Objective The sand and gravel in the Sanjie area of Juren town， Bin county， Heilongjiang province， was once considered as the lower limit of the Quaternary Luojiawopeng Formation in the Harbin area， but research on its stratigraphic properties and sedimentary environment has been relatively poor to date. This has greatly limited the in-depth understanding of the regional surface processes recorded in this stratum. Methods To discuss and compare the sedimentary environment and stratigraphic division， this study adopted a range of research methods. Sedimentology， mineralogy， elemental geochemistry and detrital zircon U-Pb chronology were used to investigate the chemical weathering characteristics， source rock properties， sedimentary environment and structural background of the source area in this section to determine the effects of chemical weathering， sedimentary cycles and material sources， and to explore the structural background and indicators of stratigraphic delineation and regional magmatic tectonic events. Results It was found that the sediment in the three sections is mainly composed of brownish-yellow sand and gravel mixed with muddy interlayers， with local oblique bedding. The weathering degree of the sand and gravel is low， the sorting is moderate， the roundness is good， and there is no obvious directional arrangement. The gravel rock is mainly granite （46.31%） and quartzite （28.19%）， with some syenite （0.2%）， tuff （0.01%） and schist （0.01%）. The heavy minerals are mainly spinel （65.18%） and epidote （11.87%）， with minor quantities of zircon （2.28%）， apatite （5.60%）， ilmenite （2.77%）， hematite （3.41%） and magnetite （5.15%）； white titanium （0.54%） and pyrrhotite （0.1%） account for less than 1%， and other heavy minerals account for 3.11%. Elemental geochemical analysis revealed that the fine-grained components in the sediments have experienced weak to moderate chemical weathering， and most have undergone initial weathering cycles. Gravel lithology and geochemical composition indicate that the parent rock of the sediments was mainly medium- to acidic magma. The geochemistry of the migration and enrichment of elements in the sediments， paleoclimate discrimination diagrams and sedimentary facies definition indicate that the regional environment of the sediments was a meandering river that transported the sediments over short distances in an arid oxidative environment. The distribution range of detrital zircon U-Pb ages is relatively narrow （134.2-220.3 Ma， peaking at about 168 Ma）. Comparison of the zircon ages of the surrounding potential source areas together with their geomorphological location suggests the detrital contribution of the Zhangguangcai Ridge and indicates the collision and assembly of the Jiamusi and Songnen Blocks， as well as the continuous subduction of the eastern oceanic plate. Significant differences were found between the three sections in terms of their sedimentological characteristics， genetic types and geomorphological features when compared with the standard strata of the Luojiawopeng Formation. It is speculated that formation of the three sections was roughly contemporaneous with the formation time of the Baitushan Formation in western Harbin. Conclusions This study is of great significance for the reconstruction of geological events such as Quaternary stratigraphic divisions and Upper Jurassic tectonic geomorphological-climate-water system evolution in the Harbin area.