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

Abstract

The morphometric and petrographic characteristics of coarse-grained clasts (> 1 cm) sampled from 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 rock 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 are poorly rounded and characterized by a wide variety of shapes. More than 50 % of the studied clasts have a size of 1–2 cm, 25 % are 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 clasts from Siberian sources is less than 23 %. The distribution of coarse-grained clasts argues for the existence of quite a stable ice drift path in the past, which is similar to the modern Beaufort Gyre.