柳江盆地岩浆活动对主力煤田水文地质特征的影响

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

  • 摘要: 柳江盆地内及其周缘经历了多期次的岩浆活动,在盆地内及其周缘形成了大面积的岩浆岩体,为探究岩浆对盆地石炭二叠系主力煤田水文地质特征的影响。首先,采用地面水文地质调查结合9个水文动态观测站1个水文年的观测与统计,分析地表水、地下水的补给、径流、排泄关系;其次,采用1∶10 000水文地质填图结合生产矿井水文地质调查、机、民井抽水试验,水地球化学采样测试,分析盆地构造形态和含隔水层水文地质特征、划分盆地水文地质单元;然后,在不同构造位置和水文地质单元内部署了6个水文地质勘查钻孔,完成了13层次抽水试验,结合62个地质勘查孔的岩芯精细描述、水地球化学测试、含水层的孔隙度、渗透率、含水率等物性特征和煤层顶底板岩石力学样品采集与测试,分析岩浆岩对主力煤田含隔水层物性特征的影响;之后,通过奥陶系地下水连通试验和矿井与钻孔的联合抽水试验,分析地下水的径流及其岩浆岩对地下水流场的影响;最后,综合分析盆地内矿井的充水因素、涌水量特征及其矿井水害特征,提出矿井防治措施,指明供水水源勘查方向。研究表明地下水补给来源主要为盆地四周露头区的大气降水、其次为大石河等地表水;径流方向为自北向南,自东、西向中部径流;主要以泉眼、矿井和水源井抽水的形式排泄,不同的季节和流域内河流水与地下水补给相互转换;盆地四周的岩浆岩体是良好的隔水边界和水文地质单元划分边界,盆地内岩浆岩的侵入、喷发改变了煤层及其顶底板含、隔水层的水文地质特征,阻挡了底部奥陶系灰岩岩溶高承压含水层对矿井的威胁;东、西两翼燕山期岩浆的喷发改变了盆地的构造格局,形成了目前断陷盆地的基底构造形态;西翼的断裂构造和中部裂隙状火山通道改变了盆地地下水流场及其含水层的富水性分布特征,表现为西翼富水、东翼缺水的分布格局;西翼的推覆构造体上盘的灰岩含水层分布区和东翼深部的隐伏灰岩含水层是找水的目的层位;西翼断裂构造带、东翼岩浆未侵入区的奥陶系灰岩岩溶水和大石河地表水以及浅部大量分布的小窑积水采空区是矿井水害防治的关键。

     

    Abstract: 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.

     

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