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首页> 外文期刊>Journal of Paleolimnology >Recent occurrence of large jökulhlaups at Lake Tuborg, Ellesmere Island, Nunavut
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Recent occurrence of large jökulhlaups at Lake Tuborg, Ellesmere Island, Nunavut

机译：努纳武特州Ellesmere岛的Tuborg湖最近出现大型jökulhlaups

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The varved sediment record from glacially-fed Lake Tuborg, Ellesmere Island, Nunavut, shows that only three large jökulhlaups have occurred there in the last millennium: 2003, 1993, and 1960. Detailed analyses of sediment microstructure and particle size, combined with in-situ hydrometeorological and limnological process studies, allowed jökulhlaup facies identification and discrimination from deposits from other processes. Deposits from large jökulhlaups are anomalously thick, typically lack internal structure, have sharp bases, and fine upwards. The ice-dammed lake above Lake Tuborg (the source of the jökulhlaups) likely changed its drainage style in 1960, from ice-dam overtopping to ice-dam flotation and glacial tunnel enlargement by melt widening, which allowed the lake to drain completely and catastrophically. Complete drainage of ice-dammed lakes by ice-dam flotation is rare in the region is due to the pervasiveness of cold-based ice. Twentieth century warming is likely responsible for some combination of dam thinning, lake expansion and deepening, and changing the thermal regime at the base of the dam. Anomalously thick individual varves were periodically deposited beginning in the nineteenth century, and their thickness increased with time. This likely reflects a combination of increased ice dam overtopping, subaqueous slope failures, sediment availability and rising air temperature. The varve record presented here significantly correlates with a previous, shorter record from Lake Tuborg. However, generally weak correlations are found between the new varve time series, regional records of air temperature, and glacial melt from ice cores on the Agassiz Ice Cap. It is hypothesized that on short timescales, sedimentation at the coring location reflects a complex and varying integration of multiple hydroclimatic, geomorphic and limnologic influences.
机译：来自努纳武特州埃勒斯米尔岛埃勒斯米尔岛的冰川喂养的图博格湖的沉积沉积记录表明，在最近的一个千年中，仅在2003年，1993年和1960年发生了3次大型jökulhlaups沉积物的详细分析。原位水文气象和林学过程研究使jökulhlaup的相得以识别和与其他过程的沉积物区分开。大型jökulhlaups的沉积物异常厚，通常缺乏内部结构，具有锋利的底部，向上细密。图博格湖（jökulhlaups的发源地）上方被冰堵的湖泊可能在1960年改变了排水方式，从冰坝的顶峰到冰坝的浮选和融化加宽的冰川隧道扩大，这使得该湖的排水彻底而灾难性。由于冷基冰无处不在，通过冰坝浮选将冰坝湖泊完全排干的情况在该地区很少见。二十世纪的变暖可能是水坝变薄，湖泊扩张和加深以及改变水坝底部热力状况的某种组合。从十九世纪开始，异常厚的单个瓣膜定期沉积，并且其厚度随时间增加。这很可能反映了冰坝超载，水下斜坡失稳，沉积物可利用性和气温上升的综合作用。这里显示的varve记录与Tuborg湖先前的较短记录显着相关。但是，通常在新的脉动时间序列，区域气温记录和阿加西冰川顶上的冰芯融化的冰川之间发现弱的相关性。假设在较短的时间尺度上，取芯位置的沉积反映了多种水气候，地貌和岩性影响的复杂变化。

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