山东柴汶河下游古近系朱家沟组含水岩组水文地质特征及地下水富集模式

鲁中南地区古近系朱家沟组是一套具“磨拉石建造”特征的沉积地层,岩性以灰质角砾岩为主,受断裂构造影响,其富水性差异明显。在区域水文地质调查的基础之上,利用柴汶河下游古近系朱家沟组地层调查点与钻孔资料,分析其含水层特征、地下水水化学特征及富水性。结果表明:古近系朱家沟组含水层岩性为钙质胶结灰质砾岩,在90 m以浅裂隙岩溶发育,单井涌水量100~300 m³/d,局部>300 m³/d;裂隙水与汶口盆地南侧岩溶水化学特征相似,表明两者水力联系密切;Gibbs图显示区域地下水呈现岩石风化型,趋向蒸发浓缩型;地下水离子成分主要源于岩盐溶解,并受到人类污染活动影响。依据钻孔资料分析区内地下水富集模式为断裂型灰质砾岩岩溶裂隙蓄水构造模式,认为碎屑岩断裂发育段可作为应急找水靶区。

Hydrogeological Features and Groundwater Enrichment Model of Paleogene Zhujiagou Formation in Lower Chaiwen River Valley,Shandong Province

The Paleogene Zhujiagou Formation in south-central Shandong comprises a molassic sequence dominated by calcareous breccia, and has markedly varying water-yield properties caused by faults. Based on the regional hydrogeological survey in lower Chaiwen River valley, the aquifer characteristics, water-yield properties, and groundwater hydrochemical characteristics are analyzed. The results show that the Zhujiagou Formation comprises calcareous cemented calcirudite, and karst is developed above 90 m depth with single-well yield of 100-300 m³/d, locally reaching >300 m ³/d. Groundwater in the fissured or karst aquifers in the southern Wenkou Basin are similar, indicating close interactions between the two. The Gibbs map demonstrates that the groundwater hydrochemical features are dominated by rock-weathering, and evaporation and concentration. The ions in the groundwater are mainly sourced from rock dissolution and anthropogenic pollution. Based on drill-hole data analysis, the groundwater enrichment model is a fracture-type calcirudite karst-fissure water storage one, and we consider that fractured clastic rocks can be used as an emergency water exploration target.