Grain size Characteristics and Evolution of Core Sedimentary Environment in the Houtao Plain Reach of the Yellow River

Key words: 
• grain size characteristic /
• sedimentary facies /
• Houtao plain /
• Yellow River

Abstract: Sediment grain size parameters provide important information about depositional processes and environments because the size range,mixing and sorting of sediment populations vary systematically in response to the sedimentation processes,dynamics and provenance. Thus the analysis of textural parameters is the basis for determining the process/response behavior of individual sedimentary units and their environment. Grain size distribution distinguishes the surface sedimentary environment in the Houtao plain,and was therefore adopted in this sedimentary facies interpretation of two drill cores from the Houtao plain reach of the Yellow River. The results show that the sedimentary environment underwent many transformations,dominated by fluvial channel facies(68% in Core DKZ04, and 57% in Core HDZ04). This indicates that the channel of the Yellow River has experienced extensive migration in this region. In addition,since aeolian sand appears only at the top of Core DKZ04,we speculate that the present desert landform of the northern Ulan Buh Desert started to form only 2 000 years ago,probably triggered by river migration and large-scale human activity.