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首页> 外文期刊>Boreas >Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls
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Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls

机译：温带高寒山谷冰川每年冰formation形成的过程：对冰川动力学和气候控制的见解

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This paper presents the first detailed sedimentological study of annual moraines formed by an alpine valley glacier. The moraines have been forming since at least AD 1980 by a subsidiary lobe of Gornergletscher, Switzerland that advances up a reverse bedrock slope. They reach heights of 0.5–1.5 m, widths of up to 6 m and lengths of up to several hundreds of metres. Sediments in these moraines are composed of proglacial outwash and debris flow units; subglacial traction till is absent entirely. Based on four representative sections, three genetic process combinations have been identified: (i) inefficient bulldozing of a gently sloping ice margin transfers proglacial sediments onto the ice, causing differential ablation and dead-ice incorporation upon retreat; (ii) terrestrial ice-contact fans are formed by the dumping of englacial and supraglacial material from point sources such as englacial conduit fills; debris flows and associated fluvial sediments are stacked against a temporarily stationary margin at the start, and deformed during glacier advance in the remainder, of the accumulation season; (iii) a steep ice margin without supraglacial input leads to efficient bulldozing and deformation of pre-existing foreland sediments by wholesale folding. Ice-surface slope appears to be a key control on the type of process responsible for moraine formation in any given place and year. The second and third modes result in stable and higher moraines that have a higher preservation potential than those containing dead ice. Analysis of the spacing and climatic records at Gornergletscher reveals that winter temperature controls marginal retreat and hence moraine formation. However, any climatic signal is complicated by other factors, most notably the presence of a reverse bedrock slope, so that the extraction of a clear climatic signal is not straightforward. This study highlights the complexity of annual moraine formation in high-mountain environments and suggests avenues for further research.
机译：本文介绍了由高山峡谷冰川形成的年冰rain的首次详细沉积学研究。至少从1980年起，瑞士戈尔纳格彻彻（Gornergletscher）的一个副瓣就形成了冰rain。它们的高度为0.5–1.5 m，宽度最大为6 m，长度最大为几百米。这些冰rain的沉积物由冰川冲刷和泥石流单元组成。完全没有冰川下的牵引力。根据四个有代表性的部分，确定了三个遗传过程组合：（i）平缓倾斜的冰边缘的低效推土作用将冰川沉积物转移到冰上，在撤退时造成不同的消融和死冰掺入; （ii）地面冰接触风扇是通过倾倒来自点源（例如，冰层导管填充物）的冰层和冰层材料而形成的;泥石流和相关的河流沉积物在开始时堆积在临时静止的边缘，并在蓄积季节的剩余时间内在冰川前进期间变形。 （iii）没有超界面输入的陡峭冰缘导致有效的推土和通过批发折叠使先前存在的前陆沉积物变形。在任何给定的地点和年份，冰面坡度似乎是导致冰m形成过程类型的关键控制因素。第二种和第三种模式可产生稳定且更高的higher粒，与含有死冰的those粒相比，它们具有更高的保存潜力。对Gornergletscher的间隔和气候记录进行的分析表明，冬季温度控制着边际撤退，从而控制了冰ora的形成。但是，任何气候信号都会受其他因素的影响而复杂化，最明显的是存在反基岩坡度，因此提取清晰的气候信号并不容易。这项研究突出了高山环境中每年冰ora形成的复杂性，并提出了进一步研究的途径。

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