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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Quantifying glacial erosion on a limestone bed and the relevance for landscape development in the Alps
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Quantifying glacial erosion on a limestone bed and the relevance for landscape development in the Alps

机译：量化石灰岩床上的冰川侵蚀以及阿尔卑斯山区景观发展的相关性

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摘要

Glacial erosion is the basic process that has shaped the landscapes of the Alps. Despite intense research over centuries, and the use of various techniques, determination of glacial erosion rates remains challenging. This is not only because the location where the process occurs is almost inaccessible, but also because it is dependent on many different factors, including ice thickness and velocity, glacier thermal regime and lithology. Reported glacial erosion rates range over several orders of magnitude (0.01 to >10 mm a(-1)). Most studies focus on crystalline bedrock, whereas few researchers have investigated glacial erosion on limestone. Here we analyse glacially polished bedrock surfaces at the recently deglaciated forefield of the Tsanfleuron glacier, Swiss Alps. The nearly horizontally bedded limestone hosts a well-developed karst system. Meltwater from the glacier drains into the subsurface within a few metres of the ice margin. By combining geomorphological mapping, measurement of cosmogenic Cl-36 concentrations of glacially eroded bedrock surfaces and a numerical model (MECED), we quantify at each sample location the amount of rock removed during glacier occupation. The glacial erosion rates calculated from these values range from 0 to 0.08 mm a(-1). These are orders of magnitude lower than values measured at comparable sites on crystalline bedrock. The high Cl-36 concentrations we measured show that the Tsanfleuron glacier was unable to effectively erode the gently dipping, strongly karstified limestone. We suggest that this effect may play a key role in formation and preservation over many glacial cycles of high-elevation, low-relief limestone plateaus in the Alps. (c) 2020 John Wiley & Sons Ltd.
机译：冰川侵蚀是形成阿尔卑斯山的景观的基本过程。尽管研究了几个世纪以来，但使用各种技术，但冰川侵蚀率的测定仍然具有挑战性。这不仅是因为进程发生的位置几乎无法进入，而且因为它取决于许多不同的因素，包括冰厚度和速度，冰川热力制度和岩性。报告的冰川侵蚀率范围在几个数量级（0.01至> 10mm A（-1））上。大多数研究专注于晶体基岩，而少数研究人员在石灰石上调查了冰川侵蚀。在这里，我们分析了最近被解放的Tsanfleuron Glacier，瑞士阿尔卑斯山的玻璃抛光的基岩表面。几乎水平的卧式石灰石举办了一个发达的岩溶系统。从冰川的熔融水流入冰距的几米范围内的地下。通过组合地貌测绘，测量冰川侵蚀的基岩表面的富含CL-36浓度和数值模型（MECED），我们在每个样品位置量化冰川占用期间拆除的岩石量。从这些值计算的冰川侵蚀率范围为0至0.08mm A（-1）。这些是比结晶基岩上的可比点测量的值低的数量级。我们测量的高CL-36浓度表明，Tsanfleuron冰川无法有效地侵蚀轻微的浸渍，强烈的令人作呕的石灰石。我们建议这种效果可能在山上的许多冰川周期，在阿尔卑斯山的冰川周期中的形成和保存中发挥关键作用。 （c）2020 John Wiley＆Sons Ltd.

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