Niveo‐aeolian deposits and denivation forms, with special reference to the great Kobuk Sand Dunes, Northwestern Alaska
Niveo‐aeolian deposits and denivation forms, with special reference to the great Kobuk Sand Dunes, Northwestern Alaska
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尼维奥-风成沉积物和衍生形式，特别是阿拉斯加西北部的科伯克沙丘
DOI：
10.1002/esp.3290130206
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发表时间：
1988
影响因子：
3.3
通讯作者：
J. Dijkmans
中科院分区：
文献类型：
--
作者：
E. Koster;J. Dijkmans
欧洲西北部广袤的晚更新世内陆和河流沙丘沙、风成沙(盖层沙)和冰缘黄土沉积的地貌、岩性和年代地层学是众所周知的。然而，其中一些风沙沉积是风沙作用的结果，这一观点仍然是一个悬而未决的问题，因为目前还没有关于诊断沉积特征的报道。此外，从不同寒冷气候地区报道的实际冰冻风沙沉积和相关的剥蚀形式，并不是合适的类似物。最近在阿拉斯加西北部活动沙丘地区的观察表明，风雪和沙子的层间作用优先发生在横向、沙丘状或抛物线状沙丘脊滑移面上。一年一度的断流形式出现：例如积雪堡垒、天坑、雪丘、积雪融化水扇和张性裂缝。表面由具有凹陷表面和海绵状结构的破裂的湿砂层组成。尽管在这种特殊情况下，这些特征的保存潜力很低，但在其他地方的古代沉积物中也可以观察到类似的特征，并提供有用的古气候指标。因此，尼韦-风沙的概念不应该像以前假设的那样，与欧洲西北部的晚更新世盖层沙沉积特别相关。
The geomorphology, lithology and chronostratigraphy of extensive, late Pleistocene inland and river dune sands, aeolian sand sheets (‘cover sands’) and loess deposits of periglacial origin in northwestern Europe are well known. However, the idea that some of these aeolian sediments result from niveo-aeolian processes is still an open question, as no diagnostic sedimentary features have yet been reported. Moreover, actual niveo-aeolian sediments and related denivation forms, reported from various cold-climate regions, are not suitable analogues. Recent observations in active dune fields in northwestern Alaska indicate that interstratification of wind-driven snow and sand preferentially occurs on slip faces of transverse, barchanoid or parabolic dune ridges. Annual denivation forms develop: e.g. snow ramparts, sinkholes, snow hummocks, snow meltwater fans and tensional cracks. The surface consists of a cracked wet sand layer with a dimpled surface and spongy structure. Although the preservation potential of these features is low in this specific case, similar features may be observed in ancient sediments elsewhere and provide useful palaeoclimatic indicators. The niveo-aeolian concept should therefore not specifically be related to late Pleistocene cover sand deposition in northwestern Europe, as previously assumed.