Earth Science Frontiers ›› 2026, Vol. 33 ›› Issue (1): 354-368.DOI: 10.13745/j.esf.sf.2025.10.32

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Development characteristics and formation mechanism of Ordovician paleokarst in the Huainan Coalfield

XU Guangquan1,2(), YANG Tingting1,2,*(), WANG Chuanbing2,3, CHENG Haiyan2,3, ZHU Changhuai2,3, ZHOU Jisheng2,3, HE Shifang2,3   

  1. 1. School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China
    2. State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Huainan 232001, China
    3. Huainan Mining (Group) Co., Ltd, Huainan 232001, China
  • Received:2025-06-20 Revised:2025-09-05 Online:2026-01-25 Published:2025-11-10

Abstract:

The distribution and development of paleokarst systems of the North China Coalfield are the key factors which control deep karst fluid storage and transport. Studying their characteristics, controlling factors, and genesis is essential for assessing karst aquifer water abundance and permeability, and also is of the significance for karst water inrush during mining. Taking the Ordovician paleokarst of the Huainan Coalfield, situated in the southern North China Coalfield as objective, and with such methods as field geological survey, core drilling and microscopic identification, geophysical exploration, and rock geochemistry, the distribution, development characteristics, and controlled factors of Ordovician paleokarst are systematically investigated and studied, combined with regional sedimentary history, structural evolution history, and paleohydrology, the development characteristics and formation process of Ordovician paleokarst are discussed. Results reveal that the Ordovician paleokarst of the Huainan Coalfield is mainly divided into three types: sedimentary karst, epigenetic karst, and tectonic zone karst, which are five forms: breccia, cracks, pores, caves, and karst collapse columns, and which is mostly distributed within 0-50 m of the Ordovician weathering crust, and which internal fillings can be divided into three types: rock debris, chemical bonding materials, and mixed materials. The degree of ancient karst development is controlled by factors including carbonate rock lithology and structure, diagenetic geological processes, geological structural evolution, and paleohydrology. The formation of Ordovician paleokarst has evolved from the consolidated stage during carbonate deposition, to the stage of weathering and erosion owing to plate uplift, and to the stage of tectonic activity during the Late Yanshanian Movement. Besides, the formation process of paleokarst also is related to the leaching and dissolved effects, paleo-atmospheric freshwater, and deep hydrothermal activity. Therefore, different types of paleokarst are the results of multi-stage karst reconstruct.

Key words: Ordovician paleokarst, karst breccia, karst collapse column, Huainan Coalfield

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