The Longtan River Hot Springs Formation Mechanism And Water Resources Situation

Spring is a valuable geothermal resources, has its special economic and environmental benefits. Located in the of Wanyuan old hospital of the town of Red Rock Village near the Longtan River Hot Springs in March2012by artificial successfully drill. Its depth of1700m, the water volume of2160m3/d, well head temperature of40℃, pressure0.75MPa. In order to have a complete understanding for the mechanism and water resources situation of hot springs to Longtan River and provide a basis for local geothermal water resource utilization and protection, the geological structure, water geochemical and Water issues are selected on the basis of the predecessor’s exploration and research which related to the Longtan River Hot Springs to analysis and research in-deathly.Firstly, through remote sensing geological interpretation of the middle of South Dab Mountain and Wan Yuan areas, combined with the field investigation and previous research to verify the buried geological structure of the remote sensing geological interpretation and found some latest concealed fault and fold, such as north-south of the big cave fault fold belt, phoenix mouth synclinorium which is comprised of Xiaozhanxi anticline in the fault fold belt which in the middle of north west-south east to the Hongyan syncline and Dazhanxi syncline. Discussed the regularity of groundwater enrichment and considered phoenix mouth synclinorium is the main water-bearing structure in the research area.Using geophysical exploration and combined with the regional strata and hydrological geology data in the study area to determine the groundwater in study area is karts water which strongly developed in underground rivers of the cave; it belongs to carbonate fissure cave water. And divided the Longtan river area to three types of rock strata combination of groundwater, respectively is the combination of the Lower Triassic-upper Permian strata combination, lower Permian-Silurian strata combination, and the Silurian-Cambrian strata combination, so favorable water-bearing structure and rock strata combination is the guarantee to groundwater accumulation in reservoir.After testing the water quality of the study area well (spring) and analysis chemical characteristics about ions and chemical element indexes in groundwater concluded that the groundwater chemical types are mainly HCO3-Ca、HCO3-Ca-Mg in the study area belong to Bicarbonate type. Groundwater is weakly alkaline, soft-micro hardness of fresh water. The Longtan River groundwater recharge mainly comes from atmospheric precipitation which depends on the major anions and cations analysis. And the source of the LongTan river hot spring water also is not high temperature hot water in deep underground, the main source of atmospheric precipitation, followed by a part of the ancient sedimentary water.At the same time, choosing appropriate geochemical thermometric scale to estimate heat reservoir temperature, its show as the Medium-low temperature characteristics. Through the K-Mg geochemical thermometric scale estimates the thermal reservoir temperature. The LongTan river hot spring forming mechanism was analyzed based on the above information, this area without young magma activity and LongTan river hot spring water supply mainly from atmospheric precipitation, when good aquifer or bedrock fissure which exposed surface is developed can directly accept the infiltration of precipitation and surface water supplies. In addition, part of the ancient sedimentary water is also involved in the Longtan River hot spring water supply.In the study area strong tectonic activities and developed lots of multiple syncline Anticline and multiple faults, resulting in surface and underground fracture development. The rock lithology is carbonate and easy to produce the runoff channels such as whole, fractures. Phoenix mouths multiple synclines and the lower Permian-Silurian water-bearing rock stratum combination is the effective space for hot spring gathered into a reservoir. Therefore, the LongTan river hot spring should appear in the "Under the condition of regional heat flow is normal or high background and young magmatic activity in the depths of the earth as an additional heat source, underground hot water circulation system will appear in fractured medium or fractured zones, that is low-medium temperature geothermal system of convective type.According to the relevant national water quality evaluation standard, we evaluate the water quality of the Longtan River Hot Spring. The Longtan River hot spring’s two indicators have reached the national physiotherapy hot mineral water standard which is fluorine, strontium and mineralization degree respectively. Silicate content has reached of the medical value of mineral water limits and has high medical value. But it is not suitable for direct use as drinking water. In addition, according to preliminary calculations of groundwater resources of the Longtan River area, the amount of resources is considerable and has excellent development and utilization prospect.