; glacially

This research focuses on the long-term changes in fluvial geomorphology and sediment dynamics at the Rio Chubut (Argentina). The aim is to develop a geomorphological history and test the environmental drivers responsible for the temporal changes in geomorphic development. Quaternary scientists study the past behaviour of the Patagonian ice sheet to aid understanding and projections of the environmental impact of contemporary climate change (Darvill et al, 2017; Boex et al, 2013; Glasser et al, 2008). Expansion and recession of the ice sheet and its glaciers cause geomorphic change in the environmental systems that it is coupled to. This includes proglacial lakes which have been studied for their high resolution varve records (Bendle et al, 2017). However, the extensive network of river systems that drain the ice sheet melt water depending on the extent of the ice, are understudied in the region despite being highly sensitive to ice dynamics and environmental change.Research methods for this study begin with the mapping of geomorphology using remotely sensed data e.g. aerial imagery of the Rio Chubut to identify geomorphic units that indicate past environmental conditions. Small scale metric data such as channel width and meander wavelength has been collected from abandoned river channels to infer historic water supply and energy levels in the system. Fieldwork has been completed in Oct/Nov 2019 where geophysical survey, sediment description and sampling for luminescence dating was carried out to collect more data on channel characteristic, sediment supply and to constrain a chronology of change respectively. The data collected in the field will ultimately inform a luminescence-based landform chronology (to be completed in year 2) and hydrogeomorphological modelling (to be completed in year 3) which can test hypotheses on the magnitude, frequency and time scale of fluvial change.Fluvial change in this region has wider significance given the deglacial decoupling from ice masses and the interaction with the Southern Westerlies, and other hydroclimate parameters e.g. El Nñio Southern Oscillation (ENSO), the loss of glacial waters from fluvial systems is a growing concern in Patagonia forming a key water supply sources. Characterising the dynamics and long term evolution of past fluvial systems through glacial, deglacial and postglacial times forms a valuable analogue for understanding future changes,In summary, this project will develop insight into the way rivers formerly fed by glacial outwash have responded to climate shifts during and after the major glacial episodes of the late Quaternary.ReferencesBendle, J.M., Palmer, A.P., Thorndycraft, V.R. and Matthews, I.P., 2017. High-resolution chronology for deglaciation of the Patagonian Ice Sheet at Lago Buenos Aires (46.5 S) revealed through varve chronology and Bayesian age modelling. Quaternary Science Reviews, 177, pp.314-339.Boex, J., Fogwill, C., Harrison, S., Glasser, N.F., Hein, A., Schnabel, C. and Xu, S., 2013. Rapid thinning of the late Pleistocene Patagonian Ice Sheet followed migration of the Southern Westerlies. Scientific reports, 3, p.2118.Darvill, C.M., Stokes, C.R., Bentley, M.J., Evans, D.J. and Lovell, H., 2017. Dynamics of former ice lobes of the southernmost Patagonian Ice Sheet based on a glacial landsystems approach. Journal of Quaternary Science, 32(6), pp.857-876.Glasser, N.F., Jansson, K.N., Harrison, S. and Kleman, J., 2008. The glacial geomorphology and Pleistocene history of South America between 38 S and 56 S. Quaternary Science Reviews, 27(3-4), pp.365-390.

这项研究的重点是里奥丘布特河（阿根廷）河流地貌和沉积物动态的长期变化。目的是发展地貌历史并测试导致地貌发展时间变化的环境驱动因素。第四纪科学家研究巴塔哥尼亚冰盖过去的行为，以帮助理解和预测当代气候变化对环境的影响（Darvill 等，2017；Boex 等，2013；Glasser 等，2008）。冰盖及其冰川的扩张和衰退会导致与其耦合的环境系统发生地貌变化。这包括已对其高分辨率 varve 记录进行研究的前冰川湖泊（Bendle 等人，2017 年）。然而，尽管该地区对冰动态和环境变化高度敏感，但根据冰的范围排出冰盖融水的广泛河流系统网络尚未得到充分研究。里约丘布特河的航空图像，用于识别表明过去环境条件的地貌单元。从废弃的河道中收集了小规模的度量数据，例如河道宽度和曲流波长，以推断系统中的历史供水和能源水平。实地工作已于 2019 年 10 月/11 月完成，进行了地球物理调查、沉积物描述和发光测年采样，以收集更多有关河道特征、沉积物供应的数据并分别限制变化的年代。现场收集的数据最终将为基于发光的地貌年代学（将在第 2 年完成）和水文地貌建模（将在第 3 年完成）提供信息，这些模型可以测试有关河流变化的幅度、频率和时间尺度的假设。考虑到冰消与冰块的脱钩以及与南西风带和其他水文气候的相互作用，该地区的河流变化具有更广泛的意义 参数例如厄尔尼奥南方涛动 (ENSO) 导致河流系统冰川水流失，成为巴塔哥尼亚关键供水源日益受到关注的问题。描述过去河流系统在冰期、冰消期和冰后时期的动态和长期演化特征，为理解未来的变化提供了一个有价值的类比。总之，该项目将深入了解以前由冰川冲刷补给的河流在第四纪晚期主要冰川期期间和之后对气候变化的反应方式。 虚拟现实和 Matthews, I.P.，2017。通过 varve 年代学和贝叶斯年龄模型揭示了布宜诺斯艾利斯湖 (46.5 S) 巴塔哥尼亚冰盖冰川消融的高分辨率年代学。第四纪科学评论，177，第 314-339 页。Boex, J.、Fogwill, C.、Harrison, S.、Glasser, N.F.、Hein, A.、Schnabel, C. 和 Xu, S.，2013。随着南西风带的迁移，晚更新世巴塔哥尼亚冰盖迅速变薄。科学报告，3，第 2118 页。Darvill, C.M.、Stokes, C.R.、Bentley, M.J.、Evans, D.J.和Lovell, H.，2017。基于冰川土地系统方法的最南端巴塔哥尼亚冰盖前冰瓣的动力学。 《第四纪科学杂志》，32(6)，第 857-876 页。Glasser, N.F.、Jansson, K.N.、Harrison, S. 和 Kleman, J.，2008。南美洲 38 S 和 56 S 之间的冰川地貌和更新世历史。第四纪科学评论，27(3-4)，第 365-390 页。