Morphostructural control in location of buried valleys and placers at the Upper Kolyma Upland

Abstract

Lower and Middle Pleistocene alluvial suites of the Upper Kolyma Upland valleys lie at small relative altitudes and are covered with Upper Pleistocene alluvium, the latter forming the terrasouvals surfaces. The same regularity is traced through the whole Upper Kolyma drainage basin which is located within an individual morphostructure of the Upper Kolyma Uplift rising during the Cenozoic. As structures of valleys and alluvium differ at different parts of the morphostructure, the morphostructural factor seems to be essential but does. Not fully control the valleys formation. The morphostructures influence valley profile form, relative altitude of alluvium of different age and subsequent distortion of ancient valleys floor. The terrace placers are mostly confined to local uplifts. Out of the limits of local morphostructures influence, the valley and alluvium structure is mainly controlled by complicate history of the valley evolution, typical for the region. As a result the ore bearing bodies are here not valley and terrace placers but buried placers.