Objective The upper and middle reaches of the Yellow River basin represent significant coal bases of China, while burnt rocks formed by the high temperature of coal fires greatly affect the safe and green coal mining in this region. Therefore, investigating the distribution patterns and geological genetic mechanisms of burnt rocks in this region is of great scientific significance and practical value.
Methods This study systematically investigated the distribution range and patterns of burnt rocks in the upper and middle reaches of the Yellow River basin. Using analysis of geological processes, this study explored the geological genetic mechanisms and primary controlling factors of burnt rocks in different areas across the upper and middle reaches.
Results and Conclusion The burnt rocks in the upper and middle reaches of the Yellow River basin are predominantly exposed in the Hancheng section in Shaanxi Province, the Shaanxi-Shanxi-Inner Mongolia (SSIM) section, the Helanshan section, and the Yaojie section in Gansu Province, exhibiting a zonal distribution pattern along basin margins, as well as the Yellow River and its tributaries. The formation and development of the burnt rocks were governed by geological-tectonic processes. Specifically, the burnt rocks in the Hancheng section were subjected to the compressional uplift of large-scale Yumenkou majior fault (i.e., the Hancheng fault) during the Yanshanian, while those in the SSIM section were influenced by multi-stage regional uplift and denudation. In the Helan Mountain section, burnt rocks were formed primarily due to intense compressional tectonic activities, especially the Yanshanian movement since the Late Jurassic and the Himalayan movement since the Eocene. In contrast, the burnt rocks in the Yaojie section were significantly influenced by the east compressive shear fault, which was formed by the compressional movements during the Yanshanian and Himalayan. The distribution of burnt rocks in the upper and middle reaches of the Yellow River basin is closely associated with the intense Yanshanian tectonic activities in the Ordos and Minhe basins. During the Cenozoic, faults were formed at the periphery of the Ordos Basin, and basin-mountain coupling intensified. Concurrently, the modern Yellow River was formed, inducing intense denudation and downward erosion. These activities represent the key reasons for the zonal distribution of burnt rocks formed by the high temperature attributed to the spontaneous combustion of coal seams. The results of this study can provide a theoretical guide for the prevention and control of water hazards, as well as ecological protection, for regional coal mining in the upper and middle reaches of the Yellow River basin.
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