Grain-size composition and depositional environment of surface sediments in the Kubuqi Desert, China

Abstract

Sediments are the material basis for the development of eolian landscapes, and dune sediments contain key information about dune formation and development. The surface sediments of parabolic dunes, crescent dunes and chains, reticulate dune chains, compound dunes, ridge–honeycomb dunes, shrub-coppice dunes, and inter-dune lowlands in the Kubuqi Desert were studied. The grain-size parameters of dune sediments were measured, and their geographical patterns assessed. In the Kubuqi Desert, parabolic dunes contain the coarsest sediment and shrub-coppice dunes the finest. The average grain size of the overall surface sediment is 2.14–2.73 φ, with poor sorting, which is in the middle of the grain-size range compared with other deserts globally. The depositional environment of the Kubuqi Desert is dominated by eolian and flood deposition; the Yellow River, inland rivers, and seasonal alluvial-flood channels alter the dynamic conditions of the desert depositional environment. The major proximal material sources of surface sediments in the Kubuqi Desert are fluvial sediments remaining after Yellow River channel oscillation, fluvial alluvium and sediments in the Yellow River valley, remnant-slope deposits weathered from mountain bedrock, and stream-phase alluvial deposits in dry denuded uplands. The crescent dunes and chains and the compound dunes have a common sediment source.