New Model for Orbital Forcing Salt Formation in the Qaidam Basin

The formation of salt resources is controlled by three key factors: sedimentary basins, arid climates, and source material replenishment.Previous studies have mainly focused on the notable roles of tectonic activity and the sedimentary environment in the salt-forming process while neglecting the key factors of arid and extremely arid climate events and their coupling mechanisms in the formation of salt layers in basins.This study reconstructed the hydroclimatic evolutionary history of the Qaidam Basin based on a multidisciplinary analysis, including rock magnetism, environmental magnetism, elemental and isotopic geochemistry, and palynological studies on a deep drilling core in the Chahanslta Depression of the western Qaidam Basin.The salt formation process and related mechanisms were further investigated based on a comprehensive analysis of published and newly obtained data from the SG-1 core by tracing the temporal and frequency domain evolution patterns and the system dynamics evolution characteristics of these data.The results reveal four key periods of salt layer development in the western Qaidam Basin since 2.7 Ma, specifically during 2.2–1.95 Ma, 1.3–1.1 Ma, 0.85–0.65 Ma, and 0.5–0.3 Ma.We suggest that reduced seasonality and increased meridional moisture transport, promoted by the co-occurrence of low obliquity amplitudes and low eccentricity, would have facilitated the ice sheet expansion in the Northern Hemisphere.This would have subsequently affected the climate and hydrological cycle of Qaidam Basin by regulating the position and intensity of the Northern Hemisphere westerlies, controlling the occurrence of arid events and the development of salt layers within the basin.Further comparative analysis confirmed that on orbital-suborbital-millennial scales, global ice volume and climate change in the high latitudes of the Northern Hemisphere notably control the arid climate and salt layer development in the Qaidam Basin.This orbital parameter controlling the arid climate evolution and the salt-forming process has been shown to be applicable throughout the entire basin.This leads to the development of salt layers in different depressions of the Qaidam Basin, despite bearing some differences, the development of their major salt layer predominantly concentrated in the aforementioned four key periods.These research findings offer novel theoretical insights and methodological approaches for understanding the processes and mechanisms underlying salt formation in the Qaidam Basin and other arid areas.Furthermore, these findings provide a remarkable foundation for future studies that will explore the interplay between tectonic, climatic, and source material variations to delineate the diverse types and patterns of salt resource development across various regions as well as unravel the deep-time evolution of these salt resources.