黄山北麓岩浆岩区断裂构造富水性及蓄水构造

    Water yield property and water storage structure of magmatic fracture structure in the northern Huangshan area

    • 摘要: 黄山北麓地区位于江南造山带与皖南褶断带交接处,出露晚侏罗世太平花岗闪长岩和早白垩世黄山花岗岩,同岩浆期或期后构造运动强烈,近SN向断裂和NE向断裂发育,控制了研究区的水系分布。块状均一的侵入岩富水性差,为寻找单井地下水出水量大于240 m3/d的孔位,实施了遥感水文地质解译、地质测量、电法剖面测量及水文试验孔验证,基本查明研究区断裂构造的富水性、地下水蓄水构造等水文地质特征。研究发现: 研究区风化网状节理、顺坡向卸荷节理、成岩节理及构造节理发育,为地下水接受地表水和降水入渗补给的主要通道。通过电法剖面测量,对圈定的低阻异常实施水文试验孔钻探。钻孔验证显示黄山北麓张性断裂、正平移断裂具有中等渗透性,为地下水导水构造,在两组以上方向断裂或断裂与岩脉交汇处可布置水文试验孔。多组方向断裂交汇处、地形低洼处断裂与岩脉阻水构造交切部位是有利找水点位,研究区不同岩性接触带富水性弱,洼地风化带型、断裂型及岩脉型蓄水构造富水性中等,3种类型叠加的蓄水构造处富水性好。研究成果可为黄山地区后续开展地下水水源地评价与合理开发利用提供技术参考。

       

      Abstract: The Northern Huangshan area is located at the junction between Jiangnan orogenic and fault-fold structural belt of the southern Anhui Province, and its outcrop is Taiping granodiorite of Late Jurassic and Huangshan granite of Early Cretaceous. The structure activity of comagmatic or post-magmatic was intensive, and the nearly north-south fracture and north-west fracture was well-developed, which controlled the drainage system distribution. Massive intrusive rock was in poor water yield property in the study area, so the remote sensing hydrogeological interpretation, geological surveying, electrical profiling measurement, and hydrological test borehole for verification were conducted to find the location of single well with water inflow of more than 240 m3/d. The water-bearing characteristics and groundwater storage structures of the faulted structures in the study area were basically clarified. Through surface investigation, the authors found that the study area has developed weathering reticulate jointing, dip-slope unloading jointing, diagenetic jointing, and structure jointing, which were the main channels for groundwater to receive recharge from surface water and precipitation. Besides, the low resistance anomalies were identified through electrical profiling measurement, and the hydrological test holes were implemented. It is recognized that the tensile fractures and normal transecting fractures in the northern Huangshan area had medium permeability through borehole verification, and those fractures were water-conducting structures. Hydrological test holes could be placed at the intersection of more than two sets of directional fractures or at the intersection of fractures and rock veins. The authors in this research recognized that the intersection of multiple sets of directional fractures, low-lying terrain fracture intersections with dike rock, and water-blocking structures were favorable locations for water exploration. The water yield property of the contact zone between different lithology types in the study area was weak, and water yield property was middle for depression weathered belt type, fracture structure models type and dike type. And the water-bearing structure with the superposition of the three types had good water yield property. These research results could provide technical references for further exploration of groundwater resource and its rational utilization in Huangshan area.

       

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