Comparison and significance of grain size parameters of the Menyuan loess calculated using different methods

Abstract

Grain size is a fundamental physical property of sediments, and its parameters are crucial indicators of the provenance, transport processes, and depositional environments. However, owing to the availability of graphic and moment method choices for the determination of grain size parameters, the associated data are characterized by inconsistencies, and these issues restrict the utilization of such data. Compared to other regions, comparative analyses of grain size parameters determined using the graphic and moment methods for aeolian sediments in the Tibetan Plateau are scant. To obtain more accurate information and optimize and integrate historical data, in the present study, sediments in the Yahecun section of the Menyuan Basin in the northeastern Tibetan Plateau were investigated. Data for the Menyuan loess show that the mean grain size, sorting, skewness, and kurtosis data obtained from the two methods can be converted using linear equations. However, differences in the descriptions following the establishment of relationships should be considered. Owing to its sedimentary characteristics, the moment method is more suitable for determining grain size parameters for the Menyuan loess. The results from the moment method indicate that the Menyuan loess originated from multiple sources involving varying dynamics, and the sediments recorded changes from a cold, dry to a warm climate.

Keywords

• grain size parameters
• moment method
• graphic method
• aeolian loess
• menyuan basin