Paleopedological record of Mid-Pleistocene transition of west Transbaikalia, Russia, Tarbagatay key sequence

• Sandy-textured soils in Transbaikalia preserve long-term soil memory, enabling paleoenvironmental reconstructions. • The soil developed during the Mid-Pleistocene Transition reflects deeper pedogenic weathering intensity. • Soils formed after the Mid-Pleistocene Transition are less developed and represent colder paleoenvironmental conditions. The Mid-Pleistocene Transition (MPT), occurring between 1.2 million and 750 thousand years ago, marked a fundamental shift in Earth’s climate system. While well-documented in marine and terrestrial archives, its impact on soil formation remains poorly understood due to the scarcity of terrestrial records from this period. This study examines the Tarbagatay key section in West Transbaikalia, which preserves approximately one million years of paleoenvironmental history. Using mineralogical, micromorphological, and geochemical analyses—including CaCO 3 content, total organic carbon, and texture— distinct pedogenic patterns across two sedimentary Units were identified. The Lower Unit (13.6–23 m), which correlates to the period of MPT, displays clay-loamy texture and more intensive weathering, marked by pronounced secondary carbonate accumulation and cambic properties. In contrast, the Upper Unit (0–13.6 m), formed after the MPT, is dominated by sandy sediments, reflecting a transition to more frequent landscape reworking and colder conditions following the MPT. These findings support broader Northern Hemisphere trends, where the MPT facilitated deeper pedogenesis, while post-transition soils exhibit stronger landscape dynamics and increased cryoturbation. Our results highlight the significance of paleosols as archives of environmental change and contribute to a more comprehensive understanding of Mid-to-Late Pleistocene impact on pedogenic processes.