Insights into sedimentation information and the environment via soil particle size analysis: A case study of several soil profiles in the Hulunbuir region of Northeast China

The particle size distribution (PSD) and characteristics of soil sediments are important geophysical indicators in sedimentology that can reflect changes in the environment and climate and have become effective factors for tracing the historical evolutionary patterns of sediments. The soil profile, which includes the transported substance source, transportation pattern and sedimentary information, is an important window for obtaining particle size characteristics. To investigate the sedimentary processes in the Hulunbuir Region of the Inner Mongolia Autonomous Region, China, seven representative soil profiles were selected. A comprehensive analysis, integrating both quantitative and qualitative approaches, was conducted on the sedimentary evolution of the study area from multiple perspectives, including PSD curves, fractal characteristics and particle-size parameters. This particle-based analysis aims to reconstruct the sedimentary environments and identify the corresponding sedimentary facies. The results reveal that the ratio of clay to silt in the sediment is less than 0.25. The soil has a high content of coarse particles and a low content of fine particles, which respond to the high energy level of the sedimentary environment, the moderate nature of the conditions and the low plasticity. The soil particle frequency curves reveal mostly bimodal and trimodal patterns, and the M Z of the soil particles are large and poorly sorted, with a mostly positively skewed and very wide peak shape, suggesting that the sediments may have originated from various material sources and that they are characterized as aeolian sediments. The probability accumulation curves show a bipartite pattern (bouncing and suspended fractions), with the jumping fraction having a higher particle content than the suspended fraction and better sorting, reflecting the transportation mode of the riverbed phase at the reaction site. The fractal dimension of sand particles is better than that of silt particles. The high ratio of silt to clay reflects a dry and cold sedimentary environment, whereas the large uniformity value reflects the heterogeneity of the parent material source. All the parameters can be synthesized to reflect that the area has been affected by various sedimentary conditions and that many types of sedimentary facies exist. The sedimentary environment is dominated by fluvial sedimentation. These research results can provide a reference and basis for the study of the sedimentary history and geological evolution of high-latitude cold sediments.