Tab. 2: Grain-sizes of cobble on the surface of sanderwurzel

yResults of 13 field investigations between 1966 and 1990 of the southwestern to eastern margin of Kötlujökull and its proglacial area are summarized with respect to sandar and their formation. Generally, the results are based on sedimentological examinations in the field and laboratory, on analyses of aerial photographs, and investigations of the glacier slope. The methods permitted a more detailed reconstruction of sandar evolution in the proglacial area of Kötlujökull since 1945, of tendencies in development and of single data going back until the last decades of the 19th century. Accordingly, there existed special periods of \"flachsander\"-formations with raised coarsegrained \"sanderwurzels\" resultant from the outbreak of subglacial meltwater tunneloutlets and other periods with \"hochsander-\"formations by supraglacial drainage. At present the belts of hochsanders in front of the glacier come up to more than 4 m in thickness and 1000 m in width, therefore containing perhaps more sediment direct in front of Kötlujökull than the old belts of flachsanderwurzels. In one case the explosion-like subglacial meltwater outburst combined with the genesis of a sanderwurzel could be observed for a time and is thoroughly discussed. The event is referred to the outburst of a sub- to inglacial meltwater body being under extreme hydrostatic press ures which is combined with the genesis of a new subglacial tunneloutlet as a new flachsander. Often these outbursts led to the destruction of a morainic belt more than 1000 m in width. Presumably the whole event was finished in not more than a few days. In addition to a characteristic pear-shaped form and water-moved stones up to diameters of 1 m the wurzels possess a single \"main-channel\" with rectangular cross-sections as far as 4 m deep and 50 m wide just as small flat channels resembling fish bones in connection with the main channel. Presumably, they have been active only in the last stage of wurzel formation. With regard to the subglacial tunnel gates long-living L-meltwater outlets are distinguished from short-living K-meltwater outlets. These are always combined with a raised coarse-grained sanderwurzel, but its meltwater discharge is generally decreasing and ceases after some years, whereas the discharge of L-meltwater outlets continues unchanged for long times (except seasonal differences). […]

本研究总结了1966年至1990年间针对克图卢约库尔冰川（Kötlujökull）西南至东缘及其冰前区域开展的13次野外调查成果，重点围绕冰川砂滩（sandar）及其形成过程展开。本次研究的基础数据主要来源于野外及室内沉积学检测、航空影像解译，以及冰川坡面调查工作。通过上述研究方法，我们得以更为细致地重建1945年以来克图卢约库尔冰前区域的冰川砂滩演化历程、发育趋势，以及可追溯至19世纪末的单组观测数据。据此可知，冰下融水隧道溃决引发粗粒“冰川砂滩根（sanderwurzels）”抬升，形成了特定的“薄型冰川砂滩（flachsander）”发育期；而冰面排水系统则造就了“厚型冰川砂滩（hochsander）”的发育阶段。当前，冰川前缘的厚型冰川砂滩带厚度可达4米以上，宽度达1000米，其赋存的沉积物总量或已超过古老的薄型砂滩根带。其中一次类似爆炸式的冰下融水溃决事件伴随砂滩根形成的过程被实时观测到，并得到了详尽讨论。该事件被归因于处于极端静水压力下的冰下/冰内融水体溃决，同时催生了新的冰下融水隧道出口，进而形成了新的薄型冰川砂滩。这类溃决事件往往会摧毁宽度超1000米的冰碛带，且整个过程通常仅需数日即可完成。除了标志性的梨形地貌与直径可达1米的水蚀砾石外，砂滩根还拥有深度可达4米、宽度达50米的矩形横截面“主槽”，以及与主槽相连的小型鱼骨状扁平支流槽。据推测，这类支流槽仅在砂滩根形成的最后阶段才会活动。针对冰下融水隧道出口，可分为长期运行的L型融水出口与短期运行的K型融水出口两类。二者均会伴随抬升的粗粒砂滩根形成，但K型出口的融水径流量通常会逐年衰减并最终停止，而L型出口的径流量则可长期保持稳定（季节性波动除外）。[…]