Origin of the coarse-grained (> 1 cm) clasts from the Mendeleev Ridge area (Central Arctic Ocean)

Abstract

The morphometric and petrographic characteristics of the coarse-grained clasts (> 1 cm) sampled from the sediments of the Amerasian Basin, Central Arctic Ocean, were studied. Most of the clasts are represented by dolomites (46,4%), sandstones (22,8%) and limestones (19,8%); the amount of other rocks fragments (chert, shale, igneous) is about 10%. A variety of lithological types were identified among the studied rock fragments. Limestones and dolomitic limestones often contain fragments of fauna. The majority of clasts is poorly rounded and characterized by a wide variety of shapes. More than half of the studied clasts have a size of 1-2 cm, a quarter - 2-3 cm, and larger clasts only occur in insignificant amounts. Geophysical surveys across the sampling sites showed a lack of bedrock outcrops, so the studied coarse-grained clasts are not of local origin. It is concluded that they were predominantly delivered from the Canadian Arctic Archipelago (likely from the platform area, e.g., Victoria Island), mainly due to iceberg rafting during deglaciation periods. The maximum possible contribution of the clasts from the Siberian sources is less than 23%. Distribution of the coarse-grained clasts argues for the existence of a quite stable ice drift path in the past, which is similar to the modern Beaufort Gyre.