Research On The Formation Conditions And Causes Of Denggeng Hot Springs In Nujiang Prefecture, Yunnan Province

Denggeng geothermal area of Lushui City belongs to the Nujiang Dong Autonomous Prefecture of Yunnan Province;it is located in the western part of Yunnan Province and is located in the anticline ridge.The geothermal heat in the survey area shows that there are many hot springs,and the temperature of the hot spring is about 49?-73?.However,due to the lack of geothermal research in this area and the poor understanding of the geothermal structure and migration model,the development and utilization of geothermal resources are still not comprehensive and efficient.In this paper,we take the Denggeng geothermal area as the main research object,collect geothermal water samples from the study area,and analyze the hydrogeochemical characteristics.At the same time,we combine the local geothermal geological background and the collected geological and hydrological data.The four major elements of the geothermal system:caprock,thermal reservoir,hot aisle,and heat source are studied,and the conceptual model of the Dengfeng geothermal system is obtained through analysis.And based on this research,the geothermal water storage and thermal storage water resources in the study area were calculated and evaluated using the geothermal water storage method and volume method,which provided a very useful basis for the future development and utilization of geothermal resources in the Denggeng geothermal area.The basis of meaning.By analyzing the characteristics of water chemistry,it is concluded that geothermal water in the study area is weakly alkaline water,the type of water chemistry is relatively simple,mainly HC0₃^-—Ca²⁺type,and the degree of mineralization is relatively low.The temperature of the thermal reservoir of the geothermal system was calculated by the cation temperature scale method and the silica geothermal algorithm.The temperature of the geothermal system was approximately 82?.The Na-K-Mg triangle diagram method was used to analyze the geothermal water as immature water.,Which was mixed with cold water.According to the collected data,the characteristics analysis of the hydrogen and oxygen isotopes and tritium isotopes show that the source of hot water recharge in the Denggeng geothermal area is atmospheric precipitation.The recharge analysis analyzes the elevation effect of?¹⁸O,and obtains the hot water recharge height of1445m.The characteristics of the trace elements further explained that the source of the hot spring water came from the carbonate rock layer.According to the ¹⁴C radioactive element analysis,the geological age of the Denggeng hot spring water was approximately 19500±320 years.The thermal reservoirs of the geothermal system in the Denggeng geothermal area are the Carboniferous Lower Datang Formation Pumenqian Formation(C₁p)and the Carboniferous Lower Yanguan Formation Xiangshan Formation(C₁x).Its heat source comes from the heat flow of the upper mantle and the decay of radioactive elements,and conducts heat and water flow through the fissure zone of the core of the regional anticline structure.The geothermal resources of Dengfeng geothermal area calculated by relevant methods are 2.18×l0¹⁴KJ,and the heat release amount is 7.3×10¹⁰KJ per year.This result indicates that the geothermal resources of Denggeng geothermal area are very rich and the exploitation potential is very large.At the same time,the hot spring water quality was analyzed,and the results met the national drinking mineral water standards.