Paraglacial landscapes in St George's Bay, Newfoundland, Canada
Paraglacial landscapes in St George's Bay, Newfoundland, Canada
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加拿大纽芬兰圣乔治湾的冰川景观
DOI：
10.1144/m46.55
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
J. Shaw
中科院分区：
文献类型：
--
作者：
J. Shaw
纽芬兰圣乔治湾的威斯康星州晚期海底冰碛在全新世早期相对海平面-25 m低位期间和之后遭受了侵蚀过程。主要形态已被很大程度上去除，形成了一个缓坡平台，上面覆盖着流动的沙子和砾石，终止于渐进的“溢出”裂片的向陆一侧。沿海第四纪沉积物的侵蚀产生了以砾石为主的沙嘴系统和在水下平台上建造的屏障，这些平台埋藏了冰川沉积物和低位三角洲。因此，冰川作用形成了复杂的海底地形，在加拿大大西洋地区很少有类似的地形。
一个平缓倾斜的平台状浅滩（平均深度 20 m）横跨圣乔治湾内部（图 1a），向东包围了几个盆地（最大深度 100 m）。平台表面包括沙波、砾石波纹区域和固定的巨石砾石斑块，起伏为 2-3 m（例如图 1a 中的 A）。这种马赛克地形反映在反向散射图像中（图 1b）。由于波浪作用，沙子和砾石迁移到东北部，溢出到邻近的盆地，形成叶状、进积的沉积楔（例如……中的 B）。
The Late Wisconsinan submarine moraine in St George's Bay, Newfoundland, was exposed to erosional processes during and after an early Holocene −25 m lowstand of relative sea level. Primary morphology has been largely removed, resulting in a gently sloping platform veneered with mobile sand and gravel, terminating on the landward side in progradational ‘spillover’ lobes. Erosion of coastal Quaternary deposits has produced systems of gravel-dominated spits and barriers constructed upon subaqueous platforms that have buried glacimarine deposits and a lowstand delta. Paraglacial processes have therefore created a complex submarine terrain with few parallels in Atlantic Canada.
A gently sloping platform-like shoal (average depth 20 m) extends across inner St George's Bay (Fig. 1a), enclosing several basins to the east (maximum depth 100 m). The platform surface comprises sand waves, areas of gravel ripples and patches of immobile, bouldery gravel with relief of 2–3 m (e.g. A in Fig. 1a). This mosaic of terrains is reflected in a backscatter image (Fig. 1b). As a result of wave action, sand and gravel have migrated to the NE, spilling into the adjacent basins to form lobate, prograding sediment wedges (e.g. B in …