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Does glacial environment produce glacial mineral grains? Pro- and supra-glacial Icelandic sediments in microtextural study
Quaternary International ( IF 1.9 ) Pub Date : 2021-03-24 , DOI: 10.1016/j.quaint.2021.03.029
Edyta Kalińska , Kristaps Lamsters , Jānis Karušs , Māris Krievāns , Agnis Rečs , Jurijs Ješkins

Mineral grains from proglacial and supraglacial sedimentary settings in central south-eastern Iceland are considered in this study and analysed with the use of scanning electron microscope (SEM) techniques. By applying this, it is attempted to answer the key research question of whether quartz grains that come from a glacial-related sedimentary environment are indeed of glacial origin. The study also attempts to provide a linkage between microtextures produced on coarser and finer grains and to verify whether mineral grains from adjacent cryconite holes are similar or different. The preliminary assumption was that the more intense glacial grain record was based on several glacial activities from more and less recent glacial events in Iceland, and this assumption is true to some extent, because a set of sustained-shear-stress microtextures is found on coarser grains, especially in supraglacial and terminal moraine sediment samples. This latter reveals as much as 9% of glacial-type microtextures and this value seems much lower than in previous studies, which clearly argues for only limited grain glacial transformation. Glacial grains diminish with distance from a glacier, where fluvial grains dominate. Fine-grained cryoconite mineral grains reveal a proportion of glacially-induced microtextures that, nonetheless, may be a result of grain-crushing in the finer fraction. Long-distance-transported grains are practically absent in the finer fraction, likely because they are still too large to be entrained into the atmosphere. Finally, the adjacent neighbouring cryoconite holes reveal a different set of grain types, meaning that every cryoconite hole is independent and its grain type might be very random.



中文翻译:

冰川环境会产生冰川矿物颗粒吗?冰川前和冰川上的沉积物微观结构研究

在这项研究中考虑了冰岛东南部中部冰川和沉积上沉积环境中的矿物颗粒,并使用扫描电子显微镜(SEM)技术进行了分析。通过应用这种方法,试图回答一个关键的研究问题,即来自与冰川有关的沉积环境的石英颗粒是否确实是冰川起源的。这项研究还试图提供在较粗和较细晶粒上产生的微观纹理之间的联系,并验证来自相邻冰晶岩孔的矿物晶粒是否相似或不同。最初的假设是,更强烈的冰川谷物记录是基于来自冰岛越来越少的冰川事件的几次冰川活动而得出的,这种假设在一定程度上是正确的,因为在较粗的晶粒上发现了一组持续的剪切应力微观纹理,特别是在冰河相和终端冰ora沉积物样品中。后者揭示了多达9%的冰川类型的微纹理,并且该值似乎比以前的研究低得多,后者显然仅主张有限的冰川变化。冰川颗粒随着与冰川的距离的减小而减少,而冰川颗粒占主导地位。细粒的冰晶岩矿物晶粒显示出一定程度的冰川引起的微纹理,尽管如此,这可能是由于细颗粒中的颗粒破碎所致。实际上,远距离运输的谷物中没有这么细的颗粒,这可能是因为它们仍然太大而无法夹带到大气中。最后,相邻的邻近冰晶孔显示出一组不同的晶粒类型,

更新日期:2021-03-24
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