Scanning electron microscopy of Pleistocene sands from Yamal and Taz peninsulas, Ob River Estuary, northwestern Siberia

Coastal sediments in the Ob River Estuary of northwestern Siberia are considered to have either glacial and/or estuarine/alluvial origins. One school of thought argues for interconnected ice domes on the continental shelf that linked the Fenno-Scandinavian and Siberian ice (Grosswald Thesis). Another school of thought argues for an estuarine/alluvial origin (Danilov-Vtyermin thesis). The key to solving the problem of the origin of these sediments lies in detailed stratigraphic, oxygen-18 and scanning electron microscopic (SEM) analysis of sediments. Both the stratigraphy and SEM results support the hypothesis of very limited Pleistocene glacial activity on Yamal, Gydan and Taz peninsulas. The SEM analysis points to a vast majority of rounded quartz grains, with V-shaped percussion microfractures, and a great range of preweathered microtextures. The SEM microtextures support a fluvial origin for the sediments far removed from any glacial source. A companion paper in this volume by Fred Michel discusses the O-18 analysis of ground ice in the area. (C) 1997 INQUA/Elsevier Science Ltd.