Abstract The expansion of ice sheets over soft, sandy substrates was widespread in the Early Palaeozoic, during the Late Ordovician glaciation of North Africa and Arabia. Similarly, large parts of southern Africa were glaciated by soft bedded ice sheets in the Late Palaeozoic Ice Age. An unanswered question is the extent to which subglacial deformation involved the passive recycling of unconsolidated materials, or the active production of new sediment through erosion and shearing. Here, we compile thin section data dovetailed with scanning electron microscope imagery from sandy subglacial substrates from South Africa, Algeria and Libya. Six samples were collected from soft-sediment striated pavements, i.e., surfaces that were sheared and deformed subglacially in an unconsolidated state. The samples show a considerable variation in deformation style but a unifying trait is the occurrence of striated and facetted quartz sand grains. These textural features testify to grain-grain attrition, and the potential production of sediment in the subglacial environment.

中文翻译：

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软层古生代冰盖下沉积物变形与产生

摘要 早古生代，北非和阿拉伯的晚奥陶世冰川期间，冰盖在柔软的沙质基质上的扩张普遍存在。同样，在晚古生代冰河时代，南部非洲的大部分地区都被软层冰盖冰川覆盖。一个悬而未决的问题是，冰下变形在多大程度上涉及松散材料的被动回收，或通过侵蚀和剪切主动产生新的沉积物。在这里，我们汇编了薄片数据，并与来自南非、阿尔及利亚和利比亚的沙质冰下基底的扫描电子显微镜图像相吻合。从软沉积物条纹路面收集了六个样品，即在未固结状态下在冰下剪切和变形的表面。样品显示出相当大的变形方式变化，但一致的特征是出现条纹和刻面石英砂颗粒。这些纹理特征证明了颗粒磨损以及冰下环境中沉积物的潜在产生。