The relationship between continental chemical weathering trends in the North China Basin and the Late Carboniferous-Early Permian high-latitude glacial cycles

Objective and Methods Late Paleozoic glacial period (LPIA; ca. 360~254 Ma) is the only recorded transition from ice chamber to greenhouse in geological history, which can provide a deep temporal perspective on glacier-environment-climate coevolution and future climate change. In order to deeply understand the potential relationship between the continental chemical weathering trend in the Late Carboniferous-Early Permian low-latitude region and the glacial cycle in the high-latitude Gondwana region, the mudstone of the Benxi-Taiyuan Formation in the Liujiang coalfield of the North China Basin was taken as the research object, and the multiple chemical weathering indicators (CIA, CIW and PIA) calculated from elemental geochemical data of mudstones were used to reconstruct the continental chemical weathering trend and paleoclimatic evolution characteristics of the Liujiang coalfield. Results The results show that the periodic changes of continental chemical weathering in the low-latitude Liujiang coalfield include three weathering weakening stages in the early-middle Bashkir Stage, Moscovites-Kasimov Stage, and early Asshur Stage, and two weathering enhancement stages in the late Bashkir and Geschel stages. This cyclic alternation of weathering trends is closely related to the glacial cycles of the high-latitude Gondwana continent: the downward phase of the weathering trend represents a transition from climatic conditions to relatively cool and dry, which is almost synchronized with the high-latitude glacial period, while the upward phase of the weathering trend represents a change in climatic conditions towards relatively warm and humid, which coincides with the interglacial period at high latitudes. Through comparative analysis, it is found that the frequent volcanic activity, the increase of atmospheric CO₂ concentration, climate warming, the enhancement of the hydrological cycle and the rise of sea level during the interglacial period jointly promote the reduction of tropical rainforest area and the enhancement of continental chemical weathering, which creates favorable conditions for the development of bauxite, while the weakening of volcanic activity, cooling climate, reduction of CO₂ concentration and expansion of rainforest area during the glacial period lead to the weakening of continental weathering, which is conducive to the formation of coal and organicrich mudstone. Conclusions Study results reveals the relationship between the trend of continental chemical weathering in the North China Basin at low latitudes and the distribution of glacial cycles and sedimentary minerals (such as coal and bauxite) in the Gondwana glacier at high latitudes, which provides a new perspective for understanding the complex interaction mechanism of glacier-environment-climate in geological history.