Tectonic control law and zoning division of coalmine gas occurrence in Shanxi Province

The frequent occurrence of gas disasters in coal mines is primarily attributed to an unclear understanding of gas occurrence laws. Tectonic control law of coalmine gas occurrence in Shanxi Province was analyzed by utilizing massive gas-geology data of Shanxi Province coal mine, as well as insights from studies on gas occurrence patterns and their impact on coal mine safety. Furthermore, gas zoning division and its characteristics has been discussed. Shanxi Province is located in the middle of the North China block, between two East-West trending giant tectonic belts (Qinling tectonic belts and Inner Mongolia tectonic belts) in the north and south, and also in the North-Northeast trending Daxinganling-Taihang Mountain tectonic belt, and its coal forming environment and gas occurrence are controlled by its tectonic evolution. During the Indosinian period, in most parts of Shanxi Province, continuous deposition of Triassic and Permian sediments facilitated coal metamorphism and hydrocarbon generation. Yanshan movement resulted in fold and thrust nappe zones, with coal bodies compressed into tectonic coal, favoring gas outbursts. At the same time, following a series of magmatic activities during the Yanshanian period, the degree of coal metamorphism increased and secondary hydrocarbon generation occurred. During the Himalayan period, compression was gradually replaced by tension. After a series of tension rifting, the mountains of the Loess Plateau experienced denudation, facilitating the escape of gas. Gas occurrence zoning in Shanxi Province was categorized into three high gas outburst belts and two low gas belts, namely, the Qinshui Basin, Hedong coalfield, and Xuangang Xishan’s three high gas outburst belts, North Shanxi uplift and Fenwei rift two low gas belts.