Recharge source, mode and development potential of typical tectonic karst groundwater in the eastern QinghaiXizang Plateau
-
摘要: 【研究目的】青藏高原东部分布多处构造岩溶发育区,岩溶水文地质结构复杂,补给来源多样、水量丰富。开展岩溶水补给源的分析研究,总结高原构造岩溶循环规律,对指导岩溶水资源开发利用、生态保护和防灾减灾具有重要意义。【研究方法】本文在现场调查、流量统测、水化学和稳定同位素分析的基础上,分析了青藏高原东部典型岩溶区地下水补给来源,探讨了补给来源和补给过程的影响因素,构建了构造岩溶地下水补给模式,并提出了开发利用建议。【研究结果】结果表明,青藏高原东部典型岩溶大泉主要补给源是大气降水,通过裂隙溶隙高位直接补给型、高位湖泊持续补给型、汇水洼地持续渗漏补给型、河水渗漏补给型等4种模式得到补给。【结论】存在补给模式差异的原因在于青藏高原东部长期经受内外动力耦合作用,其中内动力控制因素包括岩溶形成演化历史、地质构造和岩性组合;外动力控制因素主要包括气象、地形地貌和冰川运动。根据岩溶大泉水质和水量特征,提出3种开发利用方式:第一种为水质为Ⅰ~Ⅲ类水的岩溶泉,可直接扩大开发利用程度,第二种为微咸水,可与其他水源混合后适当开发利用,第三种为咸水,可适当改造作为旅游开发使用。Abstract: [Objective] There are many tectonic karst areas in the east of Qinghai-Xizang Plateau, with complex karst hydrogeological structure, diverse recharge sources and abundant groundwater. Conducting the analysis and research of recharge sources and summarize the plateau tectonic karst cycle law is of great significance for guiding the development and utilization of karst water resources, ecological protection and disaster prevention and reduction.[Methods] Based on field investigation, flow measurement, hydrochemistry and stable isotope analysis, this paper analyzes the groundwater recharge sources in typical karst areas in the east of Qinghai-Xizang Plateau, the influencing factors of recharge sources and recharge progress were discussed, and suggestions of development and utilization were put forward.[Results] The results show that the main recharge source of the main karst springs in the eastern Qinghai-Xizang Plateau is atmospheric precipitation. Four recharge modes are established, including direct recharge through fissure in high-level, continuous recharge by high-level lake, continuous seepage recharge in catchment depression, river seepage recharge.[Conclusion] The reason for the difference of recharge modes is that the eastern Qinghai Xizang Plateau has experienced internal and external dynamic coupling for a long time, in which the internal dynamic control factors are karst formation and evolution history, geological structure and lithologic combination; The external dynamic control factors mainly include meteorology, landform and glacier movement. According to the characteristics of water quality and quantity of karst spring, three development and utilization modes are put forward:the first is karst spring with water quality of class I~III, which can directly expand the degree of development and utilization, the second is brackish water, which can be properly developed and utilized after mixing with other water, and the third is salt water, which can be properly transformed and used for tourism development.
-
1. 研究目的(Objective)
近年来,新疆阿尔金西段萤石找矿取得的重大突破。萤石矿主要分布于卡尔恰尔—阔什区域性大断裂(阿中断裂)以南的晚奥陶世碱长花岗岩侵入体内及其外接触带附近的富钙质岩系中,圈定了卡尔恰尔—小白河沟、盖吉克—亚干布阳、布拉克北—皮亚孜达坂、托盖里克东南—阿其克南4条沿北东向断裂分布的萤石矿带,整个远景区CaF2资源量已达3500万t以上。中国地质调查局西安矿产资源调查中心于2021—2023年对阿尔金西段小白河沟—克鲁求干道班一带开展了矿产调查评价,在小白河沟地区新发现热液充填型萤石矿产地1处,估算萤石的潜在资源达大型规模,对于拓展阿尔金地区萤石矿床具有借鉴意义。
2. 研究方法(Methods)
在对小白河沟地区以往地物化遥成果资料综合研究基础上,结合本次遥感蚀变异常提取和构造解译圈定了重点工作区,通过开展1∶10000地质草测、1∶10000岩石地球化学剖面测量、1∶500地质剖面测量、槽探及钻探等工作,在小白河沟共圈定萤石矿体21条,实现了找矿突破。通过典型矿床对比,总结了区内萤石矿成矿规律,初步建立了找矿模式,分析了区域萤石成矿潜力及找矿前景。
3. 研究结果(Results)
研究区出露地层基底主要为古元古界阿尔金岩群a岩组和b岩组,二者呈构造面理接触关系。阿尔金岩群a岩组为萤石主要赋矿地层,该岩组出露的岩石类型主要为黑云斜长片麻岩、黑云二长片麻岩、斜长变粒岩、石英岩、大理岩,局部夹有角闪斜长片麻岩(图1b)。区内断裂较为发育,期次较多,主要呈北北东向、北东向、南东东向,南东东向断裂主要与区内的萤石矿化关系密切。地层中岩脉极为发育,在接触带可见岩石具萤石化、钾长石化、碳酸盐化、绿帘石化、硅化等围岩蚀变。
在小白河沟共圈定萤石矿体21条(图1c),长100~1130 m,厚度0.7~4.68 m,矿体沿走向延续性较好,沿倾向呈透镜体状,断续产出,斜切岩体和变质岩,有“膨大缩小”变化,部分呈“透镜体”、“扁豆体”断续分布,主矿体旁侧发育少数分枝。矿体品位23.2%~82.4%,平均品位32.2%,钻孔深部验证效果良好。矿石主要以块状、纹层状为主,主要矿物为萤石,局部发育方解石、带云母和少量石英。萤石以紫色、紫黑色为主,少量呈白色或绿色,具粗晶结构、自形—半自形及他形粒状结构。矿石工业类型主要是CaF2型、CaF2–CaCO3型。围岩蚀变以碳酸盐化、带云母化、钾化、黄铁矿化、绿帘石化、角闪石化等为主。初步估算CaF2资源量117.42万t,具大型萤石矿床远景。
4. 结论(Conclusions)
(1)小白河沟萤石矿是阿尔金西段萤石找矿新发现,这一发现拓展了区内萤石矿向西延伸的空间,同时本次工作区内多数矿体走向和深部延伸均未封边,仍具有较大找矿潜力。
(2)本工作发现了品位较富的大型萤石矿,拓宽了区域找矿思路,具有重要借鉴意义,同时为阿尔金瓦石峡南—卡尔恰尔萤石锂大型资源基地建设提供了有力支撑。
5. 基金项目(Fund support)
本文为中国地质调查局项目(DD20190143、DD20211551、DD20243309)、陕西省自然科学基础研究计划项目(2023−JC−YB−241)、中国地质调查局自然资源综合调查指挥中心科技创新基金项目(KC20230011)联合资助的成果。
计量
- 文章访问数: 8069
- HTML全文浏览量: 82
- PDF下载量: 620