Influence of magmatic activities in Liujiang Basin on hydrogeological charac teristics of main coalfields

Liujiang Basin had experienced many periods of magmatic activities,a large area of magmatic rock mass was formed in and around the basin after several periods of magmatic activities.In order to explore the influence of magma on the hydrogeological characteristics of the main coalfield of the carboniferous Permian in the Liujiang Basin,firstly,the recharge,runoff and discharge relationships of surface water and groundwater were analyzed by using surface hydrogeological survey combined with the observation and statistics of nine hydrological dynamic stations for one hydrological year.Secondly,the 1∶10 000 hydrogeological mapping was combined with the hydrogeological survey of the mine,the pumping test of machine and people’s well,and the water sampling test of the geochemistry to analyze the structural configuration of the basin and the hydrogeological characteristics of the Aquifer,and divide the hydrogeological units of the basin.Thirdly,deploying six hydrogeological exploration boreholes and 13-level pumping tests in different structural positions and hydrogeological units,based on the detailed core description of 62 geological exploration holes,water geochemistry test,porosity,permeability and water cut of the Aquifer,and the collection and testing of mechanical samples from the roof and floor of the coal seam,the influence of igneous rock on the physical properties of the Aquifer in the main coalfield was analyzed.Fourthly,the influence of groundwater runoff and magmatic rock on the groundwater flow field was analyzed through the Ordovician groundwater connection test and the combined pumping test of mine and borehole.Finally,the paper analyzed the factors of mine water-filling,the characteristics of water inflow and mine water disaster in the basin,put forward the measures of mine water prevention and control,and pointed out the direction of water supply source exploration.The study shows that the main source of groundwater recharge is precipitation in outcrop area around the basin,then surface water such as Dashihe,and the direction of runoff is from north to south,from east and west to middle.The drainage is mainly in the form of pumping water from springs,mines and water source wells.The recharge of river water and groundwater in different seasons and river basins is mutually transformed.The intrusion and eruption of the magmatic rock in the basin change the hydrogeological characteristics of the coal seam and its top and bottom water-bearing and water-resisting layers,and block the threat of the Ordovician limestone karst high confined aquifer to the mine.The eruptions of Yan Mountains period magma in the East and West Wings change the structural pattern of the basin and form the basement structure of the present rift basin.The fault structure in the West Wing and the fissure-like volcanic passage in the middle of the basin change the groundwater flow field and the water-rich distribution characteristics of the aquifer in the basin,showing the distribution pattern of water-rich in the West Wing and water-deficient in the East Wing.The distribution area of limestone aquifer in the hanging wall of the NAPPE structure in the West Wing and the buried limestone aquifer in the deep part of the east wing are the target horizons for water prospecting The key points of mine water control are the West Wing fault zone,the Ordovician limestone karst water in the East Wing non-intrusive Magma area,the surface water of Dashihe and the large amount of shallow small kiln water-accumulated goaf.